Shayam Suseelan - The Neural Correlates of Simple Visual Hallucinations

Simple geometric visual hallucinations arise from spontaneous activity in the primary visual cortex that is projected outward through the retinotopic map. Changes in the local excitation-inhibition balance of pyramidal neurons and interneurons in the brain underpin these phenomena, which can be accurately modeled using reaction-diffusion systems. Computational models demonstrate that increasing excitability while maintaining inhibition leads to more complex, global, and spatially organized geometric imagery as seen at higher psychedelic doses. Increased neural activity and the associated disruption of alpha oscillations are key components in the formation of these complex patterns when standard inhibitory controls are relaxed.