Contrary to assumptions that changes in brain networks are possible only during crucial periods of development, research in the past decade has supported the idea of a permanently plastic brain. Novel experience, altered afferent input due to environmental changes and learning new skills are now recognized as modulators of brain function and underlying neuroanatomic circuitry. Given findings in experiments with animals and the recent discovery of increases in gray and white matter in the adult human brain as a result (...) of learning, the old concept of cognitive reserve, that is the ability to reinforce brain volume in crucial areas and thus provide a greater threshold for age-dependent deficits, has been reinforced. The challenge we face is to unravel the exact nature of the dynamic structural alterations and, ultimately, to be able to use this knowledge for disease management. Understanding normative changes in brain structure that occur as a result of environmental changes and demands is pivotal to understanding the characteristic ability of the brain to adapt. (shrink)

Single-sided deafness (SSD) or profound unilateral hearing loss obligates the only serviceable ear to capture all acoustic information. This loss of binaural function taxes cognitive resources for accurate listening performance, especially under adverse environments or challenging tasks. We hypothesized that adults with SSD would manifest both functional and structural brain plasticity compared to controls with normal binaural hearing. We evaluated functional alterations using magnetoencephalographic imaging (MEGI) of brain activation during performance of a moderately difficult auditory syllable sequence reproduction task (...) and assessed structural integrity using diffusion tensor magnetic resonance imaging (DTI). MEGI showed the SSD cohort to have increased induced oscillations in the theta band over the left superior temporal cortex and decreased induced gamma band oscillations over the frontal and parietal cortices between 175-475 ms following stimulus onset. DTI showed the SSD cohort to have extensive fractional anisotropy reduction in both auditory and non-auditory tracts and regions. Overlaying functional and structural changes revealed by the two imaging techniques demonstrated close registration of cortical areas and white matter tracts that expressed brain plasticity. Hence, complete loss of input from one ear in adulthood triggers both functional and structural alterations to dorsal temporal and frontal-parietal areas. (shrink)

The anterior cingulate cortex (ACC) is a complex and continually evolving brain region that remains a primary focus of research due to its multifaceted functions. Various studies and analyses have significantly advanced our understanding of how the ACC participates in a wide spectrum of memory and cognitive processes. However, despite its strong connections to brain areas associated with hippocampal and olfactory neurogenesis, the functions of the ACC in regulating postnatal and adult neurogenesis in these regions are still insufficiently explored. (...) Investigating the intricate involvement of the ACC in neurogenesis could enhance our comprehension of essential aspects of brain plasticity. This involvement stems from its complex circuitry with other relevant brain regions, thereby exerting both direct and indirect impacts on the neurogenesis process. This review sheds light on the promising significance of the ACC in orchestrating postnatal and adult neurogenesis in conditions related to memory, cognitive behavior, and associated disorders. (shrink)

Long-term potentiation is one of the most extensively studied forms of neuroplasticity and is considered the strongest candidate mechanism for memory and learning. The use of event-related potentials and sensory stimulation paradigms has allowed for the translation from animal studies to non-invasive studies of LTP-like synaptic plasticity in humans. Accumulating evidence suggests that synaptic plasticity as measured by stimulus-specific response modulation is reduced in neuropsychiatric disorders such as major depressive disorder, bipolar disorders and schizophrenia, suggesting that impaired synaptic (...) plasticity plays a part in the underlying pathophysiology of these disorders. This is in line with the neuroplasticity hypothesis of depression, which postulate that deficits in neuroplasticity might be a common pathway underlying depressive disorders. The current study aims to replicate and confirm earlier reports that visual stimulus-specific response modulation is a viable probe into LTP-like synaptic plasticity in a large sample of healthy adults. Further, this study explores whether impairments in LTP-like synaptic plasticity is associated with self-reported subclinical depressive symptoms and stress in a healthy population. Consistent with prior research, the current study replicated and confirmed reports demonstrating significant modulation of visual evoked potentials following visual high-frequency stimulation. Current results further indicate that reduced LTP-like synaptic plasticity is associated with higher levels of self-reported symptoms of depression and perceived stress. This indicate that LTP-like plasticity is sensitive to sub-clinical levels of psychological distress, and might represent a vulnerability marker for the development of depressive symptoms. (shrink)

In the developing and adult cortex, just as in the adult hippocampus, LTP is unable to account for a variety of types of functional plasticity.

Neural transplantation as a recovery strategy for neuro-degenerative diseases in humans has used mainly grafting following acute denervation strategies in young adult hosts. Our work in aged mice and rats demonstrates an age-related increase in susceptibility to oxidative damage from neurotoxins, a remarkably poor recovery of C57BL/6 mice from MPTP insult with transplantation and growth factors, even at 12 months of age, and diminished plasticity of host neurons. We believe that extrapolation of data from young adult animal (...) models to aged humans without thorough investigation of transplantation and host response in aged recipients is scientifically and ethically inappropriate. (shrink)

