thalamus and hypothalamus Flashcards
thalamic nuclei: explain the functional significance of the thalamic nuclei; explain the relationship between the intralaminar nuclei, reticular nucleus and the reticular formation
overall function of thalamus
relay site for numerous inputs/outputs
where is the thalamus a key relay centre to
cortical sensory areas (almost all sensory systems)
what sensory system is the thalamus not involved in
olfactory (smell)
what does the thalamus do to signals
modulatory so enhances or restricts
describe the somatosensory pathway
vibration, proprioception, light touch -> dorsal root ganglion -> dorsal horn -> posterior dorsal colum of spinal cord -> up to medulla via primary sensory neurone -> sensory decussation (crossing over) from gracile nucleus to cuneate nucleus (both posterior column nuclei; synapse present) -> up to thalamus via second sensory neurone -> enters and processed by thalamus at ventral posterior lateral nucleus -> enters primary somatosensory cortex (post-central gyrus in parietal lobe)
what do the intralaminar nuclei do
project to various medial temporal lobe structures
examples of medial temporal lobe structures innervated by intralaminar nuclei, location and relevant function
amygdala (frontal portion of temporal lobe; emotions, fear, anxiety), hippocampus (floor of ventricle of temporal lobe; memory), basal ganglia (movement, incl. control of initiation of movement)
where are the intralaminar nuclei located within the thalamus
line dividing thalamus anteriorly to posteriorly, just above the ventral posterior medial nucleus
what type of neurones are the intralaminar nuclei
mostly glutamatergic (excitatory)
what 2 diseases is loss of of neurones in intralaminar region associated with
Parkinson’s disease, progressive supranuclear palsy (PSP)
what does progressive supranuclear palsy (PSP) cause
rare brain disorder causing problems with walking and balance
what does the reticular nucleus form
outer covering of thalamus
what type of neurones is the reticular nucleus
GABAergic (inhibitory)
what do reticular nucleus neurones conect with
other thalamic neurones, not distal regions (like other thalamic nuclei)
where does the reticular nucleus receive inputs from
collateral of their axons from other thalamic nuclei (so further on than dendrites, so modulatory)
