Comparison of population coherence of place cells in hippocampal subfields CA1 and CA3

Lee, Inah; Yoganarasimha, D.; Rao, Geeta; Knierim, James

doi:10.1038/nature02739

Cited by 403 publications

(493 citation statements)

References 25 publications

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“…Multiple theories have hypothesized that the hippocampus serves to reduce interference via a process referred to as pattern separation (Marr 1971;Shapiro and Olton 1994;McClelland et al 1995;Rolls 1996). Given its sparse pattern of activity (Barnes et al 1990;Chawla et al 2005), particular attention has been paid to the DG as a potential mediator of pattern separation (Gilbert et al 2001;Lee et al 2004;Leutgeb et al 2007;Clelland et al 2009). A failure in pattern separation may provide an alternative explanation for the deficits we observe in our ADX rats.…”

mentioning

confidence: 51%

Object/context-specific memory deficits associated with loss of hippocampal granule cells after adrenalectomy in rats

Spanswick¹,

Sutherland²

2010

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Chronic adrenalectomy (ADX) causes a gradual and selective loss of granule cells in the dentate gyrus (DG) of the rat. Here, we administered replacement corticosterone to rats beginning 10 wk after ADX. We then tested them in three discrimination tasks based on object novelty, location, or object/context association. Only during testing of the object/context association did ADX rats demonstrate deficits. These findings add to a body of evidence that the hippocampus is necessary when contextual information is important. We also confirm that memory deficits after chronic adrenalectomy are not a result of loss of corticosterone per se.Research with rats (Sutherland and McDonald 1990;Kim and Faneslow 1992;Anagnostaras et al. 2001;Lehmann et al. 2009), nonhuman primates (Machado and Bachevalier 2006;Pascalis et al. 2009), and humans (Alvarez et al. 2008;Marschner et al. 2008) shows that hippocampal damage can disrupt the ability to recall or express information about context. Furthermore, several reports suggest that the hippocampus is important for creating flexible representations of context and object associations. Studies in rats (Mumby et al. 2002;O'Brien et al. 2006) and humans (Pascalis et al. 2009) show that lesions specific to the hippocampus produce deficits in object recognition only when contextual information is altered.Within the hippocampus, the dentate gyrus (DG) is important for certain aspects of memory (Xavier et al. 1999;Garthe et al. 2009). Chronic adrenalectomy (ADX) causes a gradual and selective loss of granule cells in the DG of the rat (Sloviter et al. 1989). This loss of cells is attributed to a lack of circulating corticosterone (CORT) (Sloviter et al. 1989;Woolley et al. 1991). Behavioral deficits as a result of chronic ADX have been reported in the Morris water task (Armstrong et al. 1993;Roozendaal et al. 1998;Spanswick et al. 2007) and open-field task (Islam et al. 1995). There has been debate as to whether the deficits experienced by ADX rats are a result of lost CORT or due to the depletion of the granule cell layer itself. Conrad and Roy (1995) and McCormick et al. (1997) report that acute CORT replacement is sufficient to alleviate some of the deficits in spatial tasks associated with chronic ADX. These findings have led some to conclude that the removal of CORT is responsible for the behavioral deficits experienced by ADX rats and not the loss of granule cells per se. In direct contrast to these findings, Spanswick et al. (2007) report that administration of CORT after 6 wk of ADX does not alleviate spatial deficits in a moving-platform version of the Morris water task. Also in opposition to Conrad and Roy (1995) and McCormick et al. (1997), studies utilizing colchicine as a method to remove granule cells report spatial deficits as a result of cell loss (Sutherland et al. 1983;Xavier et al. 1999;Jeltsch et al. 2001).Here, we show using three versions of a novelty-preference task (novel object, novel place, and object/context mismatch) that lesions limited to the granule cell layer...

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confidence: 51%

Object/context-specific memory deficits associated with loss of hippocampal granule cells after adrenalectomy in rats

Spanswick¹,

Sutherland²

2010

Learn. Mem.

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“…There are many reports of place fields that rapidly reorganize (i.e., change field location and/or firing rate) when the environment changes, while other place fields persist despite changes in contextual features Lee et al, 2004;Leutgeb et al, 2004). The responsive place fields may reflect the current contextual features while the persistent fields may reflect expected contextual features.…”

Section: A Role For Place Fields In Context Discriminationmentioning

confidence: 99%

Hippocampal place cells, context, and episodic memory

2006

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ABSTRACT:Although most observers agree that the hippocampus has a critical role in learning and memory, there remains considerable debate about the precise functional contribution of the hippocampus to these processes. Two of the most influential accounts hold that the primary function of the hippocampus is to generate cognitive maps and to mediate episodic memory processes. The well-documented spatial firing patterns (place fields) of hippocampal neurons in rodents, along with the spatial learning impairments observed with hippocampal damage support the cognitive mapping hypothesis. The amnesia for personally experienced events seen in humans with hippocampal damage and the data of animal models, which show severe memory deficits associated with hippocampal lesions, support the episodic memory account. Although an extensive literature supports each of these hypotheses, a specific contribution of place cells to episodic memory has not been clearly demonstrated. Recent data from our laboratory, together with previous findings, indicate that hippocampal place fields and neuronal responses to task-relevant stimuli are highly sensitive to the context, even when the contexts are defined by abstract task demands rather than the spatial geometry of the environment. On the basis of these findings, it is proposed that place fields reflect a more general context processing function of the hippocampus. Hippocampal context representations could serve to differentiate contexts and prime the relevant memories and behaviors. Since episodic memories, by definition, include information about the time and place where the episode occurred, contextual information is a necessary prerequisite for any episodic memory. Thus, place fields contribute importantly to episodic memory as part of the needed context representations. Additionally, recent findings indicate that hippocampal neurons differentiate contexts at progressively finer levels of detail, suggesting a hierarchical coding scheme which, if combined with temporal information, could provide a means of differentiating memory episodes. V V C 2006 Wiley-Liss, Inc.

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“…In young rats, encoding in CA1 can arise independently of changes in CA3 encoding [98,99], and CA1 place cells are able to encode environment-specific information despite a lesion of CA3 [100] or suppression of CA3 output by septal inactivation [101]. Information processing in CA1 that lacks CA3 inputs relies on the direct input provided by EC layer III [100].…”

Section: Ca1mentioning

confidence: 99%

Neurocognitive aging: prior memories hinder new hippocampal encoding

Wilson

Gallagher

Eichenbaum

et al. 2006

Trends in Neurosciences

305

327

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Normal aging is often accompanied by impairments in forming new memories, and studies of aging rodents have revealed structural and functional changes to the hippocampus that might point to the mechanisms behind such memory loss. In this article, we synthesize recent neurobiological and neurophysiological findings into a model of the information-processing circuit of the aging hippocampus. The key point of the model is that small concurrent changes during aging strengthen the auto-associative network of the CA3 subregion at the cost of processing new information coming in from the entorhinal cortex. As a result of such reorganization in aged memory-impaired individuals, information that is already stored would become the dominant pattern of the hippocampus to the detriment of the ability to encode new information.

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Comparison of population coherence of place cells in hippocampal subfields CA1 and CA3

Cited by 403 publications

References 25 publications

Object/context-specific memory deficits associated with loss of hippocampal granule cells after adrenalectomy in rats

Object/context-specific memory deficits associated with loss of hippocampal granule cells after adrenalectomy in rats

Hippocampal place cells, context, and episodic memory

Neurocognitive aging: prior memories hinder new hippocampal encoding

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