Gaze direction affects face perception in humans

SummaryHumans show a remarkable ability to discriminate others' gaze direction, even though a given direction can be conveyed by many physically dissimilar configurations of different eye positions and head views. For example, eye contact can be signaled by a rightward glance in a left-turned head or by direct gaze in a front-facing head. Such acute gaze discrimination implies considerable perceptual invariance. Previous human research found that superior temporal sulcus (STS) responds preferentially to gaze shifts [1], but the underlying representation that supports such general responsiveness remains poorly understood. Using multivariate pattern analysis (MVPA) of human functional magnetic resonance imaging (fMRI) data, we tested whether STS contains a higher-order, head view-invariant code for gaze direction. The results revealed a finely graded gaze direction code in right anterior STS that was invariant to head view and physical image features. Further analyses revealed similar gaze effects in left anterior STS and precuneus. Our results suggest that anterior STS codes the direction of another's attention regardless of how this information is conveyed and demonstrate how high-level face areas carry out fine-grained, perceptually relevant discrimination through invariance to other face features.

We present a novel group-wise registration method for cortical correspondence for local cortical thickness analysis in human and non-human primate neuroimaging studies. The proposed method is based on our earlier template based registration that estimates a continuous, smooth deformation field via sulcal curve-constrained registration employing spherical harmonic decomposition of the deformation field. This pairwise registration though results in a well-known template selection bias, which we aim to overcome here via a group-wise approach. We propose the use of an unbiased ensemble entropy minimization following the use of the pairwise registration as an initialization. An individual deformation field is then iteratively updated onto the unbiased average. For the optimization, we use metrics specific for cortical correspondence though all of these are straightforwardly extendable to the generic setting: The first focused on optimizing the correspondence of automatically extracted sulcal landmarks and the second on that of sulcal depth property maps. We further propose a robust entropy metric and a hierarchical optimization by employing spherical harmonic basis orthogonality. We also provide the detailed methodological description of both our earlier work and the proposed method with a set of experiments on a population of human and non-human primate subjects. In the experiment, we have shown that our method achieves superior results on consistency through quantitative and visual comparisons as compared to the existing methods.

Previous work using single-cell recordings in monkeys and neuro-imaging studies in humans has shown that perceiving an object or imaging the action associated with the object recruits the same brain regions in the ventral premotor cortex as performing an action with the object. We used functional magnetic resonance imaging (fMRI) for examining whether similar brain regions are also activated while maintaining information about manipulable objects in working memory. Holding information about manipulable objects in working memory activated the left ventral premotor cortex and the left inferior frontal gyrus (Broca's area). Conversely, non-manipulable objects to be held in working memory co-activated Broca's area and the left angular gyrus. When contrasted directly, manipulable relative to non-manipulable objects activated the left ventral premotor cortex and the anterior intraparietal sulcus, a circuitry that is assumed to mediate the transformation of movement-relevant object properties into hand actions. These results indicate that visual working memory for manipulable objects is based on motor programmes associated with their use. Similar to speech motor programmes in verbal memory tasks, hand motor programmes may allow the maintenance of objects in working memory over short intervals.

The human visual system appears to process the identity of faces separately from their emotional expression, whereas the human visual system does not appear to process emotional expression separately from identity. All current explanations of this visual processing asymmetry implicitly assume that it arises because of the organization of a specialized human face perception system. A second possibility is that this finding reflects general principles of perceptual processing. Studying animals that are unlikely to have evolved a specialized face perception system may shed fresh light on this issue. We report two experiments that investigated the interaction of identity and emotional expression in pigeons' perception of human faces. Experiment 1 found that pigeons perceive the similarity among faces sharing identity and emotion, and that these two dimensions are integral according to a spatial model of generalization. Experiment 2 found that pigeons' discrimination of emotion was reliably affected by irrelevant variations in identity, whereas pigeons' discrimination of identity was not reliably affected by irrelevant variations in emotion. Thus, the asymmetry previously reported in human studies was reproduced in our pigeon study. These results challenge the view that a specialized human face perception system must underlie this effect.

