PSYC 304 - Chapter 3.2

Neurotransmitter

The chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons.

Postsynaptic Potential

A local potential that is initiated by stimulation at a synapse, can vary in amplitude, and spreads passively across the cell membrane, decreasing in strength with time and distance.

Excitatory Postsynaptic Potential (EPSP)

A depolarizing potential in the postsynaptic neuron that is caused by excitatory connections; this increases the probability that the postsynaptic neuron will fire an action potential.

Synaptic Delay

The brief delay between the arrival of an action potential at the axon terminal and the creation of a postsynaptic potential; reflects the time needed for the NT to be released and diffuse across the synapse.

Inhibitory Postsynaptic Potential (IPSP)

A hyperpolarizing potential in the postsynaptic neuron that is caused by inhibitory connections; this decreases the probability that the postsynaptic neuron will fire an action potential.

Chloride Ion (Cl-)

A chlorine atom that carries a negative charge because it has gained one electron.

Spatial Summation

The summation at the axon hillock of postsynaptic potentials from across the cell body. If this summation reaches threshold, an action potential is triggered.

Temporal Summation

The summation of postsynaptic potentials that reach the axon hillock at different times. The closer in time the potentials occur, the more complete the summation.