Spatial and temporal processing of single auditory cortical neurons and populations of neurons in the macaque monkey

The auditory cortex is known to be a necessary neural structure for the perception of acoustic signals, particularly the spatial location and the temporal features of complex auditory stimuli. Previous studies have indicated that there is no topographic map of acoustic space in the auditory cortex and it has been proposed that spatial locations are represented by some sort of population code. Additionally, in spite of temporal processing deficits being one of the hallmark consequences of normal aging, the temporal coding of acoustic stimuli remains poorly understood. This report will address these two issues by discussing the results from several studies describing responses of single auditory cortical neurons in the non-human primate. First, we will review studies that have addressed potential spike-rate population codes of acoustic space in the caudal belt of auditory cortex. Second, we will present new data on the neuronal responses to gap stimuli in aged monkeys and compare them to published reports of gap detection thresholds. Together these studies indicate that the alert macaque monkey is an excellent model system to study both spatial and temporal processing in the auditory cortex at the single neuron level.