Thalamus Flashcards
the part of the diencephalon that gates the input of sensory and motor information from subcortical areas to specific cortical areas; crucial for conscious awareness
thalamus
separates the medial and lateral thalamus
internal medullary lamina
basal ganglia relay in the thalamus
ventral anterior nucleaus (VA)
cerebellar relay in the thalamus
ventral lateral nucleus (VL)
the two nuclei that constitute the motor thalamus
ventral anterior (VA) and ventral lateral (VL) nuclei
nucleus that receives the (contralateral) spinothalamic and medial lemniscus inputs from the body
ventral posteriolateral nucleus (VPL)
the part of the thalamus that consists of the medial and lateral geniculate, which relay auditory and visual information to the cortex
pulvinar
type of thalamic nuclei that have reciprocal cortical connections and are important for the maintenance of spatial organization of inputs (e.g., retinotopy, somatotopy, musculotopy)
specific thalamic nuclei
type of nuclei that are diffuse and have multimodal sensory inputs, are largely non-reciprocal with the cortex, and get strong input from the reticular formation (behavioral arousal and consciousness)
non-specific thalamic nuclei
the VPL outputs limb and trunk somatosensory information to what part of the cortex?
postcentral gyrus
nucleus that transmits somatosensory information from the trigeminothalamic system to the face portions of the postcentral gyrus
ventral posteriomedial nucleus (VPM)
portion of the VPM that receives taste information from the NTS and is reciprocally connected with the anterior part of the insula (primary gustatory cortex)
parvicellular (VPMpc)
Receives visual input via the optic tract, representing the contralateral visual field
lateral geniculate nuclei (LGN)
projections from layers III-VI of the lateral geniculate nucleus that convey fine details about form and color from retinal cones
parvocellular projections
projections from layers I and II of the lateral geniculate nucleus that convey information about movement, depth, and small differences in brightness from retinal rods
magnocellular projections
inputs from the temporal and nasal retina end in what layers of the lateral geniculate nucleus?
temporal: layers 2,3,5
nasal: layers 1,4,6
receives auditory input from the inferior colliculus
medial geniculate nucleus (MGN)
nucleus that is reciprocally connected with primary visual cortex (V1) on the banks of the calcarine fissure in the occipital lobe
lateral geniculate nucleus (LGN)
nucleus that is reciprocally connected with the auditory cortex in Heschl’s gyrus of the temporal lobe
medial geniculate nucleus (MGN)
the ventral lateral nucleus (VL) and ventral anterior nucleus (VA) are targeted by this common input bundle, carrying crossed cerebellothalamic fibers from the cerebellum, and uncrossed pallidothalamic fibers from the basal ganglia
thalamic fasciculus
thalamic nucleus that receives crossed output of cerebellar deep nuclei (dentato-rubro-thalamic pathway) via the thalamic fasciculus
ventral lateral nucleus (VL)
thalamic nucleus that receives segregated inhibitory input from the ipsilateral basal ganalia via the thalamic fasciculus, allowing you to perform automated, previously-learned movements
ventral anterior nucleus (VA)
the ventral anterior nucleus (VA) is divided into two parts, each receiving inputs from the basal ganglia: the lateral part receives input from _______ and the medial part receives input from ________.
globus pallidus internal segment (GPi);
substantia nigra pars reticulata (SNr)
Effects of basal ganglia disease on motor function are expressed ________
because the lateral CST crosses in the medulla
contralaterally
Effects of cerebellar disease are expressed _____, because the motor cortex (via VL) receives crossed cerebellar inputs, but the output (lateral CST) crosses back in the medulla.
ipsilaterally
________ nuclei receive input from many thalamic nuclei and have non-reciprocal connections with the cortex, which allows for complex integration of stimuli in
different sensory domains; examples include mediodorsal nucleus (MD) and pulvinar
association
a type of association nucleus in the thalamus that relays inputs from the basal forebrain to the limbic system and prefrontal cortex; plays crucial role in attention, planning, organization, abstract thinking, multi-tasking and active memory
mediodorsal nucleus (MD)
complex structure that receives input from the retina, superior colliculus and (indirectly) from the spinothalamic tract; lesions here affect language processesing, visual perception, and pain perception
pulvinar
nucleus with uncertain function that works in concert with the pulvinar
lateral posterior nucleus (LP)
nuclei that receive input from parahippocampal region through the fornix, and mammillary bodies via the mammillothalamic tract; has densest cholinergic input from the midbrain and projects to the cingulate gyrus
anterior group (AN) nuclei
feedback pathway that is primarily engaged in transfer of information from short-term to long-term memory
papez circuit
nucleus that receives input from parahippocampal region via fornix and acts in concert with the anterior nuclei of thalamus; relays spatial information to the parietal and retrosplenial cortices
laterodorsal nucleus (LD)
severe degerenative changes in the anterior group of nuclei found in alcoholics with amnesia
korsakoff’s syndrome
non-specific thalamic nuclei that mostly receive pain-related information from midbrain PAG, as well as strong inputs from locus ceruleus (NE) and midbrain raphe (5-HT); believed to be involved with general cortical arousal
midline nuclear group
group of thalamic nuclei that receive strong cholinergic input from ARAS; lesions of this nucleus lead to unilateral motor neglect, so it is thought to be involved in attention to motor tasks
intralaminar group of nuclei (including centromedian nucleus)
Thalamic relay neurons are usually relatively hyperpolarized in a “de-inactivated” ____ mode, which is generally less able to pass an incoming signal to the cortex, but maximizes initial stimulus detection.
burst
these thalamic cells are GABAergic and hyperpolarize thalamic relay neurons, leaving them primed for bursting activity
intralaminar cells
these cells lie outside of the external medullary lamina, encasing the thalamus like a shell, and use GABAergic signalling to switch the thalamocortical neurons from burst mode to single-spike tonic mode (which makes the thalamus capable of passing a signal on)
thalamic reticular nuclei (TRN)
large, boomerang shaped tract of white matter carrying ascending and descending fibers to and from the cortex
internal capsule
blood supply to the thalamus is mostly from what artery?
PCA
