Anatomy-Dorsal Thalamus

Question 1

What structures belong to the diencephalon?

Answer 1

Dorsal thalamus, epithalamus (stria medullaris thalami, habenula, posterior commissure, pineal), hypothalamus, subthalamus

Question 2

The internal medullary lamina divides the thalamus up into what four main groups?

Answer 2

Lateral group: composed of a ventral group (ventral anterior, ventral lateral & ventral posterior) and a dorsal tier (lateral dorsal and lateral posterior). Anterior group. Medial group. Posterior group: composed of pulvinar, medial geniculate nucleus and lateral geniculate nucleus.

Question 3

What inputs are received by the thalamus?

Answer 3

All ascending sensory information (except olfaction), motor systems (basal ganglia & cerebellum), ARAS and limbic system.

Question 4

What are the functional categories of the thalamus?

Answer 4

Specific relay (well defined input and output to cerebral cortex), diffuse (widespread cortical output) and subcortical (projects to other thalamic nuclei). Note that all projections to the cortex are reciprocal.

Question 5

What thalamic nuclei receive motor information and send it on to the motor cortex?

Answer 5

Ventral anterior nucleus, Ventral lateral nucleus (the ventral lateral anterior and posterior parts) and the dorsal medial nucleus.

Question 6

What are the inputs and outputs of the VA thalamic nucleus?

Answer 6

Input: basal ganglia. Output: supplementary motor area (involved in motor planning)

Question 7

What are the inputs and outputs of the VLa and VLp thalamic nuclei?

Answer 7

Basal ganglia -> VLa -> Supplementary motor area. Cerebellum -> VLp -> Lateral premotor cortex & Primary motor cortex.

Question 8

What are the inputs and outputs of the DM thalamic nuclei?

Answer 8

1) Substantia nigra -> DM -> Frontal eye fields (gaze control). 2) Amygdala & Olfactory Cortex -> DM -> Prefrontal cortex (emotion, pain, memory) 3) Olfactory bulb -> Olfactory Cortex -> DM -> Olfactory cortex

Question 9

Which thalamic nuclei are involved in relaing limbic activity?

Answer 9

Dorsal medial, anterior and lateral dorsal.

Question 10

What are the inputs and outputs of the anterior thalamic nucleus?

Answer 10

1) Mammilary body and Hippocampal formation (via fornix) -> Anterior nucleus -> Anterior Cingulate gyrus

Question 11

What are the inputs and outputs of the lateral dorsal thalamic nucleus?

Answer 11

Limbic regions -> Lateral Dorsal nucleus -> Posterior cingulate cortex

Question 12

What thalamic nuclei are thought to be the link between our autonomic functions and our actual behaviors?

Answer 12

Anterior and lateral dorsal thalamic nuclei. They relay information related to the limbic system.

Question 13

A patient presents to the clinic complaining of difficulty filling gaps in memory and acquiring new information. History reveals alcoholism. What could be causing his condition?

Answer 13

He has B1 thiamine deficiency causing Korsakoff’s syndrome. This is characterized by degeneration of the dorsal medial thalamic nucleus.

Question 14

What thalamic nuclei receive sensory information and relay it to the cortex?

Answer 14

Ventral Posterior Lateral (ML, STT) Ventral Posterior Medial (face sensation), Ventral Posterior Medial ParvoCellular (taste), Medial geniculate body

Question 15

Inputs and outputs of VPL thalamic nucleus?

Answer 15

Medial lemniscus & spinothalamic tract -> VPL -> Primary somatosensory cortex

Question 16

Inputs and outputs of VPM thalamic nucleus?

Answer 16

Trigeminothalamic tract -> VMP -> Primary somatosensory cortex

Question 17

Inputs and outputs of VPMpc thalamic nucleus?

Answer 17

Solitary nucleus -> CTT -> VMPpc -> just anterior to face sensory homunculus

Question 18

Inputs and outputs of the medial geniculate body?

Answer 18

Inferior colliculus brachium -> MGB -> Primary auditory cortex and Secondary auditory cortex in a tonotopic representation (low frequencies rostral, high frequencies caudal)

Question 19

Inputs and outputs of the lateral geniculate body?

Answer 19

Retinal ganglion cells -> LGB’s 6 layers (crossed inputs: 1,4,6 uncrossed inputs: 2,3,5) -> Primary visual cortex

Question 20

Inputs and outputs of the pulvinar nucleus?

Answer 20

Superior colliculus -> Pulvinar -> Widespread areas of cortex & Visual association cortex (V2 & V3)

Question 21

Main function of pulvinar information?

Answer 21

Visual tracking and attention.

Question 22

Inputs and outputs of the lateral posterior thalamic nucleus?

Answer 22

Same as pulvinar

Question 23

Inputs and outputs of the intralaminar nuclei?

Answer 23

Reticular formation (via CTT) and STT -> Intralaminar nuclei -> Diffusely through cerebral cortex

Question 24

Role of the intralaminar nuclei

Answer 24

Control of EEG and the emotional aspects of pain.

Question 25

Inputs and outputs of the ventral anterior thalamic nucleus?

Answer 25

Intralaminal nuclei -> VA -> Diffuse regions of the frontal cortex

Question 26

Role of the ventral anterior thalamic nucleus?

Answer 26

ARAS control of consciousness

Question 27

Role of the reticular thalamic nucleus?

Answer 27

It is inhibitory and regulates the output of the thalamus by interconnecting with the different thalamic nuclei.

Question 28

Thalamic blood supply

Answer 28

Posterior cerebral and posterior communicating arteries.

Question 29

A patient presents to the clinic with upper extremity and facial pain that does not respond to pharmacologic therapies. History reveals a minor stroke 3 weeks ago. What is your diagnosis?

Answer 29

Thalamic pain syndrome (central pain syndrome). The stroke causes infarction of thalamic nuclei.

Question 30

Stroke w/thalamic motor symptoms? Contralateral anesthesia? Hemianopsia?

Answer 30

Motor = VA/VL. Sensory = VPL/VPM. Visual = LGB.