Week 4 - The Cerebellum Flashcards
(38 cards)
why does the cerebellum have more neurons than the rest of the nervous system combined?
all the granule cells in the granule layer
what are the 3 functional cerebellar zones, their cortex regions, and human/mammalian deep nuclei nomenclature?
midline - in vermis; fastigial/fastigius or medialis, and vestibular/vestibularis
intermediate - in paravermal hemisphere; globose/interpositus anterior and emboliform/interpositus posterior
lateral - in lateral hemisphere; dendate/dentatus or lateralis
what are the putative motor and cognitive functions for the midline cerebellar zone?
motor: balance, eye movement, reflexes
cognitive: autonomic arousal, limbic regulation
what are the putative motor and cognitive functions for the intermediate cerebellar zone?
motor: sensorimotor integration, movement execution
cognitive: simple verbal responses to commands
what are the putative motor and cognitive functions for the lateral cerebellar zone?
motor: preparation and planning of movements, fine motor dexterity, eye movements, imagined movements
cognitive: verbal association, rule-based learning, working memory, problem-solving, monitoring performance, temporal perception
what are the 3 cerebellar zones that can be defined based on the source of strongest inputs?
spinocerebellum/paleocerebellum - medial (includes vermis)
vestibulocerebellum/archicerebellum - inferior (nodulus and flocculus)
cerebrocerebellum/neocerebellum - lateral
what are the 3 basic elements of the cerebellum? what are their components?
- cerebellar cortex (granule, Purkinje, and molecular layers)
- deep cerebellar nuclei (output structures)
- large white matter tracts (connect cerebellum with other structures)
what are the 6 main types of neurons in the cerebellar cortex?
granule, Golgi, Purkinje, stellate, basket, and Lugaro
what are the neurons in deep cerebellar nuclei?
only two: projection neurons and local interneurons
what are non-neuronal cells in cerebellum?
- radial/Bergmann glial cells (in Purkinje and molecular layers of cortex)
- bushy astroglia (in granule layer)
- oligodendrocytes (in white matter)
what are the cells in the 3 cerebellar layers?
granule (inner): granule cells, mossy fibers, Golgi cells, climbing fibers, and Purkinje cell axons
Purkinje (middle): Purkinje cell, Golgi fibers
molecular (outer): Stellate cells, basket cells, parallel fibers, Purkinje dendrites
where do climbing fibers come from and where do they go?
come from inferior olive, and twirl around Purkinje cells
what are the 3 basic types of evidence used to determine types of functions that the cerebellum is involved in?
- anatomical data to define what areas of the brain participate in cerebellar circuits, and thus what types of signals the cerebellum is likely to process
- physiological data from imaging studies and recordings of cerebellar cells have indicated which cerebellar regions and neurons are active during specific types of tasks
- data from clinical, pathological, and behavioral studies have revealed what the functional consequences of cerebellar damage are
what is the main output cell of the cerebellar cortex?
Purkinje cell
-inhibit deep nuclei that powerfully facilitate thalamus and motor cortex or other brainstem motor nuclei to facilitate movement
what kind of action potentials do Purkine cells fire?
simple spikes and complex spikes
what are simple spikes?
typical neuronal APs produced by mossy fiber activation of granule cells, leading to parallel fiber activation of Purkinje cells
- neuron’s membrane voltage changes from -50 mV to +50 mV, then returns to resting membrane potential in less than 3 ms whenever sum of inputs from other parallel fibers exceeds threshold voltage
- occur in predictable fashion w/ variety of volitional movements (arm, head/neck, eye movements)
- related to specific aspects of movement (moment to moment changes in behavior)
what is “efference copy” or “reafference”?
moment to moment changes in behavior, related to simple spikes of Purkinje cells
what are the 4 major precerebellar spino/medulo cerebellar tracts?
- dorsal spinocerebellar
- ventral spinocerebellar
- cuneocerebellar
- rostral spinocerebellar
dorsal spinocerebellar tract
- type of info
- body parts
- arises from
reafference info for legs and trunk, from Clarke’s nucleus
ventral spinocerebellar tract
- type of info
- body parts
- arises from
efference copy info for legs/trunk, from ventral horn
cuneocerebellar tract
- type of info
- body parts
- arises from
reafference info for arms from external cuneate nucleus
rostral spinocerebellar tract
- type of info
- body parts
- arises from
efference copy info for arms from ventral horn
what are complex spikes?
neuron’s membrane voltage increases rapidly, but stays elevated for extended period of 20+ milliseconds
- while potential is elevated, can fire ~5 APs in 1:1 relationship w/ arrival of APs on climbing fibers
- -thus, single AP from inferior olive causes profound and long-lasting depolarization in membrane potential of Purkinje cell
- typically occurs once/twice per second, and reliably produced by stimuli to distinct patches of skin
what are error/unexpected signals in regards to complex spikes?
complex spiking can be related to the occurrence of unexpected stimuli