Midterm 2 - Unit 3 Lecture 3 Flashcards
The nervous system can use visual and kinesthetic input to
control movement
control parameters of motor commands
to trigger commands
to correct errors in trajectory
From visual cortex, information goes to
Two visual systems (pathways):
Dorsal Stream (where)
Ventral stream (what)
Dorsal Stream (where) function
involved in spatial awareness and guidance of actions (e.g., reaching).
Where does the dorsal stream project to
posterior parietal cortex
Ventral stream (what) function
recognition and discrimination of visual shapes and objects
Where does the Ventral stream project to
temporal cortex
what is Proprioception
Sense of limb movement
First-order sensory neurons transmit information from…
peripheral receptors to the medulla
what is the dorsal column medial lemniscal pathway
is a sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception (position) from the skin and joints
how does the dorsal column medial lemniscal pathway receives information
from sensory receptors throughout the body,
what are the three groupings of neurons that are involved in the dorsal Column-Medial Lemniscus pathway:
first-order neurons
second-order neurons
third-order neurons
what are first-order neurons
are sensory neurons located in the dorsal root ganglia, that send their afferent fibers through the two dorsal columns – the gracile tract, and the cuneate tract
where do the first-order neurons make contact with the second-order neurons
in the lower medulla
second order neuron send signal from
medulla to contralateral Thalamus
third-order neurons carry signal from
thalamus to somatosensory cortex
where does the signal go from the third-order neurons
Thalamus to Somatosensory cortex
what is the anterolateral pathway
an ascending pathway that conveys pain, temperature (protopathic sensation), and crude touch from the periphery to the brain.
what are the three main pathways that the anterolateral pathway is comprised of
Spinothalamic(thalamus)
Spinoreticular(pons)
Spinomesencephalic (midbrain)
How do neurons travel in the Spinothalamic(thalamus) tract
starts with the dorsal root ganglions (These dorsal root ganglia lie adjacent to the spinal cord and represent the first-order neuron of the spinothalamic tract pathway)
Cross midline (over 2-3 segments)
(Ascend in anterolateral white matter)
Thalamus
Somatosensory cortex
function of Somatosensory Cortex
processing afferent somatosensory input and contributes to the integration of sensory and motor signals necessary for skilled movement.
Information from the somatosensory cortex relays to…
secondary somatosensory cortex and parietal cortex for integration
function of pareital cortex
integrate information on proprioception, touch, space navigation, and language processing.
Visual, kinesthetic or both? in regards to movement
Find that when both are available, a weighted combination of sensory information is used
Vision and proprioception are used to guide reaching movements
Likely use whichever is better for the task
Proprioception for finely controlled movements like handwriting, piano playing
Vision for movements to targets in extrapersonal space
Vestibular System Function
Involved in the control of balance
Positioning of head and neck
Controls eye muscles/reflexes
how are Vestibular signals carried
via vestibulo-cochlear nerve (CN VIII) to ipsilateral vestibular nuclei
how does visual info travel
eyes
visual cortex or brain stem
From the visual cortex, visual information divides further into the dorsal stream (for action) and the ventral stream (for recognition)
how does Proprioceptive information travel
spinal cord (for reflexive movements)
higher brain centres (sensory cortex, then integrated in parietal cortex)
