Forebrain and Limbic System Flashcards
the diencephalon is anatomically a large part of the forebrain, what are the 4 divisions of the diencephalon
epithalamus
thalamus
hypothalamus
subthalamus
what seperates the hypothalamus from the thalamus
hypothalamic sulcus
what are the 2 main regions of the epithalamus
- pineal gland
- habenula
what is the function of the pineal gland
secrete melatonin and regulate sleep wake cycle
what is the major input, and major output for the habenula (part of epithalamus)
input - stria meddularis and limbic
output - habenulointerpeduncular tract to midbrain
what is known as the “gateway to the cortex”, and why does it get this name
thalamus - relays all sensory pathways to the cortex (except olfaction)
there are many types of thalamic nuclei, what anatomically divides these subdivisions of nuclei w/in the thalamus
internal medullary lamina (IML)
what thalamic nuclei does not follow the general scheme for thalamic nuclei, and is known as a gatekeeper nuclei
reticular nucleus
all thalamic nuclei (except reticular) follow the same general theme as what they are composed of, what is it ?
- projection neurons to cortex
- interneurons regulating firing
what are the 2 basic types of inputs to the thalamus
- specific inputs
- regualtory inputs
what are the 3 broad types of thalamic nuclei
1 - relay nuclei
2 - association nuclei
3 -intralaminar and midline nuclei
what type of thalamic nuclei recieve input from well defined subcortical sources and then project to cortex
relay nuclei
what type of thalamic nuclei recieve distinct input from the basal ganglia and limbic strucutres
intralaminar and midline nuclei
what type of thalamic nuclei recieve input from the association cortex
association nuclei
what specific nueclei of the thalamus is an important source of regulatory input to the thalamus
reticular nucleus
what is the output of the reticular nucleus
inhibitory axons to thalamus
** no projections to cortex **
what are the specific motor relay nuclei of the thalamus
- ventral anterior (VA)
- ventral lateral (VL)
what is the specific sensory relay nuclei for the the body in the thalamus
ventral posterior lateral (VPL)
what is the specific sensory relay nuclei for the face
ventral posterior medial (VPM)
what is the specific thalamic nuclei that is a relay nucleus for the limbic system
anterior nucleus
what is the thalamic relay nuclei for vision
lateral geniculate nucleus
what is the thalamic relay nucleus for hearing
medial geniculate nucleus
what specific thalamic nuclei is a component of the reticular activating system
intralaminar nucleus
what are the two main association nuclei of the thalamus
1 - dorsomedial (DM) - from the prefontal association cortex
2 - Pulvinar LP complex - from the parietal-occipital-temporal lobe of the association cortex
what fibers pass through the internal capsule
- thalamocortical fibers
- corticothalamic fibers
what is the lenticular nucleus made up of
putamen and globus pallidus
what are the 5 parts of the internal capsule
1 - anterior limb 2 - posterior limb 3 - genu 4 - retrolenticular 5 - sublenticular
a stroke to what part of the internal capsule would be the most severe clinically ?
stroke in the posterior limb = worst
**cuz would result in contralateral motor loss **
what is the main function of the limbic system
generate fellings/emotions from sensory inputs
what are the primary structures (parts of brain) that make up the limbic system
- amygdala
- hippocampus
- parahippocampal gyrus
- cingulate
- hypothalamus
what part of the brain is responsible for maintaining homeostasis
hypothalamus
what are the 3 types of connections with the hypothalamus
- limbic system
- pituitary gland
- visceral/somatic nuclei
what is the longitudinal organizational regions of the hypothalamus
- anterior region
- tubular region
- posterior region
what is the medial-lateral organization of the hypothalamus
- medial
- perivent
- lateral
the lateral region of the hypothalamus is a rostral continuation of ___________ whereas the perivent region is the rostral continuation of __________
reticular formation
periaqueductal gray
what are the 2 MAIN inputs to the hypothalamus
1 - forebrain, especially limbic system
2 - brainstem and spinal cord
septal nuclei, ventral striatum, insula, hippocampus, and amygdala are all hypothalamic inputs from what main area ?
forebrain (limbic structures)
T/F the hypothalamic outputs use seperate pathways than the inputs.
F - both inputs and outputs use the same pathway
what are the 2 lobes of the pituitary gland
adenohypophysis (anterior lobe)
neurohypophysis (posterior lobe)
what are the 2 hormones the hypothalamus secretes
antidiuertic hormone (ADH) oxytocin
what is the emotion center of the brain
amygdala
largely involved in emotion-related aspects of learning
where where is the amygdala located anatomically
anterior and medial temporal lobe
the amygdala has 3 nuclei groups, what are they and what is the general function of each
medial nuclei -olfaction
central nuclei - emotional responses
basolateral - emotional responses
the amygdala recieves inputs from almost everywhere in the brain, what are the 4 basic input routes ?
1 - stria terminalis
2 - ventral amygdalofugal (VAG)
3 - lateral olfactory tract
4 - direct from temporal lobe cortex and hippocampus
T/F The output routes for the amygdala are the same as the input routes ?
True (stria terminalis, VAG, lateral olfactory tract)
the amygdala links perception of a situation with an emotional response, especially when ?
during danger situations
hypothalamic inputs go through the _______ bundle and __________ fasiculus
medial forbrain bundle (MFB) and dorsal longitudinal fasiculus (DLF)
the limbic loop in the basal ganglia associates stimuli with _______ resulting in what ?
rewards, resulting in increased Ventral striatum dopamine release
what is Kluver-Bucy Syndrome, and a lesion to what part of the brain would cause this
where one beomes fearless with no emotional reactions, men try to fuck everything
-occurs when lesion to amygdala
what is the main function of the hippocampus
formation of new memories and past experiences
***also known as Declarative (explicit) memory
where is the hippocampus anatomically
little swirl in the medial temporal lobe
what is the most important hippocampal output pathway
fornix
what are the 3 distinct zones of the hippocampus
- dentate gyrus
- hippocampus proper
- subiculum
what are the “interlocking C’s” in hippocampal structure
dentate gyrus and hippocampus proper
starting from afferents from the sensory cortex, expalin the hippocampal loop or input/output flow
affferents —> entorhinal cortex —> dentate gyrus —–> CA3 —-> CA1 —-> subiculum —-> fimbira and back to entorhinal cortex —-> back to sensory cortex
most sensory info comes into the hippocampus in the _________ and most outflow is through the _______ ?
entorhinal cortex - IN
subiculum to fornix -OUT
what is the circuit of Papez
he was the first to describe the neural circuit for control of emotional expression, over time this theory has been modified though and is known to function in memory (not emotion)
