Limbic System Flashcards
Limbic function
1) Emotion
2) memory
Olfactory Bulb Diagram
1) Strong communication to memory and emotion
- some of the strongest memories w/smell
2) Olfactory sensory neuron extends through the cribiform plate and olfactory epithelium
- receives signal
- synapse on cells in Glomeruli/olfactory bulb
- tufted cell and Mitral Cell
3) Tufted Cell and Mitral Cells
- both travel to the lateral olfactory tract
4) Mitral Cells project to 5 different regions of olfactory cx:
- anterior olfactory nucleus-> contralateral olfactory bulb via medial olfactory stria and anterior commissure
- olfactory tubercle
- piriform cortex
- parts of amygdala and entorhina cx
5) Tufted cells project primarily to:
- anterior olfactory nucleus
- olfactory tubercle
Olfactory bulb splits into:
1) Medial Olfactory Stria or Anterior Commisure
- contralateral olfactory bulb
2) Lateral Olfactory Tract
Vomeronasal Organ
1) receptors in nasal cavity
2) sends info to accessory olfactory bulb
- Mitral Cell-> AMYGDALA only
3) Pheromone Pathway
- only animals, not humans
- Pheromones drive the sexual behavior when females are ovulating
- Unconscious Process
Enterohinal Cortex
1) Major input into hippocampus
Hippocampus
Memory formation
-memory is laid down here first
Septal Area
Pleasure center
-strong connection to Nucleus Accumbens
NT involved in Pleasure Complex/Addiction
1) Dopamine
2) Endorphins-opoid
3) Enkephlin-opoid
4) Serotonin
5) GABA
Opiate Agonist
1) Endorphin
2) Enkephaline
Opiate Antagonist
1) Naltrexone
- used for alcoholic to take the pleasure out of drinking
Basal Nucleus of Meynert (BNM)
1) AKA substantia innominata
2) emotion, motivation, and memory
3) sends Ach efferents throughout the cortex
4) Degenerates with Alzheimers->basis for memory loss
Nucleus Accumbens
1) Addiction
2) dopamine receptors
3) Drugs like cocaine enhance dopamine activity in nucleus
Septal Nuclei
1) Pleasure Center/Addiction
2) strong dopaminergic input
3) When stimulated-euphoric feeling/orgasm
Ventral Tegmentum Area (VTA)
1) Found in midbrain
2) Pleasure center/addiction
3) Dopamine as NT
4)Dopamine projects to:
-Nucleus Accumbens
-Limbic system
-prefrontal cortex
-insular cortex
&project back to VTA
5) major center for addiction
Nicotine
1) most addictive chemical substance
2) works w/ Nucleus Accumbens
Fornix
1) some of the fibers connect to:
- hippocampus
- mammilary bodies
2) some fibers go into:
- hippocampal commisuri
- connecting to other side
3) Afferent and Efferent fibers found here
Fimbria of hippocampus
1) Major efferent pathway
- goes through fornix
- major targer=mammilary bodies
Amygdala location
slightly anterior to hippocampus
Mammillary Bodies Fxn:
Memory Formation
Major vs Minor Afferents: Hippocampus
CHASE U
1) Cingulate gyrus
- higher cortical areas->cingulate gyrus->entorhinal cortex-> hippocampus
2) Entorhinal Cortex
- major input into hippocampus
3) Amygdala
4) Hypothalamus via fornix
5) Septal Area via fornix
6) Uniculate Fasciculus
- tract from frontal cortex to temporal lobe
- minor input to hippocampus
Major vs minor Efferents: Hippocampus
FANTHEMS
1) Frontal Cortex
2) Nucleus Accumbens
3) Septal Nucleus
4) Mammilary Bodies
5) Thalamus-Anterior Nucleus
6) Amygdala
7) Hypothalamus
8) Entorhinal Cortex
Cingulate Gyrus
-function
1) Important role in maternal behavior
Left Anterior Cingulate Gyrus Lesion
1) Right side emotional facial paralysis
-interferes w/limbic connection w/facial nerve
(blank Face)
-CN7stays intact
CA
Pyramidal Cells of hippocampus
Dentate Gyrus
Granule cells=neurons
Entorhinal Cortex
1) major afferent pathway to hippocampus
2) minor efferent pathways
Subiculum
1) associated with the hippocampus
2) sends efferents via entorhinal cortex and fimbria
Afferent fibers tract into hippocampus
1) Afferent fibers tract into hippocampus
2) Synapse on dentate gyrus-> pyramidal neurons->
3) Pyramidal neurons send info out by:
- subiculum (mostly)
- fimbria
Papez circuit
1) AKA Mammallothalamic tract
2) Sustains Mood and emotion
3) Once tract is going hard to stop
- own momentum
- why we can’t snap out of mood
