psychology-health

The Sodium Amytal Test

 A patient is given an injection of sodium amytal into the carotid artery before having brain surgery. The injection allows neurosurgeons to test one side of the brain at a time for language functionality, while the other side is anesthetized. The process is then reversed and the other hemisphere is tested. The test may involve presenting the patient with flash cards to have them identify objects or numerical and alphabetical series. It is known that the left hemisphere is usually dominant for speech, so when the injection anesthetizes the left hemisphere, the patient may lose the ability to speak momentarily. The right hemisphere, makes more mistakes than the left hemisphere for this test (Pinel, 2007, p.445).

Dichotic Listening Test

 The dichotic listening test involves the simultaneous presentation of spoken digits into the ears of the patient. Generally speaking, the left hemisphere is dominant for language, so the memories are stronger of the digits spoken into the right ear. Sometimes, the memories of the numbers spoken to the left ear are stronger, even though the patient has already shown left hemisphere dominance in the sodium amytal test.

Functional Brain Imaging

 Brain activity can be examined with the use of functional magnetic resonance imaging (fMRI) equipment, or positron emission tomography (PET). The patient will engage in an activity such as speaking or reading, and the activity of the section of brain associated with that skill can be seen. If the patient is reading, the images most often indicate more activity in the left hemisphere of the brain (Pinel, 2007, p.445).

Speech Laterality and Handedness

Left hemisphere dominance for speech has also been tested using the speech laterality and handedness technique. It has been found that lesions or damage to the left hemisphere which causes aphasia, affects more right handed people than left handed people. In addition, it was discovered that “that sinestrals are more variable than dextrals with respect to language lateralization”(Pinel, 2007, p.446 ). Aphasia is caused by brain damage and reduces a person’s ability to speak or understand language.

Reference

Pinel, J. P. J. (2007). Basics of biopsychology. Boston, MA: Allyn and Bacon.

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