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4 Neuroscience > L6 Cerebellum and Basal Ganglia > Flashcards

L6 Cerebellum and Basal Ganglia Flashcards

1
Q

What is the role of the basal ganglia?

A

regulate the activity of the upper motor neurons DIRECTLY. This INDIRECTLY influences lower motor neurons

looks at a motor task and decides if that plan should be reinforced or inhibited

helps select the most appropriate motor action

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2
Q

Striatum is responsible for…

A

input
receives input related to movement, plays a role in coordinating motor activities

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3
Q

Pallidum is responsible for

A

output
processes movement signals and contributes to motor control

output goes through VA/VL thalamus back to cortex

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4
Q

Substantia Nigra Pars Compacta and Subthalamic Nucleus

A

provide input to striatum and pallidum, influencing their functions

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5
Q

Medium spiny neurons

A

found in the striatum
play a crucial role in processing of neural signals related to motor and cognitive functions

GABA neurons, inhibitory influence

modulated by dopamine from the substantia nigra, can also receive serotonin from raphe nuceli

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6
Q

Excitation of MSP

A

comes from the cortex (like frontal and parietal lobes)

these axons form the coticostriatal pathways and carry glutamate to the MSPs

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7
Q

When do medium spiny neurons become active?

A
  1. Firing is associated with occurrence of movement
  2. Can precede the movement, so anticipatory discharges
  3. May help with the decision to move, rather than direction or amplitude
  4. Increase firing at termination
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8
Q

What are the inputs to the basal ganglia?

A

Parietal and Frontal Cortex –> go to the striatum

Substantia nigra pars compacta –> go to striatum, using dopamine

(also intralaminar nuclei use glutamate to striatum)

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9
Q

Striatum is made up of

A

caudate
putamen
(nucelus accumbens)

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10
Q

Outputs of basal ganglia

A
  1. Substantia nigra pars reticulata –> superior colliculus (head and neck)
  2. Globus pallidus internal –> VA/VL –> frontal cortex (rest of body)
  3. Globus pallidus external –> subtahalmic nuclei –> GPi –> Va’VL –> frontal cortex
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11
Q

Example: Eyes fixating on visual target

A

Tonic inhibition from SnPr
Medium spiny neurons inhibit SnPr via GABA, this disinhibits UMNs of superior colliculus and allows saccades to happen

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12
Q

Direct pathway

A

Provides means for basal ganglia to facilitate the initiation of voluntary movement

Substantia nigra pars compact –> (+) caudate putamen –> (-) globus pallidus –> (-) VA/VL –> (+) frontal cortex

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13
Q

Indirect pathway

A

modulates the disinhibitory actions of the direct pathway

Substantia nigra pars compact –> (-) caudate putamen –> (-) globus pallidus external –> (-) subthalamic nucleus –> (+) Globus pallidus internal –> (-) VA/VL –> (+) frontal cortex

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14
Q

Indirect and direct pathways faciliatate

A

selection of a motor program and suppress competing motor programs that could interfere with the expression of sensory driven or goal oriented behavior

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15
Q

Dopamine Modulates Basal Ganglia

A

SnPc contains dopamine

dopamine interacts with the medium spiny neurons, the effect is dependent on what kind of receptor the dopamine goes to

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16
Q

D1 Receptors

A

enhance the excitatory input from the cortex

enhances the direct pathway

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17
Q

D2 Receptors

A

suppresses the excitation from the cortex

involved with the indirect pathway, helps to decrease the excitation that occurs on the frontal cortex

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18
Q

Parkinson’s disease

A

second most common degenerative disease of NS

causes a breakdown of the substantia nigra pars compacta

lack of dopamine inputs, making it more difficult to generate the transient inhibition from the striatum

causes the direct pathway to increase or sustain the inhibition to the globus pallidus, making thalamic exicitation of the motor cortex less likely

