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Figure 2.1  
Diagram of neuron with synapse. Individual nerve cells, or neurons, both send and receive 
cellular signals to and from neighboring neurons, but for the purposes of this diagram 
only one activity is indicated for each cell. Neurotransmitter molecules are released from 
the neuron terminal and move across the gap between the "sending" and "receiving" 
neurons. A signal is transmitted to the receiving neuron when the neurotransmitters have 
bound to the receptor on its surface. The effects of a transmitted signal include:

·      Changing the cell's permeability to ions, such as calcium and potassium.

·      Turning a particular gene on or off.

·      Sending a signal to another neuron.

·      Increasing or decreasing the responsiveness of the cell to other cellular signals.

Those effects can lead to cognitive, behavioral, or physiological changes, depending on which neuronal system is activated.

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