Basal Ganglia Flashcards
Basal ganglia: Modulate cognitive and motor behaviour, critical for reach movements, eye movements . Not in main sensory motor pathway, but provide cognitive modulation over straight motor transformations
Basal ganglia is a collection of nuclei deep in _________, _______, and ____________
Basal ganglia is a collection of nuclei deep in telencephalon, diencephalon, and midbrain
What is the general role of basal ganglia?
Important role in cognition and motor control
What parts of the basal ganglia composes the striatum?
Caudate nucleus (CN) and putamen (P)
Functionally very similar, but anatomically in different parts of the brain
What parts of the basal ganglia composes the lentiform nucleus?
Putamen (P) and globus pallidus (GP)
Anatomically right beside each other, but functionally very different.
What two parts is the globus pallidus composed of?
external segment (GPe)
internal segment (GPi)
Functionally very different
What two parts is the substansia nigra (SN) composed of?
pars reticulata (SNpr)
pars compacta (SNpc)
functionally completely different nuclei
What areas of the basal ganglia form the main output of the basal ganglia?
internal segment of GP (GPi) and pars reticulata (SNpr)
Functionally very similar, but anatomically separate
What are the parts of the basal ganglia (we covered 5, some have multiple regions)
- Caudate nucleus (CN)
- Putamen (P)
- Globus pallidus (GP): external segment (GPe) and internal segment (GPi)
- Substansia nigra (SN): pars reticulata (SNpr) and pars compacta (SNpc)
- Subthalamic nucleus (STN), right under thalamus
What is the striatum composed of?
The caudate and the putamen. They are connected by grey matter (cellular bridges)
Caudate and putamen = striatum, the _____ to the basal ganglia
INPUT
The whole of the cortex is going to the basal ganglia except the _____________
The whole of the cortex is going to the basal ganglia except the primary sensory areas
What kind of input typically signals taking the hyperdirect pathway in basal ganglia circuit?
Magnocellular input, sudden change of something.
Describe the activity of dopamine in the basal ganglia circuit.
Snpc contains the neurons that make and release dopamine. They project and release dopamine into the caudate putamen.
- Dopamine neurons that terminate on the direct pathways GABA pathway neurons that release substance P contain a dopamine receptor called D1. D1 (First one that was discovered) leads to an increase in excitability of these neurons, making the GABA more in the output nucleus which leads to less Gaba in the thalamus.) Dopamine in the direct pathway facilitates movement coordination
- Caudate neurons projecting to the Gpe have the D2 receptors. Inhibits or reduces excitability of these neurons
- Dopamine facilitates the direct pathway and inhibits the indirect pathway. - Dopamine on: ○ D1: facilitates direct pathway. ○ D2: reduces excitability in the indirect pathway
What is the pathway of the motor loop. Cortical input? Striatum? Pallidum? Thalamus?
Primary motor, premotor, and somatosensory cortex input
Putamen (striatum)
Lateral globus pallidus, internal segment (pallidum)
Ventral lateral and ventral anterior nuclei (thalamus)
returns to primary motor, premotor, and supplementary motor cortex.
What is the pathway of the oculomotor loop. Cortical input? Striatum? Pallidum? Thalamus?
Posterior pariental, prefrontal cortex (cortical input)
Caudate (striatum)
Globus pallidus, internal segment; substansia nigra pars reticulata (pallidum)
Mediodorsal and ventral anterior nuclei (thalamus)
- Key part of output not only goes to thalamus but also inhibits the superior colliculus which is majorly involved in the cognitive control of where and when youre moving your eyes (superior colliculus generates saccadic eye movements, so this is able to control this by inhibiting it)
Then goes back to frontal eye field, supplementary eye field
What is a key part of the oculomotor loop in its relationship to the superior colliculus?
Key part of output not only goes to thalamus but also inhibits the superior colliculus which is majorly involved in the cognitive control of where and when youre moving your eyes (superior colliculus generates saccadic eye movements, so this is able to control this by inhibiting it)
able to inhibit saccade (overt) control. projects to SCi (motor), which would project to PPRF/riMLF that create the saccades, but in this case this is decreased/inhibited
review prefrontal loop and limbic loop slides dont know if its super important tho
on basal ganglia lecture, similar to the motor and oculomotor looop slides also review those
What is Parkinson’s disease? What does it affect?
- a progressive degenerative disorder
- degeneration in substansia nigra pars compacta (the dopamine neurons)
- leads to reduced dopamine release in striatum (caudate and putamen)
- as the dopamine runs down, it produces symptoms we classify as parkinsons, affecting motor function, cognitive control, emotional control, etc
- affects motor function
What are the main causes of Parkinson’s disease?
Parkinson’s disease can be caused by multiple factors, including:
Exogenous toxins – Environmental toxins (e.g., pesticides, MPTP) can damage dopamine neurons.
Oxidative stress – Excessive free radicals can lead to neuronal damage.
Genetic predisposition – Mutations in genes like LRRK2, PINK1, and PARKIN increase risk.
Infection – Some viral infections may contribute to neurodegeneration.
Drug-induced – Certain drugs (e.g., antipsychotics, MPTP) can cause Parkinson-like symptoms.
cause loss of DA neurons in SNpc
What is the primary neurodegenerative change in Parkinson’s disease?
The loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), leading to reduced dopamine levels in the striatum, which impairs motor control.
