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Unformatted text preview: f a brain, children manage to do so because the half that remains takes over many of the functions of the half that was removed. Weakness on the side opposite the operation will continue, however.” http://www.epilepsyfoundation.org/answerplace/Medical/treatment/surgery/benefitsrisks 33 33 .cfm Split Brains: A House Divided Hemisphere of brain sometimes taken out to treat severe epilepsy Picture taken from: http://www.clevelandclinic.org/neuroscience/treat/epilepsy/surgery/procedures/hemispherectomy.htm http://curiosity.discovery.com/question/importanc e­action­potentials­synapses 34 34 Issue in Brain Research – Are There Sex Differences in the Brain? 35 35 Are There “His” & “Hers” Brains? Sex differences in the brain have been studied for many years. ♂ Reliable differences have been found in activity of certain brain areas during some tasks Many findings seem to reflect cultural bias, and change with cultural changes Example: MRI of language task, right ♀ http://curiosity.discovery.com/quest ion/importance­action­potentials­ synapses 36 36 Consciousness: Body Rhythms and Mental States 37 37 Biological Rhythms and Tides of Experience 38 38 Biological Rhythms A biological clock in our brains governs the waxing and waning of hormone levels, urine volume, blood pressure, and the responsiveness of brain cells to stimulation. Many of these rhythms continue to occur even in the absence of external time cues; they are generated from within. 39 39 Circadian Rhythms Biological rhythms that occur approximately every 24 hours. Best­known circadian rhythm is the sleep­ wake cycle, but there are hundreds of others. 40 40 The Body's Clock Circadian rhythms are controlled by a biological clock, or overall coordinator. The clock is located in a tiny teardrop­ shaped cluster of cells in the hypothalamus called the suprachiasmatic nucleus (SCN). Neural pathways from special receptors in the back of the eye transmit information to the SCN and allow it to respond to changes in light and dark. 41 41 The Body's Clock The SCN then sends out messages that cause the brain and body to adapt to these changes. Other clocks also exist and some may operate independently of the SCN. For most circadian rhythms, the SCN is regarded as the master pacemaker. 42 42 When the Clock Is Out of Sync Under normal conditions, the rhythms are synchronized, just as wristwatches can be synchronized. Their peaks may occur at different times, but they occur in phase with one another. If you know when one rhythm peaks, you can predict when another will do so. 43 43 When the Clock Is Out of Sync When your normal routine changes, your circadian rhythms may be thrown out of phase with one another. Such internal desynchronization often occurs when people take airplane flights across several time zones (jetlag). Sleep and wake patterns usually adjust quickly, but temperature and hormone cycles can take several days to return to normal. 44 44 Moods and Long­term Rhythms In human beings, long­term cycles have been observed in everything from the threshold for tooth pain to conception rates. Folklore holds that our moods follow similar rhythms, particularly in response to seasonal changes and, in women, to menstrual changes. But do they? 45 45 Does the Menstrual Cycle Affect Moods? Controversy has raged about one well­ known long­term rhythm, the monthly female menstrual cycle. 46 46 Does the Season Affect Moods? Clinicians report that some people become depressed every winter, when periods of daylight are short, and improve in mood each spring, as daylight increases This pattern that has come to be known as seasonal affective disorder (SAD) The actual incidence is rare – less than 1% lifetime prevalence in the U.S. 47 47 Does Testosterone Affect Moods The notion that hormones affect mood and performance has rarely been extended to men. Men’s hormones also fluctuate in a cyclical manner. There may be a bias to attribute women’s moods to hormones, but not men’s Little work has been done on men’s mood/ testosterone fluctuations 48 48 Questions? 49 49...
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This note was uploaded on 10/03/2013 for the course SOCI 1000 taught by Professor Tim during the Fall '13 term at CUHK.

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