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Use of non-invasive brain stimulation methods (NIBS) has become a common approach to study social processing in addition to behavioural, imaging and lesion studies. However, research using NIBS to investigate social processing faces challenges. Overcoming these is important to allow valid and reliable interpretation of findings in neurotypical cohorts, but also to allow us to tailor NIBS protocols to atypical groups with social difficulties. In this review, we consider the utility of brain stimulation as a technique to study and modulate social processing. We also discuss challenges that face researchers using NIBS to study social processing in neurotypical adults with a view to highlighting potential solutions. Finally, we discuss additional challenges that face researchers using NIBS to study and modulate social processing in atypical groups. These are important to consider given that NIBS protocols are rarely tailored to atypical groups before use. Instead, many rely on protocols designed for neurotypical adults despite differences in brain function that are likely to impact response to NIBS.

Transcranial direct current stimulation (tDCS) and transcranial random noise stimulation (tRNS) have been claimed to produce many remarkable enhancements in perception, cognition, learning and numerous clinical conditions. The physiological basis of the claims for tDCS rests on the finding that 1 mA of unilateral anodal stimulation increases cortical excitation and 1 mA of cathodal produces inhibition. Here we show that these classic excitatory and inhibitory effects do not hold for the bilateral stimulation or 2 mA intensity conditions favoured in cognitive enhancement experiments. This is important because many, including some of the most salient claims are based on experiments using 2 mA bilateral stimulation. The claims for tRNS are also based on unilateral stimulation. Here we show that, again the classic excitatory effects of unilateral tRNS do not extend to the bilateral stimulation preferred in enhancement experiments. Further, we show that the effects of unilateral tRNS do not hold when one merely doubles the stimulation duration. We are forced to two conclusions: (i) that even if all the data on TES enhancements are true, the physiological explanations on which the claims are based are at best not established but at worst false, and (ii) that we cannot explain, scientifically at least, how so many experiments can have obtained data consistent with physiological effects that may not exist.

The development of the use of transcranial magnetic stimulation (TMS) in the study of psychological functions has entered a new phase of sophistication. This is largely due to an increasing physiological knowledge of its effects and to its being used in combination with other experimental techniques. This review presents the current state of our understanding of the mechanisms of TMS in the context of designing and interpreting psychological experiments. We discuss the major conceptual advances in behavioral studies using TMS. There are meaningful physiological and technical achievements to review, as well as a wealth of new perceptual and cognitive experiments. In doing so we summarize the different uses and challenges of TMS in mental chronometry, perception, awareness, learning, and memory.

International audience; Having investigated the effects of videos in the preceding chapter, this chapter assesses 2D animation, a form of presentation used in many coaching situations. The aim of this experiment was to investigate decision-making skills in different age groups (Under 16, 18 and 23) of elite academy footballers using a 2D animation simulation task of real game football scenarios. The work also explored the relationship between individual performance on the task and the actual performance on the pitch, as rated by three independent expert football coaches. This allowed us to examine whether this task is useful in predicting real-world decision-making skills. The results suggested that there was a significant difference between age groups on accuracy, by gaining more experience footballers perform better on the task. Also, the results showed a significant difference between all age groups on the response time. The under 23 age group were fastest, then the under 18 age group and finally the under 16 footballers were the slowest on the task. The correlation between performance on the task and the assessments provided by the coaches showed that 2D animation task is a sensitive measure in assessment of decision-making skills of elite academy players.

Aging adults typically show reduced ability to ignore task-irrelevant information, an essential skill for optimal performance in many cognitive operations, including those requiring working memory (WM) resources. In a first experiment, young and elderly human participants of both genders performed an established WM paradigm probing inhibitory abilities by means of valid, invalid, and neutral retro-cues. Elderly participants showed an overall cost, especially in performing invalid trials, whereas younger participants' general performance was comparatively higher, as expected.Inhibitory abilities have been linked to alpha brain oscillations but it is yet unknown whether in aging these oscillations (also typically impoverished) and inhibitory abilities are causally linked. To probe this possible causal link in aging, we compared in a second experiment parietal alpha-transcranial alternating current stimulation (tACS) with either no stimulation (Sham) or with two control stimulation frequencies (theta- and gamma-tACS) in the elderly group while performing the same WM paradigm. Alpha- (but not theta- or gamma-) tACS selectively and significantly improved performance (now comparable to younger adults' performance in the first experiment), particularly for invalid cues where initially elderly showed the highest costs. Alpha oscillations are therefore causally linked to inhibitory abilities and frequency-tuned alpha-tACS interventions can selectively change these abilities in the elderly.SIGNIFICANCE STATEMENTIgnoring task-irrelevant information, an ability associated to rhythmic brain activity in the alpha frequency band, is fundamental for optimal performance. Indeed, impoverished inhibitory abilities contribute to age-related decline in cognitive functions like working memory (WM), the capacity to briefly hold information in mind. Whether in aging adults alpha oscillations and inhibitory abilities arecausallylinked is yet unknown. We experimentally manipulated frequency-tuned brain activity using transcranial alternating current stimulation (tACS), combined with a retro-cue paradigm assessing WM and inhibition. We found that alpha-tACS induced a significant improvement in target responses and misbinding errors, two indexes of inhibition. We concluded that in aging alpha oscillations are causally linked to inhibitory abilities, and that despite being impoverished, these abilities are still malleable.

The spatial pattern of eye-movements to faces considered typical for neurologically healthy individuals is a roughly T-shaped distribution over the internal facial features with peak fixation density tending toward the left eye (observer’s perspective). However, recent studies indicate that striking deviations from this classic pattern are common within the population and are highly stable over time. The classic pattern actually reflects the average of these various idiosyncratic eye-movement patterns across individuals. The natural categories and respective frequencies of different types of idiosyncratic eye-movement patterns have not been specifically investigated before, so here we analyzed the spatial patterns of eye-movements for 48 participants to estimate the frequency of different kinds of individual eye-movement patterns to faces in the normal healthy population. Four natural clusters were discovered such that approximately 25% of our participants’ fixation density peaks clustered over the left eye region (observer’s perspective), 23% over the right eye-region, 31% over the nasion/bridge region of the nose, and 20% over the region spanning the nose, philthrum, and upper lips. We did not find any relationship between particular idiosyncratic eye-movement patterns and recognition performance. Individuals’ eye-movement patterns early in a trial were more stereotyped than later ones and idiosyncratic fixation patterns evolved with time into a trial. Finally, while face inversion strongly modulated eye-movement patterns, individual patterns did not become less distinct for inverted compared to upright faces. Group-averaged fixation patterns do not represent individual patterns well, so exploration of such individual patterns is of value for future studies of visual cognition.

