These observations were made on some seventy patients with a diagnosis of epilepsy caused by lesions somewhere in the temporal lobe. As a preliminary to the removal of the damaged brain tissue by surgery, various points on the surface of the temporal lobe were stimulated with a gentle electric current. The intensity of the stimulation was approximately the least current needed to excite tingling in the thumb by stimulation of the appropriate motor area. If it be objected that the phenomena resulting from this stimulation are corrupted by the presence of some focal area of gliosis, or sclerosis, or meningo-cerebral cicatrix, all typically found in such patients, I think such objections would be dissipated by reviewing the original report. These abnormalities, when found, were circumscribed in location and were not in any way influencing the responses of the subject as they were being stimulated.9 It can thus be assumed with some confidence that the results of these studies are representative of what would be found in normal individuals.
In the great majority of these cases, it was the right temporal 8 Wilder Penfield and Phanor Perot, "The brain's record of auditory and visual experience: a final summary and discussion," Brain, 1963, 86: 595—702.
9 Though presumably the particular aura of the epilepsy had been occasioned by the spread of cortical excitation from the lesion to these same areas.
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lobe that was stimulated, particularly the posterior part of the temporal lobe toward its superior convolution, Wernicke's area on the right side. A remarkable series of responses from the patients was obtained. This is, to repeat myself, the point at which we might expect to hear the gods of antiquity calling to us again, as if from the other part of our bicameral minds. Would these patients hear some vestiges of the ancient divinities?
Here are some representative data.
When stimulated in this region, Case 7, a twenty-year-old college student, cried out, "Again I hear voices, I sort of lost touch with reality. Humming in my ears and a small feeling like a warning." And when stimulated again, "Voices, the same as before. I was just losing touch with reality again." When asked, he replied that he could not understand what the voices were saying.
They sounded "hazy."
In the majority of cases, the voices were similarly hazy. Case 8, a twenty-six-year-old housewife, stimulated in approximately the same area, said there seemed to be a voice a way, way off. "It sounded like a voice saying words but it was so faint I couldn't get it." Case 12, a twenty-four-year-old woman, stimulated at successive points of the superior gyrus of the posterior temporal lobe, said, "I could hear someone talking, murmuring or something."
And then further on, "There was talking or murmuring, but I cannot understand it." And then stimulated about three quarters of an inch along the gyrus, she was at first silent, and then gave a loud cry. "I heard the voices and then I screamed. I had a feeling all over." And then stimulated a little back toward the first stimulations, she began to sob. "That man's voice again! The only thing I know is that my father frightens me a lot." She did not recognize the voice as her father's; it only reminded her of him.
Some patients heard music, unrecognized melodies that could be hummed to the surgeon (Cases 4 and 5). Others heard relatives, particularly their mothers. Case 32, a twenty-two-year-old
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woman, heard her mother and father talking and singing, and then stimulated on another point, her mother “just yelling.”
Many patients heard the voices as emanating from strange and unknown places. Case 36, a twenty-six-year-old woman, stimulated somewhat anteriorly on the superior gyrus of the right temporal lobe, said, “Yes, I heard voices down along the river somewhere — a man’s voice and a woman’s voice, calling.”
When asked how she could tell it was down along the river, she said, “I think I saw the river.” When asked what river, she said,
“I do not know, it seems to be one I was visiting when I was a child.” And at other stimulation points, she heard voices of people calling from building to building somewhere. And at an adjacent point, the voice of a woman calling in a lumberyard, though she insisted that she had “never been around any lumberyard.”
When the voices were located as coming from one side or the other, as rarely happened, it was from the contralateral side.
Case 29, a twenty-five-year-old man, stimulated in the middle of the right temporal gyrus, said, “Someone telling me in my left ear, ‘Sylvere, Sylvere!’ It could have been my brother.”
The voices and the music, whether garbled or recognized, were experienced as actually heard, and the visual hallucinations were experienced as-actually seen, just as Achilles experienced Thetis, or Moses heard Yahweh out of the burning bush. Case 29, the same as above, when stimulated again, also saw “someone speaking to another and he mentioned the name, but I could not understand it.” And when asked whether he saw the person he replied, “It was just like a dream.” And when asked further if the person was there, he said, “Yes, sir, about where the nurse with the eyeglasses is sitting over there.”
In some slightly older patients, only exploratory stimulation produced an hallucination. A thirty-four-year-old French-Canadian, Case 24, after previous stimulations had produced nothing, when stimulated on the posterior part of the middle gyrus of the
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right temporal lobe, suddenly said, "Wait a minute, I see someone! " And then about an inch higher, "Oui, la, la, la! It was he, he came, that fool!" And then stimulated somewhat higher though still within what corresponds to Wernicke's area on the right side, "There, there, j'entend! It is just that somebody wanted to speak to me, and he was going, 'vite, vite, vite!'
But at younger ages, there is a definite suggestion that hallucinations caused by stimulating the right temporal lobe are more striking, vivid, and admonitory. A fourteen-year-old boy (Case 34) saw two men sitting in armchairs singing at him. A fourteen-year-old girl, Case 15, when stimulated on the superior posterior gyrus of the right temporal lobe, cried out, "Oh, everybody is shouting at me again, make them stop!" The stimulus duration was two seconds; the voices lasted eleven seconds. She explained, "They are yelling at me for doing something wrong, everybody is yelling." At all stimulation points along the posterior temporal lobe of the right hemisphere, she heard yelling. And even when stimulated an inch and a half posterior to the first point, she cried out, "There they go, yelling at me; stop them!"
And the voices coming from just one stimulation lasted twenty-one seconds.
I should not give the impression that it is all this simple. I have selected these cases. In some patients, there was no response at all. Occasionally such experiences involved autoscopic illusions such as we referred to in I.2. A further complication is that stimulation of corresponding points on the left or usually dominant hemisphere may also result in similar hallucinations.
In other words, such phenomena are not confined to the right temporal lobe. But the instances of response to stimulation on the left are much less frequent and occur with less intensity.
The important thing about almost all these stimulation-caused experiences is their otherness, their opposition from the self, rather than the self's own actions or own words. With a few
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exceptions, the patients never experienced eating, talking, sex, running, or playing. In almost all instances, the subject was passive and being acted upon, exactly as a bicameral man was acted upon by his voices.
Being acted upon by what? Penfield and Perot think it is simply past experience, flashbacks to earlier days. They try to explain the failure of recognition so consistently observed as mere forgetfulness. They assume that these were actual specific memories that with more time during the operation could have been pushed into full recognition. In fact, their questions to the patients during stimulation were guided by this hypothesis.