RT Journal Article
SR Electronic
T1 Generation of Spike Latency Tuning by Thalamocortical Circuits in Auditory Cortex
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 9969
OP 9980
DO 10.1523/JNEUROSCI.1384-12.2012
VO 32
IS 29
A1 Yi Zhou
A1 Lukas Mesik
A1 Yujiao J. Sun
A1 Feixue Liang
A1 Zhongju Xiao
A1 Huizhong W. Tao
A1 Li I. Zhang
YR 2012
UL http://www.jneurosci.org/content/32/29/9969.abstract
AB In many sensory systems, the latency of spike responses of individual neurons is found to be tuned for stimulus features and proposed to be used as a coding strategy. Whether the spike latency tuning is simply relayed along sensory ascending pathways or generated by local circuits remains unclear. Here, in vivo whole-cell recordings from rat auditory cortical neurons in layer 4 revealed that the onset latency of their aggregate thalamic input exhibited nearly flat tuning for sound frequency, whereas their spike latency tuning was much sharper with a broadly expanded dynamic range. This suggests that the spike latency tuning is not simply inherited from the thalamus, but can be largely reconstructed by local circuits in the cortex. Dissecting of thalamocortical circuits and neural modeling further revealed that broadly tuned intracortical inhibition prolongs the integration time for spike generation preferentially at off-optimal frequencies, while sharply tuned intracortical excitation shortens it selectively at the optimal frequency. Such push and pull mechanisms mediated likely by feedforward excitatory and inhibitory inputs respectively greatly sharpen the spike latency tuning and expand its dynamic range. The modulation of integration time by thalamocortical-like circuits may represent an efficient strategy for converting information spatially coded in synaptic strength to temporal representation.