Epigenetic control of gene expression by chromatin remodeling is critical for adult stem cell function. A decline in stem cell function is observed during aging, which is accompanied by changes in the chromatin structure that are currently unexplained. Here, we hypothesize that these epigenetic changes originate from the limited cellular capability to inherit epigenetic information. We suggest that spontaneous loss of histone modification, due to fluctuations over short time scales, gives rise to long‐term changes in DNA methylation and, accordingly, (...) in gene expression. These changes are assumed to impair stem cell function and, thus, to contribute to aging. We discuss cell replication as a major source of fluctuations in histone modification patterns. Gene silencing by our proposed mechanism can be interpreted as a manifestation of the conflict between the stem cell plasticity required for tissue regeneration and the permanent silencing of potentially deleterious genomic sequences. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Parenting Adults with ASD: Lessons for Researchers and CliniciansCassandra R. Newsom, Amy S. Weitlauf, Cora M. Taylor, and Zachary E. WarrenRecent reviews of treatments for individuals with autism spectrum disorders (ASD) reveal how little we still know about how to help adolescents with ASD and their families successfully transition into adulthood (Shattuck et al., 2012b; Taylor et al., 2012a). Shattuck and colleagues found that services in the United States (...) for adults with ASD were marked by high unemployment rates, a reliance on families to provide care across the lifespan, high turnover rates in front-line service providers, insufficient transition planning for high school students, and generally insufficient services to meet current needs. In a recent Agency for Healthcare Research and Quality (AHRQ) Comparative Effectiveness Review, the authors similarly found that there is very little evidence available to pinpoint specific intervention approaches for adolescents and young adults with ASD due to a lack of good quality studies. This was especially true for evidence-based approaches to support the transition of youth with ASD to adulthood (Taylor et al., 2012a).For the last decade, with dramatic increases in both ASD awareness and estimates of ASD prevalence, our field has understandably focused intensely on improving early detection and treatment of ASD. Our diagnostic tools and understanding of ASD presentation in very young children has improved tremendously. Different from many of the young adults in these stories, who were often diagnosed in their early teens, we now aim to identify children well before their third birthdays. Research has consistently shown that early and intense ASD-specific intervention can dramatically enhance outcomes for children with ASD. As such, there has been heavy investment in attempting to take full advantage of this early window of neuro-plasticity. However, as these stories illustrate, these children grow up. Their needs change, and our systems are often poorly equipped to help them live fulfilling lives, capitalize on their talents, and obtain independence and equal access, while still providing a safe, supportive environment. Without readily accessible and understandable coordinated systems of care, parents are forced to adopt the multiple roles of case manager, teacher, therapist, community educator, advocate, job coach, housing specialist, financial planner, and often, lifelong caregiver. These stories eloquently illustrate those struggles and successes.Grief and Joy: Opposite Sides of the Same Parenting CoinThe idea of grieving a diagnosis is controversial. Many of the writers seemed to feel conflicted about their grief responses and the validity of their feelings. Research shows that many families view the diagnostic process as extremely stressful (Siklos & [End Page 199] Kerns, 2005; Heiman, 2002). Feelings of sadness, anxiety, and depression are common at the point of diagnosis and may reemerge as milestones pass unmet. Families must modify the futures they imagined for their children and begin to envision new goals and dreams. Anonymous Three described this process when she wrote:Most children grow up, go to school, get jobs, move out of their parents’ home, etc. My husband and I have had to seriously consider how much of these are even possible for a young man with autism, even one who has a good number of functional life skills.Tasks of adolescence and adulthood such as starting high school, driving a car, and moving out of the house may be delayed and hard won if met. Raising a child with ASD appears to have particular challenges. Throughout this process, families begin to redefine what “success” means. Rather than ascribing to societal standards, they find joy in personal milestones. McDonald described the triumph of teaching his nephew to shake women’s hands instead of touching their hair, an important safety goal that took three months to accomplish. Each family thereby creates its own path.People outside of the family often do not understand the complicated interplay of love and obligation as well as the frustration and fulfillment that families experience. Just like any family, the parents of children with ASD describe many joys in addition to their struggles. They see their children’s strengths in a world that too often focuses on their weaknesses. Gifted with the everyday experience of their child’s development, they see past the necessity of a... (shrink)

Del Giudice's model belongs among those that highlight the role of adaptive developmental plasticity in human reproductive strategies; but at least three other forms of evolutionary adaptation also influence reproductive behavior. Similar to earlier models, the existing evidence suggests that Del Giudice's hypothesized effects are rather weak. In particular, adult attachment styles are hardly predictive of outcomes visible to natural selection.

An emerging concept is that quiescent mature skeletal cells provide an important cellular source for bone regeneration. It has long been considered that a small number of resident skeletal stem cells are solely responsible for the remarkable regenerative capacity of adult bones. However, recent in vivo lineage‐tracing studies suggest that all stages of skeletal lineage cells, including dormant pre‐adipocyte‐like stromal cells in the marrow, osteoblast precursor cells on the bone surface and other stem and progenitor cells, are concomitantly recruited (...) to the injury site and collectively participate in regeneration of the damaged skeletal structure. Lineage plasticity appears to play an important role in this process, by which mature skeletal cells can transform their identities into skeletal stem cell‐like cells in response to injury. These highly malleable, long‐living mature skeletal cells, readily available throughout postnatal life, might represent an ideal cellular resource that can be exploited for regenerative medicine. (shrink)

Neuroplasticity is a core feature of the brain throughout the entire life of the individual. And when injury to the adult brain destroys part of the circuitry mediating behaviour and/or conscious experience, neuroplasticity is required to bring about the highest possible degree of post-traumatic functional recovery. But is the brain able to recreate the lost circuitry? Scrutiny of the impressive plasticity seen during development and in the adult brain reveals many similarities -- but also some crucial differences. (...) And studies of the mechanisms of functional recovery demonstrate that even an apparently 'full recovery' of the surface phenomena of behaviour and/or conscious representations is accomplished without a recreation of the lost circuitry. Instead, the post-traumatic process utilizes mechanisms, which have evolved to mediate problem solving in the intact brain. The newly developed REF model suggests how such dynamic reorganizations occur in the intact and injured brain. (shrink)

