The neural basis of phonological working memory was investigated through an examination of the effects of irrelevant speech distractors and disruptive neural stimulation from transcranial magnetic stimulation. Embedded processes models argue that the same regions involved in speech perception are used to support phonological WM whereas buffer models assume that a region separate from speech perception regions is used to support WM. Thus, according to the embedded processes approach but not the buffer approach, irrelevant speech and TMS to (...) the speech perception region should disrupt the decoding of phonological WM representations. According to the buffer account, decoding of WM items should be possible in the buffer region despite distraction and should be disrupted with TMS to this region. Experiment 1 used fMRI and representational similarity analyses with a delayed recognition memory paradigm using nonword stimuli. Results showed that decoding of memory items in the speech perception regions was possible in the absence of distractors. However, the decoding evidence in the left STG was susceptible to interference from distractors presented during the delay period whereas decoding in the proposed buffer region persisted. Experiment 2 examined the causal roles of the speech processing region and the buffer region in phonological WM performance using TMS. TMS to the SMG during the early delay period caused a disruption in recognition performance for the memory nonwords, whereas stimulations at the STG and an occipital control region did not affect WM performance. Taken together, results from the two experiments are consistent with predictions of a buffer model of phonological WM, pointing to a critical role of the left SMG in maintaining phonological representations. (shrink)

Researchers are enthusiastically concerned about neural stem cell (NSC) therapy in a wide array of diseases, including stroke, neurodegenerative disease, spinal cord injury (SCI) and depression. Although enormous evidences have demonstrated that neurobehavioral improvement may benefit from NSC-supporting regeneration in animal models, approaches to endogenous and transplanted NSCs are blocked by hurdles of migration, proliferation, maturation and integration of NSCs. Electrical stimulation (ES) may be a selective nondrug approach for mobilizing NSCs in the central nervous system (CNS). This technique (...) is suitable for clinic application, because it is well established and its potential complications are manageable. Here, we provide a comprehensive review of the emerging positive role of different electrical cues in regulating NSC biology in vitro and in vivo, as well as biomaterial-based and chemical stimulation of NSCs. In the future, ES combined with stem cell therapy or other cues probably becomes an approach for promoting brain repair. (shrink)

Research into the neural correlates of consciousness (NCCs) has blossomed, due to the advent of new and increasingly sophisticated brain research tools. Neuroimaging has uncovered a variety of brain processes that relate to conscious perception, obtained in a range of experimental paradigms. But methods such as functional magnetic resonance imaging or electroencephalography do not always afford inference on the functional role these brain processes play in conscious vision. Such empirical NCCs could reflect neural prerequisites, neural consequences, or (...) neural substrates of a conscious experience. Here, we take a closer look at the use of non-invasive brain stimulation (NIBS) techniques in this context. We discuss and review how NIBS methodology can enlighten our understanding of brain mechanisms underlying conscious vision by disentangling the empirical NCCs. (shrink)

Background: In prior reports, we described the design and initial performance of a fully implantable, bi-directional neural interface system for use in deep brain and other neurostimulation applications. Here we provide an update on the chronic, long-term neural sensing performance of the system using traditional 4-contact leads and extend those results to include directional 8-contact leads.Methods: Seven ovine subjects were implanted with deep brain stimulation leads at different nodes within the Circuit of Papez: four with unilateral leads in (...) the anterior nucleus of the thalamus and hippocampus; two with bilateral fornix leads, and one with bilateral hippocampal leads. The leads were connected to either an Activa PC+S® or Percept PC°ledR deep brain stimulation and recording device. Spontaneous local field potentials, evoked potentials, LFP response to stimulation, and electrode impedances were monitored chronically for periods of up to five years in these subjects.Results: The morphology, amplitude, and latencies of chronic hippocampal EPs evoked by thalamic stimulation remained stable over the duration of the study. Similarly, LFPs showed consistent spectral peaks with expected variation in absolute magnitude dependent upon behavioral state and other factors, but no systematic degradation of signal quality over time. Electrode impedances remained within expected ranges with little variation following an initial stabilization period. Coupled neural activity between the two nodes within the Papez circuit could be observed in synchronized recordings up to 5 years post-implant. The magnitude of passive LFP power recorded from directional electrode segments was indicative of the contacts that produced the greatest stimulation-induced changes in LFP power within the Papez network.Conclusion: The implanted device performed as designed, providing the ability to chronically stimulate and record neural activity within this network for up to 5 years of follow-up. (shrink)

Sustained peripheral somatosensory stimulations, such as high-frequency repetitive somatosensory stimulation (HF-RSS) and vibrated stimulation, are effective in altering the balance between excitation and inhibition in the somatosensory cortex (S1) and motor cortex (M1). A recent study reported that whole-hand water flow (WF) stimulation induced neural disinhibition in the M1. Based on previous results, we hypothesized that whole-hand WF stimulation would lead to neural disinhibition in the S1 because there is a strong neural connection between M1 and S1 (...) and aimed to examine whether whole-hand WF stimulation would change the neural balance between excitation and inhibition in the S1. Nineteen healthy volunteers were studied by measuring excitation and inhibition in the S1 before and after each of the four 15-min interventions. The excitation and inhibition in the S1 were assessed using somatosensory evoked potentials (SEPs) and paired-pulse inhibition (PPI) induced by single- and paired-pulse stimulations, respectively. The four interventions were as follows: control, whole-hand water immersion, whole-hand WF, and HF-RSS. The results showed no significant changes in SEPs and PPI following any intervention. However, changes in PPI with an interstimulus interval (ISI) of 30 ms were significantly correlated with the baseline value before whole-hand WF. Thus, the present findings indicated that the whole-hand WF stimulation had a greater decreased neural inhibition in participants with higher neural inhibition in the S1 at baseline. Considering previous results on M1, the present results possibly show that S1 has lower plasticity than M1 and that the duration (15 min) of each intervention may not have been enough to alter the balance of excitation and inhibition in the S1. (shrink)

