Occipitotemporal Regions Research Articles

Acute exercise, memory, and neural activation in young adults

Acute exercise benefits memory, and the temporal placement of exercise relative to exposure can affect the magnitude of benefits observed. Although the temporal placement appears to be important, there is a limited understanding as to how cognitive benefits in response to acute exercise are achieved. Hence, we conducted a two-part study including a behavioral study and a follow-up functional magnetic resonance imaging (fMRI) study to advance our understanding of the potential role of the effects of exercise on memory and neural activation. For Study One, we assessed the effect of acute exercise on memory in young adults. Participants were randomized to exercise before exposure for 20 min (before only, BO), after exposure for 20 min (After Only, AO), before and after exposure for 10 min at each time (before and after, BA), or to receive no exercise (No-exercise Control, NC). Similar to previous findings, any exercise prior to exposure (BO, BA) benefited some aspects of memory performance. Interestingly, the more consistent and larger benefits were seen with a shorter duration of exercise both before and after exposure (BA). Study Two replicated the methods of Study One comparing the BA condition (which had the most robust benefits) to the NC condition while collecting fMRI data during the memory task. Analyses assessed condition differences of activation during encoding and recall. There were no condition differences during memory encoding, however there was a condition effect on activation in occipito-temporal regions during the memory recall trials. Consistent with previous research, exercise appears to benefit memory with some exercise prior to exposure being important for the benefits achieved. Further, exercise affects neural activation and the results appear complementary to the behavior findings. Future research should use a within-subjects design to control for heterogeneity in behavior and neural activation.

Theory of mind in schizotypy: A behavioral and event-related potential (ERP) study

BackgroundSchizophrenia is known for their theory of mind (ToM) impairment. However, this impairment in schizotypy (schizotypal traits) lacks investigation. AimsThe present study investigated: (1) whether ToM ability was impaired in schizotypy; (2) whether the ERP amplitudes in nine brain regions of interest associated with ToM (e.g., frontal region) in schizotypy and healthy controls differed; and (3) whether the relationship between ToM performances and ERP amplitudes in schizotypy differed from that in healthy controls. MethodForty eight adolescents and young adults (16 schizotypy) with the mean age of 18 years were tested. The Reading the Mind in the Eyes Test (RMET) was used to assess their ToM during which ERP amplitudes were recorded. ResultsThe schizotypy group showed significantly lower ERP amplitudes in all conditions of RMET in frontal, frontal-central, central, occipital and temporal regions when compared to those in healthy controls. Also, schizotypy's ERP amplitudes in the frontal, frontal-central, central, occipital, and temporal regions were different from those in the healthy individuals in responding to different types of ToM stimuli (positive, negative and neutral). In schizotypy group, reaction time responding to emotional stimuli was negatively related to ERP amplitudes in the frontal, central-parietal, parietal, occipital, and occipito-temporal regions during RMET while no significant correlations were found in healthy controls. ConclusionThe present findings inform us with the knowledge regarding the neural and behavioral abnormality of ToM in schizotypy, suggesting that brain activity can be an alternative to detect ToM impairment in schizotypy.

A novel phenotype of 13q12.3 microdeletion characterized by epilepsy in an Asian child: a case report

BackgroundThe microdeletion of chromosome 13 has been rarely reported. Here, we report a 14-year old Asian female with a de novo microdeletion on 13q12.3.Case presentationThe child suffered mainly from two types of epileptic seizures: partial onset seizures and myoclonic seizures, accompanied with intellectual disability, developmental delay and minor dysmorphic features. The electroencephalogram disclosed slow waves in bilateral temporal, together with generalized spike-and-slow waves, multiple-spike-and-slow waves and slow waves in bilateral occipitotemporal regions. The exome sequencing showed no pathogenic genetic variation in the patient’s DNA sample. While the single nucleotide polymorphism (SNP) array analysis revealed a de novo microdeletion spanning 2.324 Mb, within the cytogenetic band 13q12.3.ConclusionsThe epilepsy may be associated with the mutation of KATNAL1 gene or the deletion unmasking a recessive mutation on the other allele, and our findings could provide a phenotypic expansion.

