Psychopharmacology

Kumar, Ramesh; Stolerman, Ian P.; Steinberg, H

doi:10.1146/annurev.ps.21.020170.003115

Cited by 35 publications

(6 citation statements)

References 55 publications

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“…A drug such as anisomycin could act as a discriminative stimulus for state-dependent learning (26). The combination of drug and initial exposure to the novel environment could effectively provide a different environment than the novel environment alone 6 h later, when the drug has ceased to act.…”

Section: The Stability and Recall Of Existing Place Fields Is Not Affmentioning

confidence: 99%

The long-term stability of new hippocampal place fields requires new protein synthesis

Agnihotri

Hawkins

Kandel

et al. 2004

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

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The hippocampus is critical for formation of spatial memories. Hippocampal pyramidal neurons in freely behaving animals exhibit spatially selective firing patterns, which taken together form an internal representation of the environment. This representation is thought to contribute to the hippocampal spatial memory system. Behavioral long-term memories differ from short-term memories in requiring the synthesis of new proteins. Does the development of the internal hippocampal representation also require the synthesis of new proteins? We found that blocking protein synthesis in the brain of mice by 95% does not affect short-term stability of newly formed hippocampal place fields but abolishes stability in the long term. By contrast, inhibiting protein synthesis does not affect the retention and recall of previously established fields in a familiar environment, indicating that protein synthesis-dependent reconsolidation is not required for recall. Our results indicate that place fields parallel both behavioral memories and the late phase of long-term potentiation in requiring the synthesis of new proteins for consolidation.hippocampus ͉ place cells ͉ anisomycin ͉ long-term memory ͉ consolidation I n humans, explicit memory storage is concerned with memories about places, objects, and people and requires selective attention and conscious effort (1). This type of memory requires the hippocampus and associated structures in the medial temporal lobe (2). A major focus in the study of explicit memory has been on the storage of spatial information, or memory about place (3).In freely moving rodents, pyramidal cells of the CA1 region of the hippocampus exhibit a spatially selective activity pattern, firing only when the animal is in certain cell-specific locations (place fields) in the environment (4). Place fields are environmentally specific; the firing field of a place cell in one environment does not predict its field in another (5). When the animal enters a new environment, new place fields form within a matter of minutes (6, 7) and can be stable for months (8). The long-term stability of place fields implies that the representation is recalled and not created de novo each time the animal enters a familiar environment, as would be expected of elements of a spatial memory system in the hippocampus.Behavioral memories depend on the synthesis of new proteins for long-term stability. Specifically, it has been found that the initial acquisition and early retention of memory are independent of synthesis of new proteins, whereas protein synthesis during or shortly after training is required for the formation of long-term memories (9). Synaptic models of memory such as long-term potentiation (LTP) also share a similar requirement of protein synthesis (10). The most studied locus of LTP has been that of synapses onto hippocampal pyramidal CA1 cells, the same neurons acting as place cells in behaving animals (11). This makes place cells an ideal system to relate the molecular studies of memory storage to those of behavioral me...

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Section: The Stability and Recall Of Existing Place Fields Is Not Affmentioning

confidence: 99%

The long-term stability of new hippocampal place fields requires new protein synthesis

Agnihotri

Hawkins

Kandel

et al. 2004

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

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“…Firstly, it is well documented (Kumar et al, 1970) that many central nervous depressant drugs may interfere with memory establishment and it has been suggested that this may result from the impairment of (B in Figure 2 (Johnson, 1972(Johnson, , 1975b, lithium ions could prevent the formation of the interfering traces and delay the stm decay process (A in Figure 2). Johnson (1970) (Johnson,197 la,b).…”

Section: Discussionmentioning

confidence: 99%

“…Since, on the basis of many studies involving electroschock-and drug-induced modification of learning and memory (e.g. McGaugh & Madsen, 1964;Kumar, Stolerman & Steinberg, 1970), shortterm memory traces may be regarded as being largely replaced by consolidated long-term traces by 20 min after learning, these results seemed to indicate that lithium effects, if they were indeed upon memory traces of any kind, were probably not upon the shortterm type. Benowitz & Sperry (1973) therefore suggested that the lithium effect might be upon a behaviourally inactive, convert type of trace, distinct from the short-term trace, and which functioned as a necessary precursor of long-term memory; this new type of trace had first been proposed by Benowitz & Magnus (1973).…”

Section: Introductionmentioning

confidence: 96%

The Effect of Lithium Chloride on One‐trial Passive Avoidance Learning in Rats

Johnson

1976

British J Pharmacology

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1 Expression of a one-trial passive avoidance learning response in rats was examined following injections of lithium chloride or sodium chloride before and after initial training and before the first day of testing. Five tests were given at daily intervals, 24 h after training being the time of the first test. 2 Lithium given before the first day of testing impaired response expression on the first and all subsequent days of testing; the rate of extinction was unaffected. 3 Given both before and immediately after initial training, lithium impaired response expression on the first day of testing but slowed down the subsequent rate of extinction, leading eventually to improved performance on the fifth day, as compared with placebo-treated control subjects. 4 The results are interpreted in the light of the hypothesis that lithium impaired the central processing of sensory information.

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“…In addition a measure of motor activity was taken which was free of any drug-induced changes in speed of locomotion. It must, however, be remembered that changes in motor activity may be related to factors other than exploration (Kumar, Stolerman & Steinberg, 1970;Hughes, 1972), especially if the situation is a fearful one, such as the open field (Denenberg, 1969). However, fear is less important in maze exploration (Halliday, 1968) and in this respect the hole-board resembles a maze since there is no occurrence of 'freezing' and very little defaecation or urination.…”

Section: Discussionmentioning

confidence: 99%

Effects of chlorpromazine on exploration and habituation in the rat

File

1973

British J Pharmacology

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Summary The effects of chlorpromazine, 2 and 4 mg/kg, on exploration were investigated under two independent influences—food deprivation and time of day. Rats had three 3‐minute trials in a hole‐board apparatus; hole‐investigation (head‐dips) and general motor activity were recorded. On trial 1 chlorpromazine reduced exploration to half the control level, but on trial 3 it had no effect on motor activity or head‐dips. General activity habituated from trial 1 to 3 in all groups, but some of the drug groups did not show significant habituation of head‐dips, due to the low level of responding on trial 1.

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Psychopharmacology

Cited by 35 publications

References 55 publications

The long-term stability of new hippocampal place fields requires new protein synthesis

The long-term stability of new hippocampal place fields requires new protein synthesis

The Effect of Lithium Chloride on One‐trial Passive Avoidance Learning in Rats

Effects of chlorpromazine on exploration and habituation in the rat

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