limbic system Flashcards
what is the limbic lobe
- Telencephalic structures that circle the interventricular foramen of Monro and border the
diencephalon
what matter is the limbic lobe comprised of
- Comprised of grey matter with a histological
structure simpler than that of neocortex
what does the limbic lobe include
Includes: parahippocampal gyrus and
hippocampus, retrosplenial area, cingulate gyrus,
subcallosal gyri.
what is the limbic system
Location an function
- Structures that interface between the cortex
and the hypothalamus and modulate the motivational and emotional functions
initiated by the hypothalamus
what does the limbic system include
- Limbic system includes all structures that
are linked to the limbic lobe and that
project, ultimately, to the hypothalamus or
its targets
what does the limbic recieve input from
What does it modulate
- Limbic system structures receive cortical
input and modulate hypothalamic functions.
the lumbic system functions in controll of ____ , ____, and ______
emotion, motivated behavior, and memory
what do lesions of limbic structures not result in
- Lesions of limbic structures do not result in
paralysis or sensory deficits.
how do seizures activity or eliectrical stimulation in limbic strucuters produce
Seizure activity or electrical stimulation in
limbic structures do not produce clonic
movements or sensory perceptions.
what does excititation of limbic structures evoke
- Excitation of limbic structures evokes
emotional states or memory fragments
papez circuit
- Start in the hippocampus
- Output pathway of the HPC is the fornix
- Fornix ends in mammillary bodies, which project to the anterior nucleus of the thalamus (AT) via the mammillothalamic tract (MThT)
- From the AT, there are fibers that project through the internal capsule to the cingulate
gyrus - Cingulate gyrus project to the entorhinal cortex, which feeds cortical information to the
hippocampus.
fornix ( top)
hippocampus ( bottom)
Fx
HPC
EC = entorhinal cortex: cortical input to the hippocampus
where does the fornix terminate
mammilary bodies
MThT: mammillothalamic tract
AT = anterior nucleus of the thalamus
Output of AT → cingulate gyrus of the cortex via the internal capsule
declerative memory
short term memory > consolidation» long term memory
memory theory
- what is it
- what is involoved in memory consolidation
Theory: when we learn something, it enters our short term memory. If we study it over and over
(pyramidal fibers pierce the pons!), information will get consolidated and put into long term
memory. This process of going from short to long term memory is called memory consolidation.
The hippocampus is involved in memory consolidation.
who is henry gustav molasion
he had a degeneratied hippocampis on one side and this was producing seizures.
his hippocampus was taken out on the opposite side in an attempt to stop the seizure.
- he then had bilateral hippocampaeltomy bc both of his hippmcampuses were non funcitonal
what did HM have
Severe memory deficit.
- Loss of memory consolidation
-
place cells of hippocampus function
d – spatial navigation
what would happen if you put HM in a new city vs back at home
HM: you couldn’t put him in a new city; he’d get lost. But if you put him back in montreal, he could
get along just fine since that was in his long term memory before his hippocampus degenerated
and his surgery
role of hippocampus
- Memory consolidation
- Spatial navigation
what is the uncus next to
- what is inside the uncus
uncus is next to the parahippocampal gyrus. Inside the uncus is the amygdala
amygdala pathways
- Stria terminalis
- Ventral amygdalofugal pathway
ST = stria terminalis. Like the fornix. Has a c-shape, and goes from the amygdala to the
hypothalamus.
VAF = ventral amydalofugal pathway. more direct route from amygdala to the hypothalamus
what emotion is the amygdala associated with
fear
what is a major target of the amygdala
hypothalmus
what are the major inputs and outputs of the amygdala
Hypothalamus
– Brainstem
– Hippocampus and entorhinal cortex
– Mediodorsal nucleus of thalamus
– Anterior cingulate cortex
– Prefrontal cortex
– Olfactory tract
role of amygdala
Amygdala is the integrative center for
emotions, emotional behavior and
motivation.
kluver-bucy syndrome symptoms
- removed amygdala bilaterally in monkeys what were the symptoms
- Tameness
- Lack of fear and other emotional reactions
- Hypersexuality
- Bulemia
- Oral tendencies
- Hypermetamorphosis
temporal lobe epilepsy
- aggression
- panic attacks
lesions of amygdala
- placidity
- flatness of affect
- failure to discriminate emotional expressions
- loss of emotional memory processing
path when you see something scary
- If someone sees
something scary like a snake, the visual pathway goes to the thalamus directly (via the dotted
blue arrow) to the amygdala → fear/panic reaction. - Later, the person analyzes it (pathway to the visual cortex, then to the amygdala) and recognizes
that it’s just a garden snake and nothing to fear
