Limbic system, etc. Flashcards
Mirror neurons
premotor and parietal cells (in ventral premotor and rostral inferior parietal lobe areas)
- fire similarly when self performs action OR watch action performed
- -> neurophysiological mech for imitation and empathy
Main structures of limbic system
- hippocampus and parahippocampal gyrus
- amygdala
- entorhinal cortex
- cingulate cortex
- prefrontal cortex
- septal nuclei
Autism and empathy
reduced activity shown in frontal lobe in response to facial expressions,
–> reduced empathy matched w/ reduced mirror neuron activity
Antipsychotic drugs
high binding affinity to dopamine D2 receptors = high effectivity,
1st gen: Chlorprozamine, haloprol
– side effects: sedation, hypotension
2nd gen: “Atypical” ie: clozapine (fewer side effects)
Antidepressant drugs
increase monoamine transmission by…
a) inhibit neuronal reuptake
b) inhibit degradation (enzymatic –> MAO-A/B)
Korsakoff’s Syndrome
Thiamine (B12) deficiency, = severe neurological disorder
* esp. in chronic alcoholism.
= damage to medial thalamus and mammillary bodies
–> amnesia, confabulation, apathy and decreased insight
Poikilothermic
= manner of body temperature regulation,
where change behavior to reach set pt temp.
(in reptiles and amphibians)
Cingulate Gyrus
responsible for motivation,
- Output to Hippocampus
- feedback Input from Anterior Thalamic nucleus
Prefrontal cortex
==> goal-directed behavior, moral reasoning and logical processing.
inhibits Amygdala.
Hippocampus
responsible for learning and memory (esp. declarative and spatial);
Input = from Cingulate gyrus
Output = to Septal nuclei and Mammillary bodies
Mesolimbic System
=> pleasure, addiction, euphoria, etc.
*uses Dopamine as NT, stimulated by cocaine and amphetamines
parts:
PFC, Amygdala, Hippocampus
amygdala
part of limbic system, for emotional memories;
* inhibited by Prefrontal cortex
Output: to Septal nuclei and Hypothalamus
Septal Nuclei
for reward and associative learning,
- lesion –> decreased fear conditioning
- associated w/ nucleus basalis of Meynert (& Alzheimer’s)
Hypothalamus
in limbic system: regulates stress,
* uses NE as NT*
input = from amygdala and septal nuclei
Output = to brainstem/spinal cord (+ Raphe nuclei)
Raphe Nuclei
= in brainstem and spinal cord,
* use serotonin (5-HT) as NT
anterior thalamic nuclei
in limbic system, –> alertness.
* feedback to cingulate gyrus
input = from mammillary bodies
Urbach-Weithe Disease
bilateral calcifications of Anterior Medial Temporal lobe and Amygdala;
- -> decreased emotional processing, loss of emotional memory,
- ** decreased fear conditioning!
Post-Traumatic Stress Disorder
increased activity in amygdala and hypothalamus bc decreased PFC activity.
–> hyperarousal, avoidance of similar situations, anxiety, flashbacks
Schizophrenia
–> enlarged lateral ventricles and cortical thinning,
= fragmented thought process, decreased emotional response.
+: delusion, hallucination
-: apathy, social withdrawal, decreased working memory and executive f(x)
Treatment: serotonin/dopamine R agonists
Major Depressive Disorder
decreased monoamine f(x) –> decreased activity of Ant. Cingulate gyrus and Septal Nuclei/Nuc. Accumbens
- MA gene modulation by CREB
treatment: MAO inhibitors, SSRIs (block reuptake), DBS
Alzheimer’s Disease
Hippocampal and PFC deficits, neurodegenerative
- amyloid plaques & neurofibrillary tangles (entire neocortical surface!)
- genetic (100%) if APP, PSEN1/2 mutations
- sporadic: increase risk if have ApoE2,3,4 polymorphism
- -> dementia, poor planning/spatial/judgement, change mood
Chronic Traumatic Encephalopathy (“CTE”)
from concussions/head trauma (to PFC and Cingulate cortex),
cortex shrinks and ventricles enlarge, increased tau deep in brain.
–> depression/suicide/mood disorders
posterior pituitary function
releases:
1. vasopressin –> vasoconstrict & increase H2O resorption
2. Oxytocin –> milk ejection, uterine contraction, sexual arousal/ejaculation
Anterior Pituitary Function
releases:
1. GH (I– somatostatin)
2. Prolactin (I– Dopamine)
3. TSH/FSH/LH
4. ACTH/B-endorphin
Diabetes Insipidus:
due to decreased vasopressin secretion,
Treatment: vasopressin analog that = anti-diuretic but Not vasoconstrictor;
Galactorrhea-Amenorrhea
disease: hyperProlactinemia + stop menstruating.
#1 cause: micro-adenoma in pituitary
–> increase prolactin, decrease LH and FSH
Treatment: 1. Dopamine R agonist
2. Surgery to remove tumor
