Biology subjects

Pitcher, D.

Publications and source records attributed to Pitcher, D..

13 recordsLinked to original sources

bioRxiv2026

Disrupting the Right Inferior Frontal Gyrus Increases Social Brain Activity During Emotion Recognition

Neuroimaging studies have identified a specialised social brain network that supports emotion recognition and social cognition. This network performs a range of functions that include facial expression recognition and inferring the mental states of others. Studies of neuropsychological patients report that damage to the right inferior frontal gyrus (IFG), the top-down control area in this network, impairs facial expression recognition. To investigate how transient disruption of the right IFG affects the wider social brain we combined transcranial magnetic stimulation (TMS) with functional magnetic resonance imaging (fMRI). Participants (n=20) were scanned across two sessions while performing a delayed match-to-sample emotion recognition task in which happy or fearful expressions were preceded by a congruent or incongruent word cue. Prior to each scan, thetaburst TMS was delivered over the right IFG or over the vertex control site (session order was balanced across participants). A group whole-brain analysis revealed that TMS to the IFG increased neural activity in multiple regions of the social brain network. These included the bilateral temporal pole, precuneus and medial prefrontal cortex (mPFC). This pattern of results shows that the disruption of top-down control mechanisms localised in the IFG alters the neural processing in remote nodes of the social brain network. Our findings are discussed within the wider context of how we recognise and understand the emotions of other people.

neuroscience↗

bioRxiv2025

Ensemble encoding of facial expressions is greater for static faces than dynamic faces

Understanding the behaviour and emotions of other people is predicated on accurately decoding nonverbal facial cues. In the current study, we investigated whether the ensemble encoding of these facial cues is processed differently between moving and static faces. Across two experiments, participants performed a delayed-match-to-sample expression recognition task using dynamic and static stimuli. Ensemble size was manipulated by increasing the number of faces in the target array. In Experiment 1, we presented one, two, and four target faces. In Experiment 2, we presented one, four, and eight target faces. Results demonstrated that while recognition accuracy for dynamic and static faces was comparable when one target face was presented, task accuracy diverged as the ensemble size increased. Specifically, increasing the number of faces in the target array failed to improve task performance for the dynamic expression stimuli. In addition, the results of Experiment 2 demonstrated that when eight faces were presented in the dynamic condition, performance was impaired for all expressions (disgust, fear, and happy) as well as in the non-emotional air-puff condition. This suggests motion in general disrupted the participants ability to extract an accurate summary statistic as the ensemble size was increased.

neuroscience↗

bioRxiv2025

Distinct Mechanisms of Surround Modulation for Dynamic Natural Scenes in Motion- and Scene-Selective Cortex

Surround modulation refers to changes in neural responses to a central stimulus induced by its surrounding context, which can manifest as either suppression or facilitation. Although this phenomenon is well established for simple stimuli, its underlying neural mechanism during natural scene perception remains unclear. Using fMRI, we examined how motion congruence and categorical similarity between central and surrounding scenes shape surround modulation across the visual hierarchy. Central and surrounding scenes systematically varied in categorical similarity (identical exemplar, different exemplar of the same basic-level category, different basic-level category, or different superordinate category) and in motion direction (same or opposite direction). Neural responses were measured in primary visual cortex (V1), motion-selective cortex (hMT+), and scene-selective occipital and parahippocampal place areas (OPA and PPA). hMT+ showed robust motion-dependent surround suppression, which was stronger for same-direction motion. In contrast, V1 showed surround facilitation across all conditions, which was reduced when center and surround were identical and moved in the same direction, consistent with sensitivity to physical similarity. OPA and PPA primarily exhibited facilitation. Multivariate decoding between center-only and center-surround conditions complemented these findings, revealing motion-dependent surround modulation in hMT+, and category-dependent surround modulation in OPA and PPA. Across the visual hierarchy, surrounding scene context thus systematically attenuates redundant input or enhances informative differences: from low-level facilitation in V1 to motion-dependent suppression in hMT+ and category-dependent modulation in scene-selective regions.

neuroscience↗

bioRxiv2025

How do visual and conceptual factors predict the composition of typical scene drawings?

