Neurophysiology Part Iif

Front 1

What are the 3 functional regions of the cerebellum?

Back 1

Vestibulocerebellum (flocculonodular lobe)
Spinocerebellum (vermis and intermediate hemispheres)
Cerebrocerebellum (lateral hemispheres)

Front 2

What are the major inputs to the vestibulocerebellum?

Back 2

Primary vestibular nuclei

Front 3

What is the function of the vestibulocerebellum?

Back 3

controls balance and eye movements

Front 4

What are the major inputs to the spinocerebellum?

Back 4

The vermis receives visual, auditory, vestibular, and somatic sensory input from the head and proximal body.
The intermediate hemispheres receive somatosensory input from the limbs.

Front 5

What regions of the nervous system are influenced by output from the spinocerebellum?

Back 5

The vermis projects to cortical and brainstem regions that give rise to the medial descending systems (via the fastigial nucleus). The intermediate hemispheres project to the lateral corticospinal and rubrospinal systems (via the interposed nucleus).

Front 6

What is the function of the spinocerebellum?

Back 6

The vermis helps govern posture, locomotion, and gaze.
The intermediate hemispheres control the more distal muscles of the limbs and digits.

Front 7

What are the major inputs to the cerebrocerebellum?

Back 7

cerebral cortex

Front 8

Which regions of the nervous system are influenced by output from the cerebrocerebellum?

Back 8

motor
premotor
prefrontal cortices (via the dentate nucleus)

Front 9

What are the functions of the cerebrocerebellum?

Back 9

planning and mental rehearsal of complex motor actions

Front 10

What are the three layers of the cerebellar cortex?

Back 10

Molecular layer (outermost)
Purkinje cell layer
Granular layer (innermost)

Front 11

What is the output neuron of the cerebellum? What neurotransmitter does it release?

Back 11

Purkinje cells, which release GABA

Front 12

Describe one scientific study that indicates that the cerebellum also has cognitive functions that are independent of motor execution.

Back 12

Activity in the dentate nucleus is significantly greater when the subject is mentally active during movement (solving a pegboard puzzle as compared to simply moving pegs in the pegboard). Cognitive activity can also be isolated from sensory stimulation or movement.

Front 13

"The type of motor learning with which the cerebellum is concerned is..."

Back 13

...trial and error practice

Front 14

List the three categories of abnormality that result from damage or disease of the cerebellum.

Back 14

Hypotonia
Ataxia
Intention tremor

Front 15

What is hypotonia?

Back 15

Diminished resistance to passive limb displacements

Front 16

What is ataxia?

Back 16

lack of coordination

Front 17

What is intention tremor?

Back 17

Tremor that is most marked at the end of a movement when the patient attempts to stop by using antagonist muscles.

Front 18

What functional impairment is present when there is damage to the vermis and fastigial nuclei?

Back 18

Disturbances principally in control of the axial and trunk muscles during antigravity posture

Front 19

What function impairment is present when there is damage to the anterior lobes of the cerebellum? What causes such damage?

Back 19

Alcohol or thiamine deficiency.
Ataxia and tremor of the legs and trunk in standing and walking, but not in the arms or head

Front 20

What functional impairment is present when there is damage to the intermediate cerebellum and interposed nuclei?

Back 20

action tremor of the limbs

Front 21

What functional impairment is present when there is damage to the lateral cerebellar hemispheres?

Back 21

delays in initiating movement and decomposition of multi-joint movements
inability to combine thumb and index finger in a precise pinch

Front 22

What is dysmetria?

Back 22

errors in the range of movement

Front 23

What is dysdiadochokinesia?

Back 23

the patient cannot sustain a regular rhythm or produce an even amount of force when performing rapid alternating movements

Front 24

What is decomposition of movement?

Back 24

errors in timing of components of complex, multijoint movements

Front 25

What is action or intention tremor?

Back 25

series of erroneous corrections in range of movement due to failure of adaptive control

Front 26

What is one difference in the input/output connections of the basal ganglia and other components of the motor system?