Music impacting on speech processing is vividly evidenced in most reports involving professional musicians, while the question of whether the facilitative effects of music are limited to experts or may extend to amateurs remains to be resolved. Previous research has suggested that analogous to language experience, musicianship also modulates lexical tone perception but the influence of amateur musical experience in adulthood is poorly understood. Furthermore, little is known about how acoustic information and phonological information of lexical tones are processed by (...) amateur musicians. This study aimed to provide neural evidence of cortical plasticity by examining categorical perception of lexical tones in Chinese adults with amateur musical experience relative to the non-musician counterparts. Fifteen adult Chinese amateur musicians and an equal number of non-musicians participated in an event-related potential (ERP) experiment. Their mismatch negativities (MMNs) to lexical tones from Mandarin Tone 2–Tone 4 continuum and non-speech tone analogs were measured. It was hypothesized that amateur musicians would exhibit different MMNs to their non-musician counterparts in processing two aspects of information in lexical tones. Results showed that the MMN mean amplitude evoked by within-category deviants was significantly larger for amateur musicians than non-musicians regardless of speech or non-speech condition. This implies the strengthened processing of acoustic information by adult amateur musicians without the need of focused attention, as the detection of subtle acoustic nuances of pitch was measurably improved. In addition, the MMN peak latency elicited by across-category deviants was significantly shorter than that by within-category deviants for both groups, indicative of the earlier processing of phonological information than acoustic information of lexical tones at the pre-attentive stage. The results mentioned above suggest that cortical plasticity can still be induced in adulthood, hence non-musicians should be defined more strictly than before. Besides, the current study enlarges the population demonstrating the beneficial effects of musical experience on perceptual and cognitive functions, namely, the effects of enhanced speech processing from music are not confined to a small group of experts but extend to a large population of amateurs. (shrink)

Developmental biology is expanding into several new areas. One new area of study concerns the production of adult-onset phenotypes by exposure of the fetus or neonate to environmental agents. These agents include maternal nutrients, developmental modulators (endocrine disruptors), and maternal care. In all three cases, a major mechanism for the generation of the altered phenotype is chromatin modification. Nutrient conditions, developmental modulators, and even maternal care appear to alter DNA methylation and other associated changes in chromatin that regulate gene (...) expression. This brings a new, under-appreciated, dimension of gene regulation into developmental biology, and it also demonstrates the poverty of the nature versus nurture framework for discussing phenotype production. Moreover, while such epigenetic mechanisms undermine genetic determinism, they add a layer of probabilistic biological causality for the maintenance of social inequalities. (shrink)

Previously published studies have reported that 150 min of short-term monocular deprivation temporarily changes perceptual eye dominance. However, the possible mechanisms underlying monocular deprivation-induced perceptual eye dominance plasticity remain unclear. Using a binocular phase and contrast co-measurement task and a multi-pathway contrast-gain control model, we studied the effect of 150 min of monocular pattern deprivation in normal adult subjects. The perceived phase and contrast varied significantly with the interocular contrast ratio, and after MPD, the patched eye became dominant. (...) Most importantly, we focused on the potential mechanisms of the deprivation effect. The data of an averaged subject was best fitted by a model, which assumed a monocular signal enhancement of the PE after the MPD. The present findings might have important implications for investigations of binocular vision in both normal and amblyopic populations. (shrink)

This article reviews how behavioral methods, event-related potentials, and functional magnetic resonance imaging are used to understand the acquisition of perceptual expertise in both adult and developmental populations. The purpose of this study is to provide an overview of the research focused on understanding the role and nature of experience in both the acquisition of perceptual expertise and the development of expert face processing. Behavioral tasks designed to assess perceptual expertise in adults include: perceptual discrimination and matching tasks and (...) the categorization and recognition memory tasks. Training studies are used to mimic the natural acquisition of face and non-face perceptual expertise. Using these various methods and techniques, studies of perceptual expertise prove useful to the understanding of specialization of perceptual skills and categorization abilities and expands our understanding of the function and plasticity of the visual system. (shrink)

Transcranial magnetic stimulation studies have demonstrated increased cortical facilitation and reduced inhibition following aerobic exercise, even when examining motor regions separate to the exercised muscle group. These changes in brain physiology following exercise may create favorable conditions for adaptive plasticity and motor learning. One candidate mechanism behind these benefits is the increase in brain-derived neurotropic factor observed following exercise, which can be quantified from a venous blood draw. The aim of this study was to investigate changes in motor cortex (...) excitability and inhibition of the upper limb, and circulating BDNF, following high-intensity interval training on a stationary bicycle. Nineteen sedentary adults participated in a randomized crossover design study involving a single bout of high-intensity interval cycling for 20 min or seated rest. Venous blood samples were collected, and transcranial magnetic stimulation was used to stimulate the extensor carpi radialis, where motor evoked potentials were recorded pre- and post-condition. Following exercise, there was a significant increase in corticospinal excitability measured at 120% of resting motor threshold and a reduction in short-interval cortical inhibition. There was a non-significant 23.6% increase in BDNF levels. Collectively, these results reflect a net reduction in gamma aminobutyric acid ergic synaptic transmission and increased glutamatergic facilitation, resulting in increased corticospinal excitability. This study supports the notion that acute high-intensity exercise provides a potent stimulus for inducing cortical neuroplasticity, which may support enhanced motor learning. (shrink)

