Limbic sys Flashcards
hypothalamus
small portion of diencephalon
important node in pathways for : autonomic , endocrine , emotion and somatic functions
goal is homeostasis
also responsible for rage, sexual behaviour, sleep, hunger
There 3 categories of interconnections in hypothalamus :
1- Those that interconnect various limbic regions
2- Those that sent output to regulate pitatuiry gland
3- interconnect brainstem and spinal cord nuclei for visceral function
What are the hypothalamus divisions
Tuberal region : tuberal cinereum and median eminence from which pituitary gland hangs (behind optic chiasm and lamina terminalis )
Posterior region : from which mammillary bodies protrude
Anterior region: preoptic, the part involved in sleep
what are the hypothalamus zones
Periventrucular zone : aling wall of 3rd ventricle, continues with PAG
Lateral zone : contuneus with reticular formation of midbrain
Medial zone: between these twom contains hypothalamic nuclei
Between medial and lateral zones passes the fornix
-Pervientrucnalar and lateral zone contain maintinf axons, and other contain hypothamauc nuclei
what are the hypothalamic nuclei
Hypothalamus nuclei
Suprachiasmiatic nucleus : internal clock for caradian rhythms responds to melatinin from ouneal gland, connected to retina ro reset clock to daylight input
Arcuate nucleus : feeding begavioiur aling with ventromedial and ventrolateral
preoptic nucleus : sleep promoting
Mammillary bodies : memory formation
what are the inputs to hypothalamus
Inputs to hypothalamus from forebrain/limbic areas and the brainstem/spinal cord
inputs from brainstem/spinal cord bring visceral and somatic info
Inputs from forebrain and limbic area help mediate autonomic and somatic aspects of affective states
— from septal nuclei (“pleasure zone”), ventral striatum, OFC, retina
— hipocampus , amygdala
What are the outputs of hypothalamus ?
Outputs from hypothalamus largely are reciprocal of inputs
Except the :
mammilothalamic tract
goes to anterior nucleus, major role in memory system
What are the voluntary and involuntary functions of hypothalamus ?
Hypothalamus controls many bodily levels of homeostasis: temp (fever sweat chills), pH, hydration, glucose concentration
Also control voluntary functions: micturation (urination), defecation, sexual activity, eating - bodily functions that are only done in the context of socially appropriate situations (thank you cerebral cortex)
what are the components of limbic system ?
Limbic system: cingulate gyrus, parahippocampal gyrus, hippocampus, amygdala, septal nuclei, fornix
also hypothalamus , parts of midbrain reticular formation, olfactory areas, other neocortex
functions of the _______ is to bridge interconnections between association cortex (mostly frontal) with hypothalamus
functions of the limbic system is to bridge interconnections between association cortex (mostly frontal) with hypothalamus
Limbic system has two subsystem: _____ and _____
One centred around amygdala (“almond” ) and Other one centred around hippocampus (seahorse)
One centred around amygdala (“almond” ):
uses ventromedial PFC, anterior temporal, insula, as its major connections to neocortex,
closely connected to DM nucleus of thalamus
Major output is via septal nuclei -> hypothalamus -> midbrain reticular formation ;
Major fiber tract is medial forebrain bundle
Other one centred around hippocampus (seahorse)
uses posterior cingulate and parahimppocampal gyro as major connections to neocortex
closely connect to anterior thalamic nucleus
mammaillary body and mammillothalamuc tract major finer tract
Amygdala : Located underneath the ___ at the front of the ___, just anterior to ___ of the lateral ventricle
It is continues with the ___ cortex and __ and merges into __ gyrus
Located underneath the uncus at the front of the hippocampus, just anterior to inferior horn of the lateral ventricle
It is continues with the periamygdliod cortex and uncuss and merges into parahippocampal gyrus
The amygdala nuclei are subdivided into 3 types with different functions:
medial nuclei : vert small portions of amygdala in humans: near the periamygdaloid cortex, interconnected with olfactory system
Central nuclei : small but important for emotional responses : interconnected with hypothalamus and brainstem nuclei (eg PAG)
basolateral nuclei: most of the tissue of the amygdala; complex like cortex - contain pyramidal cells, continuous with the PHG, extensive interconnected with neocortex
Links between central and basolateral nuclei is key for experience of emotions and how they are expressed.