4) Septal Nuclei Not involved
Major Afferents: Amygdala
No Smoking On The Hammocks Because THC
1) Nucleus of Stria terminals
2) Septal Nucleus
3) Olfactory
4) temporal lobe
5) Hippocampus
6) Brain stem nuclei
7) Thalamus
8) Hypothalamus
9) Cingulate Gyrus
Travel through Stria Terminals NOT FORNIX
Major Efferents: Amygdala
Students Never Smoke THC Because of Hippies
1) Substantia Innominata
2) Nucleus Accumbens
3) Septal Nucleus
4) Brainstem Nuclei
5) Hippocampus
6) Hypothalamus
7) Thalamus
8) Caudate and Putamen
Ventral Amygdala fugal tract=major tract out
Amygdala 2 major tracts
1) Stria Teminalis
- major afferent
2) Bentral Amygdala Fugal Tract
- major efferent
Major Afferent tract to Habenula
1) Stria Medullaris Thalami
Major Efferent tract from Habenula
1) Habenulointerpeduncular Tract
- travels within the dorsal longitudinal fascicles to various parts of brain
Stria Terminalis
1) located on top of the thalamus
- goes lateral and then inferior to amygdala
2) Bilateral
Stria Medullaris thalami
1) links habenula to amygdala
2) Bilateral
Habenula Tract
1) Striamedullaris of thalami-> Stria Terminalis-> Amygdala
2) Projects to brainstem
Amygdala
-function
Part of limbic System; bilateral-base emotion
1) stimulation
-increase or decrease heart rate and Blood pressure depending on which nucleus
-Base emotion-arousal, aggression, and attack behavior
Sexual Desire-erection, ejaculation, orgasms, copulatory movements, and ovulation
-rhythmic movement-eating/chewing
-defensive
2) Contains many nuclei
3) highest density of receptors for sex hormones
Bilateral Amygdala lesion
1) gets rid of natural occurring fear response
Working Memory
1) Short term memory, not stored
- mins
2) lateral Prefrontal Cortex
- -not hippocampal function
Hippocampus
1) Declarative memory
- learning nonprocedural/motor tasks
ex: learning neuro notes
2) memories are stored
- months to few years
3) long term memories
- not stored here but in various parts of cortex
Damage to Hippocampus
1) cannot learn anything new
2) still remembers long term memories
- ex: name bc they are stored somewhere else
What are the 3 types of memory
1) Declarative
- learning notes (hippocampus)
2) Procedural
- how to tie shoes (not hippocampus)
3) Emotional
- amygdala (not hippocampus)
2 types of long term memory
1) episodic narrative
- humans are wired to remember sortes
- stories stick to us
2) Semantic Facts:
- ex: history dates
- 1492columbus sailed the ocean blue
Medial Geniculate
1) Nuclei of thalamus
2) Processes auditory
Fear conditioning Experiment
- initial experiment
- condition/uncondition
- results
- tract
1) Tone and Foot shock
-freezing fear response in rat
2)
Foot shock=unconditioned stimulus (US)
Tone=Conditioned Stimulus (CS)
Fear= Conditioned Response (CR)
3) Results:
-does not involve the auditory cortex
-thalamus-amygdala connection necessary
-ablation of medial geniculate eliminated fear conditioning
4) Tract
Ear-> Medial Geniculate of thalamus:
1) Auditory cortex- conscious appreciation of sound
2) Amygdala-emotional response to sound
Edouard Claparede
1) pt could not form new memories
-Bilateral hippocampal lesion
2)Fear Conditioned
-didn’t recognize doctor, taped tack to palm to shake
hand
-after a few wouldn’t shake hand-didn’t know why
3) Absence of Declarative memory BUT NOT EMOTIONAL MEMORY
-not hipppocampal dependent
H.M
1) pt w/both hippocampus removed due to epilepsy
2) ANTEROGRADE MEMORY DEFICIT
- no new memories
- severe
3) RETROGRADE MEMORY DEFICIT
- recalling old memory (long term memory)
- mild
4) Did have Procedural Memory
- ability to perform motor skill tasks (drawing a star)
Development of Memory in children
1) Before age of 3
- amygdala fully developed when born
- hippocampus circuit not fully developed until 2-3y.o
2) emotional memories before declarative memories in development
Westermarck Effect
1) Gut instinct of moral wrongness without reason
- believe morally wrong to have sex with sister
- not genetic
- evolutionary advantage to allow genetically variable and decrease genetically recessive diseases
How do we change out morals or mind?
