Basal Ganglia and Cerebellum Flashcards

Question

Ventral Anterior Nucleus

Answer 1

*Receives most of input from the basal ganglia Especially the medial globus pallidus and substantia nigra, parts reticulata. *Projects to premotor cortex including the supplementary motor area of the frontal lobes ***Involved in planning and initiating movements.

Answer 2

*Receives input from the CEREBELLUM Small input from the basal ganglia to the rostral part of the VL, as well. Projects to the primary motor area, area 4, of the precentral gyrus and also has a smaller projection to premotor areas. *Thus involved in MOTOR FEEDBACK from the cerebellum and basal ganglia to the cerebral cortex -Along with ventral anterior nucleus ****Coordination, planning, learning of movement

Answer 3

Ventral Anterior Nucleus, Ventral Lateral Nucleus .... idk some other stuff?

Answer 4

* substantia nigra pars reticulata --> superior colliculus (head and eye movements) * external globus pallidus --> subthalamic nucleus --> internal globus pallidus * internal globus pallidus --> ventral anterior and ventral lateral nuclei of dorsal thalamus --> frontal cortex (premotor and primary motor) The medium spiny neurons of the caudate and putamen release GABA onto their targets when they are excited by inputs Inhibiting the inhibitors = disinhibition Caudate --> substantia nigra pars reticulata --> superior colliculus (head and eye movements) Putamen --> external globus pallidus --> subthalamic nucleus --> internal globus pallidus Putamen --> internal globus pallidus --> ventral anterior and ventral lateral nuclei of dorsal thalamus --> frontal cortex (premotor and primary motor) slide 23! look at the colors of the arrows

Answer 5

FALSE Globus pallidus and substantia nigra pars reticulata have lots of spontaneous activity Are constantly and tonically inhibiting their target structures because they release GABA (-caudate and putamen are NOT spontaneously active, have to wait to be activated)

Answer 6

Remember, in the absence of movement intention, the medium spiny neurons are silent If you are not intending to move, you do not want to be moving So the baseline state is inhibition of upper motor neuron circuitry When you want to move, the medium spiny neurons get all firey and tell the inhibitory cells to stop it --> disinhibition of motor thalamus, superior colliculus, other things --> disinhibition of upper motor neurons  movement permitted to occur Also probably why the medium spiny neurons start getting active BEFORE you execute a movement

Answer 7

At Baseline: Globus pallidus --> prevents movement by inhibiting the motor thalamus (which is fundamentally good) Time to Move: Cortex- “I like to move it, move it” Striatum- “You like to move it, move it” Globus pallidus- “If you insist… I will just be quiet.” Motor thalamus- “I like to move it, move it” Upper motor neurons: “I like to move it, move it” Lower motor neurons: “I like to MOVE IT”

Answer 8

Globus pallidus --> holding back the movement party by inhibiting the motor thalamus (which is fundamentally good)

Answer 9

Cortex- “I like to move it, move it” Striatum- “You like to move it, move it” Globus pallidus- “If you insist… I will just be quiet.” Motor thalamus- “I like to move it, move it” Upper motor neurons: “I like to move it, move it” Lower motor neurons: “I like to MOVE IT”

Answer 10

*Superior colliculus- influence head and eye movements Secondary influence on eye movement comes from substantia nigra pars reticulata connections to relay neurons in the mediodorsal and ventral anterior thalamic nuclei, which project to the frontal eye field regions of the premotor cortex This connection through the thalamus is a mechanism to facilitate or suppress inputs to circuits of upper motor neurons

Answer 11

Direct Pathway and indirect pathway

Answer 12

* medium spiny neurons of striatum --> internal globus pallidus JOB: release tonic inhibition of the thalamic neurons connected to upper motor neurons Way for basal ganglia to initiate intentional movement

Answer 13

Indirect Pathway: select group of medium spiny neurons of striatum --> lateral division of globus pallidus (external segment) External segment --> internal segment and subthalamic nucleus Subthalamic nucleus also gets excitatory projections from cortex Subthalamic nucleus --> internal segment of globus pallidus and substantia nigra pars reticulata

