Chapter 2 Flashcards
cells that convey sensory information into the brain, carry out operations, and transmit commands to the body
neurons
specialized neurons that respond to specific kinds of energy
Sensory receptors
a state in which there is a difference in electrical charge between the inside and outside of the neuron
Polarization
measure of the difference in electrical charge between two points
Voltage
difference in charge between inside & outside of membrane of a neuron at rest
Resting potential
abrupt depolarization of membrane that allows neuron to communicate, Lasts about 1 millisecond
When neurons are “firing,”-Axon hillocks
Action potential
What do we use to Record Electrical Signals in Neurons
Small electrodes are used to record from single neurons
Recording electrode
Inside the nerve fiber
Reference electrode
Outside the nerve fiber
Meter
Records the difference in charge between the tips of the two electrodes
Properties of Action Potentials
Show propagated response
Remain the same size regardless of stimulus intensity
Increase in rate to increase in stimulus intensity
Show spontaneous activity that occurs without stimulation, baseline, detect an increase or decrease- check the baseline
Properties of Action Potentials- Show propagated response
Once the response is triggered, it travels down the full length of the axon without changing in size
Properties of Action Potentials-Increase in rate to increase in stimulus intensity
Have a refractory period of 1 ms – upper firing rate is 500 to 800 impulses per second
All or none law
once the action potential it’s going to occur at its full strength or not at all (not partial)
Non decremental use
when the action potential travels, they don’t decrease in size as they go
What Moves the Ions?
1- Force of diffusion
2-Electrostatic pressure
3- Sodium potassium pump
Force of diffusion
tendency of ions to move through high concentrated membrane to less concentrated side
Electrostatic pressure
force where ions are repelled from similarly charged, attracted to oppositely charged
Sodium potassium pump
large protein molecules that move sodium ions through cell membrane to outside, potassium ions back inside
Ion channels
gated pores in the membrane formed by proteins; limit the flow of ions into and out of the cell
Ion Channels Can be _____ or ____
chemically gated, electrically gated
Chemically gated
neurotransmitters or hormones
Electrically
change in electrical potential of the membrane
Where are the neurotransmitters stored at
synaptic vesicles
Synapse
the connection between two neurons
Synaptic cleft:
the small gap which separates neurons so they are not in direct physical contact at the synapse
Presynaptic is the_____ neuron
transmitting neuron
Postsynaptic is the ___ neuron
receiving neuron
Two types of responses
can occur at the receptor sites
1- excitatory
2- inhibitory
Excitatory transmitters
cause depolarization
Neuron becomes more positive
Increases the likelihood of an action potential
Inhibitory transmitters
cause hyperpolarization
Neuron becomes more negative
Decreases the likelihood of an action potential
Specificity coding
A specialized neuron that responds only to one concept or stimulus
Sparse coding
occurs when a particular
stimulus is represented by a pattern of firing of only a small
group of neurons, with the majority of neurons remaining
Population coding
proposes that our experiences are represented by the pattern of firing across a large number of neurons
A large number of stimuli can be represented, because large groups of neurons can create a huge number of different patterns
Modularity:
the idea that specific brain areas are specialized to respond to specific types of stimuli or functions
Each specific area is called a module
Phrenology
is a process that involves observing and/or feeling the skull to determine an individual’s psychological attributes
speech production area
Broca’s area
area in the temporal lobe which was involved in understanding speech
Wernicke’s area
Distributed representation:
idea that the brain represents information in patterns distributed across the cortex, not just one brain area
The distributed approach to representation focuses on the activity in multiple brain areas and the connections between those areas
Structural connectivity is the
“road map” of fibers connecting different areas of the brain
Functional connectivity
is the neural activity associated with a particular function that is flowing through this structural network
Electroencephalography (EEG)
Measures electrical activity via electrodes
Can be Inter- or Intra-cranial
Electrodes either on or in the skull
Very good time resolution
Milliseconds
Computerized Tomography (CT or CAT)
Builds a picture of the brain based on the differential absorption of X-rays
Reveals gross features of the brain
Does not resolve brain structure well
Functional Magnetic Resonance Imaging (fMRI)
Detects changes in blood oxygenation, blood flow
Tied to neural activity
High activity = high oxygen use and high blood flow
Diffusion Tensor Imaging (DTI)
Builds a picture of water movement in the brain using an MRI scanner
Observe blood flow along specific neural tracts
High spatial resolution and directionality
Near Infrared Spectroscopy (NIRS)
Measures changes in blood oxygenation
Shines near IR light through the skull
Detects attenuation of reemerging light
Indirect measure of brain activity
Connections Between Brain Areas
1- Structural connectivity
2- Functional connectivity
