Long-term enhanced desynchronization of the alpha rhythm following tetanic stimulation of human visual cortex.
It had been shown previously that a photic tetanus induces LTP-like changes in the visual cortex, as indexed by an enhancement of the N1b component of the visual evoked potential, recorded non-invasively by electroencephalography. This potentiation was shown to last over 1 h. In the present study, the effect of a photic tetanus on oscillatory activity is investigated. EEGs were collected from eight healthy subjects in three conditions while visual checkerboards were displayed. Following baseline presentations in two conditions a lateralized visual tetanus was given, either to the left or right visual field, and in a third condition no tetanus was given. This was followed by a return to baseline presentations, both immediately after the tetanus/control block, and 1 h later. Enhanced event-related desynchronization (ERD) of the alpha rhythm lasting 1 h was seen following the photic tetanus over occipital electrodes. Because ERD of the alpha rhythm is thought to represent active cortex, these results suggest that the visual tetanus induces long-lasting cortical changes, with stronger neuronal assemblies and increased neuronal output.
Clapp
Wesley C
WC
Psychology Department, City Campus, Centre for Cognitive Neuroscience, University of Auckland, Private Bag 92019, Auckland, New Zealand. w.clapp@auckland.ac.nz
Muthukumaraswamy
Suresh D
SD
Hamm
Jeff P
JP
Teyler
Tim J
TJ
Kirk
Ian J
IJ
D000328:Adult; D000513:Alpha Rhythm; D003344:Cortical Synchronization; D005074:Evoked Potentials, Visual; D006801:Humans; D017774:Long-Term Potentiation; D008297:Male; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*