Rasche, Samuel E.; (2024) Experience-dependent connections in the brain. Doctoral thesis (Ph.D), UCL (University College London).

Preview

Text PhD_Thesis_Samuel_Rasche.pdf - Accepted Version Download (3MB) | Preview

Abstract

This thesis is an exploration of connections between cortical areas that become demonstrable through specific experiences, which I refer to as experience-dependent connections. By employing both univariate and multivariate analyses, the investigation delves into the neural mechanisms orchestrating various experiences, ranging from the conscious perception of single visual attributes to aesthetic experiences. I begin by addressing the neural mechanisms involved in conscious perception in the Riddoch syndrome. These patients are blinded by damage to V1 yet can consciously perceive motion presented in their blind field. Previous evidence, as well as ours, suggests that this residual ability may be retained after damage if the visual area important for motion perception, V5, is intact and receives direct input from the subcortex. These connections with the subcortex are critical, as we demonstrate in one of our patients that even partial damage to these pathways can lead to loss of sight and to conditions that mimic the Riddoch syndrome. Moreover, we show that the patients’ performance on visual discrimination tasks and their certainty of having seen motion strongly correlate, and specific neural activity patterns emerge in V5 only when a patient is conscious of motion. Thus, V1 is not necessary for conscious awareness of visual motion. Finally, we observed additional experiential states in these patients; they may, for example, experience hallucinations of motion. These experiences engaged additional areas, thereby revealing distinct brain connections depending on the experience. Having thus established that awareness of a single visual attribute evokes specific neural activity patterns in visual sensory areas outside V1, we enquired whether such patterns also emerge with more complex experiences. To this end, we investigated the neural determinants of aesthetic experiences. Only when stimuli were experienced as beautiful or ugly did patterns emerge in face-perceptive areas and was there co-activity with the medial orbitofrontal cortex. Overall, these findings show that the existence and high specificity of functional connections become demonstrable during certain experiences.

Download activity - last month

Export as JSONXMLCSV

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item