Mental rotation ability and spontaneous brain activity: a magnetoencephalography study.

We performed experiments using magnetoencephalography to clarify the relationship between three-dimensional visuospatial abilities and spontaneous visual thinking characteristics. Subjects were divided into two groups based on the rate of correct answers to mental rotation tasks: those with good performances (Group G) and those with bad performances (Group B). We found the followings: (1) in the mental rotation tasks, the 25-35 Hz lower γ band activities in the superior parietal lobule/intraparietal sulcus regions and in the occipitotemporal region were significantly larger in Group G than in Group B and (2) in the spontaneous mental imagery tasks, the 20-Hz band activity in the left premotor cortex and the 35-Hz band activity in the supplementary motor area were significantly larger in Group G.

A robust neural familiar face recognition response in a dynamic (periodic) stream of unfamiliar faces

We present an objective and sensitive approach to measure human familiar face recognition (FFR) across variable facial identities. Twenty-six participants viewed sequences of natural images of different unfamiliar faces presented at a fixed rate of 6 Hz (i.e., 6 faces by second), with variable natural images of different famous face identities appearing periodically every 7th image (i.e., .86 Hz). Participants were unaware of the goal of the study and performed an orthogonal task. Following only seven minutes of visual stimulation, the FFR response was objectively identified in the EEG spectrum at .86 Hz and its harmonics (1.71 Hz, etc.) over bilateral occipito-temporal regions, being significant in every individual participant. When the exact same images appeared upside-down, the FFR response amplitude reduced by more than 80%, and was uncorrelated across individuals to the upright face response. The FFR for upright faces emerges between 160 and 200 msec following the famous face onset over bilateral occipito-temporal region and lasts until about 560 msec. The stimulation paradigm offers an unprecedented way to characterize rapid and automatic human face familiarity recognition across individuals, during development and clinical conditions, also providing original information about the time-course and neural basis of human FFR in temporally constrained stimulation conditions with natural images.

Long-lasting connectivity changes induced by intensive first-person shooter gaming.

Action videogames have been shown to induce modifications in perceptual and cognitive systems, as well as in brain structure and function. Nevertheless, whether such changes are correlated with brain functional connectivity modifications outlasting the training period is not known. Functional magnetic resonance imaging (fMRI) was used in order to quantify acute and long-lasting connectivity changes following a sustained gaming experience on a first-person shooter (FPS) game. Thirty-five healthy participants were assigned to either a gaming or a control group prior to the acquisition of resting state fMRI data and a comprehensive cognitive assessment at baseline (T0), post-gaming (T1) and at a 3months' follow-up (T2). Seed-based resting-state functional connectivity (rs-FC) analysis revealed a significant greater connectivity between left thalamus and left parahippocampal gyrus in the gamer group, both at T1 and at T2. Furthermore, a positive increase in the rs-FC between the cerebellum, Heschl's gyrus and the middle frontal gyrus paralleled improvements of in-gaming performance. In addition, baseline rs-FC of left supramarginal gyrus, left middle frontal gyrus and right cerebellum were associated with individual changes in videogame performance. Finally, enhancement of perceptual and attentional measures was observed at both T1 and T2, which correlated with a pattern of rs-FC changes in bilateral occipito-temporal regions belonging to the visual and attention fMRInetworks. The present findings increase knowledge on functional connectivity changes induced by action videogames, pointing to a greater and long-lasting synchronization between brain regions associated with spatial orientation, visual discrimination and motor learning even after a relatively short multi-day gaming exposure.

Shared and distinct functional networks for empathy and pain processing: a systematic review and meta-analysis of fMRI studies.

