426 Neuroanatomy: Draw It to Know It
Know-It Points
Language Disorders
■ I n 9 0 % of individuals, the language centers lie within
the left hemisphere.
■ Broca’s aphasia is a non-fl uent aphasia with preserved
comprehension and impaired repetition.
■ Broca’s aphasia localizes to Broca’s area and also
involves the precentral g yrus, basal ganglia, insula,
and related white matter pathways.
■ Wernicke’s aphasia is a fl uent aphasia with poor
comprehension and impaired repetition.
■ Wernicke’s aphasia localizes to Wernicke’s area and
the neighboring supramarginal g yrus and angular
g yrus and the surrounding temporal and parietal
lobes and insula.
■ Global aphasia, which is most easily thought of as a
combined Broca’s and Wernicke’s aphasia, is due to
extensive injury to the left middle cerebral artery
territory.
■ In transcortical aphasia, the perisylvian region is spared,
which is presumably why repetition is unaff ected.
■ Conduction aphasia is a fl uent aphasia with normal
comprehension but impaired repetition; it classically
localizes to the arcuate fasciculus.Memory: Classes
■ Sensory memory is the transitory retention of a
primary sensory stimulus.
■ Short-term memory lasts for roughly 3 to 30 seconds.
■ Long-term memory refers to memories that are
anywhere from older than 30 seconds to the most
remote memories.
■ Declarative (aka explicit) memories are those that
are consciously recalled (eg, reciting a country’s
capitals).
■ Nondeclarative (aka implicit) memories are those
that are unconsciously retrieved (eg, riding a bicycle).
■ Episodic memory refers to the recollection of
episodes, typically autobiographical episodes, which
have a strong contextual stamp.
■ Semantic memory refers to our knowledge stores:
our collection of facts or information, which have no
contextual stamp.
■ Procedural memory refers to skills learning, such as
riding a bicycle.
■ Priming refers to the improved ability to identify
recently perceived stimuli in comparison to new
s t i m u l i.Memory: Capacity & Consolidation
■ Short-term memory is able to hold seven bits of
information (plus or minus two) at any given time.
■ Chunking is the process wherein we organize
information into fewer chunks or bits.
■ Encoding is the process in which information is
transformed into a format that can be stored and
retrieved.
■ Storage is the stockpiling of memory into its stored
state.
■ Retrieval is the accessing of stored memories.
■ According to multiple memory trace theory, every
time an episodic memory is retrieved, the
hippocampal–neocortical ensemble of that memory
is strengthened.
■ Anterograde amnesia is the inability to form new
memories aft er the development of amnesia.
■ Retrograde amnesia is the inability to retrieve
memories that occurred prior to the development of
the amnesia.