PhD Talks: Sensation & Perception

1. Emel Küçük 'Mapping the third visual pathway using naturalistic stimuli'. Abstract: The third visual pathway proposes a network of brain regions specialised for social perception. Using naturalistic stimuli, researchers have investigated brain regions involved in social perception and how they respond to dynamic social interactions depicted in films. This study aims to extend previous findings and investigate the functional connectivity between regions in the third visual pathway. In the MRI scanner, participants (n=26) viewed 8-minute audiovisual clips representing three different levels of social interaction. This included multiple characters interacting with each other (high social interaction), a monologue from one character (low social interaction) and landscapes presented with background music (no social interaction). Additionally, 8 minutes of resting-state data was collected. It is hypothesised that regions within the third visual pathway, such as the superior temporal sulcus, would demonstrate greater activity and stronger functional connectivity when viewing scenes of high social interaction compared to scenes with low and no social interactions. Through combining naturalistic stimuli and functional connectivity analyses, this study provides a greater understanding of how distributed brain regions coordinate to process social interactions. Such research encourages future studies on individual differences or how clinical populations may engage the third visual pathway during social perception.

2. Shasha Wei 'Altered vibration signal combination in patients with chronic hand pain' Abstract: Chronic hand pain is frequently accompanied by diminished tactile acuity and modified somatosensory processing, likely reflecting an altered excitatory-inhibitory balance within the primary somatosensory cortex (S1). However, it remains unclear whether chronic hand pain affects tactile processing. This study aims to investigate whether vibrotactile signal processing is disrupted in chronic hand pain by assessing corresponding brain responses. Twenty-five participants with chronic hand pain and 25 age-matched controls were tested under three stimulation conditions: “Alternating-26 Hz” (five fingers stimulated at 26 Hz), “Full-26 Hz” (ten fingers stimulated at 26 Hz), and “Interleaved-26/23 Hz” (five fingers at 26 Hz and five fingers at 23 Hz). Across all conditions, the chronic pain group exhibited significantly larger EEG signal-to-noise ratios (SNRs) than controls (p < 0.001), indicating enhanced cortical responses to mechanical stimulation. Computational modelling using a hyperbolic ratio function further revealed reduced semi-saturation constants (C₅₀) in the pain group, consistent with increased cortical sensitivity. Together, these findings provide electrophysiological and computational evidence for enhanced cortical responsiveness to tactile input in chronic hand pain.

3. Aaron Cousins 'From stomach to self-image: the connection between gastrointestinal interoception and body image and its implications for eating disorders'