BackgroundEmpathy for pain is a complex phenomenon incorporating sensory, cognitive and affective processes. Functional neuroimaging studies indicate a rich network of brain activations for empathic processing. However, previous research focused on core activations in bilateral anterior insula (AI) and anterior cingulate/anterior midcingulate cortex (ACC/aMCC) which are also typically present during nociceptive (pain) processing. Theoretical understanding of empathy would benefit from empirical investigation of shared and contrasting brain activations for empathic and nociceptive processing.MethodThirty-nine empathy for observed pain studies (1112 participants; 527 foci) were selected by systematic review. Coordinate based meta-analysis (activation likelihood estimation) was performed and novel contrast analyses compared neurobiological processing of empathy with a comprehensive meta-analysis of 180 studies of nociceptive processing (Tanasescu et al., 2016).ResultsConjunction analysis indicated overlapping activations for empathy and nociception in AI, aMCC, somatosensory and inferior frontal regions. Contrast analysis revealed increased likelihood of activation for empathy, relative to nociception, in bilateral supramarginal, inferior frontal and occipitotemporal regions. Nociception preferentially activated bilateral posterior insula, somatosensory cortex and aMCC.ConclusionOur findings support the likelihood of shared and distinct neural networks for empathic, relative to nociceptive, processing. This offers succinct empirical support for recent tiered or modular theoretical accounts of empathy.

Differential activation of the visual word form area during auditory phoneme perception in youth with dyslexia

Developmental dyslexia is a learning disorder characterized by difficulties reading words accurately and/or fluently. Several behavioral studies have suggested the presence of anomalies at an early stage of phoneme processing, when the complex spectrotemporal patterns in the speech signal are analyzed and assigned to phonemic categories. In this study, fMRI was used to compare brain responses associated with categorical discrimination of speech syllables (P) and acoustically matched nonphonemic stimuli (N) in children and adolescents with dyslexia and in typically developing (TD) controls, aged 8–17 years. The TD group showed significantly greater activation during the P condition relative to N in an area of the left ventral occipitotemporal cortex that corresponds well with the region referred to as the “visual word form area” (VWFA). Regression analyses using reading performance as a continuous variable across the full group of participants yielded similar results. Overall, the findings are consistent with those of previous neuroimaging studies using print stimuli in individuals with dyslexia that found reduced activation in left occipitotemporal regions; however, the current study shows that these activation differences seen during reading are apparent during auditory phoneme discrimination in youth with dyslexia, suggesting that the primary deficit in at least a subset of children may lie early in the speech processing stream and that categorical perception may be an important target of early intervention in children at risk for dyslexia.

Longitudinal neuroimaging biomarkers differ across Alzheimer's disease phenotypes.

Alzheimer's disease can present clinically with either the typical amnestic phenotype or with atypical phenotypes, such as logopenic progressive aphasia and posterior cortical atrophy. We have recently described longitudinal patterns of flortaucipir PET uptake and grey matter atrophy in the atypical phenotypes, demonstrating a longitudinal regional disconnect between flortaucipir accumulation and brain atrophy. However, it is unclear how these longitudinal patterns differ from typical Alzheimer's disease, to what degree flortaucipir and atrophy mirror clinical phenotype in Alzheimer's disease, and whether optimal longitudinal neuroimaging biomarkers would also differ across phenotypes. We aimed to address these unknowns using a cohort of 57 participants diagnosed with Alzheimer's disease (18 with typical amnestic Alzheimer's disease, 17 with posterior cortical atrophy and 22 with logopenic progressive aphasia) that had undergone baseline and 1-year follow-up MRI and flortaucipir PET. Typical Alzheimer's disease participants were selected to be over 65 years old at baseline scan, while no age criterion was used for atypical Alzheimer's disease participants. Region and voxel-level rates of tau accumulation and atrophy were assessed relative to 49 cognitively unimpaired individuals and among phenotypes. Principal component analysis was implemented to describe variability in baseline tau uptake and rates of accumulation and baseline grey matter volumes and rates of atrophy across phenotypes. The capability of the principal components to discriminate between phenotypes was assessed with logistic regression. The topography of longitudinal tau accumulation and atrophy differed across phenotypes, with key regions of tau accumulation in the frontal and temporal lobes for all phenotypes and key regions of atrophy in the occipitotemporal regions for posterior cortical atrophy, left temporal lobe for logopenic progressive aphasia and medial and lateral temporal lobe for typical Alzheimer's disease. Principal component analysis identified patterns of variation in baseline and longitudinal measures of tau uptake and volume that were significantly different across phenotypes. Baseline tau uptake mapped better onto clinical phenotype than longitudinal tau and MRI measures. Our study suggests that optimal longitudinal neuroimaging biomarkers for future clinical treatment trials in Alzheimer's disease are different for MRI and tau-PET and may differ across phenotypes, particularly for MRI. Baseline tau tracer retention showed the highest fidelity to clinical phenotype, supporting the important causal role of tau as a driver of clinical dysfunction in Alzheimer's disease.

