Download The Basal Forebrain - People Server at UNCW

The Telencephalon
– Basal ganglia
– Limbic System
– Cerebral cortex
» “Basal Forebrain”
»
Basal ganglia
»
limbic system
Basal Ganglia
• Neostriatum
– Caudate (kaw-date) nucleus and putamen (pew-TAY-men)
• Globus Pallidus ( GLOB-us PAL-i-dos)
• Substantia nigra (included by functional
anatomical relationship)
• Subthalamus
• others
not
Basal ganglia- Complex ccts
The basal ganglia are involved in motor regulation, but are only one
component of the control of behavior. The way in which the basal ganglia
controls movement is complicated and not completely understood, but at his
time may be fairly described as the gate-keeper of movement. Disorders of
the basal ganglia can either lead to too much behavior or too little behavior.
Basal Ganglia-Neostriatum
( composed of the caudate nucleus and the Putamen)
The Nigro-striatal pathway- the
behavioral “grease” system
The Globus Pallidus ( the striato-pallidal
circuit= the behavioral “brakes” system)
Basal Ganglia Syndromes
too much or too little behavior
• Damage to the Nigro-striatal pathway
– Parkinsons
(not enough behavior)
– http://video.google.com/videosearch?hl=en&rls=GGIC,GGIC:200701,GGIC:en&um=1&q=parkinsons&ndsp=20&ie=UTF-8&sa=N&tab=iv#
– http://video.google.com/videosearch?hl=en&rls=GGIC,GGIC:200701,GGIC:en&um=1&q=parkinsons&ndsp=20&ie=UTF-8&sa=N&tab=iv#
Basal Ganglia syndromes
• Strato-Pallidal Pathway- too much behavior
– Huntingtons
– Tourettes’
– Balisms
– Others
Dr. George Huntington, a Long Island, N.Y.
physician first described this disease in 1872. The
most famous sufferer of this disorder was probably
the celebrated folk singer Woody Guthrie, whose
wife, Marjorie noticed her husband walking
lopsidedly one day in the 1950s. She then began
to notice that his speech was becoming slurred but
it was only when he began to fly into major rages
that she realized something was severely wrong
with her husband. Eventually, he lost all ability to
talk, to read or walk. The only way he could
communicate with his wife and children was by
waving his arm at cards printed with the words
'Yes' and No'.
.
• The disease was Huntington's Chorea,
which is an inherited, degenerative
disorder of the Central Nervous System,
caused by a dominant gene. This means
that everyone who inherits the gene from
one of his/her parents WILL develop the
disease, and the likelihood of doing so is
therefore 50%. The specter of this cruel
disease continues to hang over the entire
Guthrie family
• Huntington's Chorea is a particularly devastating
disease because symptoms normally do not
occur until after the age of 35, but can onset
later (the earlier the onset, the more severe the
disease tends to be). It is principally a movement
disorder, with the first observable symptoms
manifesting themselves as 'clumsiness', but as
the disease progresses the movements become
uncontrollable. These movements appear to be
very bizarre and include odd bodily postures.
Other symptoms are also apparent including
forgetfulness and irritability or withdrawing (in
the early stages) progressing to dementia with
severe memory loss and lack of reasoning.
• Huntington's Chorea is principally
characterized by hyperkinesias abnormal, purposeless, involuntary motor
movements that can occur spontaneously
or only when the patient is trying to do
something. These movements may be
repetitive or non-repetitive.
Tourettes Syndrome
• TS usually becomes apparent in children
between ages 2 to 15, with approximately
50% of patients affected by age 7. The
age of symptom onset is typically before
the age of 18. TS is more frequent in
males than females by a ratio of about 3 or
4 to 1. The disorder is thought to affect
0.1% to 1.0% of individuals in the general
population.
Tourettes
• Motor tics
Initially, patients develop sudden, rapid, recurrent, involuntary
movements (motor tics), particularly of the head and facial area. At
symptom onset, motor tics usually consist of abrupt, brief, isolated
movements known as simple motor tics, such as repeated eye blinking
or facial twitching. Simple motor tics may also include repeated neck
stretching, head jerking, or shoulder shrugging. Less commonly, motor
tics are more "coordinated," with distinct movements involving several
muscle groups, such as repetitive squatting, skipping, or hopping.
These tics, referred to as complex motor tics, may also include
repetitive touching of others, deep knee bending, jumping, smelling of
objects, hand gesturing, head shaking, leg kicking, or turning in a
circle. In addition to affecting the head and facial area, motor tics also
affect other parts of the body, such as the shoulders, torso, arms, and
legs. The anatomical locations of motor tics may change over time.
Rarely, motor tics evolve to include behaviors that may result in selfinjury, such as excessive scratching and lip biting.
Vocal tics
•
Vocal tics are sudden, involuntary, recurrent, often relatively loud
vocalizations. Vocal tics usually begin as single, simple sounds
that may eventually progress to involve more complex phrases and
vocalizations. For example, patients may initially develop simple
vocal tics, including grunting, throat clearing, sighing, barking,
hissing, sniffing, tongue clicking, or snorting. Complex vocal tics
may involve repeating certain phrases or words out of context, one's
own words or sounds (palilalia), or the last words or phrases spoken
by others (echolalia). Rarely, there may be involuntary, explosive
cursing or compulsive utterance of obscene words or phrases
(coprolalia).
LIMBIC SYSTEM
•
•
•
•
•
Basal forebrain
Interconnected
Affective responses
Impulsive…low consciousness
Reciprocally connected with frontal cortex
– Many structures
•
•
•
•
Hippocampus
Amygdala
Septum
Nucleus accumbens
View of some limbic system
structures
Hippocampus (seahorse?)
Based on early neuroanatomical observations and studies with psychoactive
drugs, the septohippocampal circuit has been proposed as a model for
anxiety disorders.
Note*-Memory processes can be
profoundly affected by life experiences. In
particular, stress has proved to be a major
modulator of memory function.1–4
Hippocampus and Memory:
“H.M.”
Henry Gustav Molaison, lost completely
the ability to form new memories
following a radical surgical procedure
to treat his severe and intractable
epilepsy.
1953; William Scoville, a neurosurgeon
removed both of H.M.'s hippocampi in
their entirety, together with some of the
surrounding structures.
profound anterograde and retrograde
amnesia
H.M.'s amnesia was so severe that he
never recognized Dr. Brenda Milner,
despite working with her for more than
50 years.
Hippocampus and spatial
processing
an apparatus often used to study “Place cells” of the
hippocampus
How action potentials from place cells
may be recorded
Visual representation of action potentials recorded from
one hippocampal Place cell
• The cell fires predominantly in association
with one environmental location
Amygdala (almond shaped?)
Connected with and anterior to the hippocampus
The Amygdala receives input from many other
brain areas that would logically allow evaluation of
emotional significance of experiences