The hippocampal rate code: anatomy, physiology and theory

Ahmed, Omar J.; Mehta, Mayank R.

doi:10.1016/j.tins.2009.01.009

Cited by 109 publications

(98 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These data suggest that noveltyinduced changes in CA1 activity are induced by LC inputs. The present results combined with those previously reported (5,7,37) indicate that neuromodulatory input from LC to CA3 may indirectly contribute to spatial tuning in CA1.…”

Section: Discussionsupporting

confidence: 89%

“…3 G-J). CA1 receives major inputs from CA3 pyramidal neurons via the Schaffer collaterals, and these projections are thought to govern processing for spatial information during spatial exploration (37). CA3 input is crucial for refined spatial-tuning properties of CA1 place cells (5, 7), suggesting a role for plasticity at CA3 synapses in the establishment of place fields in CA1.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Locus coeruleus input to hippocampal CA3 drives single-trial learning of a novel context

Wagatsuma

Okuyama

Sun

et al. 2017

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

216

181

View full text Add to dashboard Cite

The memory for a new episode is formed immediately upon experience and can last up to a lifetime. It has been shown that the hippocampal network plays a fundamental role in the rapid acquisition of a memory of a one-time experience, in which the novelty component of the experience promotes the prompt formation of the memory. However, it remains unclear which neural circuits convey the novelty signal to the hippocampus for the singletrial learning. Here, we show that during encoding neuromodulatory input from locus coeruleus (LC) to CA3, but not CA1 or to the dentate gyrus, is necessary to facilitate novel contextual learning. Silencing LC activity during exposure to a novel context reduced subsequent reactivation of the engram cell ensembles in CA3 neurons and in downstream CA1 upon reexposure to the same context. Calcium imaging of the cells reactivated in both novel and familiar contexts revealed that suppression of LC inputs at the time of encoding resulted in more variable place fields in CA3 neurons. These results suggest that neuromodulatory input from LC to CA3 is crucial for the formation of a persistent memory in the hippocampus.

show abstract

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Locus coeruleus input to hippocampal CA3 drives single-trial learning of a novel context

Wagatsuma

Okuyama

Sun

et al. 2017

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

216

181

View full text Add to dashboard Cite

show abstract

“…Physiological experiments in rodents and in bats (E. fuscus and Rousettus aegyptiacus) have found cells in the hippocampus and the entorhinal cortex with great selectivity for locations in space. The firing of some hippocampal pyramidal neurons, called 'place' cells, is strongly modulated by an animal's position in a given environment (Ahmed and Mehta, 2009;Ulanovsky and Moss, 2007;Ulanovsky and Moss, 2011;Wilson and McNaughton, 1993). In the entorhinal cortex, the firing of so-called 'grid' cells varies in a regular grid-like fashion in any environment (Fyhn et al, 2004;Hafting et al, 2005;Yartsev et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Spatial memory and stereotypy of flight paths by big brown bats in cluttered surroundings

Barchi

Knowles

Simmons

2013

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYThe big brown bat, Eptesicus fuscus, uses echolocation for foraging and orientation. The limited operating range of biosonar implies that bats must rely upon spatial memory in familiar spaces with dimensions larger than a few meters. Prior experiments with bats flying in obstacle arrays have revealed differences in flight and acoustic emission patterns depending on the density and spatial extent of the obstacles. Using the same method, combined with acoustic microphone array tracking, we flew big brown bats in an obstacle array that varied in density and distribution in different locations in the flight room. In the initial experiment, six bats learned individually stereotyped flight patterns as they became familiar with the space. After the first day, the repetition rate of sonar broadcasts dropped to a stable level, consistent with low-density clutter. In a second experiment, after acquiring their stable paths, each bat was released from each of two unfamiliar locations in the room. Each bat still followed the same flight path it learned originally. In a third experiment, performed 1month after the first two experiments, three of the bats were re-flown in the same configuration of obstacles; these three resumed flying in their accustomed path. The other three bats were flown in a mirror-image reconfiguration of the obstacles; these bats quickly found stable flight paths that differed from their originally learned paths. Overall, the flight patterns indicate that the bats perceive the cluttered space as a single scene through which they develop globally organized flight paths.

show abstract

“…Ϫ/Ϫ neurons also showed substantial increases in the inhibition (Ahmed and Mehta, 2009). Additional experiments are needed to decipher this puzzle.…”

Section: Glua1mentioning

confidence: 98%

“…However, these studies did not report an increase in peak firing rates. Hence, not only the net excitatory drive onto the excitatory neurons, but the precise timing of excitatory and inhibitory inputs may be crucial in determining the peak firing rates and spatial selectivity of place cells (Ahmed and Mehta, 2009).…”

Section: In the Glua1mentioning

confidence: 99%

The Effects of GluA1 Deletion on the Hippocampal Population Code for Position

Resnik

McFarland²,

Sprengel

et al. 2012

Journal of Neuroscience

View full text Add to dashboard Cite

The GluA1 subunit of AMPA receptors (AMPARs) is critical for hippocampal synaptic transmission and plasticity. Here, we measured the activity of single units from the CA1 region of the hippocampus while GluA1 knock-out (GluA1) and wild-type (WT) mice traversed a linear track. Although overall firing rates were similar, GluA1 Ϫ/Ϫ neurons were more likely to spike in bursts, but at lower burst frequencies, compared with WT neurons. GluA1 Ϫ/Ϫ neurons showed large reductions in all measures of spatial and directional selectivity compared with WT neurons. Consistent with these alterations of single-neuron properties, the accuracy of the population code for position was substantially reduced in GluA1 Ϫ/Ϫ , yet it is predicted to approach the accuracy of WT with increasing population size. The absolute representation of space, independent of movement direction, was greatly diminished in GluA1 Ϫ/Ϫ mice and is predicted to remain reduced even for larger populations. Finally, we found that the rate maps of GluA1 Ϫ/Ϫ neurons showed increased trial-by-trial variability but reduced experiential plasticity compared with the WT. These results reveal the critical contribution of GluA1-containing AMPARs to individual place cells and the hippocampal population code for space, which could explain the selective behavioral impairments observed in these mice.

show abstract

The hippocampal rate code: anatomy, physiology and theory

Cited by 109 publications

References 83 publications

Locus coeruleus input to hippocampal CA3 drives single-trial learning of a novel context

Locus coeruleus input to hippocampal CA3 drives single-trial learning of a novel context

Spatial memory and stereotypy of flight paths by big brown bats in cluttered surroundings

The Effects of GluA1 Deletion on the Hippocampal Population Code for Position

Contact Info

Product

Resources

About