Careful psychologic studies disclose a difference between the effects of dominant and nondominant partial (anterior) temporal lobectomy (Milner, 1971). With the former, there is dysnomia and impairment in the learning of material presented through the auditory sense; with the latter, there is impairment in the learning of visually presented material. In addition, about 20 percent of patients who have undergone temporal lobectomy, left or right, show a syndrome similar to that which results from lesions of the prefrontal regions. Perhaps more significant is the observation that the remainder of the cases show little or no defect in personality or behavior.
Disorders of Memory, Emotion, and Behavior
Finally, attention must be drawn to the central role of the temporal lobe, notably its hippocampal and limbic parts, in memory and learning and in the emotional life of the individual. As indicated earlier, these functions and their derangements have been accorded separate chapters. Memory is discussed in Chap. 20 and the neurology of emotion and behavior in Chap. 24.
To summarize, human temporal lobe syndromes include the following:
I. Effects of unilateral disease of the dominant temporal lobe
A. Homonymous contralateral upper quadrantanopia
B. Wernicke aphasia (word deafness; auditory verbal agnosia)
C. Dysnomia or amnesic aphasia
D. Amusia (some types)
E. Visual agnosia
F. Occasionally, amnesic (Korsakoff) syndrome
II. Effects of unilateral disease of the nondominant
A. Homonymous upper quadrantanopia
B. Inability to judge spatial relationships in some cases
C. Impairment in tests of visually presented nonverbal material
D. Agnosia for sounds and some qualities of music
III. Effects of disease of either temporal lobe
A. Auditory, visual, olfactory, and gustatory hallucinations
B. “Dreamy” states with seizure (focal temporal lobe seizure)
C. Emotional and behavioral changes
D. Delirium-confusional states (usually nondominant)
E. Disturbances of time perception
IV. Effects of bilateral disease
A. Korsakoff amnesic defect (hippocampal formations)
B. Apathy and placidity
C. Klüver-Bucy syndrome: compulsion to attend to all visual stimuli, hyperorality, hypersexuality, blunted emotional reactivity; the full syndrome is rarely seen in humans