scholarly journals Thanks for the memories: Extending the hippocampal-diencephalic mnemonic system

1999 ◽  
Vol 22 (3) ◽  
pp. 471-479 ◽  
Author(s):  
John P. Aggleton ◽  
Malcolm W. Brown
Keyword(s):  
Prefrontal Cortex ◽  
Recognition Memory ◽  
Episodic Memory ◽  
Temporal Lobe ◽  
Thalamic Nuclei ◽  
Target Article ◽  
Anterior Thalamic Nuclei ◽  
Relationship Of ◽  
The Relationship ◽  
Key Questions

The goal of our target article was to review a number of emerging facts about the effects of limbic damage on memory in humans and animals, and about divisions within recognition memory in humans. We then argued that this information can be synthesized to produce a new view of the substrates of episodic memory. The key pathway in this system is from the hippocampus to the anterior thalamic nuclei. There seems to be a general agreement that the importance of this pathway has previously been underestimated and that it warrants further study. At the same time, a number of key questions remain. These concern the relationship of this system to another temporal-lobe/diencephalic system that contributes to recognition, and the relationship of these systems to prefrontal cortex activity.

scholarly journals Episodic memory, amnesia, and the hippocampal–anterior thalamic axis

1999 ◽  
Vol 22 (3) ◽  
pp. 425-444 ◽  
Author(s):  
John P. Aggleton ◽  
Malcolm W. Brown
Keyword(s):  
Episodic Memory ◽  
Temporal Lobe ◽  
Gene Activation ◽  
Temporal Cortex ◽  
Anterograde Amnesia ◽  
Thalamic Nuclei ◽  
Medial Dorsal ◽  
New Information ◽  
Subsequent Recall ◽  
Anterior Thalamic Nuclei

By utilizing new information from both clinical and experimental (lesion, electrophysiological, and gene-activation) studies with animals, the anatomy underlying anterograde amnesia has been reformulated. The distinction between temporal lobe and diencephalic amnesia is of limited value in that a common feature of anterograde amnesia is damage to part of an “extended hippocampal system” comprising the hippocampus, the fornix, the mamillary bodies, and the anterior thalamic nuclei. This view, which can be traced back to Delay and Brion (1969), differs from other recent models in placing critical importance on the efferents from the hippocampus via the fornix to the diencephalon. These are necessary for the encoding and, hence, the effective subsequent recall of episodic memory. An additional feature of this hippocampal–anterior thalamic axis is the presence of projections back from the diencephalon to the temporal cortex and hippocampus that also support episodic memory. In contrast, this hippocampal system is not required for tests of item recognition that primarily tax familiarity judgements. Familiarity judgements reflect an independent process that depends on a distinct system involving the perirhinal cortex of the temporal lobe and the medial dorsal nucleus of the thalamus. In the large majority of amnesic cases both the hippocampal–anterior thalamic and the perirhinal–medial dorsal thalamic systems are compromised, leading to severe deficits in both recall and recognition.

scholarly journals Hippocampal–diencephalic–cingulate networks for memory and emotion: An anatomical guide

2017 ◽  
Vol 1 ◽  
pp. 239821281772344 ◽  
Author(s):  
Emma J. Bubb ◽  
Lisa Kinnavane ◽  
John P. Aggleton
Keyword(s):  
Prefrontal Cortex ◽  
Medial Temporal Lobe ◽  
Current Knowledge ◽  
Hippocampal Formation ◽  
Retrosplenial Cortex ◽  
Thalamic Nuclei ◽  
Mammillary Bodies ◽  
Individual Site ◽  
Multi Stage ◽  
Anterior Thalamic Nuclei

This review brings together current knowledge from tract tracing studies to update and reconsider those limbic connections initially highlighted by Papez for their presumed role in emotion. These connections link hippocampal and parahippocampal regions with the mammillary bodies, the anterior thalamic nuclei, and the cingulate gyrus, all structures now strongly implicated in memory functions. An additional goal of this review is to describe the routes taken by the various connections within this network. The original descriptions of these limbic connections saw their interconnecting pathways forming a serial circuit that began and finished in the hippocampal formation. It is now clear that with the exception of the mammillary bodies, these various sites are multiply interconnected with each other, including many reciprocal connections. In addition, these same connections are topographically organised, creating further subsystems. This complex pattern of connectivity helps explain the difficulty of interpreting the functional outcome of damage to any individual site within the network. For these same reasons, Papez’s initial concept of a loop beginning and ending in the hippocampal formation needs to be seen as a much more complex system of hippocampal–diencephalic–cingulate connections. The functions of these multiple interactions might be better viewed as principally providing efferent information from the posterior medial temporal lobe. Both a subcortical diencephalic route (via the fornix) and a cortical cingulate route (via retrosplenial cortex) can be distinguished. These routes provide indirect pathways for hippocampal interactions with prefrontal cortex, with the preponderance of both sets of connections arising from the more posterior hippocampal regions. These multi-stage connections complement the direct hippocampal projections to prefrontal cortex, which principally arise from the anterior hippocampus, thereby creating longitudinal functional differences along the anterior–posterior plane of the hippocampus.

