Thalamus Flashcards
Important sensory modality which does not use the thalamus.
Smell
Function of thalamus
Receives sensory and motor information and passes it to different sections of the brain– primarily the cerebral cortex. Also functions in regulation of consciousness, sleep and alertness. Filters what information is important, though it does not function on its own.
The cortex will use this info to affect the cerebellum, and the basal ganglia
General role of cerebellum
Pays attention to what you want to do, and makes sure that’s what you actually are able to do (ex. to touch your nose– makes adjustments to make sure you can do this)
General basal ganglia function
Coordination of motor activity between agonist and antagonist muscle (makes sure agn. contracts and antag. shuts off)
Most of the thalamic neurons are…
Projection neurons
Most of the information which directly enters the thalamus is…
Sensory/ regulatory
Thalamus is also known as the…
Diencephalon
Divisions of the Diencephalon.
- Epithalamus
- Dorsal thalamus
- Subthalamus
- Hypothalamus
Main lamina/nuclei associated with Dorsal thalamus
- Internal medullary
- Intralaminar
- Thalamic reticular
Information entering and leaving the thalamus moves through…
The reticular nuclei
What foramen is near the tip of the thalamus?
The tip of the thalamus is right at the junction of the interventricular foramen, connecting lateral ventricle to the 3rd.
What shape is the caudate nucleus and where does it get information from?
C-shaped– gets information from many different parts of the brain.
Three (3) functional groups of the thalamic nuclei.
(1) Specific/relay nuclei
(2) Association nuclei
(3) Non-specific nuclei
Specific/relay nuclei
- Well defined sensory inputs such as hearing and vision
- Lots of topographic/somatotopic input– information synapses based on where it comes from.
Association nuclei
These receive feedback from parts of the cortex which process the original sensory information.
Ex.) Your eyes see things, but in order to interpret them and do higher level analysis, the association nucleus is needed.
Pulvinar Thalami
Gets information from parietal lobe and posterior association areas
Non-specific nuclei
- Form 2 main groups- intralaminar and thalamic reticular
- function in alertness, awareness and cognitive function. “Awakens” the cortex.
Reticular nucleus of thalamus
THIS IS NOT PART OF THE RETICULAR FORMATION
Control flow of information in and out of thalamus. Think of it as filter or screen, with parts opening and closing depending on what information is needed at a given time. Enhances needed info, inhibits random info.
Thalamic peduncles
Large bundle tracts which serve as projections from the thalamus
(Superior, Posterior, Anterior and Inferior)
Fibers leaving from the thymus go via what path?
Posterior, Anterior or Genu of internal capsule, depending on what part of the cortex they’re going to.
VA/VL (ventral anterior/ventral lateral)
An important thalamic nucleus
Pass info from Basal ganglia to motor areas of cortex- precentral gyrus
And vice versa
VPL (ventral posterolateral)
An important thalamic nucleus
Pass info from medial lemniscus/spinothalamic (spinal components) tract to somatosensory cortex- postcentral gyrus
And vice versa
VPM (ventral posteromedial
An important thalamic nucleus
Pass info from medial lemniscus spinothalamic tract (trigeminal components) to Somatosensory cortex- postcentral gyrus
And vice versa
Medial geniculate
An important thalamic nucleus
Passes info from brachium of the inferior colliculus to the auditory cortex (transverse temporal gyri)
And vice versa
Lateral geniculate nuclei
An important thalamic nucleus
Passes info from Optic tract to the visual cortex (occipital lobe)
And vice versa
Anterior nuclei
An important thalamic nucleus
Passes info from mammilothalmic tract to the cingulate gyrus.
And vice versa
Blood supply to thalamus comes from…
Small perforating arteries (which come off predominantly the POSTERIOR CEREBRAL ARTERY)
A bleed here would affect the sensory aspects of the other side of the body.
Most of the specific inputs to the thalamus use _____ as a neurotransmitter.
Glutamate
Intralaminar nuclei
Project to both the cerebral cortex and basal ganglia
What is unique about the thalamic reticular nucleus?
It projects to other thalamic nuclei, NOT the cerebral cortex
