PT  - JOURNAL ARTICLE
AU  - Andriani Rina
AU  - Amalia Papanikolaou
AU  - Zong Xiaopeng
AU  - Dorina T. Papageorgiou
AU  - Georgios A. Keliris
AU  - Stelios M. Smirnakis
TI  - Visual Motion Coherence Responses in Human Visual Cortex
AID  - 10.1101/2021.10.18.464860
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.10.18.464860
4099  - http://biorxiv.org/content/early/2021/10/20/2021.10.18.464860.short
4100  - http://biorxiv.org/content/early/2021/10/20/2021.10.18.464860.full
AB  - Random dot kinematograms (RDKs) have recently been used to train subjects with cortical scotomas to perform direction of motion discrimination, partially restoring visual motion perception. To study recovery of visual perception, it is important to understand how visual areas in normal subjects and subjects with cortical scotomas respond to RDK stimuli. Studies in normal subjects have shown that Blood Oxygen Level Dependent (BOLD) responses in human area hV5/MT+ increase monotonically with coherence, in general agreement with electrophysiology studies in primates. However, RDK responses in prior studies were obtained while the subject was performing fixation, not a motion discrimination condition. Furthermore, BOLD responses were gauged against a baseline condition of uniform illumination or static dots, potentially decreasing the specificity of responses for the spatial integration of local motion signals (motion coherence). Here we revisit this question starting from a baseline RDK condition of no coherence, thereby isolating the component of BOLD response due specifically to the spatial integration of local motion signals. In agreement with prior studies, we found that responses in area hV5/MT+ of healthy subjects were monotonically increasing when subjects fixated without performing a motion discrimination task. In contrast, when subjects were performing an RDK direction of motion discrimination task, responses in area hV5/MT+ remained flat, changing minimally, if at all, as a function of motion coherence. A similar pattern of responses was seen in area hV5/MT+ of subjects with dense cortical scotomas performing direction of motion discrimination for RDKs presented inside the scotoma. Passive RDK presentation within the scotoma elicited no significant hV5/MT+ responses. These observations shed further light on how visual cortex responses behave as a function of motion coherence, helping to prepare the ground for future studies using these methods to study visual system recovery after injury.Competing Interest StatementThe authors have declared no competing interest.hV5human Visual 5 areaMT+middle temporal area complexRDKsRandom dot kinematogramsfMRIFunctional magnetic resonance imagingBOLDBlood Oxygen Level Dependent