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Gerstner, Wulfram; Abbott, L. F.

doi:10.1023/a:1008820728122

Cited by 99 publications

(26 citation statements)

References 35 publications

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“…Just as well the particular cells that fire on a certain pass might indicate where the rat will wind up after exiting the field. These possibilities are in line with a vector field model of hippocampal mapping (24) in which the firing of place cells during locomotion is biased locally in that direction that eventually will take the rat to a goal. Provision for multiple goals in a single environment is made by supposing that different place cells with different local directional biases are turned on or off by gain control depending on which potential goal is current.…”

Section: Discussionsupporting

confidence: 60%

Place cell discharge is extremely variable during individual passes of the rat through the firing field

Fenton

Muller

1998

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

262

290

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The idea that the rat hippocampus stores a map of space is based on the existence of ''place cells'' that show ''location-specific'' firing. The discharge of place cells is confined with remarkable precision to a cell-specific part of the environment called the cell's ''firing field.'' We demonstrate here that firing is not nearly as reliable in the time domain as in the positional domain. Discharge during passes through the firing field was compared with a model with Poisson variance of the location-specific firing determined by the time-averaged positional firing rate distribution. Place cells characteristically fire too little or too much compared with expectations from the random model. This fundamental property of place cells is referred to as ''excess firing variance'' and has three main implications: (i) Place cell discharge is not only driven by the summation of many small, asynchronous excitatory synaptic inputs. (ii) Place cell discharge may encode a signal in addition to the current head location. (iii) The excess firing variance helps explain why the errors in computing the rat's position from the simultaneous activity of many place cells are large.How do rodents solve difficult spatial problems? On behavioral grounds, it is believed that rats (and mice) can form map-like representations of their surroundings. Once such a representation is formed, the rat can use it to navigate because the representation contains information about the overall layout or geometry of the surroundings (1-3). Given that a spatial map exists, it is natural to ask how it is organized in the nervous system. That is, where is the map located and how does it operate?Our current understanding of spatial maps is based on the discovery of hippocampal place cells 25 years ago (4). It was observed that individual neurons in the hippocampus (pyramidal cells of CA3 and CA1) (5) show ''location-specific'' firing. A given place cell discharges rapidly only when a rat's head is in a certain part of the environment. Outside this ''firing field'' region, the cell rarely discharges (Fig. 1A). The precise confinement of discharge to firing fields at once suggested that the hippocampus is a key component of the map and that mapping information is in part positional information. In this view, the rat's current location is signaled by the conjoint firing of a set of place cells. As the rat moves, its head leaves the field of some cells and enters the field of others, so that the across-cell firing pattern changes in a characteristic way. It thus is presumed that the rat's head position can be accurately calculated if the current across-cell discharge pattern is known (6, 7).This appealing picture is predicated on a tacit assumptionthat in addition to firing only when the head is in the firing field, that a place cell fires in much the same way each time the head goes through the field along much the same path. It is not uncommon, however, for a robust place cell to be silent as the rat's head passes through the center of its firing fie...

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Section: Discussionsupporting

confidence: 60%

Place cell discharge is extremely variable during individual passes of the rat through the firing field

Fenton

Muller

1998

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

262

290

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“…Despite these limitations, there are ways in which place cells might contribute path planning, albeit in a manner different from PL͞IL cells. For example, recent computational studies suggest that they may permit retrieval of previously encoded efficient paths (37)(38)(39)(40), or even finding optimal new paths to any goal location in a familiar environment (41,42). Thus, if the hippocampus encodes goal locations, it might use this information in a different way compared with the prefrontal cortex.…”

Section: Discussionmentioning

confidence: 99%

Coding for spatial goals in the prelimbic/infralimbic area of the rat frontal cortex

Hok

Save

Lenck-Santini

et al. 2005

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

223

176

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Finding one's way in space requires a distributed neural network to support accurate spatial navigation. In the rat, this network likely includes the hippocampus and its place cells. Although such cells allow the organism to locate itself in the environment, an additional mechanism is required to specify the animal's goal. Here, we show that firing activity of neurons in medial prefrontal cortex (mPFC) reflects the motivational salience of places. We recorded mPFC neurons from rats performing a place navigation task, and found that a substantial proportion of cells in the prelimbic͞infralimbic area had place fields. A much smaller proportion of cells with such properties was found in the dorsal anterior cingulate area. Furthermore, the distribution of place fields in prelimbic͞infralimbic cells was not homogeneous: goal locations were overrepresented. Because such locations were spatially dissociated from rewards, we suggest that mPFC neurons might be responsible for encoding the rat's goals, a process necessary for path planning.goal coding ͉ place navigation ͉ unit recording

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“…It has, therefore, been supposed that STDP is a suitable learning rule for sequence learning, because synapses are potentiated by causal pre-and postsynaptic spike pairing. For example, in a model of navigational map formation, synapses between hippocampal place cells being subject to an asymmetric STDP rule are modified during random exploration, and then place cell activity indicates the direction from any location to a fixed destination (Gerstner and Abbott 1997). Spatial tasks with multiple destinations have also been considered in terms of navigational map formation (Wagatsuma and Yamaguchi 2007).…”

Section: Introductionmentioning

confidence: 99%

LTD windows of the STDP learning rule and synaptic connections having a large transmission delay enable robust sequence learning amid background noise

Hayashi

Igarashi

2009

Cogn Neurodyn

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Spike-timing-dependent synaptic plasticity (STDP) is a simple and effective learning rule for sequence learning. However, synapses being subject to STDP rules are readily influenced in noisy circumstances because synaptic conductances are modified by pre- and postsynaptic spikes elicited within a few tens of milliseconds, regardless of whether those spikes convey information or not. Noisy firing existing everywhere in the brain may induce irrelevant enhancement of synaptic connections through STDP rules and would result in uncertain memory encoding and obscure memory patterns. We will here show that the LTD windows of the STDP rules enable robust sequence learning amid background noise in cooperation with a large signal transmission delay between neurons and a theta rhythm, using a network model of the entorhinal cortex layer II with entorhinal-hippocampal loop connections. The important element of the present model for robust sequence learning amid background noise is the symmetric STDP rule having LTD windows on both sides of the LTP window, in addition to the loop connections having a large signal transmission delay and the theta rhythm pacing activities of stellate cells. Above all, the LTD window in the range of positive spike-timing is important to prevent influences of noise with the progress of sequence learning.

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Untitled

Cited by 99 publications

References 35 publications

Place cell discharge is extremely variable during individual passes of the rat through the firing field

Place cell discharge is extremely variable during individual passes of the rat through the firing field

Coding for spatial goals in the prelimbic/infralimbic area of the rat frontal cortex

LTD windows of the STDP learning rule and synaptic connections having a large transmission delay enable robust sequence learning amid background noise

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