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19
Q

Huntington’s Disease

A

The striatum size is dramatically reduced

the projection from the striatum to the globus pallidus external is dimished

increases the tonic inhibition from the globus pallidus (indirect pathway), making the inhibitory pathway less effective, causing increased excitation of the cortex

unwanted motor activity

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20
Q

Prefrontal loops of BG

A

may regulate the initiation and termination of cognitive processes like planning, short term memory, and attention

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21
Q

Limbic loop of BG

A

may regulate emotional and motivated behavior, as well as the transitions from one state to another

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22
Q

Role of the cerebellum

A

Critical for prediction and improvement

Does not act directly on LMNs, but regulate UMNs

Copy of the motor command goes to the cerebeullum, and then it can send back the expected sensory feedback

also communicates with the inferior olives, which send back errors to the cerebellum

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23
Q

Cerebrocerebellum

A

receives input from much of the cortex

regulation of highly skilled movements

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24
Q

Spinocerebellum

A

receives input directly from the SC

concerned with movements of proximal muscles and some eye movements

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25
Q

Vestibulocerebellum

A

flocculus and nodules
receives input from the vestibular nuclei, does VOR and movements that help maintain posture/equilibrium

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26
Q

Cortical Projections to the Cerebellum

A

Most comes from the cortex –> inspilateral pontine nuclei –> contralateral cerebellum via middle cerebellar peduncle

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27
Q

Sensory Projections to Cerebellum

A
  1. Vestibular axons from pons and medulla, which go to the vestibulocerebellum
  2. Clarkes nucleus and ex. cunneate nucleus carry proprioceptive info to the spinocerebellum
  3. Face info comes from trigeminal nucleus, to spinocerebellum
28
Q

Entire cerebellum receives…

A

modulatory inputs from the inferior olivary nucleus

plays an important role in learning and memory functions

29
Q

Outputs from the cerebellum

A
  1. Cerebellar cortex –> DCN –> UMNs
  2. Dentate nucleus –> premotor and association cortex, doing planning of movements
  3. Red nucleus to inferior olive, helps to provide feedback on major inputs
30
Q

Cerebrocerebellum nucli and peduncles

A

Dentate nucleus
Superior and middle peduncle

31
Q

Spinocerebellum nuclei and peduncle

A

Interposed nuceli
Inferior peduncle

32
Q

Vestibulocerebellum nuclei and peduncle

A

Fastigial nucleus
Inferior peduncle

33
Q

Ultimate destination of inputs (afferent pathways)

A

Purkinje cell

34
Q

The largest of the afferent pathways

A

arises in cerebral cortex and terminates in the pontine nuclei of basal pons. Then, the pons will project to the cerebellum

35
Q

Mossy fibers

A

axons that are coming from the pontine nuclei to provide input to the cerebellum

they will send fibers that synapse in the deep cerebellar nuclei and granule cells

36
Q

Parallel Fibers

A

come from granule cells
ascend the cerebellar cortex, will bifurcate to form T shaped branches

they will then form excitatory synapses with purkinje cells

37
Q

Purkinje Cell

A

their orientation allows for them to receive input from lots of parallel fiber

also receives input from climbing fibers, which modulate their connection to parallel fibers

38
Q

Purkinje Cells and output

A

project to deep cerebellar nuclei

they use GABA, so the output is inhibitory, manage the climbing and mossy fiber’s outputs onto the DCN

39
Q

Purkinje Cells and DCN

A

recognize potential errors by comparing patterns of activity

DCN will send the corrective signal to the UMNs

40
Q

Hallmark of individuals with cerebellar damage

A

difficulty producing smooth, well-coordinated, multi-jointed movements

41
Q

Movement disorders associated with the cerebellum

A

Cerebellar ataxia
Nystagmus
Dysdiadochokinesia
Dysmetria
Intention tremors

42
Q

Dysdiadochokinesia

A

difficulty with rapid alternating movements

43
Q

Dysmetria

A

over or underreaching

44
Q

Attention

A

allocation of neural resources to the analysis of particular information at the expense of resources that might have been allocated to other concurrent info