ObjectivesWorking memory is essential for daily life skills like reading comprehension, reasoning, and problem-solving. Healthy aging of the brain goes along with working memory decline that can affect older people’s independence in everyday life. Interventions in the form of cognitive training are a promising tool for delaying age-related working memory decline, yet the underlying structural plasticity of white matter is hardly studied.MethodsWe conducted a longitudinal diffusion tensor imaging study to investigate the effects of an intensive four-week adaptive working memory (...) training on white matter integrity quantified by global and tract-wise mean diffusivity. We compared diffusivity measures of fiber tracts that are associated with working memory of 32 young and 20 older participants that were randomly assigned to a working memory training group or an active control group.ResultsThe behavioral analysis showed an increase in working memory performance after the four-week adaptive working memory training. The neuroanatomical analysis revealed a decrease in mean diffusivity in the working memory training group after the training intervention in the right inferior longitudinal fasciculus for the older adults. There was also a decrease in mean diffusivity in the working memory training group in the right superior longitudinal fasciculus for the older and young participants after the intervention.ConclusionThis study shows that older people can benefit from working memory training by improving their working memory performance that is also reflected in terms of improved white matter integrity in the superior longitudinal fasciculus and the inferior longitudinal fasciculus, where the first is an essential component of the frontoparietal network known to be essential in working memory. (shrink)

Pigment cells in zebrafish − melanophores, iridophores, and xanthophores − originate from neural crest‐derived stem cells associated with the dorsal root ganglia of the peripheral nervous system. Clonal analysis indicates that these progenitors remain multipotent and plastic beyond embryogenesis well into metamorphosis, when the adult color pattern develops. Pigment cells share a lineage with neuronal cells of the peripheral nervous system; progenitors propagate along the spinal nerves. The proliferation of pigment cells is regulated by competitive interactions among cells of (...) the same type. An even spacing involves collective migration and contact inhibition of locomotion of the three cell types distributed in superimposed monolayers in the skin. This mode of coloring the skin is probably common to fish, whereas different patterns emerge by species specific cell interactions among the different pigment cell types. These interactions are mediated by channels involved in direct cell contact between the pigment cells, as well as unknown cues provided by the tissue environment. (shrink)

Maintaining and coordinating multiple task-sets is difficult and leads to costs, however task-switching training can reduce these deficits. A recent study in young adults demonstrated that this training effect occurs at an amodal processing level. Old age is associated with reduced cognitive plasticity and further increases the performance costs when mixing multiple tasks. Thus, cognitive aging might be a limiting factor for inducing cross-modal training effects in a task-switching environment. We trained participants, aged 62–83 years, with an auditory task-switching (...) paradigm over four sessions, to investigate whether training-related reductions in task-switching costs would also manifest in an untrained visual modality version of the task. Two control groups trained with single tasks or not trained allowed us to identify improvements specific to task-switching training. To make statistical evaluations of any age differences in training and cross-modal transfer, the data from the Kattner cohort were incorporated into the present analysis. Despite the tendency for older adults to respond more cautiously, task-switching training specifically led to a mixing cost reduction in both trained and untrained modalities, the magnitude of which was statistically similar regardless of age. In line with a growing body of research, we failed to observe any far transfer effects in measures of inhibition, working memory or fluid intelligence. Overall, we conclude that any apparent cognitive limitations associated with aging do not prevent cognitive control processes which support set-shifting from improving at an amodal level. (shrink)

Substantial evidence indicates that cognitive training can be efficacious for older adults, but findings regarding training-related brain plasticity have been mixed and vary depending on the imaging modality. Recent years have seen a growth in recognition of the importance of large-scale brain networks on cognition. In particular, task-induced deactivation within the default mode network is thought to facilitate externally directed cognition, while aging-related decrements in this neural process are related to reduced cognitive performance. It is not yet clear whether (...) task-induced deactivation within the DMN can be enhanced by cognitive training in the elderly. We previously reported durable cognitive improvements in a sample of healthy older adults who completed 6 weeks of process-based object-location memory training compared to an active control training group. The primary aim of the current study is to evaluate whether these cognitive gains are accompanied by training-related changes in task-related DMN deactivation. Given the evidence for heterogeneity of the DMN, we examine task-related activation/deactivation within two separate DMN branches, a ventral branch related to episodic memory and a dorsal branch more closely resembling the canonical DMN. Participants underwent functional magnetic resonance imaging while performing an untrained object-location memory task at four time points before, during, and after the training period. Task-induced activation values were extracted for the ventral and dorsal DMN branches at each time point. Relative to visual fixation baseline: the dorsal DMN was deactivated during the scanner task, while the ventral DMN was activated; the object-location memory training group exhibited an increase in dorsal DMN deactivation relative to the active control group over the course of training and follow-up; changes in dorsal DMN deactivation did not correlate with task improvement. These results indicate a training-related enhancement of task-induced deactivation of the dorsal DMN, although the specificity of this improvement to the cognitive task performed in the scanner is not clear. (shrink)

Neurosteroid 17 beta-estradiol (E2) is a steroid synthesized de novo in the nervous system that might influence neuronal activity and behavior. Nevertheless, the impact of E2 on the functioning of those neural systems in which it is slightly synthesized is less questioned. The vestibulo-ocular reflex (VOR) adaptation, may provide an ideal arena for investigating this issue. Indeed, E2 modulates cerebellar parallel fiber-Purkinje cell synaptic plasticity that underlies encoding of VOR adaptation. Moreover, aromatase expression in the cerebellum of adult (...) rodents is maintained at very low levels and localized to Purkinje cells. The significance of age-related maintenance of low levels of aromatase expression in the cerebellum on behavior, however, has yet to be explored. Our aim in this study was to determine whether E2 synthesis exerts an effective and persistent modulation of VOR adaptation in adult male rats. To answer this question, we investigated the acute effect of blocking E2 synthesis on gain increases and decreases in VOR adaptation using an oral dose (2.5 mg/kg) of the aromatase inhibitor Letrozole in peri-pubertal and post-pubertal male rats. We found that Letrozole acutely impaired gain increases and decreases in VOR adaptation without altering basal ocular-motor performance and that these effects were similar in peri-pubertal and post-pubertal rats. Thus, in adult male rats neurosteroid E2 effectively modulates VOR adaptation in both of the periods studied. These findings imply that the adult cerebellum uses E2 synthesis for modulating motor memory formation and suggest that low and extremely localized E2 production may play a role in adaptive phenomena. (shrink)

