Somatosensory Cortex N23

Question 1

3 cortices for somatosensory processing

Answer 1

Primary Cortex (SI), Secondary Cortex (SII), and Somatosensory Association Cortex

Question 2

Cortical areas for conscious appreciation carry info from what tracts

Answer 2

DC-ML, STT, and Trigeminal

Question 3

Cortical columns

Answer 3

Columns of cells that extend from the cortical surface to the underlying white matter (6 layers)

Question 4

Sensory cortex is granular therefore ________layer(s) are enlarged

Answer 4

Layers 3 and 4

Question 5

Thalamic radiations end in

Answer 5

Layers 3 and 4 and course superficially to layer 1

Question 6

Fundamentally similar neurons would be located where in context to a cortical column

Answer 6

Above an Below (neurons on either side are different)

Question 7

Each column is stimulus specific

Answer 7

responds best to 1 type of stimulus

Question 8

Location of Primary Somatosensory Cortex

Answer 8

Postcentral gyrus, parietal lobe, 3,1,2

Question 9

4 subdivisions of Primary Somatosensory Cortex

Answer 9

3a, 3b, 1, 2

Question 10

Thalamic radiations VPM and VPL terminate in

Answer 10

3a and 3b

Question 11

3a and 3b project to

Answer 11

1, 2

Question 12

S1 has reciprocal connections with

Answer 12

SII and MI

Question 13

Sensory homunculus

Answer 13

represents the contralateral body surface (UNILATERAL)

Question 14

Size of homunculus

Answer 14

is relative to the density of innervation (lips, fingers = large)

Question 15

Somatotopy of cortex

Answer 15

lower limbs are more medial, while upper limbs and head are more lateral

Question 16

Which divisions of the primary somatosensory cortex are more complete

Answer 16

3b, 1

Question 17

Which divisions of the primary somatosensory cortex are more coarse or crude

Answer 17

3a, 2

Question 18

Function of 3a

Answer 18

input from muscle spindles

Question 19

Function of 3b

Answer 19

touch mechanoreceptors (w small fields)

Question 20

Function of 1

Answer 20

rapid-adapting cutaneous mechanoreceptors (w large fields)

Question 21

Function of 2

Answer 21

Complex: columns of slow and rapid-adapting cutaneous mechanoreceptors and underlying muscle cutaneous receptors and proprioceptors

Question 22

SI functions in initial

Answer 22

position sense, discrimination of size, shape, and texture

Question 23

3a and 2 are more crude

Answer 23

they receive info from deeper structures to determine limb position sense, shape discrimination of grasped objects
2: size and shape

Question 24

3b and 1 are more complete

Answer 24

they receive input from skin mechanoreceptors for touch perception; 1: texture

Question 25

1 and 2 are more complex

Answer 25

they receive info from 3a and 3b for processing

Question 26

Location of Secondary somatosensory cortex

Answer 26

Parietal opercular cortex, in lateral fissure

Question 27

Function of Secondary somatosensory cortex

Answer 27

BILATERAL somatotopic map; for shape and texture of stimuli; relay for association cortex; object recognition

Question 28

SII receives input mostly from

Answer 28

SI (sparse direct connections from thalamus)

Question 29

SII is used to learn new

Answer 29

tactile sensation based on object’s shape and size

Question 30

in order for SII to function properly

Answer 30

SI and SII must be intact

Question 31

Location of Somatosenory Association Cortex

Answer 31

Broman’s 5,7, superior posterior parietal lobule

Question 32

Function of Somatosensory Association Cortex

Answer 32

processes incoming sensory information and couples it with motivation, emotion, other cues; spatial orientation, mental image, stereognosis

Question 33

Input to Somatosensory Association Cortex comes from

Answer 33

SI, SII, premotor cortex, limbic system, vestibular, auditory, visual

Question 34

Somatosensory Association Cortex creates a mental image of the body meaning:

Answer 34

internal map of body to which all sensations are referred, also allows sterognosia

Question 35

Stereognosis

Answer 35

perception of 3-D shape by touch alone

Question 36

Hemineglect

Answer 36

lesions to the Somatosensory Association Cortex result in disturbances to patient’s perception in relation to the world

Question 37

Detection of movement

Answer 37

processed by Somatosensory Association Cortex

Question 38

Feature recognition neurons are found in

Answer 38

Area 1 and area 2 which are derived from elementary senses from areas 3a and 3b

Question 39

Pain perception is perceived by

Answer 39

many different areas, not just somatosensory cortices, but also limbic system (prefrontal cortex) and other

Question 40

Phantom Limb

Answer 40

damage or scar tissue may cause firing of C-fibers and tingling and burning sensation

Question 41

Rearrangement theory of phantom limb syndrome

Answer 41

remapping into adjacent cortical areas create referred sensations

Question 42

Referred sensations

Answer 42

not random; come from explicit reference fields (bc of adjacent homunculus)

Question 43

Loss of hand

Answer 43

adjacent homunculus is face and arm; face receptors connect with cortical neurons normally to hand (adapt over time)