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neuro final exam > Neuro Week 12 PT 2 (9-11) > Flashcards

Neuro Week 12 PT 2 (9-11) Flashcards

1
Q

Role of the pontocerebellum

A

Governance of voluntary movement and motor learning. It does not receive any projections from peripheral receptors

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2
Q

Afferent projections to the pontocerebellum originate in

A

Motor and association cortices of the cerebrum via cortico-pontocerebellar projections

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3
Q

Cortico-pontocerebellar projections descend from

A

Motor association cortex – likely supplementary & premotor cortex thru internal capsule & medial third of cerebral peduncle to end on neurons of pontine nuclei

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4
Q

Path of pontine nuclei axons

A

Decussate to enter thru contralateral middle cerebellar peduncle and rise to the cortex as Mossy fibers. Mossy fibers end on granule cells of lateral cerebellar cortex

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5
Q

Where does Mossy fiber collaterals end?

A

Neurons in the dentate nucleus.

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6
Q

Cerebellum uses information carried by the cortico-pontocerebellar pathway for

A

Movement initiation & execution

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7
Q

Lesions of corticopontine pathway or pontine nuclei result in

A

Contralateral deficits in arm & leg coordination

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8
Q

Lesion of the peduncle results in

A

Ipsilateral deficits in arm & leg coordination

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9
Q

Pontocerebellum cortex projects to

A

Dentate nuclei which in turn project out via the superior cerebellar peduncle to: Contralateral red nucleus Contralateral VL thalamus

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10
Q

Dentate projections to red nucleus end on

A

Parvocellular neurons which project to inferior olivary nucleus. Neurons then project back into the cerebellum providing regulatory feedback to the cerebellum

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11
Q

Dentate projections to VL nucleus of thalamus in turn project to

A

Motor & premotor cortex which produce Direct and indirect actions on UMN via corticospinal pathways & corticobulbar pathways

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12
Q

Functions of pontocerebellum

A

Movement initiation & voluntary execution of the movement - dentate projections to motor cortex via VL nucleus of thalamus are essential for the initial activation of corticospinal neurons at the beginning of a movement

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13
Q

Damage to the pontocerebellum produces

A

Delay of excitatory output from the motor cortex which results in a corresponding delay in muscle contraction. Activation of both agonist & antagonist muscle are delayed along with disruption of their reciprocal pattern of activation that accompanies many movements

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14
Q

Role of pontocerebellum

A

Timing of muscle activation (and inactivation), as well as influencing the duration of muscle contraction

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15
Q

T / F- Damage that involves only the cerebellar cortex rarely results in permanent motor deficits but damage to both cortex & nuclei or to nuclei alone results in a wide range of motor problems

A

True

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16
Q

Unilateral lesions of the cerebellum produce

A

Ipsilateral deficits.

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17
Q

Right dentate and interposed nuclei influence the

A

Left motor cortex and red nucleus- projections of the Left motor cortex & red nucleus project to the right side of the spinal cord So a lesion in the cerebellum on the right results in deficits on the right side of the body

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18
Q

Lesions of the lateral / pontocerebellum result in

A

Movement decomposition/ dyssynergia- deterioration of coordinated movement; deficit consists of the breakdown of movement into its individual component parts

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19
Q

Disorders of the cerebellum- HADDI

A
  • Hypotonia
  • Ataxia
  • Dysmetria
  • Dysdiadochokinesia
  • Intention tremor
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20
Q

Hypotonia

A

Decrease in muscle tone & deep tendon reflexes

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21
Q

Ataxia

A

uncoordinated limb movement which include:

Unsteady gait
Tendency to lean or fall to the side of the lesion

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22
Q

Dysmetria

A

Past pointing when pointing at stationary or moving objects

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23
Q

Intention tremor

A

Oscillation of limb as target is approached - occurs with performance of a voluntary movement

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24
Q

Dysdiadochokinesia

A

Awkward performance of rapid alternating movements & also manifested by inability to perform repeated rhythmic movements

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25
Q

Sensory & motor (cerebellar) ataxia

Sensory ataxia involves:

A

Disruption of proprioceptive afferents into the cerebellum.

Symptoms - Near-normal coordination when the movement in question is visually observed by the patient. However there is Marked worsening of coordination when the eyes are shut. Patient has a Positive Romberg sign & complains of problems walking in dark

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26
Q

Motor ataxia or cerebellar ataxia

A
  • Damage to the cerebellum itself.
  • Ataxia symptoms exist with or without vision
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27
Q

Cerebellar Influence on Visceromotor Functions

A
  • Cerebellar nuclei sends crossed projection to the hypothalamus (cerebellohypothalamic fibers) via the superior cerebellar peduncle
  • Through these reciprocal connections, the cerebellum may receive visceral input and influence neurons that control visceral functions
28
Q

Visceral deficits are seen with cerebellar damage but often go unreported unless specifically tested for because they are relatively minor compared to somatomotor deficits. These deficits include:

A
  • Decrease in heart rate and blood pressure
  • Changes in vascular resistance
  • Changes in pupil diameter
29
Q