Prismatic adaptation (PA) has been shown to affect left-to-right spatial representations of temporal durations. A leftward aftereffect usually distorts time representation toward an underestimation, while rightward aftereffect usually results in an overestimation of temporal durations. Here, we used functional magnetic resonance imaging (fMRI) to study the neural mechanisms that underlie PA effects on time perception. Additionally, we investigated whether the effect of PA on time is transient or stable and, in the case of stability, which cortical areas are responsible of its maintenance. Functional brain images were acquired while participants (n = 17) performed a time reproduction task and a control-task before, immediately after and 30 min after PA inducing a leftward aftereffect, administered outside the scanner. The leftward aftereffect induced an underestimation of time intervals that lasted for at least 30 min. The left anterior insula and the left superior frontal gyrus showed increased functional activation immediately after versus before PA in the time versus the control-task, suggesting these brain areas to be involved in the executive spatial manipulation of the representation of time. The left middle frontal gyrus showed an increase of activation after 30 min with respect to before PA. This suggests that this brain region may play a key role in the maintenance of the PA effect over time.

Faces and voices, in isolation, prompt consistent social evaluations. However, most human interactions involve both seeing and talking with another person. Our main goal was to investigate how facial and vocal information are combined to reach an integrated person impression. In Study 1, we asked participants to rate faces and voices separately for perceived trustworthiness, attractiveness, and dominance. Most previous studies relied on stimuli in which extra-vocal information (e.g., verbal content, prosody) may have confounded voice-based effects; to prevent these unwanted influences, we used brief, neutral vowel sounds. Voices, like faces, led to the formation of highly reliable impressions. Voice trustworthiness correlated with voice attractiveness, mirroring the relation between face trustworthiness and attractiveness, but did not correlate with voice dominance. Inconsistent with the possibility that face and voice evaluations are indicative of real character traits, we found no positive correlations between judgments of trustworthiness or dominance based on faces and the same judgments based on voices (there was also no correlation between face attractiveness and voice attractiveness). In Study 2, we asked participants to evaluate male targets after seeing their faces and hearing their voices. Faces and voices contributed equally to judgments of trustworthiness and combined to produce a significant interaction effect. For attractiveness, faces were given more weight than voices, possibly due to the predominantly visual character of the attractiveness concept (there was no interaction effect). For dominance, the reverse pattern was true, with voices having a larger effect than faces on final judgments. In this case the auditory cues may be perceived to be more reliable because of the strong links between voice pitch, masculinity, and dominance.

Background Slow Wave Activity (SWA), the low frequency (, Highlights • Cross-hemispheric tACS disrupted low frequency oscillation generation in afternoon nap. • Oscillation disruption correlated with declarative memory consolidation disruption. • Absent stimulation, low frequency oscillations also correlated with consolidation. • A rebound in low frequency oscillations was observed after 29 min of stimulation. • A causal role of low frequency oscillations in consolidation during nap is suggested.

Cognitive training aiming at improving learning is often successful, but what exactly underlies the observed improvements and how these differ across the age spectrum are currently unknown. Here we asked whether learning in young and older people may reflect enhanced ability to integrate information required to perform a cognitive task or whether it may instead reflect the ability to inhibit task-irrelevant information for successful task performance. We trained 30 young and 30 aging human participants on a numerosity discrimination task known to engage the parietal cortex and in which cue-integration and inhibitory abilities can be distinguished. We coupled training with parietal, motor, or sham transcranial random noise stimulation, known for modulating neural activity. Numerosity discrimination improved after training and was maintained long term, especially in the training + parietal stimulation group, regardless of age. Despite the quantitatively similar improvement in the two age groups, the content of learning differed remarkably: aging participants improved more in inhibitory abilities, whereas younger subjects improved in cue-integration abilities. Moreover, differences in the content of learning were reflected in different transfer effects to untrained but related abilities: in the younger group, improvements in cue integration paralleled improvements in continuous quantity (time and space), whereas in the elderly group, improvements in numerosity-based inhibitory abilities generalized to other measures of inhibition and corresponded to a decline in space discrimination, possibly because conflicting learning resources are used in numerosity and continuous quantity processing. These results indicate that training can enhance different, age-dependent cognitive processes and highlight the importance of identifying the exact processes underlying learning for effective training programs.