The output from motor neuron pools is influenced by the integration of synaptic inputs originating from descending corticomotor and spinal reflex pathways. In this study, using paired non-invasive brain and peripheral nerve stimulation, we investigated how descending corticomotor pathways influence the physiologic recruitment order of the soleus Hoffmann reflex. Eleven neurologically unimpaired adults completed an assessment of transcranial magnetic stimulation -conditioning of the soleus H-reflex over a range of peripheral nerve stimulation intensities. Unconditioned H-reflex recruitment curves were obtained by delivering (...) PNS pulses to the posterior tibial nerve. Subsequently, TMS-conditioned H-reflex recruitment curves were obtained by pairing PNS with subthreshold TMS at short and long intervals. We evaluated unconditioned and TMS-conditioned H-reflex amplitudes along the ascending limb, peak, and descending limb of the H-reflex recruitment curve. Our results revealed that, for long-interval facilitation, TMS-conditioned H-reflex amplitudes were significantly larger than unconditioned H-reflex amplitudes along the ascending limb and peak of the H-reflex recruitment curve. Additionally, significantly lower PNS intensities were needed to elicit peak H-reflex amplitude for long-interval facilitation compared to unconditioned. These findings suggest that the influence of descending corticomotor pathways, particularly those mediating long-interval facilitation, contribute to changing the recruitment gain of the motor neuron pool, and can inform future methodological protocols for TMS-conditioning of H-reflexes. By characterizing and inducing short-term plasticity in circuitry mediating short- and long-interval TMS-conditioning of H-reflex amplitudes, future studies can investigate supraspinal and spinal circuit contributions to abnormal motor control, as well as develop novel therapeutic targets for neuromodulation. (shrink)

GraphicalExercise, neurotransmitters, growth factors, myokines, and potential effects on the brain.As human life expectancy increases, cognitive decline and memory impairment threaten independence and quality of life. Therefore, finding prevention and treatment strategies for memory impairment is an important health concern. Moreover, a better understanding of the mechanisms involved underlying memory preservation will enable the development of appropriate pharmaceuticals drugs for those who are activity limited. Exercise training as a non-pharmacological tool, has been known to increase the mean lifespan by maintaining (...) general body health and improving the cardiovascular and nervous systems function. Among different exercise training protocols, aerobic exercise has been reported to prevent the progression of memory decline, provided adequate exertion level, duration, and frequency. Mechanisms underlying exercise training effects on memory performance have not been understood yet. Convergent evidence suggest several direct and indirect mechanisms at molecular and supramolecular levels. The supramolecular level includes improvement in blood circulation, synaptic plasticity and neurogenesis which are under controls of complex molecular signaling of neurotransmitters, neurotrophic factors, exerkines, and epigenetics factors. Among these various factors, irisin/BDNF signaling seems to be one of the important mediators of crosstalk between contracted skeletal muscles and the brain during exercise training. This review provides an affordable and effective method to improve cognitive function in old ages, particularly those who are most vulnerable to neurodegenerative disorders. (shrink)

Although speech categories are defined by multiple acoustic dimensions, some are perceptually weighted more than others and there are residual effects of native-language weightings in non-native speech perception. Recent research on nonlinguistic sound category learning suggests that the distribution characteristics of experienced sounds influence perceptual cue weights: Increasing variability across a dimension leads listeners to rely upon it less in subsequent category learning (Holt & Lotto, 2006). The present experiment investigated the implications of this among native Japanese learning English /r/-/l/ (...) categories. Training was accomplished using a videogame paradigm that emphasizes associations among sound categories, visual information, and players’ responses to videogame characters rather than overt categorization or explicit feedback. Subjects who played the game for 2.5 h across 5 days exhibited improvements in /r/-/l/ perception on par with 2–4 weeks of explicit categorization training in previous research and exhibited a shift toward more native-like perceptual cue weights. (shrink)

This target article presents an integrated evolutionary model of the development of attachment and human reproductive strategies. It is argued that sex differences in attachment emerge in middle childhood, have adaptive significance in both children and adults, and are part of sex-specific life history strategies. Early psychosocial stress and insecure attachment act as cues of environmental risk, and tend to switch development towards reproductive strategies favoring current reproduction and higher mating effort. However, due to sex differences in life history trade-offs (...) between mating and parenting, insecure males tend to adopt avoidant strategies, whereas insecure females tend to adopt anxious/ambivalent strategies, which maximize investment from kin and mates. Females are expected to shift to avoidant patterns when environmental risk is more severe. Avoidant and ambivalent attachment patterns also have different adaptive values for boys and girls, in the context of same-sex competition in the peer group: in particular, the competitive and aggressive traits related to avoidant attachment can be favored as a status-seeking strategy for males. Finally, adrenarche is proposed as the endocrine mechanism underlying the reorganization of attachment in middle childhood, and the implications for the relationship between attachment and sexual development are explored. Sex differences in the development of attachment can be fruitfully integrated within the broader framework of adaptive plasticity in life history strategies, thus contributing to a coherent evolutionary theory of human development. (shrink)