The effects of cerebellar dysfunction are dependent on the type of behavior being learned. The cerebellum appears to be involved in different aspects of the learning process of motor behaviors including:

A

Acquisition, consolidation, and memory storage of movement patterns

30
Q

The cerebellum plays a very critical role in the learning of relatively simple reflexive motor behaviors including:

A
  • Adaptation of the vestibulo-ocular reflex and the
  • Classical (Pavlovian) conditioning of reflexes evoked by aversive stimuli
  • Eye-blink
  • Withdrawal reflexes
31
Q

Cerebellum plays an even more important role in the Learning of voluntary, complex motor skills- New motor skills can be learned with cerebellar dysfunction but Cerebellar dysfunction result in:

A
  • Decrease in the quality & consistency of the learned behaviors
  • Slowing of the rate of motor learning
32
Q

The cerebellum is Involved in the acquisition process,

A

Imaging studies show that specific cerebellar regions activated during the learning of novel movements. Cerebellar nuclei active when first learning to perform the task correctly and consistently on successive trials but the cerebellum is Less active in an already learned movement or one where skill is already demonstrated

33
Q

The cerebellum has been implicated in Memory storage of motor tasks. There is little evidence of storage of learned voluntary, complex motor skills as patients with cerebellar damage can often reproduce already learned skills. That form of storage is likely in the supplementary motor cortex.

A

However there is evidence of long term suppression of learned adaptation of reflexes (such as VOR) with cerebellar damage so Either cerebellum is either a storage site Or it is necessary for activation of storage

34
Q

Summary of the Cerebellar Components: Connections & Roles

Archicerebellum (vestibulocerebellum)

A
  • Involves midline structures such as the flocculonodular lobe.
  • Connections are thru fastigial nucleus.
  • Highly interconnected with vestibular & reticular nuclei
  • Roles in VOR, posture, balance & equilibrium
35
Q

Summary of the Cerebellar Components: Connections & Roles

Paleocerebellum (spinocerebellum)

A
  • Located in the Intermediate cerbellum, that is the vermis & paravermal areas.
  • Connections are thru both the fastigial & interposed (globose & emboliform) nuclei
  • Highly Interconnected with spinal cord and brainstem.
  • Involved in the Coordination of reciprocal contraction of agonists and antagonists in motor activities
36
Q

Summary of the Cerebellar Components: Connections & Roles

The Neocerebellum (Pontocerebellum)

A
  • Most lateral component and includes the lateral cerebral hemispheres.
  • Associated with Dentate Nucleus.
  • Has Substantial inputs from cerebral cortex and outputs to motor cortex via VL thalamus and circuit back into cerebellum via inferior olivary nucleus
  • Functions in coordination of sequential motor activities initiated by cerebral cortex
37
Q

Functions of the cerebellum include:

A
  • Anticipatory programming of agonist and antagonist to maintain posture & balance during rapid movements via outputs to vestibular nuclei & reticular formation
  • Comparison of plan of movement (input from cerebral cortex) with the actual position of the limbs (feedback from spinocerebellar pathways) with correction if errors via outputs to cerebral cortex and red nucleus
38
Q

The cerebellum also Functions in:

A
  • Movement precision
  • Preprogramming of ballistic movements
  • Planning and timing of complex sequential movements
  • Integration of visual & proprioceptive information to execute planned movements
  • Consolidation of motor memory but not storage
  • Possible coordination of some visceral actions
  • Possible role in emotional & cognitive function
39
Q

Motor control

A

Ability to regulate or direct the mechanisms essential to movement

40
Q

Motor planning

A

Preliminary organization prior to movement

41
Q

Programming

A

Specifications that allow movement to progress

42
Q

Motor Cortical Areas – Frontal areas

A
  • Primary motor
  • Supplementary motor
  • Lateral pre-motor
43
Q

Motor cortical areas- Parietal areas

A
  • Posterior parietal area- limbic areas
  • Anterior & posterior cingulate areas
44
Q

Frontal Cortex comprised of 3 areas

A
  • Primary motor cortex (PMC) – precentral gyrus
  • Supplementary motor cortex – most superior and medial aspects of superior frontal gyrus
  • Pre-motor cortex - Lateral frontal cortex – just rostal to PMC
45
Q

Primary motor cortex

A
  • located along the Precental gyrus - Brodmann’s area 4.
  • Has a somatotopic organization – homunculus with LE – dorsomedial and UE & face– ventro-lateral.
  • This pattern is often called a “Fractured somatotopy” with Overlapping regions & scattered distribution of motor neurons which innervate specific muscles.
46
Q

Fractured homunculus illustrated by:

A

Overlap and broad distribution of the Cortical motor neurons (CM) to specific muscles. Intrinsic thumb muscles example, CM neurons for the thumb instrinsic muscles are over all 4 regions. There is overlap with cortical motor neurons innervating the finger muscles in one area but in other areas thumb muscle cortical motor neurons overlap with wrist, orofacial and even trunk cortical motor neurons

47
Q

Primary motor cortex

A
  • Debate as to role in movement
  • Lowest level of cortical hierarchy
  • Encode specific muscle kinetic features – amount of force for specific movement
  • Kinematic features – speed, direction & spatial path
48
Q