Background: Having investigated the influence of acute physical exhaustion on decision-making in world-class elite athletes in Parkin et al. (2017) , here a similar method is applied to subelite athletes. These subelite athletes were enrolled on a Team GB talent development program and were undergoing training for possible Olympic competition in 4–8 years. They differ from elite athletes examined previously according to expertise and age. While considered elite ( Swann et al., 2015 ), the subelite athletes had approximately 8 years fewer sporting experience and were yet to obtain sustained success on the international stage. Additionally, the average age of the subelite sample is 20 years; thus, they are still undergoing the behavioral, cognitive, and neuronal changes that occur during the transition from late adolescence to young adulthood ( Blakemore and Robbins, 2012 ). Previous work has used broad definitions of elite status in sport, and as such overlooked different categories within the spectrum of elite athletes ( Swann et al., 2015 ). Therefore it is important to consider subelite athletes as a discrete point on the developmental trajectory of elite sporting expertise. Objective: This work aims to investigate the influence of physical pressure on key indicators of decision-making in subelite athletes. It forms part of a wider project examining decision-making across different stages of the developmental trajectory in elite sport. In doing so, it aims to examine how to apply and develop psychological insights useful to an elite sporting environment. Methods: 32 subelite athletes (18 males, mean age: 20 years) participated in the study. Performance across three categories of decision-making was assessed under conditions of low and high physical pressure. Decision-making under risk was measured with performance of the Cambridge Gambling Task (CGT; Rogers et al., 1999 ), decision-making under uncertainty with the Balloon Analogue Risk Task (BART; Lejuez et al., 2002 ), and fast reactive responses and inhibition via the Stop Signal Reaction Time Task (SSRT; Logan, 1994 ). Physical exhaustion was induced via intervals of maximal exertion exercise on a wattbike. Results: Under pressure subelite athletes showed increased risk taking for both decisions where probability outcomes were explicit (on the CGT), and those where probability outcomes were unknown (on the BART). Despite making quicker decisions under pressure, with fewer errors, on the CGT, subelite athletes showed a reduced ability to optimally adjust betting behavior according to reward and loss contingencies. Fast reactive responses to perceptual stimuli and response inhibition did not change as a result of physical pressure. Individual responses to pressure showed a negative correlation in that a decrease in reaction times on the SSRT Task under pressure was associated with an increase in risk taking on the BART. When assessing the applicability of results based on group averages to individual athletes, 17% of the sample showed an “average” response (within 1 SD of the mean) to pressure across all three decision-making tasks. Conclusion: Indicators of decision-making in a sample of subelite athletes are influenced by physical pressure, with a shift toward increased indiscriminate risk taking. The influence that physical pressure has on decision-making was different to that observed in world-class elite athletes; this highlights the importance of distinguishing between athletes at the elite level ( Swann et al., 2015 ). The application of this work to a novel subgroup of elite athletes, including the implementation of a decision-making taxonomy, is discussed.

Background: Having investigated the decision making of world class elite and subelite athletes (see Parkin and Walsh, 2017 , Parkin et al., 2017 ), here the abilities of those at the earliest stage of entry to elite sport are examined. Junior elite athletes have undergone initial national selection and are younger than athletes examined previously (mean age 13 years). Decision making under mental pressure is explored in this sample. During performance an athlete encounters a wide array of mental pressures; these include the psychological impact of errors, negative feedback, and requirements for sustained attention in a dynamic environment ( Anshel and Wells, 2000 , Mellalieu et al., 2009 ). Such factors increase the cognitive demands of the athletes, inducing distracting anxiety-related thoughts known as rumination ( Beilock and Gray, 2007 ). Mental pressure has been shown to reduce performance of decision-making tasks where reward and loss contingencies are explicit, with a shift toward increased risk taking ( Pabst et al., 2013 , Starcke et al., 2011 ). Mental pressure has been shown to be detrimental to decision-making speed in comparison to physical stress, highlighting the importance of considering a range of different pressures encountered by athletes ( Hepler, 2015 ). Objective: To investigate the influence of mental pressure on key indicators of decision making in junior elite athletes. This chapter concludes a wider project examining decision making across developmental stages in elite sport. The work further explores how psychological insights can be applied in an elite sporting environment and in particular tailored to the requirements of junior athletes. Methods: Seventeen junior elite athletes (10 males, mean age: 13.80 years) enrolled on a national youth athletic development program participated in the study. Performance across three categories of decision making was assessed under conditions of low and high mental pressure. Decision making under risk was measured via the Cambridge Gambling Task (CGT; Rogers et al., 1999 ), decision making under uncertainty via the Balloon Analogue Risk Task (BART; Lejuez et al., 2002 ), and fast reactive responses to perceptual stimuli via the Visual Search Task ( Treisman, 1982 ). Mental pressure was induced with the addition of a concurrent verbal memory task, used to increase cognitive load and mimic the distracting effects of anxiety-related rumination. Results: In junior elite athletes, fast reactive responses to perceptual stimuli (on the Visual Search Task) were slower under conditions of mental pressure. For decision making under risk there was an interaction of mental pressure and gender on the amount of points gambled, under pressure there was a higher level of risk taking in male athletes compared to females. There was no influence of mental pressure on decision making under uncertainity. There were no significant correlations in the degree to which individual's responses changed under pressure across the three measures of decision making. When assessing the applicability of results based on group averages there were no junior elite athletes who showed an “average” response (within 1SD of the mean) to mental pressure across all the three decision-making tasks. Conclusion: Mental pressure affects decision making in a sample of junior elite athletes, with a slowing of response times, and modulations to performance of decision making under risk that have a high requirement for working memory. In relation to sport, these findings suggest that novel situations that place high cognitive demands on the athlete may be particularly influenced by mental pressure. The application of this work in junior elite athletes included the feedback of individual results and the implementation of a decision-making taxonomy.

People with synaesthesia not only have – by definition – unusual experiences (e.g., numbers triggering colour), they also have a different cognitive profile (e.g., in terms of their memory and perceptual abilities) and a bias towards certain interests and activities (e.g., towards the arts). However, virtually nothing is known about whether synaesthetes have an atypical personality profile. In this study, a standard measure of personality was administered (Big Five Inventory) along with two questionnaire measures of empathy. Synaesthetes, relative to demographically matched controls, reported higher levels of ‘Openness to Experience’ which is known to be related to imagination and artistic tendencies. They also reported higher levels of ‘Fantasizing’ on one of the empathy measures, which is conceptually related to Openness, although their self-reported empathy did not differ in other respects. In addition, synaesthetes reported lower levels of Agreeableness which we did not predict in advance.

In delay discounting tasks, participants decide between receiving a certain amount of money now or a larger sum sometime in the future. This study investigated the effects of transcranial direct current stimulation on delay discounting. Participants made delay discounting choices while receiving a bi-frontal stimulation of right-hemisphere anodal/left-hemisphere cathodal, left-hemisphere anodal/right-hemisphere cathodal, and sham stimulation, in three separate sessions. When the difference between the alternatives was 10% or more, participants generally preferred to wait for the larger sum. Nevertheless, there were more choices of smaller "immediate" gains, instead of the larger delayed options, when the left dorsolateral prefrontal cortex (DLPFC) was facilitated and the right DLPFC inhibited, compared to the sham stimulation. These observations indicate the significant role of the prefrontal cortex in delay discounting choices, and demonstrate that increased left frontal activation combined with decreased right frontal activation can alter decision-making by intensifying a tendency to choose immediate gains.

