Basal Ganglia Flashcards by Chavez Girls

The basal ganglia is not only involved in motor control, but also _________, __________, __________

Goal directed behavior, social behavior, emotions

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The basal ganglia and cerebellum adjust motor tract activity via the _________ and have no direct contacts with _______

Thalamus

Motor Neurons

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The basal ganglia predicts ______________ of actions and then ____________ the plan by inhibiting competing movements and facilitating others

Outcomes

Chooses/executes

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What are the 6 parts of the basal ganglia?

Caudate

Putamen

Globus Pallidus (int+ext)

Subthalamic Nucleus

Substantial Nigra

Cool People Go Sunday School

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What 2 structures form the striatum?

Caudate and putamen

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What 2 structures form the lentiform nucleus?

Putamen and Globus Pallidus
Lets Play Golf

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True or false: The amygdala and the red nucleus are a part of the basal ganglia

False

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Putamen

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Caudate Nucleus

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1: Globus Palidus internus

Globus Palidus Externus

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What neurotransmitter travels via the striatum (caudate and putamen), substantia nigra pars compacta, and subthalamic nucleus TO THE BASAL GANGLIA?

Dopamine

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The subthalamic nucleus is found _____ to the thalamus and _____ to the hypothalamus

Inferior to thalamus, Lateral to hypothalamus

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What neurotransmitter travels from cerebrum through corticostriatal pathways to the basal ganglia?

Examples of corticostriatal pathways: Motor, Premotor, Supplemental Motor, Prefrontal, Somatosensory, Limbic

Glutamate (Excitatory)

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What is the role of dopamine in the basal ganglia?

Role in Go pathways?

Role in No-Go pathways?

Adjusts transmission pathways between striatum and other basal ganglia nuclei?

Go pathways- excitatory

No-go pathways- inhibitory

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ACH is a _____ neurotransmitter in the basal ganglia, and serotonin is ________

ACH- Excitatory

Serotonin- Inhibitory

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What inhibitory neurotransmitter is an output from the basal ganglia to the thalamus/cortex/reticular formation/superior colliculus, and Premotor cortex and tectospinal tract

GABA (inhibitory)

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What are the 2 motor loops of the basal ganglia?

Occulomotor loop

Motor loop

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What are the non-motor loops of the basal ganglia?

Goal Directed behavior

Social Behavior

Emotion Loop

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What loops are a part of the dorsal striatal pathways?

Occulomotor Loop, Motor Loop, and Goal directed behavior loop and social behavior loop

(Everything but the emotional loop)

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What loops are in the ventral striatal pathway?

Emotional Loop (limbic channel)

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What non-motor loops are in the pre-frontal channel (which is inside of the dorsal striatal pathway)

Goal Directed behavior loop

Social Behavior Loop

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What is the loop pathway of the Goal Directed behavior loop?

Cortex (Lateral Prefrontal) -> Basal Ganglia (First to head of caudate then to Globus Pallidus Internus) -> Thalamus -> cortex

Note: This is the only one of the 3 pre-frontal loops that uses GPi

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Deficits of the goal directed behavior loop can lead to….

Decision making deficits

Inattention, poor concentration, poor short term memory

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In the goal directed behavior loop, the head of the caudate does what?

Evaluates inputs for decision making and picks the most appropriate action

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In the goal directed behavior loop, the Thalamus is responsible for…

Linking action chosen by head of caudate (Basal ganglia) and preforming the selected movement

What is the pathway of the Social Behavior Loop?

Ventral Prefrontal Cortex -> Basal Ganglia (first to the head of caudate then to the substantia nigra reticularis) -> Thalamus -> Ventral Prefrontal Cortex Note: does not include Globus Pallidus Internus or externus How to remember: Social behavior gives you dopamine so therefore the social behavior loop includes the substantia nigra

What is the role of the head of caudate in the Social Behavior Loop?

Awareness of social cues, regulates self control, determines relevant and irrelevant info

Deficits of the social behavior loop can lead to

Impulsivity, Indifference, violent behaviors, risky behaviors

What is the pathway of the emotional loop?

Medial Prefrontal Cortex -> Basal Ganglia (ventral striatum) -> thalamus -> medial prefrontal cortex Note: Goal directed behavior is lateral prefrontal cortex, social loop is ventral, emotional loop is medial Note: All loops go cortex -> BG -> Thalamus -> cortex

What part of the cortex is responsible for the: Emotional Loop? Social Behavior Loop? Goal Directed Behavior Loop?

Emotional: Medial Prefrontal Social Behavior: Ventral Prefrontal Goal Directed Behavior: Lateral Prefrontal Cortex

Deficits of the Emotional loop lead to…

Impaired reward seeking behavior/ addiction Note: L Basal ganglia stroke can lead to depression and dulling of emotion

Caudate Nucleus

Globus Pallidus

Putamen

Thalamus

What is the pathway of the Oculomotor loop

Cortex (frontal and supplementary eye fields) -> Basal Ganglia (body of caudate) -> Thalamus -> Cortex

Deficits of the Oculomotor loop will lead to

Poor saccadic eye movements

Prosaccades vs Antisaccades

Prosaccades- towards an object Antisaccades- away from an object

In the Oculomotor loop, what does the body of the caudate do?

