Neural Timing and Consciousness

The purpose of this paper is to address a well-known dilemma for physicalism. If mental properties are type identical to physical properties, then their causal efficacy is secure, but at the cost of ruling out mentality in creatures very different to ourselves. On the other hand, if mental properties are multiply realizable, then all kinds of creatures can instantiate them, but then they seem to be causally redundant. The causal exclusion problem depends on the widely held principle that realized properties (...) inherit their causal powers from their realizers. While this principle holds for functional realization, it fails on a broader notion of realization that permits the realization of complex qualitative properties such as spatial and temporal patterns. Such properties are best seen as dependent powerful qualities, which have their causal roles in virtue of being the qualities they are, and do not inherit powers from their realizers. Recent studies have identified one such property—neural synchrony—as a correlate of consciousness. If synchrony is also partially constitutive of consciousness, then phenomenal properties are both multiply realizable and causally novel. I outline a version of representationalism about consciousness on which this constitution claim holds. (shrink)

By reviewing most of the neurobiology of consciousness, this article highlights some major reasons why a successful emulation of the dynamics of human consciousness by artificial intelligence is unlikely. The analysis provided leads to conclude that human consciousness is epigenetically determined and experience and context-dependent at the individual level. It is subject to changes in time that are essentially unpredictable. If cracking the code to human consciousness were possible, the result would most likely have to consist of a temporal pattern (...) code simulating long-distance signal reverberation and de-correlation of all spatial signal contents from temporal signals. In the light of the massive evidence for complex interactions between implicit (non-conscious) and explicit (conscious) contents of representation, the code would have to be capable of making implicit (non-conscious) processes explicit. It would have to be capable of a progressively less and less arbitrary selection of temporal activity patterns in a continuously developing neural network structure identical to that of the human brain, from the synaptic level to that of higher cognitive functions. The code’s activation thresholds would depend on specific temporal signal coincidence probabilities, vary considerably with time and across individual experience data, and would therefore require dynamically adaptive computations capable of emulating the properties of individual human experience. No known machine or neural network learning approach has such potential. (shrink)

The target paper of Schoeller, Perlovsky, and Arseniev is an essential and timely contribution to a current shift of focus in neuroscience aiming to merge neurophysiological, psychological and physical principles in order to build the foundation for the physics of mind. Extending on previous work of Perlovsky et al. and Badre, the authors of the target paper present interesting mathematical models of several basic principles of the physics of mind, such as perception and cognition, concepts and emotions, instincts and learning. (...) Their conceptualization helps to clarify the distinction between conscious and unconscious aspects of mind that is often neglected and further provide a clear description of the mental hierarchy, which extends from physical objects in the physical world to abstract ideas in the mental/subjective realm. While we agree that identification of a few fundamental principles is a first step toward developing the physics of the mind, and we concur with the selection of those principles in the target review paper, we think that the theory of the physics of mind would much benefit from considering also the most basic principles that are common for the physics/matter/brain and the mind/subjectivity/cognition. In this respect, such basic principles as time and space, as well as criticality, self-organization, and emergence seem to be the most interesting. (shrink)

The brain displays both the anatomical features of a vast amount of interconnected topological mappings as well as the functional features of a nonlinear, metastable system at the edge of chaos, equipped with a phase space where mental random walks tend towards lower energetic basins. Nevertheless, with the exception of some advanced neuro-anatomic descriptions and present-day connectomic research, very few studies have been addressing the topological path of a brain embedded or embodied in its external and internal environment. Herein, by (...) using new formal tools derived from algebraic topology, we provide an account of the metastable brain, based on the neuro-scientific model of Operational Architectonics of brain-mind functioning. We introduce a “topodynamic” description that shows how the relationships among the countless intertwined spatio-temporal levels of brain functioning can be assessed in terms of projections and mappings that take place on abstract structures, equipped with different dimensions, curvatures and energetic constraints. Such a topodynamical approach, apart from providing a biologically plausible model of brain function that can be operationalized, is also able to tackle the issue of a long-standing dichotomy: it throws indeed a bridge between the subjective, immediate datum of the naïve complex of sensations and mentations and the objective, quantitative, data extracted from experimental neuro-scientific procedures. Importantly, it opens the door to a series of new predictions and future directions of advancement for neuroscientific research. (shrink)

