Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus: The cerebral 'time-on' factor

Benjamin Libet, Dennis K. Pearl, David E. Morledge, Curtis A. Gleason, Yoshio Hosobuchi, Nicholas Barbaro

Research output: Contribution to journalArticle

97 Citations (Scopus)

Abstract

A 'time-on' theory to explain the cerebral distinction between conscious and unconscious mental functions proposes that a substantial minimum duration ('time-on') of appropriate neuronal activations up to about 0.5 s is required to elicit conscious sensory experience, but that durations distinctly below that minimum can mediate sensory detection without awareness. A direct experimental test of this proposal is reported here. Stimuli (72 pulses/s) above and below such minimum train durations (0-750 ms) were delivered to the ventrobasal thalamus via electrodes chronically implanted for the therapeutic control of intractable pain. Detection was measured by the subject's forced choice as to stimulus delivery in one of two intervals, regardless of any presence or absence of sensory awareness. Subjects also indicated their awareness level of any stimulus-induced sensation in each and every trial. The results show (1) that detection (correct > 50%) occurred even with stimulus durations too brief to elicit awareness, and (2) that to move from mere detection to even an uncertain and often questionable sensory awareness required a significantly larger additional duration of pulses. Thus simply increasing duration ('time-on') of the same repetitive inputs to cerebral cortex can convert an unconscious cognitive mental function (detection without awareness) to a conscious one (detection with awareness).

Original languageEnglish (US)
Pages (from-to)1731-1757
Number of pages27
JournalBrain
Volume114
Issue number4
StatePublished - Aug 1991
Externally publishedYes

Fingerprint

duration
Chemical activation
Electrodes
Intractable Pain
Implanted Electrodes
thalamus
cerebral cortex
Pain
Cortex
Thalamus
Cerebral Cortex
electrodes
Cognition
Electrode
Convert
Awareness
Factors
pain
Activation
therapeutics

ASJC Scopus subject areas

  • Neuroscience(all)
  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Mathematics(all)
  • Statistics and Probability
  • Agricultural and Biological Sciences (miscellaneous)
  • Clinical Neurology

Cite this

Libet, B., Pearl, D. K., Morledge, D. E., Gleason, C. A., Hosobuchi, Y., & Barbaro, N. (1991). Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus: The cerebral 'time-on' factor. Brain, 114(4), 1731-1757.

Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus : The cerebral 'time-on' factor. / Libet, Benjamin; Pearl, Dennis K.; Morledge, David E.; Gleason, Curtis A.; Hosobuchi, Yoshio; Barbaro, Nicholas.

In: Brain, Vol. 114, No. 4, 08.1991, p. 1731-1757.

Research output: Contribution to journalArticle

Libet, B, Pearl, DK, Morledge, DE, Gleason, CA, Hosobuchi, Y & Barbaro, N 1991, 'Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus: The cerebral 'time-on' factor', Brain, vol. 114, no. 4, pp. 1731-1757.
Libet, Benjamin ; Pearl, Dennis K. ; Morledge, David E. ; Gleason, Curtis A. ; Hosobuchi, Yoshio ; Barbaro, Nicholas. / Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus : The cerebral 'time-on' factor. In: Brain. 1991 ; Vol. 114, No. 4. pp. 1731-1757.
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