Receptive Fields and Neurons

Neuron

The basic unit of the nervous system.

Nucleus

contains DNA, controls protein synthesis

Cell Body

The main part of the neuron.

Dendrites

Branch-like extensions of a neuron that receive signals from other neurons

Axon

A long projection of a neuron that carries an action potential away from the cell body

Axon Terminals

The end of the axon where neurotransmitters are released

Myelin Sheath

A fatty covering around the axon that insulates it and speeds up the transmission of action potentials

Nodes of Ranvier

gaps in myelin where signals regenerate

Action Potential

An all-or-nothing electrical signal that travels down the axon of a neuron

Resting Potential

The electrical charge of a neuron when it is not active; typically negative

Ion

A charged atom or molecule

Membrane Potential

The difference in electrical charge across a cell's membrane

Single Cell Recording

A technique used to measure the electrical activity of a single neuron

Refractory Period

a brief period after a neuron fires an action potential in which the neuron cannot fire again

Firing Rate

the number of action potentials per second

Baseline Firing Rate

Spontaneous low-level firing without stimulus

Synapse

the gap between neurons where neurons communicate

Presynaptic Membrane

The membrane of the neuron that sends the signal

Postsynaptic Membrane

The membrane of the neuron that receives the signal

Synaptic Vesicles

Tiny sacs in the axon terminals that store and release neurotransmitters

Neurotransmitters

The chemicals transmitting signals across synapse

Neuron Doctrine

the principle that perception depends on the combined activity of many specialized neurons, each of which responds to specific aspects of a stimulus

Receptive Field

The region of sensory surface where stimulus alters neuron firing

Center-Surround Receptive Field

The response to light in the center is opposite to the response to light in the surround

On-Center Receptive Field

Cell fires more when center is illuminated; cell fires less when the surrounding is illuminated

Off-Center Receptive Field

Cell fires more when surround is illuminated; cell fires less when the center is illuminated 

Preferred Stimulus

s the specific stimulus that causes a neuron to produce its strongest response, typically measured by a high firing rate

Luminance Contrast

Brightness difference between center and surround

Lateral Inhibition

when a neuron reduces the activity of its neighboring neurons, making the contrast between signals stronger

Spot Detectors

Neurons with a circular center-surround receptive field

Edge Enhancement

The process where the visual system exaggerates the contrast at the boundaries of objects, making edges more prominent

Neural Convergence

Multiple inputs converge onto one neuron.

Excitatory Signals

Signals that increase the likelihood of firing

Inhibitory Signals

Signals that decrease the likelihood of firing

Microelectrode Experiment

The recording from single neurons with fine electrodes.

Bipolar Cells

Neurons in the retina that receive signals from photoreceptors and pass them to retinal ganglion cells.

Horizontal Cells

Neurons that connect photoreceptors and bipolar cells horizontally, helping to create lateral inhibition

Amacrine Cells

Neurons that connect retinal ganglion cells and other amacrine cells, also playing a role in lateral inhibition