Many sensory processing regions of the central brain undergo critical periods of experience‐dependent plasticity. During this time ethologically relevant information shapes circuit structure and function. The mechanisms that control critical period timing and duration are poorly understood, and this is of special importance for those later periods of development, which often give rise to complex cognitive functions such as social behavior. Here, we review recent findings in Drosophila, an organism that has some unique experimental advantages, and introduce novel views (...) for manipulating plasticity in the post‐embryonic brain. Critical periods in larval and young adult flies resemble classic vertebrate models with distinct onset and termination, display clear connections with complex behaviors, and provide opportunities to control the time course of plasticity. These findings may extend our knowledge about mechanisms underlying extension and reopening of critical periods, a concept that has great relevance to many human neurodevelopmental disorders. (shrink)

This target article presents an integrated evolutionary model of the development of attachment and human reproductive strategies. It is argued that sex differences in attachment emerge in middle childhood, have adaptive significance in both children and adults, and are part of sex-specific life history strategies. Early psychosocial stress and insecure attachment act as cues of environmental risk, and tend to switch development towards reproductive strategies favoring current reproduction and higher mating effort. However, due to sex differences in life history trade-offs (...) between mating and parenting, insecure males tend to adopt avoidant strategies, whereas insecure females tend to adopt anxious/ambivalent strategies, which maximize investment from kin and mates. Females are expected to shift to avoidant patterns when environmental risk is more severe. Avoidant and ambivalent attachment patterns also have different adaptive values for boys and girls, in the context of same-sex competition in the peer group: in particular, the competitive and aggressive traits related to avoidant attachment can be favored as a status-seeking strategy for males. Finally, adrenarche is proposed as the endocrine mechanism underlying the reorganization of attachment in middle childhood, and the implications for the relationship between attachment and sexual development are explored. Sex differences in the development of attachment can be fruitfully integrated within the broader framework of adaptive plasticity in life history strategies, thus contributing to a coherent evolutionary theory of human development. (shrink)

Phenotypic Evolution explicitly recognizes organisms as complex genetic-epigenetic systems developing in response to changing internal and external environments. As a key to a better understanding of how phenotypes evolve, the authors have developed a framework that centers on the concept of the Developmental Reaction Norm. This encompasses their views: (1) that organisms are better considered as integrated units than as disconnected parts (allometry and phenotypic integration); (2) that an understanding of ontogeny is vital for evaluating evolution of adult forms (...) (ontogenetic trajectories, epigenetics, and constraints); and (3) that environmental heterogeneity is ubiquitous and must be acknowledged for its pervasive role in phenotypic expression. (shrink)

Almost everyone who has a limb amputated will experience a phantom limb--the vivid impression that the limb is not only still present, but in some cases, painful. There is now a wealth of empirical evidence demonstrating changes in cortical topography in primates following deafferentation or amputation, and this review will attempt to relate these in a systematic way to the clinical phenomenology of phantom limbs. With the advent of non-invasive imaging techniques such as MEG (magnetoencephalogram) and functional MRI, topographical reorganization (...) can also be demonstrated in humans, so that it is now possible to track perceptual changes and changes in cortical topography in individual patients. We suggest, therefore, that these patients provide a valuable opportunity not only for exploring neural plasticity in the adult human brain but also for understanding the relationship between the activity of sensory neurons and conscious experience. We conclude with a theory of phantom limbs, some striking demonstrations of phantoms induced in normal subjects, and some remarks about the relevance of these phenomena to the question of how the brain constructs a 'body image.'. (shrink)

Reading in the Brain (Les neurones de la lecture, 2007) examined the origins of human reading abilities in the light of contemporary cognitive neuroscience. It argued that reading acquisition, in all cultures, recycles preexisting cortical circuits dedicated to invariant visual recognition, and that the organization of these circuits imposes strong constraints on the invention and cultural evolution of writing systems. In this article, seven years later, I briefly review new experimental evidence, particularly from brain imaging studies of illiterate adults, which (...) indicates that reading acquisition invades culturally universal cortical circuits and competes with their prior function, including mirror-invariant visual recognition and face processing. In response to my critics, I emphasize how brain plasticity and brain constraints can be reconciled within the Bayesian perspective on learning. I also discuss the importance of a newly discovered gesture system in reading and writing. Finally, I argue that there is consistent evidence for deep cross-cultural universals in writing systems, as well as for the multiple subtypes of dyslexia that are expected given the broad set of areas recruited by the reading task. (shrink)

In vision research metacontrast masking is a widely used technique to reduce the visibility of a stimulus. Typically, studies attempt to reveal general principles that apply to a large majority of participants and tend to omit possible individual differences. The neural plasticity of the visual system, however, entails the potential capability for individual differences in the way observers perform perceptual tasks. We report a case of perceptual learning in a metacontrast masking task that leads to the enhancement of two (...) types of adult human observers despite identical learning conditions. In a priming task both types of observers exhibited the same priming effects, which were insensitive to learning. Findings suggest that visual processing of target stimuli in the metacontrast masking task is based on neural levels with sufficient plasticity to enable the development of two types of observers, which do not contribute to processing of target stimuli in the priming task. (shrink)

Fitting the Mind to the World explores the brain's remarkable capacity to adapt to its current visual environment. Leading vision researchers explore how visual experience alters the adult brain, fitting the mind to the world, and ensuring the efficient coding of sensory signals. They demonstrate how this plasticity affects every aspect of our visual experience, from the perception of movement and colour, to the perception of subtle, social and emotional information in human faces.

