Encoding and Retrieval in a CA1 Microcircuit Model of the Hippocampus

Cutsuridis, Vassilis; Cobb, Stuart; Graham, Bruce

doi:10.1007/978-3-540-87559-8_25

Cited by 16 publications

(19 citation statements)

References 30 publications

(39 reference statements)

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“…Preliminary studies have been previously published in Cutsuridis et al (2007Cutsuridis et al ( , 2008a and Graham and Cutsuridis (2009). Figure 1 illustrates the simulated microcircuit model of the CA1 network.…”

Section: Introductionmentioning

confidence: 95%

Encoding and retrieval in a model of the hippocampal CA1 microcircuit

2009

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It has been proposed that the hippocampal theta rhythm (4-7 Hz) can contribute to memory formation by separating encoding (storage) and retrieval of memories into different functional half-cycles (Hasselmo et al. (2002) Neural Comput 14:793-817). We investigate, via computer simulations, the biophysical mechanisms by which storage and recall of spatio-temporal input patterns are achieved by the CA1 microcircuitry. A model of the CA1 microcircuit is presented that uses biophysical representations of the major cell types, including pyramidal (P) cells and four types of inhibitory interneurons: basket (B) cells, axo-axonic (AA) cells, bistratified (BS) cells and oriens lacunosum-moleculare (OLM) cells. Inputs to the network come from the entorhinal cortex (EC), the CA3 Schaffer collaterals and medial septum. The EC input provides the sensory information, whereas all other inputs provide context and timing information. Septal input provides timing information for phasing storage and recall. Storage is accomplished via a local STDP mediated hetero-association of the EC input pattern and the incoming CA3 input pattern on the CA1 pyramidal cell target synapses. The model simulates the timing of firing of different hippocampal cell types relative to the theta rhythm in anesthetized animals and proposes experimentally confirmed functional roles for the different classes of inhibitory interneurons in the storage and recall cycles (Klausberger et al., (2003, 2004) Nature 421:844-848, Nat Neurosci 7:41-47). Measures of recall performance of new and previously stored input patterns in the presence or absence of various inhibitory interneurons are employed to quantitatively test the performance of our model. Finally, the mean recall quality of the CA1 microcircuit is tested as the number of stored patterns is increased.

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Section: Introductionmentioning

confidence: 95%

Encoding and retrieval in a model of the hippocampal CA1 microcircuit

2009

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“…when the physical location of a reward changes). This model has been simulated with a considerable degree of physiological detail (Cutsuridis et al 2008(Cutsuridis et al , 2010Cutsuridis and Wenneckers 2009). However, the model focusses on the hippocampus and does not address the role of the cortex in these memory functions, other than the general view that it is the long term storage location for declarative memory, with the hippocampus providing intermediate term storage.…”

Section: Other Modelling Approachesmentioning

confidence: 99%

Modelling Memory and Learning Consistently from Psychology to Physiology

Coward

2010

Perception-Action Cycle

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Natural selection pressures have resulted in the physical resources of the brain being organized into modules that perform different general types of information processes. Each module is made up of submodules performing different information processes of the general type, and each submodule is made up of yet more detailed modules. At the highest level, modules correspond with major anatomical structures like the cortex, hippocampus, basal ganglia, cerebellum etc. In the cortex, for example, the more detailed modules include areas, columns, neurons, and a series of neuron substructures down to molecules. Any one memory or learning phenomenon requires many information processes performed by many different anatomical structures. However, the modular structure makes it possible to describe a memory phenomenon at a high (psychological) level in terms of the information processes performed by the major anatomical structures. The same phenomenon can be described at each level in a hierarchy of more detailed descriptions, in terms of the information processes performed by anatomical substructures. At higher levels, descriptions are approximate but can be mapped to more detailed, more precise descriptions as required down to neuron levels and below. The total information content of a high level description is small enough that it can be fully understood. Small parts of a high level phenomenon, when described at a more detailed level, also have a small enough information content to be understood. The information processes and resultant hierarchy of descriptions therefore make it possible to understand cognitive phenomena like episodic, semantic or working memory in terms of neuron processes via a series of intermediate levels of description.

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“…Theta oscillations have also been implicated in the encoding and retrieval of episodic and spatial memories (Cutsuridis, Cobb, & Graham, 2008Cutsuridis & Hasselmo, 2012;Cutsuridis & Wenneckers, 2009;Hasselmo, Bodelon, & Wyble, 2002;Jensen & Lisman, 2005;Kunec, Hasselmo, & Kopell, 2005) and disruption of them results in behavioral deficits (Winson, 1978). Theta rhythm in HF is paced by MS and diagonal band of Broca in the basal forebrain (Stewart & Fox, 1990;Winson, 1978), although several theta generators and theta dipoles seem to work independently in the hippocampus (Buzsaki, 2002;Montgomery, Betancur, & Buzsaki, 2009).…”

Section: Introductionmentioning

confidence: 97%