Experimental Brain Research

, Volume 77, Issue 3, pp 451–475

Neuronal activity in the human lateral temporal lobe

I. Responses to speech
  • O. Creutzfeldt
  • G. Ojemann
  • E. Lettich
Article

DOI: 10.1007/BF00249600

Cite this article as:
Creutzfeldt, O., Ojemann, G. & Lettich, E. Exp Brain Res (1989) 77: 451. doi:10.1007/BF00249600

Summary

Single and multiple unit neuronal activity was recorded from the cortex of the lateral temporal lobe in conscious humans during open brain surgery for the treatment of epilepsy. Recordings were obtained from the right and left superior, middle and inferior temporal gyrus of 34 patients (41 recording sites). Recordings were restricted to regions to be resected during subsequent surgery. This excluded recordings from language areas proper. Neuronal responses to words and sentences presented over a loudspeaker and during free conversation were recorded. No significant differences between the right and left hemisphere were obvious. All neurons in the superior temporal gyrus responded to various aspects of spoken language with temporally well defined activation/inhibition patterns, but not or only little to non-linguistic noises or tones. Excitatory responses were typically short or prolonged (up to several hundred ms) bursts of discharges at rates above 20/sec, reaching peak rates of 50–100/s. Such responses could be specifically related to certain combinations of consonants suggesting a function in categorization, they could depend on word length, could differentiate between polysyllabic and compound words of the same length or could be unspecifically related to language as such. No formant specific responses were found, but the prolonged excitations across syllables suggest that consonant/vowel combinations may play a role for some activation patterns. Responses of some neurons (or neuronal populations) depended on the attention paid to the words and sentences, or the task connected with them (repeat words, speech addressed to the patient demanding something). Neurons in the middle and inferior temporal gyrus were only little affected by listening to single words or sentences, but some were unspecifically activated by words or while listening to sentences. Excitatory responses varied within a limited range of discharge rates usually below 5–10/s. Phonetic distortion of spoken language could reduce responses in superior temporal gyrus neurons, but also the slight changes in discharge rate of middle temporal neurons could be absent during distorted and uncomprehensible speech sounds. We conclude that superior temporal gyrus neuron responses reflect some general phonetic but not semantic aspects of spoken language. Middle and inferior temporal gyrus neurons do not signal phonetic aspects of language, but may be involved in understanding language under certain conditions.

Key words

Single unit recording Temporal lobe Listening to speech Man 

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • O. Creutzfeldt
    • 1
  • G. Ojemann
    • 2
  • E. Lettich
    • 2
  1. 1.Department of NeurobiologyMax-Planck-Institute for Biophysical ChemistryGöttingen-NikolausbergFederal Republic of Germany
  2. 2.Department of Neurological Surgery, RI 20University of WashingtonSeattleUSA

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