How do separate brain processes bind to form unified, conscious percepts? This is the perceptual binding problem, which straddles neuroscience and psychology. In fact, two problems exist here: (1) the easy problem of how neural processes are unified, and (2) the hard problem of how this yields unified perceptual consciousness. Binding theories face familiar troubles with (1) and they do not come to grips with (2). This paper argues that neuroelectrical (electromagnetic-field) approaches may help with both problems. Concerning the easy (...) problem, standard accounts of neural binding by synchrony, attention, and convergence raise serious difficulties. These are avoided by neuroelectrical approaches in which the brain’s field binds distributed processes in myriad neurons. Concerning the hard problem, binding theories do not squarely address how to get from neural unity to unified consciousness. This raises metaphysical difficulties involving reductions, emergence, etc. Neuroelectrical (and Russellian) approaches may help avoid these difficulties too. These approaches may thus deserve further investigation as binding theories. (shrink)

Despite the fact that attention is a core property of all perceptual and cognitive operations, our understanding of its neurophysiological mechanisms is far from complete. There are many theoretical models that try to fill this gap in knowledge, though practically all of them concentrate only on either involuntary (bottom-up) or voluntarily (top-down) aspect of attention. At the same time, both aspects of attention are rather integrated in the living brain. In this chapter we attempt to conceptualise both aspects of attentional (...) state within the theory of Operational Architectonics of brain and mind functioning, which provides a plausible theoretical basis for neurophysiological understanding of how attention is brought to existence in the living brain. (shrink)

http://www.sciencedirect.com/science/article/pii/S1053810015002378 -/- the original Fig. 4B published in this paper was incorrect.

It is the every person's daily phenomenal experience that conscious states represent their contents as occurring now. Following Droege (2009) we could state that consciousness has a peculiar affinity for presence. Some researchers even argue that conscious awareness necessarily demands that mental content is somehow held “frozen” within a discrete progressive present moment. Thus, phenomenal content seems to be minimally conscious if it is integrated into a single and coherent model of reality during a “virtual window” of presence.

In this paper we aim to show that phenomenal consciousness is realized by a particular level of brain operational organization and that understanding human consciousness requires a description of the laws of the immediately underlying neural collective phenomena, the nested hierarchy of electromagnetic fields of brain activity – operational architectonics. We argue that the subjective mental reality and the objective neurobiological reality, although seemingly worlds apart, are intimately connected along a unified metastable continuum and are both guided by the universal (...) laws of the physical world such as criticality, self-organization and emergence. (shrink)

In recent times we have seen an explosion in the amount of attention paid to the conscious brain from scientists and philosophers alike. One message that has emerged loud and clear from scientific work is that the brain is a dynamical system whose operations unfold in time. Any theory of consciousness that is going to be physically realistic must take account of the intrinsic nature of neurons and brain activity. At the same time a long discussion on consciousness among philosophers (...) has resulted in our distinguishing several kinds of consciousness. So when we ask where the place of consciousness is in nature we may mean several different things. In this chapter I will argue that it is plausible that all of the kinds of consciousness turn out to be nothing but patterns of synchronized neural activity in various frequencies against a dynamically changing chemical background. (shrink)

The chapters comprising this book represent a collective attempt on the part of their authors to redress this aberration.

