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.

Consequences of neural asynchrony: A case of auditory neuropathy

“…Auditory neurons in cortex increase synchrony and precision of firing with increases in stimutials were particularly well-formed in amplitude and morphology. Moreover, her perception of fine-grained lus intensity (Phillips and Hall 1990). Possibly IT cannot profit from this mechanism because, in her differences along a /ba-wa/ continuum was extraordinarily good, possibly reflecting neural reorganization case, neural input into auditory cortex lacks onset precision in the first place.…”

“…A high degree of temporal precision nous activity across a population of neurons. It should be emphasized, however, that cortical potentials reflect is also required to encode rapid formant transitions (Phillips et al 1989;Phillips and Hall 1990). In the case neural synchrony differently than the ABR.…”

“…Representation of timing information in speech of words in a single-talker condition, relative to a multiple-talker condition, suggests that she is able to make Rosen (1992) and Phillips (Phillips et al 1989;Phillips and Farmer 1990) have provided frameworks for conefficient use of the talker-specific consistencies in the acoustic signal (e.g., voice/source, individual articulasidering speech signals in the time domain. For example, suprasegmental components of speech typically tory characteristics that remain relatively stable across items in a list, fundamental frequency) to help her are expressed over hundreds or thousands of milliseconds, periodicity of the fundamental frequency occurs extract important linguistic information.…”

Estudo da vantagem da orelha direita em teste de detecção de gap

“…15 The precision of the first neural firing that responds to the onset of sound is proportional to the neural response latency. Phillips and Hall 13 found latency as short as 0.45 -1.5 ms for first neural firing in the auditory cortex of cats. These values are very close to those observed in the cochlear nerve and the cochlear nucleus, suggesting that temporal fidelity for transitory responses is preserved in afferent pathways until the primary auditory cortex.…”

“…5,10,11 Other studies, however, have shown that processing is more central. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Temporal resolution depends on the separation of different auditory stimuli; the role of the initial part of the stimulus and the coding precision of this response are crucial. 19,24 Auditory cortex neurons are particularly sensitive to these initial transitory stimuli, including the beginning of periodic events, the incident modulation of other periodic signals o the acoustic events that occur naturally in vocalization.…”