Imagine you are asked to draw a typical bedroom, what would you put on paper? Your choice of objects is likely to depend on visual occurrence statistics (i.e., the objects present in previously encountered bedrooms) and semantic relations between objects and scenes (i.e., the semantic relationship between the bedroom and its constituent objects). To investigate how these two factors contribute to the composition of typical scene drawings, we analyzed 1,192 drawings of six indoor scene categories, obtained from 303 participants. For each object featured in the drawings, we estimated its visual occurrence frequency from the ADE20K dataset of annotated scene images, and its semantic relatedness to the scene concept from a word2vec language processing model. Across all scenes of a given category, generalized linear models revealed that visual and conceptual factors both predicted the likelihood of an object featuring in the scene drawings, with a combined model outperforming both single-factor models. We further computed the visual and semantic specificity of objects for a given scene, that is, how diagnostic an object is for the scene. Object specificity offered only weak predictive power when predicting the selection of objects, yet even infrequently drawn objects remained diagnostic of their scenes. Taken together, we show that visual and conceptual factors jointly shape the composition of typical scene drawings. By releasing a large dataset of typical scene drawings alongside this work, we further provide a starting point for future studies exploring other critical properties of human drawings.

neuroscience↗

bioRxiv2025

Investigating diurnal effects and joint nest defense behavior in Herring Gulls

Nest defense in birds is vital for the protection of their young, but can prove energetically costly. Birds often show plasticity in nest defense depending on factors such as threat level, mate presence, nest stage, and body condition. Such factors can vary over temporal extents ranging from a diel cycle to a breeding season or an individuals lifetime. Understanding diurnal variation in nest defense intensity can be particularly useful when studying a breeding population to help investigators minimize nest disturbance, yet few studies have explored diurnal variation in nest defense intensity. Here we investigated how nest defense by Herring Gulls (Larus smithsonianus) varies with time of day. We simulated predatory threat at 26 Herring Gull nests during four different times of day: "Early Morning" (0530-0600), "Late Morning" (1000-1030), "Afternoon" (1400-1430), and "Evening" (1900-1930). Based on previous findings of diurnal activity patterns in a Herring Gull, we predicted that nest defense intensity--measured as aggressiveness of response and latency to calm--would be greater during the early morning and late evening than at other times. Contrary to our prediction, we found that the time of day did not affect nest defense intensity in Herring Gulls. However, independent of time of day, we found that when both mates were present at the nest, aggression scores were elevated. Our results suggest that joint nest defense in Herring Gulls permits greater aggressiveness towards predators, perhaps due to division of labor or lowered risk of complete nest failure if one parent is injured or killed. Further, our results indicate that researchers can minimize nest disturbance and accompanying stress by limiting research activities at Herring Gull nests when both parents are present.

animal behavior and cognition↗

bioRxiv2023

Visual to default network pathways: A double dissociation between semantic and spatial cognition

Processing pathways between sensory and default mode network (DMN) regions support recognition, navigation, and memory but their organisation is not well understood. We show that functional subdivisions of visual cortex and DMN sit at opposing ends of parallel streams of information processing that support visually-mediated semantic and spatial cognition, providing convergent evidence from univariate and multivariate task responses, intrinsic functional and structural connectivity. Participants learned virtual environments consisting of buildings populated with objects, drawn from either a single semantic category or multiple categories. Later, they made semantic and spatial context decisions about these objects and buildings during functional magnetic resonance imaging. A lateral ventral occipital to frontotemporal DMN pathway was primarily engaged by semantic judgements, while a medial visual to medial temporal DMN pathway supported spatial context judgements. These pathways had distinctive locations in functional connectivity space: the semantic pathway was both further from unimodal systems and more balanced between visual and auditory-motor regions compared with the spatial pathway. When semantic and spatial context information could be integrated (in buildings containing objects from a single category), regions at the intersection of these pathways responded, suggesting that parallel processing streams interact at multiple levels of the cortical hierarchy to produce coherent memory-guided cognition.