This study investigated the differences between past and future temporal discounting in terms of neural activity in relation to temporal distance. Results show that brain regions are engaged differently in past and future temporal discounting. This is likely because past temporal discounting requires memory reconstruction, whereas future temporal discounting requires the processing of uncertainty about the future. In past temporal discounting, neural activity differed only when preferences were made between rewards received one hour prior and rewards received further in the (...) past. The peak amplitudes of P2 and P3 varied as the temporal distance increased from 2 weeks to 50 years. In future temporal discounting, neural activity differed only when preferences were evaluated between two delayed rewards. The delay conditions and had a significant influence on P2 and N2. Findings indicate the existence of different decision-making systems operating in past and future temporal discounting. (shrink)

In timing perception studies, the timing of one event is usually manipulated relative to another, and participants are asked to judge if the two events were synchronous, or to judge which of the two events occurred first. Responses are analyzed to determine a measure of central tendency, which is taken as an estimate of the timing at which the two events are perceptually synchronous. When these estimates do not coincide with physical synchrony, it is often assumed that the sensory signals (...) are asynchronous, as though the transfer of information concerning one input has been accelerated or decelerated relative to the other. Here we show that, while this is a viable interpretation, it is equally plausible that such effects are driven by shifts in the criteria used to differentiate simultaneous from asynchronous inputs. Our analyses expose important ambiguities concerning the interpretation of simultaneity judgement data, which have hitherto been underappreciated. (shrink)

A commentary is given on Trevena and Miller . The comparability of their experimental task and of the potential they recorded with those used and recorded by Libet, Gleason, Wright, and Pearl is questioned. An interpretation is given for the similarity of event-related potentials recorded when subjects decided to move and when they decided not to move.

Benjamin Libet has argued that electrophysiological signs of cortical movement preparation are present before people report having made a conscious decision to move, and that these signs constitute evidence that voluntary movements are initiated unconsciously. This controversial conclusion depends critically on the assumption that the electrophysiological signs recorded by Libet, Gleason, Wright, and Pearl are associated only with preparation for movement. We tested that assumption by comparing the electrophysiological signs before a decision to move with signs present before a decision (...) not to move. There was no evidence of stronger electrophysiological signs before a decision to move than before a decision not to move, so these signs clearly are not specific to movement preparation. We conclude that Libet’s results do not provide evidence that voluntary movements are initiated unconsciously. (shrink)

We report two experiments in which participants had to judge the time of occurrence of a stimulus relative to a clock. The experiments were based on the control condition used by Libet, Gleason, Wright, and Pearl [Libet, B., Gleason, C. A., Wright, E. W., & Pearl, D. K. . Time of conscious intention to act in relation to onset of cerebral activities : The unconscious initiation of a freely voluntary act. Brain 106, 623–642] to correct for any bias in the (...) estimation of the time at which an endogenous event, the conscious intention to perform a movement, occurred. Participants’ responses were affected systematically by the sensory modality of the stimulus and by the speed of the clock. Such findings demonstrate the variability in judging the time at which an exogenous event occurs and, by extension, suggest that such variability may also apply to the judging the time of occurrence of endogenous events. The reliability of participants’ estimations of when they formed the conscious intention to perform a movement in Libet et al.’s study is therefore questionable. (shrink)

We report two experiments in which participants had to judge the time of occurrence of a stimulus relative to a clock. The experiments were based on the control condition used by Libet, Gleason, Wright, and Pearl [Libet, B., Gleason, C. A., Wright, E. W., & Pearl, D. K. . Time of conscious intention to act in relation to onset of cerebral activities : The unconscious initiation of a freely voluntary act. Brain 106, 623–642] to correct for any bias in the (...) estimation of the time at which an endogenous event, the conscious intention to perform a movement, occurred. Participants’ responses were affected systematically by the sensory modality of the stimulus and by the speed of the clock. Such findings demonstrate the variability in judging the time at which an exogenous event occurs and, by extension, suggest that such variability may also apply to the judging the time of occurrence of endogenous events. The reliability of participants’ estimations of when they formed the conscious intention to perform a movement in Libet et al.’s study is therefore questionable. (shrink)