Answer 14

Job: ANTAGONIZE the activity of the direct pathway to help open and shut the gates that start and stop movements

Answer 15

* Subthalamic neurons use GLUTAMATE in their synapses with the globus pallidus and substantia nigra * Activate indirect pathway --> excitation of globus pallidus and substantia nigra cells --> release GABA in response --> INCREASES INHIBITION WITHIN THE BASAL GANGLIA Helps to: Suppress competing motor programs Select proper motor program Still do not fully understand how this all works together

Answer 16

Remember: The caudate and putamen receive different streams of information from different regions of the cortex The output from the caudate and putamen is segregated Some of the projections to the basal ganglia are topographically mapped (visual and somatosensory) and some are overlapped (those from more interconnected or association regions) There are rostrocaudal bands of cells that seem to be concerned with different parts of the body and the movement of that part

Answer 17

*Substantia nigra pars compacta cells release dopamine Receive direct inputs from medium spiny neurons of striatum Sends dopaminergic projections back to the medium spiny neurons End result? Complex and depends on type of dopamine receptor expressed *D1: increase cAMP and increases excitability (basically excitatory) *D2: work with inhibitory G-proteins to decrease cAMP (basically inhibitory) Receptors are on the shafts of the dendritic spines, which is a good place to modulate responses to cortical input Dopamine to spiny cells that project to internal globus pallidus as part of the direct pathway is excitatory through D1 Dopamine to spiny cells that project to the external globus pallidus as part of the indirect pathway is inhibitory through D2

Answer 18

Parkinson’s disease:

Answer 19

degeneration of the dopaminergic neurons in the substantia nigra pars compacta * Symptoms: bradykinesia (slowness of movement), rigidity of neck and extremities, minimal facial expression. Hypokinetic = decreased voluntary movement * Lose the effects of dopamine on movement (which was enhancing direct pathway and decreasing responsiveness of indirect pathway - Direct pathway  results in disinhibition of motor thalamus - Indirect pathway  reinforces inhibition of motor thalamus * Results in abnormally high inhibitory outflow to the motor thalamus

Answer 20

Huntington’s disease is what type of movement disorder Insufficient tonic output from pallidum --> unwanted movement

Answer 21

* gradual onset of defects in behavior, cognition, and movement; genetic, progressive, and results in death While it is a movement disorder, the first symptoms are usually an increase in irritability, suspiciousness, and/or impulsive behavior Movement symptoms: rapid, jerky (“dancelike”) motions with no purpose; no weakness or ataxia Selective atrophy of the caudate and putamen (medium spiny neurons), with some additional degeneration in the frontal and temporal cortices External globus pallidus loses inhibitory input  reduces subthalamic nucleus excitatory input to internal globus pallidus --> reduced inhibitory outflow

Answer 22

The Little Brain: -it is pretty big *Approximately 10% of the brain’s volume Contains over 50% of the total number of neurons in the brain

Answer 23

Yes, but she is confusing me | -Considered a motor structure

Answer 24

* Maintenance of Balance and Posture * Coordination of Voluntary Movements Majority of the cerebellum’s outputs are to parts of the motor system. Motor commands are not initiated in the cerebellum The cerebellum MODIFIES the motor commands of the descending pathways to make movements more adaptive and accurate.

Answer 25

Important for making postural adjustments in order to maintain balance. Input from vestibular receptors and proprioceptors Modulates commands to motor neurons to compensate for shifts in body position or changes in load upon muscles.

Answer 26

Cerebellar damage leads to impairments in motor control and posture Patients with cerebellar damage suffer from balance disorders, and they often develop stereotyped postural strategies to compensate for this problem (e.g., a wide-based stance).

Answer 27

Most movements are composed of a number of different muscle groups acting together in a temporally coordinated fashion. Coordinate the timing and force of these different muscle groups to produce fluid limb or body movements. -example: doing a cartwheel

Answer 28

* Coordination of Voluntary Movements * Maintenance of Balance and Posture- a cartwheel * Motor Learning- hitting a baseball

Answer 29

Plays a major role in adapting and fine-tuning motor programs to make accurate movements through a trial-and-error process (e.g., learning to hit a baseball).