The Supplementary Motor Cortex

A
  • Located along the superior and Medial aspect of superior frontal gyrus.
  • Also has a Somatotopic representation face, UE & LE arranged in a rostral-caudal orientation.
  • Stimulation of this area elicits movements but in complex synergy patterns
  • Active well before movements occur – suggesting a site for motor planning
49
Q

Damage to SMC causes

A

Problem in bimanual tasks, motor memory & learning

50
Q

Premotor Cortex

A
  • Just rostral to primary motor cortex
  • Has a Rough somatotopic organization that parallels the primary motor cortex.
  • Related to synergy patterns when stimulated.
  • kinematic features of targeting movements here rather than 1° motor cortex
51
Q

Parietal Cortex contains Posterior Parietal Cortex (PPC) which is critical for providing

A

Spatial information for goal-directed movement and provides the knowledge of Spatial relationships of the environment and how these impact the movement as it takes place

52
Q

Posterior Parietal Cortex

A

Provides the Critical spatial information for goal-directed movement such as the relative Orientation of the body toward the goal directed objects and a determination of the Relative shapes & sizes & orientation of objects within the environment

53
Q

Limbic Cortex particularly the anterior cingulate gyrus along with the parietal lobe contributes to

A

1/3 of pyramidal tract neurons. Somatotopic map of face to feet in rostral-caudal topography simlar to what is seen in the supplementary motor cortex

54
Q

Limbic cortex Cingulospinal projections terminate in the

A

Intermediate gray, influencing LMNs via interneurons. The anterior cingulate cortex receives widespread input from amygdala and non-motor areas of cingulate gyrus

55
Q

Limbic cortex Anterior cingulate gyrus provides

A

Motivational and reward (goal of performance) information

56
Q

Cortical Connections related to motor function input to the primary motor cortex comes from

A

1° somatosensory areas analogous to the regions of 1° motor cortex (particularly hand region) There is also input into the 1° motor cortex from pre-motor cortex, SMA & CMA. Of particular interest is the Dorsolateral prefrontal cortex (DLPFC) input into 1° motor cortex and into SMA & CMA.

57
Q

Function of the Dorsolateral prefrontal cortex input provides for

A

Short term memory for action related sensory information, for the Preparatory motor set and to allow for the Inhibition of motor response to distracting stimuli.

There are also prominent Posterior parietal input to 1° motor cortex

58
Q

Sub-cortical Connections -Basal Nuclei Loop

A
  • Supplementary motor cortex projects to the striatum.
  • Direct and indireect pathways within the basal nuclei and the incorporation of the substantia nigra with the normal outputs of GPi/SNr to VL/VA thalamus then onto 1° motor cortex
59
Q

Sub cortical connections- Cerebellar Loop

A
  • 1° motor cortex & pre-motor cortex to pontine & inferior olivary nuclei.
  • These pontocerebellar and olivocerebellar fibers have Input to cerebellar deep nuclei & cortex.
  • Deep nuclei then have output to the VL thalamus & back to 1° motor cortex
60
Q

Perceptual action system (PAS)

A

Purposeful movement does not occur in isolation from the sensory perceptual experience of the environment it requires input from the environment to correctly execute motor action.

61
Q

Haptic sensing

A

Generation of sensory input from deliberate motor action. e.g. exploration of an object by the hand and the Integration of cutaneous and propioceptive information into motor commands.

Haptic sensing does require working memory which is provided by action of the Dorsolateral prefrontal cortex & posterior parietal cortex

62
Q

Eye movement - Visual Saccades

A

Ballistic voluntary conjugate eye movements used to capture a visual image onto the fovea of the retina. Used in reading and visual scanning.

Motor programs for saccades reside in reticular formation of midbrain & pons – central pattern generator for conjugate eye movement.

63
Q

Brainstem region for eye movement is controlled by the

A

Superior colliculus (SC) which coordinates movements of the eyes via tectobulbar projections (to reticular formation central pattern generator neurons) and head via the tectospinal tract (to cervical spinal cord)

64
Q

Location of Frontal eye field

A

Middle frontal gyrus rostral to premotor cortex. It Generates contralateral horizontal conjugate eye movement and has Projections to superior colliculus and then to reticular formation

65
Q

Supplementary eye field in SMA projections

A

Brainstem and to frontal eye fields.

There is also a Parietal eye field in parietal lobe which is just inferior lateral to the posterior parietal area which also Projects to brainstem and to frontal eye field. Roles organizing function of the supplementary eye fields and a spatial coordination function of the parietal eye fields

66
Q

Performance of an instructed motion causes activation of

A

Auditory cortex and Wernicke’s area for the hearing and Interpretation of language command.

Activation of parietal eye fields and posterior parietal cortex - for placing this command within the movement space – spatial environment and coordination of eye movement to that site of placement

Organization of motion by Premotor cortex & also supplementary motor cortex

Primary motor cortex - commands of spinal motor neurons to perform the movement

Cerebellar efferent copy & proprioceptive feedback to cerebellum -necessary for all movement.

neuro final exam (10 decks)

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