23.2 Thalamus Flashcards
What is the primary function of the thalamus?
To relay motor and sensory signals to the cerebral cortex
Where in the brain is the thalamus located?
At the core of the diencephalon, deep to the cerebral cortices
Which three main parts is each half of the thalamus divided into?
Anterior, medial, lateral
Which structure partitions the anterior, medial and lateral thalami?
Internal medullary lamina
Which structure connects the left and right halves of the thalamus?
Interthalamic adhesion
What is the afferent and efferent supply of the LGN (vision)?
Afferent - optic nerves
Efferent - V1
What is the afferent and efferent supply of the MGN (auditory)?
Afferent: inferior colliculi
Efferent: A1
What is the afferent and efferent supply of the pulvinar nuclei (visual attention)?
Afferent: superior colliculi
Efferent: V1, PPC (posterior parietal cortex), PFC (prefrontal cortex)
What is the afferent and efferent supply of the ventral anterior (VA) nuclei?
Afferent: basal ganglia
Efferent: premotor cortex
What is the afferent and efferent supply of the ventral lateral (VL) nuclei?
Afferent: basal ganglia AND cerebellum
Efferent: premotor cortex AND primary motor cortex
What is the afferent and efferent supply of the VPL? (ventral posterior lateral)
Afferent: Dorsal column system AND anterolateral system
Efferent: S1
What is the afferent and efferent supply of the VPM?
Afferent: trigeminal nerve (sensory), NTS (taste)
Efferent: S1
What is the afferent and efferent supply of the anterior nuclei (limbic)
Afferent:
*Mammillary bodies
*subiculum (part of hippocampus)
Efferent:
*Cingulate gyrus
What is the difference between primary (first order) thalamic nuclei and higher order thalamic nuclei?
Primary nuclei process info from peripheral sensory inputs
Higher order nuclei process info from the cortex (layer V)
With what structure does the thalamus have reciprocal connections with?
Cortex. Thalamus sends afferent to cortex.
How is the thalamus arranged?
topographically.
How is the topographical organisation and reciprocal connections with cortex beneficial?
this provides an effective, gated switchboard system that allows certain information to be better condensed and pass through following parallel processing, decreasing the cortical processing power required and accelerating the interpretation of information at the same time as reducing the necessary cortical volume
What is the function of the anterior nucleus?
Helps to control the generation of memories, and influences alertness
What is the function of the ventral anterior nucleus?
Receives afferent inputs from the GPi/SNr of the basal ganglia system, providing the inhibitory signal that (at baseline) gates the release of movements from the premotor cortex to improve selection of appropriate, internally-generated movements
What is the function of the ventral lateral nucleus?
coordination of movements
What is the function of ventral posteromedial nucleus?
allowing the relay of tactile information to S1