ABSTRACTAccording to current textbook knowledge, the primary somatosensory cortex (SI) supports unilateral tactile representations, whereas structures beyond SI, in particular the secondary somatosensory cortex (SII), support bilateral tactile representations. However, dexterous and well-coordinated bimanual motor tasks require early integration of bilateral tactile information. Sequential processing, first of unilateral and subsequently of bilateral sensory information, might not be sufficient to accomplish these tasks. This view of sequential processing in the somatosensory system might therefore be questioned, at least for demanding bimanual tasks. Evidence from the last 15 years is forcing a revision of this textbook notion. Studies in animals and humans indicate that SI is more than a simple relay for unilateral sensory information and, together with SII, contributes to the integration of somatosensory inputs from both sides of the body. Here, we review a series of recent works from our own and other laboratories in favour of interactions between tactile stimuli on the two sides of the body at early stages of processing. We focus on tactile processing, although a similar logic may also apply to other aspects of somatosensation. We begin by describing the basic anatomy and physiology of interhemispheric transfer, drawing on neurophysiological studies in animals and behavioural studies in humans that showed tactile interactions between body sides, both in healthy and in brain-damaged individuals. Then we describe the neural substrates of bilateral interactions in somatosensation as revealed by neurophysiological work in animals and neuroimaging studies in humans (i.e., functional magnetic resonance imaging, magnetoencephalography, and transcranial magnetic stimulation). Finally, we conclude with considerations on the dilemma of how efficiently integrating bilateral sensory information at early processing stages can coexist with more lateralized representations of somatosensory input, in the context of motor control.

Humans and Macaques Employ Similar Face-Processing Strategies

Noise alters beta-band activity in superior temporal cortex during audiovisual speech processing

Event-related potentials (ERPs) evoked by key stimuli informing a subject about the forthcoming recognition of the global or local level of a hierarchical test figure were analyzed in 7-year-old children with different levels of maturity of the regulatory brain systems. Differences in both the initial ERP components P1, N1, and P2 (which reflect the analysis of the sensory characteristics and significance of a key stimulus) and the late components N3, Pc, and Nc (which reflect the preparation for the recognition of a subsequent test figure) were found. It was shown that, in children with frontal-thalamic regulatory system immaturity (FTRSI), the amplitude of the ERP component N1 is decreased in the caudal areas. In children with an immature bottom-up activation system, a decrease in the amplitude of initial ERP components in the caudal areas was observed in a broader time interval in components P1, N1, and P2. As compared to the control groups of children, in children with immature frontal-thalamic structures, components N3, Pc, and Nc were different in both the caudal and precentral areas. In children with immature lower brainstem activation structures, the late ERP components were different, predominantly, in the parietal and temporo-parieto-occipital areas. Comparison of ERPs in response to global and local key stimuli in children of the control group demonstrated a clear-cut temporal and topographical organization in the period of preparation for subsequent recognition of a prescribed level of the test stimulus: the earlier preparation stages were associated with component N3 in the parietal and temporo-parieto-occipital areas, whereas later stages were associated with Pc changes in the frontal areas. In children with FTRSI, changes in the late components in the caudal areas were poorly expressed and their topographical organization (characteristic of the control group) was absent; the involvement of the frontal areas in the late stages of the key stimulus analysis was restricted. These findings may give grounds to suggest the significance of the frontal-thalamic system in the organization of the response to an expected stimulus. In children with immature lower brainstem activation structures, the type of the key stimulus was reflected in the late ERP components in a diffuse way.

Recent human neuroimaging studies indicate that by using fMRI we can “see” what people are thinking. In animals, we can more accurately see what the animal has in mind by using invasive methods that cannot be used in human subjects. Here I introduce experimental studies where single neuronal activities were examined in the monkey prefrontal cortex in relation to working memory and reward expectancy. We found that by monitoring the neuronal activity while the animal is waiting for the next event, we can see what the monkey is retaining or expecting in mind. Human neuroimaging studies have well documented “default mode of brain activity”, which is higher activity during the resting state than during cognitively demanding task, and is concerned with internal thought processes, in the medial prefrontal and medial parietal areas. In our PET study, we also found higher activity during rest in these medial cortical areas of the monkey. The result suggests that there are primitive-level internal thought processes in the monkey.

