A key question in understanding visual awareness is whether any single cortical area is indispensable. In a transcranial magnetic stimulation experiment, we show that observers' awareness of activity in extrastriate area VS depends on the amount of activity in striate cortex (Vl). From the timing and pattern of effects, we infer that back-projections from extrastriate cortex influence information content in Vl, but it is Vl that determines whether that information reaches awareness.

A broad range of evidence regarding the functional organization of the vertebrate brain – spanning from comparative neurology to experimental psychology and neurophysiology to clinical data – is reviewed for its bearing on conceptions of the neural organization of consciousness. A novel principle relating target selection, action selection, and motivation to one another, as a means to optimize integration for action in real time, is introduced. With its help, the principal macrosystems of the vertebrate brain can be seen to form (...) a centralized functional design in which an upper brain stem system organized for conscious function performs a penultimate step in action control. This upper brain stem system retained a key role throughout the evolutionary process by which an expanding forebrain – culminating in the cerebral cortex of mammals – came to serve as a medium for the elaboration of conscious contents. This highly conserved upper brainstem system, which extends from the roof of the midbrain to the basal diencephalon, integrates the massively parallel and distributed information capacity of the cerebral hemispheres into the limited-capacity, sequential mode of operation required for coherent behavior. It maintains special connective relations with cortical territories implicated in attentional and conscious functions, but is not rendered nonfunctional in the absence of cortical input. This helps explain the purposive, goal-directed behavior exhibited by mammals after experimental decortication, as well as the evidence that children born without a cortex are conscious. Taken together these circumstances suggest that brainstem mechanisms are integral to the constitution of the conscious state, and that an adequate account of neural mechanisms of conscious function cannot be confined to the thalamocortical complex alone. (Published Online May 1 2007) Key Words: action selection; anencephaly; central decision making; consciousness; control architectures; hydranencephaly; macrosystems; motivation; target selection; zona incerta. (shrink)

Background Speech understanding may rely not only on auditory, but also on visual information. Non-invasive functional neuroimaging techniques can expose the neural processes underlying the integration of multisensory processes required for speech understanding in humans. Nevertheless, noise (from fMRI) limits the usefulness in auditory experiments, and electromagnetic artefacts caused by electronic implants worn by subjects can severely distort the scans (EEG, fMRI). Therefore, we assessed audio-visual activation of temporal cortex with a silent, optical neuroimaging technique: functional near-infrared spectroscopy (fNIRS). (...) Methods We studied temporal cortical activation as represented by concentration changes of oxy- and deoxy-hemoglobin in four, easy-to-apply fNIRS optical channels of 33 normal-hearing adult subjects and 5 post-lingually deaf cochlear implant (CI) users in response to supra-threshold unisensory auditory and visual, as well as to congruent auditory-visual speech stimuli. Results Activation effects were not visible from single fNIRS channels. However, by discounting physiological noise through reference channel subtraction, auditory, visual and audiovisual speech stimuli evoked concentration changes for all sensory modalities in both cohorts (p<0.001). Auditory stimulation evoked larger concentration changes than visual stimuli (p<0.001). A saturation effect was observed for the audiovisual condition. Conclusions Physiological, systemic noise can be removed from fNIRS signals by reference channel subtraction. The observed multisensory enhancement of an auditory cortical channel can be plausibly described by a simple addition of the auditory and visual signals with saturation. (shrink)

In several experimental conditions, neuronal excitation at the perirhinal cortex (PC) does not propagate to the entorhinal cortex (EC) due to a “wall” of inhibition, which may help to create functional coupling and un‐coupling of the PC and EC in the medial temporal lobe. However, little is known regarding the coupling control process. Herein, we propose that the deep layer of area 35 in the PC plays a pivotal role in opening the gate for coupling, thus allowing the (...) activity in the PC to propagate to the EC. Using voltage‐sensitive dye imaging for the brain slices of rodents, we show that a slowly inactivating potassium conductance in this area is essential to induce excitation overtaking the inhibitory control. This coupling between the distinct neural circuits persists for at least 1 h. We elucidate further implications of this network‐level plastic behavior and its mechanism. (shrink)

