Flashcards in Lecture 10: Continued Deck (27)
What does afterdischarge prevent the muscle from doing?
Relaxing for some time after fatigue.
What is afterdischarge the result of?
Afterdischarge is the result of persistent neural activity in polysynaptic circuits.
What develops a "motor image' of the total muscle movement that is to be performed?
anterior part of the premotor cortex
What does the supplementary motor cortex program?
Complex motor sequences and is responsible for mental rehearsal for a movement.
What do premotor and supplementary motor cortices generate?
A plan for movement.
*transfer plan to primary motor cortex*
What do signals generated in the premotor and supplementary motor cortices cause?
Signals generated here cause more complex patterns of movement than the more discrete pattern generated by the primary motor cortex.
What does the image in the posterior motor cortex excite?
Each successive pattern of muscle activity required to achieve the image.
Where does the posterior motor cortex send signals to?
--> primary motor cortex
--> Basal nuclei and thalamus -> primary motor cortex
What are mirror neurons?
> become active when a person preforms a specific motor task or when he/she observes the same task performed by others.
> these neurons transform sensory representations of acts that are heard or seen into motor representations of these acts.
How does damage to Broca's area affect speech?
Does not prevent a person from vocalizing but makes it impossible for the person to speak whole words rather than uncoordinated utterances or an occasional simple word such as "no" or "yes".
How is Broca's area related to associated respiratory and voluntary eye movement fields?
> A closely associated cortical area also causes appropriate respiratory function, so respiratory activation of the vocal cords can occur simultaneously with the movements of the mouth and tongue during speech.
> In the premotor area immediately above Broca's area is a locus for controlling voluntary eye movements. Damage to this area prevents a person from voluntarily moving the eyes toward different objects.
- instead, the eyes tend to lock involuntarily onto specific objects, an effect controlled by signals from the occipital visual cortex. The frontal area also controls eyelid movements such as blinking.
How many layers do each vertical column of the motor cortex contain?
6 distinct layers
In the vertical columns of the motor cortex, in which layer are pyramidal cells found?
Which layers of the vertical columns of the motor cortex do input signals enter?
What does each vertical column of the motor cortex stimulate?
Each column stimulates a group of synergistic muscles or even a single muscle.
What do neurons arising in the 6th layer of the vertical columns of the motor cortex communicate with?
Other regions of the cerebral cortex.
What are cells in the motor cortex organized into?
True or False:
A typical descending pathway consists of a series of two motor neurons.
What are the two motor neurons that make up a typical descending motor pathway?
> upper motor neurons (UMNs)
> lower motor neurons (LMNs)
Are upper motor neurons (UMNs) located entirely within the CNS?
Where do upper motor neurons (UMNs) originate in?
> cerebral cortex
What do upper motor neurons (UMNs) in the descending motor pathway form?
Where do lower motor neurons (LMNs) of the descending motor pathway begin?
> from anterior horns of spinal cord
> from brainstem cranial nerve nuclei
What type of neuron makes up the lower motor neurons (LMNs)?
A-alpha motor neuron
True or False:
Lower motor neurons make up spinal and cranial nerves.
Notice that on the motor homunculus, vocalization takes up the greatest area for a specific motor function.
Also, the hand motor control takes up a large portion as well.