Cerebellum Flashcards
Vermis
- Midline cerebellar zone
- Deep nuclei: Fastigial, vestibular
- Balance, eye movement, reflexes
- Autonomic arousal, limbic regulation
Paravermal hemisphere
- Intermediate cerebellar zone
- Deep nuclei: globose, emboliform
- Sensorimotor integration, movement execution
- Simple verbal responses to commands
Lateral hemisphere
- Lateral cerebellar zone
- Deep nuclei: dentate
- Preparation and planning of movements, fine motor dexterity, eye movements, imagined movements
- Verbal association, rule-based learning, working memory, problem-solving, monitoring performance, temporal perception
Spinocerebellum
- Vermis and paravermal hemispheres
- More inputs from spinal cord than other areas
Vestibulocerebellum
- Flocculus
- More inputs from vestibular nuclei than other areas
Cerebrocerebellum
- Lateral hemispheres
- More inputs from cerebral cortex (via pontine nuclei) than any other areas
Three basic elements of the cerebellum
- Cerebellar cortex with a granule, purkinje, and molecular layers
- Deep cerebellar nuclei
- Large white matter tracts
Six main cell types in cerebellar cortex
- Granule*
- Golgi*
- Purkinje*
- Stellate
- Basket
- Lugaro
Two main types of neurons in the deep cerebellar nuclei
- Projection neurons
- Local interneurons
Non neuronal cells in the cerebellum
- Radial or Bergmann glial cells–purkinje and molecular layers of cerebellar cortex
- Bushy astroglia–granule layer
- Oligodendrocytes–white matter
Purkinje cell
- Connects the inferior olive to the purkinje layer via climbing fibers
- Connects granule cells to purkinje layer via parallel fibers
- Projects to deep nuclei
- Inhibitory neuron
- GABA, GAD, GABA-T, zebrin, motilin
Basket cell
- Connects granule cells to purkinje layer via parallel fibers
- Projects to purkinje cell somas
- Inhibitory
- GABA, GAD
Stellate cell
- Connects granule cells to purkinje layer via parallel fibers
- Projects to purkinje cell dendrites
- Inhibitory
- GABA (?)
Golgi cell
- Connects granule cells to granular layer via parallel fibers
- Projects to granular layer cells
- Inhibitory neuron
- GABA
Granule cell
- Connects pontine and brainstem nuclei to granular layer via mossy and mossy-like fibers
- Projects to dendrites of other cerebellar cortical cells
- Excitatory!
- GABA, glutamate
Projection cell
- Connects purkinje cells to deep nuclei
- Excitatory or inhibitory
- Glutamate or GABA
- Inhibitory go to inferior olive
Interneuron cell
- Inhibitory
- GABA, glutamate
Two types of APs for purkinje cells
-Simple and complex spike
Simple spikes
- Typical neuronal action potentials
- Produced by mossy fiber activation of granule cells which in turn leads to parallel fiber activation of purkinje cells
- Depict moment to moment changes in behavior
Efference copy
- Copy of the commands for movement
- Ventral and rostral spinocerebellar tracts
Reafference copy
- A sensory feedback signal from a body part that is being issued commands for movement
- Dorsal spinocerebellar and cuneocerebellar tracts
Complex spikes
- Neuron’s membrane voltage increases rapidly and then stays elevated for an extended period (20 ms or more)
- Many APs fired (5) during this time
- Occur in 1:1 ratio with arrival of APs on climbing fibers
- Related to the occurrence of unexpected stimuli
- During and after complex spike: long term depression (refractory to parallel fiber activation) (the basis for cerebellar learning)
Asthenia
-Loss of muscle strength
Asynergia
-difficulty coordinating muscular actions
Treatment of essential tremor
- Ethanol or barbituate administraction or deep brain stimulation
- Act as glu antagonists and gaba agonists
- Treat by eliminating cerebellar modification of motor commands
