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Linking cellular mechanisms to behavior: entorhinal persistent spiking and membrane potential oscillations may underlie path integration, grid cell firing, and episodic memory.

Hasselmo ME, Brandon MP - Neural Plast. (2008)

Bottom Line: The entorhinal cortex plays an important role in spatial memory and episodic memory functions.This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration.The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

View Article: PubMed Central - PubMed

Affiliation: Center for Memory and Brain, Department of Psychology and Program in Neuroscience, Boston University, 2 Cummington Sreet, Boston, MA 02215, USA. hasselmo@bu.edu

ABSTRACT
The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration. The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

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(a) Example of gradedpersistent firing in a layer V pyramidal cell from Egorov et al. [8]. (b) Simulation of gridcell firing based on persistent firing in cells from deep layers ofmedial entorhinal cortex.  The spikingactivity shown as black dots arises from convergent input from three neuronswith the same baseline persistent firing frequency, with phase of input neuronsinfluenced by input from different speed modulated head direction cells duringmovement (trajectory shown in gray).  (c)Simulation of grid cell firing based on membrane potential oscillations indorsal layer II stellate cells in medial entorhinal cortex.
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fig2: (a) Example of gradedpersistent firing in a layer V pyramidal cell from Egorov et al. [8]. (b) Simulation of gridcell firing based on persistent firing in cells from deep layers ofmedial entorhinal cortex. The spikingactivity shown as black dots arises from convergent input from three neuronswith the same baseline persistent firing frequency, with phase of input neuronsinfluenced by input from different speed modulated head direction cells duringmovement (trajectory shown in gray). (c)Simulation of grid cell firing based on membrane potential oscillations indorsal layer II stellate cells in medial entorhinal cortex.

Mentions: In slices, pyramidal neurons in differentlayers of entorhinal cortex demonstrate the capacity to display persistentspiking activity after a depolarizing current injection or a period ofrepetitive synaptic input [5–8]. Pyramidal neurons in layer II of medialentorhinal cortex show persistent spiking that tends to turn on and off overperiods of many seconds [5]. This cyclical persistent spiking is shown in Figure 1(a). As described below, this could underlie thespatial periodicity of grid cells. Pyramidal neurons in deep layers of entorhinal cortex can maintainspiking at different graded frequencies for many minutes [8] as shown in Figure 2(a). Thepersistent spiking appears to due to muscarinic or metabotropic glutamate activationof a calcium-sensitive nonspecific cation current [7, 9, 10]. This graded persistentfiring could allow these neurons to integrate synaptic input over extendedperiods. Persistent firing has also beenshown in layer III of lateral entorhinal cortex [6].


Linking cellular mechanisms to behavior: entorhinal persistent spiking and membrane potential oscillations may underlie path integration, grid cell firing, and episodic memory.

Hasselmo ME, Brandon MP - Neural Plast. (2008)

(a) Example of gradedpersistent firing in a layer V pyramidal cell from Egorov et al. [8]. (b) Simulation of gridcell firing based on persistent firing in cells from deep layers ofmedial entorhinal cortex.  The spikingactivity shown as black dots arises from convergent input from three neuronswith the same baseline persistent firing frequency, with phase of input neuronsinfluenced by input from different speed modulated head direction cells duringmovement (trajectory shown in gray).  (c)Simulation of grid cell firing based on membrane potential oscillations indorsal layer II stellate cells in medial entorhinal cortex.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2480478&req=5

fig2: (a) Example of gradedpersistent firing in a layer V pyramidal cell from Egorov et al. [8]. (b) Simulation of gridcell firing based on persistent firing in cells from deep layers ofmedial entorhinal cortex. The spikingactivity shown as black dots arises from convergent input from three neuronswith the same baseline persistent firing frequency, with phase of input neuronsinfluenced by input from different speed modulated head direction cells duringmovement (trajectory shown in gray). (c)Simulation of grid cell firing based on membrane potential oscillations indorsal layer II stellate cells in medial entorhinal cortex.
Mentions: In slices, pyramidal neurons in differentlayers of entorhinal cortex demonstrate the capacity to display persistentspiking activity after a depolarizing current injection or a period ofrepetitive synaptic input [5–8]. Pyramidal neurons in layer II of medialentorhinal cortex show persistent spiking that tends to turn on and off overperiods of many seconds [5]. This cyclical persistent spiking is shown in Figure 1(a). As described below, this could underlie thespatial periodicity of grid cells. Pyramidal neurons in deep layers of entorhinal cortex can maintainspiking at different graded frequencies for many minutes [8] as shown in Figure 2(a). Thepersistent spiking appears to due to muscarinic or metabotropic glutamate activationof a calcium-sensitive nonspecific cation current [7, 9, 10]. This graded persistentfiring could allow these neurons to integrate synaptic input over extendedperiods. Persistent firing has also beenshown in layer III of lateral entorhinal cortex [6].

Bottom Line: The entorhinal cortex plays an important role in spatial memory and episodic memory functions.This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration.The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

View Article: PubMed Central - PubMed

Affiliation: Center for Memory and Brain, Department of Psychology and Program in Neuroscience, Boston University, 2 Cummington Sreet, Boston, MA 02215, USA. hasselmo@bu.edu

ABSTRACT
The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration. The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

Show MeSH