Fear
Conditioning
Fear conditioning
is an experimental procedure in which an organism is taught to fear a
harmless, neutral stimulus, such as a tone. Conditioning is accomplished
by pairing the neutral stimulus with an aversive stimulus, such as a foot
shock. After a few associations, the animal comes to exhibit fear responses
whenever the tone is presented, representing learning. In rats, these
responses include freezing and an elevation of blood pressure and heart
rate which are almost identical to the types of physiological and behavioral
responses displayed by humans with phobias or unexplained irrational fears.
Emotional arousal in the laboratory has been examined under two major
types of conditions: fear conditioning (as described above) and a task
known as the inhibitory avoidance task,
which is described elsewhere on this web page.
The specific role of a brain structure known as the amygdala in these
procedurally unique learning tasks has been the subject of some debate.
Two roles for the amygdala have been suggested. One position views the
amygdala as the locus of emotional memory, where it is required for learning
associations in new emotional situations, (i.e. acquisition), storing
the associations into a more permanent form (i.e. retention), and expression
of emotional memories through appropriate behavioral responses. The other
position considers the amygdala as a critical modulator of the neural
processes that are necessary for newly learned information to be consolidated
or stored in other areas of the brain where long-term memories may be
localized.
Fear conditioning procedures and the inhibitory avoidance learning task
both appear to be evaluative tasks for fear learning and memory. Thus,
if a common neural pathway mediates both, it would follow that experimental
manipulations that influence one would have a similar effect on the other.
Conversely, if different underlying neural pathways are responsible for
each type of learning, then a difference in results might occur from similar
experimental methods. It is the goal of experiments conducted in this
laboratory to provide further insight into the nature of fear conditioning
and how it relates to inhibitory avoidance.
Cedric
Williams
The University of Virginia
Psychology Department