PT  - JOURNAL ARTICLE
AU  - Jingyang Zhou
AU  - Noah C. Benson
AU  - Kendrick Kay
AU  - Jonathan Winawer
TI  - Systematic changes in temporal summation across human visual cortex
AID  - 10.1101/108639
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 108639
4099  - http://biorxiv.org/content/early/2017/02/14/108639.short
4100  - http://biorxiv.org/content/early/2017/02/14/108639.full
AB  - The visual system analyzes image properties across multiple spatial and temporal scales. Population receptive field (“pRF”) models have successfully characterized spatial representations across the human visual pathways. Here, we studied temporal representations, measuring fMRI and electrocorticographic (“ECoG”) responses in posterior, lateral, ventral, and dorsal visual areas to briefly viewed contrast patterns. We built a temporal pRF model employing linear summation and time-varying divisive normalization. Our model accurately predicts the fMRI amplitude and ECoG broadband time-course, accounting for two phenomena – accumulation of stimulus information over time (summation), and response reduction with prolonged or repeated exposure (adaptation). We find systematic differences in these properties: summation periods are increasingly long and adaptation more pronounced in higher compared to earlier visual areas. We propose that several features of temporal responses – adaptation, summation, and the timescale of temporal dynamics – can be understood as resulting from a small number of canonical neuronal computations.