To understand how a model of Alzheimer disease pathophysiology based on β-amyloidosis and neurodegeneration predicts the regional anatomic expansion of hypometabolism and atrophy in persons with mild cognitive impairment (MCI). To define the role of β-amyloidosis and neurodegeneration in the subsequent progression of topographic cortical structural and metabolic changes in MCI. Longitudinal, observational study with serial brain imaging conducted from March 28, 2006, to January 6, 2015, using a population-based cohort. A total of 96 participants with MCI (all aged >70 years) with serial imaging biomarkers from the Mayo Clinic Study of Aging or Mayo Alzheimer's Disease Research Center were included. Participants were characterized initially as having elevated or not elevated brain β-amyloidosis (A+ or A-) based on 11C-Pittsburgh compound B positron emission tomography. They were further characterized initially by the presence or absence of neurodegeneration (N+ or N-), where the presence of neurodegeneration was defined by abnormally low hippocampal volume or hypometabolism in an Alzheimer disease-like pattern on 18fluorodeoxyglucose (FDG)-positron emission tomography. Regional FDG standardized uptake value ratio (SUVR) and gray matter volumes in medial temporal, lateral temporal, lateral parietal, and medial parietal regions. In the primary regions of interest (ROI), the A+N+ group (n = 45) had lower FDG SUVR at baseline compared with the A+N- group (n = 17) (all 4 ROIs; P < .001). The A+N+ group also had lower FDG SUVR at baseline (all 4 ROIs; P < .01) compared with the A-N- group (n = 12). The A+N+ group had lower medial temporal gray matter volume at baseline (P < .001) compared with either the A+N- group or A-N- group. The A+N+ group showed large longitudinal declines in FDG SUVR (P < .05 for medial temporal, lateral temporal, and medial parietal regions) and gray matter volumes (P < .05 for medial temporal and lateral temporal regions) compared with the A-N+ group (n = 22). The A+N+ group also showed large longitudinal declines compared with the A-N- group on FDG SUVR (P < .05 for medial temporal and lateral parietal regions) and gray matter volumes (all 4 ROIs; P < .05) compared with the A+N- group. The A-N+ group did not show declines in FDG SUVR or gray matter volume compared with the A+N- or A-N- groups. Persons with MCI who were A+N+ demonstrated volumetric and metabolic worsening in temporal and parietal association areas, consistent with the expectation that the MCI stage in the Alzheimer pathway heralds incipient isocortical involvement. The A-N+ group, those with suspected non-Alzheimer pathophysiology, lacked a distinctive longitudinal volumetric or metabolic profile.

