Lesions of the frontal cortex, hippocampus, and intralaminar thalamic nuclei have distinct effects on remembering in rats.

Mair, Robert G.; Burk, Joshua A.; Porter, M. Christine

doi:10.1037/0735-7044.112.4.772

Cited by 101 publications

(116 citation statements)

References 58 publications

(186 reference statements)

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“…Consistent with previous findings, this study shows that ILN/LT lesions did not affect acquisition of a spatial memory task or its recent retrieval assessed 5 d after the end of acquisition (Mitchell and Dalrymple-Alford, 2005;Wolff et al, 2008) (but see Mair et al, 1998;Gibb et al, 2006). In contrast, ILN/LT lesions dramatically impaired performance during the remote memory probe trial.…”

Section: Discussionsupporting

confidence: 80%

The Intralaminar Thalamic Nuclei Contribute to Remote Spatial Memory

Lopez¹,

Wolff²,

Lecourtier³

et al. 2009

J. Neurosci.

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Recent studies have shown that the anterior (ATN) and lateral thalamic nuclei (including the intralaminar nuclei; ILN/LT) play different roles in memory processes. These nuclei have prominent direct and indirect connections with the hippocampal system and/or the prefrontal cortex and may thus participate in the time-dependent reorganization of memory traces during systems-level consolidation. We investigated whether ATN or ILN/LT lesions in rats influenced acquisition and subsequent retrieval of spatial memory in a Morris water maze. Retrieval was assessed with a probe trial after a short (5 d, recent memory) or a long (25 d, remote memory) postacquisition delay. The ATN group showed impaired acquisition compared with the Sham controls and ILN/LT groups, which did not differ during acquisition, and exhibited no preference for the target quadrant during the recent or remote memory probe trials. In contrast, probe trial performance in rats with ILN/LT lesions differed according to the age of the memory, with accurate spatial retrieval for the recent memory probe trial but impaired retrieval during the remote memory one. These findings confirm that ATN but not ILN/LT lesions disrupt the acquisition of spatial memory and provide new evidence that the ILN/LT region contributes to remote memory processing. Thus, the lateral thalamus may modulate some aspects of remote memory formation and/or retrieval during the course of systems-level consolidation.

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Section: Discussionsupporting

confidence: 80%

The Intralaminar Thalamic Nuclei Contribute to Remote Spatial Memory

Lopez¹,

Wolff²,

Lecourtier³

et al. 2009

J. Neurosci.

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“…However, mPFC lesions do make hippocampal unit place fields less stable over time and more reactive to changes in the local environment (36, 37). This result is consistent with the idea that the PFC might provide a more global representation of the spatial context (1,(38)(39)(40) that is independent of the subject's exact perspective.The present study focused on how mPFC might encode whole contextual settings and how these types of representations may differ from those of the hippocampus. Toward these ends, we recorded multiple single units using 16 tetrodes implanted into the mPFC or hippocampus while animals were switched between two distinct environments.…”