ObjectiveThe effects and possible mechanisms of cerebellar high-frequency repetitive transcranial magnetic stimulation on swallowing-related neural networks were studied using resting-state functional magnetic resonance imaging.MethodA total of 23 healthy volunteers were recruited, and 19 healthy volunteers were finally included for the statistical analysis. Before stimulation, the cerebellar hemisphere dominant for swallowing was determined by the single-pulse TMS. The cerebellar representation of the suprahyoid muscles of this hemisphere was selected as the target for stimulation with 10 Hz rTMS, 100% resting motor (...) threshold, and 250 pulses, with every 1 s of stimulation followed by an interval of 9 s. The motor evoked potential amplitude of the suprahyoid muscles in the bilateral cerebral cortex was measured before and after stimulation to evaluate the cortical excitability. Forty-eight hours after elution, rTMS was reapplied on the dominant cerebellar representation of the suprahyoid muscles with the same stimulation parameters. Rs-fMRI was performed before and after stimulation to observe the changes in amplitude of low-frequency fluctuation and regional homology at 0.01–0.08 Hz, 0.01–0.027 Hz, and 0.027–0.073 Hz.ResultsAfter cerebellar high-frequency rTMS, MEP recorded from swallowing-related bilateral cerebral cortex was increased. The results of rs-fMRI showed that at 0.01–0.08 Hz, ALFF was increased at the pons, right cerebellum, and medulla and decreased at the left temporal lobe, and ReHo was decreased at the left insular lobe, right temporal lobe, and corpus callosum. At 0.01–0.027 Hz, ALFF was decreased at the left temporal lobe, and ReHo was decreased at the right temporal lobe, left putamen, and left supplementary motor area.ConclusionRepetitive transcranial magnetic stimulation of the swallowing cortex in the dominant cerebellar hemisphere increased the bilateral cerebral swallowing cortex excitability and enhanced pontine, bulbar, and cerebellar spontaneous neural activity, suggesting that unilateral high-frequency stimulation of the cerebellum can excite both brainstem and cortical swallowing centers. These findings all provide favorable support for the application of cerebellar rTMS in the clinical practice. (shrink)

Libet discovered that a substantial duration (> 0.5-1.0 s) of direct electrical stimulation of the surface of the somatosensory cortex at threshold currents is required before human subjects can report that a conscious somatosensory experience had occurred. Using a reaction time method we confirm that a similarly long stimulation duration at threshold currents is required for activation of elementary visual experiences (phosphenes) in human subjects following stimulation of the surface of the striate cortex. However, the reaction times for the subject (...) to respond to the cessation of the visual experience after the end of electrical stimulation could be as brief as 225-242 ms. We also carried out extensive studies in cats under a variety of anesthetic conditions using the same electrodes and parameters of stimulation employed in the human studies to study the patterns of neuronal activity beneath the stimulating surface electrode. Whereas sufficiently strong currents can activate neurons within milliseconds, stimulating currents close to threshold activate sustained neural activity only after at least 350-500 ms. When currents are close to threshold, some neurons are inhibited for several hundreds of millisecond before the balance between inhibition and excitation shifts towards excitation. These results suggest that the prolonged latencies, i.e., latencies beyond 200-250 ms, for the emergence of conscious experience following direct cortical stimulation result from a delay in the sustained activation of underlying cortical neurons at threshold currents rather than being due to any unusually long duration in central processing time. Intracellular records from cortical neurological cells during repetitive electrical stimulation of the surface of the feline striate cortex demonstrate that such stimulation induces a profound depolarizing shift in membrane potential that may persist after each stimulus train. Such a depolarization is evidence that extracellular K+ concentrations have increased during electrical stimulation. Such an increase in extracellular K+ progressively increases cortical excitability until the threshold for sustained activation of cortical neurons is reached and then exceeded. Consequently, the long latency for threshold activation of cortical neurons depends upon a dynamically increasing cortical facilatory process that begins hundreds of milliseconds before there is sustained activation of such neurons. In some cases, this facilatory process must overcome an initial stimulus-induced inhibition before neuronal firing commences. (shrink)

Although complex hallucinations are extremely vivid, painful symptoms in schizophrenia, little is known about the underlying mechanisms of multisensory integration in such a phenomenon. We investigated the neural basis of these altered states of consciousness in a patient with schizophrenia, by combining state of the art neuroscientific exploratory methods like functional MRI, diffusion tensor imaging, cortical thickness analysis, electrical source reconstruction and trans-cranial magnetic stimulation. The results shed light on the functional architecture of the hallucinatory processes, in which unimodal (...) information from different modalities is strongly functionally connected to higher-order integrative areas. (shrink)

It has been well documented that the auditory system in the superior temporal cortex is responsible for processing basic auditory sound features, such as sound frequency and intensity, while the prefrontal cortex is involved in higher-order auditory functions, such as language processing and auditory episodic memory. The temporal auditory cortex has vast forward anatomical projections to the prefrontal auditory cortex, connecting with the lateral, medial, and orbital parts of the prefrontal cortex. The connections between the auditory cortex and the prefrontal (...) cortex thus help in localizing, recognizing, and comprehending external auditory inputs. In addition, the medial prefrontal cortex is believed to be a core region of episodic memory retrieval and is one of the most important regions in the default mode network. However, previous neural evidence with regard to the comparison between basic auditory processing and auditory episodic memory retrieval mainly comes from fMRI studies. The specific neural networks and the corresponding critical frequency bands of neuronal oscillations underlying the two auditory functions remain unclear. In the present study, we reported results of direct cortical stimulations during stereo-electro-encephalography recording in a patient with drug-resistant epilepsy. Electrodes covered the superior temporal gyrus, the operculum and the insula cortex of bilateral hemispheres, the prefrontal cortex, the parietal lobe, the anterior and middle cingulate cortex, and the amygdala of the left hemisphere. Two types of auditory hallucinations were evoked with direct cortical stimulations, which were consistent with the habitual seizures. The noise hallucinations, i.e., “I could hear buzzing noises in my head,” were evoked with the stimulation of the superior temporal gyrus. The episodic memory hallucinations “I could hear a young woman who was dressed in a red skirt saying: What is the matter with you?,” were evoked with the stimulation of MPFC. The patient described how she had met this young woman when she was young and that the woman said the same sentence to her. Furthermore, by analyzing the high gamma power induced by direct electrical stimulation, two dissociable neural networks underlying the two types of auditory hallucinations were localized. Taken together, the present results confirm the hierarchical processing of auditory information by showing the different involvements of the primary auditory cortex vs. the prefrontal cortex in the two types of auditory hallucinations. (shrink)