After a lecture in Göteborg by the neuroscientist Benjamin Libet in 1993, the Göteborg-Post carried the headline, ‘Now it has been proven: we are all somewhat behind’. The paper was referring to Libet’s celebrated discovery that the neural precursors of some voluntary actions occur before the conscious awareness of the decision to act. In a series of experiments in the 1980s, Libet showed that in an experimental situation in which subjects were asked to perform a simple voluntary action – raising (...) a finger – these acts were preceded by a rise in electrical activity in the area of the brain responsible for the causation of action, called the ‘readiness potential’ (RP). But the striking discovery is that while the RP is activated 550 msec before the action, the subject’s awareness of their decision to act occurs only 150-200 msec before the action. The conclusion is drawn that the causes of our actions in our brains occur fractionally earlier than our conscious awareness of deciding to do them. Hence the frequent description of the result of Libet’s experiments, that we are ‘living in the past’. (shrink)

This article provides an overview of recent developments in solving the timing problem (discreteness vs. continuity) in cognitive neuroscience. Both theoretical and empirical studies have been considered, with an emphasis on the framework of Operational Architectonics (OA) of brain functioning (Fingelkurts and Fingelkurts, 2001, 2005). This framework explores the temporal structure of information flow and interarea interactions within the network of functional neuronal populations by examining topographic sharp transition processes in the scalp EEG, on the millisecond scale. We conclude, based (...) on the OA framework, that brain functioning is best conceptualized in terms of continuity-discreteness unity which is also the characteristic property of cognition. At the end we emphasize where one might productively proceed for the future research. (shrink)

In this “Reply” paper, the arguments and experimental findings by Pockett, Pollen, and Haggard et al. are analyzed. It had been shown that a 0.5 s duration of repetitive activations of sensory cortex is required to produce a threshold of sensation. The view that this is due to a facilitatory buildup in excitatory state to finally elicit neuronal firing is shown to be incompatible with several lines of evidence. Objections to the phenomenon of subjective referral backwards in time are also (...) untenable. Haggard, Cartledge, Dafydd, and Oakley report that a self-initiated act can, under hypnotic suggestion, appear to the subject to be “involuntary.” The act under hypnosis is better viewed as one initiated unconsciously, not as an act of conscious will. (shrink)

Alfred Mele develops a conceptual analysis of some of the concepts that inform the recent experimental studies of intentional action. Based on a distinction between unconscious urge and conscious decision, he suggests that the neural activity described by Libet’s experiments may represent an urge to move rather than a decision to do so, and that the decision to move might be made only when the subject becomes conscious of the urge. If this is the case, then Libet’s experiments do not (...) threaten freewill. (shrink)

Evidence is summarised for and against the hypothesis that potentiation or facilitation of neural responses during a train of threshold-level stimuli occurred in the experiments reported by Libet et al. . It is concluded that such potentiation probably did occur. Since the main arguments for the existence of subjective backwards referral take it as given that such potentiation did not occur, it is further concluded that the main arguments for the existence of subjective backwards referral fail.

Libet demonstrated that a substantial duration (>0.5-1.0 s) of direct electrical stimulation of the surface of a sensory cortex at a threshold or liminal current is required before a subject can experience a percept. Libet and his co-workers originally proposed that the result could be due either to spatial and temporal facilitation of the underlying neurons or additionally to a prolonged central processing time. However, over the next four decades, Libet chose to attribute the prolonged latency for evoking conscious experience (...) to a prolonged central processing time. In my view, Libet has not provided any convincing evidence, either on the basis of his own past work or in his critique of my paper, for his hypothesis of a central processing time exceeding 0.5s before conscious experience emerges following direct electrical threshold stimulation of the cortical surface. I stand by my original results and conclusion that such prolonged latencies are largely the consequence of a dynamically increasing cortical facilitatory process that begins hundreds of milliseconds before there is a sustained neuronal activation. In some cases, the facilitatory process must overcome an initial stimulus-induced inhibition before neuronal firing commences. (shrink)

