House of Mind

"Biology gives you a brain. Life turns it into a mind" - Jeffrey Eugenides

  • 14th March
    2011
  • 14
Cognitive Mapping and Place Cells
(Click on the picture above to read the review)
A friend of mine, Katie, once asked me if I knew anything about place cells. Considering that attentional and memory mechanisms are not my area, I replied that I had no idea what she was talking about. She sent me this review article, which I found very enlightening. After all, it makes sense for these kinds of cell to exist…
For quite some time now, neuroscientists have been at work trying to determine the scope of the role that the hippocampus plays in memory processing (encoding, storing, retention of information). Many groups have tried to clarify on the issue by employing neuropsychological and electrophysiological methods in animal models. As a result, many proposals on the hippocampal role in memory processing have emerged. 
Among the proposals that have attracted considerable attention, is the view that the hippocampus mediates a neural representation that corresponds to a particular visual space, a cognitive map. This cognitive map is believed to constitute an abstract coordinate grid of two-dimensional space created by a network of intrinsic hippocampal connections. Thus, at physiological level, a place cell reflects the occurrence of the rat at a particular coordinate in the map.
Cognitive mapping theory is founded on a systematic analysis of the behavioral deficits observable/measurable following hippocampal damage.  One of the examples for cognitive mapping theory is the discovery of specific hippocampal neurons (i.e. CA1, CA2, for example) that increase their firing rate when an animal (rat) is in a particular location (“place field” in an environment. Somehow, the firing rate/activity of these neurons is able to reflect spatial changes in the moving animal. Therefore the activity of many place cells reflects the presence and topography of multiple environmental cues. 
Moreover, other groups (O’ Keefe & Conway, 1978) have studied place cell responses after manipulating (or removing) these environmental cues and have found that many place cells maintained their spatial firing patterns. Others (Muller & Kubie, 1987) have found that some place fields can “scale up” in size (enlarge) while still maintaining the same shape and location. However, if the shape of the environment changed, spatial firing patterns were either lost or changed unpredictably. In accordance, O’ Keefe and Burgess (1996) went on to show that the shape and locus of place fields (in a simple rectangular chamber), were determined by the dimensions of, and of spatial relations between, the walls of the environment. 
Additional features of place cells that are consistent with a role in spatial memory include: 
Place cells may have the same firing patterns for months. 
Firing patterns may persist even if environmental cues are removed or even in total darkness. 
Spatial coding of place fields are determined by the orientation of the maze remembered by the rat. 
Existence of location-specific activity in these cells.
Newer currents of thought suggest that these cells may not constitute a cognitive map but rather reflect memory space (more in depth discussion in the review listed below). 
Disclaimer: These are the basics about place cells. Like many topics in neuroscience, there’s a lot of debate surrounding these cells and their function. Some newer studies are aimed at determining whether place cells are organized as an actual spatial map within the brain and whether or not they exclusively or predominantly encode spatial cues. 
Helpful NYU link: Place Cells in the Hippocampus
Source:
Eichenbaum. 1999. The Hippocampus, Memory and Place Cells: Is it spatial memory or memory space? Neuron. 23: 209-226.

Cognitive Mapping and Place Cells

(Click on the picture above to read the review)

A friend of mine, Katie, once asked me if I knew anything about place cells. Considering that attentional and memory mechanisms are not my area, I replied that I had no idea what she was talking about. She sent me this review article, which I found very enlightening. After all, it makes sense for these kinds of cell to exist…

For quite some time now, neuroscientists have been at work trying to determine the scope of the role that the hippocampus plays in memory processing (encoding, storing, retention of information). Many groups have tried to clarify on the issue by employing neuropsychological and electrophysiological methods in animal models. As a result, many proposals on the hippocampal role in memory processing have emerged. 

Among the proposals that have attracted considerable attention, is the view that the hippocampus mediates a neural representation that corresponds to a particular visual space, a cognitive map. This cognitive map is believed to constitute an abstract coordinate grid of two-dimensional space created by a network of intrinsic hippocampal connections. Thus, at physiological level, a place cell reflects the occurrence of the rat at a particular coordinate in the map.

Cognitive mapping theory is founded on a systematic analysis of the behavioral deficits observable/measurable following hippocampal damage.  One of the examples for cognitive mapping theory is the discovery of specific hippocampal neurons (i.e. CA1, CA2, for example) that increase their firing rate when an animal (rat) is in a particular location (“place field” in an environment. Somehow, the firing rate/activity of these neurons is able to reflect spatial changes in the moving animal. Therefore the activity of many place cells reflects the presence and topography of multiple environmental cues. 

Moreover, other groups (O’ Keefe & Conway, 1978) have studied place cell responses after manipulating (or removing) these environmental cues and have found that many place cells maintained their spatial firing patterns. Others (Muller & Kubie, 1987) have found that some place fields can “scale up” in size (enlarge) while still maintaining the same shape and location. However, if the shape of the environment changed, spatial firing patterns were either lost or changed unpredictably. In accordance, O’ Keefe and Burgess (1996) went on to show that the shape and locus of place fields (in a simple rectangular chamber), were determined by the dimensions of, and of spatial relations between, the walls of the environment. 

Additional features of place cells that are consistent with a role in spatial memory include: 

  • Place cells may have the same firing patterns for months. 
  • Firing patterns may persist even if environmental cues are removed or even in total darkness. 
  • Spatial coding of place fields are determined by the orientation of the maze remembered by the rat. 
  • Existence of location-specific activity in these cells.

Newer currents of thought suggest that these cells may not constitute a cognitive map but rather reflect memory space (more in depth discussion in the review listed below). 

Disclaimer: These are the basics about place cells. Like many topics in neuroscience, there’s a lot of debate surrounding these cells and their function. Some newer studies are aimed at determining whether place cells are organized as an actual spatial map within the brain and whether or not they exclusively or predominantly encode spatial cues. 

Helpful NYU link: Place Cells in the Hippocampus

Source:

Eichenbaum. 1999. The Hippocampus, Memory and Place Cells: Is it spatial memory or memory space? Neuron. 23: 209-226.

  1. fuckmycorpse reblogged this from hope-is-your-enemy
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    Yo my sis is working on this! It’s pretty neato!
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    There’s this room in the lab that looks like an LSD trip for mice, so I asked someone today finally what the hell they...
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