Raising the profile of the anterior thalamus

1999 ◽  
Vol 22 (3) ◽  
pp. 447-448 ◽  
Author(s):  
John C. Dalrymple-Alford ◽  
Anna M. Gifkins ◽  
Michael A. Christie
Keyword(s):  
Perirhinal Cortex ◽  
Thalamic Nuclei ◽  
Anterior Thalamus ◽  
Target Article ◽  
Anterior Thalamic Nuclei

Three questions arising from Aggleton & Brown's target article are addressed. (1) Is there any benefit to considering the effects of partial lesions of the anterior thalamic nuclei (AT)? (2) Do the AT have a separate role in the proposed extended hippocampal system? (3) Should perirhinal cortex function be restricted to familiarity judgements?

Mamillary Body Lesions in Monkeys Impair Object-in-Place Memory: Functional Unity of the Fornix-Mamillary System

1997 ◽  
Vol 9 (4) ◽  
pp. 512-521 ◽  
Author(s):  
Amanda Parker ◽  
David Gaffan
Keyword(s):  
Episodic Memory ◽  
Memory Task ◽  
Control Group ◽  
Thalamic Nuclei ◽  
Mamillary Body ◽  
Control Operation ◽  
Place Memory ◽  
Severe Impairment ◽  
Anterior Thalamic Nuclei

Six monkeys were trained preoperatively in an automated object-in-place memory task in which they learned 20 new scenes in each daily session. Three of the six monkeys then received stereotaxically guided bilateral mamillary body lesions, leaving the fornix intact, while the other three received a control operation. Postoperatively the control animals' rate of learning new scenes was unchanged, but the animals with mamillary body lesions showed a severe impairment, equal to that seen in previous experiments after fornix transection. All six animals were then given fornix transection, in addition to the existing mamillary or control operation. The control group now showed, after fornix transection, an impairment equal to that of the animals with mamillary body lesions alone. But the animals with mamillary body lesions did not show any additional impairment following fornix transection. We conclude that (1) the role of the mamillary bodies in a model of human episodic memory is as important as the role of the fornix, (2) the fornix and mamillary bodies form a single functional memory system, since the effect of lesions in both parts is no more severe than the effects of a lesion in one of the parts alone, and (3) the idea that the functional effects of fornix transection result from cholmergic deafferentation of the hippocampus receives no support from the present results; rather, they support the idea that in primates the fornix and mamillary bodies, together with connected structures, including the subiculum, mamillo-thalamic tract, anterior thalamic nuclei, and cingulate bundle, form a cortico-cortical association pathway for episodic memory.

scholarly journals The relationship between cognitive function and high-resolution diffusion tensor MRI of the cingulum bundle in multiple sclerosis

2015 ◽  
Vol 21 (14) ◽  
pp. 1794-1801 ◽  
Author(s):  
Katherine A Koenig ◽  
Ken E. Sakaie ◽  
Mark J Lowe ◽  
Jian Lin ◽  
Lael Stone ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Cognitive Function ◽  
Episodic Memory ◽  
Diffusion Tensor ◽  
Posterior Cingulate Cortex ◽  
Cognitive Testing ◽  
Information Processing Speed ◽  
Cingulum Bundle ◽  
Relationship Of ◽  
The Relationship

Background: Imaging can provide noninvasive neural markers of disease progression in multiple sclerosis (MS) that are related to behavioral and cognitive symptoms. Past work suggests that diffusion tensor imaging (DTI) provides a measure of white matter pathology, including demyelination and axonal counts. Objectives: In the current study, the authors investigate the relationship of DTI measures in the cingulum bundle to common deficits in MS, including episodic memory, working memory, and information processing speed. Methods: Fifty-seven patients with MS and 17 age- and education-matched controls underwent high-spatial resolution diffusion scans and cognitive testing. Probabilistic tracking was used to generate tracks from the posterior cingulate cortex to the entorhinal cortex. Results: Radial and axial diffusivity values were significantly different between patients and controls ( p < 0.031), and in patients bilateral diffusion measures were significantly related to measures of episodic memory and speed of processing ( p < 0.033). Conclusions: The tractography-based measures of posterior cingulum integrity reported here support further development of DTI as a viable measure of axonal integrity and cognitive function in patients with MS.

Field Independence and Recognition of Trait Names in an Incidental Learning Paradigm

1978 ◽  
Vol 47 (1) ◽  
pp. 307-311 ◽  
Author(s):  
Paul De Boeck ◽  
Willem Claeys
Keyword(s):  
Recognition Memory ◽  
Incidental Learning ◽  
Field Independence ◽  
Learning Paradigm ◽  
Field Independent ◽  
Field Dependent ◽  
Socially Relevant ◽  
Relationship Of ◽  
The Relationship ◽  
Relevant Material

Field-dependent individuals are known to be superior to field-independent individuals at recognizing socially relevant material in an incidental learning paradigm. The present study tested the hypothesis that this superiority is moderated by the target-relatedness of distractors. The stimuli were trait names. To assess recognition memory a recognition list was used with distractors differing in degrees of relatedness to the targets. Results indicate that the relationship of field-dependence to false recognition of distractor traits is moderated by the target-relatedness of the latter.

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