This article describes key paradigms employed to assess deception and reviews the main neuroscience-based technologies that have been employed to investigate the neural correlates of deception: electroencephalography, functional magnetic resonance imaging, and transcranial direct current stimulation. Any potential use of neuroscience-based methods to detect deception in real-life situations requires successful classification in single subjects. It describes findings on the single subject performance of these methods and addresses the effects of two factors that are problematic for all deception detection methods, (...) the potential use of countermeasures, strategies used by subjects to defeat the deception detection tests, and the potential role of false memories and of incidental encoding. It briefly outlines some of the ethical issues associated with these technologies to detect deceptive behavior. (shrink)

There is evidence of reciprocal connectivity, similarity of oscillatory responses to stimulation of multiple motor and somatosensory cortices, whole system oscillation, and short- latency responses to behavioral perturbation. These suggest that frame/content may be instantiated by overlapping neural populations, and that the genesis of frame oscillations may be profitably thought of as an emergent property of a distributed neural system.

Face perception plays a central role in social communication and is, arguably, one of the most sophisticated visual perceptual skills in humans. The organization of neural systems for face perception has stimulated intense debate. This article presents an updated model of distributed human neural systems for face perception. It opens up with a discussion of the Core System for visual analysis of faces with an emphasis on the distinction between perception of invariant features for identity recognition and changeable (...) features for recognition of facial gestures such as expression and eye gaze. The study analyses the roles of systems for the representation of emotion, for person knowledge, and for action understanding in face recognition and perception of expression and gaze. It presents systems that are of particular relevance for social communication and that are illustrative of how distributed systems are engaged by face perception. It concludes with a discussion of modularity and distributed processing in neural representation. (shrink)

Psychophysical experiments have demonstrated large and highly systematic perceptual distortions of tactile space. Such a space can be referred to our experience of the spatial organisation of objects, at representational level, through touch, in analogy with the familiar concept of visual space. We investigated the neural basis of tactile space by analysing activity patterns induced by tactile stimulation of nine points on a 3 × 3 square grid on the hand dorsum using functional magnetic resonance imaging. We used a (...) searchlight approach within pre-defined regions of interests to compute the pairwise Euclidean distances between the activity patterns elicited by tactile stimulation. Then, we used multidimensional scaling to reconstruct tactile space at the neural level and compare it with skin space at the perceptual level. Our reconstructions of the shape of skin space in contralateral primary somatosensory and motor cortices reveal that it is distorted in a way that matches the perceptual shape of skin space. This suggests that early sensorimotor areas critically contribute to the distorted internal representation of tactile space on the hand dorsum. (shrink)

Many studies have discussed the neural basis of asset bubbles. They found that the dorsolateral prefrontal cortex (DLPFC) played an important role in bubble formation, but whether a causal relationship exists and the mechanism of the effect of the DLPFC on bubbles remains unsettled. Using transcranial direct current stimulation (tDCS), we modulated the activity of the DLPFC and investigated the causal relationship between the DLPFC and the asset bubble in the classical learning-to-forecast experiment. 126 subjects were randomly divided into (...) three groups and received different stimulations (left anodal/right cathodal, right anodal/left cathodal or sham stimulation) respectively. We also conducted a 2-back task before and after stimulation to measure changes in subjects’ cognitive abilities and explore in detail the cognitive mechanism of the effect of DLPFC stimulation on asset bubbles. Based on our results, we found that the bubble of the left anodal/right cathodal stimulation group was significantly smaller than that of the sham stimulation group. In the meantime, subjects performed significantly better in the 2-back task after left anodal/right cathodal stimulation but not right anodal/left cathodal or sham stimulation, which is consistent with their performance in the learning-to-forecast experiment, supporting the cognitive mechanism to some extent. Furthermore, we examined different forecasting rules across individuals and discovered that the left anodal/right cathodal stimulation group preferred the adaptive learning rule, while the sham and right anodal/left cathodal stimulation groups adopted a pure trend-following rule that tended to intensify market volatility aggressively. (shrink)

The expansion of research on deep brain stimulation (DBS) and adaptive DBS (aDBS) raises important neuroethics and policy questions related to data sharing. However, there has been little empirical research on the perspectives of experts developing these technologies. We conducted semi-structured, open-ended interviews with aDBS researchers regarding their data sharing practices and their perspectives on ethical and policy issues related to sharing. Researchers expressed support for and a commitment to sharing, with most saying that they were either sharing their data (...) or would share in the future and that doing so was important for advancing the field. However, those who are sharing reported a variety of sharing partners, suggesting heterogeneity in sharing practices and lack of the broad sharing that would reflect principles of open science. Researchers described several concerns and barriers related to sharing, including privacy and confidentiality, the usability of shared data by others, ownership and control of data (including potential commercialization), and limited resources for sharing. They also suggested potential solutions to these challenges, including additional safeguards to address privacy issues, standardization and transparency in analysis to address issues of data usability, professional norms and heightened cooperation to address issues of ownership and control, and streamlining of data transmission to address resource limitations. Researchers also offered a range of views on the sensitivity of neural activity data (NAD) and data related to mental health in the context of sharing. These findings are an important input to deliberations by researchers, policymakers, neuroethicists, and other stakeholders as they navigate ethics and policy questions related to aDBS research. (shrink)

