Midterm 3 Flashcards
What is sensory modulation of locomotion important for?
- initating walking
- controlling phase transitions
- regulating level of muscle activity
what occurs with stimulation of afferent type 1 (group 1) in decerebrates?
flexion is inhibited! The stimulation interrupts the flexor AP firing rate
In the experiment with the decerebrated cat, what happened when they dropped one of the stepping plates by 4cm?
The cat’s extensors had a big reaction (i think), and we see an EMG burst. The cat can react accordingly to the dropped plate despite having their nerves cut.
What is tonic descending input?
Tonic: always on
- constant descending input can modulate muscle activity
- these inputs can be IPSP or EPSP, and descending neurons will make synaptic connections with neurons in the reflex arc
- we can modulate how much of IPSP or EPSP is dropped, so that we can get enough input for a reaction
- Allows a previous reflex input that didn’t have enough bang, to get to the threshold
where does input descend onto to balance EPSP and IPSP?
1a inhibitory interneuron
what needs to be done before we initiate a movement?
reciprocal/1b inhibition needs to be removed. (we have to set the table before moving)
What is the theory behind the recovery of walking in patients who have lost the ability?
the theory is that we can kick start the CPG by repetitive practice. If we provide appropriate sensory feedback through specific movements, people can regain the ability to walk
In decerbrate subjects, how can we explain the avoidance of obstacles?
with walking, we visually plan the next step to prevent stumbling. We talk input from a lot of higher centres, like motor cortex, visual input and brainstem. When people are decerebrated, we lose this input. HOWEVER, we also get feedback from moving limbs that contribute to the CPG. this is why we can still avoid obstacles even after losing all descending input from higher centres.
______ allows for better control of reflexes
tonic input
what can happen when someone has a really bad stroke?
they can lose inhibition of the 1a afferent, which results in uncontrolled reflexes (you forget how to set the table for a movement).
What do tonic signals do from the brainstem?
Initiate signals (constantly)
What does supraspinal control from motor cortex and brain stem do for movement?
- balance
- task selection
- navigation
- obstacle avoidance
What is the organization from top to bottom of inputs for CPG?
- visual cortex
- motor cortex and cerebellum
- basal ganglia and brainstem
- feedback from limbs
- spinal cord with CPG
- muscles
What happened with Baby Hugo when he was hooked up to a treadmill?
He can walk backwards, and when he gets turned around, he starts adducting and then he starts to braid. its a super complex movement and he cant even walk yet, but it is because afferent information is driving his CPG
What is the vestibular sense?
It is a system within your ear that is important for proprioception?
how many peripheral apparati are there? where are they located?
2, one per ear
why is it important for the vestibular sense to have two ear inputs?
because it allows for the system to work well. A stimulus on one side results in an opposite reaction on the other side. Allows perception of position to be much more accurate.
what happens if we lose vestibular sense, or it starts malfunctioning?
we get nauseous or dizzy
what are the major roles of the vestibular system?
- Roll
- Pitch - anterior posterior
- Yaw - rotational around the z axis
where is the vestibular system?
inner ear
Is the vestibular system separate from the ear/cochlea?
No, it is continuous with the ear system, like a balloon animal, the three hoops and big swelling all flow into the cochlea.
what nerve is important for the vestibular system
8th cranial nerve
what nerve innervates the semicircular canal
8th cranial nerve, vestibular branch
what nerve innervates the cochlea?
8th cranial nerve, cochlear branch
