MY INE - Step 4

"The main theme to emerge... is that there appear to be two modes of thinking, verbal and nonverbal, represented rather separately in left and right hemispheres respectively and that our education system, as well as science in general, tends to neglect the nonverbal form of intellect. What it comes down to is that modern society discriminates against the right hemisphere."

-Roger Sperry (1973)

MY INE - Step 3

A longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum. The sides resemble each other and each hemisphere's structure is generally mirrored by the other side. Yet despite the strong similarities, the functions of each cortical hemisphere are different.

Popular psychology tends to make broad and sometimes pseudoscientific generalizations about certain functions (e.g. logic, creativity) being lateral, that is, located in either the right or the left side of the brain. Researchers often criticize popular psychology for this, because the popular lateralizations often are distributed across both hemispheres, [1] although mental processing is divided between them.[citation needed]

Many differences between the hemispheres have been observed, from the gross anatomical level to differences in dendritic structure or neurotransmitter distribution. For example, the lateral sulcus generally is longer in the left hemisphere than in the right hemisphere. However, experimental evidence provides little, if any, consistent support for correlating such structural differences with functional differences. (citation: see, for example Toga & Thompson (2003). Mapping brain asymmetry. Nature Reviews Neuroscience (4). 37-48; http://www.ncbi.nlm.nih.gov/books/bv.fcgi?indexed=google&rid=neurosci.section.1912 The extent of specialized brain function by area remains under investigation. If a specific region of the brain is either injured or destroyed, its functions can sometimes be assumed by a neighboring region, even in the opposite hemisphere, depending upon the area damaged and the patient's age. Injury may also interfere with a pathway from one area to another. In this case, alternative (indirect) connections may exist which can be used to transmit the information to the target area. Such transmission may not be as efficient as the original pathway.

While functions are lateralized, the lateralizations are functional trends, which differ across individuals and specific function. Short of having undergone a hemispherectomy (removal of a cerebral hemisphere), no one is a "left-brain only" or "right-brain only" person.

Brain function lateralization is evident in the phenomena of right- or left-handedness and of right or left ear preference, but a person's preferred hand is not a clear indication of the location of brain function. Although 95% of right-handed people have left-hemisphere dominance for language, only 18.8% of left-handed people have right-hemisphere dominance for language function. Additionally, 19.8% of the left-handed have bilateral language functions.[2] Even within various language functions (e.g., semantics, syntax, prosody), degree (and even hemisphere) of dominance may differ.

(text from wikipedia)

MY INE - Step 2

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