Cocktail party effect–listener can attend to one voice in a noisy conversation and tune out other signals

45
Q

Endogenous attention

A

consciously direct attention to a particular aspect of the environment

46
Q

Exogenous attention

A

involuntary refers to the situation in which an unexpected noise, flash of light, movement, and or other salient stimulus causes a shift in focus

47
Q

Hemispatial neglect

A

right parietal, superior temporal, right frontal brain damage

leads to difficulty attending to the left side of visual space or left side of objects

R impact –> influences both hemispheres
L impact –> impacts the right

48
Q

Declarative memory

A

storage and retrieval of material that is available to consciousness and can be expressed by language

daily episodes, words/meanings, history

EX: ability to remember a phone number, words to a song, or past event

49
Q

Nondeclarative memory

A

referred to as procedural memory

Motor skills, associations, priming cues, puzzle solving skills

not available to consciousness, involve skills and associations that are acquired and retrieved at an unconscious level

EX: playing a piano, how to shoot a basketball

50
Q

Immediate memory

A

ability of the brain to hold onto ongoing experience for a second or so

51
Q

Short term memory

A

ability to hold and manipulate info in the mind for seconds to minutes while it is being used to achieve a particular goal (working memory)

searching for an object

52
Q

Long-term memory

A

retaining information in a more permanent form of storage for days, weeks, lifetime.

immediate and short term can enter into long term by conscious or unconcious practice

53
Q

Consolidation

A

the progressive stabilization of memories that follows the initial encoding of memory traces

Involves changes in gene expression, protein synthesis, and other mechanisms of synaptic plasticity that allow the persistence of memories at the cellular level

54
Q

Priming

A

the change in the processing of a stimulus due to a previous encounter with the same or a related stimulus with or without conscious awareness of the original encounter

not very reliable because it can be influenced by associations and biases

importance = shows info previously presented will always be influential, even without awareness

55
Q

Capacity of memory…

A

depends on what the info in question means to the individual and how readily it can be associated with info that is already stored

motivation also helps

56
Q

Conditioned learning

A

novel response that is gradually elicited by repeatedly pairing a novel stimulus with the stimulus that usually produces the response

classical and operant

57
Q

Classical conditioning

A

Pavlovs dog

innate reflex is modified by associating its normal trigger with an unrealted stimulus, the unrelated stimulus eventually triggers the original response

58
Q

Operant conditioning

A

learning a behavior is strengthened or weakened by the consequences that follow it

learned behaviors can also disapper if the reward is not given

59
Q

Forgetting

A

we forget information to help us to be not overburdened by information

60
Q

Anterograde amnesia

A

inability to establish new memories following neurologic injury

61
Q

Retrograde amnesia

A

difficulty retrieving memories established prior to the neurologic injury

62
Q

Declarative Memories and Hippocampus

A

we use the hippocampus to encode and initiate the consolidation of memories of events, creating long term memories

rats swimming–> they were able to find the submerged platform after learning the visual stimuli

63
Q

Long Term Storage of Declarative

A

transferring information from short-term memory to long-term memory, known as memory consolidation, involves the hippocampus

as memories become more stable and well-established, they are gradually distributed to other parts of the neocortex for long-term storage. This process is often referred to as system-level consolidation.

64
Q

Acquisition and storage of declarative information

A

Short term memory –> hippocampus

Long Term –> cortical sites including Wernickes, temporal cortex

65
Q

Acquisition and storage of non-declarative information

A

Short-term memory: sites unknown

Long Term: cerebellum, basal ganglia, premotor cortex, motor behavior sites

66
Q

Memory and Aging

A

Average weight of normal human brain decreases from early adulthood onward

synapse # decreases in cerebral cortex

networks of connection representing memories gradually deteriorate

4 Neuroscience (9 decks)

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