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Flashcards in Cortex- Sensory Deck (26):

what does the cerebral cortex participate in?

memory storage and recall
execution of language
musical and math abilities
conscious processing of all sensations
integration of sensory inputs
recognition of individuals, objects and places
planning & execution of complex motor activities


what is the cerebral cortex?

a mantle of gray matter on the surface of the cerebral hemispheres


the cortex can be divided into regions based on ? what are the divisions?

differences in the number of cell layers

isocortex (neocortex)= 6 layers

allocortex= 3 layers

mesocortex (zone between iso and allo)= varies 3-6 layers


what are the 6 layers of the neocortex?

1- Molecular- intracortical fibers

2- External Granular- Short ass fibers

3- External Pyramidal- Short Ass & Commissural fibers

4- Internal Granular- corticopetal fibers, thalamocortical radiations
-receptive area

5- Internal Pyramidal- cortico fugal fibers; striatum, BS, SC
-prijection fibers going down (corticospinal, corticobulbar, pyramidal tracts; biggest in motor areas)

6- Multiform- reciprocal connections to thalamus
-corticothalamic forms here


what are the 3 types of cortex?

1- sensory- heterotypical

2- associative- homotypical

3- motor- heterotypical


what is unimodal association cortex?

puts meanings to things
relate to modality we are talking about
(vision, auditory, tactile)


what is the multimodal association cortex/

parietal and prefrontal lobes where all modalities have effect on how we perceive and move


what is the blood supply to the cerebral cortex?

anterior, middle and posterior cerebral arteries

vision is posterior cerebral A


the sensory areas for somatic sensation, audition, and vision occupy large areas of the ___ ?

parietal, temporal and occipital isocortex


the primary somatosensory area (S1) includes Brodmann's area….?

Brodmann's areas 3,1, and 2 on the post central gyrus


where does the the primary somatosensory area receive projections from?

from the posterior part of the VPL nucleus and from the VPM nucleus of the thalamus

VPL- transmits info from medial lemniscus and spinothalamic tract

VPM- transmits info from the trigeminothalamic tract


how is the somatosensory sensory area divided?

divided into 4 functional areas

3a & 3b= receive most of the fibers from the thalamus

project to areas 1&2

3b= fast and slow adapting cutaneous receptors
-concerned with texture, size & shape of objects
-projections to area 1= concerned to texture
-projections to area 2= concerned w/ size & shape

3a= proprioception (muscle spindles)

**pain only projects here for location and size NOT sensation of actual pain

furthermore, inputs of individual modalities to S1 are organized in columns


what and where is the posterior parietal cortex?

higher order associative area

seems essential for the perception and interpretation of spatial relationships, accurate body image and the learning of tasks involving coordination of the body in space

interpretation of senses- puts meaning behind what we are feeling

-Area 5- integration of tactile info from mechanoreceptors in skin with proprioceptive from underlying muscles and joints (feel something w/ eyes closed)
-Area 7- visual, tactile and proprioceptive integration. Provides the basis for aligning our body centered spatial coordinate system with the environmentally defined spatial coordinate system based on somatosensory and visual inputs which converge here


what is the second somatosensory cortex (S2)?

-extensive reciprocal connections with S1
-strongly linked via transcallosal connections- bimanual coordination, rapid transfer of acquired tactile skills (discrimination from hand to the other)

Involved with the evaluation of texture and shape discrimination

Sensory discrimination of pain

lies deep underneath lateral sulcus
more bilateral, strongly linked to other side

gets most afferents from S1


what are results of a lesion to S1?

deficits in position- can't discriminate size, texture and shape
-3b- loss of discrimination of texture of objects as well as size and shape
-1- defect in the assessment of the texture of objects
-2- alter only the ability to differentiate the size and shape of objects
-3a- conscious proprioception

it could also reduce pain, temp and crude touch but since info from the spinothalamic tract is interpreted mainly by other areas of the brain (insular cortex & cingulate gyrus) it is not as relevant as the other symptoms
* can still perceive pain but accuracy of describing and locating it would be gone


what are results of a lesion to S2?

afferents from S1 & thalamus (pain)

-result in severe impairment in the discrimination of both shape and texture
-also prevents learning new tactile discriminations based on shape


what would result of a lesion to the posterior parietal cortex?

can result in bizarre neurological disorders

1- tactile agnosia

2- neglect syndrome


what is tactile agnosia?

inability to recognize objects even though simple sensory skills seem normal

astereognosia= can't recognize common objects by feel

amorphognosia= inability to judge object form

ahylognosia= impaired ability to discriminate wt, texture, density



what is neglect syndrome?

part of the body or (world) is ignored


what is fast pain?

primary pain is acute pain.
keeps you away from harmful stimulus
caused by injury- sharp- protects

stimulus on afferents (group 3 and 4 fibers; some 2 for crude touch) goes into dorsal horn to laminas 1-3, 6-- crosses over and goes up contralateral side

2 tracts together (spinothalamic) of neospinothalamic (primary) and pale tract up to the thalamus (VPL nucleus) then to somatosensory cortex for identification of what the pain is


what is slow pain?

paleospinothalamic- more medially located

driving ARAS and ascending up

pain going to affect and arousal areas- pain is very arousing= pain avoidance

slow goes through RF; influences ARAS, PAG

reaches medial thalamus then goes to corticoarousal (ARAS) area throughout brain going to affective areas (cingulate gyrus, insula, hippocampus, prefrontal lobes)

aching pain that drives behavior

slide 19!!


what happens in lots of pain?

pain modulatory systems from PAG going to rap he nuclei (serotonin) and medullary pontine tegmental area (NE) --> releases enkephalins to go down dorsal horn and get pain modulation


what does the insula do?

emotional and regulation on homeostasis
-autonomic responses to pain based on the internal state of the body

discriminating the quality and intensity of the stimulus

affective aspects of pain (intensity)

part of a network of cortical regions mediating body homeostasis
-visceral motor center- HR with exercise

projects to hypothalamus


what does the ACC do?

"anterior cingulate gyrus"- part of limbic system

emotional states- generation or control of

error detection

becomes activated when pain judged to be more unsettling and unpleasant


what does the parabrachial nucleus do?

amygdala, hypothalamus


describe discriminative sensation of the face vs the body:

large afferents ascend dorsal column--> synapse on NC & NF--> cross to form medial lemniscus--> ascend up BS to VPL--> primary sensory cortex

CN 5-->trigeminothalamic tract-->VPM