29 - Thalamus Flashcards
1
Q
Thalamic Nuclei Categories
A
- “Specific” thalamic nuclei
- Reciprocally connected with specific cortical areas
- Maintenance of spatial organization (retinotopy, tonotopy, somatotopy, musculotopy) of inputs
- “Non-specific” thalamic nuclei
- Diffuse and multimodal sensory inputs
- Diffuse and largely non-reciprocal innervation of cortex
- Strong input from reticular formation
2
Q
Ventral Posteromedial Nucleus (VPM)
A
- INPUT: trigeminothalamic system
- OUTPUT: Somatosensory cortex (reciprocal)
- VASCULATURE: Inferolateral vessels (PCA)
- FUNCTION: face somatosensory
- LESION: contralateral hemianesthesia
Also, taste info from CNs 7, 9 > rostral NTS > (via dorsal longitudinal fasciculus) > VPMpc > insula
3
Q
Ventral posterolateral nucleus (VPL)
A
- INPUT: STT, DCML (pain/temp, touch)
- OUTPUT: Somatosensory cortex (reciprocal)
- VASCULATURE: Inferolateral vessels (PCA)
- FUNCTION: Somatosensory from limbs, trunk
- LESION: contralateral hemianesthesia
4
Q
Ventral lateral nucleus (VL)
A
- INPUT: crossed cerebellar deep nuclei (from dentate nucleus, SCP) via thalamic fasciculus
- OUTPUT: Primary motor cortex (reciprocal) M1
- VASCULATURE: Inferolateral vessels (PCA)
- FUNCTION: neuron firing timing
- LESION (to cerebellum): ipsilateral motor control
- (corticospinal tract crosses in medulla)
Dentate nucleus > superior cerebellar peduncle > crosses midline in midbrain > VA thalamus of opposite side > M1 to change rate code
5
Q
Ventral Anterior Nucleus (VA)
A
- INPUT:
- Ipsilateral inhibitory BG (GPi, SNr) via thalamic fasciculus
- Lateral: ipsilateral GPi
- Medial: ipsilateral SNr
- OUTPUT:
- Lateral: Premotor cortex
- Medial: premotor cortex, FEFs, cingulate/parietal cortices
- VASCULATURE: Inferolateral vessels (PCA)
- FUNCTION:
- Lateral: motor initiation for trunk, limb
- Medial: motor initiation of eye, head, neck
- LESION (to BG): contralateral motor deficit
- Because corticospinal tract crosses in medulla
6
Q
Medial Geniculate Nucleus (MGN)
A
- INPUT: inferior colliculus (auditory input) via inferior quadrigeminal brachium
- OUTPUT: auditory cortex (reciprocal) in Heschl’s gryus via auditory radiations (sublenticular IC)
- VASCULATURE: PChA
- FUNCTION: Auditory input
7
Q
Lateral Geniculate Nucleus (LGN)
A
- INPUT: Optic tract (contra visual field)
- OUTPUT: V1 (primary visual cortex) in occipital love via optic radiations
- VASCULATURE: PChA
- FUNCTION: contralateral visual field
- LESION: contralateral hemianopsia
8
Q
Anterior Nucleus of Thalamus (AN)
A
- INPUT: Hippocampus via fornix and mammillothalamic tract
- Densest ACH input from midbrain
- OUTPUT: Cingulate gyrus (reciprocal) so limbic
- Important for scenery
- VASCULATURE: Tuberothalamic vessels (PCA)
- FUNCTION: Memory/recall of scenes
- LESION: Korsakoff’s, amnesia
9
Q
Mediodorsal Nucleus
A
- INPUT: amygdala, olfactory cortex, ventral pallidum
- OUTPUT: vmPFC, limbic system
- VASCULATURE: Paramedian vessels of PCA
- FUNCTION: Attention, planning, active mem
- LESION: Apathy, memory changes, perseveration
- Most highly developed thalamic nucleus in humans
10
Q
Pulvinar
A
- INPUT: Retina, superior colliculus, STT, association cortices
- Vision-heavy
- OUTPUT: Association cortices, esp. parietal
- VASCULATURE: PChA
- FUNCTION: Integration of sensory stim including “where” pathway
- LESION: Visual perception, pain perception, language processing
- Note: acts in concert with pulvinar
11
Q
Laterodosal Nucleus (LD)
A
- INPUT: hippocampal region via fornix
- OUTPUT: parietal, retrosplenial cortex (reciprocal)
- FUNCTION: spatieal learning and memory
- LESION: Korsakoff’s
Note: acts in concert with anterior nuclei
12
Q
Midline Nuclear Group
A
- INPUT:
- Midbrain PAG
- ACH from ascending arousal system
- Locus coeruleus: NE
- Midbrain raphe nuclei: 5HT
- OUTPUT: cortex, striatum
- Also reciprocally connected to SCN
- VASCULAR: Basilar paramedians
- FUNCTION: general cortical arousal
- LESION: amnesia
13
Q
Intralaminar Group
A
- INPUT:
- Motor cortex
- ACH from ascending aroual system
- OUTPUT: MSNs of striatum of BG
- FUNCTION: attention to motor tasks
- VASCULATURE: tuberothalamic artery
- LESION: of centromedian nucleus = unilateral motor neglect
14
Q
Thalamic Reticular Nuclei
A
- changes the relay neuron burst signal to tonic signal for synchronou activity between thalamus and cortex
- Signaled by cholinergic fibers from midbrain and pons (mesopontine cholinergic neurons)
- Exhibit a single-spike inhibitory (GABA) tonic firing frequency when activated, which changes the relay neuron burst signal to tonic signal.
- Do not perform this change to tonic signal during sleep
15
Q
Artery of Percheron (AOP)
A
- Single branch off of one PCA ends up supplying bilateral paramedian territories (mediodorsal thalamus)
- Vulnerable to bilateral infarction
- MD targets the reward system, vmPFC so they have profound apathy