Back 26

The basal ganglia have no output to the spinal cord

Front 27

Describe the basic loop between the basal ganglia and the motor cortex.

Back 27

The cortices (primary motor, premotor, prefrontal) project to the basal ganglia and they project back to the cortices via the thalamus

Front 28

Describe the 3 characteristic types of motor disturbance caused by damage/disease of the basal ganglia.

Back 28

1) Tremor and involuntary movements
2) Changes in posture and muscle tone
3) Poverty and slowness of movements without paralysis

Front 29

What region of the basal ganglia is the major recipient of inputs?

Back 29

Striatum (caudate nucleus, putamen, ventral striatum - including nucleus accumbens)

Front 30

What two nuclei give rise to the major output projections of the basal ganglia?

Back 30

Globus pallidus
Substantia nigra

Front 31

What neurotransmitter is released by the output nuclei of the basal ganglia?

Back 31

GABA

Front 32

What neurotransmitter is released by the compact zone of the substantia nigra?

Back 32

Dopamine

Front 33

What neurotransmitter is released by the neurons of the subthalamic nucleus?

Back 33

Glutamate (the only excitatory projections in the basal ganglia)

Front 34

What is the effect of the tonic activity of neurons in the internal pallidal segment and substantia nigra pars compacta on their target neurons in the thalamus and brainstem?

Back 34

Inhibitory

Front 35

What is the effect of increased activity of the direct pathway through the basal ganglia on neurons in the thalamus and, ultimately, the cortex?

Back 35

Activation (through disinhibition)

Front 36

Does increased activity of the direct pathway facilitate or inhibit movement?

Back 36

Facilitates

Front 37

What is the effect of increased activity of the indirect pathway through the basal ganglia on the thalamocortical activity?

Back 37

Inhibition

Front 38

Does increased activity of the indirect pathway facilitate or inhibit movement?

Back 38

Inhibits

Front 39

What is the effect of the dopaminergic input from the substantia nigra pars compacta to the direct and indirect pathways on thalmocortical activity and on movement?

Back 39

Dopaminergic input to the direct pathway facilitates transmission, and dopaminergic input to the indirect pathway reduces transmission. Both of these effects results in disinhibition of thalamocortical activity and facilitates movements initiated in the cortex.

Front 40

What is the sequence of activation of neurons in the basal ganglia and the motor cortex at the onset of rapid, stimulus-triggered limb movement?

Back 40

motor cortex is first, then the basal ganglia

Front 41

What are the characteristics of hypokinetic disorder? What is one example of this disorder?

Back 41

Impaired initation of movement
Reduced amplitude and velocity of movements
Accompanied by muscle rigidity and tremor
Ex: Parkinson's disease

Front 42

What are the characteristics of hyperkinetic disorder? Give two examples of this disorder.

Back 42

Excessive motor activity
Involuntary movements
Decreased muscle tone
Ex: Huntington's disease and Hemiballismus

Front 43

What is akinesia?

Back 43

Impaired initiation of movement

Front 44

What is bradykinesia?

Back 44

reduced amplitude and velocity of voluntary movement

Front 45

What is dyskinesia?

Back 45

Involuntary movements

Front 46

What is athetosis?

Back 46

slow, writhing movements of the extremities

Front 47

What is chorea?

Back 47

jerky, random movements of the limbs and the orofacial structures

Front 48

What is ballism?

Back 48

Violent, large-amplitude, proximal limb movements

Front 49

What is dystonia?

Back 49

Abnormal postures and slower movements with underlying co-contraction of agonist and antagonist muscles

Front 50

"Some movement disorders (such as Parkinson's disease or Huntington's disease) result from..."

Back 50

...imbalances between the direct and indirect pathways in the basal ganglia

Front 51

What are the characteristic signs of Parkinson's disease?

Back 51

Paucity of spontaneous movement
Akinesia
Bradykinesia
Increased muscle tone
Characteristic tremor (4-5 Hz) at rest

Front 52

What neurotransmitter is reduced in patients with Parkinson's disease?

