basal ganglia

• How does the basal ganglia influence movement?

  It influences movement by acting on motor centres like the cerebral cortex.
• Where are the basal ganglia located?

  They are located in the forebrain.
• What are the main components of the basal ganglia?

  • Caudate nucleus
  • Putamen (striatum)
  • Globus pallidum
• Which nuclei are associated with but not part of the basal ganglia?

  Subthalamic nuclei and substantia nigra.
• What are the functions of the basal ganglia?

  • Selecting appropriate movements
  • Initiating internally generated movements
  • Reinforcement learning
  • Planning and executing complex motor strategies
  • Cognition and emotional behaviour
• From where does the striatum receive input?

  It receives input from almost all areas of the cerebral cortex.
• How do different areas of the cerebral cortex target the striatum?

  Different areas target different parts of the striatum.
• Which cortical areas project to the caudate nucleus?

  Association areas and frontal eye fields.
• Which cortical areas project to the putamen?

  Sensory and motor cortical areas.
• What are the characteristics of striatal medium spiny neurons?

  • Key neurons of the basal ganglia
  • Receive input from thousands of cortical cells
  • Inhibitory projection neurons
  • Receive most cortical inputs to basal ganglia
• What is the role of the direct pathway in the basal ganglia?

  It activates movement by disinhibiting GP and SNr to increase thalamic output.
• How does the indirect pathway function in the basal ganglia?

  It inhibits thalamic activity.
• What is the firing rate of the globus pallidus and substantia nigra?

  They are tonically active at 100 Hz.
• What is the effect of dopamine from the substantia nigra on the direct pathway?

  It increases dopamine transmission through D1 receptors.
• What is the effect of dopamine from the substantia nigra on the indirect pathway?

  It decreases dopamine transmission through D2 receptors.
• What movement deficits are associated with an imbalance in dopamine receptors in Parkinson's disease?

  Movement deficits include tremor, rigidity, and bradykinesia.
• What are the symptoms of basal ganglia disorders?

  • Tremor when resting
  • Chorea (involuntary movement)
  • Rigidity (posture and muscle tone disorder)
  • Dystonia (involuntary muscle contractions)
  • Bradykinesia (slowness of movement)
  • Akinesia (difficulties in initiating movement)
  • Parkinson’s disease (hypokinetic disorder)
  • Huntington’s disease (hyperkinetic disorder)
  • Hemiballismus (hyperkinetic disorder)
• What is the treatment for Parkinson's disease?

  Levodopa.
• What does a PET scan show after levodopa treatment in Parkinson's patients?

  It shows an increase in dopamine activity in the basal ganglia.
• How do the direct and indirect pathways function in relation to each other?

  • They work synergistically and complementarily.
  • Calcium levels increase in both pathways during movement initiation.
• What happens to calcium levels in the indirect pathway when movement is initiated?

  Calcium levels still increase, but not as much as in the direct pathway.