Light Responsiveness of the Suprachiasmatic Nucleus: Long-Term Multiunit and Single-Unit Recordings in Freely Moving Rats

Meijer, Johanna H.; Watanabe, Kazuto; Schaap, Jeroen; Albus, Henk; Détári, László

doi:10.1523/jneurosci.18-21-09078.1998

Cited by 186 publications

(180 citation statements)

References 43 publications

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“…Thus the GABAergic network may behave as an active filter that passes excitatory inputs during the night but cuts them off during the day. This idea is in line with the enhanced light-responsiveness of SCN neurons at night compared with day (Meijer et al 1998). Propagation of light information throughout the SCN was also indicated by spatiotemporal SCN profiles of clock gene expression (e.g., mper1) and activity markers (e.g., c-fos) (Albrecht et al 1997).…”

Section: Discussionsupporting

confidence: 70%

Circadian Modulation of GABA Function in the Rat Suprachiasmatic Nucleus: Excitatory Effects During the Night Phase

Jeu

Pennartz

2002

Journal of Neurophysiology

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de Jeu, Marcel and Cyriel Pennartz. Circadian modulation of GABA function in the rat suprachiasmatic nucleus: excitatory effects during the night phase. J Neurophysiol 87: 834 -844, 2002; 10.1152/ jn.00241.2001. Gramicidin-perforated patch-clamp recordings were made from slices of the suprachiasmatic nucleus (SCN) of adult rats to characterize the role of ␥-amino butyric acid (GABA) in the circadian timing system. During the day, activation of GABA A receptors hyperpolarized the membrane of SCN neurons. During the night, however, activation of GABA A receptors either hyperpolarized or depolarized the membrane. These night-restricted depolarizations in a large subset of SCN neurons were capable of triggering spikes and thus appeared to be excitatory. The GABA A reversal potentials of SCN neurons revealed a significant day-night difference with more depolarized GABA A reversal potentials during the night than during the day. The emergence of depolarizing GABA A -mediated responses in a subset of SCN neurons at night can be ascribed to a depolarizing shift in GABA A reversal potential. The GABA A receptor antagonist bicuculline (12.5 M) increased the spontaneous firing rate of all SCN neurons during the day, indicating that spontaneous GABA A -mediated inputs inhibited the SCN neurons during this period. The effect of bicuculline (12.5 M) on the spontaneous firing rate of SCN neurons during the night was heterogeneous due to the mixture of depolarizing and hyperpolarizing GABA A -mediated inputs during this period. We conclude that GABA uniformly acts as an inhibitory transmitter during the day but excites a large subset of SCN neurons at night. This day-night modulation of GABAergic neurotransmission provides the SCN with a time-dependent gating mechanism that may counteract propagation of excitatory signals throughout the biological clock at day but promotes it at night.

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Section: Discussionsupporting

confidence: 70%

Circadian Modulation of GABA Function in the Rat Suprachiasmatic Nucleus: Excitatory Effects During the Night Phase

Jeu

Pennartz

2002

Journal of Neurophysiology

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“…Previous studies have shown rat SCN neurons to be more active during the subjective day, when animals are predominantly asleep (Meijer et al, 1997(Meijer et al, , 1998Deboer et al, 2003) and when the sleep-promoting VLPO neurons would also be most active (Sherin et al, 1996). This profile of SCN activity in relation to VLPO activity appears to contradict our results, because we show that increased activity in SCN neurons produces an inhibition of VLPO sleep-promoting neurons.…”

Section: Discussioncontrasting

confidence: 99%

Suprachiasmatic Modulation of Noradrenaline Release in the Ventrolateral Preoptic Nucleus

Saint-Mleux¹,

Bayer²,

Eggermann³

et al. 2007

Journal of Neuroscience

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As the major brain circadian pacemaker, the suprachiasmatic nucleus (SCN) is known to influence the timing of sleep and waking. We thus investigated here the effect of SCN stimulation on neurons of the ventrolateral preoptic nucleus (VLPO) thought to be involved in promoting sleep. Using an acute in vitro preparation of the rat anterior hypothalamus/preoptic area, we found that whereas single-pulse stimulations of the SCN evoked standard fast ionotropic IPSPs and EPSPs, train stimulations unexpectedly evoked a long-lasting inhibition (LLI). Such LLIs could also be evoked in VLPO neurons by pressure application of NMDA within the SCN, indicating the specific activation of SCN neurons. This LLI was shown to result from the presynaptic facilitation of noradrenaline release, because it was suppressed in presence of yohimbine, a selective antagonist of ␣ 2 -adrenoreceptors. The LLI depended on the opening of a potassium conductance, because it was annulled at E K and could be reversed below E K . These results show that the SCN can provide an LLI of the sleep-promoting VLPO neurons that could play a role in the circadian organization of the sleep-waking cycle.

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“…1C). In keeping with this strong light trigger of the rodent endogenous circadian clock (Pittendrigh and Daan, 1976;Meijer et al, 1998), the period of vigilance was followed by a period of drowsiness (Fig. 1C).…”

Section: Diurnal Changes In Illuminance Generate Fluctuations In Basamentioning

confidence: 61%

The Adult Visual Cortex Expresses Dynamic Synaptic Plasticity That Is Driven by the Light/Dark Cycle

Tsanov

Manahan‐Vaughan²

2007

J. Neurosci.

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Experimental evidence derived from in vitro studies suggests that synaptic plasticity may be involved in information processing in the adult sensory cortex. Here, we demonstrate, for the first time, that synaptic plasticity that endures for Ͼ24 h can be elicited in the visual cortex of freely moving adult rats. Both long-term potentiation (LTP) and long-term depression (LTD) were evoked in layer 2/3 of the primary visual cortex after stimulation of the dorsal lateral geniculate nucleus. We found that synaptic plasticity within visual cortex synapses is not a static phenomenon, where a particular pattern of stimulation invariably evokes the same form of synaptic plasticity but rather fluctuates in association with diurnal luminance levels. Whereas acute (12 h) dark exposure drives intrinsic synaptic transmission to basal levels, light exposure (12 h) leads to synaptic potentiation. Furthermore, low-frequency stimulation at 3 Hz generates LTD in light-exposed animals, and LTP in dark-exposed animals, in close correlation with the time course of natural slow wave oscillations. Our data demonstrate that the adult visual cortex is in a perpetually dynamic state, where the direction of plasticity changes depends on the immediate visual experience.

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Light Responsiveness of the Suprachiasmatic Nucleus: Long-Term Multiunit and Single-Unit Recordings in Freely Moving Rats

Cited by 186 publications

References 43 publications

Circadian Modulation of GABA Function in the Rat Suprachiasmatic Nucleus: Excitatory Effects During the Night Phase

Circadian Modulation of GABA Function in the Rat Suprachiasmatic Nucleus: Excitatory Effects During the Night Phase

Suprachiasmatic Modulation of Noradrenaline Release in the Ventrolateral Preoptic Nucleus

The Adult Visual Cortex Expresses Dynamic Synaptic Plasticity That Is Driven by the Light/Dark Cycle

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