Basal Nuclei

function of the Basal Nuclei (ganglia)

Basal Nuclei (ganglia) consist of several groups of cell bodies that modify/adjust motor activity by sending their axonal projections to the thalamus (which will influence the motor cortex)

structures that make up the basal nuclei

-caudate
-putamen
-globus pallidus
-subthalamic nucleus
-Substantia nigra

Which nuclei make up the striatum?

-caudate
-putamen

which nuclei make up the lentiform nucleus?

-putamen
-globus pallidus

the output of the basal nuclei is via

the globus pallidus. .

corpus striatum is made up of?

-caudate
-putamen
-globus pallidus

striatum + lentiform nucleus

the caudate nucleus makes the lateral wall of

most of the lateral ventricles

Activation of the direct Basal nuclei pathway causes

increased motor cortex activity and thus increased movement

Cerebral cortex-->Striatum (caudate+Putamen)-->Globus Pallidus(inhbit); function by disinhibition (Stop the stopper)

Activation of the indirect Basal nuclei pathway causes

a decrease in motor cortex activity and decreased movement

globus pallidus inhibits the thalamus; goes through subthalamic nucleus

Lesions of the striatum

Hypokinetic disturbances

lose connections between the striatum and globus pallidus; allows globus pallidus to inhibit VL of thalamus--> decreased motor activity

akinesia

impairment in the INITIATION of movement

bradykinesia

decrease in the velocity and amplitude of movement

really is activation of the antagonist muscles and not really a decrease in muscle activity

Parkinson disease

a hypokinetic disorder
-both akinesic and bradykinesic disturbances
-caused by the loss of Dopaminergic neurons in the substantia nigra

Parkinson disease: etiology

loss of Dopaminergic neurons in the substantia nigra

Onset of Parkinson disease

45-65 years

signs/symptoms of Parkinson disease include

-slight asymmetrical gait
-vague clumsiness of the hands
-decreased eye blinking, blank stare
-decreased arm swing
-tremors at rest, pill rolling movements with fingers
-shuffling of feet when starting to move

tremors at rest, pill rolling movements with fingers associated with what disease?

Parkinson Disease

decreased arm swing associated with what disease?

Parkinson Disease

Treatments for Parkinson Disease

-L-Dopa with carbidopa
-surgery of the globus pallidus or ventral thalamus
-implant electrodes in thalamus, globus pallidus, subthalamus

3 main types of hyperkinetic disturbances (dyskinesias)

-Ballismus
-Choreiform movements
-Athetoid movements

Ballismus

-seen as hemibalism because occurs on one side of the body
-an uncontrolled flinging of the upper or lower extremity
-occurs from a lesion of the subthlamic nucleus on the contrlateral side

what lesion causes Ballismus/hemibalism

lesion of the subthalamic nucleus in the contrlateral side

Choreiform movements

-irregular, brisk, dance-like movements of the limbs, may also occur in the face
-decrease in muscle tone

think choreograph dancing

what lesions cause choreiform movements?

indirect Basal nuclei pathway lesion
-seen in patients with Huntington's disease, or overtreated Parkinson's disease

Athethoid movements

-writing of distal portions of the extremity, slow writhing movements-more common in upper extremity and hands and face

athetoid movements are a lesion of

direct Basal nuclei pathway

When sleeping what does the globus pallidus inhibit?

Thalamus: VA & VL

Inhibit movment

Huntingon disease

a genetic disorder that causes hyperkinetic disturbances
-Onset of disease is 35-40 years of age, death occurs within 10-15 years thereafter
-There is a 90% loss of striatal (caudate and putamen) neurons and a loss of the neurotransmitter ACH

Huntingon disease: pathophysiology/lesion

a 90% loss of striatal (caudate and putamen) neurons and a loss of the neurotransmitter ACH

early symptoms of Huntingon disease

-absentmindedness
-irritability
-depression
-clumsiness, falls

Later symptoms of Huntingon Diseases

-choreiform movements
-cognition and speech decline
-severe dementia
psychological disorders

Sydenham's chorea

Huntingon for kids
-consequence of rheumatic fever caused by a streptococcal infection
-occurs 6 months after infection and lasts 3-6 weeks
symptoms include:
-chorea that is flowing and restless
-muscular weakness
-hypotonia
-may also have behavioral problems: OCD, ADD, irritability