|The systems which combine to make atoms. Once thought to be merely
electrons, protons and neutrons, it is now recognized that these subatomic particles are
highly complex, possessing properties of both matter and electromagnetic waves.
Naturally occurring background radiation is a part of our environment. This radiation is from a combination of cosmic rays and radon gas from the earth. Man-made sources of ionizing radiation include radionucleotides in tobacco smoke* and a number of medical, industrial and military uses.
Ionizing radiation breaks the chemical bonds that hold molecules together. Of particular concern is the injury caused to DNA. More highly exposed populations have included survivors of Hiroshima and Nagasaki, uranium miners, residents near the Nevada test site (1951-63) and Chernobyl victims.
Subatomic treatment approaches, used to treat depression, include electroconvulsive therapy, transcranial magnetic stimulation, photon (light) therapy, and some research involving a negative ion generator.*
Atoms bond to form molecules. When atoms lose or gain electrons in their outer shell, they become ions. Sodium, potassium and chloride ions are some of the many ions present in the body.
Ions play a significant role in neural functioning. There is a greater ratio of potassium to sodium within a cell. During nerve activity, an action potential occurs which is associated with a shift in sodium and potassium. Receptor sites control the flow of ions through ion channels across the cell membrane.
Calcium channels are significant in nerve functioning. The functioning of these channels are modulated by ions such as magnesium, zinc and neurotransmitters.
Calcium ions appear to play a role in short-term memory. Calcium ions are increased in the sending neuron prior to the release of the neurotransmitter. The elevated levels of calcium persists for tens of seconds after triggering the neurotransmitter and these elevations can enhance subsequent responses between neurons.*
In a number of pathological states there is an excessive activity of the neuron, causing an excessive flow of calcium into the cell. This activates enzymes, which increase free radicals causing cell death by excitotoxicity. The cell is literally stimulated to death.*
Lithium is an ion with well-proven psychoactive effects. Many of the ancient healing springs, where miracles have been said to occur, were lithium springs.
Basic molecules, such as water and ammonia are both in our body and our environment. Recently, there has been recognition that carbon monoxide and nitric oxide are important mediators of neural functioning.
Organic molecules, such as amino acids, are the basic building blocks of life.
Most of the neurotransmitters, such as serotonin, are organic molecules. New neurotransmitters and sub-types are constantly being discovered. Serotonin-releasing neurons are part of the serotonin system and account for a relatively small part of the brain in the raphe nucleus. One cell in the serotonin system can modulate the functioning of hundreds of thousands of other neurons.
High serotonin in lower life forms, such as the lobster, is associated with increased muscle tone. In more advanced life forms, serotonin modulates a multitude of other functions. From the standpoint of mental functioning, elevated serotonin is associated with projection into the environment. Conversely, low serotonin is associated with a state of retreating from the environment.
Norepinephrine is associated with higher levels of emotional arousal. The center of norepinephrine functioning is the locus coeruleus in the brain stem. Norepinephrine release effects distant neurons in a manner that can be equated to the release of an aerosol spray can.
When norepinephrine activity is high, there is increased activity in the limbic system and decreased activity in the cerebral cortex resulting in performance anxiety.
Dopamine activity is centered in the nucleus acumbens. In a healthy state, the normal pleasures of life are associated with dopamine release. Low dopamine is associated with states of boredom and anhedonia (an inability to appreciate pleasure). Drug addiction is associated with a failure of normal dopamine functioning.
Corticotrophin releasing hormone is a hormone that mobilizes the body to modulate into the stress response mode of functioning.
The body can tolerate episodic states of acute stress. Chronic stress correlates with chronically elevated levels of CRH and norepinephrine and has a pathological effect on sensitive areas of the brain, such as the hippocampus, causing atrophy of this region. Some investigative treatments are aimed at impacting CRH.
All four of these neuromodulators are altered in a state of depression.