Brain and EEG

Question 1

What part of the nervous system does an EEG measure?

Answer 1

Central nervous system

Question 2

What is a synapse?

Answer 2

Junction between two nerve cells

Question 3

What happens at the synapse (in terms of signals)?

Answer 3

An electrical signal is converted into a chemical signal

Question 4

What chemicals are found in the synapse?

Answer 4

Neurotransmitters

Question 5

How is a chemical signal converted into an electrical signal?

Answer 5

Makes it more likely to initiate an action potential (ion channels)

Question 6

What is an excitatory neurotransmitter?

Answer 6

Makes it easier to have an action potential (depolarization)

Question 7

What is an inhibitory neurotransmitter?

Answer 7

Makes it harder to have an action potential (hyperpolarization)

Question 8

What is a hyperpolarization?

Answer 8

Negative ions flow into the cell, making it harder to have an action potential

Question 9

What are the two advantages of chemical signaling?

Answer 9

Signal amplification and signal computation

Question 10

What is signal amplification?

Answer 10

Chemicals can interact with many neurons, and thus amplify the signal

Question 11

What is signal computation?

Answer 11

Can integrate different signals to generate a calculated response

Question 12

What are the two advantages of electrical signaling?

Answer 12

Speed and certainty

Question 13

What ends the signal in a synapse?

Answer 13

Transporters

Question 14

How does SSRI (Selective Serotonin Reuptake Inhibitor) work?

Answer 14

Blocks serotonin transporters, keeping serotonin in the synapse

Question 15

What is SSRI used to treat?

Answer 15

Depression (imbalance of serotonin)

Question 16

How does the brain get neurotransmitters?

Answer 16

It makes its own

Question 17

How do drugs of abuse work?

Answer 17

Block transporters (dopamine) to keep the high feeling

Question 18

What makes a drug addictive?

Answer 18

Kinetics (doesn’t stay stuck to the transporter)

Question 19

What does encephalo mean?

Answer 19

Related to the brain

Question 20

What system is used to put electrodes on the scalp for EEG?

Answer 20

10/20 system

Question 21

How can the resolution be increased in an EEG?

Answer 21

More electrodes (10/10 system)

Question 22

What signals are read by an EEG?

Answer 22

Post synaptic potentials in the cortex

Question 23

How are pyramidal cells oriented?

Answer 23

Vertically (no crisscrossing)

Question 24

What is the significance of the pyramidal cells orientation?

Answer 24

Allows for the signals to be read (no canceling out)

Question 25

What is a PSP?

Answer 25

Post-synaptic potential

Question 26

Why are PSPs measured by an EEG?

Answer 26

Action potentials are very short, but PSPs are much longer; PSPs have a larger ampitude

Question 27

What is synchronization (EEG)?

Answer 27

Pyramidal cells firing at the same time

Question 28

What happens if neurons are firing synchronously (in terms of frequency)?

Answer 28

Lower frequency

Question 29

What happens if neurons are firing asynchronously (in terms of frequency)?

Answer 29

Higher frequency

Question 30

If an excitatory signal originates at the scalp, what deflection is measured?

Answer 30

Upward (more negative towards the scalp)

Question 31

If an excitatory signal originates deep in the brain, what deflection is measured?

Answer 31

Downward (more positive towards the scalp)

Question 32

If an inhibitory signal originates at the scalp, what deflection is measured?

Answer 32

Downward (more positive towards the scalp)

Question 33

If an inhibitory signals originates deep in the brain, what deflection is measured?

Answer 33

Upward (more negative towards the scalp)

Question 34

If an excitatory signal originates at the scalp, what direction is the polarization moving?

Answer 34

A depolarization is moving towards the base

Question 35

If an excitatory signal originates at the base, what direction is the polarization moving?

Answer 35

A depolarization is moving towards the scalp

Question 36

If an inhibitory signal originates at the scalp, what direction is the polarization moving?

Answer 36

A hyperpolarization is moving towards the base

Question 37

If an inhibitory signal originates at the base, what direction is the polarization moving?

Answer 37

A hyperpolarization is moving towards the scalp

Question 38

What determines the magnitude of the EEG?

Answer 38

The gradient and location of the PSPs

Question 39

Which PSPs have a higher gradient?

Answer 39

Excitatory

Question 40

Which PSPs have a lower gradient?

Answer 40

Inhibitory

Question 41

What is the dipole due to a depolarization wave?

Answer 41

- -----> +

Question 42

What is the dipole due to a hyperpolarization wave?

Answer 42

+ -----> -

Question 43

What is meant by fortuitous neural architecture?

Answer 43

Orientation of pyramidal cells allows for EEG recordings (signals do not cancel out)

Question 44

If there is a positive deflection in EEG, what voltage is the electrode sensing (positive or negative)?

Answer 44

Negative

Question 45

If there is a negative deflection in EEG, what voltage is the electrode sensing (positive or negative)?

Answer 45

Positive

Question 46

What brain waves have the highest frequency?

