Neurotransmitters and Synapses
More than one pre-synaptic neuron can form a synapse with the same post-synaptic neuron, meaning that an impulse can be carried from several neurons to one neuron. Usually, neurotransmitter must be repeatedly released, or several neurons must release neurotransmitters to trigger an action potential. This additive effect of neurotransmitter is called summation. Also, some neurotransmitters act as inhibitors.
Psychoactive drugs affect the brain by altering the function of such synapses. Some are excitatory, which increase post-synaptic transmission, whereas others are inhibitory, which decrease post-synaptic transmission.
- Tetrahydrocannabinol (THC)