Objective: Caloric vestibular stimulation has traditionally been used as a tool for neurological diagnosis. More recently, however, it has been applied to a range of phenomena within the cognitive neurosciences. Here, we provide an overview of such studies and review our work using CVS to investigate the neural mechanisms of a visual phenomenon - binocular rivalry. We outline the interhemispheric switch model of rivalry supported by this work and its extension to a metarivalry model of interocular-grouping phenomena. In addition, (...) studies showing a slow rate of binocular rivalry in bipolar disorder are discussed, and the relationship between this finding and the interhemispheric switch model is described. We also review the effects of CVS in various clinical contexts, explain how the technique is performed and discuss methodological issues in its application. (shrink)

Rationale: Deep brain stimulation (DBS) of the hippocampus is proposed for enhancement of memory impaired by injury or disease. Many pre-clinical DBS paradigms can be addressed in epilepsy patients undergoing intracranial monitoring for seizure localization, since they already have electrodes implanted in brain areas of interest. Even though epilepsy is usually not a memory disorder targeted by DBS, the studies can nevertheless model other memory-impacting disorders, such as Traumatic Brain Injury (TBI). Methods: Human patients undergoing Phase II invasive monitoring for (...) intractable epilepsy were implanted with depth electrodes capable of recording neurophysiological signals. Subjects performed a delayed-match-to-sample (DMS) memory task while hippocampal ensembles from CA1 and CA3 cell layers were recorded to estimate a multi-input, multi-output (MIMO) model of CA3-to-CA1 neural encoding and a memory decoding model (MDM) to decode memory information from CA3 and CA1 neuronal signals. After model estimation, subjects again performed the DMS task while either MIMO-based or MDM-based patterned stimulation was delivered to CA1 electrode sites during the encoding phase of the DMS trials. Each subject was sorted (post hoc) by prior experience of repeated and/or mild-to-moderate brain injury (RMBI), TBI, or no history (control) and scored for percentage successful delayed recognition (DR) recall on stimulated vs. non-stimulated DMS trials. The subject’s medical history was unknown to the experimenters until after individual subject memory retention results were scored. Results: When examined compared to control subjects, both TBI and RMBI subjects showed increased memory retention in response to both MIMO and MDM-based hippocampal stimulation. Furthermore, effects of stimulation were also greater in subjects who were evaluated as having pre-existing mild-to-moderate memory impairment. Conclusion: These results show that hippocampal stimulation for memory facilitation was more beneficial for subjects who had previously suffered a brain injury (other than epilepsy), compared to control (epilepsy) subjects who had not suffered a brain injury. This study demonstrates that the epilepsy/intracranial recording model can be extended to test the ability of DBS to restore memory function in subjects who previously suffered a brain injury other than epilepsy, and support further investigation into the beneficial effect of DBS in TBI patients. (shrink)

Science fiction is fast becoming reality as scientists and engineers seek to develop new ways of directly accessing and controlling our brains through brain-computer and even brain-to-brain interfaces. If such research is to receive continuing public approval and support—and not invite opposition—it must anticipate the special ethical challenges it creates. By pointing to some of the acute concerns raised by neural engineering technologies—around issues of identity, normality, authority, responsibility, privacy, and justice—Eran Klein and colleagues model and stimulate the kind (...) of reflection that will be needed as new brain technologies are developed. And yet, as I read their informative discussion, I find myself asking even more questions. One concerns the ethical novelty of these technologies. For example, in terms of questions of identity, normality, responsibility, and authority, how different is deep brain stimulation from the potent psychiatric drugs that have been administered for decades? How different in terms of issues of liability associated with malfunction or misuse are brain-computer interfaces from other complex devices now routinely in use? Neither ethics nor law will have to rethink things from scratch as new neural devices and capabilities are introduced: the groundwork for answering some of these questions has already been laid in a variety of fields from bioethics, to health and product liability law. Nevertheless, I conclude that there are new questions here. It is not simply the fact that neural technologies pose questions of identity, privacy, and the like but that they do so with a degree of intensity that creates qualitatively new challenges. (shrink)

Deep brain stimulation (DBS) of the globus pallidus interna and subthalamic nucleus has restored some degree of motor control in many patients in advanced stages of Parkinson’s disease. DBS has also been used to treat dystonia, essential tremor (progressive neurological condition causing trembling), chronic pain, obsessive-compulsive disorder, Tourette’s syndrome, major depressive disorder, obesity, cerebral palsy, and the minimally conscious state. Although the underlying mechanisms of the technique are still not clear, DBS can modulate underactive or overactive neural circuits and (...) restore disrupted communication between and among groups of neurons in interacting regions of the brain. This can control and relieve many symptoms associated with a range of neurological and psychiatric disorders.But the procedures of implanting and stimulating the electrodes are brain-invasive and entail significant risks. Some patients receiving DBS have experienced intracerebral hemorrhage, infection, cognitive disturbances such as impulsive behavior, and affective disturbances such as mania. It is not known whether continuous electrical stimulation of the brain would reshape synaptic connectivity and permanently alter neural circuits in ways that may not be salutary. The risk of these effects indicates that DBS should be used only when a patient’s condition is refractory to all other interventions and when there is a high probability that the technique will benefit the patient and improve his or her quality of life. If a patient’s quality of life is poor and all other treatment options have been exhausted, then the likelihood of benefit can justify physicians’ exposing patients to some risk. The clinical and ethical significance of the risk in DBS underscores the obligation of physicians to obtain fully informed consent from patients undergoing the procedure. (shrink)

Deep Brain Stimulation is currently being investigated as an experimental treatment for patients suffering from treatment-refractory AN, with an increasing number of case reports and small-scale trials published. Although still at an exploratory and experimental stage, initial results have been promising. Despite the risks associated with an invasive neurosurgical procedure and the long-term implantation of a foreign body, DBS has a number of advantageous features for patients with SE-AN. Stimulation can be fine-tuned to the specific needs of the particular patient, (...) is relatively reversible, and the technique also allows for the crucial issue of investigating and comparing the effects of different neural targets. However, at a time when DBS is emerging as a promising investigational treatment modality for AN, lesioning procedures in psychiatry are having a renaissance. Of concern it has been argued that the two kinds of interventions should instead be understood as rivaling, yet “mutually enriching paradigms” despite the fact that lesioning the brain is irreversible and there is no evidence base for an effective target in AN. We argue that lesioning procedures in AN are unethical at this stage of knowledge and seriously problematic for this patient group, for whom self-control is particularly central to wellbeing. They pose a greater risk of major harms that cannot justify ethical equipoise, despite the apparent superiority in reduced short term surgical harms and lower cost. (shrink)

