Anatomy & Pathways of the Basal Ganglia

These flashcards cover key concepts and mechanisms involved in the anatomy and pathways of the basal ganglia, as well as related disorders and functions in the visual system.

Direct Pathway

Facilitates movement by disinhibiting the thalamus, leading to increased activation of the cortex.

Indirect Pathway

Inhibits movement by enhancing inhibition of the thalamus, resulting in less cortical activation.

Substantia Nigra

Provides dopaminergic input to the striatum, crucial for the direct pathway.

Striatum

Part of the basal ganglia that receives excitatory signals from the cortex and sends inhibitory signals to the GPi.

Globus Pallidus Internus (GPi)

Part of the basal ganglia that normally inhibits the thalamus; its inhibition leads to disinhibition of the thalamus.

Cortex

The brain region that receives excitatory input from the thalamus and initiates movement.

Parkinson’s Disease

A condition characterized by degeneration of the substantia nigra, leading to underactivity of the direct pathway and overactivity of the indirect pathway.

Huntington’s Disease

A disorder involving degeneration of the striatum, particularly affecting the indirect pathway, leading to uncontrolled movements.

Obsessive-Compulsive Disorder (OCD)

Associated with dysfunction in basal ganglia-thalamo-cortical circuits, often involving an imbalance between the direct and indirect pathways.

ON Bipolar Cells

Activated when light increases in their receptive field center, have metabotropic glutamate receptors.

OFF Bipolar Cells

Activated when light decreases or is turned off in their receptive field center, have ionotropic glutamate receptors.

Double Dissociation

A demonstration that two cognitive functions are independent, evidenced by patients who can perform one function but not the other.

Center-Surround Organization

The arrangement in ganglion cells that helps detect contrast and edges by integrating input from bipolar cells.

Thalamus

Part of the brain that sends excitatory signals to the cortex, involved in both the direct and indirect pathways.

Dopaminergic Neurons

Neurons of the substantia nigra that release dopamine, crucial for the direct pathway's function.

Glutamate

The main excitatory neurotransmitter involved in transmitting signals from the cortex to the striatum.