Numbers can be used to represent different meanings, including order information (‘Steve lives at house number 24’) and quantity (‘Steve is paid 24 pounds’). The few previous neuroimaging studies that investigated order and quantity processing reported conflicting evidence as to whether same or partially overlapping brain systems are engaged in these processes. Such inconsistencies may be related to the use of neuroimaging techniques which do not allow causal inference regarding brain-behaviour relationships. To overcome this problem, the present study employed continuous theta-burst stimulation (TBS) to investigate whether interference to either the left or right parietal regions affected order and quantity in similar or different ways. Results revealed that following TBS to the left intraparietal sulcus, quantity processing was impaired and order facilitated; TBS to the contralateral brain region led to no specific effects in either order or quantity processing. These findings suggest that there are at least partially different neuronal populations involved in order and quantity processing, and that the left parietal cortex is critical for both processes.

The ratio of the length of the 2nd and 4th digits of the hand is an indicator of prenatal testosterone exposure and has been shown to be a within sex correlate of various abilities, such as visuo-spatial processing in men. However, a number of studies report such links also exist in women, whilst others show no link for either sex. Using a unique paradigm that sub-divides visuo-spatial processing into a distinct subset of component skills we found a strong correlation between finger ratio and spatial memory performance specifically under stereo viewing conditions in women. We argue that the current ambiguity regarding links between digit-ratio and visuo-spatial ability is the result of a lack of clarity between the component skills recruited in different visuo-spatial tasks. Our task independently tested a subset of the component skills used in visuo-spatial tasks such as: mental rotation, cross-dimensionality processing and feature detection. Our results show that digit-ratio, a physical parameter linked to prenatal testosterone levels, indicates performance on a distinct aspect of visuo-spatial processing in women, without contradicting previous links for visuo-spatial processing in men. These results offer an explanation for the differences in previous findings linking visuo-spatial processing in both men and women.

The question why synaesthesia, an atypical binding within or between modalities, occurs is both enduring and important. Two explanations have been provided: (1) a congenital explanation: we are all born as synaesthetes but most of us subsequently lose the experience due to brain development; (2) a learning explanation: synaesthesia is related to some learning process during childhood. Three recent studies provide conflicting support for these explanations. Two studies supported the idea that synaesthesia is learned by showing that the frequency of everyday language implicitly modulates the synaesthetic experience. Another study argued that synaesthesia reflects basic, innate magnitude representations. In this paper we reassess these points of view, and show that it is possible for both to be valid. These findings are integrated into an interactive specialization account of development in order to explain the neuronal mechanism underlying synaesthesia.

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 V5 depends on the amount of activity in striate cortex (V1). From the timing and pattern of effects, we infer that back-projections from extrastriate cortex influence information content in V1, but it is V1 that determines whether that information reaches awareness.

The frontal eye fields (FEFs) and posterior parietal cortex (PPC) are important for target detection in conjunction visual search but the relative timings of their contribution have not been compared directly. We addressed this using temporally specific double pulse transcranial magnetic stimulation delivered at different times over FEFs and PPC during performance of a visual search task. Disruption of performance was earlier (0/40 ms) with FEF stimulation than with PPC stimulation (120/160 ms), revealing a clear and substantial temporal dissociation of the involvement of these two areas in conjunction visual search. We discuss these timings with reference to the respective roles of FEF and PPC in the modulation of extrastriate visual areas and selection of responses.

Improvement in performance following cognitive training is known to be further enhanced when coupled with brain stimulation. Here we ask whether training-induced changes can be maintained long term and, crucially, whether they can extend to other related but untrained skills. We trained overall 40 human participants on a simple and well established paradigm assessing the ability to discriminate numerosity-or the number of items in a set-which is thought to rely on an "approximate number sense" (ANS) associated with parietal lobes. We coupled training with parietal stimulation in the form of transcranial random noise stimulation (tRNS), a noninvasive technique that modulates neural activity. This yielded significantly better and longer lasting improvement (up to 16 weeks post-training) of the precision of the ANS compared with cognitive training in absence of stimulation, stimulation in absence of cognitive training, and cognitive training coupled to stimulation to a control site (motor areas). Critically, only ANS improvement induced by parietal tRNSTraining transferred to proficiency in other parietal lobe-based quantity judgment, i.e., time and space discrimination, but not to quantity-unrelated tasks measuring attention, executive functions, and visual pattern recognition. These results indicate that coupling intensive cognitive training with tRNS to critical brain regions resulted not only in the greatest and longer lasting improvement of numerosity discrimination, but importantly in this enhancement being transferable when trained and untrained abilities are carefully chosen to share common cognitive and neuronal components. © 2013 the authors.

“Priming of pop-out” is a form of implicit memory that facilitates detection of a recently inspected search target. Repeated presentation of a target's features or its spatial position improves detection speed (feature/spatial priming). This study investigated a role for the human frontal eye fields (FEFs) in the priming of color pop-out. To test the hypothesis that the FEFs play a role in short-term memory storage, transcranial magnetic stimulation (TMS) was applied during the intertrial interval. There was no effect of TMS on either spatial or feature priming. To test whether the FEFs are important when a saccade is being programmed to a repeated target color or location, TMS was applied during the search array. TMS over the left but not the right FEFs abolished spatial priming, but had no effect on feature priming. These findings demonstrate functional specialization of the left FEFs for spatial priming, and distinguish this role from target discrimination and saccade-related processes. The results suggest that the left FEFs integrate a spatial memory signal with an evolving saccade program, which facilitates saccades to a recently inspected location.

To determine the timing of visual processing in the early visual cortex, we applied single pulse transcranial magnetic stimulation to the occipital pole of healthy subjects while they were engaged in a forced-choice visual letter-identification task. We found two separate periods of activity, the first ranging from 20 to 60 ms after the onset of the visual stimulus, and the second ranging from 100 to 140 ms after the onset of the visual stimulus. We suggest that these two periods reflect necessary activity in V1, before and after re-entry.

