Hippocampal Dynamics Predict Interindividual Cognitive Differences in Rats

Hok, Vincent; Chah, Ehsan; Reilly, Richard B.; O’Mara, Shane M.

doi:10.1523/jneurosci.6449-11.2012

Cited by 35 publications

(34 citation statements)

References 52 publications

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“…These findings are consistent with Barnes et al (1997) in which ensembles of CA1 pyramidal cells remapped in 6/6 old rats and 1/6 young adult rats when they were familiar with the environment. Also, McNaughton et al (1996) observed remapping in one young rat between separate recordings on a track that it had over a week of prior experience with, and Hok et al (2012) reported remapping in 2/4 middle-aged rats and 1/4 aged rats in an open field environment in which they had at least 10 days of experience.…”

Section: Discussionmentioning

confidence: 99%

Tracking the Course of Hippocampal Representations during Learning: When Is the Map Required?

2013

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Distinct ensembles of hippocampal cells can be active in numerous contexts, but specific ‘cognitive maps’ tend to be retrieved on repeat visits to the same place. During aging, the reliability of map retrieval in CA1 networks is reduced; this provides a unique opportunity to investigate correlations between inconsistent activity patterns in circuits hypothesized to enable context encoding and hippocampus-dependent learning ability. Here, CA1 pyramidal cells were recorded in six young and six old rats while memory for specific locations was probed using a place-dependent eyeblink conditioning task. Rats were conditioned twice daily for 31 days, during which a total of 8259 and 7042 cells were recorded from young and old rats, respectively. Spontaneous remapping, a change in location of the majority of place fields between two consecutive sessions in the same environment, was observed in two young rats and four old rats during this task, but only after at least 13 days of training. Under these conditions the altered network representation did not result in loss of spatial accuracy of the blink, and in fact those rats with the best place conditioning remapped the most, whereas those with the best memory in a spatial water maze task remapped the least. These results suggest that when the hippocampal representation for a particular context is weak or unstable, such as can occur in senescence, extra-hippocampal systems that mediate alternate learning strategies are more likely to dominate behavior.

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Section: Discussionmentioning

confidence: 99%

Tracking the Course of Hippocampal Representations during Learning: When Is the Map Required?

2013

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“…Statistics. No statistical methods were used to predetermine sample sizes, but our sample sizes are 508 similar to those reported for place cells in previous studies 7,14 . Statistical tests included Levene's test 509 for equality of variances, two-sample t-test assuming unequal variances, two-sample t-test assuming 510 equal variances, Pearson's correlations and χ² test.…”

mentioning

confidence: 87%

“…In order to assess the remapping events, we performed cross-correlations between the smoothed 443 firing rate maps (using a 5x5 kernel) of the sessions where the same neurons have been identified 444 based on their waveform properties 7 . To be considered as a remapping event the correlation had to 445 fall under a cut-off of r = 0.5 7,8 . 446…”

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confidence: 99%

A spatial code in the dorsal lateral geniculate nucleus

Hok

Jacob

Bordiga

et al. 2018

Preprint

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Since their discovery in the early ‘70s1, hippocampal place cells have been studied in numerous animal and human spatial memory paradigms2–4. These pyramidal cells, along with other spatially tuned types of neurons (e.g. grid cells, head direction cells), are thought to provide the mammalian brain a unique spatial signature characterizing a specific environment, and thereby a memory trace of the subject’s place5. While grid and head direction cells are found in various brain regions, only few hippocampal-related structures showing ‘place cell’-like neurons have been identified6,7, thus reinforcing the central role of the hippocampus in spatial memory. Concurrently, it is increasingly suggested that visual areas play an important role in spatial cognition as recent studies showed a clear spatial selectivity of visual cortical (V1) neurons in freely moving rodents8–10. We therefore thought to investigate, in the rat, such spatial correlates in a thalamic structure located one synapse upstream of V1, the dorsal Lateral Geniculate Nucleus (dLGN), and discovered that a substantial proportion (ca. 30%) of neurons exhibits spatio-selective activity. We found that dLGN place cells maintain their spatial selectivity in the absence of visual inputs, presumably relying on odor and locomotor inputs. We also found that dLGN place cells maintain their place selectivity across sessions in a familiar environment and that contextual modifications yield separated representations. Our results show that dLGN place cells are likely to participate in spatial cognition processes, creating as early as the thalamic stage a comprehensive representation of one given environment.

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“…For example, old rats show differences in the stability of their cognitive maps as assessed by ensemble recordings of hippocampal neurons (Barnes et al, 1997; Schimanski et al, 2013). CA1 hippocampal pyramidal cells in aged rats occasionally generate a new and distinct place cell representation for a familiar environment (Barnes et al, 1997; Schimanski et al, 2013), and these cells take significantly longer to begin to show consistent spatial firing, even in familiar environments (Hok et al, 2012). …”

Section: How Does Aging Affect Our Ability To Compute Online Spatimentioning

confidence: 99%