A neural network underpinning emotion judgments from faces and bodies revealed by effective connectivity
In a previous study (Atkinson, Vuong & Smithson, 2012), we provided evidence of modulation of face- and body-selective cortical regions by the emotion expressed in point-light face and body stimuli. In the present study, we first performed a whole-brain analysis with this data set to identify regions involved in emotion (vs. colour) judgments on these same stimuli, which included inferior occiptotemporal cortex, inferior frontal gyri, superior temporal sulcus, supramarginal gyrus, insula and amygdala. We then performed dynamic causal modeling to determine the pattern of effective connectivity between these regions. The results revealed a strongly feedforward and feedback hierarchical neural network for understanding others’ (emotional) actions. The left pulvinar and right amygdala were central hubs of this network, highlighting their modulatory role (Pessoa & Adolphs, 2010).
Population receptive field-based fMRI to identify the implantation site(s) for neural prosthetics.
Neural prosthetics have the potential to assist paralysed patients by extracting brain signals to drive computers or robots. fMRI results will provide an across brain area comparison of the relative weight of optimal bio-engineering parameters for neural prosthesis. This project is expected to accelerate prosthetic development and deliver solutions to the paralyzed population.
An investigation of the co-involvement of parietal and frontal regions in a visual search task revealed by tDCS and fMRI.
This study showed that when cathodal tDCS is applied to decrease the activity of right posterior parietal cortex (PPC) this not only has a behavioural effect in the processing of a visual search task but also results in decreased activity in bilateral frontal regions. Therefore, the behavioural effect seen in this task is due to a hitherto uncovered network effect driven by an unstimulated region.
The influence of biological and social factors on individual differences in functional brain organization.
We have conducted a study on the influence of stereotype threat on neural correlates of and performance on a mental rotation task. In general, we are interested in studying biological (e.g. hormones) or social (e.g. stereotypes) influences on individual differences in neural correlates of certain cognitive or emotional tasks.
(Real-time) fMRI of motivational cue reactivity.
Visual cues in the environment signalling the availability of rewards (e.g. images showing drugs or appetitive food) can acquire ‘incentive salience’ and trigger ‘wanting' and craving responses, especially during heightened motivational states, such as hunger or abstinence. By using fMRI and behavioural techniques, the present project seeks to better understand the neural and behavioural dynamics underlying such visual cue reactivity during exposure to food and drug stimuli. One specific question which is addressed in the project is whether neural cue reactivity, ‘wanting’ and craving can be altered (e.g. reduced) by neurofeedback-guided self-regulation. In this technique participants receive symbolic feedback about their brain signals during fMRI scanning. Based on real-time fMRI analysis methods, this approach allows individuals to monitor and potentially to regulate their brain responses in key motivational areas during cue exposure.
Cortical processing of edge- and surface-based properties of colour and texture.
The aim is to identify specific areas of the cortex that independently process the edge and surface properties of the visual attributes colour and texture.
Characterizing color representations in the visual cortex with fMRI.
The processing of color information in the retina and early visual cortex is relatively well-understood based on psychophysics and single-unit electrophysiology, but much less is known about how color is processed in higher-level visual areas. Specifically, we don't currently understand the neural mechanisms behind the transformation of color sensations into context-invariant representations of object color, or the mechanisms of learning and remembering color. In this project, I will first localize different visual areas responsive to color, and will then proceed to study the transformation of color from a sensory representation to an invariant object color representation. Methods will include both univariate and multivariate fMRI data analyses.
Neural Correlates of Motion Processing through Echolocation, Source Hearing and Vision in Blind Echolocation Experts and Sighted Echolocation Novices.
The study used fMRI to investigate neural substrates of motion processing through echolocation, source hearing and vision in the human brain, with particular emphasis on activity in in tempero-occipital cortex.
Neural correlates of face perception and memory
I am interested in the cognitive and neural processes underlying the perception of visually derivable (age, sex, ethnicity etc.) and identity-specific facial information. In addition, I examine face memory, and particularly why we are more accurate at remembering faces from our own ethnic and age groups.