Highly transient activation of primary visual cortex (V1) for tactile object recognition in sighted following 5 days of blindfolding
Single Paper Presentation

Amir Amedi
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

Joan Camprodon
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

Lotfi Merabet
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

Felix Bermpohl
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

Erin Haligan
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

Naomi Bass-Pitskel
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

Itamar Ronen
Center for Biomedical Imaging and Department of Anatomy and Neurobiology, Boston University School of Medicine

Dae-Shik Kim
Center for Biomedical Imaging and Department of Anatomy and Neurobiology, Boston University School of Medicine

Alvaro Pascual-Leone
Center for Non-invasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA

     Abstract ID Number: 24
     Full text: Not available
     Last modified: February 28, 2006
     Presentation date: 06/20/2006 4:30 PM in Hamilton Building, McNeil Theatre
     (View Schedule)

Abstract
The occipital cortex undergoes dramatic cross-modal plasticity in the blind. This could reflect connectivity and processing, which exist also in sighted (but is inhibited to some extent by visual input), or massive reorganization and growth of new connections due to prolonged blindness. One approach to answer this question is to induce complete visual deprivation in sighted subjects. Here we studied the effects of 5 days of blindfolding on tactile object recognition task (TOR) and verbal memory task. At baseline and on Day 1, LOC / LOtv showed robust TOR activation. Retinotopic areas including V1, showed negligible activation to TOR. However, on Day 5 we found robust TOR activation in V1 with either the left or the right hand but not during low-level sensorimotor controls. This activation is dramatically reduced only hours following the removal of the blindfold, and was absent 2 days later. This clearly shows a dramatic change in the V1 pattern of activation following complete visual deprivation. The speed of these functional changes makes the establishment of new connections highly improbable. Instead, we hypothesize the existence of somatosensory inputs to V1, that become unmasked with visual deafferentation.