Answer 30

slide 43 Cerebellar deep nuclei and cerebellar cortex

Answer 31

Two major parts: Cerebellar deep nuclei and cerebellar cortex

Answer 32

-of the Cerebellum the deep nuclei are the main way info gets OUT of the cerebellum *Sole output structures of the cerebellum, as a whole Axons leave the cerebellum Almost all of the output of the cerebellum is through the deep nuclei

Answer 33

FALSE | *Lesions of cerebellar deep nuclei are the same as complete lesion of the entire cerebellum

Answer 34

- orienting - vigilance - positional-autonomic - oromotor - posturomotor slide 46

Answer 35

-of the Deep Cerebellar Nuclei *input from the intermediate zone and from cerebellar afferents that carry spinal, proximal somatosensory, auditory, and visual information. They project to the contralateral red nucleus (rubrospinal tract).

Answer 36

-of the Deep Cerebellar Nuclei largest of the cerebellar nuclei; input from the lateral hemisphere and from cerebellar afferents that carry information from the cerebral cortex (via the pontine nuclei). It projects to the contralateral red nucleus and the ventrolateral (VL) thalamic nucleus.

Answer 37

outside the cerebellum in the medulla; functionally equivalent to the cerebellar nuclei because their connectivity patterns are identical to the cerebellar nuclei.

Answer 38

Vestibular nuclei

Answer 39

Highly convoluted sheet of tissue that encases the cerebellar deep nuclei Contains almost all the neurons in the cerebellum. Intricate pattern of folds and fissures that characterize the cerebellar cortex

Answer 40

Cerebellar Cortex

Answer 41

Vestibulocerebellum Spinocerebellum Cerebrocerebellum

Answer 42

-a Functional Subdivision of the cerebellum the oldest part of the cerebellum Involved in vestibular reflexes (such as the vestibuloocular reflex) and in postural maintenance.

Answer 43

-a Functional Subdivision of the cerebellum (VERMIS and the intermediate zones, as well as the fastigial and interposed nuclei): major inputs from the spinocerebellar tract. Its output projects to rubrospinal, vestibulospinal, and reticulospinal tracts Involved in the integration of sensory input with motor commands to produce adaptive motor coordination. Only part to get direct input from spinal cord

Answer 44

-falls under the Spinocerebellum Most medial portion Concerned with movements of proximal muscles Regulates certain types of eye movements

Answer 45

(lateral hemispheres and the dentate nuclei): largest subdivision *Extensive connections with the cerebral cortex, via the pontine nuclei (afferents) and the VL thalamus (efferents)

Answer 46

Three fiber bundles carry the input and output of the cerebellum.

Answer 47

Three fiber bundles carry the input and output of the cerebellum.

Answer 48

The inferior cerebellar peduncle (also called the restiform body) primarily contains afferent fibers from the medulla, as well as efferents to the vestibular nuclei. Most complex

Answer 49

(also called the brachium pontis) primarily contains afferents from the pontine nuclei. One of the largest pathways in the brain (>20 million axons on each side)

Answer 50

(also called the brachium conjunctivum) primarily contains efferent fibers from the cerebellar nuclei, as well as some afferents from the spinocerebellar tract. Axons coming mostly from the deep cerebellar nuclei and go to motor thalamus and upper motor neurons in the superior colliculus

Answer 51

Inputs to the cerebellum are conveyed primarily through the inferior and middle cerebellar peduncles Arise ipsilaterally

Answer 52

Outputs are conveyed primarily through the superior cerebellar peduncle. Outputs go ipsilaterally