Cortex functional connectivity associated with hypnosis was investigated in a single highly hypnotizable subject in a normal baseline condition and under neutral hypnosis during two sessions separated by a year. After the hypnotic induction, but without further suggestions as compared to the baseline condition, all studied parameters of local and remote functional connectivity were significantly changed. The significant differences between hypnosis and the baseline condition were observable (to different extent) in five studied independent frequency bands (delta, theta, alpha, beta, (...) and gamma). The results were consistent and stable after 1 year. Based on these findings we conclude that alteration in functional connectivity of the brain may be regarded as a neuronal correlate of hypnosis (at least in very highly hypnotizable subjects) in which separate cognitive modules and subsystems may be temporarily incapable of communicating with each other normally. (shrink)

The psychological and neurobiological processes underlying moral judgement have been the focus of many recent empirical studies1–11. Of central interest is whether emotions play a causal role in moral judgement, and, in parallel, how emotion-related areas of the brain contribute to moral judgement. Here we show that six patients with focal bilateral damage to the ventromedial prefrontal cortex (VMPC), a brain region necessary for the normal generation of emotions and, in particular, social emotions12–14, produce an abnor- mally ‘utilitarian’ pattern (...) of judgements on moral dilemmas that pit compelling considerations of aggregate welfare against highly emotionally aversive behaviours (for example, having to sacrifice one person’s life to save a number of other lives)7,8. In contrast, the VMPC patients’ judgements were normal in other classes of moral dilemmas. These findings indicate that, for a selective set of moral dilemmas, the VMPC is critical for normal judgements of right and wrong. The findings support a necessary role for emotion in the generation of those judgements. (shrink)

Moral judgments, whether delivered in ordinary experience or in the courtroom, depend on our ability to infer intentions. We forgive unintentional or accidental harms and condemn failed attempts to harm. Prior work demonstrates that patients with damage to the ventromedial prefrontal cortex deliver abnormal judgments in response to moral dilemmas and that these patients are especially impaired in triggering emotional responses to inferred or abstract events, as opposed to real or actual outcomes. We therefore predicted that VMPC patients would (...) deliver abnormal moral judgments of harmful intentions in the absence of harmful outcomes, as in failed attempts to harm. This prediction was confirmed in the current study: VMPC patients judged attempted harms, including attempted murder, as more morally permissible relative to controls. These results highlight the critical role of the VMPC in processing harmful intent for moral judgment. (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)

Posterior parietal cortex has traditionally been considered to be a sensory association area in which higher-order processing and intermodal integration of incoming sensory information occurs. In this paper, evidence from clinical reports and from lesion and behavioral-electrophysiological experiments using monkeys is reviewed and discussed in relation to the overall functional organization of posterior parietal association cortex, and particularly with respect to a proposed posterior parietal mechanism concerned with the initiation and control of certain classes of eye and limb (...) movements. Preliminary data from studies of the effects of posterior parietal lesions on oculomotor control in monkeys are reported.The behavioral effects of lesions of posterior parietal cortex in monkeys have been found to be similar to those which follow analogous damage of the minor hemisphere in humans, while behavioral-electrophysiological experiments have disclosed classes of neurons in this area which have functional properties closely related to the behavioral acts that are disrupted by lesions of the area. On the basis of current data from these areas of study, it is proposed that the sensory association model of posterior parietal function is inadequate to account for the complexities of the present evidence. Instead, it now appears that many diverse neural mechanisms are locatedin partin parietal cortex, that some of these mechanisms are involved in sensory processing and perceptual functions, but that others participate in motor control, and that still others are involved in attentional, motivational, or emotional processes. It is further proposed that the elementary units of these various neural mechanisms are distributed within posterior parietal cortex according to the columnar hypothesis of Mountcastle. (shrink)

