Hippocampal evoked potentials and EEG changes during classical conditioning in the rat

Buzsáki, György; Grastyán, E; Tveritskaya, I. N.; Czopf, J

doi:10.1016/0013-4694(79)90033-6

Cited by 86 publications

(24 citation statements)

References 19 publications

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“…5A). The white noise-evoked responses recorded from the dorsal hippocampus are similar to unpaired tone-evoked potentials recorded from the same subjects (not shown) and to toneevoked potentials described in the rat dorsal hippocampus by Buzsáki et al (1979). There is a multiphasic response, with multi- ple negative-and positive-going potentials.…”

Section: Electrophysiological Resultssupporting

confidence: 74%

Hippocampal function during behaviorally silent associative learning: Dissociation of memory storage and expression

Talk

Gandhi

Matzel³

2002

Hippocampus

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ABSTRACT:In laboratory studies, the assessment of memory is typically associated with overt behavioral responses. Thus, it has been difficult to determine whether the enhancement of hippocampal sensoryevoked potentials that often accompany memory formation are the neurophysiological manifestation of a memory "trace" or are a secondary product of the behavioral expression of the memory. We addressed this issue by examining changes in evoked hippocampal field potentials during sensory preconditioning, a form of behaviorally silent relational learning that requires an intact hippocampus for execution. Rats were exposed to presentations of a white noise (S1) that terminated with a tone (S2). These pairings of ostensibly "neutral" stimuli supported no change in the behavior elicited by the noise. However, if the tone was subsequently paired with mild footshock (US), suppression of ongoing licking behavior (indicative of fear) was elicited by the noise, indicating that the animal had associated the noise with tone (S1-S2), and had represented the noisetone-shock (S1-S2-US) relationship. Pre-training neurotoxic lesions of the hippocampus had no effect on conditioned suppression to tone after tone-shock (S2-US) pairings, but disrupted the expression of continued suppression to noise (S1) after tone-shock pairings. In a second experiment, sensory-evoked field potentials in the dorsal hippocampus were recorded with extracellular electrodes. No changes in the hippocampal response evoked by white noise were observed after pairings of noise and tone, i.e., no evidence for a memory trace could be detected. In contrast, after tone was paired with footshock, two short-latency negative potentials within the noise-evoked field response increased in amplitude, a response often presumed to reflect a neurophysiological correlate of memory storage. In total, these results suggest that although the hippocampus critically contributes to the processing of a behaviorally silent associative memory, there may be no role for changes in the amplitude of hippocampal sensory-evoked field potentials in storing representations of the relationships between sensory experiences. Hippocampus 2002;12:648-656.

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Section: Electrophysiological Resultssupporting

confidence: 74%

Hippocampal function during behaviorally silent associative learning: Dissociation of memory storage and expression

Talk

Gandhi

Matzel³

2002

Hippocampus

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“…In our experiments we did not observe a clear correlation between the rat's movement and the P300. It has been demonstrated that theta rhythm in behaving rats can be operantly conditioned (Fantie and Nakajima, 1987) and phase-locked by sensory stimulations (Bufio et al, 1978;Buzsiki et al, 1979Buzsiki et al, , 1982. Berry and Thompson (1978) found in rabbits a linear correlation between the rate of conditioning of the nictitating membrane response and the pretrial occurrence of theta rhythm.…”

Section: Difference (R-i)mentioning

confidence: 97%

Task-relevant late positive component in rats: Is it related to hippocampal theta rhythm?

Brankačk

Seidenbecher²,

Müller‐Gärtner

1996

Hippocampus

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“…Although the hippocampus is usually associated with consolidation of experiences into long-term memory, presentations of brief WM stimuli are known to induce resetting of the phase of theta in rodent dentate and medial septal areas (22). Phase reset of theta is seen also in recordings from cats during the acquisition of reference memory (23,24) and in rats during the initial sessions of a classical conditioning task (25). We hypothesized that phase reset may provide a unique window of opportunity for detection and characterization of hippocampal theta in humans.…”

mentioning

confidence: 96%

Theta oscillations index human hippocampal activation during a working memory task

Tesche

Karhu

2000

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

444

267

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Working memory (WM) is the ability to retain and associate information over brief time intervals. Functional imaging studies demonstrate that WM is mediated by a distributed network including frontal and posterior cortices, hippocampus, and cerebellum. In rodents, the presentation of stimuli in a WM task is followed by a reset of the phase of hippocampal theta. In this paper we report the observation of a similar phenomenon in normal human subjects. Neuromagnetic responses were recorded during presentation of a set of digits and a subsequent probe of the retained items. All stimuli were presented with a fixed temporal pattern. We observed phase reset of Ϸ7 Hz theta in left hippocampus Ϸ120 ms after probe stimuli, whereas reset of theta in right hippocampus was visible Ϸ80 ms prior to these anticipated stimuli. The duration of stimulus-locked theta increased with memory load, with a limiting value of Ϸ600 ms for 5-7 retained items. We suggest that, as in rats, stimulus-locked theta may index involvement of human hippocampal networks in the cognitive processing of sensory input. The anticipatory phase reset of theta indicates involvement of hippocampus in right hemisphere and cerebellar timing networks. Hippocampal structures are essential for orientation to perturbations in the sensory scene, a function that requires use of a context established by a constellation of stimuli. We suggest that the initiation and maintenance of stimulus-locked hippocampal theta observed here may facilitate processing of potentially salient and͞or novel input with respect to a context established by the contents of WM.

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Hippocampal evoked potentials and EEG changes during classical conditioning in the rat

Cited by 86 publications

References 19 publications

Hippocampal function during behaviorally silent associative learning: Dissociation of memory storage and expression

Hippocampal function during behaviorally silent associative learning: Dissociation of memory storage and expression

Task-relevant late positive component in rats: Is it related to hippocampal theta rhythm?

Theta oscillations index human hippocampal activation during a working memory task

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