MODULE 3: STUDY GUIDE Flashcards
What is the function gamma motor neurons?
Keeps spindles taut during muscle contraction so activity in spindle afferents is maintained.
Gamma motor neurons innervate intrafusal muscle fibers in the muscle spindle. Their role is to keep these muscle fibers taut or contracted so signals can continue to be sent via the A-alpha pathway to motor neurons to maintain contraction of the muscle. Therefore, it increases or maintains activity in A-alpha afferents. Other pathways elicit a flexor reflex.
What kind of neurons would you expect to find in the ventral and lateral portion of the anterior horn of the spinal grey matter?
Motor neurons that innervate extensor muscles in your hand.
In the ventral horn of the spinal cord, motor neurons that innervate distal muscles are located lateral and those that innervate more proximal (shoulder) or trunk muscles are located medially.
Motor neurons that innervate flexor muscles are located dorsally and those to extensors ventrally.
Motor neurons that innervate cardiac muscle are part of the autonomic nervous system and are located half way between the dorsal and ventral horn.
In your primary somatosensory cortex, it would be predicted that the cortical area devoted to representing your hand would be __________ than the region devoted to representing your back.
Larger
The hand has a larger area of the sensory cortex dedicated to it than the back.
A single cortical neuron receiving input from the hand would be expected to be activated by stimulating a __________region of skin than a neuron with input from the back.
Smaller
Receptive fields on the hand are much smaller than those on the back. Therefore, stimulation would have to be confined to the small area of the skin that ultimately reaches neurons in the cortex.
Which area of the primary somatosensory cortex (SI) receives the heaviest input from the ventroposterolateral nucleus of the thalamus (VPL)?
Area 3
Areas 1 and 2 receive a relatively small input from VPL.
Area 5 is the Association Area that receives input primarily from S1.
TRUE or FALSE?
The “touching” sensation caused by contacting your fingertip with a soft Q-tip would likely be perceived more quickly in the sensory cortex than the “burning sensation” caused by contacting your finger with a very hot soldering iron.
True
TOUCH SENSATION IS CONVEYED BY RAPIDLY CONDUCTING A-BETA FIBERS.
THE BURNING SENSATION IS CONVEYED BY MORE SLOWLY CONDUCTING C-FIBERS (AND PROBABLY ALSO A-DELTA).
The basic circuit in the visual system is:
Photon of light ---> photoreceptor ---> bipolar cell---> ganglion cell ---> lateral geniculate nucleus ---> visual cortex
In the visual system:
A bright light would result in hyperpolarization of an off-center bipolar cell.
Cones are very light sensitive and in dim light they are not as active. Rods are mainly active in dim light.
On-center bipolar cells are activated when a light turns on (hence the name on-center).
The axons of ganglion cells for the optic nerve.
Normally release of glutamate from photoreceptors depolarizes off-center bipolar cells. When the light comes on, glutamate release is decreased and thus there is a decreased depolarization of off-center bipolar cells thus their membrane potential becomes more hyperpolarized.
An ocular dominance column:
Is defined as alternating stripes of neurons in the visual cortex that respond preferentially to input from one eye or the other.
A Blob
Contains clusters of neurons interspersed between orientation columns that are mostly concerned with color.
A receptive field
Is the particular region from which a light stimulus will trigger the firing of a photoreceptor
Which of the following is an upper motor neuron?
Pyramidal cell in primary motor cortex (M1)
lower motor neurons include
Alpha Motor Neurons
Gamma Motor Neurons
Facial Motor Neurons
Which of the following areas is involved in responding to internally guided inputs?
Supplementary motor cortex
Primary motor cortex
involved in voluntary control of movement.
