Physiology of perception

Cortical stimulation and recording in humans

P. G. Ray, K. J. Meador, J. R. Smith, James Wheless, M. Sittenfeld, G. L. Clifton

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Objectives: 1) To determine the effect of stimulus train duration (TD) on sensory perception using direct stimulation of somatosensory and visual cortices. 2) To investigate the occurrence of evoked potentials in response to stimulation that is subthreshold for perception. Background: Studies of the mechanisms of conscious perception using direct cortical stimulation and recording techniques are rare. The clinical necessity to implant subdural electrode grids in epilepsy patients undergoing evaluation for surgery offers an opportunity to examine the role of stimulus parameters and evoked potentials in conscious perception. Methods: Subjects included epilepsy patients with grids over somatosensory or occipital cortex. Single pulses (100 microseconds) and stimulus trains were applied to electrodes, and thresholds for perception were found. Evoked potentials were recorded in response to peripheral stimulation at intensities at, above, and below sensory threshold. Results: During cortical stimulation, sensory threshold changed little for stimulus trains of 250 milliseconds and longer, but increased sharply as TD decreased below this level Primary evoked activity was recorded in response to peripheral stimulations that were subthreshold for conscious perception. Conclusions: The results confirm a previous report of the effects of stimulus TD on sensory threshold. However, no motor responses occurred following somatosensory stimulation with short trains, as previously reported. The TD threshold pattern was similar in visual cortex. In agreement with the previous report, early components of the primary evoked response were not correlated with conscious sensory awareness.

Original languageEnglish (US)
Pages (from-to)1044-1049
Number of pages6
JournalNeurology
Volume52
Issue number5
StatePublished - Mar 23 1999

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Sensory Thresholds
Evoked Potentials
Somatosensory Cortex
Visual Cortex
Epilepsy
Electrodes
Occipital Lobe

All Science Journal Classification (ASJC) codes

  • Clinical Neurology

Cite this

Ray, P. G., Meador, K. J., Smith, J. R., Wheless, J., Sittenfeld, M., & Clifton, G. L. (1999). Physiology of perception: Cortical stimulation and recording in humans. Neurology, 52(5), 1044-1049.

Physiology of perception : Cortical stimulation and recording in humans. / Ray, P. G.; Meador, K. J.; Smith, J. R.; Wheless, James; Sittenfeld, M.; Clifton, G. L.

In: Neurology, Vol. 52, No. 5, 23.03.1999, p. 1044-1049.

Research output: Contribution to journalArticle

Ray, PG, Meador, KJ, Smith, JR, Wheless, J, Sittenfeld, M & Clifton, GL 1999, 'Physiology of perception: Cortical stimulation and recording in humans', Neurology, vol. 52, no. 5, pp. 1044-1049.
Ray PG, Meador KJ, Smith JR, Wheless J, Sittenfeld M, Clifton GL. Physiology of perception: Cortical stimulation and recording in humans. Neurology. 1999 Mar 23;52(5):1044-1049.
Ray, P. G. ; Meador, K. J. ; Smith, J. R. ; Wheless, James ; Sittenfeld, M. ; Clifton, G. L. / Physiology of perception : Cortical stimulation and recording in humans. In: Neurology. 1999 ; Vol. 52, No. 5. pp. 1044-1049.
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