neuroscience↗

bioRxiv2023

Identifying the cortical face network with dynamic face stimuli: A large group fMRI study

Functional magnetic resonance imaging (fMRI) studies have identified a network of face-selective regions distributed across the human brain. In the present study, we analyzed data from a large group of gender-balanced participants to investigate how reliably these face-selective regions could be identified across both cerebral hemispheres. Participants (N=52) were scanned with fMRI while viewing short videos of faces, bodies, and objects. Results revealed that five face-selective regions: the fusiform face area (FFA), posterior superior temporal sulcus (pSTS), anterior superior temporal sulcus (aSTS), inferior frontal gyrus (IFG) and the amygdala were all larger in the right than in the left hemisphere. The occipital face area (OFA) was larger in the right hemisphere as well, but the difference between the hemispheres was not significant. The neural response to moving faces was also greater in face-selective regions in the right than in the left hemisphere. An additional analysis revealed that the pSTS and IFG were significantly larger in the right hemisphere compared to other face-selective regions. This pattern of results demonstrates that moving faces are preferentially processed in the right hemisphere and that the pSTS and IFG appear to be the strongest drivers of this laterality. An analysis of gender revealed that face-selective regions were typically larger in females (N=26) than males (N=26), but this gender difference was not statistically significant.

neuroscience↗

bioRxiv2023

TMS disruption of the lateral prefrontal cortex increases neural activity in the default mode network when naming facial expressions

Recognizing facial expressions is dependent on multiple brain networks specialized for different cognitive functions. In the current study participants (N=20) were scanned using functional magnetic resonance imaging (fMRI) while they performed a covert facial expression naming task. Immediately prior to scanning thetaburst transcranial magnetic stimulation (TMS) was delivered over the right lateral prefrontal cortex (PFC), or the vertex control site. A group whole-brain analysis revealed that TMS induced opposite effects in the neural responses across different brain networks. Stimulation of the right PFC (compared to stimulation of the vertex) decreased neural activity in the left lateral PFC but increased neural activity in three nodes of the default mode network (DMN): the right superior frontal gyrus (SFG), right angular gyrus and the bilateral middle cingulate gyrus. A region of interest (ROI) analysis showed that TMS delivered over the right PFC reduced neural activity across all functionally localised face areas (including in the PFC) compared to TMS delivered over the vertex. These results causally demonstrate that visually recognizing facial expressions is dependent on the dynamic interaction of the face processing network and the DMN. Our study also demonstrates the utility of combined TMS / fMRI studies for revealing the dynamic interactions between different functional brain networks.

neuroscience↗

bioRxiv2022

Moving and static faces, bodies, objects and scenes are differentially represented across the three visual pathways

Models of human cortex propose the existence of neuroanatomical pathways specialised for different behavioural functions. These pathways include a ventral pathway for object recognition, a dorsal pathway for performing visually guided physical actions and a recently proposed third pathway for social perception. In the current study we tested the hypothesis that different categories of moving stimuli are differentially processed across the dorsal and third pathways according to their behavioural implications. Human participants (N=30) were scanned with functional magnetic resonance imaging (fMRI) while viewing moving and static stimuli from five categories (faces, bodies, scenes, objects, and scrambled objects). Whole brain group analyses showed that moving bodies and moving objects increased neural responses in bilateral V5/MT+ and intraparietal sulcus (IPS), parts of the dorsal pathway. In addition, moving faces and moving bodies increased neural responses in bilateral V5/MT+ and the right posterior superior temporal sulcus (rpSTS), parts of the third pathway. This pattern of results was also supported by a separate region of interest (ROI) analysis showing that moving stimuli produced more robust neural responses for all visual object categories, particularly in lateral and dorsal brain areas. Our results suggest that dynamic naturalistic stimuli from different categories are routed along specific visual pathways that process their unique behavioural implications.