The Effective Brain Areas in Recognition of Dyslexia

Background: The brain has four lobes consist of frontal, parietal, occipital, and temporal. Most researchers have reported that the left occipitotemporal region of the brain, which is the combined region of the occipital and temporal lobes, is less active in children with dyslexia like Sklar, Glaburda, Ashkenazi and Leisman. Methods: There are different methods and tools to investigate how the brain works, such as magnetic resonance imaging (MRI), positron emission tomography (PET), magneto-encephalography (MEG) and electroencephalography (EEG). Among these, EEG determines the electrical activity of the brain with the electrodes placed on the special areas on the scalp. In this research, we processed the EEG signals of dyslexic children and healthy ones to determine what the areas of the brain are most likely to cause the disease. Results: For this purpose, we extracted 43 features, including relative spectral power (RSP) features, mean, standard deviation, skewness, kurtosis, Hjorth, and AR parameters. Then an SVM classifier is used to separate two classes. Finally, we show the particular brain activation pattern by calculating the correlation coefficients and co-occurrence matrices, which suggests the activation of the working memory region as an active area. Conclusion: By identifying the brain areas involved in reading activity, it has expected that psychologists and physicians will be able to design the therapeutic exercises to activate this part of the brain.

Shared Representation of Visual and Auditory Motion Directions in the Human Middle-Temporal Cortex

The human occipito-temporal region hMT+/V5 is well known for processing visual motion direction. Here, we demonstrate that hMT+/V5 also represents the direction of auditory motion in a format partially aligned with the one used to code visual motion. We show that auditory and visual motion directions can be reliably decoded in individually localized hMT+/V5 and that motion directions in one modality can be predicted from the activity patterns elicited by the other modality. Despite shared motion-direction information across the senses, vision and audition, however, overall produce opposite voxel-wise responses in hMT+/V5. Our results reveal a multifaced representation of multisensory motion signals in hMT+/V5 and have broader implications for our understanding of how we consider the division of sensory labor between brain regions dedicated to a specific perceptual function.

Using the force: STEM knowledge and experience construct shared neural representations of engineering concepts

How does STEM knowledge learned in school change students’ brains? Using fMRI, we presented photographs of real-world structures to engineering students with classroom-based knowledge and hands-on lab experience, examining how their brain activity differentiated them from their “novice” peers not pursuing engineering degrees. A data-driven MVPA and machine-learning approach revealed that neural response patterns of engineering students were convergent with each other and distinct from novices’ when considering physical forces acting on the structures. Furthermore, informational network analysis demonstrated that the distinct neural response patterns of engineering students reflected relevant concept knowledge: learned categories of mechanical structures. Information about mechanical categories was predominantly represented in bilateral anterior ventral occipitotemporal regions. Importantly, mechanical categories were not explicitly referenced in the experiment, nor does visual similarity between stimuli account for mechanical category distinctions. The results demonstrate how learning abstract STEM concepts in the classroom influences neural representations of objects in the world.

