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
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
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
becomes activated when pain judged to be more unsettling and unpleasant
what does the parabrachial nucleus do?