CNS 3 Flashcards
Neural signals of a given modality from a particular region of the body travel along specific pathways to the brain (Called
“labelled” or “private” lines).
The ability to locate a stimulus depends on the
size and density of receptive fields of the receptors.
Within the CNS, lateral inhibition focuses
ascending sensory signals, enhancing spatial acuity.
Ascending sensory axons synapse on neurons in the brainstem that then cross the
midline, conveying sensory information from the right side of the body to the left side of the brain and vice versa.
Two-point Discrimination
• Sensory afferent A has a smaller receptive field than afferent B, which provides greater spatial acuity
Overlapping Receptive Fields
Overlapping stimulation between neighboring receptive fields provides general information about the location of a stimulus
Divergence:
Each sensory afferent sends branches to many neurons in the CNS
Convergence
a given neuron in the CNS receives inputs from many sensory afferents
Lateral inhibition:
– “Sharpens contrast” by focusing activation of CNS neurons
– Stimulus location is perceived more precisely (↑ “acuity”)
Two-point discrimination is best on
hands and face, worst on abdomen and proximal parts of limbs
Two-point discrimination is best on hands and face, worst on abdomen and proximal parts of limbs
WHY?
- Density of receptors is highest in skin areas with the best 2-point discrimination
- Surface area of sensory cortex is largest in regions to which receptors from skin areas with the best 2-point discrimination project
The conscious awareness of a stimulus is called a
sensation
A sensation combined with an understanding of its meaning is called
perception
Are both sensation and perception a result form processing in the cerebral cortex?
YES
Topographic Maps are within the
Sensory cortex
