Lecture 4 - Basal Ganglia and Spinal Cord

Question 1

The basal ganglia is divided into two regions: the ________ and the _________ _______

Answer 1

Striatum & Lenticular Nucleus

Question 2

The striatum of the basal ganglia consists of what two structures?

Answer 2

Caudate nucleus & the putamen

Question 3

What are the appearances/orientations of the striatum’s structures?

Answer 3

Caudate - situated inferiority to the lateral ventricle
Putamen - inferior & lateral to the caudate

Question 4

The putamen can be considered to part of both the ______ and the _____ _____

Answer 4

Striatum & lenticular nucleus

Question 5

The ________ ________ is strictly part of the lenticular nucleus

Answer 5

Globus Pallidus

Question 6

A main function of the basal ganglia is to facilitate __________ movements and inhibiting ___________/___________ movement

Answer 6

Desired, undesired or competing

Question 7

The basal ganglia is not an ___________, but rather is a __________

Answer 7

Initiator, facilitator

Question 8

What does the motor region of the basal ganglia have in common with the primary motor cortex?

Answer 8

It’s got a lil homunculus!

Question 9

Where Parkinson’s is associated with a difficultly _______ing movements, Huntington’s is associated with a difficulty _______ing _______ movements

Answer 9

Initiating, inhibiting involuntary

Question 10

A basal ganglia disorder known as _______ is associated with difficulty inhibiting undesired movements (e.g. tics, verbal, thoughts)

Answer 10

Tourette’s

Question 11

The function of the direct pathway of the cortical-basal-ganglia-thalamic system is to?

Answer 11

Facilitates or encourages movement

Question 12

The function of the indirect pathway of the cortical-basal-ganglia-thalamic system is to?

Answer 12

Inhibits or suppresses movement

Question 13

Describe the process of the direct CBGTC system pathway

Answer 13

1. The cortex sends signals to the basal ganglia (specifically, a part called the striatum).
2. The striatum then sends inhibitory signals to another part of the basal ganglia called the globus pallidus internal (GPi), which normally inhibits the thalamus.
3. When the GPi is inhibited, it stops sending its inhibitory signals to the thalamus.
4. This allows the thalamus to send more excitatory signals back to the cortex, promoting movement.

Question 14

Describe the process of the indirect CBGTC system pathway

Answer 14

1. The cortex again sends signals to the striatum.
2. The striatum sends inhibitory signals to another part of the basal ganglia called the globus pallidus external (GPe).
3. When the GPe is inhibited, it reduces its inhibition on a part called the subthalamic nucleus (STN).
4. The STN can then send excitatory signals to the GPi, which increases its inhibitory output to the thalamus.
5. This leads to less excitation of the cortex, reducing movement.

Question 15

Describe the effect of Parkinson’s on the CBGTC system

Answer 15

Affects the direct pathway (bias in favour of the indirect pathway, net effect of inhibition)
Voluntary movement becomes harder to initiate rigidity, slowness of movement

Question 16

Describe the effect of Huntington’s disease on the CBGTC system

Answer 16

Affects the indirect pathway (bias in favour of the direct pathway, net effect of excitation)
movements are harder to inhibit; choreiform movement - involuntary continuous movements especially of the limbs

Question 17

Where is the substantia Nigra located?

Answer 17

In the midbrain (aka: mesencephalon)

Question 18

The substantia nigra produces _______

Answer 18

Dopamine

Question 19

Direct pathway striatal neurons have _____ dopamine receptors, which are _______ by dopamine

Answer 19

D1, excited

Question 20

Indirect pathway striatal neurons have ______ dopamine receptors, which are ________ by dopamine

Answer 20

D2, inhibited

Question 21

In someone with Parkinson’s how does the lack of dopamine influence the nigrostriatal pathway

Answer 21

Excitation of the Direct Pathway: With reduced dopamine, the direct pathway is less activated, leading to decreased facilitation of movement. Patients often experience difficulty initiating movement, known as bradykinesia.

Inhibition of the Indirect Pathway: The indirect pathway, which normally helps suppress excessive movement, becomes overactive. This further inhibits movement and can lead to rigidity and tremors.

Question 22

The subthalamic nucleus is part of the ________encephalon?

Answer 22

Di

Question 23

The subthalamic nucleus can be seen as an input nucleus to what structure?

Answer 23

Basal ganglia

Question 24

What structure has been seen to be a target for deep brain stimulation in Parkinson’s disease?

Answer 24

Subthalamic nucleus

Question 25

What structure has hard-to-define boundaries anatomically, but is thought to be associated with the basal ganglia regardless?

Answer 25

Nucelus accumbens

Question 26

The nucleus accumbens is located between what two structures?

Answer 26

Caudate and putamen

Question 27

The nucleus accumbens mediates what type of behaviour? It plays a role in what?