Amygdala inputs
Amygdala inputs
amygdala receives lots of sensory inputs, from all the senses (olfactory to the medial nucleoli the other senses to basolateral nuclei)
Also receives more complex sensory info about general physical and emotional comfort or discomfort : from orbitofrontal and anterior cingulate cortex and insula to the BL nucleus
Visceral sensory info reaches central nucleus from hypothalamus and brainstem PAG
4 pathways for inputs to Amygdala
from hypothalamus and septal nuclei (via stria terminals)
via central amygalofugal pathway from hypothalamus, thalamus, OFC and anterior cingulate
via lateral olfactory tract
directly from hippocampus and other temporal cortex.
Amygala Outputs
Amygdala sends information out along similar reciprocal fibers (stria terminalis and amygdalofugal) to similar areas as inputs
3 pathways for output from Amygdala
3 paths:
to hypothalamus and septal nuclei (via stria terminalis)
via ventral amygdolofugal pathway (to hypothamaus, thalamus, OFC, anterior cingulate) , ventral striatum, olfactory areas and brainstem
directly to hippocampus and other temporal cortex and other neocortex
Limbic fibers tracts ?
stria terminalis (efferent and afferent fibers)
ventral amygdalofugal pathway (afferent and efferrent fibers)
mammillothalamic tract (from MB to anterior thalamus)
fornix (3 parts … )
Cingulum is ___ , Cingulate gyrus is ___
Cingulum is white matter , Cingulate gyrus is gray matter
cingulum has parts:
anterior cingulate : BA 24, 32, 33 has beem associated with error detection, monitoring conflict posterior cingulate : BA 23 retrospinal cortex : 26, 29, 30 subgenual cortex : BA 25
3 fibers tract in cingulum ?
3 fibers tract in cingulum
— anterior tract
— superior tract
— descending trat
3 parts to fornix “vault/arch”
3 parts to fornix “vault/arch”
— column
— body
— crus “leg”
carries information from hippocampus to mammillary bodies (of hypothalamus)
Limbic Loop ?
inhibitory connections from ventral striatum (think DA) to ventral pallidum and VP on to DM nucleus of thalamus
excitatory connections from DM thalamus to amygdala, hippocampus and limbic cortices (OFC, cingulate, entorhinal, etc)
excitatory connections from these areas above back to ventral striatum (Dopamine)
Allows for coronation of movement based on emotion aspects of situations (among other things)
Almost anything pleasurable involves release of Dopamine (via VTA to ventral striatum)
Almost anything pleasurable involves release of DA (voa VTA to ventral striatum)
Amygdala stimulation produces emotional feelings, often _____ (esp in animals), but mostly ____ (esp in human)
Amygdala stimulation produces emotional feelings, often rage (esp in animals), but mostly fear (esp in human)
Damage to Amygdala ______ but also an _______
Damage to Amygdala dampens emotional response but also an inability to learn the memory that went with the emotional situation
..
we start life with known pleasure and pain associations, but we learn many more (stove is hot, wasp sting hurts)
Amygdala active in social emotions as well (it hurts me to see you hurt)
Amygdala activates when looking at pictures of angry, sad, sacred faces (but not happy) even though VC stroke made almost blind.
Even subjective pain activates amygdala
Emotional aspects of an event make it more memorable Amygdala projections (from \_\_\_) to the \_\_\_ are responsible for encoding the emotional tone with the memory to be stored
Emotional aspects of an event make it more memorable Amygdala projections (from basolateral nuclei) to the hippocampus are responsible for encoding the emotional tone with the memory to be stored
Bilateral temporal tobe damage: ___________
Bilateral temporal tobe damage: Kuver-Bucy syndrome
Fornix : alveus-> fimbria -> crus -> body -> columns
Fornix : alveus-> fimbria -> crus -> body -> columns
Hippocampal formation: _________
Hippocampal formation (mobile for pic) hippocampus proper (cornu ammo’s, CA fields 1 - 4) dentate gyrus subiculum input from entorhinal fimbria fornix alveus