Answer 53

*indirect: from one side of the cortex to the other side of the cerebellum *Also gets lots of sensory information Axons from vestibular portion of CN8, and axons from vestibular nuclei in the pons and medulla Go to vestibulocerebellum Somatosensory relay neurons in the dorsal nucleus of Clarke in the spinal cord and external cuneate nucleus in medulla Relay neurons carrying proprioceptive info from the body Go to spinocerebellum Face proprioceptive info sent via the mesencephalic trigeminal nucleus Helps cerebellum figure out where your body and body parts are in space Visual and auditory signals also relayed to cerebellum to supplement the proprioceptive information *Somatosensory input is somewhat topographically mapped in the spinocerebellum Maps are fractured, in that, each small area of the body is represented multiple times by spatially separated clusters of cells rather than on a single, continuous map *Vestibular and spinal inputs remain ipsilateral -Right cerebellum concerned about the right… Cerebellum is generally concerned about same side things *Receives modulatory inputs from the inferior olivary nucleus (inferior olive)

Answer 54

cerebral cortex

Answer 55

*Major destination: cerebrocerebellum

Answer 56

*the deep nuclei are the main way info gets OUT of the cerebellum *Cerebellar cortex projects to deep cerebellar nuclei Deep nuclei also get input from different part of the cerebellar cortex Basically, outputs are to the cerebral cortex, upper motor neurons, and sometimes lower motor neurons ``` Dentate nuclei Fastigial Nuclei Interposed Nuclei Vestibular nuclei: (outside the cerebellum in the medulla) (MIGHT HAVE MISSED SOME) ```

Answer 57

-a projections from the cerebellum *Input: Mostly info from cerebrocerebellum Output: premotor and association cortices involved in planning and initiating movement Output exits through the superior cerebellar peduncle, crosses the midline, and relays first in VL thalamus *On the way to the thalamus, sends axons to eye-movement-related upper motor neurons in superior colliculus and to the red nucleus Red nucleus --> inferior olive Serves as feedback onto cerebellar inputs Important for adaptive functions of motor learning

Answer 58

-a projection from the cerebellum Fastigial Nuclei Input: spinocerebellum Output: nuclei of the reticular formation and vestibular complex Outputs sent through the inferior cerebellar peduncle *Influence pathways controlling axial and proximal limb musculature

Answer 59

-a projection from the cerebellum Interposed Nuclei Input: spinocerebellum Output: thalamic circuits that project to motor regions concerned with volitional movement of the limbs Outputs sent through the superior cerebellar peduncle In non-human primates, also send axon collaterals to the rubrospinal tract Also output to superior colliculus to modulate eye movement (crosses midline)

Answer 60

-a projection from the cerebellum Vestibular nucleus Input: vestibulocerebellum Output: vestibular nuclei in the brainstem, which govern movement of eyes, head, and neck in response to changes in head placement Outputs sent through the inferior cerebellar peduncle Vestibulocerebellum also sends out direct projections to the vestibular nuclei -NOT technically in the cerebullum (I THINK!)

Answer 61

Also have closed loops where outputs are sent through the thalamus to non-motor areas of the cortex that provided initial inputs These closed loops permit the cerebellum to regulate its own input May influence coordination of non-motor programs (ex- problem solving)

Answer 62

Inputs to the cerebellar cortex synapse on the Purkinje cells… eventually Largest of these pathways: cerebral cortex --> pontine nuclei --> contralateral cerebellum *MOSSY FIBERS * Axons of granule cells = parallel fibers * Parallel fibers form excitatory synapses on the dendritic spines of Purkinje cells * The granule cells send axons up toward the cortical surface and each axon bifurcates in the molecular layer, sending a collateral in opposite directions. * Parallel fibers, run parallel to the folds of the cerebellar cortex, where they make excitatory synapses with Purkinje cells along the way.

Answer 63

(Circuits within the Cerebellum) * Originate in the pontine nuclei, the spinal cord, the brainstem reticular formation, and the vestibular nuclei * Collateral branches that form excitatory connections on neurons in the deep nuclei AND on the granule cells of the cerebellar cortex * Each mossy fiber innervates hundreds of GRANULE CELLS.