'Brainjacking’ refers to the exercise of unauthorized control of another’s electronic brain implant. Whilst the possibility of hacking a Brain–Computer Interface (BCI) has already been proven in both experimental and real-life settings, there is reason to believe that it will soon be possible to interfere with the software settings of the Implanted Pulse Generators (IPGs) that play a central role in Deep Brain Stimulation (DBS) systems. Whilst brainjacking raises ethical concerns pertaining to privacy and physical or psychological harm, we claim (...) that the possibility of brainjacking DBS raises particularly profound concerns about individual autonomy, since the possibility of hacking such devices raises the prospect of third parties exerting influence over the neural circuits underpinning the subject’s cognitive, emotional and motivational states. However, although it seems natural to assume that brainjacking represents a profound threat to individual autonomy, we suggest that the implications of brainjacking for individual autonomy are complicated by the fact that technologies targeted by brainjacking often serve to enhance certain aspects of the user’s autonomy. The difficulty of ascertaining the implications of brainjacking DBS for individual autonomy is exacerbated by the varied understandings of autonomy in the neuroethical and philosophical literature. In this paper, we seek to bring some conceptual clarity to this area by mapping out some of the prominent views concerning the different dimension of autonomous agency, and the implications of brainjacking DBS for each dimension. Drawing on three hypothetical case studies, we show that there could plausibly be some circumstances in which brainjacking could potentially be carried out in ways that could serve to enhance certain dimensions of the target’s autonomy. Our analysis raises further questions about the power, scope, and necessity of obtaining prior consent in seeking to protect patient autonomy when directly interfering with their neural states, in particular in the context of self-regulating closed-loop stimulation devices. (shrink)

The essential role of creativity has been highlighted in several human knowledge areas. Regarding the neural underpinnings of creativity, there is evidence about the role of left dorsolateral prefrontal cortex (DLPFC) and left inferior frontal gyrus (IFG) on divergent thinking (DT) and convergent thinking (CT). Transcranial stimulation studies suggest that the left DLPFC is associated with both DT and CT, whereas left IFG is more related to DT. However, none of the previous studies have targeted both hubs simultaneously and (...) compared transcranial direct current stimulation (tDCS) and random noise stimulation (tRNS). Additionally, given the relationship between cognitive flexibility and creativity, we included it in order to check if the improvement in creativity may be mediated by cognitive flexibility. In this double-blind, between-subjects study, 66 healthy participants were randomly assigned to one of three groups (N = 22) that received a transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS), or sham for 20 min. The tDCS group received 1.5 mA with the anode over the left DLPFC and cathode over the left IFG. Locations in tRNS group were the same and they received 1.5 mA of high frequency tRNS (100–500 Hz). Divergent thinking was assessed before (baseline) and during stimulation with unusual uses (UU) and picture completion (PC) subtests from Torrance Creative thinking Test, whereas convergent thinking was evaluated with the remote association test (RAT). Stroop test was included to assess cognitive flexibility. ANCOVA results of performance under stimulation (controlling for baseline performance) showed that there were significant differences in PC (F = 3.35, p = 0.042, np2 = 0.10) but not in UU (F = 0.61, p = 0.546) and RAT (F = 2.65, p = 0.079) scores. Post-hoc analyses showed that tRNS group had significantly higher scores compared to sham (p = 0.004) in PC. More specifically, tRNS showed higher performance in fluency (p = 0.012) and originality (p = 0.021) dimensions of PC compared to sham. Regarding cognitive flexibility, we did not find any significant effect of any of the stimulation groups (F = 0.34, p = 0.711). Therefore, no further mediation analyses were performed. Finally, the group that received tDCS reported more adverse effects than sham group (F = 3.46, p = 0.035). Altogether, these results suggest that tRNS may have some advantages over tDCS in DT. (shrink)

The model developed in the target article is not as comprehensive as might be desired on two counts: (1) in that how the transition from proximal stimulation at the skin gives rise to the perception of external objects is taken for granted; and (2) in that another population of participants, the blind, constitute an important group from which we can understand somatosensory processing and neural plasticity.

Transcranial magnetic stimulation (TMS) is a method capable of transiently modulating neural excitability. Depending on the stimulation parameters information processing in the brain can be either enhanced or disrupted. This way the contribution of different brain areas involved in mental processes can be studied, allowing a functional decomposition of cognitive behavior both in the temporal and spatial domain, hence providing a functional resolution of brain/mind processes. The aim of the present paper is to argue that TMS with its ability (...) to draw causal inferences on function and its neural representations is a valuable neurophysiological tool for investigating the causal basis of neuronal functions and can provide substantive insight into the modern interdisciplinary and (anti)reductionist neurophilosophical debates concerning the relationships between brain functions and mental abilities. Thus, TMS can serve as a heuristic method for resolving causal issues in an arena where only correlative tools have traditionally been available. (shrink)

In order to study whether there exist a period of activity in the human early visual cortex that contributes exclusively to visual awareness, we applied transcranial magnetic stimulation over the early visual cortex and measured subjective visual awareness during visual forced-choice symbol or orientation discrimination tasks. TMS produced one dip in awareness 60–120 ms after stimulus onset, while forced-choice orientation discrimination was suppressed between 60 and 90 ms and symbol discrimination between 60 and 120 ms. Thus, a time window specific (...) to visual awareness was found only in the orientation condition at 120 ms. The results imply that both conscious and unconscious perception depend on activity in early visual areas. On the basis of previous estimates of neural processing speed, we suggest that the late part of the activity period most likely involve local extrastriate–striate interactions which provide the contents for visual awareness but are not themselves sufficient for awareness to arise. (shrink)

