Thalamus and Hypothalamus Flashcards
thalamus
collection of subcortical grey matter and part of the diencephalon (along with the hypothalamus) involved in relaying information between different functional regions of the CNS
borders the dorsal part of the third ventricle and functions as part of the lateral wall of the ventricle
thalamic nuclei
relay, association, and nonspecific nuclei
relay thalamic nuclei
distinct inputs and outputs
includes: ventral posterior lateral (VPL) nucleus, ventral posterior medial (VPM) nucleus, lateral geniculate body/nucleus (LGN), medial geniculate body/nucleus (MGN), ventral anterior (VA) nucleus, ventral lateral (VL) nucleus
association thalamic nuclei
receive majority of their input from the cortex and project fibers to the other cortical regions
includes mediodorsal/dorsomedial nuclei, anterior nucleus, pulvinar
nonspecific thalamic nuclei
broadly project to numerous cortical regions
include reticular nucleus
ventral posterior lateral (VPL) nucleus
relay center for sensory information for the BODY
output is to the postcentral (sensory) gyrus
ventral posterior medial (VPM) nucleus
relay center for sensory information of the FACE
output is the postcentral (sensory) gyrus
VPM is also the relay center for taste
lateral geniculate nucleus (LGN)
relay center for vision. receives input from the retina with output to the primary visual cortex via optic radiations
optic radiations from the upper visual world travel through the temporal lobe and optic radiations from the lower visual world pass through the parietal lobe
medial geniculate nucleus (MGN)
relay center for hearing. receives input from the inferior colliculi and projects to the primary auditory cortex
ventral anterior (VA) nucleus
conveys motor information from basal ganglia to the premotor cortex
it plays a role in the initiation of movement
ventral lateral (VL) nucleus
conveys motor information from both the cerebellum and basal ganglia to the primary motor cortex
thalamic nuclei mnemonic
VPL: ‘very pretty LEGS’ (body)
VPM: ‘very pretty MOUTH’ (face)
LGN: ‘LOOKS good naked’ (vision)
MGN: ‘makes good NOISE’ (hearing)
mediodorsal/dorsomedial nuclei
receives input from the amygdala, subthalamic nucleus, and temporal lobe with output to the frontal cortex. it is involved in motivation and memory
lesions to mediodorsal nuclei
amnesia, behavioral issues, and executive dysfunction
anterior nucleus
receives input from the mammillary bodies with output to the cingulate gyrus. it is important for limbic function and memory formation
pulvinar
receives input from the superior colliculi as well as the association cortex and has outputs to many different regions in the cortex. it is involved in visual attention and is located in the posterior medial aspect of the thalamus
damage to the pulvinar
neglect and attention deficits
preferentially affected in patients with CJD
reticular nucleus
receives input from many cortical regions and projects directly onto other thalamic nuclei. it is the only thalamic nucleus that does not project to the cortex
thought to play a role in sleep-wake cycles
thalamic vascular supply
four major vessels:
- polar (tuberothalamic) artery
- paramedian (thalamic-subthalamic) artery
- thalamogeniculate (inferolateral) artery
- posterior choroidal artery -
polar (tuberothalamic) artery
originates from the posterior communicating artery (PCOM)
supplies anterior portion of the thalamus
anterior circulation stroke affecting thalamus
anterior circulation strokes can present with anterior thalamic involvement due to the polar artery arising from the PCOM - all other thalamic strokes arise from posterior circulatory system
lead to wide range of neuropsychiatric changes
paramedian (thalamic-subthalamic) artery
originates from the P1 segment of the posterior cerebral artery (PCA) and supplies the dorsomedial nucleus
infarction of paramedian (thalamic-subthalamic) artery
infarction has a range of neuropsychiatric symptoms
unilateral lesions can lead to language (dominant hemisphere) or visuospatial problems (non-dominant)
bilateral infarction can result in akinetic mutism. a top-of-the-basilar occlusion can commonly cause a bilateral infarction due to an anatomic variant known as the Artery of Percheron, where both paramedian arteries arise form a single pedicle on the P1 portion of PCA
posterior choroidal artery
arises from the P2 segment of the posterior cerebral artery (PCA)
supplies the lateral geniculate nucleus (LGN) and pulvinar among other nuclei
thalamogeniculate (inferolateral) artery
originates from the P2 segment of the posterior cerebral artery (PCA)
thalaMoGENICULATE artery supplies multiple nuclei including the Medial GENICULATE nucleus (MGN)
lesions to posterior choroidal artery
vision changes, variable sensory loss, weakness, and memory impairment
thalamic dysfunction can cause wide range of symptoms and syndromes
generally lesions to a nucleus of the thalamus lead to dysfunction of that relay arc (e.g. lesion of the VPL leads to numbness of the contralateral body)
Dejerine-Roussy Syndrome
thalamic pain syndrome
contralateral hemisensory loss of all modalities followed by body pain
akinetic mutism
can develop with thalamic lesions, presumably with the involvement of the reticular nucleus
can also be seen in bilateral prefrontal lobe lesions or caudate lesions as well
artery of Percheron stroke
vascular anatomic variant where one artery supplies both paramedian regions of the thalamus
clinically manifests with a decreased level of consciousness, hypersomnolence, aphasia/dysarthria, and oculomotor abnormalities
what restricts diffusion in thalamus on MRI brain
status epilepticus and cerebral hypoxic ischemic injury
hypothalamus
coordinating center of the endocrine system that helps maintain homeostasis containing several nuclei with various functions including autonomic function, body temperature regulation, and water balance
lateral nucleus of the hypothalamus
activates hunger/thirst
lesion: aphagia/adipsia
medial preoptic nucleus of the hypothalamus
releases gonadotropic releasing hormone (GnRH)
anterior nucleus of the hypothalamus
temperature regulation
lesion: hyperthermia
supraoptic and paraventricular nuclei of the hypothalamus
produces ADH and oxytocin (stored and released by posterior pituitary)
lesion: diabetes insipidus and impaired lactation
suprachiasmatic nucleus (SCN) of the hypothalamus
circadian (24hr) pacemaker
ventromedial nucleus (VMN) of the hypothalamus
satiety center
lesion: hyperphagia
dorsomedial nucleus of the hypothalamus
aggression
lesion: may lead to docility
posterior nucleus of the hypothalamus
heat conservation
lesion: poikilothermia
mammillary bodies
memory formation
poor long term memroy formation