Answer 64

Axons of granule cells =

Answer 65

*Big cells with massive dendritic trees *Essentially the only output from the cerebellar cortex GABAergic Each Purkinje cell has dendrites positioned to receive input from ~200,000 parallel fibers Each parallel fiber can contact tens of thousands of Purkinje cells *Purkinje cells also receive direct input onto their dendrites (not dendritic spines) from climbing fibers

Answer 66

Called climbing fibers because their axons climb and wrap around the dendrites of the Purkinje cell like a climbing vine and make multiple synapses ******Each Purkinje cell receives a single, extremely powerful input from a single climbing fiber. ******** *Each climbing fiber contacts only 10 Purkinje cells on average, making ~300 synapses with each Purkinje cell. Restricted, but extremely powerful, excitatory input onto Purkinje cells. *Purkinje cells are primary output of cerebellar cortex, so climbing fibers have a lot of power on what comes out *So, what do Climbing Fibers do? -Error signals -May serve to provide a “motor clock” function in the initiation and timing of movements “Climbing fibers evoke complex spikes immediately, which fits perfectly the high temporal precision required for the cerebellum to initiate or coordinate muscles” (Zang and Schutter, 2019) Drive cerebellar learning

Answer 67

Purkinje cells send inhibitory input to the deep cerebellar nuclei Deep cerebellar nuclei also get excitatory input from collaterals of mossy and climbing fibers The inhibitory projections of Purkinje cells help to sculpt the discharge patterns of the deep nuclei

Answer 68

Inhibitory (GABAergic) interneurons which modulate the inhibitory activity of Purkinje cells Inhibiting inhibition Basket cells: most powerful of the inhibitory interneurons Stellate cell: another local circuit neuron; receives input from parallel fibers and can also inhibit Purkinje cells Golgi cells: receive input from parallel fibers and provide an inhibitory feedback to the granule cells that gave rise to the parallel fibers

Answer 69

* Deep excitatory loop: | * Cortical inhibitory loop:

Answer 70

*Deep excitatory loop: mossy fiber and climbing fiber collaterals drive activation of neurons in the deep cerebellar nuclei Input converging on the source of the final output

Answer 71

The modulation of the cerebellar cortex on the output of the cerebellum may be important for motor learning Learned adjustments to movement amplitude and timing Lots of evidence from eyeblink conditioning Inactivate cerebellum  no learning Belief that procedural memories are formed in the cerebellum

Answer 72

Cerebellum: monitors and adjusts motor behavior Activity changes constantly during the course of movement Cells tonically active and rest, but firing frequency increases during movement Responses influenced by relaxation/contraction of muscles, position of joints, direction of next movement

Answer 73

****Bottomline: always have problems making smooth, precisely directed movements***** Deficits can be quite specific. Site specific damage: Vestibulocerebellum: problems standing upright and controlling direction of gaze Nystagmus: eyes drift from target and then jump back to it with a corrective saccade Spinocerebellum: difficulty controlling walking movements, shuffling walk. Dysdiadochokinesia: difficulty performing rapid alternating movements Dysmetria: over- or under-reaching Intention tremors: due to disruption of the mechanism for detecting and correcting movement errors Cerebrocerebellum: impairments in highly skilled sequences of learned movements (speech, playing music) Cerebellar ataxia: Appendicular ataxia

Answer 74

sort of a hallmark symptom that something is wrong with your cerebellum; movements are jerky and imprecise instead of smooth and well-coordinated Why? Cerebellum is important for correcting errors to ongoing movements and adapt to changing circumstances. Movement errors are on same side of the body as damage Alcohol abuse  degeneration of the anterior portion of the cerebellar cortex (which affects movement of lower limbs) Results in staggering gait. No issues with arm or hand movement.

Answer 75

Birds have a very different shaped cerebellum (round vs spherical) Bird cerebellum greater in size and weight Cerebellums in different places Vermis is larger in birds Larger in birds that can fly than not Center of equilibrium while flying? Differences in sulci Cytoarchitecture very similar between the two Beak control?

