Biology Reference
In-Depth Information
3.3. Learning-dependent modifications of place fields
Different learning experiences are able to change the firing fields of place cells, although
the main environmental cues stay stable. Place field remapping can be triggered by a discrete
learning event in the same, unchanged environment (Moita
et al.
, 2004) — in a form of
Pavlovian conditioning called contextual fear conditioning. An electrical footshock is applied
as an unconditional stimulus while the environment effectively acts as a conditional stimulus
that, after training, can itself elicit a behavioral freezing response. The cell's place field
remapped completely after contextual fear conditioning.
Figure 3. Learning-dependent pattern separation of place fields. A. Single place cell developed the
ability to distinguish a square from a circular recording environment over the course of several sessions.
B. Example of a place cell that is persisting to fire with the same frequency only in a circular, but not in
a square recording box (Adapted from Lever et al., 2002 and Jeffery and Hayman, 2006). Higher
intensity of grey color represents higher frequency of the unit discharge (Hz). C. Similarly, in two
identical novel environments that differ only by their location in space the place cells fire in a similar
pattern. D. Development of remapping by a single place cell is observed over the course of a single
session. Learning-dependent experience resulted in pattern separation between the north- and south-
located square. These observations show that individual cells can acquire the ability to discriminate
environments (adapted from (Jeffery & Hayman, 2004)).
