A comparison of tone-evoked response properties of 'cluster' recordings and their constituent single cells in the auditory cortex.

This study examined relationships between some acoustic response properties of 'cluster' recordings (CL) and their constituent single cells (SU) in the auditory cortex obtained from 22 clusters comprised of 63 responsive single units mainly in the anterior tonotopic field of the waking guinea pig. Response parameters included characteristic frequency (CF), threshold (Th) at CF, bandwidth 10 (BW10) and 30 (BW30) dB above Th. Clusters and single units were classified by their pattern of discharges as either 'onset' or 'sustained' response types. Comparison of CL and their constituent SU revealed differences in one or more response parameters in all CL. The CFs of onset CL were generally the same as the CFs of their constituent onset SU in contrast to sustained CL for which greater differences were observed in CF. The Th of all CL differed from that of some of their cells. The BW of approximately 50% of CL differed from their SU. The findings indicate that cluster recordings are often not good predictors of the response parameters of all of their constituent neurons.