Lecture 3 - Cerebellum Flashcards
Modulatory systems
- Neurotransmitter synthesis occurs in a set of well-defined nuclei
- Projections are diffuse and do not follow a map
Dopamine syntehsized where
Substantia nigra
Ventral tegmental area (VTA)
VTA axons go where
Cortex (decision making, reward, etc)
Substantia nigra axons go where
Basal ganglia (motor control)
Dopamine and Parkinson’s disease
In Parkinson’s substantia nigra neurons die – patients have diminished substantia nigra
Example of a type of fragile neuron
Substantia nigra neurons
Norepinephrine synthesized where
Locus coeruleus
Norepinephrine is implicated in what
Arousal, stress, attention, memory
Serotonin synthesized wherw
Raphe nuclei
Serotonin is implicated in what
Mood, memory, and pain supression
Serotonin drug target
Acted upon by many antidepressants and anxiolytics (like SSRIs)
Cerebellum meaning
Little brain
T/F: More than half the neurons in your brain are in the cerebellum
True
Uniqueness of cerebellum
- Cytoarchitecture is the same all over (size/number of layers)
- Is conserved in different animals
Cerebellum responsible for what
QUALITY CONTROL
(error processing or error related feedback)
Process in cerebellum
- Upper motor neuron (first neuron in corticospinal tract) in primary motor cortex synapses on lower motor neuron to implement motor command
- Copy of motor command sent to cerebellum
- Proprioceptive information sent to cerebellum
- Cerebellum compares command to actual motion and then sends feedback to motor cortex (this was your plan and this was what happened … do they match… likely NO)
Triangle shaped hole in sagittal view
Fourth ventricle
White matter in cerebellum
Called arbor vitae
On the inside
Gray matter in cerebellum
Called cerebellar cortex
On the outside
ALWAYS gray matter is what
Cell bodies
ALWAYS white matter is what
Axons
3 anatomical subdivisions of the brain
Flocculonodular lobe
Anterior lobe
Posterior lobe
Flocculonodular lobe
- Oldest evolutionarily
- Smallest
- aka vestibulocerebellum
- roles in balance and eye movement
Flocculonodular lobe input
From vestibular nuclei
Flocculonodular lobe output
To fastigial nuclei and vestibular nuclei, and then to lower motor neurons
Anterior lobe
- aka spinocerebellum
- roles in movement coordination and motor execution (walking)
Anterior lobe input
From propioception
Anterior lobe output
To interposed nuclei, then to descending motor pathways
Posterior lobe
- aka cerebrocerebellum or neocerebellum
- roles in social cognition (memory)
- biggest
Posterior lobe input
From cortex
Posterior lobe output
To dentate nucleus, then to thalamus, and cortex
Which part of the cerebellum is most connected to cortex
Posterior lobe
3 deep nuclei
Fastigal
Interposed
Dentate
Fastigal nucleus
- Output of flocculonodular lobe
Interposed nucelus
- Output of anterior lobe
Dentate nucleus
- Output of posterior lobe
- Biggest
New stuff goes where in the brain
Outside (laterally)
How to identify dentate nucleus
- Bumps that look like teeth
- Bigger than the other nuclei
3 peduncles (group of axons)
Superior
Middle
Inferior
Superior peduncle
Mostly efferent
Output to cortex
Error signal/feedback
Think how can I adjust my movements to get there?
Middle peduncle
Afferent
Input from cortex via pons
Copy of command
Think where do I want to be?
Inferior peduncle
Efferent and afferent
Input about body position
Think where am I (proprioception)?
3 layers of cerebellar cortex
- Molecular layer
- Purkinje layer
- Granular layer
What layer is a single layer
Purkinje layer
Molecular layer
Axons, interneurons, dendrites of purkinje layer
Purkinje layer
Single row of cells
Granular layer
Densely packed granule cells and interneurons
Granule cells
Form parallel fibers
Purkinje cells
Project to deep nuclei
2 types of input
- Both inputs are excitatory
- Climbing fibers from inferior olive
- Mossy fibers from spinal cord, cortex via pons
Where do mossy fibers send input to
Granule cells
Cerebellar plasticity
When a climbing fiber synapse and parallel fiber synapse at the same time, the parallel fiber synapses are weakened
Marr-Albus-Ito motor learning theory
Granule cells give continuous information about what the body is doing – when body makes a movement error, the climbing fiber fires which kicks off parallel fiber synapses
If anything know this fr
Cerebellum gets a copy of your plan and gives fast feedback when you make a mistake
