Visual Perception

Tests whether age-related visual deficits arise from disrupted alpha-gamma coupling in visual cortex (V1) and MT. Uses fMRI, source-resolved HD-EEG, and personalized complex-waveform HD-tACS to (1) quantify aging effects on phase-amplitude coupling, (2) drive PAC into a preferred "gamma-at-alpha-troughs" state, and (3) bidirectionally change perception by aligning gamma to alpha troughs vs peaks. Two five-day, double-blind, sham-controlled studies (n=120 each) target contrast sensitivity (V1) and 3D shape-from-motion (MT), aiming for mechanistic insight and remediation in older adults with implications for ADRD.

The goal of this observational study is to learn how well the Oxford Visual Perception Screening (OxVPS) tool can identify stroke survivors with visual perception difficulties. The main aim is to determine the accuracy and utility of the OxVPS compared to the current gold standard assessment in stroke survivors. In other words, how well can the Oxford Visual Perception Screening tool (OxVPS) identify stroke patients with visual perception problems? Participants will completed the OxVPS and the current gold standards visual perception screening tool.