Sensitization

Sensitization is a non-associative learning process in which repeated administration of a stimulus results in the progressive amplification of a reflex response. In the neurosciences, sensitization is a process that leads to the amplification of neural responses and has been implicated in various phenomena such as addiction, chronic pain, and post-traumatic stress disorder.

Overview

Sensitization is thought to underlie both adaptive and maladaptive learning processes in the organism. In a benign form, it is a way for the organism to detect and respond to environmental stimuli that are potentially harmful. In a pathological form, it may lead to undesirable outcomes such as chronic pain and drug addiction.

Mechanisms

The mechanisms of sensitization involve changes at the cellular level (cellular sensitization) and changes in the function of neural circuits (systems sensitization). Cellular sensitization involves changes in the function of neurons in response to excessive stimulation, such as the increased production of neurotransmitters or the increased sensitivity of receptors. Systems sensitization involves changes in the function of neural circuits, such as the strengthening of synaptic connections between neurons.

Clinical implications

Sensitization has been implicated in a number of clinical conditions, including chronic pain, drug addiction, and post-traumatic stress disorder. In chronic pain, sensitization may lead to an increased sensitivity to pain, known as hyperalgesia. In drug addiction, sensitization may lead to an increased response to drugs, known as drug sensitization. In post-traumatic stress disorder, sensitization may lead to an increased response to stress, known as stress sensitization.

See also

• Habituation
• Long-term potentiation
• Neural plasticity
• Neurotransmitter
• Receptor (biochemistry)