Transcranial magnetic stimulation (TMS) is a method capable of transiently modulating neural excitability. Depending on the stimulation parameters information processing in the brain can be either enhanced or disrupted. This way the contribution of different brain areas involved in mental processes can be studied, allowing a functional decomposition of cognitive behavior both in the temporal and spatial domain, hence providing a functional resolution of brain/mind processes. The aim of the present paper is to argue that TMS with its ability (...) to draw causal inferences on function and its neural representations is a valuable neurophysiological tool for investigating the causal basis of neuronal functions and can provide substantive insight into the modern interdisciplinary and (anti)reductionist neurophilosophical debates concerning the relationships between brain functions and mental abilities. Thus, TMS can serve as a heuristic method for resolving causal issues in an arena where only correlative tools have traditionally been available. (shrink)

Deep brain stimulation of the subthalamic nucleus is an effective treatment for the motor symptoms of movement disorders including Parkinson's Disease. Despite its therapeutic benefits, STN-DBS has been associated with adverse effects on mood and cognition. Specifically, apathy, which is defined as a loss of motivation, has been reported to emerge or to worsen following STN-DBS. However, it is often challenging to disentangle the effects of STN-DBSper sefrom concurrent reduction of dopamine replacement therapy, from underlying PD pathology or from disease (...) progression. To this end, pre-clinical models allow for the dissociation of each of these factors, and to establish neural substrates underlying the emergence of motivational symptoms following STN-DBS. Here, we performed a systematic analysis of rodent studies assessing the effects of STN-DBS on reward seeking, reward motivation and reward consumption across a variety of behavioral paradigms. We find that STN-DBS decreases reward seeking in the majority of experiments, and we outline how design of the behavioral task and DBS parameters can influence experimental outcomes. While an early hypothesis posited that DBS acts as a “functional lesion,” an analysis of lesions and inhibition of the STN revealed no consistent pattern on reward-related behavior. Thus, we discuss alternative mechanisms that could contribute to the amotivational effects of STN-DBS. We also argue that optogenetic-assisted circuit dissection could yield important insight into the effects of the STN on motivated behavior in health and disease. Understanding the mechanisms underlying the effects of STN-DBS on motivated behavior-will be critical for optimizing the clinical application of STN-DBS. (shrink)

Michael Pardo and Dennis Patterson have recently put forward several provocative and stimulating criticisms that strike at the heart of much work that has been done at the crossroads of neuroscience and the law. My goal in this essay is to argue that their criticisms of the nascent but growing field of neurolaw are ultimately based on questionable assumptions concerning the nature of the ever evolving relationship between scientific discovery and ordinary language. For while the marriage between ordinary language and (...) scientific discovery is admittedly not always a happy one, it is an awkward union that nevertheless seems to work itself out with the passage of time. In the following pages, I will try to show that Pardo and Patterson’s primary argumentative strategy ultimately depends on basic assumptions concerning the fixity of language that we should reject. (shrink)

Self-enhancement is the biasing of one’s view of oneself in a positive direction. The brain correlates of self-enhancement remain unclear though it has been reported that the medial prefrontal cortex may be important for producing self-enhancing responses. Previous studies have not examined whether the neural correlates of self-enhancement depend on the particular domain in which individuals are enhancing themselves. Both moralistic and egoistic words were presented to participants while transcranial magnetic stimulation was applied to the MPFC, precuneus or in (...) a sham orientation. Participants were asked to make decisions as to the words describing themselves, some of which were positive and some of which were negative. It was found the MPFC TMS significantly disrupted egoistic self-enhancement when TMS was delivered to the MPFC. Judgments involving moralistic words were not influenced by TMS. These data provide further evidence that MPFC is involved in self-enhancement, and that the role of MPFC may be selective in this regard. (shrink)

Social norms play an essential role in human interactions and the development of the evolution of human history. Extensive studies corroborate that compliance with social norms typically requires a punishment threat as almost always specific individuals have self-interests that tempt them to violate the norm. Neural imaging studies demonstrate that lateral orbitofrontal cortex and right dorsolateral prefrontal cortex (rDLPFC) are activated when individuals decide to increase social norm compliance when punishment is possible. Moreover, rDLPFC is affirmed to be involved (...) in social norm compliance with or without external punishment threats in a series of transcranial direct current stimulation (tDCS) research. However, these neuroscience studies are based on the ultimatum game in which the decision-making power between the proposer and the responder is unequal, and no studies support the causal relationship between rDLPFC and voluntary cooperative norms compliance among the equal decision-making power of subjects. Whether modulating the excitability of rDLPFC, which plays a role in norm compliance, alters the extent of compliance with voluntary cooperative norms under equal decision-making power and how norms from different types with asymmetric endowment influence compliance remain unknown. The present study aimed to provide evidence of a direct link between the neural and behavioral results through the application of tDCS over rDLPFC on compliance with voluntary cooperative norms under equal decision-making power. Results verified that activating rDLPFC altered voluntary cooperative norms compliance of all our participants and significant effect over different initial endowments was observed. The role of norm.own and norm.other in compliance was changed in the anodal treatment. Findings validate that enhancing the excitability of the rDLPFC using tDCS leads to high compliance in voluntary cooperation and this effect is specific to equal decision-making power rather than unequal decision-making power. (shrink)

