摘要
初级视皮层神经元对周期性运动光栅刺激具有周期性持续响应,而对没有周期性变化的静止恒定刺激的响应主要集中在刺激呈现的初期,为瞬时性响应.我们研究了在5～50 ms短时长静止刺激下神经元的响应性质,对响应时程的分析表明,猫初级视皮层神经元对瞬态刺激的响应曲线呈波峰形式.随着刺激的出现,在经过一段延迟后,响应幅度上升,出现一个或多个响应峰,随刺激的消失,响应幅度下降.神经元表现出随刺激时长的增长,响应峰主峰(第一个峰)的峰值时间和峰宽都有增加的趋势,但峰值时间在30～50 ms趋于饱和,除5 ms刺激时长诱发的峰高明显降低以外,其他刺激时长诱发的峰高较恒定.刺激消失变为灰屏时,神经元会产生撤反应峰(刺激后发放,offset responses),其强度由前面的刺激时长决定.最小响应时长约为39 ms,主峰与撤峰的最小时间差为36 ms,二者十分相近,提示了视初级视皮层神经元的基本响应时间约为35～40 ms.这可能是"视觉暂留"现象在初级视皮层水平的生理基础.
Neurons in primary visual cortex （V1） have periodical responses to smoothly drifting gratings, but only have transient responses to the static stimuli that evoke drastic responses at the initial tens of milliseconds. This hints that the information of stimuli could be processed primarily in this initial period. Study on neuronal responses during this period is critical for understanding the characters of neuronal responses to the static stimuli. We investigated the temporal response time courses of V1 neurons to six stimulus durations （5, 10, 20, 30, 40, and 50 ms） of static gratings. Responses to the static stimuli were denoted by the time course curves which were the contours of the Peri-Stimulus Time Histograms （PSTHs） with a resolution of 1 ms bin. Along with the prolongation of the stimulus duration, PSTH curves to different stimulus durations reflected the evolution of responses to the static stimuli. All the data were collected from the anesthetized cat V1 with extracellular unit recording. V1 neurons showed wave-like response curves that grew up after a short latency to the stimulus onset and then dropped off gradually due to the stimulus offset. When stimulus duration prolonged, the time and width of the main peak （the first peak, the largest one, of PSTH response curve） increased and saturated at 30 ms stimulus duration that we tested. Magnitudes of most main peaks were almost equal except that the response peak to the 5 ms stimulus duration was significantly lower than those to the others. There were also offset response peaks which were evoked by the stimulus offset, but were smaller than the main peaks and contained less information about visual stimuli. The magnitude of the offset responses increased with the stimulus duration, so it could be regarded as the aftereffects of the stimulus offset. Statistically, the response durations （represented by 2 x half peak width） of V1 neurons to different stimulus durations were not shorter than 39 ms （even the stimulus duration was as sh
出处
《生物化学与生物物理进展》
SCIE
CAS
CSCD
北大核心
2012年第12期1190-1196,共7页
Progress In Biochemistry and Biophysics
基金
国家高技术研究发展计划(863)(2007AA02Z313)
国家自然科学基金(30570587
30623004)
中国科学院知识创新工程(KSCX1-YW-R-32)资助项目~~
关键词
初级视皮层
神经元
响应时程
主峰
副峰
撤反应峰
基本信息响应时间
primary visual cortex, neuron, response time course, main peak, side peak, offset peak, minimal timefor information processing
