Chapter 12
The Central Nervous System
457
12
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.
Figure 12.21a
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.
Nondeclarative memory
is less conscious or even uncon-
scious learning. Categories of nondeclarative memory are
procedural (skills) memory
(piano playing),
motor memory
(riding a bike), and
emotional memory
(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
Basal
forebrain
Prefrontal
cortex
Smell
Taste
Thalamus
Touch
Hearing
Vision
Hippocampus
Thalamus
Prefrontal
cortex
ACh released
by basal
forebrain
Association
cortex
Sensory
input
Thalamus
Premotor
cortex
Dopamine released
by substantia nigra
Association
cortex
Basal
nuclei
Sensory and
motor inputs
Medial temporal lobe
(hippocampus, etc.)
Premotor
cortex
Thalamus
Substantia
nigra
Basal
nuclei
(a) Declarative memory circuits
(b) Procedural (skills) memory circuits
Figure 12.21
Proposed memory circuits.
(a)
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.
(b)
Sensory
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.
previous page 491 Human Anatomy and Physiology (9th ed ) 2012 read online next page 493 Human Anatomy and Physiology (9th ed ) 2012 read online Home Toggle text on/off