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Interhemispheric Transfer Deficit in Alexithymia: An Experimental Study

From the Department of Psychology, Trent University, Peterborough, Ontario (J.D.A.P, M.L.K., C.T.S.), and Department of Psychiatry, University of Toronto and Mount Sinai Hospital, Toronto, Ontario (G.J.T), Canada.

Address reprint requests to: James D. A. Parker, PhD, Department of Psychology, Trent University, Peterborough, Ontario, Canada, K9J7B8. Email: jparker{at}trentu.ca

	ABSTRACT

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OBJECTIVE: Previous research has demonstrated an association between alexithymia and a deficit in interhemispheric communication in Vietnam combat veterans with posttraumatic stress disorder. The purpose of this study was to evaluate this association in a nonclinical sample.

METHODS: The efficiency of interhemispheric transfer was assessed in 14 alexithymic and 15 nonalexithymic right-handed, male, undergraduate university students using a tactile finger localization task.

RESULTS: The nonalexithymic subjects were significantly more efficient at transferring information between the cerebral hemispheres than the alexithymic subjects.

CONCLUSIONS: This finding provides further evidence of an interhemispheric transfer deficit in alexithymia and suggests that an alexithymic cognitive style reflects poor integration of the information processing of the two cerebral hemispheres.

Key Words: alexithymia • functional commissurotomy • interhemispheric transfer

Abbreviations: MSE = mean square error; SD = standard deviation; TAS = Toronto Alexithymia Scale; TAS-20 = 20-item TorontoAlexithymia Scale.

	INTRODUCTION

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The alexithymia construct encompasses the following salient features: difficulty identifying and describing feelings; difficulty distinguishing between feelings and the bodily sensations of emotional arousal; constricted imaginal processes, as evidenced by a paucity of fantasies; and a cognitive style that is concrete and externally oriented (1, 2). Although interest in alexithymia has focused primarily on examining the association between this personality construct and a variety of medical and psychiatric disorders (2), a small number of investigators have explored underlying neurobiological processes.

More than two decades ago, cerebral laterality researchers demonstrated that the left cerebral hemisphere in right-handed individuals displays an advantage for verbal and analytical functions and that the right hemisphere is at an advantage for a nonverbal spatial and holistic mode of processing, including imagery and the perception and nonverbal expression of emotion (3). This discovery led Hoppe and Bogen (4) to predict that "split-brain" patients (ie, patients who had undergone cerebral commissurotomies for treatment of intractable epilepsy) should manifest some features of alexithymia. In a preliminary investigation of 12 split-brain individuals, Hoppe and Bogen (4) observed a paucity of fantasies, difficulty in describing feelings, and a pronounced operative style of thinking. Buchanan et al. (5) subsequently reported a similar cluster of alexithymic characteristics in a 37-year-old man with agenesis of the corpus callosum. On the basis of these findings in split-brain patients, Hoppe (6) postulated that alexithymia might involve an interruption of the normal flow of information between the two cerebral hemispheres; he referred to this as a "functional commissurotomy."

Support for this hypothesis has come from experimental research with both split-brain patients and neurologically intact individuals. Using a complex method of content analysis to assess emotional expressiveness and the quality of fantasy and symbolization, TenHouten et al. (7) compared the spoken and written responses of eight patients who had had cerebral commissurotomies (six complete and two partial) with those of eight neurologically intact control subjects to a film that was aimed at evoking emotions and fantasies by symbolically representing death and loss. The results showed that the split-brain patients were more alexithymic than the control subjects.

Additional support for the interhemispheric communication deficit hypothesis of alexithymia was provided by Zeitlin et al. (8), who used a tactile finger localization task to assess the efficiency of interhemispheric communication. This task requires participants to respond, while blindfolded, to fingers touched in sequence by an examiner. Participants respond to one-, two-, three-, or four-finger sequences by touching the fingers that have been touched with the thumb of the same hand (uncrossed condition) or by touching the corresponding fingers on the other hand with the thumb of that hand (crossed condition). The task provides a behavioral measure of interhemispheric transfer because the condition in which one hand receives the stimulus and the other hand is required to respond (crossed condition) requires the transfer of information across the corpus callosum for successful performance. For normal adults, the crossed condition is only slightly more difficult than the uncrossed condition of this task (9). It has been shown, however, that split-brain patients and individuals with agenesis of the corpus callosum perform extremely poorly on the crossed condition of the task (9, 10); moreover, the greater the extent of the surgical section of the corpus callosum in split-brain patients, the more severe the loss in cross-localization accuracy (9). Zeitlin et al. (8) found that alexithymic male Vietnam combat veterans with posttraumatic stress disorder displayed a significant deficit in the interhemispheric transfer of sensorimotor information when compared with nonalexithymic veterans and with normal control subjects. In addition, the deficit in interhemispheric transfer was bidirectional.