A prefrontal control system that is less mature than the limbic reward system in adolescence is thought to impede self-regulatory abilities, which could contribute to poor dietary choices and obesity. We, therefore, aimed to examine whether structural morphology of the prefrontal cortex and the amygdala are associated with dietary decisions and obesity in children and adolescents. Seventy-one individuals between the ages of 8–22 years participated in this study; each participant completed a computer-based food choice task and a T1- and (...) T2-weighted structural brain scans. Two indices of obesity were assessed, including age- and sex-specific body mass index and waist-to-height ratio. The behavioral task included rating 60 food stimuli for tastiness, healthiness, and liking. Based on each participant’s self-ratings, 100 binary food choices were then made utilizing a computer mouse. Dietary “self-control” was calculated as the proportion of trials where the individual chose the healthier food item over the total number of trials. Cortical thickness and amygdala subnuclei volumes were quantified using FreeSurfer 6.0 and CIT168 atlas, respectively. We found that WHtR was negatively associated with the thickness of bilateral superior frontal, left superior temporal, right insula, and right inferior temporal regions. We also found WHtR to be positively associated with the volume of the central nucleus region of the amygdala, after adjusting for the hemisphere, age, sex, and intracranial volumes. A similar data pattern was observed when BMIz was used. Moreover, we found that across all participants, thinner right superior frontal cortex and larger left CEN volumes predicted lower dietary self-control. These results suggest that differential development of the PFC and amygdala relate to obesity and dietary self-control. Further longitudinal studies are merited to determine causal relationships among altered PFC to amygdala neural circuitry, dietary self-control, and obesity. (shrink)

The ventromedial prefrontal cortex (VMPFC) is crucial for moral behavior, yet the mechanism through which the VMPFC promotes moral behavior remains unclear. In this article, we emphasize that moral choice is often intertemporal, requiring foregoing short-term gains in favor of future outcomes of larger value. We propose that the VMPFC may be necessary for mental time travel (MTT), a cognitive process enabling vivid preexperiencing of future outcomes. By providing anticipated outcomes that inform decisions, MTT may promote farsighted, moral behaviors.

BackgroundNeuroimaging studies have shown a complex pattern of brain activation during perception of a pleasant odor and during its olfactory imagery. To date, little is known regarding changes in motor cortex excitability during these tasks. Bergamot essential oil is extensively used in perfumes and cosmetics for its pleasantness. Therefore, to further our understanding of the human sense of smell, this study aimed to investigate the effect of perception and imagery of a pleasant odor on motor cortex using Transcranial (...) magnetic stimulation.Materials and MethodsWe examined the primary motor cortex excitability during perception of a pleasant odor or perception of odorless saline. Furthermore, we tested the effect of olfactory imagery of BEO on corticospinal excitability. The increase in motor evoked potential amplitude was correlated with personality dimensions scores, pleasantness, vividness, and general imagery ability.ResultsThe results indicate that the corticospinal excitability changed after both perception and imagery of a pleasant odor. The correlation analysis shows an association with neuroticism personality trait and with general olfactory imagery ability.ConclusionBoth perception of a pleasant odor and its olfactory imagery modulate motor cortex excitability. The enhanced brain activation is affected by specific individual characteristics. Overall, our findings provide physiological evidence for a complex interaction between the olfactory and motor systems. (shrink)

Training under high interference conditions through interleaved practice results in performance suppression during training but enhances long-term performance relative to repetitive practice involving low interference. Previous neuroimaging work addressing this contextual interference effect of motor learning has relied heavily on the blood-oxygen-level-dependent response using functional magnetic resonance imaging methodology resulting in mixed reports of prefrontal cortex recruitment under IP and RP conditions. We sought to clarify these equivocal findings by imaging bilateral PFC recruitment using functional near-infrared spectroscopy while discrete (...) key pressing sequences were trained under IP and RP schedules and subsequently tested following a 24-h delay. An advantage of fNIRS over the fMRI BOLD response is that the former measures oxygenated and deoxygenated hemoglobin changes independently allowing for assessment of cortical hemodynamics even when there is neurovascular decoupling. Despite slower sequence performance durations under IP, bilateral PFC oxygenated and deoxygenated hemoglobin values did not differ between practice conditions. During test, however, slower performance from those previously trained under RP coincided with hemispheric asymmetry in PFC recruitment. Specifically, following RP, test deoxygenated hemoglobin values were significantly lower in the right PFC. The present findings contrast with previous behavioral demonstrations of increased cognitive demand under IP to illustrate a more complex involvement of the PFC in the contextual interference effect. IP and RP incur similar levels of bilateral PFC recruitment, but the processes underlying the recruitment are dissimilar. PFC recruitment during IP supports action reconstruction and memory elaboration while RP relies on PFC recruitment to maintain task variation information in working memory from trial to trial. While PFC recruitment under RP serves to enhance immediate performance, it does not support long-term performance. (shrink)

