Diurnal modulation of long-term potentiation in the hamster hippocampal slice

Raghavan, Arun; Horowitz, J. M.; Fuller, Charles A.

doi:10.1016/s0006-8993(99)01523-1

Cited by 46 publications

(48 citation statements)

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“…The present data support a diurnal modulation of hippocampal neurotransmission [2,4,7,14], and demonstrate a dynamic daytime-dependence in the spike afterpotentials and postsynaptic HVA Ca 21 currents of CA3 pyramidal neurons. Depolarization-induced excitability exhibited daytime-dependent alterations, possibly related to changes in HVA Ca 21 -amplitudes.…”

supporting

confidence: 79%

“…Some of these¯uc-tuations occur independently of light cues, the most important`zeitgeber' [4]. Diurnal rhythms have also been reported for the strength of synaptic connections within the dentate gyrus and the induction of long-term potentiation (LTP) in the CA1 region of the hippocampal formation [2,7,14], which even persist in in vitro preparations [14]. We hypothesized that the daytime-dependent modulation of hippocampal neurotransmission may depend on changes in the in¯ux of Ca 21 , which is an important element of hippocampal synaptic plasticity, of postsynaptic excitability, and of neurotransmitter release [9,10,16,17].…”

mentioning

confidence: 99%

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High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day

Kole

Koolhaas

Luiten

et al. 2001

Neuroscience Letters

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High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day Kole, MHP; Koolhaas, JM; Luiten, PGM; Fuchs, E Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractThis study tested the time-of-day dependence of the intrinsic postsynaptic properties of hippocampal CA3 pyramidal neurons. High-voltage-activated Ca 21 currents and the Ca 21 -and voltage-dependent afterhyperpolarizations were examined in slices of rat brains obtained at four distinct time periods. Just after onset of the dark phase, the steady-state amplitude of the Ca 21 current (21.24^0.11 nA) was signi®cantly greater (P , 0:03) than that of the light phase (20.84^0.06 nA). Over the entire time range, the amplitude of the Ca 21 current correlated with plasma corticosterone levels in a U-shaped function. Furthermore, depolarization-induced excitability during the dark phase exhibited an increased spike after depolarization (3.1^0.1 mV) and a slower adaptation of the ®ring frequency (146^18%). These ®ndings point to a dynamic time-of-day dependence of the CA3 neuronal properties and postsynaptic Ca 21 currents. q

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supporting

confidence: 79%

mentioning

confidence: 99%

High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day

Kole

Koolhaas

Luiten

et al. 2001

Neuroscience Letters

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“…Researchers have documented diurnal and circadian differences in long-term potentiation in the hippocampus (10,11). Additional studies have also found that excitability of CA3 neurons is regulated diurnally (12).…”

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confidence: 99%

Circadian modulation of long-term sensitization in Aplysia

Fernandez

Lyons

Levenson

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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As the mechanisms for learning and memory are elucidated, modulation of learning and memory becomes a central issue. We studied the modulation of learning and memory by investigating the circadian regulation of short-and long-term sensitization of the siphon withdrawal reflex in Aplysia. We found that Aplysia exhibited diurnal and circadian rhythms of long-term sensitization (LTS) with significantly greater LTS occurring when animals were trained and tested during the day relative to those trained and tested at night. In contrast to the modulation of LTS, short-term sensitization was not regulated by the circadian clock. Time of training rather than time of testing determined the circadian rhythm of LTS. Animals trained during the subjective day demonstrated LTS when tested during either the day or the night. Conversely, when animals were trained during the night, LTS was not observed when animals were tested either at night or during the day. Thus, the circadian rhythm of LTS is a rhythm in learning rather than a rhythm in recall. The threshold required to elicit siphon withdrawal and the duration of siphon withdrawal were not regulated by the circadian clock. These results indicate that the circadian oscillator exerts strong modulatory influences on one form of long-term memory in Aplysia.H ow organisms learn has been of interest for centuries as people seek to understand and improve learning and memory abilities. One aspect of understanding learning and memory is determining how these processes are normally modulated. What conditions modulate learning and memory, and how does regulation occur? General health, motivation, age, stress, sleep patterns, and time of day may modulate learning and memory. The circadian clock regulates many behavioral and physiological processes, making it likely that circadian modulation of learning and memory also occurs (1).Circadian modulation of learning and memory has been investigated with varied results. Some studies have indicated time of day influences memory in humans (2-4), whereas other studies have found little impact of time of day on memory (5). Researchers studying hippocampus-dependent learning found that rats trained at midday showed decreased retention compared with animals trained earlier or later (6). However, other researchers found no time-of-day effects on multiple learning tasks (7). Furthermore, two laboratories studying contextual fear conditioning in mice reported different effects of the circadian clock on learning and memory (8, 9). The issue of circadian modulation of learning and memory remains to be determined.Indirect evidence for circadian modulation of learning and memory comes from in vitro studies of long-term potentiation. Researchers have documented diurnal and circadian differences in long-term potentiation in the hippocampus (10, 11). Additional studies have also found that excitability of CA3 neurons is regulated diurnally (12). Thus, some mechanisms exist for learning and memory to be rhythmic. Experiments demonstrating that consolidation ...

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“…This time-dependent LTP finds its parallel in the hippocampus. In both hamsters and mice, LTP was elevated in slices containing hippocampal CA1 prepared during light phase but tested during dark phase [41,42]. Conversely, in hippocampal slices prepared during dark phase but tested during light phase, LTP exhibited opposing activities [42].…”

Section: Circadian Fluctuations In Clock Gene Expression and Synapticmentioning

confidence: 98%

“…In both hamsters and mice, LTP was elevated in slices containing hippocampal CA1 prepared during light phase but tested during dark phase [41,42]. Conversely, in hippocampal slices prepared during dark phase but tested during light phase, LTP exhibited opposing activities [42]. These data raise the possibility that hippocampal LTP is dependent on the time of testing; they also support the hypothesis that an independent circadian center controls the hippocampal plasticity since the possible association between the SCN and the hippocampus was abolished in vitro.…”

Section: Circadian Fluctuations In Clock Gene Expression and Synapticmentioning

confidence: 99%

What Role do Circadian Rhythms Play in Learning and Memory?

Mou¹

2016

J Neurol Neurophysiol

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Circadian rhythmicity in gene expression and physiological process has been observed both in the central nervous system and in the periphery, including the hippocampus. As a center for memory formation and storage, the hippocampus shows circadian rhythmicity in clock gene expression and synaptic plasticity. Circadian variation in performance of hippocampus-dependent memory task suggests a link between clock gene oscillation and behavioral response. Yet the discrepancy in time scale between fast information encoding during memory acquisition and much slower circadian oscillation in cellular processes casts doubt on the underlying mechanism of circadian regulation of learning and memory. This short review suggests that instead of being a modulator of learning process and memory formation, the time-of-day information itself could be integrated as a component of episodic memory for later consolidation and retrieval.

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Diurnal modulation of long-term potentiation in the hamster hippocampal slice

Cited by 46 publications

References 11 publications

High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day

High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day

Circadian modulation of long-term sensitization in Aplysia

What Role do Circadian Rhythms Play in Learning and Memory?

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