Lesions To The Left Convexity Patient Who Loses Her Thoughts3

Mrs. M was a patient who sustained a hemorrhage in the midtemporal area of the left hemisphere. Initially, when Mrs. M awoke in hospital, she showed the classic features

3See Kaplan-Solms and Solms (2000, pp. 90-115) for a detailed description of this case, or Turnbull et al. (in press a) more a quantitative investigation of the emotional state of this patient.

of a Wernicke's aphasia4: feeling as though everyone was speaking a strange, unfamiliar language that she could not understand, where in fact she had a deficit of language comprehension ability. The cognitive basis of such disorders is comprehensively covered in any basic neuropsychology text (e.g., Kolb and Wishaw, 1990; McCarthy and Warrington, 1990). In essence it appears to involve a disruption to the system that differentiates the perception of phonemes (e.g., p vs b) from each other. This ability forms the basic foundation of all (auditory) language comprehension; its loss makes familiar speech sound as unintelligible as a foreign language.

Mrs. M momentarily feared that she might be in heaven, especially as she began to recall what had happened to her. However, she rapidly made better sense of her environment. Although she could not understand what anyone said to her, it was evident from the appearance and behavior of the people around her (nurses, doctors, and other patients) that she was in a hospital. Mrs. M's phonemic hearing soon recovered, and she began to comprehend what was said to her, so long as people spoke in short sentences. She was now suffering from a residual disorder of audio-verbal short-term memory, causing, in Luria's (1973) terminology, an acoustico-mnestic aphasia (again, for more detail see the short-term memory sections of any basic neuropsychology text). As a result, she was unable to hold in mind anything that people said to her for more than a brief moment.

This was associated with a curious subjective state. Mrs. M kept "losing" her thoughts. A thought would occur to her, but before she was able to do anything with it, it was gone. Just as she was unable to hold on to what other people said to her, so too she was unable to retain what she "said" to herself. It was as if her memorial consciousness had become a sieve. The same thing happened when she tried to converse with other people. She would formulate the words that she wanted to say, but before she could utter them they had vanished, leaving her speechless and confused.

The severity of this condition fluctuated. Occasionally, Mrs. M noticed that her whole mind had gone "blank"—all her thoughts were lost—not just those related to things she had heard or wanted to say. This state of mind, in which she could not think consciously of anything, was understandably frightening and embarrassing. She responded by retiring to bed and waiting for her thoughts to "come back", which they typically did after several weeks and months. When Mrs. M was at home during weekends, she would frequently withdraw from social interactions and sit privately in her bedroom, waiting for her "mind to come back," as she put it.

In cognitive terms it is understandable that her thoughts would disappear in this way. This patient sustained damage to the midtemporal region of the left hemisphere—a region responsible for holding strings of words (or other audio-verbal sounds) in short-term (or immediate) memory. Damage to this system not only affects the ability to hold in mind the words that one hears but also the words that one generates in one's own consciousness. This is because the same audio-verbal "buffer" is used for words that are generated internally as for words that are externally perceived. Since

4For those unfamiliar with neuroanatomical and neuropsychological terminology, a glossary is available in Turnbull (2002).

the patient's audio-verbal system could not retain her internally generated thoughts in working memory, these thoughts would disappear. In passing, it is of some note that this seems to confirm Freud's proposal (and that of many others) that we communicate our thoughts to our conscious selves by clothing them in words.

What of Mrs. M's psychiatric status? Did she develop a set of psychotic delusions? As suggested above, she did not. There is abundant evidence that her ego functions were fundamentally intact: Despite her difficulties, her behavior continued to be governed by rational and reality-based thinking. For example, she tested her (momentary) delusional belief that she was in heaven against the evidence of her external perception, and this mental work resulted in the subordination of her fantasies to realistic perceptions. Similarly, when she lost her thoughts, she was rational enough to retire to her bedroom, waiting for her mind to return—a perfectly sensible solution to the problem. Clearly, this patient had not really lost her mind; all she had lost was the capacity to represent (or retain) her thoughts in extended consciousness. Her mind (her ego, and superego, see Kaplan-Solms and Solms, 2000) continued to exist and continued to govern her behavior unconsciously. She had lost only a highly specific aspect of ego functioning that lies far from the core of personality.

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