We applaud the spirit of MacNeilage's attempts to better explain the evolution and cortical control of speech by drawing on the vast literature in nonhuman primate neurobiology. However, he oversimplifies motor cortical fields and their known individual functions to such an extent that he undermines the value of his effort. In particular, MacNeilage has lumped together the functional characteristics across multiple mesial and lateral motor cortex fields, inadvertantly creating two hypothetical centers that simply may not exist.

Aggleton & Brown argue that the function of the hippocampus and perirhinal cortex can be dissociated along a spatial/nonspatial dimension. They further suggest that this division corresponds to a distinction between episodic and recognition memory. An analysis of the data, however, fails to support the underlying dissociation.

Painful stimuli evoke functional activations in the cortex, but electrical stimulation of these areas does not evoke pain sensation, nor does widespread epileptic discharge. Likewise, cortical lesions do not eliminate pain sensation. Although the cortex may contribute to pain modulation, the planning of escape responses, and learning, the network activity that constitutes the actual experience of pain probably occurs subcortically. (Published Online May 1 2007).

An alternative to Aggleton & Brown's interpretation is presented suggesting that the perirhinal cortex and hippocampus mediate different attribute information, but use the same processes, supporting the idea of parallel processing based on attribute (visual object and spatial location) rather than process characteristics (item recognition and familiarity).

I agree with the view expressed in the target article that the early structural organization of the mammalian neocortex (the primordial neocortical organization) is different from its final one and resembles the more primitive organization of reptilian cortex. During the early development of the neocortex, a distinctly mammalian multilayered pyramidal-cell plate is introduced within a more primitive reptilian-like cortex, establishing simultaneously layer I (marginal zone) above it and layer VII (subplate zone) below it. This multilayered pyramidal-cell plate represents (...) a recent mammalian innovation in the evolution of the cerebral cortex of vertebrates. Hence, the term neocortex is preferable to isocortex. (shrink)

Whether the prefrontal cortex is part of the neural substrates of consciousness is currently debated. Against prefrontal theories of consciousness, many have argued that neural activity in the prefrontal cortex does not correlate with consciousness but with subjective reports. We defend prefrontal theories of consciousness against this argument. We surmise that the requirement for reports is not a satisfying explanation of the difference in neural activity between conscious and unconscious trials, and that prefrontal theories of consciousness come out (...) of this debate unscathed. (shrink)

The anterior cingulate cortex (ACC)has been identified as part of a supervisoryattentional network for selecting alternativemotor programs in response to top-down corticalprocessing, particularly in situationsinvolving conflicting cognitive tasks.Bilateral lesions to the ACC may be causallyassociated with akinetic mutism, where patientsare unable to voluntarily initiate responses.The clinical and neuroanatomical evidence forthis presumed causal association is examined atlength. However, given the many reciprocalprojections between cerebral, motor, limbic andparalimbic structures within the executivesupervisory network, the association ofvoluntary behavior with a particular structure(the ACC) (...) is highly controversial and thereforepremature at this time. Also considered is theclaim that our subjective sense of voluntarycontrol and free will is simply due toour not having conscious access to theunderlying neural computations that precede our decisions and actions. On thecontrary, the distinction between voluntary and involuntary thoughts and actions mayrather be a matter of temporal and directionallag between parallel computations in differentneural areas. Finally, with reference toDennett, there is an extended discussion ofwhether patients with akinetic mutism are (i) conscious automata, (ii) non-intentional systems, and (iii) in azombie-like state. The relevance of (i)–(iii) for the cognitive neuroscientificliterature is then briefly addressed. (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)