Decides about motions of eyes and spatial attention Particularly the use of saccades

What is the purpose of the motor loop

Regulates muscle contraction, force, multi joint movement and mvmvt sequencing

What is the only loop that the caudate is not a part of

Motor loop

What is the pathway of the motor loop

Cortex (Motor and Premotor) -> Basal Ganglia (Putamen -> Globus Pallidus) -> Thalamus -> cortex

Disinhibition requires at least 2 __________ and 1 _________

2- inhibitory neurons and 1 target neuron

Disinhibition is important for ________

Fine tuning of movement

What is the output nucleus of the 3 internal pathways of the motor loop? Stop Go No-Go

All 3 use the Globus Pallidus Internus as the output nucleus Note: all 3 are needed for normal movement

The Globus Pallidus Internus _____ the motor thalamus which ______ cortical motor areas, which ______ motor neurons in SC and brainstem

Inhibits Excites Excites

Conditions that interfere with/ the basal ganglia cause either __________ or _________ movement

Excessive or insufficient

The STOP pathway is also called the……

Hyperdirect pathway

What is the fastest motor pathway?

Stop pathway/hyperdirect

In the stop pathway, the cortex sends an ______ signal to the subthalamic nucleus which then _______ the GPi

Excitatory Excites (Note: GPi is the main inhibitory output of inhibitory neurons in each loop)

In the STOP pathway, what does the GPi do once it’s excited by the subthalamic nucleus

Inhibits Motor thalamus immediately prior to movement initiation, inhibits current motor programs to stop irrelevant movements

The Go-Pathway is also called the…

Direct Pathway

In the go-pathway, the Motor areas of the cortex _____ the putamen which _______ the Globus Pallidus Internus, which sends less inhibition to the motor thalamus

Excites Inhibits

What structure can inhibit the GPi? What structure can excite the GPi?

Inhibit- Putamen Excite- Subthalamic nucleus

Free Card Slot

30 second stretch break

The no-go pathway is also called the

Indirect pathway

In the no-go pathway, the Motor cortex _______ the putamen, which ______ the external Globus Pallidus which then has less inhibition on the subthalamic nucleus, the subthalamic nucleus _________ the GPi which inhibits the motor thalamus

Excites Inhibits Excites

What pathway inhibits unwanted movements

No-go pathway Note: the STOP pathway stops current movements

What neurons compose 95% of the neurons within the striatum?

Medium Spiny Neuron

The motor loop requires ________ from the substantia nigra compacta

Dopamine Note: Dopamine in normal quantities regulates tonic inhibition from GPi to motorthalamus and other structures

The Putamen’s D1 and D2 receptors bind to ______

Dopamine

D1 receptors binding to dopamine does what?

Excites the inhibitory neurons in GPi (Inhibits GPi in GO pathway) Note: D2 pathway involves exciting GPi in No-GO pathway

D2 receptors binding to dopamine do what?

Inhibits neurons from putamen to GPe which then disinhibits the subthalamic nucleus Since the subthalamic nucleus normally excites the GPi, this pathway stimulates the GPi Note: so both D1 and D2 excite the GPi in some way

Medium spiny neurons are _______ inhibitory cells

GABAergic

What are the 3 pathways that the Motor loop regulates motor output through?

Voluntary Muscle Activity Postural and Proximal Limb Muscle Activity Walking

The motor loop controls Voluntary Muscle Activity through..

Thru motor thalamus to motor tract cell bodies in cortex ► Corticospinal, corticopontine, corticobrainstem tracts

The motor loop controls Postural and proximal limb muscle activity through.....

Thru pedunculopontine nucleus in midbrain to reticulospinal tracts to spinal motor nerves Basically the motor loop used the reticulospinal tract to control posture

The motor loop controls walking through..

Thru midbrain locomotor region to reticulospinal tracts to stepping pattern generator

What is the most common basal ganglia disorder?

Parkinsons It is an example of hypokinetic disorders Too much BG inhibition of thalamus

Hyperkinetic vs hypokinetic disorders

Hyper- Too little inhibition of thalamus by BG Hypo- Too much inhibition

Huntington’s Disease/Chorea Dystonia Tourette’s disorder Dyskinetic cerebral palsy Are all examples of what?

Hyperkinetic disorders

What is the primary mechanism of parkinsons?

Decreased dopamine output by substantia nigra leading to excessive GPi activity

What are 2 subtypes of parkinsons?

Postural Instability Gait Difficulty (PIGD) Subtype ►Bradykinesia ► Poverty of movement (Hypokineisa) ► Postural instability ► Autonomic dysfunction ► Cognitive dysfunction Tremor Dominant Subtype ►Resting tremors ► Action tremors ► Rigidity and slow movements are relatively mild

What is huntington's/Chorea disease?

Autosomal dominant hereditary disorder causes progressive degeneration of the cortex and striatum (especially putamen)

Huntington's disease causes a 90% loss of subset of GABA-ergic inhibitory neurons in putamen and caudate so less input to.....

GPe (indirect/No-Go pathway)

In Huntington's disease, Loss of excitatory output of subthalamic nucleus to _______ causing ballistic involuntary movements of limbs called Chorei-form movements: involuntary, continuous movement of the body

Globus Pallidus Internus Note: Includes motor, swallowing, and cognitive deterioration Thalamic neurons can fire randomly and inappropriately, causing the motor cortex to execute motor programs with no control by patient

What is dystonia?

Genetic, typically nonprogressive, movement disorder characterized by involuntary sustained muscle contractions, causing abnormal posture, twisting and repetitive movements

When does dystonia typically increase? When does it completely vanish?

During activity or emotional stress During Sleep

Examples of _____ dystonias include writer’s or musician’s cramp, cervical dystonia Generalized dystonias can be __________, including limbs and trunk, interfering with walking and other functions.

Focal Progressive