title: Transient synaptic silencing of developing striate cortex has persistent effects on visual function and plasticity.
abstract: Neural circuits in the cerebral cortex are shaped by experience during "critical periods" early in life. For example, visual cortex is immature at the time of eye opening and gradually develops its functional properties during a sensitive period. Very few reports have addressed the role of intrinsic neural activity in cortical maturation. Here we have exploited the bacterial enzyme botulinum neurotoxin E (BoNT/E) to produce a unilateral, reversible blockade of neural activity in rat visual cortex during the sensitive period. BoNT/E is a highly selective protease that interferes with transmitter release via cleavage of the synaptic protein SNAP-25 (synaptosomal-associated protein of 25 kDa). Unilateral, intracortical injections of BoNT/E were made at the time of eye opening and resulted in the silencing of the treated, but not contralateral, hemisphere for a period of 2 weeks. We found that visual acuity was permanently reduced in the blocked hemisphere, and the critical period for ocular dominance plasticity persisted into adulthood. Unexpectedly, these effects extended equally to the contralateral, uninjected side, demonstrating a fundamental role for interhemispheric connections in cortical maturation.
authors: Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche, 56100 Pisa, Italy. caleo@in.cnr.it
authors: Matteo
authors: M
authors: Caleo
authors: Laura
authors: L
authors: Restani
authors: Laura
authors: L
authors: Gianfranceschi
authors: Laura
authors: L
authors: Costantin
authors: Chiara
authors: C
authors: Rossi
authors: Ornella
authors: O
authors: Rossetto
authors: Cesare
authors: C
authors: Montecucco
authors: Lamberto
authors: L
authors: Maffei
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D003337:Corpus Callosum / Q000166:cytology / Q000254:growth & development / Q000502:physiology; D003423:Critical Period, Psychological; D004292:Dominance, Cerebral / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D015349:Vision, Monocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D014793:Visual Cortex / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D014795:Visual Pathways / Q000166:cytology / Q000254:growth & development / Q000502:physiology*
chemical_list: D001905:Botulinum Toxins; C096326:botulinum toxin type E