Cortex- Sensory Flashcards
what does the cerebral cortex participate in?
memory storage and recall comprehension execution of language musical and math abilities attention perception 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
WHERE:
- 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)?
Afferents:
- thalamus
- 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
