6. CEREBRUM & BASAL GANGLIA

• Cerebellum


  Literally means "little brain" and is the second largest part of the brain
• Cerebellum


  • Located dorsal to brain stem, partially hidden by the large occipital lobes of the cortex
  • Consists of two large hemispheres united by midline vermis
  • Right-sided abnormalities produce symptoms on the same side of the body
• Function of cerebellum


  Evaluates how well movements initiated by motor areas in the cerebrum are actually carried out<|>Acts with the cerebral cortex to produce movement by coordinating the activities of groups of muscles<|>Helps control posture, functions below the level of consciousness to make movement smooth and steady<|>Controls skeletal muscles to maintain balance
• Internal structure of cerebellum

  • Superficial layer is the cerebellar cortex consisting of grey matter called folia
  • Deep to the grey matter are tracts of white matter called arbor vitae or "tree of life"
• Cerebellar peduncles


  3 paired cerebellar peduncles that attach the cerebellum to the brain stem, consisting of axons that conduct impulses between the cerebellum and other parts of the brain<|>Superior cerebellar peduncle connects the cerebellum to the brainstem and thalamus<|>Middle cerebellar peduncle is continuous with the pons<|>Inferior cerebellar peduncle connects cerebellum with medulla oblongata and spinal cord
• Cerebellar nuclei


  Regions of gray matter within the white matter that give rise to axons carrying impulses from the cerebellum to other brain centers and to the spinal cord
• Cerebellar lobes


  • Archicerebellum (flocculo-nodular lobe)
  • Paleocerebellum (anterior lobe)
  • Neocerebellum (posterior lobe)
• Archicerebellum (flocculo-nodular lobe)


  Earliest part of the cerebellum to develop, functions in maintenance of equilibrium and is mainly connected to the vestibular apparatus
• Paleocerebellum (anterior lobe)


  Next part of the cerebellum to develop, functions in the maintenance of muscle tone and is mainly connected to the spinal cord
• Neocerebellum (posterior lobe)


  Most recent part of the cerebellum to develop, functions in the coordination and regulation of fine delicate voluntary motor activity, particularly the coordination of fine finger movements
• Cerebellar dysfunction - Ataxia


  Persistent ataxia usually results from damage to the cerebellum, describing a lack of muscle control during voluntary movements such as walking or picking up objects
• Basal ganglia


  A region of the base of the brain, the main components being the striatum, globus pallidus, substantia nigra, nucleus accumbens, and subthalamic nucleus
• Functions of basal ganglia


  Control of voluntary motor movements, procedural learning, routine behaviors or "habits", eye movements, cognition and emotion
• Caudate nucleus


  Sends messages to the frontal lobe, responsible for informing us that something is not right and we should do something about it
• Putamen


  Involved in coordinating automatic behaviors such as riding a bike, driving a car, or working on an assembly line
• Globus pallidus


  Receives inputs from the caudate and putamen and provides outputs to the substantia nigra
• Nucleus accumbens


  Important for motivation, pleasure, and addiction, sometimes called the brain's "pleasure center"
• Substantia nigra


  An area of pigmented cells in the midbrain, responsible for producing the neurotransmitter dopamine, plays an important role in the control of movement and appears to interact in the process of addiction and brain reward circuits
• Dopamine


  Plays an important role in controlling voluntary movement, motivation and reward cycle for the brain, involved in mood and sleep regulation
• Parkinson's disease


  A slowly progressive disorder that affects movement, muscle control, and balance, caused by a lesion in the substantia nigra leading to a shortage of dopamine and symptoms such as tremor, akinesia, bradykinesia, stiffness, disturbances to posture, fatigue, sleep abnormalities, and depressed mood