Back 52

Dopamine

Front 53

What is the location of the lesion to the basal ganglia that causes Parkinson's disease?

Back 53

Loss of dopaminergic projections from the pars compact of the substantia nigra to the striatum (nigrostriatal pathway)

Front 54

What are the overall effects of loss of dopaminergic input to the striatum on activity of the GABAergic neurons of the basal ganglia output nuclei?

Back 54

Increased

Front 55

What are the overall effects of loss of dopaminergic input to the striatum on thalamocortical activity?

Back 55

Inhibition

Front 56

What are the overall effects of loss of dopaminergic input to the striatum on movement?

Back 56

inhibition

Front 57

What is the MPTP model of Parkinsonism?

Back 57

MPTP treatment of primates causes Parkinsonism. Experiments show increased activity along the indirect pathway that is reversed with administration of dopamine receptor agonists.

Front 58

What is a common pharmacological treatment for Parkinsonism? What are the limitations of this therapy?

Back 58

Systemic administration of L-DOPA, but this treatment is only effective for about 5 years

Front 59

What are the two sites of surgical intervention in Parkinson's disease? What effects does this surgery have?

Back 59

Subthalamic nucleus and the internal globus pallidus
They ameliorate the cardinal parkinsonian motor signs

Front 60

What portion of the basal ganglia is affected in hemiballism?

Back 60

subthalamic nucleus

Front 61

What portion of the basal ganglia is affected in chorea?

Back 61

putamen (indirect pathway)

Front 62

What is the overall effect of lesions to the subthalamic nucleus and ptuamen on activity of the GABAergic neurons of the basal ganglia output nuclei?

Back 62

decreased

Front 63

What are the overall effects of lesions to the subthalamic nucleus and putamen on thalamocortical activity?

Back 63

activation

Front 64

What are the overall effects of lesions to the subthalamic nucleus and putamen on movement?

Back 64

facilitation

Front 65

What causes Huntington's disease in terms of brain structures?

Back 65

It involves neuron death in the caudate nucleus, specifically, neurons that give rise to the indirect pathway. Therefore, inhibition of neurons in the external pallidum is reduced, causing excessive discharge of these neurons and inhibition of the subthalamic nucleus.

Front 66

What do the dementia and depression associated with Huntington's disease imply about the role of the basal ganglia in other (non-motor) functions of the brain?

Back 66

The basal ganglia have a role in cognition, mood and non-motor behavior.

Front 67

What is the hypothetical relationship between glutamate excitotoxicity and Huntington's disease?

Back 67

Glutamate excitotoxicity models cause similar neuronal death patterns as those seen in Huntington's.

Front 68

Briefly describe the location of the ascending arousal system.

Back 68

From the rostral pons through the thalamus and hypothalmus to diffusely innervate the cortex.

Front 69

What is consciousness?

Back 69

The property of being aware of oneself and one's place in the environment.

Front 70

What is the clinical definition of consciousness?

Back 70

The ability to orient appropriately to stimuli is dependent upon the summate activity of the two cerebral hemispheres.

Front 71

What is the implication of a generalized impairment of consciousness?

Back 71

Diffuse dysfunction to both cerebral hemispheres.

Front 72

What is coma?

Back 72

A state of profound un-arousability; the thalamus is not in transmission mode (the state in which the resting membrane potential of the thalamic relay neurons is near the firing threshold) and the pattern of the EEG is synchronized (similar to deep sleep).

Front 73

What causes coma?

Back 73

Lesions of the ascending arousal system or bilateral damage to the cerebral hemispheres

Front 74

What are three conditions that can result in coma?

Back 74

Bilateral subdural hematomas
Multiple brain tumors
Prolonged diffused metabolic process (electrolyte imabalance or lack of oxygen)

Front 75

What is the difference between hypoxia and ischemia?

Back 75

Hypoxia is inadequate oxygenation, while ischemia is insufficient blood flow.

