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This Article Full Text Full Text (PDF) All Versions of this Article: 574/2/457    most recent jphysiol.2006.109116v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Franchi, G. Articles by Veronesi, C. Search for Related Content PubMed PubMed Citation Articles by Franchi, G. Articles by Veronesi, C. Related Collections Neuroscience

¹ Dipartimento di Scienze Biomediche e Terapie Avanzate, Sezione di Fisiologia umana and Centro di Neuroscienze, Università di Ferrara, 44100 Ferrara, Italy

It has been proposed that abnormal vibrissae input to the motor cortex (M1) mediates short-term cortical reorganization after facial nerve lesion. To test this hypothesis, we cut first the infraorbital nerve (ION cut) and then the facial nerve (VII cut) in order to evaluate M1 reorganization without any aberrant, facial-nerve-lesion-induced sensory feedback. In each animal, M1 output was assessed in both hemispheres by mapping movements induced by intracortical microstimulation. M1 output was compared in different types of peripheral manipulations: (i) contralateral intact vibrissal pad (intact hemispheres), (ii) contralateral VII cut (VII hemispheres), (iii) contralateral ION cut (ION hemispheres), (iv) contralateral VII cut after contralateral ION cut (ION + VII hemispheres), (v) contralateral pad botulinum-toxin-injected after ION cut (ION + BTX hemispheres). Right and left hemispheres in untouched animals were the reference for normal M1 map (control hemispheres). Findings demonstrated that: (1) in ION hemispheres, the mean size of the vibrissae representation was not significantly different from those in intact and control hemispheres; (2) reorganization of the vibrissae movement representation clearly emerged only in hemispheres where the contralateral vibrissae pad had undergone motor output disconnection (VII cut hemispheres); (3) the persistent loss of vibrissae input did not change the M1 reorganization pattern during the first 48 h after motor paralysis (ION + VII cut and ION + BTX hemispheres). Thus, after motor paralysis, vibrissa input does not provide the gating signal necessary to trigger M1 reorganization.

(Received 7 March 2006; accepted after revision 9 May 2006; first published online 11 May 2006)
Corresponding author G. Franchi: Dipartimento di Scienze Biomediche e Terapie Avanzate, Sezione di Fisiologia umana, Università di Ferrara, 44100 Ferrara, Italy. Email: fhg{at}dns.unife.it