Long-term depression of horizontal connections in rat motor cortex.
Eur J Neurosci
; 8(4): 658-65, 1996 Apr.
Article
em En
| MEDLINE
| ID: mdl-9081617
ABSTRACT
The possibility for long-term depression (LTD) of synaptic transmission in layer II/III horizontal connections within motor cortex was investigated using field potentials and intracellular recordings in rat brain slices. The LTD was induced by low-frequency stimulation at 2 Hz for 10 min in sites displaced horizontally by 0.5 mm from the stimulating electrode. Response amplitude measured 25-30 min after 2 Hz stimulation ended was 79% of baseline values (n = 13) at half maximal stimulation and 59% when 2 Hz stimulus intensity was doubled (n = 10). In 13/15 tested cases LTD in horizontal connections was specific to the activated pathway. Intracellular recordings from six neurons confirmed synaptic character of response depression. Horizontal connections in which LTD was induced retained the capability of increasing synaptic strength. Long-term potentiation could be induced in previously depressed pathways by simultaneous theta burst stimulation of two converging horizontal inputs combined with transient local application of GABA(A) receptor antagonist bicuculline methiodide (mean increase 45 +/- 8% n = 6) or by simultaneous theta burst stimulation of converging horizontal and vertical inputs (mean change 26 +/- 6%, n = 5). These data demonstrate that activity-dependent mechanisms may regulate bidirectionally the effectiveness of horizontal synaptic coupling between cortical neurons, thus forming a potential mechanism for plasticity of cortical connections and the representation patterns they support.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Potenciação de Longa Duração
/
Córtex Motor
Limite:
Animals
Idioma:
En
Revista:
Eur J Neurosci
Ano de publicação:
1996
Tipo de documento:
Article