[입시] [뇌과학세미나] 10월10일(목) 16시 세미나 안내입니다.
[뇌과학 세미나]
연 자 : 정민환 교수 (KAIST)
제 목 : Neural correlates of time interval estimation in rat medial prefrontal cortex
일 시 : 2013년 10월 10일 (목) 16:00
장 소 : 16-1동(사회대 신양 ) 405호
Abstract :
Time interval estimation is involved in numerous behavioral processes, but its underlying neural mechanisms remain unclear. In particular, it has been controversial whether time is encoded on a linear or logarithmic scale. As an effort to reveal neural processes underlying interval timing, we examined neuronal activity in the medial prefrontal cortex (mPFC) in rats performing a temporal bisection task. We have shown previously that inactivation of the mPFC profoundly impairs animal’s ability to discriminate time intervals in the same task (Kim et al., 2009, Front Behav Neurosci, 3:38). We found that mPFC neuronal population conveyed precise information about the elapse of time with their activity tightly correlated with the animal's choice of target. Further analysis yielded several lines of converging evidence that rat mPFC represents the elapse of time based on linearly changing activity of individual neurons on a logarithmic time scale. First, the largest variance of neural activity was explained by a logarithmic function that was in charge of a large fraction of temporal information. Second, logarithmic functions were superior to linear functions in explaining activity of individual mPFC neurons, and the extent to which a logarithmic function can explain a neuronal activity profile (R2 value) was significantly correlated with the amount of temporal information each neuron carried. Third, the precision of time interval discrimination based on neural activity was lowered in proportion to the elapse of time, but without proportional increase in neural variability, which is well accounted for by logarithmic, but not by linear functions. These findings suggest that the mPFC is part of an internal clock in charge of controlling interval-timing behavior, and that linearly changing neuronal activity on a logarithmic time scale is one way of representing the elapse of time in the brain, which might a reason why the precision of time interval discrimination is lowered in proportion to its duration according to Weber’s law.
주 최 : 미래창조과학부 뇌인지과학 연구사업
문 의 : 880-6442, windy@snu.ac.kr