BackgroundDuring the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation.ObjectiveThis study extends our previous findings by further characterizing how the brain differentially processes physical ‘touch’ stimulation and ‘imagined’ stimulation.DesignEleven healthy women participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and clitoris. Two additional conditions – imagined (...) dildo self-stimulation and imagined speculum stimulation – were included to characterize the effects of erotic versus non-erotic imagery.ResultsImagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule and the secondary somatosensory cortex. Imagined self-stimulation of the clitoris and nipp... (shrink)

During a migraine aura, patients experience sparkling, brilliant white light with vivid spectral colours — often described as shimmering, kaleidoscopic, and intrinsically beautiful. -/- The conventional production model claims that Cortical Spreading Depression (CSD) generates this light through spontaneous excitation in the visual cortex. However, this explanation suffers from a profound internal inconsistency. Extensive clinical evidence demonstrates that CSD consistently produces functional deficits wherever it travels: hemiparesis in the motor cortex, paresthesia in the somatosensory cortex, and aphasia (...) in language areas. It is illogical to posit that CSD produces functional loss everywhere except in the visual cortex, where it supposedly produces a gain of function — brilliant light. The logically consistent interpretation is that CSD causes functional failure in the visual cortex as well, and that this sparkling, brilliant inner light appears as a result of cortical silence. -/- Three independent and converging lines of neurophysiological evidence confirm this interpretation. First, MEG data show that alpha- and gamma-band rhythms collapse for the duration of the scintillations and return abruptly the moment they cease (Hall et al., 2004). Second, VEP studies show that the cortex no longer responds to external light during the aura (MacLean et al., 1975; Nyrke et al., 1989). Third, novel SEEG evidence (McLeod et al., 2025) offers the most direct confirmation to date: intracranial recording reveals a low-voltage suppression — a near-silent cortical signal — that correlates precisely with the scintillating scotoma. -/- The paper extends this reasoning along the CSD–TSD continuum, where Terminal Spreading Depolarization represents the permanent, irreversible form of CSD that occurs at death. A clarifying double dissociation is presented: retinal ischaemia (failure of the eye) leads to darkness, whereas cortical ischaemia (failure of the brain) leads to brilliant light. This pattern is consistent with the filter theory of consciousness (Bergson, 1896; Huxley, 1954; Kastrup, 2019), which holds that when the brain's filtering function fails, a broader, intrinsic dimension of experience is revealed — not produced, but uncovered. (shrink)

The posterior parietal cortex (PPC) is the most likely site where egocentric spatial relationships are represented in the brain. PPC cells receive visual, auditory, somaesthetic, and vestibular sensory inputs; oculomotor, head, limb, and body motor signals; and strong motivational projections from the limbic system. Their discharge increases not only when an animal moves towards a sensory target, but also when it directs its attention to it. PPC lesions have the opposite effect: sensory inattention and neglect. The PPC does not (...) seem to contain a “map” of the location of objects in space but a distributed neural network for transforming one set of sensory vectors into other sensory reference frames or into various motor coordinate systems. Which set of transformation rules is used probably depends on attention, which selectively enhances the synapses needed for making a particular sensory comparison or aiming a particular movement. (shrink)

Current views of the parietal cortex have difficulty accommodating the human inferior parietal lobe (IPL) within a simple dorsal versus ventral stream dichotomy. In humans, lesions of the right IPL often lead to syndromes such as hemispatial neglect that are seemingly in accord with the proposal that this region has a crucial role in spatial processing. However, recent imaging and lesion studies have revealed that inferior parietal regions have non-spatial functions, such as in sustaining attention, detecting salient events embedded (...) in a sequence of events and controlling attention over time. Here, we review these findings and show that spatial processes and the visual guidance of action are only part of the repertoire of parietal functions. Although sub-regions in the human superior parietal lobe and intraparietal sulcus contribute to vision-for-action and spatial functions, more inferior parietal regions have distinctly non-spatial attributes that are neither conventionally 'dorsal' nor conventionally 'ventral' in nature. (shrink)

A comprehensive and stimulating study which presents the views of 71 leading theorists on the underlying mechanisms and functions of the primary visual cortex.

