Cerebellum Flashcards
Cerebellum
“Little Brain”,
13% of brain mass, contains more neurons (~50 billion) than rest of brain combined!
- We are still discovering functions of this massive info-processing structure!
For rapid, coordinated and/or ballistic movements
requiring precise aiming and timing = “Motor Programs”
- e.g. Saccades
- e.g. Learned
- e.g. Judging/responding
- Frequently depend on ongoing sensori-motor feedback, often executed w/minimum cognitive intervention
Saccades
Ballistic “jump” of eyes from one focus point to another (once begun, cannot stop)
Learned
(well-practiced) behaviors, from simple clapping to complex athletic or manual activities
Judging/Responding
to speed of moving stimuli, auditory intervals, timing of cued attention shifts etc
Receives proprioception
from Spinal Cord & sensory info (esp Visual and Vestibular) via Cranial Nerves
- Also from Cortex about planned & initiated movements; It computes details of required muscle outputs
- Projects to all major motor structures in brain
including Ventrolateral Thalamus (VLN) to Cortex
- No direct projections to Motor Neurons;
Influences signals sent along above Tracts to Cord
In Cerebellar Cortex
Parallel Fibers like wires along long rows of “telephone poles” called Purkinje Cells
- Action potentials in Parallels travel along, exciting Purkinjes, who send Inhibition down to Deep Nuclei
- Thus, timing of such outputs is coded per distance the signals travel along the Purkinjes
Purkinje Cells
Parallel Fibers like wires along long rows of “telephone poles”
Deep Nuclei
- Action potentials in Parallels travel along, exciting Purkinjes, who send Inhibition down to Deep Nuclei
when released from Inhibition, spontaneously command motor nuclei in brain
- e.g. Ultimately activating antagonistic muscle groups to start/stop each particular movement
Cerebellar neurons are particularly sensitive to
alcohol !!
- Sobriety tests include cerebellar-controlled actions like walking a straight line, touching finer to nose, etc