Transvertebral magnetic stimulation (TVMS) of the human lumbar spinal cord can evoke bilateral rhythmic leg movements, as in walking, supposedly through the activation of spinal locomotor neural circuitry. However, an appropriate stimulus intensity that can effectively drive the human spinal locomotor circuitry to evoke walking-like movements has not been determined. To address this issue, TVMS was delivered over an intervertebral space of the lumbar cord (L1–L3) at different stimulus intensities (10–70% of maximum stimulator output) in healthy human adults. (...) In a stimulus intensity-dependent manner, TVMS evoked two major patterns of rhythmic leg movements in which the left-right movement cycles were coordinated with different phase relationships: hopping-like movements, in which both legs moved in the same direction in phase, and walking-like movements, in which both legs moved alternatively in anti-phase; uncategorized movements were also observed which could not be categorized as either movement type. Even at the same stimulation site, the stimulus-evoked rhythmic movements changed from hopping-like movements to walking-like movements as stimulus intensity was increased. Different leg muscle activation patterns were engaged in the induction of the hopping- and walking-like movements. The magnitude of the evoked hopping- and walking-like movements was positively correlated with stimulus intensity. The human spinal neural circuitry required a higher intensity of magnetic stimulation to produce walking-like leg movements than to produce hopping-like movements. These results suggest that TVMS activates distinct neural modules in the human spinal cord to generate hopping- and walking-like movements. (shrink)

Ethical analyses of the effects of neural interventions commonly focus on changes to personality and behavior, interpreting these changes in terms of authenticity and identity. These phenomena have led to debate among ethicists about the meaning of these terms for ethical analysis of such interventions. While these theoretical approaches have different criteria for ethical significance, they agree that patients’ reports are concerning because a sense of self is valuable. In this paper, I question this assumption. I propose that the (...) Buddhist theory of no‐self offers a novel approach to making ethical sense of patients’ claims following deep brain stimulation. This alternative approach is based on the value of insight into patterns of cause and effect among mental states and actions. (shrink)

We examined the neural basis of tactile distance perception by analyzing activity patterns induced by tactile stimulation of nine points on a 3 x 3 square grid on the hand dorsum using functional magnetic resonance (fMRI). We used a searchlight approach within pre-defined regions of interests (ROIs) to compute the pairwise Euclidean distances between the activity patterns elicited by tactile stimulation. Then, we used multidimensional scaling (MDS) to reconstruct skin space at the neural level and compare it with (...) skin space at the perceptual level. Our reconstructions of the shape of skin space in contralateral primary somatosensory (SI) and motor (M1) cortices reveal that it is distorted in a way that matches the perceptual shape of skin space. This suggests that early sensorimotor areas are critical to processing tactile distance perception. (shrink)

When we judge an action as morally right or wrong, we rely on our capacity to infer the actor's mental states. Here, we test the hypothesis that the right temporoparietal junction, an area involved in mental state reasoning, is necessary for making moral judgments. In two experiments, we used transcranial magnetic stimulation to disrupt neural activity in the RTPJ transiently before moral judgment and during moral judgment. In both experiments, TMS to the RTPJ led participants to rely less on (...) the actor's mental states. A particularly striking effect occurred for attempted harms : Relative to TMS to a control site, TMS to the RTPJ caused participants to judge attempted harms as less morally forbidden and more morally permissible. Thus, interfering with activity in the RTPJ disrupts the capacity to use mental states in moral judgment, especially in the case of attempted harms. (shrink)

A central debate in philosophy and neuroscience pertains to whether PFC activity plays an essential role in the neural basis of consciousness. Neuroimaging and electrophysiology studies have revealed that the contents of conscious perceptual experience can be successfully decoded from PFC activity, but these findings might be confounded by post- perceptual cognitive processes, such as thinking, reasoning, and decision-making, that are not necessary for con- sciousness. To clarify the involvement of the PFC in consciousness, we present a synthesis of (...) research that has used intracranial electrical stimulation (iES) for the causal modulation of neural activity in the human PFC. This research provides compelling evidence that iES of only certain prefrontal regions (i.e., orbitofrontal cortex and anterior cingu- late cortex) reliably perturbs conscious experience. Conversely, stimulation of anterolateral prefrontal sites, often con- sidered crucial in higher-order and global workspace theories of consciousness, seldom elicits any reportable alterations in consciousness. Furthermore, the wide variety of iES-elicited effects in the PFC (e.g., emotions, thoughts, and olfactory and visual hallucinations) exhibits no clear relation to the immediate environment. Therefore, there is no evidence for the kinds of alterations in ongoing perceptual experience that would be predicted by higher-order or global workspace theories. Nevertheless, effects in the orbitofrontal and anterior cingulate cortices suggest a specific role for these PFC subregions in supporting emotional aspects of conscious experience. Overall, this evidence presents a challenge for higher-order and global workspace theories, which commonly point to the PFC as the basis for con- scious perception based on correlative and possibly confounded information. (shrink)

Neural engineering technologies such as implanted deep brain stimulators and brain-computer interfaces represent exciting and potentially transformative tools for improving human health and well-being. Yet their current use and future prospects raise a variety of ethical and philosophical concerns. Devices that alter brain function invite us to think deeply about a range of ethical concerns—identity, normality, authority, responsibility, privacy, and justice. If a device is stimulating my brain while I decide upon an action, am I still the author of (...) the action? Does a device make the interiority of my experience accessible to others? Will the device change the way I think of myself and others think of me? Such fundamental questions arise even when a device is designed for only a relatively circumscribed purpose, such as restoring functioning via a smart prosthetic. We are part of a National Science Foundation-funded Engineering Research Center tasked with investigating philosophical and social implications of neural engineering research and technologies. Neural devices already in clinical use, such as deep brain stimulators for Parkinson's disease or essential tremor, have spurred healthy debate about such implications. Devices currently under development—such as the BrainGate System of implanted brain sensors coupled to robotics in persons with paralysis, exoskeletons for augmented movement, transcranial do-it-yourself stimulators, closed-loop brain stimulating systems, or even brain-to-brain interfacing—promise to extend and deepen these debates. At our center, brain-computer interfaces are the principal focus of work. Even acknowledging that the clinical translation of neural devices and seamless integration by end users may still largely reside in the future, the potential these devices hold calls for careful early analysis. The launching of the Brain Research through Advancing Innovative Neurotechnologies Initiative in April 2013 provides further impetus for this work. (shrink)

