The brain operates the central nervous system and is the center for motor, arousal, sensory and neuro transmission within the body. Brain activity changes according to the internal and external stimuli that is transmitted to it through the neurons. Certain stimuli affect brain activity significantly more than others, whilst other stimuli affects brain activity negatively.
The ingestion or exposure to particular drugs can change brain activity. For example, antidepressants, the drugs prescribed for psychological problems are designed to affect brain activity. Other substances with similar effects on the brain include caffeine, heroin and sedatives affect the speed and frequency of neurotransmitters’ actions. When the drug is administered, the effects may be temporary, but prolonged use of any drug will obviously have long lasting repercussions on brain activity.
Some studies have shown that the disruption of normal sleeping patterns seriously affects brain activity. Brain activity drops with sleep deprivation causing disruption in cognitive and motor functions. Some parts of the brain may increase activity to compensate for lack of sleep and try to keep the brain active, but the reduction of cognitive and motor functions defeats the other parts of the brain which may be attempting to try and perform normally.
Brain activity is also subject to hormones which cause significant alternations. Studies have shown that women treated with the hormone estrogen had an increase in memory function. The menstrual cycle can be used to determine hormone levels in women; research has shown that at different times in the cycle, sexual attraction and mate preference can occur and are partially controlled by brain activity.