Sensitivity to interpersonal timing was assessed in mother–infant interaction. In Study 1, 3-month-old infants interacted with their mothers over television and the mothers’ audio-visual presentation was either live or temporally delayed by 1 second. Infants gazed longer when the mother was presented live compared to delayed by 1 second, indicating that they detected the temporal delay. In Study 2, mothers interacted with their 3-month-old infants over television and the infants’ audio-visual presentation was either live or temporally delayed by 1 second. (...) Mothers’ behavior was not altered by a 1-second delay in their infants’ behavior compared to a live presentation. In Study 3 and 4, the results were replicated with 6-month-old infants. Whereas infants detected the temporal delay in maternal responses, mothers likely adjusted to the delay in infant behavior. The discussion focuses on the role of interpersonal timing for detecting social contingency in dyadic and triadic communication. (shrink)

Benjamin Libet and also Libet and collaborators claim to advance a single hypothesis, with important consequences, about the time of a conscious experience in relation to the time when there occurs a certain physical condition in the brain. This condition is spoken of as " _neural_ " _adequacy_ for the experience, or, as we can as well say, _neural adequacy_. 5 This finding has been taken to throw doubt on theories that take neural and mental events to be in necessary (...) or lawlike connection, and also certain identity theories of mind and brain, as well as determinist theories. (shrink)

This is a draft of a paper for a book Philosophy of Action: 5 Questions edited by Jesus Aguilar and Andrei Buckareff and to be published by Automatic Press / VIP. The book contains accounts by various philosophers, including leading theorists, of their engagement with problems of action and agency, and in particular determinism and freedom. The contributors also offer thoughts as to what attracted them to the subject, what their conclusions have been, what the benefit of the subject can (...) be to other subjects, what has been neglected in it, where work and inquiry should now be concentrated, and the prospects for progress. (shrink)

Abstract : Libet’s famous experiments, showing that apparently we become aware of our intention to act only after we have unconsciously formed it, have widely been taken to show that there is no such thing as free will. If we are not conscious of the formation of our intentions, many people think, we do not exercise the right kind of control over them. I argue that the claim this view presupposes, that only consciously initiated actions could be free, places a (...) condition upon freedom of action which it is in principle impossible to fulfil, for reasons that are conceptual and not merely contingent. Exercising this kind of control would require that we control our control system, which would simply cause the same problem to arise at a higher-level or initiate an infinite regress of controllings. If the unconscious initiation of actions, as well as the takings of decisions, is incompatible with control over them, then free will is impossible on conceptual grounds. Thus, Libet’s experiments do not constitute a separate, empirical, challenge to our freedom. (shrink)

Over a long career, Libet has conducted experiments that have shown, in clear and concrete ways, how the brain produces conscious awareness.

Leading scholars continue the debate over whether consciousness causes behavior or plays no functional role in it, discussing the question in terms of neuroscience, philosophy, law, and public policy.

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)

This research extends and confirms recent brainwave findings that distinguished an individual’s sense-of-self along an Object-referral/Self-referral Continuum of self-awareness. Subjects were interviewed and were given tests measuring inner/outer orientation, moral reasoning, anxiety, and personality. Scores on the psychological tests were factor analyzed. The first unrotated PCA component of the test scores yielded a “Consciousness Factor,” analogous to the intelligence “g” factor, which accounted for over half of the variance among groups. Analysis of unstructured interviews of these subjects revealed fundamentally different (...) descriptions of self-awareness. Individuals who described themselves in terms of concrete cognitive and behavioral processes exhibited lower Consciousness Factor scores, lower frontal EEG coherence, lower alpha and higher gamma power during tasks, and less efficient cortical preparatory responses . In contrast, individuals who described themselves in terms of an abstract, independent sense-of-self underlying thought, feeling and action exhibited higher Consciousness Factor scores, higher frontal coherence, higher alpha and lower gamma power during tasks, and more efficient cortical responses. These data suggest that definable states of brain activity and subjective experiences exist, in addition to waking, sleeping and dreaming, that may be operationally defined by psychological and physiological measures along a continuum of Object-referral/Self-referral Continuum of self-awareness. (shrink)