Classification of single unit responses in the auditory cortex of cats

Conclusions

• 1. If the stability of the response to repeated presentation of an auditory stimulus is used as the criterion, neurons of the auditory cortex of anesthetized cats may be divided into stable and variable types.

• 2. The “stable” neurons are characterized by the presence of a response to each subsequent stimulation and by constancy of the temporal pattern of the response despite frequent repetition of the stimulus. The possibility that the early discharges of stable neurons and the primary evoked potential in the auditory cortex may be interconnected and mutually dependent is discussed.

• 3. Some “variable” neurons, after frequent repetition of the stimulus, retain the information received about the stimulus for a long time, as reflected in the pattern of the impulses corresponding to that particular stimulus. This phenomenon is regarded as a reflection of “short-term” or “operative” memory at the neuronal level. The response of other “variable” neurons to repetition of the stimulus, on the other hand, shows extinction.

• 4. “Variable” neurons show no apparent regular pattern in the variability of the response to repetition of the stimulus.

• 5. It may be postulated that the long storage of information about a signal in the case of some neurons and extinction of the response in the case of other neurons when the signal is repeated may be due to “habituation” to the signal, or in other words, to “training.”

• 6. The possible role of the phenomena described in the neurophysiological mechanisms lying at the basis of the “subconscious” or of “subsensory sensitivity” is considered.