supporting

confidence: 81%

supporting

confidence: 81%

Contextual encoding by ensembles of medial prefrontal cortex neurons

Hyman

Balaguer‐Ballester

et al. 2012

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

202

199

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Contextual representations serve to guide many aspects of behavior and influence the way stimuli or actions are encoded and interpreted. The medial prefrontal cortex (mPFC), including the anterior cingulate subregion, has been implicated in contextual encoding, yet the nature of contextual representations formed by the mPFC is unclear. Using multiple single-unit tetrode recordings in rats, we found that different activity patterns emerged in mPFC ensembles when animals moved between different environmental contexts. These differences in activity patterns were significantly larger than those observed for hippocampal ensembles. Whereas ≈11% of mPFC cells consistently preferred one environment over the other across multiple exposures to the same environments, optimal decoding (prediction) of the environmental setting occurred when the activity of up to ≈50% of all mPFC neurons was taken into account. On the other hand, population activity patterns were not identical upon repeated exposures to the very same environment. This was partly because the state of mPFC ensembles seemed to systematically shift with time, such that we could sometimes predict the change in ensemble state upon later reentry into one environment according to linear extrapolation from the time-dependent shifts observed during the first exposure. We also observed that many strongly action-selective mPFC neurons exhibited a significant degree of context-dependent modulation. These results highlight potential differences in contextual encoding schemes by the mPFC and hippocampus and suggest that the mPFC forms rich contextual representations that take into account not only sensory cues but also actions and time.electrophysiological recordings | population analysis | temporal encoding M any aspects of behavior are contextually dependent. Contexts can be abstract, as in the case of human language, or can be more concrete and be defined by the constellation of spatial and sensory stimuli surrounding an individual. Contextual representations can form quickly and tend to remain stable despite local variations in perspective (1). Context can also help to inform the subject about potential changes in the meaning of stimuli and actions. The medial prefrontal cortex (mPFC) is involved in various forms of cognition that depend on spatial and contextual information, including context-based cognitive tasks (2-4), contextual fear conditioning (5), and context-induced drug relapse (6-8), and is believed to be an important node in the "context" network (1, 9-12). These functions likely depend on reciprocal interactions with the hippocampus (13, 14), an area that has a well-established role in spatial and contextual processing (15)(16)(17)(18)(19)(20). Through the connection from the CA1 region, the hippocampus has multiple profound effects on mPFC neurons (21-28), and it has been proposed that during spatial navigation the mPFC may work in concert with the hippocampus to encode goal locations and aid in route planning (29,30). However, the spatial representations ...

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“…Mair (1994) Vogt (1990). Several subsequent experimental results from this research group Mair et al, 1998;Zhang et al, 1998) have provided evidence that marked deficits in delayed match to sample task performance are attributable to lesions specifically of the ILN (paracentral, central lateral, and central medial, but not the median dorsalis nucleus). These investigators interpreted the observed memory deficits primarily as a disabling of mnemonic functions of CSPTC loops by ILN injury.…”

Section: Physiologic Evidence Of Cerebral Gating Processesmentioning

confidence: 99%

The Role of Arousal and “Gating” Systems in the Neurology of Impaired Consciousness

Schiff

Plum

2000

Journal of Clinical Neurophysiology

157

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Summary:A brief taxonomy of neurologic disorders resulting in global impairments of consciousness is presented. Particular emphasis is placed on focal injuries of subcortical structures that may produce disorders that are otherwise associated to large bilateral cortical injuries. A distinction between subcortical arousal and "gating" systems is developed. Both clinical and experimental studies are reviewed in the context of these disorders and their possible underlying mechanisms. Key Words: Awareness-Persistent vegetative state-Intralaminar thalamic nuclei-Akinetic mutism-Reticular formation.Understanding the disorders of human consciousness provides an empirical first step toward understanding mechanisms underlying human awareness. The neurologist's view of consciousness is derived from reliable observations of brain structure and function that lead to implicit hypotheses. These hypotheses represent implied models that may be examined in light of many recent advances in clinical and experimental neuroscience. Impaired consciousness of a variety of kinds may result from focal brain injuries that induce widespread functional changes. Differences in the clinical features of these human disabilities illustrate the interdependent relationships of brain mechanisms underlying arousal, gating, and expression of several specific neuropsychologic traits. In many cases, brain damage is too severe to permit meaningful recovery, as exemplified by the vegetative state. In others, transient or permanent behavioral abnormalities precipitated by focal lesions may reveal the contribution of specific brain systems to the overall conscious state. Global disorders of consciousness include stupor and coma, vegetative states, akinetic mutism, absence and partial complex seizures, hyperkinetic mutism, and others. These disturbances can be acute, and relatively brief, or may persist as protracted states. The authors explore the neurology of impaired consciousness, developing a brief taxonomy of global disorders of consciousness, and placing these neurologic diseases in the context of the underlying anatomy and physiology of arousal and "gating" systems. Definition of consciousness: A definition closely following that of James (1890) is offered for the psychological dimension of consciousness:At its least, normal human consciousness consists of a serially time-ordered, organized, restricted and reflective awareness of self and the environment. Moreover, it is an experience of graded complexity and quantity.

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Lesions of the frontal cortex, hippocampus, and intralaminar thalamic nuclei have distinct effects on remembering in rats.

Cited by 101 publications

References 58 publications

The Intralaminar Thalamic Nuclei Contribute to Remote Spatial Memory

The Intralaminar Thalamic Nuclei Contribute to Remote Spatial Memory

Contextual encoding by ensembles of medial prefrontal cortex neurons

The Role of Arousal and “Gating” Systems in the Neurology of Impaired Consciousness

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