NEUSCI | MOD 5 | BASAL GANGLIA AND CEREBELLUM

Basal Ganglia and Cerebellum

• ________ & _________ adjust activity in the descending UMNs, despite lack of

  direct connections with LMNs

Thalamus

• Influence movement via different pathways through the ________ to motor areas of the cerebral cortex and by connections with UMN

Basal Ganglia

• collection of nuclei located deep in the anterior telencephalon that are intimately related to the functions of the cerebral cortex

• play an important role in the control of posture and voluntary movement, predict the effects of various actions, then make and execute action plans

Thalamocortical Activity

• the overall function of the basal ganglia is to modulate __________ activity

Initiation; Suppression

• processes executive commands for the ______ of appropriate behavior and the _______ of inappropriate behavior

Caudate Nucleus

Putamen

Globus pallidus

• The basal ganglia include the following nuclei:

True

T OR F

• The subthalamic nuclei, the substantia nigra, and the red nucleus are functionally closely related to the basal nuclei but are NOT included

Corpus Striatum

• is situated lateral to the thalamus and is almost completely divided by a band of nerve fibers, the internal capsule, into the caudate nucleus and the lentiform nucleus

Caudate Nucleus

• is a large C-shaped mass of gray matter that is closely related to the lateral ventricle and lies lateral to the thalamus

Neostriatum or Striatum

• The head of caudate nucleus is continuous inferiorly with the putamen of the lentiform nucleus and is often called _____

Amygdaloid Nucleus

• The tail of the caudate nucleus is long and slender and is continuous with the body. It terminates anteriorly in the ______

Lentiform Nucleus

• is a wedge-shaped mass of gray matter whose broad convex base is directed laterally and whose blade is directed medially

Putamen

• lateral (wide end of cone)

Globus Pallidus

• medial (point of cone)

Internus (medial) section → GPi Externus (lateral) section → GPe

• The Globus Pallidus has what two sections?

• Internal (medial) section → ___

• Externus (lateral) section → ___

External Capsule

• Lentiform nucleus is related laterally to a thin sheet of white matter, the ______

Claustrum

• The external capsule separates the lentiform nucleus from which thin sheet of gray matter?

Substantia Nigra

• It is a nucleus in the midbrain named for the color of its cells.

• contains melanin, making the nucleus appear black

Compacta & Reticularis

• The substantia nigra has two parts:

Dopaminergic and Inhibitory

• neurons of the substantia nigra are _________ and _______, and have many connections to the corpus striatum

Subthalamic Nucleus

• Nucleus in the diencephalon located inferior to the thalamus and lateral to the hypothalamus

Glutaminergic and Excitatory

• neurons of the subthalamic nuclei are _______ and _______ and have many connections to the globus pallidus and substantia Nigra

Substantia Nigra pars compacta (SNpc)

• The _____________ provides essential dopamine to the striatum.

Internal Capsule

• SNpr and Gpi are separated by the ______?

Output Nuclei

• The substantia nigra pars reticularis (SNpr) and the globus pallidus internus (Gpi) are the _______ of the basal ganglia system

Caudate Nucleus and Putamen

• Which structures form the main sites for receiving input to the basal nuclei?

Spinal Cord

• The basal nuclei receive no direct input from or output to which structure?

Glutamate

• Neurotransmitter delivered by the cortical motor areas to produce excitation of the striatum

Dopamine

• Produced from the substantia nigra to the striatum adjusts signals to the output nuclei

• provide the appropriate level of inhibition to their target nuclei

Oculomotor, Executive, Behavioral flexibility and control, Limbic

• What are the four additional cortico-basal ganglia-thalamic loops (aside from the motor loop)?

Hyperkinetic and Hypokinetic Disorders

• Disorders of the basal nuclei are of two general types:

Hyperkinetic Disorder

• are those in which there are excessive and abnormal movements, such as seen with chorea, athetosis, and ballism

Hypokinetic Disorder

• include those in which there is a lack or slowness of movement

Motor thalamus, pedunculopontine nucleus (PPN), and mesencephalic locomotor region (MLR)

• The basal ganglia inhibit which three structures?

