Topic 2: Early Visual Processing Flashcards
(78 cards)
Neuron
the structure that transmits electrical signals in the body
key components are the cell body, dendrites, and the axon or nerve fiber
Cell Body
the part of a neuron that contains the neuron’s metabolic machinery and that receives stimulation from other neurons
Dendrites
nerve processes on the cell body that receive stimulation from other neurons
Axon
the part of the neuron that conducts nerve impulses over distances
also called the nerve fiber
Nerve Fiber
in most sensory neurons, the long part of the neuron that transmits electrical impulses from one point to another
also called the axon
Resting Potential
the difference in change between the inside and the outside of the nerve fiber when the fiber is not conducting electrical signals
most nerve fibers have resting potentials of about -70 mV, which means the inside of the fiber is negative relative to the outside
Action Potential
rapid increase in positive change in a nerve fiber that travels down the fiber
also called the nerve impulse
Propagated Response
a response, such as a nerve impulse, that travels all the way down the nerve fiber without decreasing in amplitude
Refractory Period
the time period of about 1/1000th of a second that a nerve fiber needs to recover from conducting a nerve impulse
no new nerve impulses can be generated in the giber until the refractory period is over
Spontaneous Activity
nerve firing that occurs in the absence of environmental stimulation
Ions
charged molecules
sodium, potassium, and chlorine are the main ions found within nerve fivers and in the liquid that surrounds nerve fibers
Permeability
a property of a membrane that refers to the ability of molecules to pass through it
if permeability to a molecule is high, the molecule can easily pass through the membrane
Depolarization
when the inside of a neuron becomes more positive, as occurs during the initial phases of the action potential
depolarization is often associated with the action of excitatory neurotransmitters
Rising Phase of the Action Potential
in the axon, or nerve fiber, the decrease in negativity from -70 mV to 140 mV (the peak action level) that occurs during the action potential
this increase is caused by an inflow of Na+ ions into the axon
Hyperpolarization
when the inside of a neuron becomes more negative
is often associated with the action of inhibitory neurotransmitters
Falling Phase of the Action Potential
in the axon, or nerve fiber, the increase in negativity from 140 mV back to -70 mV (the resting potential level) that occurs during the action potential
this increase in negativity is associated with the flow of positively charged potassium ions out of the axon
Synapse
a small space between the end of one neuron (the presynaptic neuron) and the cell body of another neuron (the postsynaptic neuron)
Neurotransmitters
a chemical stored in synaptic vesicles that is released in response to a nerve impulse and has an excitatory or inhibitory effect on another neuron
Receptor Sites
small area on the postsynaptic neuron that is sensitive to specific neurontransmitter
Excitatory Response
the response of a nerve fiber in which the firing rate increases
Inhibitory Response
occurs when a neuron’s firing rate decreases due to inhibition from another neuron
Sensory Coding
how neurons represent various characteristics of the environment
Specificity Coding
type of neural code in which different perceptions are signaled by activity in specific neurons
Grandmother Cell
a highly specific type of neuron that fires in response to a specific stimulus, such as a person’s grandmother
