Working memory, a type of transient memory that enables
us to retain what someone has said just long enough to reply,
depends in part on the prefrontal cortex. Researchers discovered
that certain neurons in this area are influenced by neurons
releasing dopamine and other neurons releasing glutamate.
While much is unknown about learning and memory, scientists
can recognize certain pieces of the process. For example, the
brain appears to process different kinds of information in
separate ways and then store it differently. Procedural knowledge, the
knowledge of how to do something, is expressed in skilled behavior
and learned habits. Declarative knowledge provides an explicit,
consciously accessible record of individual previous experiences
and a sense of familiarity about those experiences. Declarative
knowledge requires processing in the medial temporal region and
parts of the thalamus, while procedural knowledge requires processing
by the basal ganglia. Other kinds of memory depend on
the amygdala (emotional aspects of memory) and the cerebellum
(motor learning where precise timing is involved).
An important factor that influences what is stored and how
strongly it is stored is whether the action is followed by rewarding
or punishing consequences. This is an important principle
in determining what behaviors an organism will learn and
remember. The amygdala appears to play an important role in
these memory events.
How exactly does memory occur? After years of study, there
is much support for the idea that memory involves a persistent
change in the relationship between neurons. In animal studies,
scientists found that this occurs through biochemical events in
the short term that aΣect the strength of the relevant synapses.
The stability of long-term memory is conferred by structural
modifications within neurons that change the strength and
number of synapses. For example, researchers can correlate
specific chemical and structural changes in the relevant cells
with several simple forms of behavioral change exhibited by the
sea slug Aplysia.
