Central Processing of somatosensory input

Question 1

What is carried in the dorsal column medial lemniscal pathway?

Answer 1

Discriminatory touch, pressure, vibration, conscious proprioception

Question 2

What is carried in the spinothalamic tract?

Answer 2

Pain, thermosensationm crude touch, itch, tickle

Question 3

Where is the decussation of the DCML pathway?

Answer 3

Brainstem

Question 4

Where is the decussation of the spinothalamic tract?

Answer 4

At all levels of the cord- close to the point of entry via lissauer’s tract

Question 5

Dorsal columns consist of the _____ _____ ____ and the more lateral _____ _____

Answer 5

Dorsal columns consist of the medial gracile tract and the more lateral cuneate tract

Question 6

Sensory input to T6 and below (including legs and lower trunk) travels in the ______ ____ whereas input above level T6 travels in the _____ ____

Answer 6

Sensory input to T6 and below (including legs and lower trunk) travels in the gracile tract whereas input above level T6 travels in the cuneate tract

Question 7

Across the columns there is a somatosensory map of sensory inputs from lateral to medial: _______, ______, ______ and ______

Answer 7

Across the columns there is a somatosensory map of sensory inputs from lateral to medial: cervical, thoracic, lumbar and sacral

Question 8

Dorsal and ventral spinocerebellar tracts convey unconscious _______ information to the ______: important in motor coordination

Answer 8

Dorsal and ventral spinocerebellar tracts convey unconscious proprioceptive information to the cerebellum: important in motor coordination

Question 9

1st order neurones of the DCML synapse

Answer 9

Deep in the dorsal horn upon 2nd order neurones (spinal reflexes)
OR
in the dorsal column gracile nucleus or cuneate nucleus

Question 10

Axons of 2nd order neurones of the dorsal column nuclei cross collectively in the _____ _______ ________ and ascend in the _______ _______ to the ______ ________ _____ nucleus of the ______

Answer 10

Axons of 2nd order neurones of the dorsal column nuclei cross collectively in the great sensory decussation and ascend in the medial lemniscus to the ventral posterior lateral nucleus of the thalamus

Question 11

3rd order thalamic neurones of the DCML pathway project to the _______ _____________ cortex via the ________ ________ _______

Answer 11

3rd order thalamic neurones of the DCML pathway project to the primary somatosensory cortex via the posterior internal capsule

Question 12

What is stereognosis?

Answer 12

Ability to recognise an object by feeling it

Question 13

What are the capabilities of the DCML pathway?

Answer 13

Stereognosis
Vibration Detection
Fine touch
Conscious proprioception
Weight discrimination

Question 14

What produces contrast enhancement?

Answer 14

When information is conveyed from one neurone to the next in a sensory pathway, differences in the activity of adjacent neurones are amplified, producing contrast enhancement

Question 15

What is lateral inhibition?

Answer 15

When one neurone is active it inhibits the activity of its neighbours via inhibitory interneurons, a process known as lateral inhibition

Question 16

What is the role of lateral inhibition?

Answer 16

It sharpens stimulus perception and is one mechanism by which information is transformed at the synapses of the DCML pathway

Question 17

What mediates general somatic information from the anterior head?

Answer 17

Two trigeminothalamic pathways

Question 18

What are the two trigeminothalamic pathways

Answer 18

1) Central terminals of the trigeminal nerve synapse upon second order neurones in the chief sensory nucleus (general tactile stimuli) and then decussate and project to the ventroposteriomedial nucleus of the thalamus
2) Central terminals of the trigeminal nerve synapse upon second order neurones in the spinal nucleus (pain, temperature information) and then decussate and project to the ventroposteriomedial nucleus of the thalamus

Third order neurones then relay information to the cortex via thalamocortical neurones

Question 19

Where is the somatosensory cortex located?

Answer 19

Post central gyrus of the parietal cortex- posterior to the central sulcus and adjacent to the posterior parietal cortex

Question 20

The ____ are the top of the post central gyrus with the _____ at the lower end, but the _______ separates the head from the face

Answer 20

The toes are the top of the post central gyrus with the tongue at the lower end, but the hand separates the head from the face

Question 21

How many layers are present in the somatosensory cortex?

Answer 21

six cell layers (I-VI) superficial to deep

Question 22

What happens to the somatotopic map if a finger is amputated?

Answer 22

The area in the brain representing that part will respond to stimulation of the adjacent areas

Question 23

The posterior parietal cortex receives and integrates information from where?

Answer 23

SI
Visual
Auditory
Subcortical areas- thalamus

Question 24

What does the posterior parietal cortex (through stroke) can cause bizarre neurological disorders such as ……with sensory skills intact

Answer 24

agnosia
asteriognosia
hemispatial neglect syndrome