Application of long-interval paired-pulse transcranial magnetic stimulation to motion-sensitive visual cortex does not lead to changes in motion discrimination

The perception of visual motion is dependent on a set of occipitotemporal regions that are readily accessible to neuromodulation. The current study tested if paired-pulse Transcranial Magnetic Stimulation (ppTMS) could modulate motion perception by stimulating the occipital cortex as participants viewed near-threshold motion dot stimuli. In this sham-controlled study, fifteen subjects completed two sessions. On the first visit, resting motor threshold (RMT) was assessed, and participants performed an adaptive direction discrimination task to determine individual motion sensitivity. During the second visit, subjects performed the task with three difficulty levels as TMS pulses were delivered 150 and 50 ms prior to motion stimulus onset at 120% RMT, under the logic that the cumulative inhibitory effect of these pulses would alter motion sensitivity. ppTMS was delivered at one of two locations: 3 cm dorsal and 5 cm lateral to inion (scalp-based coordinate), or at the site of peak activation for “motion” according to the NeuroSynth fMRI database (meta-analytic coordinate). Sham stimulation was delivered on one-third of trials by tilting the coil 90°. Analyses showed no significant active-versus-sham effects of ppTMS when stimulation was delivered to the meta-analytic (p = 0.15) or scalp-based coordinates (p = 0.17), which were separated by 29 mm on average. Active-versus-sham stimulation differences did not interact with either stimulation location (p = 0.12) or difficulty (p = 0.33). These findings fail to support the hypothesis that long-interval ppTMS recruits inhibitory processes in motion-sensitive cortex but must be considered within the limited parameters used in this design.

The Neural Consequences of Attentional Prioritization of Internal Representations in Visual Working Memory.

Although humans can hold multiple items in mind simultaneously, the contents of working memory (WM) can be selectively prioritized to guide future behavior. We explored whether the "same-object" benefits in visual processing may also be observed in visual WM. fMRI data were collected while participants performed a multistep serial retrocuing task in which they first viewed two 2-D objects (coherently moving colored dots). During retention, an initial relevance cue then indicated whether only the first or only the second object ("object-relevant"), or only the color of both objects or only their direction of motion would be relevant for the remainder of the trial ("feature-relevant"). On "object-relevant" trials, the ensuing priority cues selected either one of the features ("color" or "direction") bound to the relevance-cued object, whereas on "feature-relevant" trials, the priority cues selected one of the two relevance-cued features. Using multivariate inverted encoding models, we found a same-object benefit on object-relevant trials in occipitotemporal regions: On feature-relevant trials, the first priority cue triggered a strengthening of the neural representation of the cued feature and a concomitant weakening to baseline of the uncued feature, whereas on object-relevant trials, the cued item remained active but did not increase in strength and the uncued item weakened but remained significantly elevated throughout the delay period. Although the stimulus-specific representation in frontoparietal regions was weak and uneven, these regions closely tracked the higher order information of which stimulus category was relevant for behavior throughout the trial, suggesting an important role in controlling the prioritization of information in visual WM.

Short-range and long-range neuronal oscillatory coupling in multiple frequency bands during face perception

Neuronal oscillatory activity has been considered to play a key role in face processing through its functional effect on information flow and exchange in human brain. Specifically, most neuronal oscillatory activity is measured in different rhythm based on the electrophysiological signal at single channel level. Although, the neuronal oscillatory coupling between neuronal assembles is associated with the information flow and exchange between brain regions, few studies focus on this type of neuronal oscillatory activity in face processing. In this study, the neuronal oscillatory coupling was investigated based on electroencephalographic (EEG) data of 20 participants, which were recorded when the participants were in a face/non-face perceptual task. The phase lag index (PLI) was used to assess the neuronal oscillatory coupling between brain regions in typical frequency bands. Enhanced short-range coupling was observed in theta (4–8 Hz) and alpha (8–12 Hz) band over the frontal region, in gamma1 (30–49 Hz) band over the left posterior and occipito-temporal regions, and in gamma2 (51–75 Hz) over the right temporal region during face perception compared with non-face perception. Long-range coupling was increased in theta and gamma band over the right hemisphere during face perception. Moreover, increased long-range coupling was observed in alpha band over the left and right hemisphere respectively during face perception. The results suggested that frequency-specific neuronal oscillatory coupling within and between regions of frontal cortex and the ventral visual pathway played an important role in face perception, which might reflect underlying neural mechanism of face perception.

