Somatosensory Cortex - 15 Flashcards
(27 cards)
Where is S-II?
Most lateral part of the post central gyrus buried in the lateral fissure.
Where is S-I?
Post central gurus
What is the general function of the somatosensory cortex?
Perception and comprehension of somatosensory modalities including touch proprioception and development of the sense of self and visual spatial processing.
Why is somatosensory function important?
The somatosensory information is required for motor planning.
What happens to somatosensory information after it is processed?
The stimuli are sent to the frontal lobe to take action and make an appropriate motor plan.
Flow of sensory processing
Anterior ➡️ posterior =
perception ➡️ comprehension
Primary Somatosensory cortex. What does it do?
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.
Secondary somatosensory cortex. What does it do?
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.
Posterior parietal cortex. What does it do? What symptoms would a lesion here cause?
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
Parietal-temporal-occipital area. What does it do?
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.
Language comprehension requirements
Requires processing visual (written word) and auditory (spoken word) stimuli
Which Brodman’s areas make up SSI?
3a, 3b, 1, 2
Where do most of the 3rd order axons of DCML project to from the thalamus?
3a, 3b ➡️ from contralateral body
3a & 3b neurons do what, and send info where?
Simplest neurons, exclusively involved in perception of stimuli. Processed information sent to 1 and 2
Which two areas receive information from skin receptors?
3b and 1
Which areas receive info from proprioceptors?
3a and 2
What type of info can area 1 perceive?
Area 1 has first feature detecting neurons. Beginning of adding details and dimension to stimuli. Start detecting direction and orientation.
What type of info can area 2 perceive?
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.
What types of symptoms will be produced with a lesion to SS1?
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.
What symptoms would be caused by a lesion to area two and beyond?
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.
Which of Broadman’s areas makes up the posterior parietal cortex?
5 and 7 for the superior parietal lobule. 39 and 40 for the inferior parietal lobule
What type of information is processed in posterior parietal cortex? Where does the information come from?
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
What is the primary function of the posterior parietal cortex?
Body and spatial awareness
What symptoms does a lesion in the posterior parietal cortex cause?
A lesion here causes contralateral hemineglect and complex symptoms like dyslexia.
