title: Response timing constraints on the cortical representation of sound time structure.
abstract: The precision of spike response timing of 94 primary auditory cortex neurons was studied using conventional extracellular recording techniques in barbiturate-anesthetized cats to which tone- and/or noise-burst stimuli were presented using sealed sound delivery systems. Precision of spike timing was indexed using the standard deviation of the first-spike latent period in responses evoked by repeated presentation of tonal stimuli systematically varied in frequency, amplitude, and/or repetition rate. Within a neuron, variability of first-spike timing was usually proportional to the mean first-spike latency, in agreement with previous reports. In cases where there was a systematic relation between the precision of response timing and the mean latency, a linear correlation accounted for up to 90% of the data variance. Across the 94 neurons, standard deviations seen in responses of minimum latency were related to minimal mean latencies, and were typically in the range from 0.15-1.5 ms. The data suggest that responses to transients in the cortex show a precision of spike timing which is only slightly worse than that seen in cochlear-nerve fibers. This, however, is in dramatic contrast to previous evidence on the steady-state temporal response of cortical cells, which is at least an order of magnitude poorer than that seen in auditory-nerve fibers and many cochlear nucleus cells. These observations may be directly relevant to the known consequences of auditory cortex pathology in man.
authors.affiliation: Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: D P
authors.initials: DP
authors.lastname: Phillips
authors.forename: S E
authors.initials: SE
authors.lastname: Hall
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology; D001303:Auditory Cortex / Q000502:physiology*; D002415:Cats; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D008144:Loudness Perception / Q000502:physiology; D009474:Neurons / Q000502:physiology; D010897:Pitch Discrimination / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*