Functional organization of the ventral occipitotemporal regions for Chinese orthographic processing

Previous studies have found that the orthographic representation of alphabetic languages is hierarchically organized from the posterior to the anterior parts of the left ventral occipitotemporal area (vOT). More word-like stimuli, such as real words and pseudo-words, induced higher activation in the middle and the anterior parts of the left vOT compared to false fonts or consonant letter strings, while different types of orthographic stimuli induced equal activation in the posterior part of the left vOT. In addition, such hierarchically tuning effect was not found in the right vOT. However, it remains unclear whether such a hierarchical organization can be generalized to the processing of logographic languages, such as Chinese. In the present study, we examined Chinese orthographic processing in the vOT with a passive view task using functional magnetic resonance imaging (fMRI). Similar to alphabetic languages, the posterior part of the vOT responds equivalently to different types of Chinese stimuli, including real characters, pseudo-characters, false characters, and stroke combination, indicating its role in general visual processing. Unlike alphabetic languages, however, we found that false characters induced stronger responses compared to real characters and pseudo-characters in the middle part of the left vOT as well as the middle part of the right vOT. These findings demonstrate that the features of orthographic organization in bilateral vOTs may differ between Chinese and alphabetic languages, suggesting that the functional organization of the vOTs is modulated by different orthographic conventions.

Neural correlates of conceptual-level fear generalization in posttraumatic stress disorder.

Posttraumatic stress disorder (PTSD) may develop when mechanisms for making accurate distinctions about threat relevance have gone awry. Generalization across conceptually related objects has been hypothesized based on clinical observation in PTSD, but the neural mechanisms remain unexplored. Recent trauma-exposed military veterans (n = 46) were grouped into PTSD (n = 23) and non-PTSD (n = 23). Participants learned to generalize fear across conceptual categories (animals or tools) of semantically related items that were partially reinforced by shock during functional magnetic resonance imaging. Conditioned fear learning was quantified by shock expectancy and skin conductance response (SCR). Relative to veteran controls, PTSD subjects exhibited a stronger neural response associated with fear generalization to the reinforced object category in the striatum, anterior cingulate cortex, amygdala, occipitotemporal cortex, and insula (Z > 2.3; p < 0.05; whole-brain corrected). Based on SCR, both groups generalized the shock contingency to the reinforced conceptual category, but learning was not significantly different between groups. We found that PTSD was associated with an enhanced neural response in fronto-limbic, midline, and occipitotemporal regions to a learned representation of threat that is based on previously established conceptual knowledge of the relationship between basic-level exemplars within a semantic category. Behaviorally, veterans with PTSD were somewhat slower to differentiate threat and safety categories as compared with trauma-exposed veteran controls owing in part to an initial overgeneralized behavioral response to the safe category. These results have implications for understanding how fear spreads across semantically related concepts in PTSD.

A computerized version of the Short Form of the Face-Name Associative Memory Exam (FACEmemory\xae) for the early detection of Alzheimer\u2019s disease