neuroscience↗

bioRxiv2022

Measuring the response to visually presented faces in the human lateral prefrontal cortex

Neuroimaging studies have identified multiple face-selective areas. In the current study we compared the functional response of the face area in the lateral prefrontal cortex to that of other face-selective areas. In Experiment 1 participants (N=32) were scanned viewing videos containing faces, bodies, scenes, objects, and scrambled objects. We identified a face-selective area in the right inferior frontal gyrus (rIFG). In Experiment 2 participants (N=24) viewed the videos or static images. Results showed that the rIFG, posterior superior temporal sulcus (pSTS) and occipital face area (OFA) exhibited a greater response to moving than static faces. In Experiment 3 participants (N=18) viewed face videos presented in the contralateral and ipsilateral visual fields. Results showed that the face areas in the IFG and pSTS responded equally to faces in both visual fields, while the OFA and fusiform face area (FFA) showed a contralateral bias. These experiments suggest two conclusions; firstly, in all three experiments the face area in the IFG was not as reliably identified as face areas in the occipitotemporal cortex. Secondly, the similarity of the response patterns in the IFG and pSTS face areas suggests that the areas are functionally connected, a conclusion consistent with neuroanatomical and functional connectivity evidence.

neuroscience↗

bioRxiv2020

TMS of lateral occipital cortex reduces BOLD responses across category-selective areas in ventral temporal cortex

Human visual cortex contains three scene-selective regions in the lateral, medial and ventral cortex, termed the occipital place area (OPA), medial place area (MPA) and parahippocampal place area (PPA). Using functional magnetic resonance imaging (fMRI), all three regions respond more strongly when viewing visual scenes compared with isolated objects or faces. To determine how these regions are functionally and causally connected, we applied transcranial magnetic stimulation to OPA and measured fMRI responses before and after stimulation, using a theta-burst paradigm (TBS). To test for stimulus category-selectivity, we presented a range of visual categories (scenes, buildings, objects, faces). To test for specificity of any effects to TBS of OPA we employed two control conditions: Sham, with no TBS stimulation, and an active TBS-control with TBS to a proximal face-selective cortical region (occipital face area, or OFA). We predicted that TBS to OPA (but not OFA) would lead to decreased responses to scenes and buildings (but not other categories) in other scene-selective cortical regions. Across both ROI and whole-volume analyses, we observed decreased responses to scenes in PPA as a result of TBS. However, these effects were neither category specific, with decreased responses to all stimulus categories, nor limited to scene-selective regions, with decreases also observed in face-selective fusiform face area (FFA). Furthermore, similar effects were observed with TBS to OFA, thus effects were not specific to the stimulation site in the lateral occipital cortex. Whilst these data are suggestive of a causal, but non-specific relationship between lateral occipital and ventral temporal cortex, we discuss several factors that could have underpinned this result, such as the differences between TBS and online TMS, the role of anatomical distance between stimulated regions and how TMS effects are operationalised. Furthermore, our findings highlight the importance of active control conditions in brain stimulation experiments to accurately assess functional and causal connectivity between specific brain regions.

neuroscience↗

bioRxiv2019

Dual-site TMS demonstrates causal functional connectivity between the left and right posterior temporal sulci during facial expression recognition.

BackgroundNeuroimaging studies suggest that facial expression recognition is processed in the bilateral posterior superior temporal sulcus (pSTS). Our recent repetitive transcranial magnetic stimulation (rTMS) study demonstrates that the bilateral pSTS is causally involved in expression recognition, although involvement of the right pSTS is greater than involvement of the left pSTS.\n\nObjective/HypothesisIn this study, we used a dual-site TMS to investigate whether the left pSTS is functionally connected to the right pSTS during expression recognition. We predicted that if this connection exists, simultaneous TMS disruption of the bilateral pSTS would impair expression recognition to a greater extent than unilateral stimulation of the right pSTS.\n\nMethodsParticipants attended two TMS sessions. In Session 1, participants performed an expression recognition task while rTMS was delivered to the face-sensitive right pSTS (experimental site), object-sensitive right lateral occipital complex (control site) or no rTMS was delivered (behavioural control). In Session 2, the same experimental design was used except that continuous theta-burst stimulation (cTBS) was delivered to the left pSTS immediately before behavioural testing. Session order was counter-balanced across participants.\n\nResultsIn Session 1, rTMS to the rpSTS impaired performance accuracy compared to the control conditions. Crucially in Session 2, the size of this impairment effect doubled after cTBS was delivered to the left pSTS.\n\nConclusionsOur results provide evidence for a causal functional connection between the left and right pSTS during expression recognition. In addition, this study further demonstrates the utility of the dual-site TMS for investigating causal functional links between brain regions.

