Multiple retention deficits at periodic intervals after active and passive avoidance learning

Holloway, Frank; Wansley, Richard A.

doi:10.1016/s0091-6773(73)80164-6

Cited by 126 publications

(64 citation statements)

References 10 publications

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“…During learning and the formation of memory, information may be stored in a time-stamped manner such that peak recall may occur in 24-h intervals after training or the time of day may become a contextual component of learning (29)(30)(31)(32). The rhythm of LTS is a case of modulation by the circadian clock and not a contextual time-stamping event, because animals trained in the subjective day exhibited LTS when tested either in the subjective day or night.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…Several studies have already demonstrated that performance on learning tasks is optimal at 24-h intervals from the time of training and is significantly worse at noncircadian intervals (23)(24)(25)(26). We were, by contrast, interested in evaluating whether loss of rhythms would lead to more general cognitive impairments in our neurologically intact arrhythmic animals regardless of time of day.…”

mentioning

confidence: 99%

Hippocampal-dependent learning requires a functional circadian system

Ruby

Hwang²,

Wessells³

et al. 2008

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

203

219

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Decades of studies have shown that eliminating circadian rhythms of mammals does not compromise their health or longevity in the laboratory in any obvious way. These observations have raised questions about the functional significance of the mammalian circadian system, but have been difficult to address for lack of an appropriate animal model. Surgical ablation of the suprachiasmatic nucleus (SCN) and clock gene knockouts eliminate rhythms, but also damage adjacent brain regions or cause developmental effects that may impair cognitive or other physiological functions. We developed a method that avoids these problems and eliminates rhythms by noninvasive means in Siberian hamsters (Phodopus sungorus). The present study evaluated cognitive function in arrhythmic animals by using a hippocampal-dependent learning task. Control hamsters exhibited normal circadian modulation of performance in a delayed novel-object recognition task. By contrast, arrhythmic animals could not discriminate a novel object from a familiar one only 20 or 60 min after training. Memory performance was not related to prior sleep history as sleep manipulations had no effect on performance. The GABA antagonist pentylenetetrazol restored learning without restoring circadian rhythms. We conclude that the circadian system is involved in memory function in a manner that is independent of sleep. Circadian influence on learning may be exerted via cyclic GABA output from the SCN to target sites involved in learning. Arrhythmic hamsters may have failed to perform this task because of chronic inhibitory signaling from the SCN that interfered with the plastic mechanisms that encode learning in the hippocampus.GABA ͉ hippocampus ͉ memory ͉ sleep ͉ suprachiasmatic nucleus

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“…Several authors have shown that the level of performance waxes and wanes, more or less regularly, as a function of the length of the training-to-test interval (TIl) (Cherkin, 1971;Holloway &. Wansley, 1973;Huppert &.…”

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confidence: 99%

Differential effects of several retrieval cues over time: Evidence for time-dependent reorganization of memory

Gisquet-Verrier¹,

Dekeyne²,

Alexinsky³

1989

Animal Learning & Behavior

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The retention performance following partial training (15 trials) of a brightness-discrimination avoidance task has been shown to fluctuate over time, with a drop in performance 1 h after training (Kamin effect), a long-term spontaneous improvement (LTSl) after 3 days, and long-term spontaneous forgetting after 21 days. The purpose of this paper was to determine ifthese time-dependent modulations of retention performance reflect time-dependent modifications in the organization of the attributes that constitute the memory trace. We studied the relative effectiveness of several pretest cuings on retention performance when they were delivered just before a retention test occurring 1 h, 3 days, or 21 days following initial training. Some cuing treatments were related to a particular training event (conditioned or unconditioned stimulus, experimental context). Compound cuings, composed of two or more training events, were also studied to test a possible additive effect between retrieval cues. To demonstrate time-dependent modifications in the memory trace, a differential effectiveness over time was expected for at least some retrieval cues. The results show that cuing may compensate for performance deficits (1 h or 21 days), but does not further enhance performance when spontaneously improved (3 days). No detectable additive effects of retrieval cues were obtained. However, these results provide information that suggests a time-dependent effectiveness for some cuing treatments. In the last experiment, we investigated this possibility by studying the effects of each of these treatments when delivered after either a J-h or a 21-day retention interval. The results confirm a time-dependent decrease in effectiveness of a pretest exposure to the CS and an increase in effectiveness over time of a pretest exposure to the experimental context or to a well-ordered sequence of events. Such differential retrievability of a partially learned episode according to both the nature of the cues and the length of the retention interval suggests a time-dependent reorganization of memory attributes.

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Multiple retention deficits at periodic intervals after active and passive avoidance learning

Cited by 126 publications

References 10 publications

Circadian modulation of long-term sensitization in Aplysia

Circadian modulation of long-term sensitization in Aplysia

Hippocampal-dependent learning requires a functional circadian system

Differential effects of several retrieval cues over time: Evidence for time-dependent reorganization of memory

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