Dynamic modulation of short-term synaptic plasticity in the auditory cortex: the role of norepinephrine.
Hear Res
; 271(1-2): 26-36, 2011 Jan.
Article
em En
| MEDLINE
| ID: mdl-20816739
ABSTRACT
Norepinephrine (NE) is an important modulator of neuronal activity in the auditory cortex. Using patch-clamp recording and a pair pulse protocol on an auditory cortex slice preparation we recently demonstrated that NE affects cortical inhibition in a layer-specific manner, by decreasing apical but increasing basal inhibition onto layer II/III pyramidal cell dendrites. In the present study we used a similar protocol to investigate the dependence of noradrenergic modulation of inhibition on stimulus frequency, using 1s-long train pulses at 5, 10, and 20 Hz. The study was conducted using pharmacologically isolated inhibitory postsynaptic currents (IPSCs) evoked by electrical stimulation of axons either in layer I (LI-eIPSCs) or in layer II/III (LII/III-eIPSCs). We found that 1) LI-eIPSC display less synaptic depression than LII/III-eIPSCs at all the frequencies tested, 2) in both type of synapses depression had a presynaptic component which could be altered manipulating [Ca²+]0, 3) NE modestly altered short-term synaptic plasticity at low or intermediate (5-10 Hz) frequencies, but selectively enhanced synaptic facilitation in LI-eIPSCs while increasing synaptic depression of LII/III-eIPSCs in the latest (>250 ms) part of the response, at high stimulation frequency (20 Hz). We speculate that these mechanisms may limit the temporal window for top-down synaptic integration as well as the duration and intensity of stimulus-evoked gamma-oscillations triggered by complex auditory stimuli during alertness.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Córtex Auditivo
/
Norepinefrina
/
Plasticidade Neuronal
Limite:
Animals
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article