Several published single case studies reveal a double dissociation between the effects of brain damage in separate extra-striate cortical visual areas on the perception of global visual motion defined by a difference in luminance (first-order motion) versus motion defined by a difference in contrast (second-order motion). In particular, the medial extrastriate cortical region V2/V3 seems to be crucial for the perception of first-order motion, but not for second-order, whereas a lateral and more anterior portion of the cortex close to the temporo-parieto-occipital junction (in the territory of the human motion area hV5/MT(+)) seems to be essential only for the perception of second-order motion. In order to test the hypothesis of a functional specialization of different visual areas for different types of motion, we applied repetitive transcranial magnetic stimulation (rTMS) unilaterally over areas V2/V3, V5/MT, or posterior parietal cortex (PPC) while subjects performed a 2AFC task with first- or second-order global motion displays in the contralateral visual field. Results showed a comparable disruption of the two types of motion, with both rTMS over V2/V3 or over MT/V5, and little or no effect with rTMS over PPC. The results suggest that either the previous psychophysical results with neurological patients are incorrect (highly unlikely) or that the lateral and medial regions are directly connected (as they are in macaque monkeys) such that stimulating one automatically affects the other, in this instance disruptively.

It is widely agreed that the right posterior parietal cortex has a preeminent role in visuospatial and orienting attention. A number of lines of evidence suggest that although orienting and the preparation of oculomotor responses are dissociable from each other, the two are intimately related. If this is true, then it should be possible to identify other attentional mechanisms tied to other response modalities. We used repetitive transcranial magnetic stimulation (rTMS) to demonstrate the existence of a distinct anterior parietal mechanism of motor attention. The critical area for motor attention is anterior to the one concerned with orienting, and it is lateralized to the left hemisphere in humans.

In their target article, Rips et al. have presented the view that there is no necessary dependency between natural numbers and internal magnitude. However, they do not give enough weight to neuroimaging and neuropsychological studies. We provide evidence demonstrating that the acquisition of natural numbers depends on magnitude representation and that natural numbers develop from a general magnitude mechanism in the parietal lobes.

The frontal eye fields (FEF) have typically been predominantly investigated in terms of their role in the generation of eye movements. Lesions to this area, either accidental or experimental, disrupt saccades and electrical stimulation elicits eye movements. Recently there has been increasing interest in the involvement of this area in visual processes, including in tasks where eye movements were either not required or were precluded. In addition to being involved in a range of visual tasks, evidence from visual search paradigms has suggested that this area might be important when the defining quality of the target is unpredictable or that it may be involved in priming. We investigated the role of FEF in a task requiring localisation of a target defined by colour, in which the target colour was either maintained or switched across trials. Disruption of performance was seen on the task when transcranial magnetic stimulation (TMS) was delivered over the left FEF, specifically elevating response times on trials when the target and distracter colours were switched rather than affecting any benefit of repetition of the target attribute (priming). This result is consistent with altered modulation of extrastriate areas, consequently affecting the speed with which a switch of the target colour could be detected. This both offers an explanation for effects seen in unpredictable feature search and is consistent with other TMS and microstimulation studies showing that FEF modulates responses of extrastriate cortex.

The Other-Race Effect (ORE) is the robust and well-established finding that people are generally poorer at facial recognition of individuals of another race than of their own race. Over the past four decades, much research has focused on the ORE because understanding this phenomenon is expected to elucidate fundamental face processing mechanisms and the influence of experience on such mechanisms. Several recent studies of the ORE in which the eye-movements of participants viewing own- and other-race faces were tracked have, however, reported highly conflicting results regarding the presence or absence of differential patterns of eye-movements to own- versus other-race faces. This discrepancy, of course, leads to conflicting theoretical interpretations of the perceptual basis for the ORE. Here we investigate fixation patterns to own- versus other-race (African and Chinese) faces for Caucasian participants using different analysis methods. While we detect statistically significant, though subtle, differences in fixation pattern using an Area of Interest (AOI) approach, we fail to detect significant differences when applying a spatial density map approach. Though there were no significant differences in the spatial density maps, the qualitative patterns matched the results from the AOI analyses reflecting how, in certain contexts, Area of Interest (AOI) analyses can be more sensitive in detecting the differential fixation patterns than spatial density analyses, due to spatial pooling of data with AOIs. AOI analyses, however, also come with the limitation of requiring a priori specification. These findings provide evidence that the conflicting reports in the prior literature may be at least partially accounted for by the differences in the statistical sensitivity associated with the different analysis methods employed across studies. Overall, our results suggest that detection of differences in eye-movement patterns can be analysis-dependent and rests on the assumptions inherent in the given analysis.

Cortical regions that respond preferentially to particular object categories, such as faces and bodies, are essential for visual perception of these object categories. However, precisely when these regions play a causal role in recognition of their preferred categories is unclear. Here we addressed this question using transcranial magnetic stimulation (TMS). Across a series of experiments, TMS was delivered over the functionally localized right occipital face area (rOFA) or right extrastriate body area (rEBA) at different latencies, up to 150 ms, after stimulus onset while adult human participants performed delayed match-to-sample tasks on face and body stimuli. Results showed that TMS disrupted task performance during two temporally distinct time periods after stimulus onset, the first at 40/50 ms and the second at 100/110 ms. These two time periods exhibited functionally distinct patterns of impairment: TMS delivered during the early time period (at 40/50 ms) disrupted task performance for both preferred (faces at rOFA and bodies at rEBA) and nonpreferred (bodies at rOFA and faces at rEBA) categories. In contrast, TMS delivered during the later time period (at 100/110 ms) disrupted task performance for the preferred category only of each area (faces at rOFA and bodies at rEBA). These results indicate that category-selective cortical regions are critical for two functionally distinct stages of visual object recognition: an early, presumably preparatory stage that is not category selective occurring almost immediately after stimulus onset, followed by a later stage of category-specific perceptual processing.

