Place cell has place field in different part of

place cell has place field in different part of environment
 Entorhinal cortex = area of medial temporal cortex; major source of neural signals to hippocampus
o Grid cells – entorhinal neurons that have extensive array of evenly spaced place fields,
producing pattern reminiscent of graph paper
 Distance b/w evenly spaced place fields = flexible (in experimental animals kept in
smaller/oddly shaped environments, fields are closer together/sheared)
 Even spacing of grid cells could enable spatial computations in hippocampal
place cells
o Border cells – fire when subject is near borders of its immediate environment
 Nature of relationship b/w entorhinal grid cells & hippocampal place cells still debated
o 2 lines of evidence suggested responses of hippocampal place cells depend on input from
entorhinal grid cells
 1) There is major pathway from entorhinal cortex to hippocampus
 2) Entorhinal grid cells respond reflexively to location, whereas hippocampal place
cells respond to place in combination w/ other features of environment
o Discovery – properties of hippocampal place cells emerge in rat pups before stable firing of
entorhinal grid
 Challenges idea that input from entorhinal grid cells essential for hippocampal place
cell function
 Evidence that place cells can still function after entorhinal grid cells have been
eliminated
Comparative Studies of the Hippocampus & Spatial Memory
 Majority of evidence that hippocampus plays role in spatial memory comes from research on rats, but
hippocampus performs similar function in other species
o i.e. food-catching birds have remarkable spatial memories – must remember locations of
hundreds of scattered food caches to survive
 Effects of hippocampal damage on performance of spatial memory tasks in humans/other primates –
less consistent
o Could be b/c spatial memory in humans/monkeys often tested while stationary & making
judgements on computer screens, but in mice/rats/birds while navigating through test
environments
 Hippocampus implicated in several forms of memory other than spatial

o Certain cells in hippocampus shown to code for temporal aspects of an experience (time cells)
Jennifer Aniston Neurons: Concept Cells
 Major structures of medial temporal lobes – hippocampus, amygdala, medial temporal cortex
o Medial temporal cortex composed of entorhinal, perirhinal, parahippocampal cortices
 Recording electrodes implanted in patients’ brains to record activity of certain neurons as they
perform various tasks (many in structures of medial temporal lobes)
o In one of the first neurons studied this way, neuron fired in response to images of actress
Jennifer Aniston, but not to 80 other images
o Other medial temporal lobe neurons discovered that responded to other individuals or objects
known to patient
 Termed Jennifer Aniston neurons
 Concept cells – neurons that respond to ideas or concepts rather than particulars (also known as
Jennifer Aniston neurons)
o Highly selective; each neuron responded only to small # of test objects/individuals (often only
one could be found)
