A Model of Spatial Map Formation in the Hippocampus of the Rat

Blum, Kenneth I.; Abbott, L. F.

doi:10.1162/neco.1996.8.1.85

Cited by 305 publications

(237 citation statements)

References 12 publications

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“…This characteristic was predicted by Blum and Abbott (1996) on the basis of the temporal asymmetry of LTP induction mechanisms (Lev y and Steward, 1983;Gustafsson et al, 1987;Lev y, 1989). Temporal asymmetry implies that, as the rat passes through two adjacent points, A and B, synapses from place cells at A onto place cells at B would be preferentially enhanced.…”

Section: Effect Of Age On Experience-dependent Place Field Plasticitymentioning

confidence: 89%

“…Temporal asymmetry implies that, as the rat passes through two adjacent points, A and B, synapses from place cells at A onto place cells at B would be preferentially enhanced. In the model of Blum and Abbott (1996), when the animal traverses a sequence of locations, asymmetric LTP causes cells at a given location to activate subsequent cells in the sequence, before the rat actually reaches their original firing locations. This causes the fields to enlarge in the direction opposite to the animal's motion.…”

Section: Effect Of Age On Experience-dependent Place Field Plasticitymentioning

confidence: 99%

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The Effect of Aging on Experience-Dependent Plasticity of Hippocampal Place Cells

et al. 1997

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The firing characteristics of 1437 CA1 pyramidal neurons were studied in relation to both spatial location and the phase of the theta rhythm in healthy young and old rats performing a simple spatial task on a rectangular track. The old rats had previously been found to be deficient on the Morris spatial learning task. Age effects on the theta rhythm per se were minimal. Theta amplitude and frequency during rapid eye movement sleep were virtually identical. During behavior, theta frequency was slightly reduced with age. In both groups, cell firing occurred at progressively earlier phases of the theta rhythm as the rat traversed the place field of the cell (i.e., there was "phase precession," as reported by others). The net phase shift did not differ between age groups. The main finding of the study was a loss of experience-dependent plasticity in the place fields of old rats. During the first lap around the track on each day, the initial sizes of the place fields were the same between ages; however, place fields of young rats, but not old, expanded significantly during the first few laps around the track in a given recording session. As the place fields expanded, the rate of change of firing with phase slowed accordingly, so that the net phase change remained constant. Thus changes in field size and phase precession are coupled. A deficit in plasticity of place fields in old rats may lead to a less accurate population code for spatial location.

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Section: Effect Of Age On Experience-dependent Place Field Plasticitymentioning

confidence: 89%

Section: Effect Of Age On Experience-dependent Place Field Plasticitymentioning

confidence: 99%

The Effect of Aging on Experience-Dependent Plasticity of Hippocampal Place Cells

et al. 1997

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“…Our choice of such a model reflects our belief that the place-cell population represents a large scale, unitary construct, the environment, rather than an agglomeration of separate, smaller-scale features of the environment such as pairwise relationships between objects (O'Keefe and Conway 1978; Hetherington and Shapiro 1997; but see Shapiro et al 1997; Wood et al 1999). In part, this view is based on the notion that place cells (especially CA3 place cells) interact with each other and are not a set of independent feature detectors (Muller et al 1991, Muller et al 1996; Blum and Abbott 1996; Mehta et al 1997; Samsonovich and McNaughton 1997). It is our contention that connections among place cells will prove to be the essential feature that allows the place-cell ensemble to be used in navigation.…”

Section: Discussionmentioning

confidence: 99%

Conjoint Control of Hippocampal Place Cell Firing by Two Visual Stimuli

Fenton

Csizmadia

Muller

2000

The Journal of General Physiology

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Changing the angular separation between two visual stimuli attached to the wall of a recording cylinder causes the firing fields of place cells to move relative to each other, as though the representation of the floor undergoes a topological distortion. The displacement of the firing field center of each cell is a vector whose length is equal to the linear displacement and whose angle indicates the direction that the field center moves in the environment. Based on the observation that neighboring fields move in similar ways, whereas widely separated fields tend to move relative to each other, we develop an empirical vector-field model that accounts for the stated effects of changing the card separation. We then go on to show that the same vector-field equation predicts additional aspects of the experimental results. In one example, we demonstrate that place cell firing fields undergo distortions of shape after the card separation is changed, as though different parts of the same field are affected by the stimulus constellation in the same fashion as fields at different locations. We conclude that the vector-field formalism reflects the organization of the place-cell representation of the environment for the current case, and through suitable modification may be very useful for describing motions of firing patterns induced by a wide variety of stimulus manipulations.