In a later study, Dewaraja and Sasaki (11) used a different methodology to explore the relationship between interhemispheric transfer and alexithymia. On the basis of scores on the Schalling-Sifneos personality scale, right-handed university students were identified as either alexithymic or nonalexithymic and were then given a series of lateralized visual matching tasks (using a tachistoscope) that involved linguistic or nonlinguistic stimuli. Differences in ipsilateral or contralateral hand reaction times were used to indicate speed of callosal transfer. The alexithymic group was significantly slower than the nonalexithymic group in the callosal transfer of nonlinguistic information, but the groups did not differ in the speed of transferring linguistic information. In contrast to Zeitlin et al.’s (8) finding of a bidirectional relationship between alexithymia and the callosal transfer process, Dewaraja and Sasaki (11) found only a right-to-left relationship.

Although the results from the two studies with neurologically intact individuals support the hypothesis of an interhemispheric transfer deficit in alexithymia, the use of combat veterans with posttraumatic stress disorder in Zeitlin et al.’s (8) study raises questions about the generalizability of the findings to other populations, and the study by Dewaraja and Sasaki (11) is limited by the use of the Schalling-Sifneos personality scale to measure alexithymia because the scale lacks reliability and validity (2).

The purpose of the present study was to determine whether the findings from the Zeitlin et al. (8) study could be replicated in a nonclinical sample.

	METHODS

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Subjects and Measures
The sample consisted of 29 right-handed male volunteers selected from two large undergraduate psychology classes on the basis of gender, response to an inquiry about their handedness, and alexithymia scores. Exclusion criteria included individuals who were being treated for psychiatric problems or were taking psychotropic medications. Female students and left-handed male students were excluded as participants because of reports in the literature that there is a lesser degree of cerebral lateralization in these groups (12, 13). All male students in the psychology classes who identified themselves as right-handed (N = 141) were prescreened for alexithymia with the TAS-20 (2, 14), which is a revised and improved version of TAS, which was used in Zeitlin et al.’s study (8). Although both scales are highly correlated and demonstrate both internal reliability and test–retest reliability (2, 14), TAS-20 has a more stable factor structure than the TAS because of the addition of several new items and the elimination of items found to have low-magnitude corrected item/total correlations, high correlations with a social desirability scale, or significant loadings on more than one factor (2, 14). In the process of improving the psychometric properties of the scale, all items assessing fantasy activity were eliminated; it has been demonstrated, however, that the facet of the alexithymia construct pertaining to constricted imaginal activity is assessed indirectly by the factor assessing externally oriented thinking (2, 15). Like TAS, TAS-20 has empirically derived cutoff scores for identifying alexithymic and nonalexithymic groups (2).

Among the 29 right-handed male students, 14 scored in the alexithymic range (61), and 15 students scored in the nonalexithymic range (51) on TAS-20. The alexithymic group had a mean TAS-20 score of 66.79 (SD = 5.47) and a mean age of 21.00 years (SD = 1.54). The nonalexithymic group had a mean TAS-20 score of 37.00 (SD = 9.14) and a mean age of 23.36 years (SD = 7.66). The handedness of the 29 subjects was further assessed with the 13-item General Laterality Scale taken from the Lateral Preference Schedule (16). No subject scored more than 34, confirming that all subjects were right-handed. None of the 29 subjects refused to participate in the experiment; they all gave informed consent and received either course credit or $5 for volunteering to participate in the study.

Procedure
For each subject, the efficiency of interhemispheric communication was assessed with the tactile finger localization task, which was administered in the same manner as used in the study by Zeitlin et al. (8). This task was standardized by Geffen et al. (9, 17) and is considered a reliable and valid procedure for assessing the efficiency of interhemispheric transfer of information (17, 18). As noted earlier, an inability to perform crossed tactile localization has been demonstrated as an effect of callosal agenesis or surgical disconnection of the commissures (9, 10).

The subject was seated at a table on which he rested his forearms stretched in front of him with the palms up. After having the tactile finger localization task demonstrated until he understood how to perform and respond, the subject was blindfolded. The examiner, who was blinded to TAS-20 scores for all subjects, then lightly touched the tip of one, two, three, or four of the subject’s fingers sequentially with the sharpened point of a pencil in a random order identical for each subject. In each trial, after the fingers were stimulated, the subject was asked to indicate which fingers had been touched by touching the same fingers with the tip of the thumb of the same hand (uncrossed condition) or the corresponding fingers on the opposite hand with the thumb of that (opposite) hand (crossed condition). The subject was told which hand would be stimulated, how many fingers would be touched, and with which hand to respond before each trial. No feedback concerning the accuracy of response was provided in any trial. No information was collected on the speed of response, but the subject was instructed to respond as quickly as possible. A 5-minute rest period was given to the subject halfway through the procedure.