On the basis of neuroiinaging studies, Posner & Raichle summarily report that the prefrontal cortex is involved in executive functioning and attention. In contrast to that superficial view, we briefly describe a testable model of the kinds of representations that are stored in prefrontal cortex, which, when activated, are expressed via plans, actions, thematic knowledge, and schemas.

The role of prefrontal cortex (PFC) in influencing creative thinking has been investigated by many researchers who, while succeeding in proving an effective involvement of PFC, reported suggestive but sometimes conflicting results. In order to better understand the relationships between creative thinking and brain activation in a more specific area of the PFC, we explored the role of dorsolateral PFC (DLPFC). We devised an experimental protocol using transcranial direct-current stimulation (tDCS). The study was based on a 3 (kind of (...) stimulation: anodal vs. cathodal vs. sham) × 2 (priming: divergent vs. convergent) design. Forty-five healthy adults were randomly assigned to one stimulation condition. Participants’ creativity skills were assessed using the Product Improvement subtest from the Torrance Tests of Creative Thinking (TTCT). After 20 min of tDCS stimulation, participants were presented with visual images of common objects. Half of the participants were instructed to visualize themselves using the object in an unusual way (divergent priming), whereas the other half were asked to visualize themselves while using the object in a common way (convergent priming). Priming was aimed at inducing participants to adopt different attitudes toward the creative task. Afterwards, participants were asked to describe all of the possible uses of the objects that were presented. Participants’ physiological activation was recorded using a biofeedback equipment. Results showed a significant effect of anodal stimulation that enhanced creative performance, but only after divergent priming. Participants showed lower skin temperature values after cathodal stimulation, a finding which is coherent with studies reporting that, when a task is not creative or creative thinking is not prompted, people show lower levels of arousal. Differences in individual levels of creativity as assessed by the Product Improvement test were not influential. The involvement of DLPFC in creativity has been supported, presumably in association to shift of attention modulated by priming. (shrink)

A key contention of Klein & Barron (2016) is that consciousness does not depend on cortical structures. A critical appraisal suggests they have overestimated the strength of their evidence.

Metacognition is the capacity to evaluate the success of one's own cognitive processes in various domains; for example, memory and perception. It remains controversial whether metacognition relies on a domain-general resource that is applied to different tasks or if self-evaluative processes are domain specific. Here, we investigated this issue directly by examining the neural substrates engaged when metacognitive judgments were made by human participants of both sexes during perceptual and memory tasks matched for stimulus and performance characteristics. By comparing patterns (...) of fMRI activity while subjects evaluated their performance, we revealed both domain-specific and domain-general metacognitive representations. Multivoxel activity patterns in anterior prefrontal cortex predicted levels of confidence in a domain-specific fashion, whereas domain-general signals predicting confidence and accuracy were found in a widespread network in the frontal and posterior midline. The demonstration of domain-specific metacognitive representations suggests the presence of a content-rich mechanism available to introspection and cognitive control. (shrink)

IntroductionThe prefrontal cortex plays a crucial role in cognition, particularly in executive functions. Cortical reactivity measured with Transcranial Magnetic Stimulation combined with Electroencephalography is altered in pathological conditions, and it may also be a marker of cognitive status in middle-aged adults. In this study, we investigated the associations between cognitive measures and TMS evoked EEG reactivity and explored whether the effects of this relationship were related to neurofilament light chain levels, a marker of neuroaxonal damage.MethodsFifty two healthy middle-aged adults (...) from the Barcelona Brain Health Initiative cohort underwent TMS-EEG, a comprehensive neuropsychological assessment, and a blood test for NfL levels. Global and Local Mean-Field Power, two measures of cortical reactivity, were quantified after left prefrontal cortex stimulation, and cognition was set as the outcome of the regression analysis. The left inferior parietal lobe was used as a control stimulation condition.ResultsLocal reactivity was significantly associated with working memory and reasoning only after L-PFC stimulation. No associations were found between NfL and cognition. These specific associations were independent of the status of neuroaxonal damage indexed by the NfL biomarker and remained after adjusting for age, biological sex, and education.ConclusionOur results demonstrate that TMS evoked EEG reactivity at the L-PFC, but not the L-IPL, is related to the cognitive status of middle-aged individuals and independent of NfL levels, and may become a valuable biomarker of frontal lobe-associated cognitive function. (shrink)

