Hockenbury Discovering Psychology 5th txtbk

The Neuron53implicated in the activation of neurons throughout the brain and helps the bodygear up in the face of danger or threat. Norepinephrine also plays a key role in theregulation of sleep, learning, and memory retrieval (McCarley, 2007). Like serotoninand dopamine, norepinephrine dysfunction in implicated in some mental disorders,especially depression (Robinson, 2007).GABA is the abbreviation for gamma-aminobutyric acid, a neurotransmitterfound primarily in the brain. GABA usually communicates an inhibitory message toother neurons, helping to balance and offset excitatory messages. For normal functioning,GABA must be finely balanced. Like a dimmer switch, GABA regulates excitationin the brain. Too much GABA impairs learning, motivation, and movement,but too little GABA can lead to seizures (McCarthy, 2007). Alcohol makespeople feel relaxed and less inhibited partly by increasing GABA activity, which reducesbrain activity. Antianxiety medications, such as Valium and Xanax, also workby increasing GABA activity, which inhibits action potentials.Dopamine and Parkinson’s Disease Boxinglegend Muhammad Ali fakes a swing atactor Michael J. Fox before they both testifiedat a Congressional hearing on Parkinson’sdisease. Parkinson’s disease affectsapproximately 1.5 million Americans, withan estimated 60,000 new cases diagnosedeach year. Parkinson’s disease usually affectsolder adults, but Fox was diagnosedwith Parkinson’s at the age of 30. MuhammadAli has Parkinson’s syndrome, a relateddisease thought to be caused bybrain damage he suffered from years ofprofessional boxing. Caused by the degenerationof dopamine-producing neurons,Parkinson’s symptoms include uncontrollabletrembling, rigid or stiff muscles, impairedbalance, and movement and speechdifficulties. To help ease their symptoms,both Ali and Fox take medications containingL-dopa, which temporarily increasesbrain levels of dopamine. Fox’s foundationhas raised over $50 million for Parkinson’sresearch. Intel founder Andy Grove hasjoined this effort, donating millions of hispersonal fortune to support Parkinson’sresearch after he too was diagnosed withthe disease (Dolan, 2008).Endorphins: Regulating the Perception of PainIn 1973, researchers Candace Pert and Solomon Snyder of Johns Hopkins Universitymade the startling discovery that the brain contains receptor sites that are specificfor the group of painkilling drugs called opiates (Pert & Snyder, 1973). Opiatesinclude morphine, heroin, and codeine, all derived from the opium poppy. Inaddition to alleviating pain, opiates often produce a state of euphoria. Why wouldthe brain have receptor sites for specific drugs like morphine? Pert, Snyder, andother researchers concluded that the brain must manufacture its own painkillers,morphinelike chemicals that act as neurotransmitters.Within a few years, researchers identified a number of such chemicals manufacturedby the brain (Snyder, 1984). Collectively, they are called endorphins, a termderived from the phrase endogenous morphines. (The word endogenous means “producedinternally in the body.”) Although chemically similar to morphine, endorphinsare 100 times more potent. Today, it is known that endorphins are released inresponse to stress or trauma and that they reduce the perception of pain.Researchers have found that endorphins are implicated in the pain-reducingeffects of acupuncture, an ancient Chinese medical technique that involves insertingneedles at various locations in the body (Ulett & Han, 2002; Kemmer, 2007).Endorphins are also associated with positive mood. For example, the “runner’shigh” associated with aerobic exercise has been attributed to endorphins, a topicthat is examined in the Focus on Neuroscience, “Is ‘Runner’s High’ an EndorphinRush?” on the next page.acetylcholine(uh-seet-ull-KO-leen) Neurotransmitter thatcauses muscle contractions and is involvedlearning and memory.dopamine(DOPE-uh-meen) Neurotransmitter involved inthe regulation of bodily movement, thoughtprocesses, and rewarding sensations.serotonin(ser-ah-TONE-in) Neurotransmitter involvedin sensory perceptions, sleep, and emotions.norepinephrine(nor-ep-in-EF-rin) Neurotransmitter involvedin learning, memory, and regulation ofsleep; also a hormone manufactured byadrenal glands.GABA (gamma-aminobutyric acid)Neurotransmitter that usually communicatesan inhibitory message.endorphins(en-DORF-ins) Neurotransmitters thatregulate pain perceptions.