Long-lasting potentiation of synaptic transmission in the dentate area of the anaesthetized rabbit following stimulation of the perforant path.
Timothy V. P. Bliss,T. Lømo +1 more
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The after‐effects of repetitive stimulation of the perforant path fibres to the dentate area of the hippocampal formation have been examined with extracellular micro‐electrodes in rabbits anaesthetized with urethane.Abstract:
1. The after-effects of repetitive stimulation of the perforant path fibres to the dentate area of the hippocampal formation have been examined with extracellular micro-electrodes in rabbits anaesthetized with urethane.2. In fifteen out of eighteen rabbits the population response recorded from granule cells in the dentate area to single perforant path volleys was potentiated for periods ranging from 30 min to 10 hr after one or more conditioning trains at 10-20/sec for 10-15 sec, or 100/sec for 3-4 sec.3. The population response was analysed in terms of three parameters: the amplitude of the population excitatory post-synaptic potential (e.p.s.p.), signalling the depolarization of the granule cells, and the amplitude and latency of the population spike, signalling the discharge of the granule cells.4. All three parameters were potentiated in 29% of the experiments; in other experiments in which long term changes occurred, potentiation was confined to one or two of the three parameters. A reduction in the latency of the population spike was the commonest sign of potentiation, occurring in 57% of all experiments. The amplitude of the population e.p.s.p. was increased in 43%, and of the population spike in 40%, of all experiments.5. During conditioning at 10-20/sec there was massive potentiation of the population spike (;frequency potentiation'). The spike was suppressed during stimulation at 100/sec. Both frequencies produced long-term potentiation.6. The results suggest that two independent mechanisms are responsible for long-lasting potentiation: (a) an increase in the efficiency of synaptic transmission at the perforant path synapses; (b) an increase in the excitability of the granule cell population.read more
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A synaptic model of memory: long-term potentiation in the hippocampus
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Emotion Circuits in the Brain
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Memory and the hippocampus: A synthesis from findings with rats, monkeys, and humans.
TL;DR: The role of the hippocampus is considered, which is needed temporarily to bind together distributed sites in neocortex that together represent a whole memory.
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Synaptic Modifications in Cultured Hippocampal Neurons: Dependence on Spike Timing, Synaptic Strength, and Postsynaptic Cell Type
Guo-Qiang Bi,Mu-ming Poo +1 more
TL;DR: The results underscore the importance of precise spike timing, synaptic strength, and postsynaptic cell type in the activity-induced modification of central synapses and suggest that Hebb’s rule may need to incorporate a quantitative consideration of spike timing that reflects the narrow and asymmetric window for the induction of synaptic modification.
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Why there are complementary learning systems in the hippocampus and neocortex: insights from the successes and failures of connectionist models of learning and memory.
TL;DR: The account presented here suggests that memories are first stored via synaptic changes in the hippocampal system, that these changes support reinstatement of recent memories in the neocortex, that neocortical synapses change a little on each reinstatement, and that remote memory is based on accumulated neocorticals changes.
References
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Wilfrid Rall,Gordon M. Shepherd +1 more
TL;DR: A computational model was developed that could reconstruct the distribution of electric potential as a function of two variables, time and depth in the bulbar layers, following a synchronous antidromic volley in the lateral olfactory tract.
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Origin and termination of the hippocampal perforant path in the rat studied by silver impregnation.
A Hjorth-Simonsen,Bernard Jeune +1 more
TL;DR: A detailed study of the origin and termination of the so‐called perforant path of the hippocampal region has been made in the rat, finding the origin to be in the medial part of the entorhinal area, from the most dorsal to the most ventral levels.
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Unit analysis of hippocampal population spikes
TL;DR: It is concluded that over a wide range the height of the population spike is an increasing function of the number of discharging cells and can thus be used as a measure of the extent to which an afferent volley discharges a cell population.
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Patterns of activation in a monosynaptic cortical pathway : the perforant path input to the dentate area of the hippocampal formation
TL;DR: In rabbits, anaesthetized with urethane/chloralose, stimulation with tungsten microelectrodes was employed to initiate a volley in the perforant path fibres which made en-passage contacts with the apical dendrites of dentate granule cells, indicating an active synaptic sink restricted to the middle third of the dendritic region.