Regulation of Hippocampal Information Processing By K+ Release and (K+)o Accumulation: Possible Role in Learning

Izquierdo, Iván

doi:10.1007/978-1-4684-3066-0_9

Cited by 3 publications

(1 citation statement)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These have been observed mostly in invertebrates [Hawkins et al, 19931, but also occur in the mammalian hippocampus [Izquierdo, 1973;Staubli et al, 1990; see also Hawkins et al, 19931, and will not be reviewed here.…”

Section: Introductionmentioning

confidence: 99%

Long‐term potentiation and the mechanisms of memory

Izquierdo

1993

Drug Development Research

View full text Add to dashboard Cite

Long-term potentiation (LIP) is a cellular model of the memory processes that occurs in many nerve cells, usually at glutamatergic synapses. For this reason, glutamatergic synapses being the most abundant in the brain, LTP has been widely proposed as a mechanism of memory. Recent findings support this proposal and indicate that, indeed, LTP and memory processes share many properties. The initial steps of LTP and of memory involve the activation of glutamatergic NMDA (N-methyl-D-asprtate) receptors, sensitive to AP5 (amino phosphono valerate), and are very sensitive to inhibition by GABA, (gamma amino butyric acid type A) receptor agonists. The phase that follows in the next 2 or 3 h depends on activation of protein kinase C (PKC) and is sensitive to inhibitors of this enzyme family. Like LTP, the underlying mechanism of memories persists for very long periods without the need of expression; and, like LTP, memories are readily expressed upon a reinstatement of the stimuli used in their induction, as i s the case in test sessions. The expression of LTP and the expression of memory rely on AMPA (D,L-alpha-amino hydroxy methyl isoxazolone propionate) receptors sensitive to CNQX (cyano nitro quinoxaline dione). LTP occurs in many places within the brain, including the hippocampus, amygala, medial septum, and entorhinal cortex. The drug effects on memory mentioned above are seen when the drugs are infused into these brain regions. The region(s) involved depend on the type of memory being processed. These findings support the idea that LTP underlies memory acquisition, retention, and retrieval (the latter, at least for many days after acquisition) and may provide some clues for the development of drugs to alleviate memory disorders. o 1993 Wiley-Liss, Inc.

show abstract

Section: Introductionmentioning

confidence: 99%

Long‐term potentiation and the mechanisms of memory

Izquierdo

1993

Drug Development Research

View full text Add to dashboard Cite

show abstract

Three main factors in rat shuttle behavior: Their pharmacology and sequential entry in operation during a two-way avoidance session

Izquierdo

Cavalheiro

1976

Psychopharmacology

View full text Add to dashboard Cite

The effects of eserine (0.1 mg/kg), nicotine (0.2 mg/kg), atropine (2 mg/kg), methylatropine (5 mg/kg), clonidine (0.2 mg/kg), phenoxybenzamine (10 mg/kg), apomorphine (0.5 mg/kg), and haloperidol (0.5 mg/kg), i.p., on shuttle responses to a buzzer (SBs) were studied on four different behavioral paradigms in rats: (a) D test: 50 buzzers and 25 shocks at random intervals and in random order; (b) DP test: 50 buzzers paired on all trials with shocks irrespective of the performance of SBs (Pavlovian conditioning); (c) DC test: 50 buzzers followed at a randomly variable interval by shocks unless there was an SB; (d) DPC test: 50 buzzer-shock trials omitting shocks every time there was an SB (two-way avoidance). Shock-induced drive was assumed to equally pervade all four situations; stimulus contiguity ('pairing') was present only in the DP and DPC tests; and the avoidance 'contingency' was present only in the DC and DPC paradigms. An analysis of the distribution of SB performance in control animals over the 10 successive blocks of 5 buzzers of each session revealed that the response level was similar for all tests during the first 2 blocks; that of the DC and DPC groups increased above the level of the other two from the third block on; and from the fifth block on, SB performance was higher in the DPC than in the DC group and in the DP over the D group. At all blocks the sum of SBs obtained in the D test, plus DP-D, plus DC-D, gave a value quite close to that experimentally determined in the DPC group. This was interpreted as showing that during the first 10 buzzers drive was the main (or the only) factor influencing SB performance in all groups; after the third block of 5 buzzers 'contingency' became a factor on its own; and 'pairing' assumed some control over SB behavior only from the fifth block on. Eserine depressed SBs in the D test, starting from the first block of buzzers; its effect was antagonized by atropine and by methylatropine. Clonidine depressed responding in the DP and DPC paradigms, and its effect was blocked by phenoxybenzamine. Nicotine, eserine, and apomorphine increased, and atropine, methylatropine, and haloperidol decreased SB performance in both the DC and the DPC test; the effect of the two former substances could be antagonized by any of the two anticholinergic agents, and haloperidol antagonized that of apomorphine. The possibilities are discussed of: (a) a peripheral cholinergic mechanism which inhibits drive; (b) a similar mechanism which favors operation of the 'contingency' factor; (c) a dopaminergic mechanism in 'contingency'; (d) a central adrenergic inhibitory mechanism in 'pairing'.

show abstract

Role of θ rhythm during rat shuttle behavior in four different experimental situations

Cavalheiro

1979

Behavioral and Neural Biology

View full text Add to dashboard Cite

Regulation of Hippocampal Information Processing By K+ Release and (K+)o Accumulation: Possible Role in Learning

Cited by 3 publications

References 40 publications

Long‐term potentiation and the mechanisms of memory

Long‐term potentiation and the mechanisms of memory

Three main factors in rat shuttle behavior: Their pharmacology and sequential entry in operation during a two-way avoidance session

Role of θ rhythm during rat shuttle behavior in four different experimental situations

Contact Info

Product

Resources

About