Answer 46

Beta waves

Question 47

What brain waves have the lowest freqiency?

Answer 47

Delta waves

Question 48

What brain waves have the second highest frequency?

Answer 48

Alpha waves

Question 49

What brain waves have the second lowest frequency?

Answer 49

Theta waves

Question 50

What is the relationship between frequency and consciousness?

Answer 50

As frequency increases, consciousness increases

Question 51

When are the neurons most synchronous?

Answer 51

During deep sleep (lowest frequency)

Question 52

How is an EEG signal modeled?

Answer 52

Cylinder with parameters of P, S, and phi

Question 53

In the EEG model, what does r represent?

Answer 53

Location of cortical column (within the brain)

Question 54

In the EEG model, what does w represent?

Answer 54

Volume that current source takes up

Question 55

In the EEG model, what does t represent?

Answer 55

Time

Question 56

In the EEG model, what does P represent?

Answer 56

Dipole moment (per unit volume)

Question 57

In the EEG model, what does P depend on?

Answer 57

r (location) and t (time)

Question 58

In the EEG model, what does S represent?

Answer 58

Local volume source current

Question 59

In the EEG model, what does S depend on?

Answer 59

r (location), w (current sources), and t (time)

Question 60

In the EEG model, what does phi represent?

Answer 60

Potential at the scalp

Question 61

In the EEG model, what does phi depend on?

Answer 61

r (location) and t (time)

Question 62

In the EEG model, what does W represent?

Answer 62

Volume

Question 63

In the EEG model, how is the total dipole moment calculated?

Answer 63

Volume integral of product of volume of current sources (w) and local volume current (s), normalized by the total volume

Question 64

In the EEG model, how is the scalp potential calculated?

Answer 64

Integral over all cylinders of product of dipole moment (P) and Green's function (G)

Question 65

In the EEG model, what does the Green's function represent?

Answer 65

Relates the contribution of the unit source to the contribution to the scalp potential

Question 66

In the EEG model, what does the Green's function take into account?

Answer 66

Geometric contributions and conductivity contributions

Question 67

In the EEG model, what do the integrals act as (generally)?

Answer 67

Weighted sums over a particular property

Question 68

In the EEG model, what does a higher frequency represent?

Answer 68

More complicated pattern at the scalp

Question 69

How can an eye blink alter an EEG signal?

Answer 69

Eye is a dipole, which can be picked up by the EEG

Question 70

What is alpha blocking?

Answer 70

When a person's eyes are open, the alpha waves disappear

Question 71

What is epilepsy?

Answer 71

Neurological disorder based on unpredictable, recurrent seizures

Question 72

What are seizures?

Answer 72

Synchronous and excessive excitement of neurons

Question 73

How are seizures visualized in an EEG signal?

Answer 73

Large areas of firing (large spikes)

Question 74

What is Vagus Nerve Stimulation (VNS)?

Answer 74

Sending pulses to the vagus nerve to prevent seizures

Question 75

What is the vagus nerve?

Answer 75

A large cranial nerve that is the subject of VNS ("pacemaker" of the brain)

Question 76

Why is the vagus nerve a good target for clinical treatment?

Answer 76

Affects many different areas and neurotransmitters

Question 77

What is Electroconvulsive Therapy (ECT)?

Answer 77

Currents are put into the brain to start a seizure

Question 78

How is ECT thought to work?

Answer 78

Change of brain chemistry to "reset"

Question 79

What do VNS and ECT have in common?

Answer 79

Both affect large areas of the brain to act as a treatment

Question 80

What neurotransmitter is important in auditory perception?

Answer 80

Serotonin

Question 81

What does LDAEP stand for?

Answer 81

Loudness Dependence of Auditory Evoked Potentials

Question 82

What could LDAEP be correlated with?

Answer 82

Levels of serotonin in serotonin neurons

Question 83

What could be a clinical use of LDAEP?

Answer 83

Diagnose who could benefit from SSRI (who has an imbalance of serotonin)

Question 84

What is usually treated with DBS?

Answer 84

Parkinson's Disease

Question 85

What is Deep Brain Stimulation (DBS)?

Answer 85

Stimulating a section deep within the brain for a clinical effect

Question 86

Why is DBS useful for Parkinson's?

Answer 86

Parkinson's is localized based on specific dopaminergic neurons, which can be stimulated

Question 87

Why is brain signaling complicated clinically (such as in Parkinson's)?

Answer 87

Parts of the brain can excite and inhibit each other

Question 88

What is the general rule of the brain (in terms of concentrations)?

Answer 88

Balance is critical

Question 89

What is MEG?

Answer 89

Measures magnetic charges of the brain

Question 90

What is the advantage of MEG over EEG?

Answer 90

Could measure magnetic signals if the brain was filled with air (could not measure electrical signals)

Question 91

What magnetic dipoles are measured by MEG?

Answer 91

Dipoles that are tangential to the scalp (produce vertical magnetic fields)