Serotonin delivers and regulates signals between neurons. It may be responsible for a variety of both bodily and psychological functions including appetite, memory, sleep, social behavior, mood and sexual functioning. More »

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Physical symptoms of serotonin deficiency include persistent fatigue, sleep disorders, loss of appetite combined with a craving for carbohydrates, headaches and a fluctuating body temperature, according to Progressive He... More »

Physical symptoms of having low serotonin levels are chronic fatigue, hot flashes, migraines, sleep issues and gastrointestinal pain, reports Progressive Health. Emotional symptoms include depression, emotional sensitivi... More »

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According to the ALS Association, amyotrophic lateral sclerosis is a progressive, neurodegenerative disease that destroys motor neurons in the brain and spinal cord, preventing signals from being sent to voluntary muscle... More »

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Afferent neurons carry signals to the brain and spinal cord as sensory data, and efferent neurons send signals from the brain to the muscles, glands and organs of the body in response to sensory input. More »

Motor neurons transmit signals to muscles and glands throughout the body. There are two major types: the somatic motor neurons that control voluntary muscle movements and the autonomic motor neurons that control involunt... More »

During the reflex arc, sensory neurons carry signals from receptors to interneurons in the spinal cord, which send signals to activate muscles via motor neurons without first signalling the brain. This sequence provides ... More »