The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the (...) flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed. (shrink)

Argument The cerebral localization of mental functions is one of the centerpieces of modern brain research. Though the localization paradigm in its cultural and social interwovenness has been characterized as successful in the last third of the nineteenth century by a variety of historians of the neurosciences, there is also general agreement that localization came under threat around 1900. Besides the so-called holistic protest against the localization of mental functions, the neuroanatomical approach itself was challenged by experimental psychology, psychiatric nosology, (...) and psychoanalysis. This story underestimates the fact that anatomically-based localization remained powerful in response to these multiple challenges. This meant a neuroanatomical revision of tools, concepts, and practices. But this meant also a shift in the cultivation of the cortex from a more philosophical agenda to rather concrete political claims. More specifically, the idea of the cortex as the noblest part of man was supplemented by suggestions concerning its “Höherzüchtung.” I will analyze this re-orientation and radicalization in two steps. First, I briefly discuss the anatomical and philosophical account of Theodor Meynert and then turn to Paul Flechsig who in the late nineteenth century inscribed the ability to create culture and civilization into the cortex. Second, I focus on the neuroanatomists Oskar and Cécile Vogt, who began their careers around 1900 and expanded the cultivation of the cortex. Even before World War I, they proclaimed a “cerebral hygiene.” Consequently, the Vogts linked their innovative neuroanatomical researches with the rising field of genetics, racial hygiene, and eugenics. In the early Weimar Republic, the Vogts openly supported socialist ideas and were engaged in establishing an Institute for Brain Research in Soviet Moscow, where Lenin’s brain was analyzed. By the end of the Weimar Republic, the rhetoric of the Vogts was bluntly authoritarian. Based on a few anatomical examinations of so-called elite brains and the brains of criminals, they made concrete suggestions for eugenics and the breeding of “one-sidedly gifted leaders.” Given the remarkable popularity of the Vogts around 1930, their program is an important example of the hubris of predicting and guiding future developments on the basis of scientific authority. It can be regarded as an ironic nemesis that the Vogts – never sympathizing with the political aims of the National Socialists – were forced to finish their careers as influential Kaiser Wilhelm scientists in Nazi-Germany. Der Mensch wird immer mehr ein Hirntier werden. (Vogt 1912, 309). (shrink)

In this response, I offer some specific examples of neural workings, discuss the uncertainty of reverse inference, place neural reuse in developmental and cultural context, further differentiate reuse from plasticity, and clarify my position on embodied cognition. The concept of local neural workings is further refined, and some different varieties of reuse are identified. Finally, I lay out some opportunities for future research, and discuss some of the clinical implications of reuse in more detail.

The role of the prefrontal cortex is one of the most topical and important areas of research in contemporary neuropsychology. This cortical region appears to be linked with executive processes affecting many diverse areas of cognitive function. Working memory, information processing, behavioural organization, attention, judgement, and the ability to cope with novel experiences are just some of the diverse processes it affects. This book brings together contributions from some of the world's leading researchers on the prefrontal cortex. They (...) discuss the many recent theoretical and technical advances in the field - for example in our understanding of the neural architecture of the prefrontal cortex, in the development of comparable texts of cognition in humans and other primates, in our understanding of the relationships between neuronal activity and behaviour, and in the increasing use of functional neuroimaging to identify different levels of organization within the prefrontal cortex. These important developments make this an ideal time to address the many questions and debates that have arisen about the role and functional organization of this area of the brain. One of the first books to be written on the subject, The Prefrontal Cortex is a state-of-the-art account of our knowledge of this exciting subject. It will be welcomed by all researchers and students in neuro- and cognitive psychology, and neuroscience. (shrink)

In this commentary, the formation of “pre-iconic” visual-prime persistence is described in the context of prime-specific, independent-component activation at prefrontal and posterior EEG-recording sites. Although this activity subserves neural systems that are near identical to those described by Ruchkin and colleagues, we consider priming to be a dynamic process, identified with patterns of coherence and temporal structure of very high precision.