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studies reveal evidence showing that a certain section of the corpus callosum, the selenium, is thicker in women (Levay, 1993 & Nadeau, 1996). Other scientists state that the size of the corpus callosum is the same in men and women, but since women's brains are smaller, the corpus callosum is bigger in relation to the smaller brain size (LeVay, 1993). The anterior commissure, another connection between the two hemispheres is unanimously supported as being larger in women (LeVay, 1993 & Nadeau, 1996). Yet another band of connective tissue, the massa intermedia, has been reported larger in women (Nadeau, 1996). This area connects the left and right halves of the thalamus and is documented as being 53% larger in women. .
Within the hypothalamus lies a region known as the suprachiasmatic nucleus (SCN). This area is involved in the regulation of circadian rhythms and periodic processes, such as the sleep-wake cycle and ovulation (Nadeau, 1996). One source reports that volume and cell number are the same in males and females, but claims the shape is different. In females it is more elongated and in males it is more spherical (Nadeau, 1996). Another study agreed that a shape difference existed, but also stated that the SCN is 43% larger in females (LeVay, 1993). This difference in findings may be due to the significant time and technology gap between the two studies.
Perhaps the greatest amount of dissention comes when overall brain size is discussed. Simon LeVay (1993) states that male brains are 15% larger than those of females on average. However, an article out of Science (1995) states that female brains are only 10% smaller than male brains. This size difference is attributed to a finding that show female brains to have higher neuronal density in certain areas of the brain, as well as having 11% more neurons in the cortex tissue, as found by Sandra Witelson of McMaster University.