Front 76

What neuronal damage results in a persistent vegetative state?

Back 76

Severe damage to the large pyramidal neurons in the hippocampal formation and cerebral cortex (particularly in laminae III and V)

Front 77

Distinguish persistent vegetative state from brain death.

Back 77

Persistent vegetative state is characterized by a wakeful appearance. Patients may eat food placed in their mouth, smile, cry, and fixate on objects in the environment, but their actions have no cognitive content and bear little relationship to events that surround them.
Brain death is the cessation of all brain activity. They may have spinal level motor responses, but no purposeful movements, no brainstem reflexes, and no respiratory movements.

Front 78

Describe what is meant by "field potential".

Back 78

Synchronized activity of a large number of neurons

Front 79

What does the EEG represent?

Back 79

A set of field potentials as recorded by multiple electrodes on the surface of the scalp.

Front 80

What is the standard placement of EEG electrodes on the surface of the scalp?

Back 80

16 electrodes placed in two crescent shapes

Front 81

What is the location of synapses whose activity is detected by the EEG electrodes?

Back 81

Synapses on apical dendrites of pyramidal neurons close to the EEG electrode

Front 82

Compare the amplitude of the spike of a field potential recorded by the EEG with that of a spike recorded intracellularly from an individual neuron.

Back 82

The amplitude of the spike of a field potential recorded intracellularly from an individual neuron is much greater than that recorded by an EEG.

Front 83

What is the range of frequencies and spike amplitudes recorded in a typical EEG?

Back 83

The EEG records spikes that range from 1-30 Hz, and amplitudes ranging from 20-100 microvolts

Front 84

What are the four types of waveform observed in a normal EEG? Give the spike frequency and state of consciousness for each as well.

Back 84

Alpha (8-13 Hz, relaxed wakefulness)
Beta (13-30 Hz, alert wakefulness)
Delta (.5-4 Hz, drowsiness, early slow-wave sleep)
Theta (4-7 Hz, drowsiness, early slow-wave sleep)

Front 85

What is the incidence of epilepsy in the US?

Back 85

3% of all people under the age of 80

Front 86

Which individuals are most likely to have epilepsy?

Back 86

young children and the elderly

Front 87

What are the two general categories of siezure?

Back 87

Partial and Generalized

Front 88

What is tonic phase?

Back 88

rigidly extending all extremities; it is seen in both partial and generalized seizures

Front 89

What is clonic phase?

Back 89

jerks in all extremities; it is seen in both partial and generalized seizures

Front 90

What is tonic-clonic phase?

Back 90

Also called "grand mal seizure"; consists of 30 seconds of tonic phase and 1-2 minutes of clonic phase; it is seen in both partial and generalized seizures

Front 91

What is aura?

Back 91

symptoms preceding the onset of a partial seizure; includes abnormal sensations such as sense of fear, a rising feeling in the abdomen, or a specific odor; due to electrical activity originated from the seizure focus and thus represents the earliest manifestations of a partial seizures; it's only found in partial seizures

Front 92

What is an absence seizure?

Back 92

Also called a petit mal seizure; prototypic nonconvulsive generalized seizure is the typical absence seizure found in children; they begin abruptly, usually last less than 10s, are associated with cessation of all motor activity and result in loss of consciousness. There is no aura or postictal phase, no tonic-clonic movements. It is only found in generalized seizures.

Front 93

What is the minimum criterion for a diagnosis of epilepsy?

Back 93

recurrent, unprovoked seizures

Front 94

What is status epilepticus?

Back 94

repeated generalized seizures without regaining full consciousness between seizures

Front 95

What is the category of epilepsy that is most common in adult-onset epilepsy? What are the four causes of it?

Back 95

Symptomatic, localization-related epilepsy
Trauma, stroke, tumors, infection

Front 96

Compare the amplitude of EEG spikes during epileptic activity with the amplitude of the spikes during normal EEG activity.

Back 96

The amplitude of EEG spikes during epileptic activity is greater than the amplitude of spikes during normal EEG activity.