Exam 2- week 7 ppt 3 Cerebrum functional organization

Question 1

Mapping the cortex has been made into ____ histologically different areas (______ areas)

Answer 1

52 area

Brodmann areas

Question 2

Details on the mapping of Broadmann areas

Answer 2

~they are not sequentially numbered
~many Brodmann areas correspond to specific functional areas
~there are some important caveats to remember when looking at the maps of Brodmann areas

Question 3

Are the Brodmann areas exactly the same in everyone?

Answer 3

NO

~there is structural variation between brains so the Brodmann maps for different individuals would be slightly different

Question 4

Brodmann areas: Caveats

Answer 4

~Variation of distribution of areas between individual brains
~Boundaries between different cytoarchitectonic areas not as distinct as shown on maps
~Because of cerebral plasticity areas can change with time and with differing environmental influences

Question 5

Brodmann area: Caveat

Details on Boundaries btw cytoarchitectonic areas

Answer 5

~there are gradations of patterns of cell types between one Brodmann area and the next

Question 6

Brodmann area: Caveat

Details on Brain plastic

Answer 6

~for instance learning motor tasks that stress hand motions, there may be an expansion of the hand region in the cortex. Following amputation, areas of cortex serving the amputated region might disappear to be replaced by neighboring regions of the cortex.

Question 7

The functional areas of the cortex are divided into (3)

Answer 7

~primary functional areas
~unimodal association areas
~multimodal association areas

Question 8

location of the primary motor area

Answer 8

~along the precentral gyrus laterally and anterior portion of paracentral lobule medially

Question 9

Primary motor area’s neurons produce

Answer 9

~specific muscle activation somatotopically arranged

Question 10

Primary motor area’s muscle pattern of activation called

Answer 10

motor homunculus

Question 11

Primary motor area:

LE and Trunk are located

Answer 11

medially and dorsal

Question 12

Primary motor area: UE and face are located

Answer 12

laterally and ventral

Question 13

Details about innervations and body parts

Answer 13

~size of the body part in this representation is related to innervation density
~innervation density of the muscles of facial expression and of the hand are very high
~these areas have small motor units (number of muscle cells activated by each motor neuron) and large numbers of upper motor neurons
~these areas have a high precision of movement

Question 14

Location of Primary somatosensory area

Answer 14

along the postcentral gyrus and posterior portion of paracentral lobule medially

Question 15

Primary somatosensory area’s neuron specifically respond to _ distinct modalities of the somatosensory input (and name them)

Answer 15

5
~discriminative touch
~pain
~temperature
~pressure
~localized vibratory sense

Question 16

Details on primary somatosensory area (functional analysis)

Answer 16

~inputs to the post-central gyrus include the integration of superficial & deep mechanoreceptive information for appreciation of position and movement – proprioception
~tactile discrimination for the precise localization of tactile stimuli can be accomplished
~the ability to recognize an object by touch alone (without vision) – stereognosis thought the convergence of different tactile input onto the same neurons and groups of neurons

Question 17

Primary somatosensory area: differential functions

Answer 17

post central gyrus is not homogeneous in terms of it function but different areas within the post-central gyrus have different patterns of connections and patterns of response to sensory stimuli

Question 18

Primary somatosensory area: differential functions (area 3)

Answer 18

~BA 3 is considered the primary somatosensory cortex bc it receives dense thalamic inputs and has neurons that are directly and highly responsive to somatosensory stimuli
~BA 3 considered primary somatosensory cortex also because lesions impair somatic sensation very specifically
~Electrical stimulation of BA 3 evokes specific somatic sensory experiences
~BA 3 receives both direct tactile and proprioceptive input

Question 19

Primary somatosensory area: differential functions (area 1&2)

Answer 19

~BA 1 &2 receives dense inputs from area 3
~BA 1 receives texture info
~BA 2 function emphasizes determination of size and shape
~Lesions in BA 1 & 2 produce predictable dysfunction in texture sensation and size and shape discrimination
~this specificity is not clinically relevant bc you rarely have such discrete lesions of the post-central gyrus

