RT Journal Article
SR Electronic
T1 The Synaptic Representation of Sound Source Location in Auditory Cortex
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 14127
OP 14135
DO 10.1523/JNEUROSCI.2061-09.2009
VO 29
IS 45
A1 Paul Chadderton
A1 John P. Agapiou
A1 David McAlpine
A1 Troy W. Margrie
YR 2009
UL http://www.jneurosci.org/content/29/45/14127.abstract
AB A key function of the auditory system is to provide reliable information about the location of sound sources. Here, we describe how sound location is represented by synaptic input arriving onto pyramidal cells within auditory cortex by combining free-field acoustic stimulation in the frontal azimuthal plane with in vivo whole-cell recordings. We found that subthreshold activity was panoramic in that EPSPs could be evoked from all locations in all cells. Regardless of the sound location that evoked the largest EPSP, we observed a slowing in the EPSP slope along the contralateral–ipsilateral plane that was reflected in a temporal sequence of peak EPSP times. Contralateral sounds evoked EPSPs with earlier peak times and consequently generated action potential firing with shorter latencies than ipsilateral sounds. Thus, whereas spiking probability reflected the region of space evoking the largest EPSP, across the population, synaptic inputs enforced a gradient of spike latency and precision along the horizontal axis. Therefore, within auditory cortex and regardless of preferred location, the time window of synaptic integration reflects sound source location and ensures that spatial acoustic information is represented by relative timings of pyramidal cell output.