Answer 27

Goal-directed, addicition

Question 28

What are the 5 major subcortical white matter tracts?

Answer 28

1. Superior longitudinal fasciculus 2. Arcuate Fasciculus 3. Corpus Callosum 4. Internal capsule 5. Corona Radiata

Question 29

The superior longitudinal fasciculus has an important function in ___________________

Answer 29

Language processing

Question 30

Which of the 5 main white matter subcortical tracts is also known as part of the 4 SLF tracts?

Answer 30

Arcuate fasciculus

Question 31

What does the arcuate fasciculus connect?

Answer 31

Wernicke's to Broca's

Question 32

The ______ connects the two hemispheres

Answer 32

Corpus Callosum

Question 33

The corpus callosum is complete by age __, and growth continues until the ____ decade of life

Answer 33

4, 3rd

Question 34

What are the two major pathways of the corpus callosum?

Answer 34

Forceps Major & Forceps Minor

Question 35

Where is the forceps major pathway located?

Answer 35

Splenium (posterior part of CC)

Question 36

Where is the forceps minor pathway located?

Answer 36

Genu (anterior part of the corpus callosum)

Question 37

The splenium of the corpus callosum connects the ______ lobes of both hemispheres

Answer 37

Occipital

Question 38

The genu of the corpus callosum connects the ______ lobes of both hemispheres

Answer 38

Frontal

Question 39

The _______ connects the cerebral cortex with the subcortical structures, brainstem & spinal cord

Answer 39

Internal Capsule

Question 40

The Internal Capsule separates the _______ from the lenticular nuclei

Answer 40

Caudate

Question 41

T/F The internal capsule is unidirectional

Answer 41

F. Bidirectional - afferent and efferent

Question 42

The corona radiata can be described as fibres from the _______ radiating to various parts of the _______ and ________

Answer 42

Internal capsule, cerebral cortex, basal ganglia

Question 43

A nickname for the cerebellum is the?

Answer 43

Little brain

Question 44

T/F The cerebellum has its own gyri, sulci, and subcortical structures

Answer 44

T

Question 45

What separates the two cerebellar hemispheres

Answer 45

Vermis

Question 46

The cerebellum is part of the ________encephalon

Answer 46

Met

Question 47

The cerebellum is considered to be the largest _____ structure in the CNS

Answer 47

motor

Question 48

Which has more neurons: the cerebellum or the cortex?

Answer 48

Cerebellum

Question 49

What are the 3 nuclei of the cerebellum?

Answer 49

FID! Fastigial Interpositus Dentate

Question 50

The _____ cerebellar peduncle is the most medial, while the ______ cerebellar peduncle is the most lateral

Answer 50

Fastigial, Dentate

Question 51

Lesions in each of the three cerebellar nuclei could result in?

Answer 51

F - Loss of balance/positional sense, involuntary breathing/eye movements I - Tremor D - Ataxia

Question 52

The input and output to/from the cerebellum is controlled by the cerebellar _______

Answer 52

Peduncles

Question 53

Describe what each of the three cerebellar peduncles are responsible for

Answer 53

Superior (mostly output from Cb) Middle (mostly input to Cb via pons – movement and cognition) Inferior (mostly input to Cb via pons - vestibular)

Question 54

What are the three main principles to remember when thinking of the cerebellar peduncles?

Answer 54

- Receives input from specific CNS regions and sends information back to the same regions - Input and output preserve somatotopy of the cerebral cortex and other areas - Unlike the cerebral cortex, the cerebellum receives input from, and controls output to, the ipsilateral side of the body Therefore, damage to the cerebellum results in deficits to the ipsilateral side of the body

Question 55

Describe the 3 output zones of the cerebellar peduncles

Answer 55

Lateral zone: dentate nucleus - thalamus – cortex Intermediate zone: interpositus nucleus – red nucleus (midbrain – important for motor function) as well as thalamus Medial zone: fastigial nucleus – vestibular spinal cord region as well as thalamus

Question 56

Describe the ventral view of the brainstem (midbrain)?

Answer 56

Large lateral columns called cerebral peduncles (descending white matter) Continuation of the corticospinal and corticobulbar tracts

Question 57

The cerebral peduncles go up to the _______ and down to the _______

Answer 57

Internal Capsule, Pyramids

Question 58

Describe the dorsal view of the brain stem (midbrain)?

Answer 58

Superior and inferior colliculi

Question 59

The superior colliculi integrates what type of info for orientation of what parts of our body? What reflex is it responsible for?

Answer 59

Visual, auditory, and somatosensory Eyes & head Startle reflex

Question 60

Inferior Colliculi is a relay station of ______ stimuli from the ______ to the _______

Answer 60

Auditory, cochlea, cortex

Question 61

When thinking of the brainstem (midbrain) from a rostral POV, it merges with the ______encephalon

Answer 61

Die

Question 62

Describe what can be found inside the brainstem (midbrain)?

