Depression results from a malfunction in the transmission of information from one neuron to another in the brain. Between two neurons, there is an interval, called a synapse, in which the neuron transmitting the information rejects molecules, the neurotransmitters, which are picked up by the neuron receiving the information. The uptake of neurotransmitters by a neuron leads to the generation of an electrical current, the nerve influx, which transits through the axon, the neuron’s extension, to the next synapse and triggers the secretion of neurotransmitters.
Biological Mechanisms of Depression
A disturbance in the production and uptake of 3 major neurotransmitters is responsible for the development of the major depressive episode.
- Serotonin, which balances sleep, appetite and mood
- Dopamine, responsible for regulating mood and motivation
- Noradrenaline Manages Attention and Sleep
These neurotransmitters are present in many areas of the brain. Using functional brain imaging (functional MRI), it is possible to identify the brain areas most involved in depression.
Depression is a disorder affecting the dynamics of brain networks involved in emotional regulation, cognitive control and self-reference.
At Paris Brain Institute
The ANR project “SENSO” coordinated by Professor Philippe FOSSATI has made it possible to define brain imaging markers to facilitate the diagnosis of depression. By functional MRI it was possible to identify a malfunction of a network linking different brain regions. Under normal conditions, the role of this neural network is to determine which external stimulations are of interest.
Among other things, this project has made it possible to highlight the role of the medial prefrontal cortex, which plays a role in sadness and self-devaluation of the self, of the left dorso lateral prefrontal cortex involved in working memory, and of the precursor associated with ruminations. He also emphasized the role of the ventral cingulate cortex in sensitivity to social exclusion signals, a key factor in the onset of a major depressive episode.
