Quiz 1: EEG, Action Potential, Neurons, Brain Anatomy

Question 1

Purpose of dendrites

Answer 1

Receives information/signals from other neurons

Question 2

Purpose of cell body (a.k.a. soma)

Answer 2

Process and integrates received information/signal from dendrites

Question 3

Purpose of axon

Answer 3

Joins to the cell body at junction called axon hillock. Carries signals across long distances from one part of the neuron to another. Covered in Myelin sheath that allows more rapid transmission by jumping along nodes of Ranvier between Schwann cells

Question 4

Purpose of axon terminal

Answer 4

Transmits signal to next cell in the chain

Question 5

What is the synapse?

Answer 5

Gap between the axon of one neuron and the dendrite of the next. Presynaptic is the axon neuron and postsynaptic is the dendrite neuron.

When action potential arrives from presynaptic neuron, it causes neurotransmitters to be released in the synaptic cleft . These bind to ionic channels of the postsynaptic neuron and opens the channel.

Question 6

Describe the membrane potential at rest

Answer 6

Abundant sodium (+) outside cell, abundant potassium (-) inside cell, electrochemical equilibrium, -70mV

Question 7

Describe graded potential

Answer 7

Neuron was not stimulated enough to reach threshold of membrane potential. Resulting change can be positive or negative. Neuron uses sodium-potassium pump to restore back to resting state

Question 8

Describe depolarization

Answer 8

When the stimulus is high and passes the threshold of -55mV, the axon hillock is triggered.

Sodium channel opens > membrane potential becomes more positive > goes to overshoot/action potential > sodium channel closes

Question 9

Describe repolarization

Answer 9

Action potential was achieved and sodium channel closes > potassium channel opens > membrane potential becomes more negative > because potassium channel is slower to close it hits hyperpolarization (pass resting state) > potassium channel closes

Question 10

How does membrane potential go back to resting state when it is at hyperpolarization?

Answer 10

Sodium-Potassium channel continues to pump until membrane potential reaches resting.

Question 11

What is absolute refractory period?

Answer 11

During repolarization when the sodium channel closes, the neuron cannot fire no matter how strong the stimulus. This prevents action potentials from happening too quickly of signals to travel backwards down the axon

Question 12

What is the relative refractory period?

Answer 12

During hyperpolarization, the sodium channel could open but it takes a larger stimulus to reach the threshold.

Question 13

Does action potential amplitude change for a neuron?

Answer 13

No, even with a larger stimulus. The frequency can change based on the intensity, for example the rate is faster for intense pain versus a breeze

Question 14

Ions move through channels through passive diffusion. What type of ion channels are there?

Answer 14

Voltage-gated : based on membrane potential

Ligand : bounded by type of molecule

Mechanical : external forces or movement

Question 15

Inhibitory vs Excitatory Synapses

Answer 15

Inhibitory temporarily decreases the membrane potential of the postsynaptic cell. Excitatory temporarily increases

Question 16

What is synaptic plasticity? What are the different types?

Answer 16

Neurons change the strength of the connections between themselves.

LTP (long term potentiation): If neuron A is consistently involved in causing neuron B to fire, the strength of the connection between the increases

LTD (long term depression): decrease strength due to uncorrelated firing

STDP (spike timing dependent plasticity): presynaptic spike occurs slightly before the post-synaptic, the strength increases. If it occurs slightly after, the strength decreases

STD (short term depression): successive spike causes lesser change in potential until equilibrium

STF (short term facilitation): successive spike has a larger effect than predecessor until saturation point

Question 17

What is central nervous system (CNS)?

Answer 17

Consist of brain(clusters of neurons- nuclei, separated into two cerebral hemispheres, distributed and localized) and spinal cord (pathway to convey signals from brain to muscles).

Question 18

What is the brain stem?

Answer 18

Consist of medulla, pons and midbrain. It conveys all information from brain to rest of the body.

Medulla and pons: basic regulatory functions like sleep and breathing

Midbrain: Eye movement, reflexes, pain perception

Question 19

What is the brain’s cerebellum?

Answer 19

Highly structures network of neurons located at the base of the brain for movement coordination

Question 20

What is the brain’s thalamus?

Answer 20

“relay station” that conveys info from sensory organs to neocortex (consist of billions of neurons)

Question 21

What is the brain’s basal ganglia?

Answer 21

motor control and action selection

Question 22

What is the brain’s amygdala?

Answer 22

Regulation of emotions

Question 23

What is the brain’s hippocampus?

Answer 23

memory and learning

Question 24

What is EEG?

Answer 24

Electroencephalography
- neuron firing within brain
- thousands of neuron firing patterns

Question 25

What is EMG?

Answer 25

Electromyography
- skeletal muscle nerve signals
- easily evoked

Question 26

What is an invasive BCI?

Answer 26

Electrocorticography (ECOG)
- electrodes under the skull

Question 27

EMG vs EEG, why EEG?

Answer 27

EMG is figuring out how to move one area to control another whereas EEG is natural

Question 28

What are the different stages to reach action potential?

Answer 28

Rest > gradient potential (failed initiation) > threshold (achieved initiation) > depolarization > action potential / overshoot> repolarization> hyperpolarization > rest

Question 29

What is the peripheral nervous system (PNS)?

Answer 29

Somatic: skeletal muscles and sensory organs

Autonomic: pumping of heart, breathing

Question 30

What are the frontal lobes?

Answer 30

movement, expressive language, planning, judgement, decisions, attention

Question 31

What are the parietal lobes?

Answer 31

sensory processing, navigation, control, size judgment, interpretation (math and language)

Question 32

What are the temporal lobes?

Answer 32

memory, perception, emotions, remembering verbal info, speech recognition

Question 33

What are the occipital lobes?

Answer 33

color and visuals

ventral stream: “what” of vision

dorsal stream: “where/how”

Question 34

What is the homunculus?

Answer 34

motor or sensory distribution along cerebral cortex

Question 35

What is the 10-20 system?

Answer 35

Layout to place electrodes. These are the intervals to place between the Naison and Inion

Naison 10%, 20%, 20%, 20%, 20%, 10% Inion

Question 36

How to record EEG?

Answer 36

Use differential amplifier to amplify small voltage ( 2 electrode readings -> 1 channel)

Question 37

What is EEG Bipolar Montage vs Common Average Reference Montage?

Answer 37

Bipolar: subtract ECG from raw data (5 electrodes -> 4 channels)

Common: compare voltage of electrode of average across electrodes

Question 38

What are biopotential electroides?

Answer 38

Electrodes serve as transducer to change an ionic current into an electronic current. Body current is carried by ions and electrode it is carried by electrons

Question 39

What is the electrode-electrolyte interface?

Answer 39

Current crosses from left to right. Electrode consists of compatible metallic atoms. Electrolyte is aqueous. Current passes from electrode to electrolyte.

Electrons move in opposite direction of current in electrode. Cations move in same direction as current. Anions move in opposite direction of current in electrolyte.

Cation discharged into electrolyte. Anion oxidized and electrons freed to electrode.

Potential difference between electrode and electrolyte (voltage)

Question 40

How does circuits model biopotential electrodes?

Answer 40

DC-bias > Voltage divider (Current Divider > Resistor)