Lesions in the Dentate Hilum and CA2/CA3 Regions of the Rat Hippocampus Produce Cognitive Deficits That Correlate with Site-Specific Glial Activation

Samuel, William; Masliah, Eliezer; De, Brush; García‐Muñoz, Marianela; Patino, P.; Sj, Young; Pm, Groves

doi:10.1006/nlme.1997.3789

Cited by 11 publications

(5 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, mice lacking the vasopressin V1b receptor, which is highly expressed in CA2 neurons (Young et al, 2006), show a selective impairment in episodic memory of the temporal order of events (DeVito et al, 2009). In addition, lesions at the CA3/CA2 border impair hippocampal-dependent operant conditioning (Samuel et al, 1997). Moreover, the finding that CA2 neurons exhibit place cell firing in vivo similar to CA1 neurons (Martig and Mizumori, 2010) indicates that the distal EC inputs are likely to provide a strong excitatory drive to the CA2 neurons in awake animals, given the fact that the SC inputs to CA2 neurons recruit a large net feedforward inhibition.…”

Section: Discussionmentioning

confidence: 99%

Strong CA2 Pyramidal Neuron Synapses Define a Powerful Disynaptic Cortico-Hippocampal Loop

Chevaleyre

Siegelbaum

2010

Neuron

263

385

View full text Add to dashboard Cite

Neurons propagate information through circuits by integrating thousands of synaptic inputs to generate an action potential output. Inputs from different origins are often targeted to distinct regions of a neuron’s dendritic tree, with synapses on more distal dendrites normally having a weaker influence on cellular output compared to synapses on more proximal dendrites. Here we report that hippocampal CA2 pyramidal neurons, whose function has remained obscure for 75 years, have a reversed synaptic strength rule. Thus, CA2 neurons are strongly excited by their distal dendritic inputs from entorhinal cortex but only weakly activated by their more proximal dendritic inputs from hippocampal CA3 neurons. CA2 neurons in turn make strong excitatory synaptic contacts with CA1 neurons. In this manner CA2 neurons form the nexus of a highly plastic disynaptic circuit linking the cortical input to the hippocampus to its CA1 neuronal ouput. This circuit is likely to mediate key aspects of hippocampal-dependent spatial memory.

show abstract

Section: Discussionmentioning

confidence: 99%

Strong CA2 Pyramidal Neuron Synapses Define a Powerful Disynaptic Cortico-Hippocampal Loop

Chevaleyre

Siegelbaum

2010

Neuron

263

385

View full text Add to dashboard Cite

show abstract

“…For instance, recurrent feedback loops between the dentate gyrus granule cells, and mossy cells and pyramidal cells in the hilus, are thought to be critical for the control of information processing in the hippocampal circuit (e.g., Amaral and Witter, 1989). In fact, Samuel et al (1997) showed greater performance impairment in a complex cued discrimination operant conditioning task in rats with ibotenate damage to the dentate hilum (without significant damage to the granule cells) compared to rats with CA2/CA3 damage. These results suggest that damage to the recurrent circuitry between granule cells and hilar neurons (via damage to the latter) strongly disrupts memory processes.…”

Section: Discussionmentioning

confidence: 99%

“…In other words, even a small number of spared granule cells seems to interfere with the flow of information down through the hippocampal circuit. However, recurrent feedback loops among dentate gyrus (DG) granule cells, mossy cells, and hilar pyramidal neurons seem to perform a critical role in hippocampal information processing (Amaral and Witter, 1989); as a matter of fact, damage to this feedback system interferes with the performance of tasks that require normal hippocampal function (Samuel et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Dentate gyrus-selective colchicine lesion and disruption of performance in spatial tasks: Difficulties in ?place strategy? because of a lack of flexibility in the use of environmental cues?

1999

View full text Add to dashboard Cite

The effects of intradentate colchicine injections on the performance of tasks requiring spatial working and reference memory are controversial. Multiple‐site colchicine injections (7 μg/μl; via a drawn micropipette) throughout the dentate gyrus (DG) of rats (nine sites in each hemisphere, 0.06 μl at each site) selectively destroy about 90% of the DG granule cells, as revealed by quantitative stereological estimates; stereology also revealed minor neuronal losses in the CA4 (33%) and CA1 (23%) subfields, but lack of damage to the CA3 hippocampal subfield. Spatial reference and working memory were assessed in Morris' water maze; in the reference memory task, the rats were required to learn a single, fixed location for the platform over several days of training; in the working memory task, animals were required to learn a new platform location every day, in a matching‐to‐place procedure. Compared to sham‐operated controls, lesioned rats showed significant disruption in acquisition of the reference memory water maze task; however, the data reveal that these rats did acquire relevant information about the task, probably based on guidance and orientation strategies. In a subsequent probe test, with the platform removed, lesioned rats showed disruption in precise indexes of spatial memory (e.g., driving search towards the surroundings of the former platform location), but not in less precise indexes of spatial location. Finally, the lesioned rats showed no improvement in the match‐to‐place procedure, suggesting that their working memory for places was disrupted. Thus, although capable of acquiring relevant information about the task, possibly through guidance and/or orientation strategies, DG‐lesioned rats exhibit a marked difficulty in place strategies. This is particularly evident when these rats are required to deal with one‐trial place learning in a familiar environment, such as in the working memory version of the water maze task, which requires flexibility in the use of previously acquired information. Hippocampus 1999;9:668–681. © 1999 Wiley‐Liss, Inc.

show abstract

“…The V1b receptor is highly expressed in CA2, but is not detectable in other parts of the hippocampus [19]. In addition, lesions at the border CA3/CA2 have been found to impair hippocampal operant conditioning [102]. In order to understand how CA2 is contributing to overall hippocampal function, it is becoming evident that the hippocampal circuit may need to be re-examined.…”

Section: Resultsmentioning

confidence: 99%

Synaptic integration by different dendritic compartments of hippocampal CA1 and CA2 pyramidal neurons

Piskorowski

Chevaleyre

2011

Cell. Mol. Life Sci.

View full text Add to dashboard Cite

Pyramidal neurons have a complex dendritic arbor containing tens of thousands of synapses. In order for the somatic/axonal membrane potential to reach action potential threshold, concurrent activation of multiple excitatory synapses is required. Frequently, instead of a simple algebraic summation of synaptic potentials in the soma, different dendritic compartments contribute to the integration of multiple inputs, thus endowing the neuron with a powerful computational ability. Most pyramidal neurons share common functional properties. However, different and sometimes contrasting dendritic integration rules are also observed. In this review, we focus on the dendritic integration of two neighboring pyramidal neurons in the hippocampus: the well-characterized CA1 and the much less understood CA2. The available data reveal that the dendritic integration of these neurons is markedly different even though they are targeted by common inputs at similar locations along their dendrites. This contrasting dendritic integration results in different routing of information flow and generates different corticohippocampal loops.

show abstract

Lesions in the Dentate Hilum and CA2/CA3 Regions of the Rat Hippocampus Produce Cognitive Deficits That Correlate with Site-Specific Glial Activation

Cited by 11 publications

References 31 publications

Strong CA2 Pyramidal Neuron Synapses Define a Powerful Disynaptic Cortico-Hippocampal Loop

Strong CA2 Pyramidal Neuron Synapses Define a Powerful Disynaptic Cortico-Hippocampal Loop

Dentate gyrus-selective colchicine lesion and disruption of performance in spatial tasks: Difficulties in ?place strategy? because of a lack of flexibility in the use of environmental cues?

Synaptic integration by different dendritic compartments of hippocampal CA1 and CA2 pyramidal neurons

Contact Info

Product

Resources

About