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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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Model of episodic encodingand retrieval of trajectories.  Top:Schematic representation of connectivity between grid cells, place cells, andhead direction (HD) cells.  Bottom: exampleof trajectory retrieval activity in each region.  Trajectory experienced during encoding isshown in gray.  (a) The location coded bythe oscillation phase of entorhinal grid cell membrane potential is plotted asa dashed line that follows the actual trajectory in gray.  Grid cell phase is put through the inversehead direction transformation to obtain coded location.  Phase shifts are driven by retrieved headdirection until next place cell is activated, then phase moves in new directiondependent on next active head direction cell. (b) Sequentially activated place cell representations are shown as opencircles.  (c) Each place cell activates acorresponding head direction representation, with direction shown as a short,straight, black line.  This drives thenext period of update of the grid cell phase.
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fig6: Model of episodic encodingand retrieval of trajectories. Top:Schematic representation of connectivity between grid cells, place cells, andhead direction (HD) cells. Bottom: exampleof trajectory retrieval activity in each region. Trajectory experienced during encoding isshown in gray. (a) The location coded bythe oscillation phase of entorhinal grid cell membrane potential is plotted asa dashed line that follows the actual trajectory in gray. Grid cell phase is put through the inversehead direction transformation to obtain coded location. Phase shifts are driven by retrieved headdirection until next place cell is activated, then phase moves in new directiondependent on next active head direction cell. (b) Sequentially activated place cell representations are shown as opencircles. (c) Each place cell activates acorresponding head direction representation, with direction shown as a short,straight, black line. This drives thenext period of update of the grid cell phase.

Mentions: Theinteraction of head direction cells and grid cells described here provides apotential mechanism for episodic memory involving the storage of trajectoriesthrough space and time [57]. As shown in Figure 6, thismodel uses a functional loop that encodes and retrieves trajectories via threestages: (1)head direction cells h(t) update grid cells, (2) grid cells g(t) update place cells, and (3) place cells p(t) activate associated head directionactivity [57]. This model is consistentwith the anatomical connectivity (seeFigure 6). Thehead direction cells could update grid cells via projections from thepostsubiculum (dorsal presubiculum) to the medial entorhinal cortex [58–60], causing updating of persistent firing as described above, orinfluencing the phase of membrane potential oscillations [16–18]. Grid cells can update placecells via the extensive projections from entorhinal cortex layer II to dentate gyrusand CA3 and from layer III to region CA1 [45, 61]. The connectivity from grid cells to placecells could be formed by different computational mechanisms [45, 62, 63]. Place cells can become associated with headdirection activity via direct projections from region CA1 to the postsubiculum [58], or via indirect projections from region CA1 to the subiculum [61, 64], and projections fromthe dorsal and distal regions of the subiculum to the postsubiculum and medialentorhinal cortex [65], both of which contain head direction cells.


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)

Model of episodic encodingand retrieval of trajectories.  Top:Schematic representation of connectivity between grid cells, place cells, andhead direction (HD) cells.  Bottom: exampleof trajectory retrieval activity in each region.  Trajectory experienced during encoding isshown in gray.  (a) The location coded bythe oscillation phase of entorhinal grid cell membrane potential is plotted asa dashed line that follows the actual trajectory in gray.  Grid cell phase is put through the inversehead direction transformation to obtain coded location.  Phase shifts are driven by retrieved headdirection until next place cell is activated, then phase moves in new directiondependent on next active head direction cell. (b) Sequentially activated place cell representations are shown as opencircles.  (c) Each place cell activates acorresponding head direction representation, with direction shown as a short,straight, black line.  This drives thenext period of update of the grid cell phase.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2480478&req=5

fig6: Model of episodic encodingand retrieval of trajectories. Top:Schematic representation of connectivity between grid cells, place cells, andhead direction (HD) cells. Bottom: exampleof trajectory retrieval activity in each region. Trajectory experienced during encoding isshown in gray. (a) The location coded bythe oscillation phase of entorhinal grid cell membrane potential is plotted asa dashed line that follows the actual trajectory in gray. Grid cell phase is put through the inversehead direction transformation to obtain coded location. Phase shifts are driven by retrieved headdirection until next place cell is activated, then phase moves in new directiondependent on next active head direction cell. (b) Sequentially activated place cell representations are shown as opencircles. (c) Each place cell activates acorresponding head direction representation, with direction shown as a short,straight, black line. This drives thenext period of update of the grid cell phase.
Mentions: Theinteraction of head direction cells and grid cells described here provides apotential mechanism for episodic memory involving the storage of trajectoriesthrough space and time [57]. As shown in Figure 6, thismodel uses a functional loop that encodes and retrieves trajectories via threestages: (1)head direction cells h(t) update grid cells, (2) grid cells g(t) update place cells, and (3) place cells p(t) activate associated head directionactivity [57]. This model is consistentwith the anatomical connectivity (seeFigure 6). Thehead direction cells could update grid cells via projections from thepostsubiculum (dorsal presubiculum) to the medial entorhinal cortex [58–60], causing updating of persistent firing as described above, orinfluencing the phase of membrane potential oscillations [16–18]. Grid cells can update placecells via the extensive projections from entorhinal cortex layer II to dentate gyrusand CA3 and from layer III to region CA1 [45, 61]. The connectivity from grid cells to placecells could be formed by different computational mechanisms [45, 62, 63]. Place cells can become associated with headdirection activity via direct projections from region CA1 to the postsubiculum [58], or via indirect projections from region CA1 to the subiculum [61, 64], and projections fromthe dorsal and distal regions of the subiculum to the postsubiculum and medialentorhinal cortex [65], both of which contain head direction cells.

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
Related in: MedlinePlus