| 日 時 | 2007年07月18日(水) 15:00 より 16:30 まで |
|---|---|
| 講演者 | 小川 誠二 所長 |
| 講演者所属 | 財団法人 濱野生命科学研究財団小川脳機能研究所 |
| お問い合わせ先 | ナノ形態生理 永山 國昭 |
| 要旨 |
小川先生は、5年程前米国から帰国し、小川脳機能研の初代所長となりました。現在広く使われているｆMRIの基盤技法であるBOLD法をBell研究所研究員時代（1980年代）に創始しました。今回の所長招聘セミナーでは、下記要旨にあるように脳の構造と機能の本質に迫るお話を伺えるものと期待しています。 ポイは FMRI is a non-invasive method to detect some localized system activities of neuronal pools participating in performing a functional task in the brain. The signals based on CBF, CBV and BOLD are well coupled to the synaptic neuro activation, although the response time in seconds is far slow to follow the dynamics of neuronal activity that proceeds in 10s to 100s of milliseconds. There are other fMRI methods potentially overcome the shortcoming of the slow response, diffusion-sensitized fMRI or neuro current induced magnetic field detection. However, the characteristics and how they should be measured are still in their infancy. We have been using BOLD fMRI to explore some aspects of dynamic functional processes in terms of intra- and inter- system interaction. The details of these phenomena viewed at macroscopic size will help to understand how the functional anatomy of the brain is built up. By stimulation of the brain with a pair of identical or different inputs, the activation characteristics involving refractory suppression are examined to see intra-site interaction as well as inter-site interaction. The degree of interaction depends on the site in the pathway of signal processing. There at some sites the presence of sub functional units can be suggested and the extent of their interaction varies with the inputs to the site. Non-interacting sub sites, if any, means the spatial resolution of fMRI is not sufficient enough to resolve them. At some sites, inputs from two different stimuli of same category appear to be regarded as the same as judged by the strong suppressive response to the stimuli, although to the stimuli other sites respond as inputs are different. The functional composition of a site, either with weakly interacting or strongly interacting functional subunits, ie neuronal circuits from the pool of neurons in the site, can be distinguished from the mode of neuro function with the whole pool of neurons that contains individual neurons each assigned to a specific function. We believe the former mode of operation with localized sub functional units that have their specific roles. One may be able to see the plasticity of such small neuro-circuits and their behaviors. The knowledge of these detailed specificities and the mode of functional operation will help to construct functional architecture of the brain. |
