The globus pallidus is divided into two segments, what are they called

internal/medial and external/lateral

Two signaling processes in the basal ganglia

1. The direct pathway selectively facilitates certain motor (or cognitive) programs in the cerebral cortex that are adaptive for the present task

2. The indirect pathway simultaneously inhibits the execution of competing motor programs

Direct Pathway

M S I T

Motor Cortex Striatum Internus Thalamus

Excitatory excites Inhibitory inhibits an Inhibitory which allows Excitation

Overall effect: excitation then allows for voluntary movement

Indirect Pathway

M S E N I T

Motor Cortex --> Striatum --> Externus --> Nucleus --> Internus-->Thalamus

Excitatory excites Inhibitory inhibits an Inhibitory which allows for Excitatory to excite an Inhibitory which DOESN'T allow Excitation

Overall effect: inhibition then DOES NOT allow for voluntary movement

An important pathway in the modulation of the direct and indirect pathways is the ______ from the substantia nigra pars compacta to the striatum

dopaminergic, nigrostriatal projection

Direct pathway striatal neurons have ______ dopamine receptors, which ____ the cell in response to dopamine.

D1, depolarize

Indirect pathway striatal neurons have ___ dopamine receptors,
which ______ the cell in response to dopamine.

D2, hyperpolarize

The nigrostriatal pathway thus has the dual effect of exciting the _______ while simultaneously inhibiting the _____

direct pathway

indirect pathway

Parkinson’s disease is characterized by ______ (bradykinesia or akinesia), _____, and a _____ (especially in the hands and fingers). Patients have difficulty initiating movements, and once initiated the movements are abnormally slow. The cause of Parkinson’s disease is the loss of the ______.

1. slowness or absence of movement, rigidity, and resting tremor

2. dopaminergic neurons in the substantia nigra pars compacta

Because the nigrostriatal pathway excites the direct pathway and inhibits the indirect pathway, the loss of this input tips the balance in favor of activity in the ____. Thus, the GPint neurons are abnormally active, keeping the thalamic
neurons ____. Without the thalamic input, the motor cortex neurons are not as _____, and therefore the motor system is less able to execute the motor plans in response to the patient’s volition.

1. indirect pathway

2. inhibited

3. excited

The symptoms of Huntington’s disease are in many respects the ____ of the symptoms of Parkinson’s disease. Its characterized by choreiform movements: ______, _____ movement of the body, especially of the extremities and face. Huntington’s disease results from the selective loss of _____ neurons in the _____ pathway.

1. opposite

2. involuntary, continuous

3. striatal

4. indirect

The balance between the direct and indirect pathways becomes tipped in favor of the _______. Without the normal inhibitory influence on the thalamus that is provided by the indirect pathway, thalamic neurons can _____ and _____ causing the motor cortex to execute motor programs with no control by the patient.

1. direct pathway

2. fire randomly and inappropriately

The _________ separates the flocculonodular lobe from the corpus cerebelli

posterolateral fissure

The ___________ separates the corpus cerebelli into a posterior lobe and an anterior lobe

primary fissure

Vestibulocerebellum. The vestibulocerebellum comprises the _____ and its connections with the ___________ nuclei. Phylogenetically, the vestibulocerebellum is the oldest part of the cerebellum. As its name implies, it is involved in vestibular reflexes (example?) and in postural maintenance.

1. flocculonodular lobe, lateral vestibular
2. vestibuloocular reflex

Spinocerebellum. The spinocerebellum comprises the ______and the______ of the cerebellar cortex, as well as the fastigial and interposed nuclei. As its name implies, it receives major inputs from the ________. Its output projects to rubrospinal, vestibulospinal, and reticulospinal tracts. It is involved in the integration of sensory input with motor commands to produce adaptive motor coordination.

1. vermis and the intermediate zones of the cerebellar cortex
2. spinocerebellar tract

Cerebrocerebellum. The cerebrocerebellum is the largest functional subdivision of the human cerebellum, comprising the _____ and the ____. Its name derives from its extensive connections with the cerebral cortex, via the pontine
nuclei (afferents) and the VL thalamus (efferents). It is involved in the ____ and ____ of movements. In addition, the cerebrocerebellum is involved in the cognitive functions of the cerebellum.

1. lateral hemispheres and the dentate nuclei
2. planning and timing

Decomposition of movement.

Patients with cerebellar dysfunction are unable to
produce coordinated, smooth movements.

What happens instead? Example?

Instead, they often break the movements down into their component parts in order to execute the desired trajectory.

For example, touching one’s finger to one’s nose requires the coordinated activity of shoulder, elbow, and wrist joints. Cerebellar patients must first perform the shoulder movement, then the elbow movement, and finally the wrist movement in sequence, rather than as one, uniform motion.

2. Intention tremor.

When making a movement to a target, cerebellar patients often produce an involuntary tremor that ____ as they approach closer to the target.

Example?

increases

For example, if reaching for a cup, the hand starts out in a direct line toward
the cup; as it gets closer, however, the hand begins to move back and forth as it attempts to make contact with the cup.

3. Dysdiadochokinesia.

Patients have difficulty performing _________.

rapidly alternating movements, such as hitting a surface rapidly andrepeatedly with the palm and back of the hand.

4. Deficits in motor learning.

Cerebellar damage causes deficits in motor learning.

One prominent experimental model is the vestibuloocular reflex (VOR).

What does this reflex do?

This reflex allows us to maintain gaze on an object when the head is rotated.

A second example of cerebellum-dependent motor learning involves the execution of accurate, coordinated movements.

What is supposed to happen and happens in those with cerebellar damage?

Their motor programs had been recalibrated to use the shifted visual input.

They never made compensations.

The cerebellum may act as a ______ control system for ______ movements and a _______ controller for ____ movements.

Feedback, slow

Feedfoward, fast

In its function as a feedforward controller, the ____ may provide information regarding the desired output from motor cortex and the advance sensory information about the state of the worlds and the body. The climbing fibers may convey information about movement errors, which provides a teaching signal such that the cerebellum is more likely to produce the correct movement the next time the output is desired.

mossy fibers

The _______ may convey information about movement errors, which provides a teaching signal such that the cerebellum is more likely to produce the correct movement the next time the output is desired.

climbing fibers

The lateral vestibular nuclei are functionally analogous to the...

deep cerebellar nuclei