2023年10月27日　　Friday Lunch Seminar （英語で開催します）
12:15 〜 13:00
On-lineで開催いたします。
→申込みは　こちら
（締め切り：10月26日正午、参加要領は10月26日にeメールにてお知らせします。）

演題：Fast, faster, fastest in fMRI

クイーンズランド大学
研究員
程野 祥太

担当PI：竹村 浩昌

Abstract:
In this talk, I will present our work investigating the temporal sensitivity of Blood Oxygen Level Dependent (BOLD) based fMRI, the temporal specificity of Diffusion fMRI (DfMRI), and the challenges associated with Direct Imaging of Neuronal Activity (DIANA) in humans.

Gradient recalled echo (GRE) BOLD contrast allows inference of neuronal activity from associated hemodynamic changes. Therefore, the spatiotemporal sensitivity is influenced by the local vasculature architecture. The spatial specificity has been well studied, however the temporal aspects has been less explored. We have studied the frequency dependence of the BOLD signal to stimulus-driven hemodynamic responses in primally motor and somatosensory cortices (M1 and S1) using cortical depth as a proxy for the vascular hierarchy.

DfMRI has been proposed as a mean to detect more neuronally specific signal changes, possibly associated with activity induced cell-swelling. However, the field has struggled to reproduce key findings presented in the original paper. Commonly, attempts to reproduce these findings resulted in signals indistinguishable from BOLD. Using extremely short readouts, we were able to minimize BOLD contamination in DfMRI, revealing signal preceding the BOLD response by 1.6 seconds.

The recently proposed DIANA technique claims to offer neuronally specific fMRI with millisecond temporal resolution. We have attempted DIANA in humans and rats, but failed to observe reliable normally driven signals. I will conclude my talks by sharing our initial experiences about DIANA in humans, its challenges, and related technological developments.