chapter 2: Basic principles of sensory physiology

Question 1

Name the basic properties of action potential

Answer 1

1. propagated response
2. remains the same size no matter the intensity
3. firing rate of AP depends on stimulus intensity
4. refractory period
5. spontaneous activity

Question 2

What is the voltage of a neuron during its resting potential?

Answer 2

-70mV compared to the outside

Question 3

What is the voltage of a neuron during its action potential?

Answer 3

+40mV compared to the outside

Question 4

A neuron receives electrical signal from
a. cell body
b. dendrites
c. axon
d. nerve ending

Answer 4

b. dendrites

Question 5

True or false? The falling phase of an action potential occurs when there is depolarization of the neuron

Answer 5

False, it occurs when there is hyperpolarization of the neuron

Question 6

Explain how an action potential can be initiated

Answer 6

1. signal approaches → opens Na+ channels: Na+ flows in axon
2. depolarization
3. Na+ channels close, K+ channels open: K+ rushes out
4. hyperpolarization
5. sodium-potassium pump ensures Na+ doesn’t build up inside and K+ doesn’t build up outside

Question 7

How long does an action potential lasts

Answer 7

1 millisecond

Question 8

if action potentials are always the same size, how is it possible to detect the intensity of a stimuli

Answer 8

intensity is transmitted by frequency of the action potential (rate of firing)

Question 9

Explain how information is transmitted between two neurons

Answer 9

1. AP reaches end of axon: releases NT
2. NT received on receptor sites of receiving neuron
3. if NT matches receptor site: triggers new electrical signal

Question 10

define specificity coding

Answer 10

specialized neuron that responds to only one concept or stimulus

Question 11

define sparse coding

Answer 11

stimulus is represented by a pattern of firing of only a small group of neurons

Question 12

define population coding

Answer 12

stimulus represented by a pattern of firing across a large number of neurons

Question 13

which of the following is true about all neurons
a. they’re inhibitory
b. they’re excitatory
c. they transmit sensory information
d. none of the above

Answer 13

d. none of the above

Question 14

the opening of voltage-gated K+ channels (on the axon) is responsible for which part of the AP?
a. depolarization of the membrane
b. repolarization of the membrane
c. release of NT from vesicles
d. the resting membrane potential

Answer 14

b. repolarization of the membrane

Question 15

once released, NT typically produce signals in postsynaptic neurons by:
a. binding to post-synaptic receptors
b. binding to pre-synaptic receptors
c. entering the post-synaptic neuron
d. attaching to vesicles

Answer 15

a. binding to post-synaptic receptors

Question 16

True or false? sensory AP can occur in the absence of a physical stimulus

Answer 16

True

Question 17

true or false? MRI reveals brain structures, while fMRI reveals how brain ‘functions’ activate different brain areas

Answer 17

true

Question 18

what are the key components of a neuron and what are their functions

Answer 18

cell body: contains mechanisms to keep the cell alive
dendrites: branch out from cell body to receive electrical signals
axon: filled with fluid that conducts electrical signals

Question 19

what is the definition of an action potential

Answer 19

signal identified by the predictable rise and fall of the change inside the axon relative to the outside

Question 20

if neurons are bathed in a liquid solution, how are they capable of transmitting electrical signals

Answer 20

liquid solution is rich in ions, which are molecules that carry an electrical charge

Question 21

where are the NT stored in the sending neuron before they are released

Answer 21

synaptic vesicles

Question 22

what are the two types of responses that can occur at the NT receptor sites?

Answer 22

excitatory: when neuron becomes depolarized
inhibitory: when neuron becomes hyperpolarized

Question 23

does an excitatory or inhibitory response automatically triggers an action potential?

Answer 23

no, it increases/decreases the chances a neuron will generate an AP. if enough NT generate an excitatory response, then an AP will be triggered

Question 24

how do you record electrical signals from a single neuron

Answer 24

• recording electrode shown with its recording tip inside the neuron
• reference electrode further away
• both connected to a meter that records the difference in charge between them

Question 25

what is the grandmother cell

Answer 25

idea that a specific cell would respond to your grandmother, whether upside down, diagonal, looking at a picture or just the thought of her

Question 26

define modularity

Answer 26

the idea that specific brain areas are specialized to respond to specific types of stimuli or functions
- each area is called a module

Question 27

what is known as the Broca’s area

Answer 27

speech production area

Question 28

what is known as the Wernicke’s area

Answer 28

understanding speech area

Question 29

what is neuropsychology

Answer 29

study relating location of brain damage to specific effects on behavior

Question 30

differentiate between MRI and fMRI

Answer 30

MRI: detects tumors and brain abnormalities
fMRI: determines how various types of cognition activate different areas of the brain

Question 31

how does fMRI determines which brain region is active

Answer 31

• hemoglobin carries oxygen & iron (magnetic)
• when brain region active, it loses oxygen so hemoglobin becomes more magnetic
• response increases towards magnetic field of fMRI

Question 32

when was the superior temporal sulcus (STS) activated

Answer 32

responds more to vocal sounds than non-vocal sounds

Question 33

define the concept of distributed representation

Answer 33

brain represents info in patterns distributed across the cortex, rather than in one single brain area

Question 34

differentiate between structural and functional connectivity

Answer 34

structural: “road map” of fibers connecting different areas of the brain
functional: neural activity associated with a particular function that is flowing through the structural network

Question 35

what is the resting-state method of measuring functional connectivity

Answer 35

1. use task-related fMRI to determine brain location associated with specific task
2. measure resting-state fMRI at seed location
3. measure resting-state at another location (test location)
4. calculate correlation between seed and test location responses
   - high correlation = high functional connectivity

Question 36

how does functional connectivity help us understand perception

Answer 36

can be used to predict behavior