Answer 62

Substantia Nigra Cerebral aqueduct surrounded by the periaqueductal gray matter

Question 63

What is the periaqueductal gray involved with?

Answer 63

Involuntary vocalization and pain sensation

Question 64

Describe the dorsal POV of the Pons

Answer 64

Cerebellar peduncles & the pineal gland

Question 65

What can be found inbetween the cerebellar peduncles?

Answer 65

The origin of the 4th ventricle, this widens into the medulla portion of the ventricle

Question 66

What does the pineal gland produce?

Answer 66

Melatonin

Question 67

Describe the lateral POV of the pons?

Answer 67

Large root of CN V - trigeminal

Question 68

What can be found inside the pons?

Answer 68

Lateral & medial lemniscus

Question 69

What is a lemniscus?

Answer 69

A bundle of secondary sensory fibers in the brainstem

Question 70

The lateral lemniscus is part of the ______ pathway. It connects to the _______

Answer 70

Auditory, inferior colliculus

Question 71

The medial lemniscus is associated with ____, ____ and _____. It connects to the ____ and _____

Answer 71

touch, vibration & proprioception. Thalamus, cortex

Question 72

Describe the ventral aspect of the medulla oblongata

Answer 72

Pyramids! - prominent bundles of white matter

Question 73

T/F: 85-90% of the fibres of the pyramids cross the midline

Answer 73

T

Question 74

What can be found inside the medulla oblongata?

Answer 74

Cranial nerve nuclei (many of them involved with speech/swallowing (IX, X, XI, XII)

Question 75

Describe the dorsal aspect of the medulla oblongata

Answer 75

Fourth ventricle Fasciculus gracilis Fasciculus cuneatus Olive Central pattern generator networks

Question 76

The Fasciculus gracilis is associated with sensation from what body part?

Answer 76

Legs

Question 77

The Fasciculus cuneatus is associated with sensation from what body part?

Answer 77

Arms

Question 78

The Olive has connections to the what structure? It is responsible for integration of what type of info?

Answer 78

Cerebellum, motor/sensory, sound localization & analysis

Question 79

The central pattern generator plays a role in what actions?

Answer 79

Chewing, swallowing, and respiration

Question 80

Where does the spinal cord end?

Answer 80

Medullaris

Question 81

White matter of the spinal cord is on the _____, gray matter is _______

Answer 81

Periphery, centrally

Question 82

Describe the function of the dorsal horn & ventral horn gray matter

Answer 82

Dorsal horn gray matter - cell bodies that receive afferent input Ventral horn gray matter - cell bodies of the lower motor neurons

Question 83

Describe the white matter of the spinal cord (dorsally vs ventrally)

Answer 83

Dorsally - dorsal columns (afferent) Ventrally - corticospinal tract (efferent)

Question 84

What type of cell bodies are in the spinal cord? What about outside the spinal cord in a spinal ganglion?

Answer 84

1) motor 2) sensory

Question 85

What happens to voluntary movements with damage to upper motor neurons? What pyramidal tract is this associated with?

Answer 85

Spasticity, stronger reflexes, muscle weakness The pyramidal tract

Question 86

What happens with posture & tone after damage to the upper motor neurons? What pyramidal tract is this associated with?

Answer 86

weakness, reduced reflexes, decreased muscle tone The extrapyramidal tract

Question 87

Damage to lower motor neurons results in:

Answer 87

(e.g., progressive muscular atrophy, poliomyelitis): Loss of muscle innervation: diminished reflexes, muscle wasting, weakness/paresis

Question 88

The cortico-spinal (pyramidal) tract controls what?

Answer 88

Primary voluntary motor activity

Question 89

What is the origin of the cortico-spinal tract?

Answer 89

Primary motor and somatosensory cortex

Question 90

Describe the path of the cortico-spinal tract

Answer 90

Upper motor neurons are in the cortex -> project through the corona radiata to the internal capsule -> cerebral penduncles -> pyramids of the medulla -> travel to spinal cord to synapse on the lower motor neurons

Question 91

Most fibres of the corticospinal tract cross - they continue as what? They control what?

Answer 91

Lateral corticospinal tract - arms and legs

Question 92

The fibres of the corticospinal tract that do not cross over form what? They control what?

Answer 92

Anterior corticospinal tract - head & trunk

Question 93

What is a dermatome?

Answer 93

area of the body innervated by the neurons in single dorsal root

Question 94

What is a myotome?

Answer 94

muscles or parts of the muscle innervated by a single ventral root

Question 95

What are the significances of sciatica, chickenpox, and shingles in relation to the spinal cord?

Answer 95

Some health conditions that manifest themselves along dermatomes. May feel excessive pain in specific "bands" of the body because they are attacking specific dermatomes