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“…Finally, mossy fiber synapses may also help to establish heteroassociative links between individual items in a sequence, such as series of places [9] (Fig. 6).…”

Section: Differential Synaptic Transmission At Mossy Fiber-pyramidal mentioning

confidence: 99%

Timing and efficacy of transmitter release at mossy fiber synapses in the hippocampal network

Bischofberger

Engel

Frotscher

et al. 2006

Pflugers Arch - Eur J Physiol

115

110

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It is widely accepted that the hippocampus plays a major role in learning and memory. The mossy fiber synapse between granule cells in the dentate gyrus and pyramidal neurons in the CA3 region is a key component of the hippocampal trisynaptic circuit. Recent work, partially based on direct presynaptic patch-clamp recordings from hippocampal mossy fiber boutons, sheds light on the mechanisms of synaptic transmission and plasticity at mossy fiber synapses. A high Na + channel density in mossy fiber boutons leads to a large amplitude of the presynaptic action potential. Together with the fast gating of presynaptic Ca 2+ channels, this generates a large and brief presynaptic Ca 2+ influx, which can trigger transmitter release with high efficiency and temporal precision. The large number of release sites, the large size of the releasable pool of vesicles, and the huge extent of presynaptic plasticity confer unique strength to this synapse, suggesting a large impact onto the CA3 pyramidal cell network under specific behavioral conditions. The characteristic properties of the hippocampal mossy fiber synapse may be important for pattern separation and information storage in the dentate gyrus-CA3 cell network.Keywords Presynaptic recording . Mossy fiber boutons . Mossy fiber synapses . Hippocampus . Autoassociative networks . Episodic memory . Synaptic efficacyThe mossy fiber synapse: a key connection in the hippocampal networkThe hippocampal formation consists of three types of principal neurons: granule cells in the dentate gyrus, CA3 pyramidal cells, and CA1 pyramidal neurons. These cells are interconnected by glutamatergic synapses, forming the classical trisynaptic circuit (Fig. 1a,b). Dentate gyrus granule cells receive excitatory glutamatergic input from layer 2 pyramidal cells of the entorhinal cortex and project to CA3 pyramidal cells. CA3 pyramidal cells project to CA1 cells, which in turn project to the subiculum and back to the entorhinal cortex [4]. In addition to this trisynaptic circuit, there is also a direct input from the entorhinal cortex to both CA3 and CA1 pyramidal cells. Furthermore, CA3 pyramidal neurons are extensively connected to each other via recurrent collateral synapses.The nonmyelinated axons of the granule cells, the socalled mossy fibers, show several structural properties that distinguish them from the other synaptic pathways [39]. They project to the CA3 region, mainly traveling within a narrow band termed "stratum lucidum." Several (∼15) large "giant" boutons (∼3-5-μm diameter) emerge from a single mossy fiber axon, either arranged in an en passant manner or attached to the main axon via a short perpendicular axonal branch [1,8,29,31] (Fig. 1c,d). A large mossy fiber bouton typically contacts only a single CA3 pyramidal neuron [21], and a mossy fiber axon contacts a given CA3 pyramidal neuron only once, as boutons are ∼150 μm apart. As the rat hippocampus contains ∼1 million granule cells

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A Model of Spatial Map Formation in the Hippocampus of the Rat

Cited by 305 publications

References 12 publications

The Effect of Aging on Experience-Dependent Plasticity of Hippocampal Place Cells

The Effect of Aging on Experience-Dependent Plasticity of Hippocampal Place Cells

Conjoint Control of Hippocampal Place Cell Firing by Two Visual Stimuli

Timing and efficacy of transmitter release at mossy fiber synapses in the hippocampal network

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