Spin-L共催　生理学研究所 感覚認知情報研究部門 公開セミナーを10月16日（木）に開催します。

今回のセミナーでは、MRIを用いた高次視覚機能研究の専門家である、Stanford UniversityのKalanit Grill-Spector先生に最新の研究成果についてご講演いただくことになりました。
本セミナーは、オンサイトのみの開催を予定しておりますので、会場まで直接お越しください。（事前の登録などは不要です。）
Grill-Spector先生より、直接お話をお伺いできる貴重な機会です。皆様のご参加をお待ちしております。

Understanding cognitive processing in the human visual system using spatiotemporal population receptive fields

Kalanit Grill-Spector, Ph.D (Stanford University, USA)

A key goal of cognitive neuroscience is to generate an understanding of the functional neuroanatomy of cortical systems. fMRI and computational modeling have transformed our understanding of the human brain. In the visual system, modeling population receptive fields (pRF) led to discoveries of multiple maps of pRF eccentricity, polar angle, and size as well as explained cognitive phenomena like spatial attention and the face inversion effect. However, due to the low temporal resolution of fMRI and the low spatial resolution of EEG/MEG it is unknown what is the nature of spatiotemporal computations in the human brain.

Using computational encoding models and the visual system as a model system, I will describe recent empirical and computational innovations that have advanced understanding of key cognitive neuroscience questions. Specifically, I will describe a new empirical and computational framework for estimating from fMRI data the spatiotemporal population receptive field (ST-pRF) of each voxel in the visual system in units of visual degrees and milliseconds. I will start by showing how we tested and validated the ST-pRF framework vs. ground truth data. Then, we use this framework to elucidate the spatiotemporal computations across the human visual system for the first time, finding that spatial and temporal windows as well as compressive nonlinearities increase systematically across the visual hierarchy. With this understanding in hand, we then assess how simple, bottom-up computations by ST-pRFs may affect visual capacity and explain elusive phenomena like why neural responses are suppressed when multiple visual stimuli are presented at once compared to one after the other in sequence. I will end by discussing the relevance of this powerful spatiotemporal pRF framework for understanding other sensory and cognitive systems in the brain.