B7.061 Thalamus and Hypothalamus Flashcards
function of the thalamus
last synaptic relay station in ascending pathways before they reach the cerebral cortex
“gateway to the cerebral cortex”
contains specific and diffuse projection nuclei
how are the thalamus and cortex connected
reciprocally
embryonic origin of thalamus
diencephalon (along w hypothalamus)
function of internal medullary lamina
fiber bundle that divides the thalamus into 3 regions 1. medial 2. lateral 3. anterior also contains intralaminar nuclei
lateral nuclear group
ventral anterior lateral dorsal ventral lateral lateral posterior ventral posterior lateral ventral posterior medial lateral geniculate medial geniculate pulvinar
how do thalamic nuclei receive input
from specific subcortical regions
input to anterior nucleus
mammillothalamic tract
fornix
input to ventral anterior
motor nuclei:
substantia nigra pars reticulata
internal globus pallidus
deep cerebellar nuclei
input to ventral lateral
motor nuclei:
internal globus pallidus
deep cerebellar nuclei
substantia nigra pars reticulata
input to ventral posterior lateral
somatic sensation of body:
medial lemniscus
spinothalamic
input to ventral posterior medial
somatic sensory of face:
trigeminal lemniscus
trigeminothalamic tract
gustatory input
input to lateral geniculate
optic tract
input to medial geniculate
inferior colliculus
input to pulvinar
multisensory:
superior colliculus
tectum (extrageniculate visual pathways)
other sensory inputs
input to intralaminar nuclei
internal globus pallidus
brainstem reticular formation
sensory pathways
input to medial group
amygdala
olfactory cortex
basal ganglia
output of anterior nucleus
cingulate gyrus (Papez circuit)
output of ventral anterior
frontal cortex
output of ventral lateral
motor and premotor cortex
output of ventral posterior lateral
somatosensory cortex
output of ventral posterior medial
somatosensory cortex
output of lateral dorsal
cingulate gyrus (Papez circuit)
output of medial group
prefrontal cortex
output of intralaminar nuclei
widespread cortical region
output of pulvinar
parieto-occipital cortex
output of medial geniculate
auditory cortex
output of lateral genicular
visual cortex
function of ventral posterior lateral
relays somatosensory spinal inputs to cortex
function of ventral posterior medial
relays somatosensory cranial nerve inputs and taste to cortex
function of lateral geniculate
relays visual inputs to cortex
function of medial geniculate nucleus
relays auditory inputs to cortex
function of ventral lateral nucleus
relays basal ganglia and cerebellar inputs to cortex
major motor relay nucleus between the cerebellum and primary motor cortex
thalamic portion of cerebellar feed forward system for smoothing out movements
function of ventral anterior nucleus
relays basal ganglia and cerebellar inputs to cortex
more widespread projections than ventral lateral
receives input from the BG and projects widely to the frontal eye fields and premotor cortex in the frontal lobe
which thalamic nuclei are part of limbic circuits
anterior nucleus mediodorsal nucleus (medial group)
function of mediodorsal nucleus
limbic pathways
major relay to frontal cortex
function of anterior nucleus
limbic pathways
function of pulvinar
behavioral orientation to relevant visual and other stimuli
function of intralaminar nuclei
maintain alert consciousness
motor relay for basal ganglia and cerebellum
where is the reticular nucleus
anterior area
input to reticular nucleus
cerebral cortex
thalamic relay and intralaminar nuclei
ARAS
output of reticular nucleus
thalamic relay and intralaminar nuclei
ARAS
no cortical projections!! modulates other nuclei in the thalamus
function of reticular nucleus
regulates state of other thalamic nuclei
functions of hypothalamus
homeostasis
endocrine
autonomic
limbic
rostral to caudal components of the hypothalamus
preoptic area
anterior (supraoptic) region
middle (tuberal) region
posterior (mammillary) region
structure of the pituitary gland
anterior and posterior component
both components controlled by the hypothalamus separately
neurohypophyseal system
direct control of posterior pituitary by hypothalamus
neurons from supraoptic and paraventricular nuclei
release oxytocin and vasopressin deep within the posterior pituitary
tuberoinfundibular system
indirect control of anterior pituitary by hypothalamus
neurons of arcuate and periventricular nuclei release releasing factors that act on anterior pituitary cells
why are there 2 lobes of the pituitary
distinct embryological origins
Rathke’s pouch > anterior
infundibulum > posterior
homeostatic functions of the hypothalamus
temperature regulation
feeding behavior
circadian rhythm
thirst/ body fluid
how is temperature information conveyed to hypothalamus
- somatosensory system; temp sensitive afferents
2. neurons in the anterior nucleus of the thalamus sense temp
how is the body response to change in temperature coordinated
anterior nucleus of hypothalamus: response to warm
posterior nucleus of hypothalamus: response to cold
change in body temp set point (fever)
hypothalamic neurons activated in the pre-optic area
activation of septum can reduce fever
function of ventromedial hypothalamic nucleus
satiety
stimulation reduces food intake
lesions produce overeating and obesity
function of lateral hypothalamic nuclei
feeding center
stimulation produces eating
lesions produce anorexia
leptins
produced in adipose tissue
reduce appetite
ghrelin
produced in gastric mucosa
stimulates appetite
regulation of circadian rhythm
suprachiasmatic nucleus receives input from retinal ganglion cells containing melanopsin
regulates core body temp, ACTH levels, slow wave sleep, and skin temp
thirst/ body fluid regulation
ADH (vasopressin) release by supraoptic nucleus
anterior nucleus involved in coordinating drinking behavior
autonomic functions of the hypothalamus
descending control of preganglionic parasympathetic and sympathetic neurons comes for the paraventricular nucleus of the hypothalamus
functions of the limbic system
homeostasis
olfaction
memory
emotions and drives