Applying functional magnetic resonance imaging techniques, hemodynamic responses elicited by slowly flashing checkerboards (0.25 Hz) were measured both before and after a block of rapidly presented checkerboards (9 Hz – a ‘photic tetanus’) was delivered. It has been shown previously, using electroencephelography, that this photic tetanus potentiates components of the visual-evoked potential. In the present study, hemodynamic responses in the extrastriate visual cortex were significantly increased to checkerboards presented at a low frequency after the administration of the photic tetanus. These results support the idea that long-term potentiation can be demonstrated non-invasively within the human visual cortex and provide evidence that the plastic changes are localized within the secondary visual cortex.
aResearch Centre for Cognitive Neuroscience, University of Auckland, Auckland, New Zealand
bDepartment of Neuropsychology, Institute of Psychology, University of Zurich, Switzerland
cMedical Education Program, University of Idaho, Moscow, Idaho and
dDepartment of Veterinary & Comparative Anatomy, Pharmacology, & Physiology, Washington State University, Pullman, Washington, USA
Correspondence and requests for reprints to Mr Wesley Clapp, Psychology Department, City Campus, University of Auckland, Private Bag 92019, Auckland, New Zealand
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Sponsorship: Supported by grants from NIH (Grant No. R01 MH064508) and University of Auckland Research Fund (Grant No. 3604268/9353).
Received 13 September 2005; revised 28 September 2005; accepted 29 September 2005