Neuroanatomy

Question 1

What is typical entry point?

Answer 1

traverses gyri SMA (supplementary motor area)

Question 2

What is the outer part of the brain called?

Answer 2

cortex, cortical surface of the brain

Question 3

What do you want to avoid when entering the brain?

Answer 3

primary motor cortex, ventricles and sulci

Question 4

What are sulci?

Answer 4

valleys, very vascular, not good to enter here

Question 5

What are gyri?

Answer 5

mountains/hills, good place to enter because less risky

Question 6

What is the coronal suture?

Answer 6

Where 2 plates come together, dip in skull, make burr hole here, keeps you close to SMA and away from primary motor cortex

Question 7

What is AC?

Answer 7

anterior commisure, runs across, looks like handle bars

Question 8

What are commisures?

Answer 8

good guides and reference points because everyone has them, similar from person to person, easy to get to functional targets, white matter fiber bundles, crossing from L to R hemisphere of the brain

Question 9

What is PC?

Answer 9

posterior commisure

Question 10

The distal contact is the most \_\_\_ in the brain?
posterior
anterior
dorsal
ventral

Answer 10

ventral

Question 11

What is the pineal gland?

Answer 11

sits above the PC, good landmark

Question 12

What areas are involved in typical trajectory?

Answer 12

cortex
striatum (Caudate) or internal capsule
thalamus
Zona Inserta or Fields of Forel (grey matter)
STN
SNr

Question 13

What part of the STN is typically best to stimulate?

Answer 13

motor, dorsal and lateral

dorsolateral

Question 14

What is a typical DBS lead trajectory?

Answer 14

pre-coronal entry point passes through the prefrontal cortex, subcortical white matter, the anterior limb of the internal capsule and the basal ganglia

Question 15

What are the divisions of the STN? Why is this important?

Answer 15

Emotional/Limbic
Motor/Movement
Cognitive
We don’t just want to blow up the STN with energy, we generally want to be in the motor part of STN, the dorsal lateral portion, this is why we do MER

Question 16

What is the anterior division of the STN responsible for?

Answer 16

emotional

Question 17

What is the dorsal lateral division of the STN responsible for?

Answer 17

motor/movement (largest)

Question 18

What is the medial part of the STN responsible for?

Answer 18

cognitive (associative)

Question 19

What is halfway between the AC and PC?

Answer 19

Mid commisural (MC)

Question 20

What are the typical coordinate for STN from MC?

Answer 20

Lateral: 12mm
Inferior: 3mm center of motor (STN), 4-5mm bottom of nucleus
Posterior: 3mm

Question 21

What 2 parts of the brain make up the striatum? How do you describe what they look like?

Answer 21

Caudate and Putamen, caudate looks like a snake and the putamen looks like an egg that the caudate wraps around

Question 22

What is the lemon wedge shape of matter above the pallidus?

Answer 22

Putamen

Question 23

What lies lateral to the STN? (dark matter)

Answer 23

posterior limb of internal capsule (IC)

Question 24

What lies on the other side lateral to the Internal Capsule? (STN on one side, what’s on the other)

Answer 24

globus pallidus

Question 25

What separates the lobes of the brain?

Answer 25

fissures

Question 26

what are the 4 lobes of the brain?

Answer 26

frontal, parietal, occipital, temporal

Question 27

Which lobe is associated with reasoning, motor skills, and expressive language?

Answer 27

frontal

Question 28

T/F Substantia Nigra is a main target for DBS Surgery.

Answer 28

F

Question 29

Which lobe do surgeons generally attempt to pass the lead through?

Answer 29

frontal lobe

Question 30

Explain the direct vs indirect pathway.

Answer 30

Direct Pathway: cortex-striatum-thalamus overall effect: facilitates movement Indirect Pathway: cortex-striatum-GPe-STN-GPi-thalamus overall effect: inhibits movement

Question 31

What is the trajectory once the physician is in the STN?

Answer 31

Thalamus: 20mm TO START Zona Inserta: 8mm STN: 4-5mm (or higher) SNr: 1mm below target

Question 32

What is STN target for DBS?

Answer 32

dorsal and lateral

Question 33

What are the indirect coordinates for targeting the GPI?

Answer 33

We are targeting the lateral, inferior border (medial would be the internal capsule) Lateral: 17.5mm from the wall of the 3rd ventricle Anterior: 2mm from MC Inferior: 5mm from MC

Question 34

What are the indirect coordinates for targeting ViM

Answer 34

Lateral: 11.5mm Posterior: 2 1/2 - 3 1/2 mm fraction of the AC/PC line length Anterior: to the PC

Question 35

What is ring mode and why is this important?

Answer 35

single source, when using more than 1 contact, is not voltage controlled or current controlled, it is impedance controlled, MICC is true ring mode because you can control energy circumferentially`

Question 36

What are the components of the Basil Ganglia?

Answer 36

Caudate: striatum and putamen Globus Pallidus: GPe and GPi Subthalamic Nucleus: STN Substantial Nigra: SNr

Question 37

What is a neuron?

Answer 37

cells that transmit information: sensory, motor and interneurons, in general motor neurons control the symptoms associated with PD

Question 38

Explain neuron communication

Answer 38

- dendrites collect electrical signals, receivers - cell body integrates incoming signals and generates outgoing signal to axon - axon: passes electrical signals to dendrites of another cell (transmitters)

Question 39

What are the four distinct phases of an action potential?

Answer 39

resting sate: neuron is not sending signals and inside of the cell has a negative charge depolarizing state: a stimulus causes the sodium channels to open, the negatively charged neuron causes positive sodium ions to rush in, the inside of the neuron becomes momentarily positively charged and its said to be depolarized repolarizing state: the depolarization of the neuron leads to the opening of the potassium channels, allowing positive ions to leave the cell, the cell is back in the negative range undershoot: refractory period since it is the very short period when another action potential is not possible