Those laboratory mice have been at it again. This time, we discover that when mice stop drinking moderate levels of alcohol they can become depressed around two weeks later. Mice are commonly used to model the effects of a number of conditions associated with human behavior. But how do we know when a mouse is depressed?
According to Clyde W.Hodge, Ph.D., professor of psychiatry and pharmacology at the UNC School of Medicine, the answer is found in the Porsolt Swim Test. Mice are very good swimmers, so placing them in water for six minutes presents no difficulty. The amount of time a mouse spends immobile is used as the measure for despair or depression. The longer a mouse floats, the more depressed it is considered to be.
According to Hodge, depression in mice is associated with a marked reduction in neural stem cells within the hippocampus region of the brain. Extending the model to humans, Hodge says:
" . . . people who drink moderate amounts of alcohol s...
Definition Sensorineural deafness is hearing loss that occurs from damage to the inner ear, the nerve that runs from the ear to the brain (auditory nerve), or the brain. Alternative Names Nerve deafness; Hearing loss - sensorineural; Acquired hearing loss; SNHL; Noise-induced hearing loss; NIHL Considerations Symptoms may include: Certain sounds seem too loud Difficulty following conversations when two or more people are talking Difficulty hearing in noisy areas Easier to hear men's voices than women's voices Hard to tell high-pitched sounds (such as "s" or "th") from one another Other people's voices sound mumbled or slurred Problems hearing when there is background noise Other symptoms include: Feeling of being off-balance or dizzy (more common with Meniere's disease and acoustic neuromas ) Ringing or buzzing sound in the ears ( tinnitus ) Common Causes The inner part of the ear contains tiny hair cells (nerve endings), which change sounds into electric signals. The nerves then carry these signals to t...
It is time to retire the idea that depression is caused by a “chemical imbalance of the brain.” The chemical imbalance myth creates the false impression that our brains are some form of neurotransmitter porridge that can be rendered just right with squirts of serotonin and dopamine.
Thanks to at least two decades of research, we now have a number of good working models on what tends to go wrong in the brain during a depressive episode. A review article by Murali Rao and Julie Alderson in this month”s Current Psychiatry outlines four overlapping theories of depression. Let’s look at three of them:
Differences in neuron densities in various regions of the brain.
The effect of stress on neural growth and death.
Alterations in feedback pathways connecting the pre-frontal cortex to the limbic system.
The common denominator is what happens when the brain is exposed to chronic stress. Among other things, stress promotes the release of glucocorticoids. O...
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