Hypokinetic Disorder

• Excessive inhibition by the basal ganglia leads to what type of disorder?

Hyperkinetic Disorder

• Inadequate inhibition by the basal ganglia leads to what type of disorder?

Athetosis

• characterized by slow, involuntary, writhing, twisting, “wormlike” movements greater involvement in the distal upper extremities is noted

Globus Pallidus

• Affected Part of Athetosis?

Chorea

• characterized by involuntary, rapid, irregular, and jerky movements involvingmultiple joints.

• Choreiform movements demonstrate irregular timing, are most apparent in the upper extremities

Corpus Striatum

• Affected Part of Chorea

Dystonia

• involves sustained involuntary contractions of agonist and antagonist muscles causing abnormal posturing (dystonic posture) or twisting movements.

• Most common in trunk and extremity musculature but also may affect the neck, face, and vocal cords

Putamen

• Affected Part of Dystonia?

Hemiballismus

• involves large-amplitude sudden, violent, flailing motions of the arm and leg of one side of the body. Primary involvement is in the axial and proximal musculature of the limb.

Subthalamic Nucleus

• Affected Part of Hemiballismus?

Choreoathetosis

• a movement disorder with features of both chorea and athetosis.

Basal Ganglia

• Affected Part of Choreoathetosis?

Bradykinesia

• decreased amplitude and velocity of voluntary movement Basal

Basal Ganglia

• Affected Part of Bradykinesia?

Tremor

• involuntary, rhythmic, oscillatory movement observed at rest (resting tremor). Resting tremors typically disappear or decrease with purposeful movement, but may increase with emotional stress.

Basal Ganglia

• Affected Part of Tremor?

Parkinson’s Disease

• The most common basal ganglia motor disorder is _______?

Akinetic/rigid, tremor-dominant, and mixed

• What are the three subtypes of Parkinson’s disease?

Parkinson’s Disease

• characterized by muscular rigidity, shuffling gait, drooping posture, rhythmic muscular tremors, and a mask-like facial expression

• The pathology in ______ is the death of dopamine producing cells in the substantia nigra compacta and acetylcholine-producing cells in the PPN

Akinesia/Hypokinesia

• absence or lack of movement

Rigidity

• increased resistance to all movement in all muscles. It is present during sleep.

Freezing (of gait)

• movements or walking abruptly ceases

Visuoperceptive impairments

• deficit in visual information

Resting Tremor

• involuntary rhythmic shaking movements of the limbs produced by contractions of antagonist muscles

Huntingtin

• This is caused by autosomal dominant mutation in either of an individual's two copies of a gene called _____.

Huntington’s Disease

• This is caused by autosomal dominant mutation in either of an individual's two copies of a gene called Huntingtin.

• This causes degeneration in many areas of the brain, most prominently in the striatum and cerebral cortex

• degeneration decreases signals from the basal ganglia output nuclei, resulting in disinhibition of the motor thalamus and PPN → excessive output

Dystonia

• Dystonias are genetic, usually nonprogressive, movement disorders characterized by involuntary sustained muscle contractions causing abnormal postures or twisting, repetitive movements

• Dystonia often increases during activity and emotional stress and vanishes completely during sleep

Focal Dystonia

• Which type of dystonia is the most common?

Vocal and Motor Tics

• Tourette’s disorder causes ______ & _____ tics

Tourette’s Disorder

• Tourette’s disorder causes vocal and motor tics.

• The tics are abrupt, repetitive, stereotyped movements including repeating syllables, words, or phrases; coughing; clearing the throat; twitching; and eye blinking

• Stress, emotional excitement, and fatigue exacerbate tics.

• Urge to tic builds during suppression

Cerebellum

• The _______ is situated in the posterior cranial fossa and is covered superiorly by the tentorium cerebelli.

• It coordinates movement and postural control by comparing actual motor output with the intended movement and then adjusting movement as necessary

• It is the largest part of the hindbrain and lies posterior to the fourth ventricle, the pons, and the medulla oblongata

Vermis

• The cerebellum consists of two cerebellar hemispheres joined by a narrow median _____

Cerebellum

• Which brain structure is known for “error correction,” integrating executive commands with sensory feedback for moment-to-moment adjustment of behavior, motor agility, and cognitive agility?

