Cerebellum Flashcards
What does heuristic mean?
Simpler, designed for someone to discover something
What is the basic function of the cerebellum?
It calibrates reflexes
There are two inputs for the cerebellum. What are they and what do they do?
The sensory inputs (such as vestibular, ocular, etc.), which provide the initial reflex, and the inferior olivary nuclei input, which registers unexpected results and sends modulating action potentials.
“The short loop is modulated by the long loop.”
The deep cerebellar nuclei are the __________ centers.
output (they receive the processed information from the cerebellar cortex and send axons to the brainstem and elsewhere)
The flocculonodular lobe is __________ to the anterior lobe.
caudal
Which part of the cerebellum is connected to the vestibular system?
The archicerebellum (aka the flocculonodular lobe); it is also called the vestibulocerebellum
The deep cerebellar nuclei are in the same horizontal plane as the ______________.
MCP
From outside to inside, what are the layers of the cerebellum?
Molecular layer
Purkinje layer
Granule layer (recall that the granule layer starts out external, but by the time you’re a toddler, the cells have migrated internally)
White matter
What fibers cross between the flat, nearly two-dimensional purkinje cells?
Parallel fibers
Describe the differences between climbing fibers and parallel fibers in terms of how they interact with purkinje cells.
Parallel fibers only touch a small portion of the purkinje cell –though they synapse with many different cells – whereas climbing fibers wrap around purkinje cells and make many points of contact with an individual cell. As such, climbing cells can more easily generate an action potential in purkinje fibers.
Simultaneous input from inferior olivary nucleus axons and mossy fibers leads to _____________.
long-term depression; this leads to plasticity and modulation of the relevant reflex
The ______ and ________ carry the main inputs to the cerebellum, while the ________ carries the main output.
ICP; MCP; SCP
The _________ lobe of the cerebellum is the most recent and is also called the neocerebellum.
posterior; it is also called the corticocerebellum
The paleocerebellum is also called the ____________.
anterior lobe or spinocerebellum
In cross sections, one observes that the cerebellum consists of ______________.
a three-layered cortex surrounding two deep nuclei
There are four nuclei in the cerebellum: ___________.
dentate; globose; emboliform; and fastigial
The corticocerebellum projects to the ________ nuclei.
dentate
Efferents from the vermis project to the _________ nuclei.
fastigial
The paravermis efferents project to the _________ nuclei.
globose and emboliform (together called the interpositus)
Efferents from the flocculo-nodular lobe project to the ______________.
vestibular nuclei (afferents also pass back this way)
All of the cerebellar lobes receive innervation from the _______________.
contralateral inferior olivary nucleus
The vermal zone controls ___________.
axial movements (like posture) and integration of head and eye movements
The paravermal zones control ____________.
fine-tuning of the limbs
The lateral lobes control _________________.
higher order movements of limbs such as initiation and planning
There is no somatotopic map in the _____________.
lateral lobes
There is a somatotopic map for ___________ information.
afferent (upside-down guy in the vermal/paravermal area)
Information from the cerebrum synapses on _______ nuclei before crossing.
basal pons
The paravermal regions send output to the _____________.
red nuclei (for control of distal limbs)
Ultimately, the flocculo-nodular lobe controls ____________.
axial muscles (to coordinate vestibular information with posture) and the vestibular reflex
Ultimately, the vermal zones control __________.
axial muscles (locomotion and gaze)
Cerebellar deficits are always _______________.
ipsilateral
Cerebellar deficits do not affect ______________.
sensation or muscle strength
What is dysmetria?
Past-pointing (the inability to put a limb in a desired location)
What is the HANDS Tremor mnemonic for cerebellar lesions?
Hypotonia Ataxia Nystagmus Dysarthria Stance/gait problems
Tremor (with intention)
How many granule cells are there?
10^11!! (more than the entire cerebral cortex)
Differentiate climbing fibers and mossy fibers.
Climbing fibers come from the inferior olivary nuclei
Mossy fibers come from everywhere else
Explain the pathway by which mossy fibers excite purkinje cells.
Mossy fibers connect to many granule cells and excite them. Granule cells then excite purkinje cells via parallel fibers.
Each purkinje is contacted by __________ parallel fibers and ____________ climbing fiber(s).
~200,000; 1
How does purkinje cell activation affect the deep nuclei?
It inhibits them. “The cerebellum acts as an inhibitory delay loop, with a presumed action in shaping the timing of descending motor commands.”
The only output from the cerebellar cortex is via the ____________ cells.
purkinje
Simple spikes in purkinje arise from ____________ fibers.
mossy
Complex spikes occur when ______________.
a stimulus does not match the expected outcome (i.e., the firing of inferior olivary nucleus climbing fibers)
Climbing fiber input leads to ____________.
calcium entry
The combination of mossy fiber and climbing fiber stimulus leads to ______________.
long-term depression
What separates the flocculonodular lobe from the rest of the cerebellum?
The posterolateral fissure
The cerebrocerebellum receives innervation from the ___________.
pons (but originally from the cerebrum)
Axons from the inferior olivary nucleus cross the midline ___________ and proceed through the ___________.
immediately; inferior cerebellar peduncle
Clarke’s column relays _______________.
proprioceptive information from the lower extremities
Axons from the SCP cross the midline ____________ and then synapse on the _______________.
in the brainstem; red nucleus
The pontine nuclei receive innervation from the ___________ cerebral cortex and project to the ______________ cerebellum.
ipsilateral; contralateral
In the upper midbrain, what do the SCP look like?
Mickey’s eyes!
The VA/VL are ______________.
ventral anterior nucleus of the thalamus; ventral lateral nucleus of the thalamus
The subthalamic nuclei are ____________ to the mammillary bodies.
superior and lateral
The VA/VL are __________ to the subthalamic nuclei.
superior
