limbic system 2 Flashcards
What is the major input circuit pathway through the hippocampal formation?
Cingulum-> large input ->(Pyramidal cells)Entorhinal cortex-> subiculum (perforant pathway) -> (granule cells)dentate
Long term potentiation(LTP) - enhanced signal transmission between neurons (synaptic plasctity) was discovered in the hippocampal synapse
Which sector doe sthe dentate granule cells project to the hippocampus pyramidal cell dendrites?
primarily of CA3 sector
What are Hippocampus pyramidal axons form a surface white layer called?
What does the alveus become?
What becomes the crus of the fornix?
alveus- is Hippocampus pyramidal axons
alveus collects medially to form fimbrae
crus of the fornix is formed fro the fimbrae
Where does hippocampus pyramidal branches project to?
Where does CA1 projrcts through?
What is the closed feed-back loop importnt for?
Hippocampus pyramidal brs. (Schaefer collaterals) project to CA1
CA1 projects through subiculum back to entorhinal cortex (figure “8”)
This closed feed-back loop is probably important for memory consolidation
What is the induseum griseum?
Posteriorly the hippocampus attenuates to a thin tail-like extension which passes above the corpus callosum where it is called the induseum griseum
What does the fimbrae become when it leaves the dorsal surface of the hippocampus?
Where does hippocampal fibers cross?
When the fimbria leaves the dorsal surface of the hippocampus, it becomes fornix
Just before the crurae form the body, hipppocampal commisural fibers cross
What does lesions of the hippocampus cause?
antergrade amnesia
especially for declaritive memory (facts, names places)
Where is the amygdala located?
anterior and medial to the hippocampus
it appears as a homogenous nuclear mass compared to the hippocampus
What is the amygdala?
Amygdala is a large basal nuclear mass not directly involved in the motor system
It has an essential role in emotions and their behavirial expression
many of the connections are recipricol
What occurs in the amygdala?
Stimulus associations occur- fear conditioning
plays a role in PTSD
signal flow favors lateral to medial (afferen to efferent part)
What are the efferent fiber bundles of the amygdala?
stria terminalis (to septal area and hypothalamus)
ventral amygdalofugal pathway to hypothalamus, thalamus , & PLIC
simplified amygdala connections
What two bodies does the stria terminalis lie between?
Fornix body
Caudate body
lies on the dorsal aspect of the thalamus
What is the bed nucleus of the stria terminalis and what has it benn implicated in?
An xtension of the amygdala thhat has bee implicated in fear, stress, anxiety and drug addiction
Where does the amygdalofugal fibers pass to the hypothalamus?
what does the amygdalocortical fibers use?
Amygdalofugal fibers pass to the hypothalamus under lenticular nucleus
Amygdalocortical fibers use the internal capsule
What is the striatum?
What is it a component of?
what is it required for?
striatum= (dorsal striatum(caudate + putamen)+ (ventral striatum(nucleus accumbens))
major component of the motor system
it is required for normal movement control
What regulates motor-motor behavior?
What is the substantia nigra?
What is the effects of dopamine?
Motor motor behavior is highly regulated by dopamine neurons in the midbrain
The substantia nigra regulates “regular “ voluntary motor behavior (e.g., walking)
The dopamine has its effects in basal nuclei call the dorsal striatum
What is the mesolimbic system?
what does it regulate?
Where does the ventral tegmental area also projects?
-mesolimbic system- (VTA + ventral striatum)
VTA -Dopamine from the ventral tegmental area regulates emotional behavior
Ventral striatum (nucleus accumbens) intergrates limbic motor
VTA dopermergenic neurons also projects to the frontal cortex unlike the substantia nigra
What has the nucleus accimbens been implicated in?
in emotional aspects of behavior including motivation, reward, reinforcement, euphoria (pleasure) , and addiction.
Facial expression, body language, crying and laughter, etc. are all emotional states with motor components (somatic expression)
Multiple drugs of abuse include modulation of VTA-accumbens dopamine among their effects at either or both VTA and nucleus accumbens.
What is the blood supply of the amygdala and hippocampus?
Amygdala predominantly supplied by anterior choroidal br. of MCA
Hippocampus predominantly supplied by brs. of PCA
What does lesion effects on the amygdala include?
Lesion effects on the amygdala include placidity, short term memory problems, and sexual changes
