On arriving at the presynaptic terminal a chemical neurotransmitter is released altering the electrical property of the postsynaptic neuron; causing excitement and stimulation allowing the message to continue to the next neuron or inhibits its behavior causing the impulse to cease. .
This communication within the cells is electrical but ends as a chemical reaction when the neurotransmitter is released. 'Neurons are characterized by the type of neurotransmitter they store and release' (Toates. 2007) and is dependent on the required behavior and emotion. Neurotransmitters include dopamine, serotonin and acetylcholine. Acetylcholine is found at every junction between a motor neuron and a muscle and released when a muscle contracts. Once the chemical connects with the receptor and has activated the electrical charge, the neurotransmitter is either inactivated by enzymes or by returning it to the pre-synaptic neuron through re-uptake. The electrical impulses will continue its journey from neuron to neuron until the action potential arrives at the spinal cord where the withdrawal reflex will be triggered through the motor neurons, and further transmissions will continue to the brain where the sensation of pain will be emitted. .
Evolution has shaped physical and behavioral characteristics through motivation for survival and reproduction. Behavior is determined through the integration of information from the internal human body and the external environment. Interruption in this communication will change how the synapses work, altering the neuronal patterns of activity and affect behavior, cognition and mood.