Cortex

• What is the outer covering of gray matter in the cerebellum called?

Arbor Vitae

• What is the name of the white matter in the vermis that resembles the trunk and branches of a tree?

Molecular layer

Purkinje cell layer

Granular layer

• What are the three layers of the cerebellar cortex?

Climbing and Mossy Fibers

• Which fibers provide afferents to the cerebellar cortex?

Mossy Fibers

• Originate in the spinal cord (spinocerebellar tracts) and in the brainstem

• Synapse with interneurons that convey information to Purkinje cells

• Convey somatosensory, arousal, equilibrium, and cereberal cortex motor information to the cerebellum

Climbing Fibers

• Arise from the inferior olivary nucleus in the medulla

• Synapse with Purkinje dendrites

• Convey information regarding movement errors to the cerebellum

Cortex of Vermis

• influences the movements of the long axis of the body, namely, the neck, the shoulders, the thorax, the abdomen, and the hips

Intermediate Zone

• Control the muscles of the distal parts of the limbs, especially the hands and feet

Lateral Zone

• concerned with the planning of sequential movements of the entire body and is involved with the conscious assessment of movement errors

Superior Cerebellar Peduncles

• What connects the cerebellum to the midbrain?

Middle Cerebellar Peduncles

• What connect the cerebellum to the pons?

Inferior Cerebellar Peduncles

• What connect the cerebellum to the medulla oblongata?

Anterior Lobe

• The _________ may be seen on the superior surface of the cerebellum and is separated from the middle lobe by a wide V- shaped fissure called the primary fissure

Posterior Lobe

• The _______ which is the largest part of the cerebellum, is

  situated between the primary and uvulonodular fissures.

Flocculonodular Lobe

• The __________ is situated posterior to the uvulonodular fissure

Dentate Nucleus

• is the largest of the cerebellar nuclei. It has the shape of a crumpled bag with the opening facing medially. It projects to the contralateral red nucleus and the ventrolateral (VL) thalamic nucleus.

Emboliform Nucleus

• is ovoid and is situated medial to the dentate nucleus, partially covering its hilus

Globose Nucleus

• consists of one or more rounded cell groups that lie medial to the emboliform nucleus. Together with emboliform, they collectively known as interposed nuclei. They project to the contralateral red nucleus (the origin of the rubrospinal tract).

Fastigal Nucleus

• lies near the midline in the vermis and close to the roof of the fourth ventricle; it is larger than the globose nucleus. It projects to the vestibular nuclei and the reticular formation

Vestibulocerebellum

• Which functional name corresponds to the flocculonodular lobe?

Spinocerebellun

• Which functional name corresponds to the anterior lobe of the cerebellum?

Cerebrocerebellum

• Which functional name corresponds to the posterior lobe of the cerebellum?

Vestibulocerebellum

• receives information directly from vestibular receptors and connects reciprocally with the vestibular nuclei

• Balance and equilibrium

• influences eye movements and postural muscles.

Spinocerebellum

• control ongoing movement via brainstem descending tracts; receives proprioceptive information from muscle spindles, as well as visual and auditory information

• coordinates stereotype and gross limb movements.

Cerebrocerebellum

• Coordination of voluntary movements

• Planning of movements and Timing

Cerebral cortex and from muscle, tendons, and joints

• From which structures does the cerebellum receive afferent information for voluntary movement?

Vestibular Nerve

• From which structure does the cerebellum receive afferent information for balance?

Tectocerebellar Tract

• Through which tract does the cerebellum integrate afferent information with vision?

Mossy and Climbing Fibers

• Which fibers feed afferent information into the cerebellar cortical circuitry, converging on Purkinje cells?

Executive

• _______ signals relayed from widespread parts of cerebral cortex in the frontal and parietal lobes via the pontine nuclei

Pontine Nuclei

Conveys commands for (motor) behavior

Feedback

• ________ signals from proprioceptive systems: conveys sensory information about ongoing behavior

Learning

• ________ signals derived from the inferior olivary nucleus of the medulla: facilitates adaptation (error correction)