Somatosensory Cortex - 15

Question 0

Where is S-II?

Answer 0

Most lateral part of the post central gyrus buried in the lateral fissure.

Question 1

Where is S-I?

Answer 1

Post central gurus

Question 2

What is the general function of the somatosensory cortex?

Answer 2

Perception and comprehension of somatosensory modalities including touch proprioception and development of the sense of self and visual spatial processing.

Question 3

Why is somatosensory function important?

Answer 3

The somatosensory information is required for motor planning.

Question 4

What happens to somatosensory information after it is processed?

Answer 4

The stimuli are sent to the frontal lobe to take action and make an appropriate motor plan.

Question 5

Flow of sensory processing

Answer 5

Anterior ➡️ posterior =

perception ➡️ comprehension

Question 6

Primary Somatosensory cortex. What does it do?

Answer 6

Simple perception area. Inputs from the VPL and VPM of the thalamus from the medial lamniscus. Basic perception, crude features of shape size texture and weight; low definition.

Question 7

Secondary somatosensory cortex. What does it do?

Answer 7

Complex perception of higher order cortex. Beginning stages of comprehension. More complex perception, find resolution, high definition identification, details of texture, shape, direction, and speed if it is moving.

Question 8

Posterior parietal cortex. What does it do? What symptoms would a lesion here cause?

Answer 8

Unimodal Comprehension. Interpretation/comprehension of stimulus info from S1 and S2 only. Gives meaning to stimulus from these areas. Development of a sense of spatial awareness and relationship “sense of self”. Organization of self in relation to surrounding external environment.
⭐️lesions here lead to neglect

Question 9

Parietal-temporal-occipital area. What does it do?

Answer 9

Heteromodal association cortex. The highest order association area. Interpretation and comprehension from all modalities: somatosensory + auditory + visual. Integration of all stimuli into a meaningful identification.

Question 10

Language comprehension requirements

Answer 10

Requires processing visual (written word) and auditory (spoken word) stimuli

Question 11

Which Brodman’s areas make up SSI?

Answer 11

3a, 3b, 1, 2

Question 12

Where do most of the 3rd order axons of DCML project to from the thalamus?

Answer 12

3a, 3b ➡️ from contralateral body

Question 13

3a & 3b neurons do what, and send info where?

Answer 13

Simplest neurons, exclusively involved in perception of stimuli. Processed information sent to 1 and 2

Question 14

Which two areas receive information from skin receptors?

Answer 14

3b and 1

Question 15

Which areas receive info from proprioceptors?

Answer 15

3a and 2

Question 16

What type of info can area 1 perceive?

Answer 16

Area 1 has first feature detecting neurons. Beginning of adding details and dimension to stimuli. Start detecting direction and orientation.

Question 17

What type of info can area 2 perceive?

Answer 17

More extensive feature detecting neurons are found here. There is more complex processing for finer localization of moving stimulus (texture, weight, size) this is the transition zone between perception and comprehension with initial comprehension starting here.

Question 18

What types of symptoms will be produced with a lesion to SS1?

Answer 18

Symptoms would be just like a lesion to the DCML which would be a loss of fine touch, vibration, and proprioception. As well as signs of agnosia, “sensory blindness”, Agraphesthesia, Asterognosia, and hemihypesthesia.

Question 19

What symptoms would be caused by a lesion to area two and beyond?

Answer 19

This would be a lesion in the comprehension areas so it leads to a lack of meaning of a stimulus. The stimulus is felt but it is not comprehended. Also known as neglect syndromes.

Question 20

Which of Broadman’s areas makes up the posterior parietal cortex?

Answer 20

5 and 7 for the superior parietal lobule. 39 and 40 for the inferior parietal lobule

Question 21

What type of information is processed in posterior parietal cortex? Where does the information come from?

Answer 21

These are pure comprehension centers. They receive their input from S1 and visual centers so they can use the visual system to identify a stimulus as well as somatosensory

Question 22

What is the primary function of the posterior parietal cortex?

Answer 22

Body and spatial awareness

Question 23

What symptoms does a lesion in the posterior parietal cortex cause?

Answer 23

A lesion here causes contralateral hemineglect and complex symptoms like dyslexia.

Question 24

What is the main function of area 5?

Answer 24

This area integrates tactile information from skin mechanoreceptors and proprioceptors in the muscles. It also integrates information from bilateral hands

Question 25

What is area 7 responsible for?

Answer 25

This area receives visual and proprioceptive input and integrates them into sterognostic and visual outputs to frontal lobe.

Question 26

What is the most important role of area 7?

Answer 26

Hand eye coordination