Transcranial direct current stimulation (tDCS) is a noninvasive method of modulating cortical excitability. The aim of this study was to investigate the effects of short-duration tDCS (1.6 seconds per trial) on memory performance, and whether the effects were affected by stimulation administered early or late in a trial. Participants memorize words under anodal and cathodal tDCS to the left dorsolateral prefrontal cortex (DLPFC) in two separate sessions in no-stimulation, early stimulation, and late stimulation trials. Early stimulation occurred during word presentation, whereas late stimulation occurred after word presentation. Early anodal tDCS led to significantly better accuracy and speed in a subsequent recognition test compared to anodal late or no-stimulation conditions. Early cathodal tDCS, on the other hand, led to significantly worse accuracy and speed in a subsequent recognition test compared with cathodal late or no-stimulation conditions. The results of this study suggest that short-duration tDCS can modulate memory performance and highlight the importance of period of stimulation.

Empathy is a multi-faceted concept consisting of our ability not only to share emotions but also to exert cognitive control and perspective taking in our interactions with others. Here we examined whether inter-individual variability in different components of empathy was related to differences in brain structure assessed using voxel-based morphometry. Following a magnetic resonance imaging (MRI) scan, participants completed the Interpersonal Reactivity Index (IRI). Multiple regression was then used to assess the relationship between individual differences in grey matter volume and individual differences in empathy traits. We found that individual differences in affective empathic abilities oriented towards another person were negatively correlated with grey matter volume in the precuneus, inferior frontal gyrus, and anterior cingulate. Differences in self-oriented affective empathy were negatively correlated with grey matter volume of the somatosensory cortex, but positively correlated with volume in the insula; cognitive perspective taking abilities were positively correlated with grey matter volume of the anterior cingulate; and the ability to empathise with fictional characters was positively related to grey matter changes in the right dorsolateral prefrontal cortex. These findings are discussed in relation to neurocognitive models of empathy., Highlights ► We studied how individual variability in empathy is linked to brain structure. ► Affective empathy was linked to changes in the precuneus and anterior cingulate. ► Changes in the inferior frontal gyrus were also linked with affective empathy. ► Perspective taking was related to changes in the anterior cingulate. ► Personal distress was linked to changes in the somatosensory cortex and insula.

The limits of human visual short-term memory (VSTM) have been well documented, and recent neuroscientific studies suggest that VSTM performance is associated with activity in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively charged electric current through the skull can rapidly and effortlessly improve people's VSTM performance. This artificial improvement, however, comes with an interesting twist: it interacts with people's natural VSTM capability such that low performers who tend to remember less information benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is explained by event-related potentials around the parietal regions: low performers showed increased waveforms in N2pc and contralateral delay activity (CDA), which implies improvement in attention deployment and memory access in the current paradigm, respectively. Interestingly, these components are found during the presentation of the test array instead of the retention interval, from the parietal sites ipsilateral to the target location, thus suggesting that transcranial direct current stimulation (tDCS) was mainly improving one's ability to suppress no-change distractors located on the irrelevant side of the display during the comparison stage. The high performers, however, did not benefit from tDCS as they showed equally large waveforms in N2pc and CDA, or SPCN (sustained parietal contralateral negativity), before and after the stimulation such that electrical stimulation could not help any further, which also accurately accounts for our behavioral observations. Together, these results suggest that there is indeed a fixed upper limit in VSTM, but the low performers can benefit from neurostimulation to reach that maximum via enhanced comparison processes, and such behavioral improvement can be directly quantified and visualized by the magnitude of its associated electrophysiological waveforms.

Cognitive training is an effective tool to improve a variety of cognitive functions, and a small number of studies have now shown that brain stimulation accompanying these training protocols can enhance their effects. In the domain of behavioral inhibition, little is known about how training can affect this skill. As for transcranial direct current stimulation (tDCS), it was previously found that stimulation over the right inferior frontal gyrus (rIFG) facilitates behavioral inhibition performance and modulates its electrophysiological correlates. This study aimed to investigate this behavioral facilitation in the context of a learning paradigm by giving tDCS over rIFG repetitively over four consecutive days of training on a behavioral inhibition task (stop signal task (SST)). Twenty-two participants took part; ten participants were assigned to receive anodal tDCS (1.5 mA, 15 min), 12 were assigned to receive training but not active stimulation. There was a significant effect of training on learning and performance in the SST, and the integration of the training and rIFG-tDCS produced a more linear learning slope. Better performance was also found in the active stimulation group. Our findings show that tDCS-combined cognitive training is an effective tool for improving the ability to inhibit responses. The current study could constitute a step toward the use of tDCS and cognitive training as a therapeutic tool for cognitive control impairments in conditions such as attention-deficit hyperactivity disorder (ADHD) or schizophrenia.

During priming of pop-out, performance at discriminating a pop-out feature target in visual search is affected by whether the target on the previous trial was defined by the same feature as on the upcoming trial. Recent studies suggest that priming of pop-out relies on attentional processes. With the use of simultaneous, combined transcranial magnetic stimulation and event-related potential recording (TMS-ERP), we tested for any critical role of the right angular gyrus (rANG) and left and right frontal eye fields (FEFs)—key attentional sites—in modulating both performance and the ERPs evoked by such visual events. Intertrial TMS trains were applied while participants discriminated the orientation of a color pop-out element in a visual search array. rANG TMS disrupted priming of pop-out, reducing reaction time costs on switch trials and speeding responses when the color of the pop-out target switched. rANG TMS caused a negativity in the ERP elicited in response to the visual stimulus array, starting 210 ms after stimulus onset. Both behavioral and ERP effects were apparent only after rANG TMS, on switch trials, and when the target in the visual search array was presented in the left visual field, with no effects after left or right FEF TMS. These results provide evidence for an attentional reorienting mechanism, which originates in the rANG and is modulated by the implicit memory of the previous trial. The rANG plays a causal role on switch trials during priming of pop-out by interacting with visual processing, particularly in the ipsilateral hemisphere representing the contralateral hemifield.

