Function<br />Part of the reward circuit.<br />Two neurotransmitters:<br /> dopamine (desire)<br /> seretonin (satiety and inhibition)<br />Maintains motivation.<br />Controls feeding, sexual, reward, stress-related, and drug self-administration behaviours. <br />
A study by James Oldes<br /><ul><li>Aim – to determine how rats would respond to the opportunity of stimulating their pleasure centers by pressing a lever.</li></li></ul><li>Procedure<br />Oldes implanted electrodes in the brains of the rats.<br />They received an electrical shock to their nucleus accumbens each time they pressed a lever.<br />In some conditions, an electrified grid was placed between the rat and the lever.<br />
Results and Findings<br />The rats became addicted to the rush of pushing the lever.<br />They preferred it to eating and drinking – some of the rats even starved themselves.<br />Many even ran across the electrified grid to reach the lever.<br />
A study by Axmacher et al.<br /><ul><li>Aim: to determine whether activation of the nucleus accumbens precedes the formation of memories of surprising events.</li></li></ul><li>Procedure<br />Implanted electrodes in the nucleus accumbens and hippocampus of participants.<br />Showed participants a picture of a face on a red background for a few seconds and then switched the picture to a house on a green background.<br />Used an electroencephalogram (EEG) to put together the overall pattern of brain activity while this was happening.<br />
Results and Findings<br />Switching the stimulus activated the hippocampus, the nucleus accumbens, and then the hippocampus again.<br />This brain pattern provides a way to consistently predict memory formation.<br />The nucleus accumbens is involved in processing not only rewards, but also novel information.<br />May influence further processing by the hippocampus.<br />
Schaepfer et al.<br />Aim: try to treat severely depressed patients who had not responded to alternative treatments using deep brain stimulation.<br />
Procedure<br />Implanted the electrodes in the nucleus accumbens of the patients.<br />Turned on the stimulator to send electrical signals to that part of the brain.<br />Turned the stimulator on and off over a period of weeks and tracked development of symptoms by questionnaires.<br />
Results and Findings<br />Most patients reported positive effects instantaneously – they had newfound motivation.<br />Most patients improved only in the short-term – they had instant results that did not last.<br />Deep brain stimulation of the nucleus accumbens did not treat depression in the long term.<br />
Drug addiction – unusually high levels of dopamine in the nucleus accumbens.</li></li></ul><li>Works Cited<br />Crane, J., & Hannibal, J. (2009). Psychology: Course Companion. Oxford: Oxford University Press.Dubuc, B. (2002, September). The Pleasure Centres Affected by Drugs. In The Brain from Top to Bottom. Retrieved from http://thebrain.mcgill.ca/Fernandez-Espejo, E. (2000, May). How does the Nucleus Accumbens Function? In Pub Med [biomedical data base]. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedHarmon, K. (2010, February 24). Surprised? How the Brain Records Memories of the Unexpected. In The Scientific American. Retrieved from http://www.scientificamerican.com<br />
Works Cited cont.<br />New Way To Fight Cocaine Addiction Discovered. (2009, April 2). Science Daily. Retrieved from University of California - Irvine website: http://www.sciencedaily.com<br />Scientists Discover Alterations in Brain’s Reward System Related to Attention-Deficit/hyperactivity Disorder. (n.d.). Science Daily. Retrieved from Universitat Autònoma de Barcelona website: http://www.sciencedaily.com<br />Singer, E. (2007, April 26). Brain Electrodes Help Treat Depression. In Technology Review. Retrieved from Massachusetts Institute of Technology website: http://technologyreview.com<br />Surprise! Neural Mechanism May Underlie an Enhanced Memory for the Unexpected. (2010, February 25). Science Daily.<br />
A particular slide catching your eye?
Clipping is a handy way to collect important slides you want to go back to later.