Basal Ganglia And Thalamus

Front 1

Describe the basal ganglia and describe the four deep brain nuclei associated with it

Back 1

Basal ganglia are a part of the extrapyramidal motor system.
1) Caudate and putamen (striatum) where afferent input goes into basal ganglia. Caudate forms the lateral walls of lateral ventricle
2) Globus pallidus: efferent outflow comes out of here
3) Claustrum
4) Amygdala: Role is related to limbic issues more than motor.

Front 2

Describe the internal capsule

Back 2

a band of fibers b/w the globus pallidus and putamen which enter and leave the cerebral cortex

Front 3

what forms the walls of the 3rd ventricle

Back 3

thalamus

Front 4

what forms the walls of the lateral ventricles

Back 4

caudate. the caudate also ends as the amygdala.

Front 5

Basal ganglia afferents;

Back 5

1) Cerebral Cortex: (4,312,6, and 8, glutamate, excitatory) lots of the fibers leave as the corticospinal tract and many go into the basal ganglia and use glutamate as a NT.
2) SN catacholamine and DA leave here. Excitatory and inhibitory action
3) Thalamus: enters into basal ganglia Excitatory
4) Subthalamic nucleus: Excitatory
All of the information that enters the basal ganglia eventually goes to the globus pallidus

Front 6

Area 8

Back 6

Frontal eye field

Front 7

Area 6

Back 7

premotor area. initation of movement starts here

Front 8

Area 4

Back 8

principal motor area

Front 9

Area 3-1-2

Back 9

primary sensory strip. if you lesion here you lose ability to feel, pain, temp, and touch

Front 10

Area 18 and 19

Back 10

Visual association areas (secondary visual areas). If lesion here you can still see a girl but you won't know that it is your daughter. you will retain vision sensation but you lose the ability to interpret it

Front 11

Area 17

Back 11

primary visual area. if lesion here you will be blind

Front 12

Area 22

Back 12

Speech comprehension/wernicke's area

Front 13

Area 41

Back 13

Primary auditory cortex

Front 14

Area 42

Back 14

Associative auditory cortex

Front 15

Area 44

Back 15

motor speech area/broca's area

Front 16

Basal Ganglia Efferents

Back 16

All output from the basal ganglia is inhibitory and uses GABA as a NT.
1) Thalamus to cortex: (one exception is there is a thalmocortical projection that is excitatory)
2) Subthalamus (to GP to cortex)
3) Red nucleus: GP inhitibs the red nucleus so if you lesions above the red nucleus get decorticate posture and unchecked flexion of upper extremeties

Front 17

Describe what the basal ganglia does?

Back 17

the basal ganglia is designed to modulate output from the cortex

Front 18

Do the caudate, putamen, or GP have any direct projections to the Spinal cord?

Back 18

no

Front 19

Describe how the Globus pallidus effects the motor system

Back 19

The globus pallidus acts as a continuous brake/inhibitory effect on the thalmocortical circuits. If you lose the globus pallidus you lose control over motor movement

Front 20

Describe how area 6: the premotor area works

Back 20

This area tells the body to fire all the muscles of the arm or leg when going to pick something up. the globus pallidus works as a brake and refines the motor movement.

Front 21

Name the two opposing forces that act on the globus pallidus

Back 21

1) Subthalamic nucleus: is excitatory to the globus pallidus. this causes the GP to fire GABA and inhibit the thalamus causing a decrease in thalamocortical excitation
2) Caudate: during movement excites the putamen which inhibits the GP and thus effectively allows the thalamus to fire.
In summary the striatum acts to lift the brake while the subthalamus applies the brake

Front 22

Describe the basal ganglia and its relationship to straital neurons

Back 22

when activated by the cortex, straital neurons fire under modulation from dopamine and acetylcholine.
Striatal neurons fire they inhibit the globus pallidus. The globus pallidus can no longer inhibit the thalamus
The thalamus then excites cortical output

Front 23

What is dyskinesias

Back 23

Tremors are known as dyskinesias. Involuntary movement is a release phenomenon. an inhibitor is now gone and the movement that was suppressed is now released

Front 24

Athetosis

Back 24

slow, worm like movements, and fluid movement not flailing. the brake is off

Front 25

Choreaform

Back 25

seen in huntington's chorea. exaggerated flailing movements, snapping movements. Without a brake, everything is all in.

Front 26

Tardive dyskinesia

Back 26

psychiatric drugs that inhibit dopamine action in striatum. Examples are haldol/prolixen. Most common in terrets facial features with twitching, lip smacking, tongue protrusion

Front 27

Parkinson's disease

Back 27

disease of basal ganglia. Dopamine loss from substantia nigra

Front 28

huntington's disease

Back 28

GABA loss from caudate

Front 29

Sydenham's chorea

Back 29

Self limited (goes away in 3-4 months) complication of strep throat/rheumatic fever. secondary small hemorrhages following strep. AKA St. Vitas dance. Immune rxn causes microinfarcts in basal ganglia of the brain.

Front 30

Hemiballism

Back 30

contralateral wild flailing caused by infarcts of the subthalamus. Self-limited dissease goes away after 3-4 months.

