Membrane potential and conductance changes underlying length tuning of cells in cat primary visual cortex
Membrane potential and conductance changes underlying length tuning of cells in cat primary visual cortex
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DOI：
10.1523/jneurosci.21-06-02104.2001
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发表时间：
2001-03-15
影响因子：
5.3
通讯作者：
Ferster, D
中科院分区：
文献类型：
--
作者：
Anderson, JS;Lampl, I;Ferster, D
猫初级视皮层的许多细胞的棘波响应针对漂移光栅刺激的长度进行了优化。比这个最佳长度更长或更短的刺激引起次最大峰电位反应。为了研究这种长度调谐的机制，我们记录了猫的视觉皮层神经元的细胞内，同时呈现不同长度的漂移光栅刺激。我们已经发现，细胞的膜电位响应也表现出长度调谐，但是在比优选长度更长的长度处对尖峰响应的抑制比对膜电位响应的相应抑制强30-50%。这种差异可能归因于尖峰阈值的影响。此外，使用稳定的注入电流，我们已经测量了不同长度的刺激诱发的输入电导的兴奋性和抑制性成分的变化。我们发现，与最佳刺激相比，长刺激引起抑制性电导的增加和兴奋性电导的减少。这两种机制在它们的对比敏感度上不同，导致对于高对比度刺激而言更强的末端停止和更短的最佳长度。这些模式表明，长刺激的反应抑制是由兴奋性感受野外刺激的主动抑制以及其他皮质细胞本身末端抑制的兴奋减少的组合产生的。
Spike responses for many cells of cat primary visual cortex are optimized for the length of a drifting grating stimulus. Stimuli that are longer or shorter than this optimal length elicit submaximal spike responses. To investigate the mechanisms responsible for this length tuning, we have recorded intracellularly from visual cortical neurons in the cat while presenting drifting grating stimuli of varying lengths. We have found that the membrane potential responses of the cells also exhibit length tuning, but that the suppression of spike responses at lengths longer than the preferred is 30-50% stronger than the corresponding suppression of the membrane potential responses. This difference may be attributed to the effects of spike threshold. Furthermore, using steady injected currents, we have measured changes in the excitatory and inhibitory components of input conductance evoked by stimuli of different lengths. We find that, compared with optimal stimuli, long stimuli evoke both an increase in inhibitory conductance and a decrease in excitatory conductance. These two mechanisms differ in their contrast sensitivity, resulting in stronger end stopping and shorter optimal lengths for high-contrast stimuli. These patterns suggest that response suppression for long stimuli is generated by a combination of active inhibition from stimuli outside the excitatory receptive field, as well as decreased excitation from other cortical cells that are themselves end-inhibited.