Evolutionary psychologists claim that the mind contains “hundreds or thousands” of “genetically specified” modules, which are evolutionary adaptations for their cognitive functions. We argue that, while the adult human mind/brain typically contains a degree of modularization, its “modules” are neither genetically specified nor evolutionary adaptations. Rather, they result from the brain’s developmental plasticity, which allows environmental task demands a large role in shaping the brain’s information-processing structures. The brain’s developmental plasticity is our fundamental psychological adaptation, and the (...) “modules” that result from it are adaptive responses to local conditions, not past evolutionary environments. If different individuals share common environ- ments, however, they may develop similar “modules,” and this process can mimic the development of genetically specified modules in the evolutionary psychologist’s sense. (shrink)

Many people believe that human beings begin to exist with the emergence of the 1-cell zygote at fertilization. I present a novel argument against this belief, one based on recently discovered facts about human embryo development. I first argue that a human zygote is developmentally plastic: A zygote that naturally develops into a singleton (i.e., develops into exactly one infant/adult without twinning) might have naturally developed into a numerically different singleton. From this, I derive the conclusion that a human (...) infant or adult is numerically distinct from the zygote she came from and so did not begin to exist at fertilization. This implies that a zygote does not have a “future like ours” and strongly suggests that it is not a human being. (shrink)

It is now well recognized that the United States is a consumer-driven society. Private consumption comprises a rising fraction of GDP, advertising is proliferating, and consumerism, as an ideology and set of values, is widespread. Not surprisingly, those developments are not confined to adults; they also characterize what some have called “the commercialization of childhood.” Children are more involved than ever in media, celebrity, shopping, brand names, and other consumer practices. At the core of this change is children's growing role (...) as independent consumers. In recent years, children's access to income has risen markedly, and they have gone from being purchasers of cheap plastic goods and a few select food items to being a major market for a diverse set of goods and services, including foodstuffs. Unofficial estimates suggest that children aged four to twelve spent a reported $6.1 billion in purchases from their own money in 1989, $23.4 billion in 1997, and $30 billion in 2002, for a total increase of four hundred percent. (shrink)

Innate emotional bases of ethics have been proposed by authors in evolutionary psychology, following Darwin and his sources in eighteenth-century moral philosophy. Philosophers often tend to view such theories as irrelevant to, or even as tending to undermine, the project of moral philosophy. But the importance of emotions to early moral learning gives them a role to play in determining the content of morality. I argue, first, that research on neural circuits indicates that the basic elements or components of emotions (...) need not be limited to what psychologists think of as basic emotions. But in that case, innate mechanisms of social transfer of emotion, such as infants’ tendency to facial imitation, gaze-following, and emotional contagion or empathy, provide a source of plasticity in developing the basic elements that lets emotions incorporate cultural influence from early on. This leaves room later for cognitive components of adult human emotions and hence for the further role of language in conveying cultural influence. We can thus see how moral judgment might depend on innate emotional capacities that are both modifiable by culture and capable of registering objective values. I use Rawls’s treatment of the development of moral sentiments to illustrate the kind of supportive role that emotions can play in a principle-based account – though my own account involves modifications I go on to indicate. (shrink)

In the UK, female genital mutilation is unlawful, not only when performed on minors, but also when performed on adult women. The aim of our paper is to examine several arguments which have been advanced in support of this ban and to assess whether they are sufficient to justify banning female genital mutilation for competent, consenting women. We proceed by comparing female genital mutilation, which is banned, with cosmetic surgery, towards which the law has taken a very permissive stance. (...) We then examine the main arguments for the prohibition of the former, assessing in each case both (a) whether the argument succeeds in justifying the ban and, if so, (b) whether a parallel argument would not also support a ban on the latter. We focus on the following arguments. Female genital mutilation should be unlawful because: (1) no woman could validly consent to it; (2) it is an oppressive and sexist practice; (3) it involves the intentional infliction of injury; (4) it causes offence. Our view is that arguments (3) and (4) are unsound and that, although arguments (1) and (2) may be sound, they support not only a ban on female genital mutilation, but also one on (some types of) costmetic surgery. Hence, we conclude that the present legal situation in the UK is ethically unsustainable in one of the following ways. Either the ban on female genital mutilation is unjustified because arguments (1) and (2) are not in fact successful; or the law's permissive attitude towards cosmetic surgery is unjustified because arguments (1) and (2) are in fact successful and apply equally to female genital mutilation and (certain forms of) cosmetic surgery. The people of the countries where female genital mutilation is practised resent references to ‘barbaric practices imposed on women by male‐dominated primitive societies’, especially when they look at the Western world and see women undergoing their own feminization rites intended to increase sexual desirability: medically dangerous forms of cosmetic plastic surgery, for instance …. (shrink)

The great powers of regeneration shown by freshwater planarians, capable of regenerating a complete organism from any tiny body fragment, have attracted the interest of scientists throughout history. In 1814, Dalyell concluded that planarians could “almost be called immortal under the edge of the knife”. Equally impressive is the developmental plasticity of these platyhelminthes, including continuous growth and fission (asexual reproduction) in well‐fed organisms, and shrinkage (degrowth) during prolonged starvation. The source of their morphological plasticity and regenerative capability (...) is a stable population of totipotent stem cells—“neoblasts”; this is the only cell type in the adult that has mitotic activity and differentiates into all cell types. This cellular feature is unique to planarians in the Bilateria clade. Over the last fifteen years, molecular studies have begun to reveal the role of developmental genes in regeneration, although it would be premature to propose a molecular model for planarian regeneration. Genomic and proteomic data are essential in answering some of the fundamental questions concerning this remarkable morphological plasticity. Such information should also pave the way to understanding the genetic pathways associated with metazoan somatic stem‐cell regulation and pattern formation. BioEssays 28: 546–559, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