BackgroundComputerized neuropsychological tests for early detection of Alzheimer’s disease (AD) have attracted increasing interest. Memory for faces and proper names is a complex task because its association is arbitrary. It implicates associative occipito-temporal cerebral regions, which are disrupted in AD. The short form of the Face-Name Associative Memory Exam (FNAME-12), developed to detect preclinical and prodromal AD, asks individuals to learn the names and occupations associated with 12 faces. The current work advances this field by using voice recognition and touchscreen response format. The purpose of this study is to create the first self-administered episodic memory test, FACEmemory®, by adapting the FNAME-12 for tablet use with voice recognition, touchscreen answers, and automatic scoring. The test was minimally supervised by a psychologist to avoid technological problems during execution and scored manually to assess the reliability of the automatic scoring. The aims of the present study were (1) to determine whether FACEmemory® is a sensitive tool for the detection of cognitive impairment, (2) to examine whether performances on FACEmemory® are correlated with those on the S-FNAME (paper-and-pencil version with 16 images), and (3) to determine whether performances on FACEmemory® are related to AD biomarkers in the cerebrospinal fluid (CSF) (Aβ42, p-tau, and Aβ42/p-tau ratio).MethodsFACEmemory® was completed by 154 cognitively healthy (CH) individuals and 122 subjects with mild cognitive impairment, of whom 61 were non-amnestic (naMCI) and 61 amnestic (aMCI). A subsample of 65 individuals completed the S-FNAME, and 65 subjects received lumbar punctures.ResultsPerformance on FACEmemory® was progressively worse from CH to the naMCI and aMCI groups. A cutoff of 31.5 in total FACEmemory® obtained 80.5% and 80.3% sensitivity and specificity values, respectively, for discriminating between CH and aMCI. Automatically corrected FACEmemory® scores were highly correlated with the manually corrected ones. FACEmemory® scores and AD CSF biomarker levels were significantly correlated as well, mainly in the aMCI group.ConclusionsFACEmemory® may be a promising memory prescreening tool for detecting subtle memory deficits related to AD. Our findings suggest FACEmemory® performance provides a useful gradation of impairment from normal aging to aMCI, and it is related to CSF AD biomarkers.

Identity-specific neural responses to three categories of face familiarity (own, friend, stranger) using fast periodic visual stimulation

Previous studies have focused on the modulatory effects of face familiarity on different components of an event-related potential (ERP), but there is controversy in the literature regarding the precise component that reflects the process of identity recognition. This may be partly explained by limits to this waveform analysis approach, as waveforms elicited by the presentation of a face are likely to reflect a variety of different cognitive processes that overlap in time. Using fast periodic visual stimulation and EEG (FPVS-EEG), we directly measured the electrophysiological response reflecting identity-specific recognition after isolating it from responses attributable to low-level visual processing and face-selective processes that are not identity-specific. The observed response therefore provides a robust and objective measure of the recognition of a personally familiar face generated bilaterally in the occipito-temporal region. We tested the magnitude of this identity-specific response to three categories of familiarity: the own-face (high familiarity), a friend's face (moderate familiarity), and a stranger's face (no familiarity). We found the largest response to the participant's own-face, followed by an intermediate response to a highly personally familiar face, and the smallest response to an unfamiliar face. An additional response was observed over the posterior cortical midline for familiar faces only, consistent with theories that familiar identity recognition also triggers post-perceptual semantic processing.

Co-stimulation-removed audiovisual semantic integration and modulation of attention: An event-related potential study

The integration of multisensory objects containing semantic information involves processing of both low-level co-stimulation and high-order semantic integration. To investigate audiovisual semantic integration, we utilized bimodal stimuli (AV, simultaneous presentation of an auditory sound and a visual picture; An, simultaneous presentation of an auditory sound and a visual noise; Vn, simultaneous presentation of a visual picture and an auditory noise; Fn, simultaneous presentation of an auditory noise and a visual noise) to remove the effect of co-stimulation integration and extract data regarding high-order semantic integration. Electroencephalography with a high temporal resolution was used to examine the neural mechanisms associated with co-stimulation-removed audiovisual semantic integration in attended and unattended conditions. By comparing the (AV + Fn) and (An+Vn), we identified three effects related to co-stimulation-removed audiovisual semantic integration. In the attended condition, two semantic integration effects over bilateral occipito-temporal regions at 220–240 ms and over frontal region at 560–600 ms were observed. In the unattended condition, only one semantic integration effect over centro-frontal region at 340–360 ms was observed. These effects reflected the semantic integration processes of pictures and sounds after removing the co-stimulation caused by spatiotemporal consistency. Moreover, the discrepancy in these effects in temporal and spatial distribution implied distinct neural mechanisms underlying attended and unattended semantic integration. In the attended condition, the audiovisual semantic information was initially integrated based on the semantic congruency (220–240 ms) and then reanalyzed according to the current task (560–600 ms), which was a goal-driven process and influenced by top-down attention. Contrastingly, in the unattended condition, no attention resources were allocated and the semantic integration (340–360 ms) was an unconscious automatic process.