Event Abstract Back to Event Development of audiovisual integration of print and speech in normal and poor readers: An ERP and fMRI study Silvia Brem1, 2*, Ulla Richardson1, Silvia Bach1, 2, Christoph Hofstetter2, Ernst Martin3, 4 and Daniel Brandeis2, 4, 5 1 University of Jyväskylä, Agora Center, Finland 2 University of Zurich, Department of Child and Adolescent Psychiatry, Switzerland 3 University Childrens Hospital Zurich, MR-Center, Switzerland 4 University of Zurich, Center for Integrative Human Physiology, Switzerland 5 Central Institute of Mental Health, Department of Child and Adolescent Psychiatry, Germany The integration of multisensory information from speech and print is highly automatized in good readers but remains deficient in poor readers (Blau et al. 2009). Recent studies consistently point to the crucial involvement of the superior temporal sulcus (STS) in integration (van Atteveldt et al. 2004) and conceptual matching (Hocking and Price 2008) of incoming audiovisual information starting around 380ms (Raij et al. 2000) after presentation. In this study we aimed to track emergence and development of audiovisual integration from kindergarten to adulthood in normal and poor readers with functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs). Non-reading kindergartners (n=14, 5.7-7.1y), normal (n=31, 7.8-9.2y) and poor reading (n=15, 7.8-8.9y) 2nd graders as well as normal reading adults (n=15, 21.9-34.5y) were examined with fMRI and ERPs. Conceptual matching effects determined by the statistical difference between incongruous and congruous audiovisual conditions are reported for each age group and for the differences between groups. While kindergarten children did not show conceptual matching effects, normal reading 2nd graders and adults activated inferior frontal and superior temporal brain regions more to incongruous than congruous items. The inferior frontal activation of the 2nd graders was furthermore correlated with reading performance. ERPs pointed to a mismatch effect in the form of a pronounced centro-parietal negativity starting at around 380ms in adults, which was delayed in normal reading 2nd graders. In contrast to adults, 2nd graders showed an additional earlier condition difference around 140-220ms. In summary our results show that incongruous presentation of speech and print evokes a conceptual mismatch effect in fMRI and ERPs as soon as children’s basic reading skills allow matching written to spoken information. The modulation of the matching effect by children’s reading skills points to deficient integration of audiovisual information in poor readers. Conference: EARLI SIG22 - Neuroscience and Education, Zurich, Switzerland, 3 Jun - 5 Jun, 2010. Presentation Type: Poster Presentation Topic: Language and reading Citation: Brem S, Richardson U, Bach S, Hofstetter C, Martin E and Brandeis D (2010). Development of audiovisual integration of print and speech in normal and poor readers: An ERP and fMRI study. Front. Neurosci. Conference Abstract: EARLI SIG22 - Neuroscience and Education. doi: 10.3389/conf.fnins.2010.11.00010 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 May 2010; Published Online: 28 May 2010. * Correspondence: Silvia Brem, University of Jyväskylä, Agora Center, Jyväskylä, Finland, sbrem@kjpd.uzh.ch Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Silvia Brem Ulla Richardson Silvia Bach Christoph Hofstetter Ernst Martin Daniel Brandeis Google Silvia Brem Ulla Richardson Silvia Bach Christoph Hofstetter Ernst Martin Daniel Brandeis Google Scholar Silvia Brem Ulla Richardson Silvia Bach Christoph Hofstetter Ernst Martin Daniel Brandeis PubMed Silvia Brem Ulla Richardson Silvia Bach Christoph Hofstetter Ernst Martin Daniel Brandeis Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Neuroimaging studies in humans have implicated both dysfunction of the medial temporal lobe (MTL) and the dopamine system in psychosis, but the relationship between them is unclear. We addressed this issue by measuring MTL activation and striatal dopaminergic function in individuals with an At Risk Mental State (ARMS) for psychosis, using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), respectively. Thirty-four subjects (20 ARMS and 14 Controls), matched for age, gender, digit span performance, and premorbid IQ, were scanned using fMRI, while performing a verbal encoding and recognition task, and using 18F-DOPA PET. All participants were naïve to antipsychotic medication. ARMS subjects showed reduced MTL activation when encoding words and made more false alarm responses for Novel words than controls. The relationship between striatal dopamine function and MTL activation during both verbal encoding and verbal recognition was significantly different in ARMS subjects compared with controls. An altered relationship between MTL function and dopamine storage/synthesis capacity exists in the ARMS and may be related to psychosis vulnerability.

Neuroimaging and neurogenetics of epilepsy in humans

Neuroimaging studies in humans have localized brain functions to specific brain regions, but a recent shift toward distributed network-based models of brain function promises deeper insights into the network processes that generate brain functionality. Resting-state functional connectivity provides a rich mapping of the brain’s network architecture, linking with both underlying structure and task-evoked responses across the whole brain. In this study, we utilized a model based on propagation of task-evoked activations over resting-state functional connectivity networks to identify cortical contributions to localized functional brain activations associated with binocular convergent eye movements. Binocular vision is crucial for daily routine activities, with its impairment leading to significant challenges in daily life. The distributed network-level mechanisms of binocular convergent eye movements remain unknown. Results showed that mapping activity flow over brain connections accurately generated actual brain activations associated with convergent eye movements, which were distinct from those observed during control tasks. The visual and dorsal attention networks dominated the propagation of activations through resting-state connections during convergent eye movements. Submodel analyses further revealed that restricting activity flow to individual networks, such as the visual or dorsal attention systems alone, substantially reduced model accuracy, underscoring the necessity of distributed, whole-brain contributions. In conclusion, highly distributed network pathways are involved in convergent eye movements, with some pathways contributing much more than others, providing important implications for future clinical models of binocular dysfunction.

91 - Stress and Anxiety Disorders