Culture can be said to be about the business of 'self-replication'. From the moment of conception, it impresses its patterns and rhythms on the developing, infinitely plastic neuronal substrate of the fetal organism. It shapes this substrate to become preferentially sensitive to its patterns and thus to seek to replicate them as an adult. This process of neural shaping continues throughout life as the capacity of the brain to reorganize itself according to the uses to which it addresses itself (...) never ceases. The extraordinary capacity of culture to extract different abilities from the biological form is clearly manifest in the lexical, vocal, tool manufacture, and writing capabilities emerging in bonobos raised in a Pan/Homo culture. These findings render moot old questions regarding the innate limits of the ape brain. They raise instead far more productive questions about the form and function of the perpetual dance that is constantly taking place between plastic neuronal systems and their external culturally devised ways of being. (shrink)

As befits a French philosopher of the 1960s, Gilles Deleuze (1925-995), was famous for his antihumanism and his anti-essentialism. Humans are fully part of nature with no supernatural supplement; and essences are not the way to individuate things. That doesn’t seem to leave much room for a Deleuzean human nature, but that’s what I want to try to explore. I’ll take my clue from what he says in A Thousand Plateaus about nomads, who “reterritorialize on their power of deterritorialization.” In (...) other words, they are most at home when on the move. But this isn’t just spatial movement; we can also say that the habit of nomads is to break habits. I’ll make sense of this claim by referring to Bruce Wexler’s Brain and Culture (MIT, 2006), in particular, his claim that humans evolved for a lengthy childhood period of socially mediated neuroplasticity. Human nature on this view is such that we are individuated by our singular patterns of social – somatic interaction. And this in turn is “nomadic” in Deleuze’s sense: our nature is to be so open to our nurture that it becomes second nature. That is, we’re at home wherever home is. There’s an anti-essentialist nuance here, however. It’s children who are most “nomadic,” most plastic. Most adults drift away from nomadism and become sedentary: they want more of the same. But even here we must nuance things: what if “more of the same” means “more change”? In other words, are there adult “nomads”? I think there are. But we’ll need to discuss Deleuze’s ontology first in order to make sense of these claims. Deleuze is an interactive process philosopher: we aren't substances but processes and those processes are not individuated by properties but as singular patterns of social and somatic interaction. The embodied and the embedded aspects of our being intersect – we are bodies whose capacities form in social interaction. And it's in this intersection of the social and the somatic that subjectivity and selfhood emerge – and are sometimes attenuated and even bypassed.. (shrink)

In this chapter, data concerning the development of principal aspects of vision is reviewed. First, the development of colour vision and luminance perception is discussed. Relevant data accumulated so far indicates that perception of colour and luminance is present by 6-9 months of age. The presence of typical color illusions at this age suggests that the phenomenal character of color experience is comparable to that of adults well before the first birthday. Thus it seems plausible that color perception develops on (...) the grounds of genetically preprogrammed maturation, in which perceptual learning and plasticity play a limited role. This claim also seems to be supported by case studies of newly sighted patients. On the other hand, perceptual integration of edges and forms in the visual environment as well as the development of binocular vision, and the perception of ambiguous figures seem to depend crucially on early perceptual learning. Both developmental and clinical data indicate a more significant involvement of perceptual learning in such mid-level and higher level perceptual phenomena. (shrink)

BackgroundIn gender-affirming medical care (GAMC), ethical challenges in decision-making are ubiquitous. These challenges are becoming more pressing due to exponentially increasing referrals, politico-legal contestation, and divergent normative views regarding decisional roles and models. Little is known, however, about what ethical challenges related to decision-making healthcare professionals (HCPs) themselves face in their daily work in GAMC and how these relate to, for example, the subjective nature of Gender Incongruence (GI), the multidisciplinary character of GAMC and the role HCPs play in assessing (...) GI and eligibility for interventions. Given the relevance and urgency of these questions, we conducted a qualitative study among HCPs providing GAMC to transgender adults in the Netherlands.MethodsIn this qualitative research, we conducted 11 semi-structured interviews between May 2020 and February 2021 with HCPs (six mental health professionals, two HCPs in endocrinology, two in plastic surgery, and one in nursing) working in two distinct GAMC settings. We purposively sampled for professional background and years of experience in GAMC. We analyzed our interview data using thematic analysis. As some respondents were more inclined to speak about what should or ought to be done to arrive at good or right decision-making, we identified both ethical challenges and norms. Furthermore, in our analysis, we differentiated between respondents’ explicit and implicit ethical challenges and norms and ascertained the specific context in which these challenges emerged.ResultsRespondents’ ethical challenges and norms centered on (1) dividing and defining decisional roles and bounds, (2) negotiating decision-making in a (multidisciplinary) team, and (3) navigating various decision-making temporalities. These themes arose in the context of uncertainties regarding (1) GAMC’s guidelines, evidence, and outcomes, as well as (2) the boundaries and assessment of GI.ConclusionsThis interview study provides detailed empirical insight into both the explicit and implicit ethical challenges that HCPs experience and their ethical norms regarding decision-making. It also describes how uncertainties and (implicit) normativities concerning GAMC and GI pre-structure the moral environment in which these challenges and norms manifest. We provide normative reflections and recommendations on handling these ethical challenges in a way that is sensitive to the context in which they arise. (shrink)

During brain development, neural precursor cells (NPCs) in different brain regions produce different types of neurons, and each of these regions plays a different role in the adult brain. Therefore, precise regionalization is essential in the early stages of brain development, and irregular regionalization has been proposed as the cause of neurodevelopmental disorders. The mechanisms underlying brain regionalization have been well studied in terms of morphogen‐induced expression of critical transcription factors for regionalization. NPC potential in different brain regions is (...) defined by chromatin structures that regulate the plasticity of gene expression. Herein, we present recent findings on the importance of chromatin structure in brain regionalization, particularly with respect to its regulation by Polycomb‐group proteins and chromatin accessibility. (shrink)