Voluntary Motion Flashcards
Set of cyclic, coordinated timing signals that are generated by a cluster of interconnected neurons
Central pattern generators (CPGs)
These neurons act like pacemaker cells that when combined with local interconnected circuits generates rhythms
4 organized areas of neural structures involved in the control of movement
- Local spinal cord and brainstem circuits
- Descending control from cortex and brainstem
- Cerebellum
- Basal ganglia
Role of dorsal pathway in visual processing of objects
Primary path associating vision with movement; completes motor acts based on visual input
The dorsal pathway of visual processing originates from the _______ cortex and goes to the ______ cortex
The ventral pathway of visual processing originates from the _____cortex and goes to the _____ cortex
Primary visual; parietal/frontal
Primary visual; inferior temporal
Role of ventral pathway in visual processing of objects
Primarily involved in interpreting images (recognizing or copying shapes, forms, faces)
Cortical regions invoved in reaching for an object:
Information arises from _____; output from the visual cortex dorsal stream splits into 2 pathways.
What is the difference in function of division 1 vs. division 2?
V1
Division 1 = where the object is located in space
Division 2 = mapping the location of your arms in relation to the object
In division 1 of the dorsal stream, once information from the visual cortex (V1) is projected to _____ in the parietal cortex. From there it projects to ____, ____, and _____.
V6A; PEc, MIP, VIP
In division 1 of the dorsal stream, once information from the visual cortex (V1) is projected to V6A in the parietal cortex. From there it projects to PEc, MIP (medial intraparietal area), and VIP (ventral intraparietal area). What is the function of VIP?
VIP creates a rough map of the space around you
In division 1 of the dorsal stream, once information from the visual cortex (V1) is projected to V6A in the parietal cortex. From there it projects to PEc, MIP (medial intraparietal area), and VIP (ventral intraparietal area). Where does the VIP project to and what is the function of that area?
VIP —> F4
F4 creates a detailed map of the space around you with specific knowledge of the location of the object you are attempting to grasp
In division 2 of the dorsal stream, once information from the visual cortex (V1) is projected to V6A (similar to division 1), V6A projects to ____ and _____, then to _____
PEc; AIP; F2
In division 2 of the dorsal stream, once information from the visual cortex (V1) is projected to V6A (similar to division 1), V6A projects to PEc, AIP, then to F2. What is the function of F2?
F2 constructs the map containing information about where you are in space in relation to the environment around you
In terms of cortical regions of note for actually grasping an object, information arising from V1 travels to 3 pools of neurons in the anterior intraparietal area and PFG. What are these neuron pools and what are their functions in relation to grasping an object?
- Visual dominant neurons = seeing an object you want to grasp
- Motor dominant neurons = actually grasping what you want to grasp
- Visumotor neurons = either condition
Cortical regions of note for grasping an object consist of neurons going from AIP and PFG (parts of inferior parietal cortex) finally to ____ which contributes to the action of actually grasping the object
F5
Difference between premotor, supplementary motor, and primary motor cortex in their roles relating to motor control
Premotor = determines whether it’s ok to move, identifies goal and motion required to meet that goal
Supplementary motor = postural control, identifies specific motor sequence required, changes tactics if necessary
Primary motor cortex = codes the individual motions required to reach the goal
The ____ portion of the premotor cortex in particular applies the rules that determine whether it’s appropriate to move at that time; it identifies the motion needed and decides what motion to produce
Dorsal
Which area of the motor cortex is involved in executive control and allows you to switch actions quickly?
Supplementary motor cortex
The supplementary cortex has what 2 divisions?
Supplementary motor area (SMA) = responsible for postural control; sets the motor programs of learned sequences
Pre-supplementary motor area (Pre-SMA) = plans motor program required to make an action occur; learning a sequence of complex movements
The primary motor cortex is arranged in columns. Layer ___ receives sensory input while layer ____ becomes the output for the CST (pyramidal) pathway
There are 2 sets of neurons per column, one to ___ the motion, and one to ____ the motion
IV; V
Start; maintain
T/F: within the primary motor cortex, neighboring columns control neighboring muscles
False; neighboring columns control related MOTIONS, not neighboring muscles
The _____ division of the cerebellum projects to descending brainstem and CST pathways, influencing proper execution of coordinated movements
Spinocerebellum (medial and lateral)
The ____ division of the cerebellum projects to motor cortices and controls planning, coordinating, properly timed movement sequences
Cerebrocerebellum (aka pontocerebellum)
The ____ division of the cerebellum projects to vestibular nuclei and functtions in coordinated balance and eye movements
Vestibulocerebellum
Anatomy of spinocerebellum
Vermis and intermediate parts of the hemisphere
The spinocerebellum receives input from the spinocerebellar tract of the SC and ____ n., as well as visual and auditory systems.