1) Personal Life experience
- food stamps example
Propanolol
1) Non selective beta blocker
- beta adrenergic blocking
2) Blocks adrenaline(sympathetic response) during PTSD episodes, so they don’t remember it
3) manages:
- agina pectoris
- hypertension
- congestive heart failure
Flashbulb memories
- 9/11
- traumatic car crash
1) 9/11/2001
- amygdala turns on sympathetic nervous system
- Epinephrine, NE, adrenaline bathe hippocampus
- makes you remember everything after that
2) Adrenaline helps strengthen memories
3) IF amygdala too turn on TRAUMATIC CAR CRASH
- memories fail to form
- Anterograde Amnesia
- AMygdala->Hypothalamus-> Anterior Pituitary-> Adrenal Gland Large amounts of Cortisol
- Blocks or destroys declarative memories
PTSD
-Causes you to relive memories
-flashbulb memories
-brains are efficient to saving fear memories but hard to undo
Give Propanolol
Goal of psychotherapy for PTSD
1) teach neocortex to control the amygdala
- neocortex taps down impulses to fear memories
Wernicke-Korsakoff Syndrome
AKA Korsakoff psychosis -irreversible
1) Severe anterograde and retrograde amnesia
2) Caused by vitamin B1 (thiamine) deficiency
3) resulting from:
-malnutrition
-chronic alcoholism
4) Involves lesions in:
-dorsal medial thalamus
-mammilary bodies
-hippocampus
-frontal cortex
5) Symptoms:
-difficulting understanding written material
-conducting meaningful conversations
BC they forget what they just read or said
-ataxia
6) pts tend to confabulate
-take fragmented memories and make new reality
Kluver Brucy Syndrome
MPS VTAP
1) Bilateral loss of amygdala
2) Symptoms:
- hypermetamorphosis
- hyperorality
- hyperphagia
- hypersexuality (inanimate objects and either sex)
Agnosia:
- Visual
- tactile
- auditory
- placidity
Limbic system in ANS
1) Hypothalamus higher center of control for parasympathetic and sympathetic
2) parasympathetic
- brainstem and sacral
3) Sympathetic:
- T1-L2
4) Limbic also affects hormones secretion
Pseudobulbar affect PBA
1) AKA IEED-involuntary emotion expression disorder
- head injury or strok
- strong disconnect from facial emotion and what they are really feeling
ex: laughing at funeral
Addiction/Pleasure Centers
MAST
MEM/A/PAP
M: Basal Nucleus of Meynert -Ach -Memory -emotion -motivation A: Nucleus Accumbens: -Dopamine -Addiction S: Septal Nuclei -Dopamine -Pleasure Center T: Ventral Tegmentum Area -dopamine -Addiction and pleasure center
Hippocampal formation
1) Archicortex
2) composed of:
- subiculum
- hippocampus
- dentate gyrus