While the frontal eye fields (FEF) are traditionally associated with eye movements, recent work indicates possible roles in controlling selective visual processing. We applied 10 Hz bursts of transcranial magnetic stimulation (TMS) over left or right human FEF while subjects performed a partial-report task that allowed quantitative estimates of top-down control and other parameters affecting visual performance. Participants selectively reported digits in a relevant color (targets) but not those in an irrelevant color (nontargets) from a brief masked display. A target could appear alone or together with an accompanying item (nontarget or target) in the same or opposite hemifield. Targets were normally identified better when presented with a nontarget than with another target, indicating prioritization of task-relevant targets and thus top-down control. We found this usual pattern of results without TMS, and also with TMS over left FEF. However, during right FEF TMS, the detrimental impact of accompanying distractors increased. Formal analysis in terms of Bundesen's (1990) theory of visual attention confirmed that right FEF TMS diminished the top-down control parameter for both hemifields, indicating an FEF role in top-down selection even for targets defined by the nonspatial property of color. Direct comparison with our previous findings for parietal TMS (Hung et al., 2005) confirmed the distinct role of FEF in top-down control, plus right-hemisphere predominance for this in humans.

a b s t r a c t Stimulus inversion impairs face discrimination to a greater extent than discrimination of other non-face object categories. This finding has led to suggestions that upright faces are represented by mechanisms specialized for upright faces whereas inverted face representation depends on more general object recog- nition mechanisms. In the present study we tested the causal role of face-selective and object-selective cortical areas for upright and inverted face discrimination by transiently disrupting neural processing using transcranial magnetic stimulation (TMS). Participants matched upright and inverted faces while TMS was delivered over each participant's functionally localized right occipital face area (rOFA) or right lateral occipital area (rLO). TMS delivered over rOFA disrupted the discrimination of upright and inverted faces while TMS delivered over rLO impaired inverted face discrimination only. These results provide causal evidence that upright faces are represented by face-specific mechanisms whereas inverted faces are represented by both face-specific and object-specific mechanisms. The similar sensitivity of the OFA to upright and inverted faces is consistent with the hypothesis that the OFA processes facial features at an early stage of face processing.

The executive control of voluntary action involves not only choosing from a range of possible actions but also the inhibition of responses as circumstances demand. Recent studies have demonstrated that many clinical populations, such as people with attention-deficit hyperactivity disorder, exhibit difficulties in inhibitory control. One prefrontal area that has been particularly associated with inhibitory control is the pre-supplementary motor area (Pre-SMA). Here we applied non-invasive transcranial direct current stimulation (tDCS) over Pre-SMA to test its role in this behavior. tDCS allows for current to be applied in two directions to selectively excite or suppress the neural activity of Pre-SMA. Our results showed that anodal tDCS improved efficiency of inhibitory control. Conversely, cathodal tDCS showed a tendency towards impaired inhibitory control. To our knowledge, this is the first demonstration of non-invasive intervention tDCS altering subjects' inhibitory control. These results further our understanding of the neural bases of inhibitory control and suggest a possible therapeutic intervention method for clinical populations.

It has been argued that both modality-specific and supramodal mechanisms dedicated to time perception underlie the estimation of interval durations. While it is generally assumed that early sensory areas are dedicated to modality-specific time estimation, we hypothesized that early sensory areas such as the primary visual cortex or the auditory cortex might be involved in time perception independently of the sensory modality of the input. To test this possibility, we examined whether disruption of the primary visual cortex or the auditory cortex would disrupt time estimation of auditory stimuli and visual stimuli using transcranial magnetic stimulation (TMS). We found that disruption of the auditory cortex impaired not only time estimation of auditory stimuli but also impaired that of visual stimuli to the same degree. This finding suggests a supramodal role of the auditory cortex in time perception. On the other hand, TMS over the primary visual cortex impaired performance only in visual time discrimination. These asymmetric contributions of the auditory and visual cortices in time perception may be explained by a superiority of the auditory cortex in temporal processing. Here, we propose that time is primarily encoded in the auditory system and that visual inputs are automatically encoded into an auditory representation in time discrimination tasks.

Copyright © 2011 Society for Neuroscience and the authors. The The Journal of Neuroscience uses a Creative Commons Attribution-NonCommercial-ShareAlike licence: http://creativecommons.org/licenses/by-nc-sa/4.0/. Simulation models of expression recognition contend that to understand another's facial expressions, individuals map the perceived expression onto the same sensorimotor representations that are active during the experience of the perceived emotion. To investigate this view, the present study examines facial expression and identity recognition abilities in a rare group of participants who show facilitated sensorimotor simulation (mirror-touch synesthetes). Mirror-touch synesthetes experience touch on their own body when observing touch to another person. These experiences have been linked to heightened sensorimotor simulation in the shared-touch network (brain regions active during the passive observation and experience of touch). Mirror-touch synesthetes outperformed nonsynesthetic participants on measures of facial expression recognition, but not on control measures of face memory or facial identity perception. These findings imply a role for sensorimotor simulation processes in the recognition of facial affect, but not facial identity. The Medical Research Council, the Economic and Social Research Coucnil and the British Academy.

Our ability to recognize the emotions of others is a crucial feature of human social cognition. Functional neuroimaging studies indicate that activity in sensorimotor cortices is evoked during the perception of emotion. In the visual domain, right somatosensory cortex activity has been shown to be critical for facial emotion recognition. However, the importance of sensorimotor representations in modalities outside of vision remains unknown. Here we use continuous theta-burst transcranial magnetic stimulation (cTBS) to investigate whether neural activity in the right postcentral gyrus (rPoG) and right lateral premotor cortex (rPM) is involved in nonverbal auditory emotion recognition. Three groups of participants completed same-different tasks on auditory stimuli, discriminating between the emotion expressed and the speakers' identities, before and following cTBS targeted at rPoG, rPM, or the vertex (control site). A task-selective deficit in auditory emotion discrimination was observed. Stimulation to rPoG and rPM resulted in a disruption of participants' abilities to discriminate emotion, but not identity, from vocal signals. These findings suggest that sensorimotor activity may be a modality-independent mechanism which aids emotion discrimination. Copyright © 2010 the authors.

