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 M. Barbaro

Research output: Contribution to journalArticle

100 Scopus citations

Abstract

SUMMARY. 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
DOIs
StatePublished - Aug 1 1991

ASJC Scopus subject areas

  • Clinical Neurology

Fingerprint Dive into the research topics of 'Control of the transition from sensory detection to sensory awareness in man by the duration of a thalamic stimulus: The CEREBRAL 'time-on' factor'. Together they form a unique fingerprint.

  • Cite this