It sends fibers to ____ and _____ nuclei, then the cerebral cortex. It modulates descending motor systems.
Trigeminal
Interposed; fastigial
Cerebrocerebellum anatomy
Lateral parts of the hemispheres
The cerebrocerebellum receives input from the cortex via the _____, and projects to the ____ nucleus.
Ouput is back to the thalamus then on to the pre-motor nucleus and primary motor cortex, and to the _____ nucleus
Thalamus; dentate
Red
Which division of the cerebellum is involved in sequencing rapid movements?
Cerebrocerebellum
Anatomy of vestibulocerebellum
Flocculonodular lobe
Which NTs are associated with mossy fibers, climbing fibers, and purkinje cells of the cerebellum?
Mossy fibers = glutamate
Climbing fibers = aspartate (excitatory)
Purkinje cells = GABA (inhibitory)
Compare and contrast the neural controls on arm/hand motions with those that elicit walking
Both are complex and under voluntary control
Walking is rhythmic, stereotyped, associated with CPG in the SC. Initiation derives from cortex. Sensory input modifies the basic rhythm but is not required normally.
Arm/hand motion often involves single motion to reach goal, and each motion is individually determined, originating from pre-motor, SMA, motor cortex, cerebellum, and/or basal ganglia. Sensory input is crucial to creation of the correct motion.
Role of basal ganglia in voluntary motion
Involved in planning and programming of movement — particularly for its proper initiation
[modulated by behavioral contex in which movements are performed]
In terms of basal ganglia, the ____ receives the main input from nearly all of the cerebral cortex. The output from the basal ganglia (GPi and SNpr) is ______ and projects to motor areas in the brainstem and thalamus
Striatum; inhibitory
Result of damage to basal ganglia vs. damage to SNpc (substantia nigra pars compacta)
Damage to any basal ganglia structure may cause slowness of a voluntary movement, involuntary movements, involuntary postures, or a combination of these
Damage to SNpc causes tremor at rest, slowness of movement, rigidity, and postural instability, which are the main features of PD
Components of basal ganglia
Striatum (caudate + putamen)
Globus pallidus (external + internal segments)
Substantia nigra (pars compacta + pars reticulate)
Subthalamic nucleus
The striatum receives most of the inputs to the basal ganglia. The input from the cortex consists of NT ______; it also receives input from _____ neurons of substantia nigra pars compacta.
90% of the neurons in the striatum are ______, so their output is inhibitory. The intrastriatal system is cholinergic, so it is ________
Glutamate; dopaminergic
GABAergic; stimulatory
The subthalamic nucleus receives input from the ____ lobe. Its output is excitatory to other basal ganglia with NT _______
The subthalamic nucleus is kept uner tonic inhibition by _____, but disinhibition is seen in PD
Frontal; glutamate
GPe
The substantia nigra stimulates ____ receptors which are stimulatory, and _____ receptors which are inhibitory
D1; D2
The SNPC receives inputs and relays them to the _______, the motor cortices also send inputs to this area.
The ____ and _____ send axons to the thalamus; when activated, they release GABA in the thalamus, inhibiting it, and then proceed to the cortex or brainstem
Striatum
GPi; SNPR
Damage to what type of neurons is implicated in huntington disease?
Cholinergic
The basal ganglia work by inhibition and subsequent removal of that inhibition to start a movement.
The corticostriate tract (from cortex to striatum) releases ______
The nigrostriatal tract (from SN to striatum) is tonically active and releases ______
EAA
Dopamine
Functions of direct and indirect pathways for function of basal ganglia
Direct pathway facilitates flow of info through the thalamus and increases consequential excitation of the cortex by REMOVING inhibition [excited by D1]
Indirect pathway inhibits flow of info through the thalamus and decreases activity in the cortex by MAINTAINING inhibition [inhibited by D2; excited by EAA/ACh]
In parkinson disease, the SNPC input is abolished. What are the 2 effects this has on initiation of movement?
- The direct pathway becomes difficult to activate
- The indirect pathway becomes overactive (due to loss of inhibition)
Therefore we see an inability to initiate motion
Role of alpha-gamma coactivation in production of voluntary motion
Coactivation of both sets of fibers causes the tension on the muscle spindles to be maintained as the muscle shortens; thus sensitivity to stretch is maintained
