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Titolo:
Role of inhibition in cortical reorganization of the adult raccoon revealed by microiontophoretic blockade of GABA(A) receptors
Autore:
Tremere, L; Hicks, TP; Rasmusson, DD;
Indirizzi:
Dalhousie Univ, Dept Physiol & Biophys, Halifax, NS B3H 4H7, Canada Dalhousie Univ Halifax NS Canada B3H 4H7 hys, Halifax, NS B3H 4H7, Canada Natl Res Council Canada, Inst Biol Sci, Ottawa, ON K1A 0R6, Canada Natl Res Council Canada Ottawa ON Canada K1A 0R6 tawa, ON K1A 0R6, Canada
Titolo Testata:
JOURNAL OF NEUROPHYSIOLOGY
fascicolo: 1, volume: 86, anno: 2001,
pagine: 94 - 103
SICI:
0022-3077(200107)86:1<94:ROIICR>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
PRIMARY SOMATOSENSORY CORTEX; NEONATAL FORELIMB REMOVAL; ACTIVITY-DEPENDENT REGULATION; GLUTAMIC-ACID DECARBOXYLASE; PARTIAL DIGIT DENERVATION; LATERAL THALAMIC NUCLEUS; BARREL CORTEX; PERIPHERAL DENERVATION; GAD-IMMUNOREACTIVITY; TACTILE STIMULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
52
Recensione:
Indirizzi per estratti:
Indirizzo: Rasmusson, DD Dalhousie Univ, Dept Physiol & Biophys, Halifax, NS B3H 4H7,Canada Dalhousie Univ Halifax NS Canada B3H 4H7 NS B3H 4H7, Canada
Citazione:
L. Tremere et al., "Role of inhibition in cortical reorganization of the adult raccoon revealed by microiontophoretic blockade of GABA(A) receptors", J NEUROPHYS, 86(1), 2001, pp. 94-103

Abstract

Cortical reorganization was induced by amputation of the 4th digit in 11 adult raccoons. Animals were studied at various intervals, ranging from 2 to37 wk, after amputation. Recordings were made from a total of 129 neurons in the deafferented cortical region using multibarrel micropipettes. Several types of receptive fields were described in reorganized cortex: restricted fields were similar in size to the normal receptive fields in nonamputated animals; multi-regional fields included sensitive regions on both adjacent digits and/or the underlying palm and were either continuous over the entire field or consisted of split fields. The proportion of neurons with restricted fields increased with time after amputation and was greater than previously found in subcortical regions. A GABA(A) receptor antagonist (bicuculline methiodide), glutamate, and GABA were administered iontophoretically to these neurons while determining their receptive fields and thresholds. Bicuculline administration resulted in expansion of the receptive field in 60% of the 93 neurons with cutaneous fields. In most cases (33 neurons) thisconsisted of a simple expansion around the borders of the predrug receptive field, and the average expansion (426%) was not different from that seen in nonamputated animals. In some neurons (n = 4), bicuculline produced an expansion from one digit onto the adjacent palm or another digit, an effect never seen in control animals. Bicuculline also changed the split fields ofseven neurons into continuous fields by exposing a responsive region between the split fields. Finally, bicuculline changed the internal receptive field organization of 10 neurons by revealing subfields with reduced thresholds. In contrast to the situation in nonamputated animals, iontophoretic administration of glutamate also produced receptive field expansion in some neurons (n = 6), but the size and/or shape of the change was different from that produced by bicuculline, indicating that the effects of bicuculline were not due to an overall facilitation of neuronal activity. These results are consistent with the hypotheses that an important component of long-term cortical reorganization is the gradual reduction in effective receptive field size and that intracortical inhibitory networks are partially responsiblefor these changes.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/04/20 alle ore 22:53:40