neuroscience↗

bioRxiv2019

Thetaburst TMS to the posterior superior temporal sulcus decreases resting-state fMRI connectivity across the face processing network

Humans process faces using a network of face-selective regions distributed across the brain. Neuropsychological patient studies demonstrate that focal damage to nodes in this network can impair face recognition, but such patients are rare. We approximated the effects of damage to the face network in neurologically normal human participants using thetaburst transcranial magnetic stimulation (TBS). Multi-echo functional magnetic resonance imaging (fMRI) resting-state data were collected pre- and post-TBS delivery over the face-selective right superior temporal sulcus (rpSTS), or a control site in the right motor cortex. Results showed that TBS delivered over the rpSTS reduced resting-state connectivity across the extended face-processing network. This connectivity reduction was observed not only between the rpSTS and other face-selective areas, but also between non-stimulated face-selective areas across the ventral, medial and lateral brain surfaces (e.g. between the right amygdala and bilateral fusiform face areas and occipital face areas). TBS delivered over the motor cortex did not produce significant changes in resting-state connectivity across the face-processing network. These results demonstrate that, even without task-induced fMRI signal changes, disrupting a single node in a brain network can decrease the functional connectivity between nodes in that network that have not been directly stimulated. Author SummaryHuman behavior is dependent on brain networks that perform different cognitive functions. We combined thetaburst transcranial magnetic stimulation (TBS) with resting-state fMRI to study the face processing network. Disruption of the face-selective right posterior superior temporal sulcus (rpSTS) reduced fMRI connectivity across the face network. This impairment in connectivity was observed not only between the rpSTS and other face-selective areas, but also between non-stimulated face-selective areas on the ventral and medial brain surfaces (e.g. between the right amygdala and bilateral fusiform face areas and occipital face areas). Thus, combined TBS/fMRI can be used to approximate and measure the effects of focal brain damage on brain networks, and suggests such an approach may be useful for mapping intrinsic network organization. Technical TermsO_ST_ABSTBS vs TMSC_ST_ABSTranscranial magnetic stimulation (TMS) is a method that induces current in neural tissue by using a rapidly changing magnetic field. The pattern of magnetic field changes can vary. Thetaburst TMS (TBS) is a type of TMS where the same stimulation pattern fluctuates at around a 5Hz cycle. Multi-echo fMRIDuring typical fMRI, protons are excited and there is a delay, the echo time, before data are collected. That delay is typically designed to result in a high contrast for blood oxygenation differences. In multi-echo fMRI, data are collected at several echo times each time protons are excited. This results in data that have different levels of contrast for blood oxygenation differences. This added information can be used to empirically decrease noise. Face networkA group of brain regions that show significant activity changes in response to visual face stimuli. While these regions have been defined using univariate analyses with task-based fMRI, they often significantly correlate with each other at rest. In this manuscript, the following regions were a priori defined as part of the face network: posterior superior temporal sulcus (pSTS), amygdala, fusiform face area (FFA), and occipital face area (OFA). Matrix based analysis (MBA)A recent approach that uses a Bayesian multilevel modeling framework to identify pairs of ROIs where a decrease in correlation magnitude was larger than expected along with a measure of statistical evidence. With this approach, correlations between all pairs of ROIs are assessed as part of a single model rather than many independent statistical tests.

neuroscience↗