Slide 3 Flashcards
General flow of somatosensoroy info
1) axons carrying info from cutaneous receptors gather together
2) enters: dorsal root of spinal cord
3) ventral posterior (THALAMUS)
4) Primary somatosensory cortex
5) Secondary somatosensory cortex
6) association cortical regions
Where is the postcentral gyrus located?
parietal lobe
Where is the primary somatosensory cortex located?
in the postcentral gyrus
What is the name of the map of sensory space in the postcentral gyrus?
homunculus
What is somatotopic organization
- diff strips of primary somatosensory cortex
- respond to diff types of skin stimulation
- (parallel processing)
True or false: representation in primary somatosensory system is mainly contralateral
true
2 features of secondary somatosensory cortex
- somatotopic organization
- responds to input from both sides
What are the two places that somatosensory info is projected to from the secondary somatosensory cortex?
- prefrontal association cortex
- posterior parietal cortex
What is the function of bimodal neurons of the posterior parietal cortex?
- respond to somatosensory
- and visual
- info
What happens in the primary somatosensory cortex is damaged?
- reduced ability to detect/discriminate by touch
- often effects are mild
Why are effects of damage to the primary somatosensory cortex often mild?
-parallel processing
What is the effect of damage to the secondary somatosensory cortex?
somatosensory agnosia
What are the two types of somatosensory agnosia?
- Astereognosia
- Asomatognosia
What is Astereognosia?
inability to recognize an object by touch
What is Asomatognosia?
Failure to recognize own body parts
What is usually the cause of asomatognosia?
damage to posterior parietal cortex
What is pain?
- unpleasant emotion/sensation
- evoked by harmful stimulus
2 functions of pain
- alert us to danger
- grab attention
Where is pain located in the brain?
- not a single cortical area is found necessary for pain perception
- painful stimuli activate many parts of the brain
Which part of the brain responds to an emotional reaction to pain?
anterior cingulate cortex
What is descending pain control? And what is responsible for it?
- analgesia circuits
- brain sending messages to decrease responses to pain
6 steps of descending pain control
1) Endogenous opiates (endorphins) inhibit inhibitory interneurons in PAG
2) increases activity of PAG neurons that descend to raphe
3) Raphe neurons activated
4) descend down spinal cord
5) increase activity of inhibitory interneurons in spinal cord
6) inhibitory interneurons activate and block pain signal
What is the name for the inhibition of inhibitory neurons?
dishinhibition
What are the 2 chemical senses and what is their function
- gustatory
- olfactory
- monitor chemical contents of our environment
