The Central Nervous System
are best remembered in the doing. You do not have to think
through how to tie your shoes. Once learned, nondeclarative
memories are hard to unlearn.
Brain Structures Involved in Memory
Speciﬁc pieces of each memory are thought to be stored near re-
gions of the brain that need them so new inputs can be quickly
associated with the old. Accordingly, visual memories are stored
in the occipital cortex, memories of music in the temporal cor-
tex, and so on.
But how do we create new memories? It seems that diﬀer-
ent types of memory are created in diﬀerent parts of the brain.
shows a proposed scheme of information ﬂow
for declarative memory.
Declarative (fact) memory
entails learning explicit informa-
tion, such as names, faces, words, and dates. It is related to our
conscious thoughts and our ability to manipulate symbols and
language. When fact memories are committed to LTM, they are
usually ﬁled with the context in which they were learned. For in-
stance, when you think of your new acquaintance Joe, you prob-
ably picture him at the basketball game where you met him.
is less conscious or even uncon-
scious learning. Categories of nondeclarative memory are
procedural (skills) memory
(riding a bike), and
(your pounding heart
when you hear a rattlesnake nearby). We acquire nondeclara-
tive memories through experience and usually repetition. ±ey
do not preserve the circumstances of learning, and in fact, they
by substantia nigra
Medial temporal lobe
(a) Declarative memory circuits
(b) Procedural (skills) memory circuits
Proposed memory circuits.
Information from association cortices ﬂows
to the medial temporal lobe (including the
hippocampus), which communicates with the
thalamus and prefrontal cortex. The association
cortices receive feedback from these structures.
Acetylcholine from the basal forebrain is nec-
essary for this circuit to function.
and motor inputs ﬂow through the association
cortices and are relayed to the premotor cortex.
Dopamine from the substantia nigra is neces-
sary for this circuit to function.