chapter 2: Basic principles of sensory physiology Flashcards
Name the basic properties of action potential
- propagated response
- remains the same size no matter the intensity
- firing rate of AP depends on stimulus intensity
- refractory period
- spontaneous activity
What is the voltage of a neuron during its resting potential?
-70mV compared to the outside
What is the voltage of a neuron during its action potential?
+40mV compared to the outside
A neuron receives electrical signal from
a. cell body
b. dendrites
c. axon
d. nerve ending
b. dendrites
True or false? The falling phase of an action potential occurs when there is depolarization of the neuron
False, it occurs when there is hyperpolarization of the neuron
Explain how an action potential can be initiated
- signal approaches → opens Na+ channels: Na+ flows in axon
- depolarization
- Na+ channels close, K+ channels open: K+ rushes out
- hyperpolarization
- sodium-potassium pump ensures Na+ doesn’t build up inside and K+ doesn’t build up outside
How long does an action potential lasts
1 millisecond
if action potentials are always the same size, how is it possible to detect the intensity of a stimuli
intensity is transmitted by frequency of the action potential (rate of firing)
Explain how information is transmitted between two neurons
- AP reaches end of axon: releases NT
- NT received on receptor sites of receiving neuron
- if NT matches receptor site: triggers new electrical signal
define specificity coding
specialized neuron that responds to only one concept or stimulus
define sparse coding
stimulus is represented by a pattern of firing of only a small group of neurons
define population coding
stimulus represented by a pattern of firing across a large number of neurons
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
d. none of the above
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
b. repolarization of the membrane
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
a. binding to post-synaptic receptors
True or false? sensory AP can occur in the absence of a physical stimulus
True
true or false? MRI reveals brain structures, while fMRI reveals how brain ‘functions’ activate different brain areas
true
what are the key components of a neuron and what are their functions
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
what is the definition of an action potential
signal identified by the predictable rise and fall of the change inside the axon relative to the outside
if neurons are bathed in a liquid solution, how are they capable of transmitting electrical signals
liquid solution is rich in ions, which are molecules that carry an electrical charge
where are the NT stored in the sending neuron before they are released
synaptic vesicles
what are the two types of responses that can occur at the NT receptor sites?
excitatory: when neuron becomes depolarized
inhibitory: when neuron becomes hyperpolarized
does an excitatory or inhibitory response automatically triggers an action potential?
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
how do you record electrical signals from a single neuron
- 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
what is the grandmother cell
idea that a specific cell would respond to your grandmother, whether upside down, diagonal, looking at a picture or just the thought of her
define modularity
the idea that specific brain areas are specialized to respond to specific types of stimuli or functions
- each area is called a module
what is known as the Broca’s area
speech production area
what is known as the Wernicke’s area
understanding speech area
what is neuropsychology
study relating location of brain damage to specific effects on behavior
differentiate between MRI and fMRI
MRI: detects tumors and brain abnormalities
fMRI: determines how various types of cognition activate different areas of the brain
how does fMRI determines which brain region is active
- hemoglobin carries oxygen & iron (magnetic)
- when brain region active, it loses oxygen so hemoglobin becomes more magnetic
- response increases towards magnetic field of fMRI
when was the superior temporal sulcus (STS) activated
responds more to vocal sounds than non-vocal sounds
define the concept of distributed representation
brain represents info in patterns distributed across the cortex, rather than in one single brain area
differentiate between structural and functional connectivity
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
what is the resting-state method of measuring functional connectivity
- use task-related fMRI to determine brain location associated with specific task
- measure resting-state fMRI at seed location
- measure resting-state at another location (test location)
- calculate correlation between seed and test location responses
- high correlation = high functional connectivity
how does functional connectivity help us understand perception
can be used to predict behavior