Front 31

Wilson's disease

Back 31

Familial disorder of copper metabolism, lesions occur in the putamen and globus pallidus . Keyser fleischer rings and copper builds in the iris. Flapping tremors are present and hepatolenticular degeneration.

Front 32

Where do projections from the corticospinal tract

Back 32

Comes from area 4: primary motor strip
area 312: primary sensory strip
area 6: premotor strip
Projections actually come form equal areas 1/3 from 4, 6, 312

Front 33

Describe the anterior and posterior limb of the internal capsule

Back 33

Anterior limb: interneuron connections
Posterior limb: more related to sensory and motor functions
All input into and out of cortex goes through internal capsule

Front 34

What does the capital FAL stand for?

Back 34

face, arm, and leg are motor systems of the internal capsule

Front 35

What does the little fal stand for?

Back 35

sensory systems face, arm, and leg

Front 36

What happens if you stroke the middle cerebral artery?

Back 36

Internal capsule supplied by small arteries off middle cerebral arteries. Generally you will get both the motor and sensory deficit contralaterally. Don't just get motor or sensory if stroke middle cerebral artery.

Front 37

Describe Lacunar infarcts/striate arties.

Back 37

hemorrhagic strokes that occur due to untreated hypertension. Generally involve striate arteries that come off the middle cerebral arteries. Striate arteries just supply a portion of the internal capsule. Present generally with a motor or sensory deficit but not both. This is b/c different arteries supply the motor arm and sensory arm.

Front 38

Area 9 and 10

Back 38

prefrontal area out in front. this is where you do prefrontal lobotomy which can help reduce aggression.

Front 39

Describe the fornix

Back 39

fornix comes out of the temporal lobes (reverse of the caudate) and goes down into the mamillary bodies. Connects the limbic system to the hypothalamus via the fornix

Front 40

Describe the thalamus's location.

Back 40

forms the lateral walls of the 3rd ventricles. there are 2 thalami present. Massa intermedia is connection b/w two thalami that is a non neural connection that might not be present in every person.

Front 41

Parts of the thalamus:
Lateral geniculate:
Medial geniculate:
Ventral posterolateral nucleus:
Ventral posteromedial nucleus:
Anterior nuclear group:

Back 41

lateral geniculate: vision
Medical geniculate: hearing
VPL: touch from lower body
VPM: touch from face and up
anterior nuclear group: goes to cingulate gyrus

Front 42

Describe where the anterior nucleus goes to

Back 42

fornix projects to the mamillary bodies project to thalamus, anterior nucleus thalamus goes to cingulate gyrus of cortex

Front 43

Dorsomedial nucleus:

Back 43

related to areas 9 and 10 of prefrontal area. Connection is to aggression. The dorsomedial nuclei neurons die when you do a prefrontal lobotomy. if lesion dorsomedial nucleus could cause same symptoms as prefrontal lobotomy

Front 44

Pulvanar

Back 44

projects to associated vision areas 18 and 19

Front 45

Describe epilepsy and how it crosses hemispheres

Back 45

Epilepsy generally starts in one hemisphere and can cross over to other hemispheres. Can cut connections b/w the right and left hemispheres to prevent epilepsy from going to other side.

Front 46

What gyrus is on the side of the calcarine sulcus? What gyri are above and below the calcarine sulcus?

Back 46

are 17 (primary visual area). Gyri above and below the calcarine sulcus are areas 18 and 19.

Front 47

Where do the lower and upper visual fields run on the calcarine sulcus?

Back 47

the lower visual field runs on top of the calcarine sulcus.
The upper visual field runs on bottom of calcarine sulcus.

Front 48

Lateral geniculate:

Back 48

Receives ipsilateral temporal retina (nasal visual field) and crossed fibers from contralateral nasal retina (contralateral temporal visual fields)

Front 49

Crossed fibers of the retina:

Back 49

Areas 1, 4 and 6 of the visual field are coming from crossed fibers

Front 50

Describe Circumventricular organs

Back 50

these are areas surrounding the ventricles.
Areas where there is no BBB have direct connection between brain and CSF.
Substance entering CSF from blood vessels in subarachnoid space can reach NS through these circumventricular organs.
External mediators can affect NS here such as fever.
Includes the area postrema and pineal gland

Front 51

Describe the pineal gland:

Back 51

Is a circumventricular organ. Receives direct connections from the hypothalamus, and sends fibers back to hypothalamus.
Produces several substances: 5 HT (seratonin), NEPI, Melatonin, TRH (Thyroid releasing hormones), LHRH (leutinizing hormone releasing hormone), SOM (somatostation hormone)
Pineal gland senses changes in daylight, circadian rhythm clock in deer/lower mammals.
This is why melatonin can be used as a sleeping aid.

Front 52

What happens if you have a tumor in pineal gland?

Back 52

results in increased secretion/action and results in delayed pubescence

Front 53

What happens if lesion of the pineal gland?

Back 53

results in in decreased secretion/action and precocious puberty/early puberty

Front 54

What does the pineal gland do in humans?

Back 54

The pineal gland inhibits an inhibitory influence on gonads and reproductive systems