Ch 19 Basal Ganglia

Front 1

Name the 7 basal ganglia

Back 1

Putamen
Caudate nucleus
Nucleus accumbens
Globus pallidus
Subthalamic nucleus (in diencepalon)
Substania nigra (in midbrain)

Front 2

Where are the basal ganglia located?

Back 2

located deep within cerebrum, diencephalon, and midbrain

Front 3

What's the basal ganglia's job?

Back 3

The basal ganglia help to regulate the scale (size) of movements, aiding in both the inhibition and facilitation of skeletal muscle groups to ensure smooth coordination of movements

Front 4

striatum

Back 4

-composed of the globus pallidus, caudate nucleus and nucleus accumbens
-common embryionic origin, identical histological appearance, and similar connections
-mylin filaments form "stripes" inbtwn lenticular and caudate

Front 5

Lenticular or Lentiform nucleus

Back 5

-putamen and globus pallidus
-physically appposed

Front 6

Ventral striatum

Back 6

nucleus accumbens and surrounding parts that receive limbic information

Front 7

What are the two parts to the substantia Nigra?

Back 7

-a region of the basal nuclei composed of 2 parts: the compact and reticular part

Front 8

reticular part of the substantia nigra

Back 8

-a basal ganglia output nuclei
-near the cerebellar peduncle (more vental)
-similar to globus pallidus (loose packed neurons)

Front 9

compact part of the substania nigra

Back 9

-compact pigmented neurons
-dorsal
-widespread, modulatory, dopaminergic projections to other parts of the basal ganglia

Front 10

inputs to basal ganglia

Back 10

-from cerebral cortex to striatum and subthalamic nuclei

Front 11

outputs from basal ganglia

Back 11

-from globus pallidus and the reticular part of the substantia nigra
-to thalmus ventral anterior/ventral lateral nuclei and then back to cortex

Front 12

What is the importance of cortical feedback loops?

Back 12

-the basal ganglia play a role in controling processes, such as mvt, via cortical feedback loops.
-Through these inputs, BG are constantly informed about most aspects of cortical function

Front 13

How are these feed back loops set up?

Back 13

Each loop starts with a projection from the cerebral cortex goes to the basal ganglia and returns via the thalmus to the same cortical area. starting and end point of the loop dtr fx of the loop

Front 14

what is the role of the putamen in the basal ganglia circuit?

Back 14

-input projections from somatosensory and motor cortex
-output via globus pallidus & thalamus (VL/VA) to motor area
-individual neurons in the putamen fire during certain mvt
-putamen is heavily involved in mvt

Front 15

what is the role of the caudate nucleus in the basal ganglia circuit?

Back 15

- input from assoc cortex, esp prefrontal
-projects via glonus pallidus, substantia nigra and thalamus to prefrontal areas
-involved with cognitive fx such as planning

Front 16

what is the role of the vetral straitum nucleus in the basal ganglia circuit?

Back 16

--input projections form limbic areas
--output to GP the thalamus then back to limbic
-important in drive related behaviors

Front 17

describe the direct pathway sans domamine

Back 17

-UMN-->putamen (striatum)-->GP-->thalmus-->UMN
-excitatory-->inhibitory-->inhibitory--> excitatory

Front 18

In what pathway does the subthalamic nucleus play a role? What is that role?

Back 18

- indirect pathway
-side tracks info so the the STN influences output from the GP and an overall inhib results

Front 19

Describe the indirect pathway

Back 19

-UMN-->striatum-->GP-->STN-->GP-->thalmus-->UMN
-excitatory-->inhib-->inhib-->excitatory-->inhib-->excitatory
-suppresses cortical activity

Front 20

What is the primary neurotransmitter of the substantia nigra?

Back 20

-dopomine

Front 21

What are its effects in the indirect and direct pathways

Back 21

-indirect pathway, it is inhib
-direct pathway, it is excit

Front 22

Where does dopamine act to influence the direct and indirect pathway?

Back 22

at the globus pallidus

Front 23

What does lack of dopamine cause?

Back 23

-inc inhib
-dec excitatory
-overall inhib of thalmus and dec cortical activity

Front 24

Parkinson's Disease

Back 24

-characterized by rigidity and difficulty moving. eg tremors
-most common basal ganglia disorder
-substantia nigra deteriorates, no more dopamine= dec cortical output

Front 25

What are the symptoms of Parkinson's Disease?

Back 25

-bradykinesia/hypokinesia --> slow blinking, no arm movement with walking
-resting tremor
-stooped posture
-rigidity due to inc tone in all muscles

Front 26

Treatment for Parkinson's

Back 26

-Administer the depleted neurotransmitters to specific locations - L-Dopa (levodopa)
Precursor of dopamine (Dopamine can’t cross BBB)
-Injection of embryonic stem cells to try to replace the lost and damaged cells of the basal ganglia.

Front 27

What is the blood supply for the striatum?

Back 27

lenticulstriate arteries from the middle and anterior cerebral artery

Front 28

What is the blood supply of the globus pallidus?

Back 28

from anterior chordoidal artery

Front 29

What is the blood supply for the SN and STN?

Back 29

penetrating branches of the posterior cerebral artery

Front 30

What type of movement abnormalities result from basal ganglia disorders?

Back 30

Involuntary movements
Problems initiating movements
Disturbances with muscle tone

Front 31

What are the involuntary movements of hyperkinetic disorders?

Back 31

-tremors
-ballisimus
-Chorea
-athetosis

Front 32

Tremors

Back 32

- rhythmic, oscillatory, involuntary movements

Front 33

Ballismus

Back 33

uncoordinated swinging of the limbs and jerky movements

Front 34

Chorea

Back 34

-a series of nearly continuous, rapid movements of the face, tongue, or limbs
-Often resemble fragments of normal voluntary movements

Front 35

Athetosis

Back 35

-slow, writhing movements
-Most pronounced in hands and fingers (pill rolling)
-Seems to be due to damage in striatum
-Opposite end of spectrum from chorea

Front 36

Huntington's Disease

Back 36

-characterized by continuous rapid movements of the face and limbs
-dementia
-autosomal dominant
-due to degradation of the caudate nucleus

Front 37

What happens in the indirect pathway with Huntington's disease?

Back 37

less output from the striatum causes inc inhib of GP--> dec STN activity--> inc output of thalmus-->inc output of cortex (hyperkinesia)

Front 38

Hemiballismus

Back 38

-characterized by wild flailing movement of the arm on one side, due to lesions in the contralateral STN.
-causes inhib of GP, inc output of thalmus, inc output of cortex which causes hyperkinesia

Front 39

What are 2 options for treating problems in the basal ganglia?

Back 39

-DBS
-lesions in the GP or thalamic nuclei to route out the bad feedback loop. this is a tx of last resort