PT 22 LEC: Limbic System

key structures

thalamus, hypothalamus, amygdala, hippocampus

cerebral cortex

higher processing

basal strcutures

limbic connections

thalamus

main cortical

hypothalamus

homeostasis

amygdala & hippocampus

emotions & memory

major components of RAS

bulboreticular & thalamus

RAS system pathway

- activated via hormones

- either excitatory or inhibitory

- bidirectional

RAS NTM

ACh

slower background excitation in RAS

small conducting fibers; slower means greater memory

spinal cord

maintains antigravity tone

excitatory-activating system

- goes up to thalamus

- motor neuron activation

peripheral sensory activation

- going down

- pain causes strong excitation

cut above CN5

permanent coma

cut below CN5

facial & oral awareness preserved

RAS input sources

- cortex

- vestib

- cerebellum & BN

neurohormonal activation system

- hypothalamic & neurohypophysial systems

- NE, dopa, sero, ACh

- longer lasting than neural transmission

hypothalamic hormones

- released into hypophyseal portal system of hypothalamus; ANTERIOR PITUITARY

- passes thru infundibulum

neurohypophysial hormones

- from magnocellular neurons of hypothalamus; POSTERIOR pituitary

- passes thru infundibulum

pituitary tumor or hypothalamic lesions

affects entire body systems

HPA

- hypothalamic nuclei synthesizes hormones

- specialized BV travel

- ant. pituitary activation

- release into systemic circulation

neurohypophysial system

- magnocellular neurons produce hormones in hypothalamus

- axonal transport via infundibular stalk

- storage & release at post. pituitary

- systemic circulation target organ

hypophysiotropic hormones

- thyrotropin-releasing hormone

- corticotropin-releasing hormone

- growth-releasing hormone

- somatostatin

- gonadotropin-releasing hormone

- dopamine

- neurotensin

2 neurohypophysial hormones

- oxytocin; milk

- vasopressin; antidiuretic

adrenomedullary hormones

- adrenal medulla

- chromaffin cells

- NE, EPI, dopa, ACh

enterochromaffin cells

- digestive tract lumen

- histamine & serotonin

NE system

- ceruleus; pons & midbrain

- excitatory

- REM sleep & slee-wake cycles

- major stress hormone

dopamine system

reward-seeking

serotonin system

wellbeing, anxiety, sleep, pain control

ACh system

awake & excited

preoptic area

temperature regulation

lateral hypothalamus

thirst & hunger center

ventromedial nuclei

satiety sensation

periventricular nuclei emotion

fear & aggression

lat hypothalamus emotion

rage & fighting

ant/post hypothalamus

sex drive

punishment centers

- central gray around Sylvian aqueduct

- precedes over pleasure & reward

Kluver Bucy

affectation of amygdala