Question 20

Primary somatosensory area: columnar arrangement

Answer 20

~Areas represented on the cortex correspond to receptor and afferent fiber density with greatest representation of face & hand
~the receptor density is very high the size of receptor fields (area covered by a single receptor unit) is very small in the face and hands
~Like other areas of cortex, somatosensory cortex is arranged in columns
~Adjacent columns represent the same body areas but are alternating between slowly adapting or rapidly adapting neuronal responses reflecting the slow and fast adapting sensory receptors found in the same area of skin

Question 21

location of the primary auditory cortex

Answer 21

along the most superior aspect of the superior temporal gyrus and into the insular portion of the temporal lobe

Question 22

primary auditory cortex: tonotopic mappic of pitch

Answer 22

~low frequencies mapping more rostrally (anterior)

~high frequencies mapping ore posteriorly

Question 23

Location of primary visual cortex

Answer 23

along the medial aspect of occipital lobe, just inferior to and within calcarine sulcus

Question 24

Details on the primary visual cortex

Answer 24

~respinsice basicaaly only to points of light
~limited patterns of light and dark (such as bars of light)
~there is a retinotopic mapping of PVC with the fovea of the retina represented posterior and the peripheral retina represented more anterior (rostral)

Question 25

location of primary vestibular area

Answer 25

not as well localized, but is associated with the insula of the parietal lobe

Question 26

what does the primary vestibular area do?

Answer 26

gives sensation of head position and movement

Question 27

Lesion in primary somatosensory

Answer 27

lead to loss of tactile localization and conscious proprioception

Question 28

Lesion in primary auditory

Answer 28

lead to loss of localization of sounds

Question 29

Lesion in primary visual

Answer 29

leads to loss of field of view called homonymous hemianopia

Question 30

Lesion in primary vestibular

Answer 30

change in the awareness of head position and movement

Question 31

Where are the unimodal sensory association cortices?

Answer 31

adjacent to their primary sensory areas

Question 32

What are the inputs for the unimodal association cortices?

Answer 32

~thalamus

~primary cortex for that sense

Question 33

What is the principal outputs for the unimodal association cortices?

Answer 33

principal outputs of each of these association cortices are to primary cortex for that sensation

Question 34

somatosensory association cortex is located

Answer 34

just posterior to the primary somatosensory cortex w largest areas superior medial and inferior lateral

Question 35

auditory association cortex is located

Answer 35

along superior temporal gyrus

Question 36

visual association cortex is located

Answer 36

is surrounding the primary visual cortex

Question 37

Agnosias

Answer 37

inabilities to recognize objects using that sense, even though the primary sense is intact

Question 38

Agnosias is the results of

Answer 38

lesions to the secondary or association sensory cortices

Question 39

Astereognosis

Answer 39

~inability to detect an object by touch alone

~damage to the somatosensory association cortex

Question 40

Visual agnosia

Answer 40

~inability to recognize visual images

~damage to visual association cortex

Question 41

auditory agnosia

Answer 41

~inability to recognize and identify sounds

~damage to the auditory association cortex

Question 42

Motor association cortices are located

Answer 42

just rostral to primary motor cortex

Question 43

what are the 3 parts of motor association cortices?

Answer 43

~premotor cortex
~supplementary motor cortex
~frontal eye fields

Question 44

location of premotor cortex

Answer 44

rostral and inferior to primary motor cortex

Question 45

location of supplementary cortex

Answer 45

rostral and superior to the primary motor cortex

Question 46

location of frontal eye field

Answer 46

rostral to both primary motor cortex and to the supplementary and premotor cortices

Question 47

Premotor cortex function

Answer 47

to associate group of muscles rather than the individual activation of muscles of the primary motor cortex

Question 48

Supplementary motor cortex function

Answer 48

in the initiation of movement

Question 49

Frontal eye field function

Answer 49

coordinates conjugate eye movement