OBJECTIVE Recent developments in transcranial alternating current stimulation (tACS) provide a powerful approach to establish the functional roles of neuronal oscillatory activities in the human brain. Here, we investigated whether tACS can reach and modulate the excitability of the visual cortex in a frequency-dependent manner. METHODS We measured the cortical excitability of the visual cortex using single pulse transcranial magnetic stimulation (TMS) while delivering tACS to the occipital region at different frequencies (5, 10, 20 and 40 Hz). RESULTS We found that tACS at 20 Hz decreased TMS-phosphene threshold (i.e., increased the excitability of the visual cortex) during the stimulation, whereas other frequencies did not affect TMS-phosphene thresholds. CONCLUSIONS Our findings demonstrate direct interactions of tACS with the visual cortex in a frequency-dependent manner. SIGNIFICANCE Our present work provides further demonstration of the potential of tACS as a method to selectively modulate the excitability of the visual cortex.

Anticipating the timing of future events is a necessary precursor to preparing actions and allocating resources to sensory processing. This requires elapsed time to be represented in the brain and used to predict the temporal probability of upcoming events. While neuropsychological, imaging, magnetic stimulation studies, and single-unit recordings implicate the role of higher parietal and motor-related areas in temporal estimation, the role of earlier, purely sensory structures remains more controversial. Here we demonstrate that the temporal probability of expected visual events is encoded not by a single area but by a wide network that importantly includes neuronal populations at the very earliest cortical stages of visual processing. Moreover, we show that activity in those areas changes dynamically in a manner that closely accords with temporal expectations.

When faced with inconclusive or conflicting visual input human observers experience one of multiple possible perceptions. One factor that determines perception of such an ambiguous stimulus is how the same stimulus was perceived on previous occasions, a phenomenon called perceptual memory. We examined perceptual memory of an ambiguous motion stimulus while applying transcranial magnetic stimulation (TMS) to the motion-sensitive areas of the middle temporal cortex (hMT+). TMS increased the predominance of whichever perceptual interpretation was most commonly reported by a given observer at baseline, with reduced perception of the less favored interpretation. This increased incidence of the preferred percept indicates impaired long-term buildup of perceptual memory traces that normally act against individual percept biases. We observed no effect on short-term memory traces acting from one presentation to the next. Our results indicate that hMT+ is important for the long-term buildup of perceptual memory for ambiguous motion stimuli.

Based on neuroimaging methods, it is a commonly held view that numerical representation in the human parietal lobes is format independent. We used a transcranial magnetic stimulation adaptation paradigm to examine the existence of functionally segregated overlapping populations of neurons for different numerical formats and to reveal how numerical information is encoded and represented. Based on 2 experiments, we found that right parietal lobe stimulation showed a dissociation between digits and verbal numbers, whereas the left parietal lobe showed a double dissociation between the different numerical formats. Further analysis and modeling also excluded pre- or postrepresentational components as the source of the current effects. These results demonstrate that both parietal lobes are equipped with format-dependent neurons that encode quantity.

Human neuroimaging studies have implicated a number of brain regions in long-term memory formation. Foremost among these is ventrolateral prefrontal cortex. Here, we used double-pulse transcranial magnetic stimulation (TMS) to assess whether the contribution of this part of cortex is crucial for laying down new memories and, if so, to examine the time course of this process. Healthy adult volunteers performed an incidental encoding task (living/nonliving judgments) on sequences of words. In separate series, the task was performed either on its own or while TMS was applied to one of two sites of experimental interest (left/right anterior inferior frontal gyrus) or a control site (vertex). TMS pulses were delivered at 350, 750, or 1,150 ms following word onset. After a delay of 15 min, memory for the items was probed with a recognition memory test including confidence judgments. TMS to all three sites nonspecifically affected the speed and accuracy with which judgments were made during the encoding task. However, only TMS to prefrontal cortex affected later memory performance. Stimulation of left or right inferior frontal gyrus at all three time points reduced the likelihood that a word would later be recognized by a small, but significant, amount (∼4%). These findings indicate that bilateral ventrolateral prefrontal cortex plays an essential role in memory formation, exerting its influence between ≥350 and 1,150 ms after an event is encountered.

Our experience of time is unlike that of other features of the sensory world such as colour, movement, touch, or sound because there is no unique receptor system through which it is received. However, since time can be perceived, remembered, estimated, and compared in a way analogous to other sensory experiences, it should perhaps be subject to some of the same architectures or principles that have advanced understanding in these other domains. By adapting a task designed to test visual memory within a perception/action framework we investigated whether memory for time is affected by the use to which temporal information is put. When remembering a visual or auditory duration for subsequent motor production, storage is biased by a delay of up to 8 s. When the same duration is remembered for subsequent perception, however, there is no such effect of delay on memory. The results suggest a distinction in temporal memory that parallels the perception/action dichotomy in vision.

The study of neuronal specialisation in different cognitive and perceptual domains is important for our understanding of the human brain, its typical and atypical development, and the evolutionary precursors of cognition. Central to this understanding is the issue of numerical representation, and the question of whether numbers are represented in an abstract fashion. Here we discuss and challenge the claim that numerical representation is abstract. We discuss the principles of cortical organisation with special reference to number and also discuss methodological and theoretical limitations that apply to numerical cognition and also to the field of cognitive neuroscience in general. We argue that numerical representation is primarily non-abstract and is supported by different neuronal populations residing in the parietal cortex.

The commentators have raised many pertinent points that allow us to refine and clarify our view. We classify our response comments into seven sections: automaticity; developmental and educational questions; priming; multiple representations or multiple access(?); terminology; methodological advances; and simulated cognition and numerical cognition. We conclude that the default numerical representations are not abstract.

The development of sub-disciplines within cognitive neuroscience follows common sense categories such as language, audition, action, memory, emotion and perception among others. There are also well-established research programmes into temporal perception, spatial perception and mathematical cognition that also reflect the subjective impression of how experience is constructed. There is of course no reason why the brain should respect these common sense, text book divisions and, here, we discuss the contention that generalized magnitude processing is a more accurate conceptual description of how the brain deals with information about time, space, number and other dimensions. The roots of the case for linking magnitudes are based on the use to which magnitude information is put (action), the way in which we learn about magnitudes (ontogeny), shared properties and locations of magnitude processing neurons, the effects of brain lesions and behavioural interference studies. Here, we assess this idea in the context of a theory of magnitude, which proposed common processing mechanisms of time, space, number and other dimensions.