Answer 76

Largest cerebellum of all mammals relative to brain | Trunk-eye coordination

Answer 77

``` Started walking late (at age 7) Walks unsteadily as an adult Slurred speech Mild intellectual impairment Has normal word comprehension and was “fully orientated” ```

Answer 78

Striatum (aka corpus striatum): caudate and putamen

Answer 79

* Nearly all regions of the cortex send direct projections to the striatum - Therefore, the cortex is the largest source of input - Mostly from association areas and the temporal, insular, and cingulate cortices - Collectively refer to these pathways as the CORTICOSTRIATAL PATHWAY

Answer 80

Most known for role in movement but functions not limited to movement

Answer 81

Striped because thin strips of gray matter that pass through the internal capsule to connect the caudate and dorsal putamen

Answer 82

Subthalamic nucleus: receives input from motor areas of the cerebral cortex, projects to the substantia nigra, and is reciprocally connected with the globus pallidus.

Answer 83

FALSE | Due to various Cell Neuro things (inward-rectifier potassium conductances), they rarely display spontaneous activity

Answer 84

*Thalamus- in general, talks back to regions of the cortex and serves as a modulator of cortical… decisions

Answer 85

GABA Globus pallidus and substantia nigra pars reticulata have lots of spontaneous activity Are constantly and tonically inhibiting their target structures because they release GABA

Answer 86

These nuclei are probably mostly involved in arousal and alertness.

Answer 87

Hypokinetic = decreased voluntary movement

Answer 88

Medium Spiny neurons increase firing rate before movement (even by several seconds) Putamen- discharge in anticipation of limb and trunk movements Caudate- discharge in anticipation of eye movement Some vary based on destination of movement Overall, suggests that Medium Spiny neurons encode the decision to move

Answer 89

caudate and putamen, Globus pallidus, substantia nigra pars reticulata

Answer 90

*Caudate --> substantia nigra pars reticulata --> superior colliculus (head and eye movements)

Answer 91

*Fastigial nucleus: medial; input from the vermis and from cerebellar afferents that carry vestibular, proximal somatosensory, auditory, and visual information Projects to the vestibular nuclei, thalamus, and the reticular formation.

Answer 92

Dentate nuclei Fastigial Nuclei Interposed Nuclei Vestibular nuclei: (outside the cerebellum in the medulla)

Answer 93

The vestibular nuclei receive input from the flocculonodular lobe (vestibulocerebellum) and from the vestibular labyrinth. They project to various motor nuclei and originate the vestibulospinal tracts.

Answer 94

Interposed nuclei

Answer 95

*Well developed in primates *Involved in the PLANNING AND TIMING of movements. Involved in the cognitive functions of the cerebellum. Includes the flocculus and nodulus

Answer 96

Projections are not direct They synapse on ipsilateral pontine nuclei Pontine nuclei receive input from a wide variety of sources, including most areas of cortex and the superior colliculus Axons from the pontine nuclei (transverse pontine fibers or pontocerebellar fibers) cross the midline and enter contralateral cerebellum via the middle cerebellar peduncle How we get info from one side of the cortex to the other side of the cerebellum

Answer 97

middle and inferior

Answer 98

*Originate exclusively in the INFERIOR OLIVE and make EXCITATORY PROJECTIONS onto the cerebellar nuclei and onto the Purkinje cells of the cerebellar cortex

Answer 99

*Receives modulatory inputs from the inferior olivary nucleus (inferior olive) Important for the learning and memory functions of the cerebellum Inferior olive gets input from a wide variety of structures including: the cortex, red nucleus, reticular formation, and spinal cord These olivo-cerebellar axons exit the inferior olive, cross the midline, and enter the contralateral cerebellum via the inferior cerebellar peduncle

Answer 100

The arrangement of Purkinje cells and parallel fibers resembles telephone lines running between telephone poles. Each parallel fiber makes contact with hundreds of Purkinje cells so the firing of each Purkinje cell can be influenced by thousands of mossy fibers.

Basal Ganglia and Cerebellum Flashcards

(125 cards)