The profound changes in personality, mood, and other features of the self that neural interventions can induce can be disconcerting to patients, their families, and caregivers. In the neuroethical debate, these concerns are often addressed in the context of possible threats to the narrative self. In this paper, I argue that it is necessary to consider a dimension of impacts on the narrative self which has so far been neglected: neural interventions can lead to a loss of meaning (...) of actions, feelings, beliefs, and other intentional elements of our self-narratives. To uphold the coherence of the self-narrative, the changes induced by neural interventions need to be accounted for through explanations in intentional or biochemical terms. However, only an explanation including intentional states delivers the content to directly ascribe personal meaning, i.e., subjective value to events. Neural interventions can deprive events of meaning because they may favor a predominantly biochemical account. A loss of meaning is not inherently negative but it can be problematic, particularly if events are affected one was not prepared or willing to have stripped of meaning. The paper further examines what it is about neural interventions that impacts meaning by analyzing different methods. To which degree the pull towards a biochemical view occurs depends on the characteristics of the neural intervention. By comparing Deep Brain Stimulation, Prozac, Ritalin, psychedelics, and psychotherapy, the paper identifies some main factors: the rate of change, the transparency of the causal chain, the involvement of the patient, and the presence of an acute phenomenological experience. (shrink)

We estimate that 208,000 deep brain stimulation (DBS) devices have been implanted to address neurological and neuropsychiatric disorders worldwide. DBS Think Tank presenters pooled data and determined that DBS expanded in its scope and has been applied to multiple brain disorders in an effort to modulate neural circuitry. The DBS Think Tank was founded in 2012 providing a space where clinicians, engineers, researchers from industry and academia discuss current and emerging DBS technologies and logistical and ethical issues facing the (...) field. The emphasis is on cutting edge research and collaboration aimed to advance the DBS field. The Eighth Annual DBS Think Tank was held virtually on September 1 and 2, 2020 (Zoom Video Communications) due to restrictions related to the COVID-19 pandemic. The meeting focused on advances in: (1) optogenetics as a tool for comprehending neurobiology of diseases and on optogenetically-inspired DBS, (2) cutting edge of emerging DBS technologies, (3) ethical issues affecting DBS research and access to care, (4) neuromodulatory approaches for depression, (5) advancing novel hardware, software and imaging methodologies, (6) use of neurophysiological signals in adaptive neurostimulation, and (7) use of more advanced technologies to improve DBS clinical outcomes. There were 178 attendees who participated in a DBS Think Tank survey, which revealed the expansion of DBS into several indications such as obesity, post-traumatic stress disorder, addiction and Alzheimer’s disease. This proceedings summarizes the advances discussed at the Eighth Annual DBS Think Tank. (shrink)

Backgrounds: Transcranial direct current stimulation is a non-invasive brain stimulation technique for the treatment of several psychiatric disorders, e.g., mood disorders and schizophrenia. Therapeutic effects of tDCS are suggested to be produced by bi-directional changes in cortical activities, i.e., increased/decreased cortical excitability via anodal/cathodal stimulation. Although tDCS provides a promising approach for the treatment of psychiatric disorders, its neurobiological mechanisms remain to be explored.Objectives: To review recent findings from neurophysiological, chemical, and brain-network studies, and consider how tDCS ameliorates psychiatric conditions.Findings: (...) Enhancement of excitatory synaptic transmissions through anodal tDCS stimulation is likely to facilitate glutamate transmission and suppress gamma-aminobutyric acid transmission in the cortex. On the other hand, it positively or negatively modulates the activities of dopamine, serotonin, and acetylcholine transmissions in the central nervous system. These neural events by tDCS may change the balance between excitatory and inhibitory inputs. Specifically, multi-session tDCS is thought to promote/regulate information processing efficiency in the cerebral cortical circuit, which induces long-term potentiation by synthesizing various proteins.Conclusions: This review will help understand putative mechanisms underlying the clinical benefits of tDCS from the perspective of neurotransmitters, network dynamics, intracellular events, and related modalities of the brain function. (shrink)

Visual stimuli as well as transcranial magnetic stimulation can be used: to suppress the visibility of a target and to recover the visibility of a target that has been suppressed by another mask. Both types of stimulation thus provide useful methods for studying the microgenesis of object perception. We first review evidence of similarities between the processes by which a TMS mask and a visual mask can either suppress the visibility of targets or recover such suppressed visibility. However, we then (...) also point out a significant difference that has important implications for the study of the time course of unconscious and conscious visual information processing and for theoretical accounts of the processes involved. We present evidence and arguments showing: that visual masking techniques, by revealing more detailed aspects of target masking and target recovery, support a theoretical approach to visual masking and visual perception that must take into account activities in two separate neural channels or processing streams and, as a corollary, that at the current stage of methodological sophistication visual masks, by acting in more highly specifiable ways on these pathways, provide information about the microgenesis of form perception not available with TMS masks. (shrink)

According to a prominent suggestion in the ethics of transcranial neurostimulation the effects of such devices can be treated as ethically on par with established, pre-neurotechnological alterations of the mind. This parity allegedly is supported by situated cognition theories showing how external devices can be part of a cognitive system. This article will evaluate this suggestion. It will reject the claim, that situated cognition theories support ethical parity. It will however point out another reason, why external carriers or modifications of (...) the mental might come to be considered ethically on par with internal carriers. Section “Why Could There Be Ethical Parity between Neural Tissue and External Tools?” presents the ethical parity theses between external and internal carriers of the mind as well as neurotechnological alterations and established alterations. Section “Extended, Embodied, Embedded: Situated Cognition as a Relational Thesis” will elaborate the different situated cognition approaches and their relevance for ethics. It will evaluate, whether transcranial stimulation technologies are plausible candidates for situated cognition theses. Section “On the Ethical Relevance of Situated Cognition Theses” will discuss criteria for evaluating whether a cognitive tool is deeply embedded with a cognitive system and apply these criteria to transcranial brain stimulation technologies. Finally it will discuss the role diverse versions of situated cognition theory can play in the ethics of altering mental states, especially the ethics of transcranial brain stimulation technologies. (shrink)