till what extent does the drugs affect the neurons?
Psychoactive drugs alter communication between brain cells. Individual brain cells (neurons) communicate with one another through a series of biological messengers called neurotransmitters. These neurotransmitters are released from the neuron sending the message and bind to receptors on the neuron receiving the message.
Some psychoactive substances are able to mimic the effects of neurotransmitters. Others interfere with normal brain function by blocking it, or by altering the way neurotransmitters are stored, released, and removed.