Thalamus II Motor to Cognitive- Burke Flashcards
Auditory system entails several parallel pathways and information for each ear reaches both sides of the system even at the level of the brainstem
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Medial geniculate
a SPECIFIC thalamic nucleus (driven by auditory input coming from the outside) that is the stop before the cortex
What are the
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Lateral geniculate nucleus
- sends axons via optic radiations
- projections from the retinal nucleus striated pathway
- within the nucleus we have 6 layers
magnocellular are big are for motion and spatial analysis (layer 1 and 2)
parvocellular are small and for form and color (layers 3-6) ????
layer 1 is contralateral layers 2, 3, 5 are ipsilateral
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- Magnocellular will have large center surround receptive fields
- Parvocellular will have smaller receptive field for sharper
Koniocellular project to layers 2,3 of the primary visual cell cortex; have the smallest cell bodies; have strong color sensitivity
When Auditory becomes Visual, a thalamic role in cross-modal plasticity?
LGN will receive projections from the retinal ganglion cells from the optic nerve. This will drive the LGN (outside stimulus) and repel other projections from coming in.
What happens with someone congenitally blind or deaf?
Auditory becomes Visual, a thalamic role in cross-modal plasticity
cross-modal plasticity in specific auditory cortices underlies visual compensation in the deaf
You see with the visual cortex not your eyes. You hear with your brain not your ears.
blind person has really high contrast
Where are modulatry goals?
layers 6
Pulvinar plays an important role in the higher processing of the cortex???
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Motor Nuclei VL, VA, VI
-Basal Ganglia
-Cerebellum
Modulation and coordination of movement
Initiation and planning of movement
Coordination of movement
Cognitive function?
Basal Ganglia circuitry???
-gives GABAergic output to the thalamus
What are the four loops that go through the basal ganglia?
- motor loop
- limbic loop
- cognitive loop
- oculomotor loop
Subthalamic nucleus
is the only part of the midbrain that is purely glutamatergic (Excitatory)
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super important for midline cognitive functions???
Anterior Nuclear Group Lateral Dorsal (LD)
have reciprocal connections with mammillary bodies and cingulate gyrus
hippocampus
is spatial navigation knowing where you are in the environment
Drivers vs. Modulatories
1st order thalamic relay: direct senory information driving into it
driven by layer 6?????
Pulvinar ???
is not a homogeneous region has its own architecture and subdivisions
has reciprocal connections with frontal orbital cortex
Pulvinar-LP Complex
plays a role in being able to pay attnetion
Autism all have r
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intralaminar nuclei looks like a Y
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Reminder of acoustic pathway:
Inputs for hearing and vestibular sense (CN VIII) reach the cochlear and vestibular nuclei, respectively. After entering the brainstem, the hearing pathways decussate at multiple levels. Auditory information ascends in the lateral lemniscus to reach the inferior colliculus. From there, fibers ascend via the brachium of the inferior colliculi to the medial geniculate nuclei of the thalamus, located just lateral to the superior colliculi of the midbrain. Information then continues in the auditory radiations to the primary auditory cortex.
Auditory system entails several parallel pathways and information for each ear reaches both sides of the system even at the level of the brainstem.
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What is the function of the medial superior olive (MSO)?
computes the location of sound by interaural time differences
What is the function of the lateral superior olive (LSO) and medial nucleus of the trapezoid body (MNTB)?
computes position of a sound source through interaural intensity differences
List aspects of the lateral lemniscus.
- contralateral side responds to sound arriving at one ear only- monaural
- signal onset of sound regardless of intensity or frequency
- process aspects of sound such as duration
What is the function of the medial geniculate?
the obligatory relay for all ascending auditory information destined for the cortex
What is the major thalamocortical relay?
the ventral division
What is the midbrain auditory center?
inferior colliculus
What is the function of inferior colliculus?
- receives ascending auditory pathways via the olivary and lemniscal complexes and others that arise directly from the cochlear nucleus
- process sounds with complex temporal patterns
What are the division of the medial geniculate?
ventral, medial, and dorsal divisions
What is the first station in the auditory pathway where pronounced selectivity for combination of frequencies are found?
medial geniculate
Describe the input into the medial geniculate.
most input arises from inferior colliculus but some bypass the internal capsule
The lateral geniculate nucleus is composed of six layers, numbered from ventral to dorsal. What is the ventral and dorsal pathway?
ventral pathway: parvocellular
dorsal pathway: magnocellular
What kind of input and output do the parvocellular layers have?
INPUTS from retinal ganglion midget cells and send OUTPUTS to visual cortex layer 4Cbeta.
What kind of input and output do the magnocellular layers have?
INPUTS from retinal ganglion parasol cells and send OUTPUTS to visual cortex layer 4Calpha.
The lateral geniculate nucleus sends axons to the cortex via what?
optic radiation of the internal capsule
-this is known as retinogeniculostriate pathway
What layers and functions are associated with magnocellular, parvocellular, and koniocellular pathway?
magnocelular: in layers 1 and 2; motion and spatial analysis
parvocellular: in layers 3-6; detailed form and color
Koniocellular project to layers 2 and 3 of the primary visual cell cortex; have the smallest cell bodies; have strong color sensitivity (stronger than parvocellular)
lateral geniculate nucleus is a relay center in the thalamus for the visual pathway.
Compare the receptive fields and response to stimuli of magnocellular and parvocellular.
Magnocellular: larger receptive fields; respond transiently to the presentation of stimuli
Parvocellular: small receptive fields; respond to sustained fashion, transmit information about color
Auditory projections from the brainstem are going to go to the MGN and will give off chemorepulsive signals to other neurons .
Lateral geniculate nucleus (LGN) is driven by the visual system and will receive retinal ganglion cells.
What occurs in blindness and deafness?
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