Each subject was tested for localization and transfer of one-, two-, three-, and four-finger sequences. There were eight conditions administered in the following order: one-finger localization uncrossed (same hand responding), one-finger localization crossed (opposite hand responding), two-finger localization uncrossed, two-finger localization crossed, etc. There were 40 trials per condition and 20 trials per hand (320 trials total). Fifteen subjects were randomly assigned to start with the right hand, and 14 started with the left hand. Within each two-, three-, and four-finger trial, each finger was stimulated only once. For a trial to be scored as correct, subjects had to touch the correct fingers in the same order as stimulated. The total number of correct responses for each hand was recorded by the examiner. Order effects were not evaluated because each subject completed the various trials in the same order.

Kuder-Richardson internal reliabilities were calculated for the various two-, three-, and four-finger trials (left-hand presentation and left-hand response, left-hand presentation and right-hand response, right-hand presentation and right-hand response, and right-hand presentation and left-hand response). Alpha coefficients could not be calculated for the one-finger trials because of limited variability on many trials. Across the two-, three-, and four-finger trials, alpha coefficients ranged from 0.68 to 0.92, suggesting that the task had acceptable internal reliability.

	RESULTS

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A group (alexithymic vs. nonalexithymic) by presentation hand (left vs. right) by response hand (same as presentation hand vs. opposite hand) analysis of variance was conducted with the number of correct responses on the tactile finger localization task as the dependent variable. Means and SDs for the alexithymic and nonalexithymic groups on each condition of the tactile finger localization task are presented in Table 1.

There was also a significant main effect for response hand (F(1,27) = 40.92, p < .001, MSE = 18.18), indicating that for both the alexithymic and nonalexithymic groups, performance was significantly better when the response hand was the same as the presentation hand (uncrossed condition). The main effect for presentation hand was not significant (p > .05). A significant interaction between group and response hand was found (F(1,27) = 6.17, p < .05, MSE = 6.17) and is depicted graphically in Figure 1.

View larger version (17K): [in this window] [in a new window]   Fig. 1. Effect of the two groups by response hand on number of correct responses on the tactile finger localization task. Nonalexithymic group (——); alexithymic group (- - -- - -).

Planned comparisons using contrast coefficients were also calculated to determine whether the interhemispheric deficit observed in the alexithymic group was bidirectional or unidirectional. A significant difference was found for the alexithymic group when they were required to transfer the task information from the left hemisphere to the right (F(1,27) = 24.79, p < .001, MSE = 12.46) as well as from the right hemisphere to the left (F(1,27) = 32.45, p < .001, MSE = 11.90), indicating that the effect is bidirectional. No significant differences were found between the uncrossed conditions in the alexithymic group (left presentation and response hand vs. right presentation and response hand; p > .05).

	DISCUSSION

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The results of this study are consistent with the findings reported by Zeitlin et al. (8) and provide additional support for alexithymia being associated with a deficit in interhemispheric transfer. Alexithymic individuals made significantly more response errors than nonalexithymic individuals on the crossed component of the tactile finger localization task. This difference was found for transfer from right to left hemisphere and from left to right hemisphere, indicating that the interhemispheric transfer deficit is bidirectional.

The finding that alexithymic and nonalexithymic groups performed equally well on the uncrossed component of the task suggests that the deficit is specific to interhemispheric transfer and not due to alexithymic individuals performing poorly, in general, on neuropsychological tasks. Additional studies are needed, however, to evaluate the performance of alexithymic individuals on a variety of neuropsychological tasks.

The finding that the alexithymic subjects showed no difference between left-hand and right-hand performance in the uncrossed condition indicates that the interhemispheric transfer deficit is not due to a dysfunction in one or the other hemisphere. This finding, however, does not exclude the possibility that alexithymic individuals might manifest other information-processing deficits that are associated with dysfunction in a particular hemisphere. Indeed, several studies have found alexithymia to be associated with a diminished ability to recognize posed facial expressions of basic emotions (19–21), an ability that is linked predominantly to the right cerebral hemisphere (22).

Although it is well-established that the right and left hemispheres have different roles in mediating various behaviors and higher mental processes (13), there is accumulating evidence that individual differences in perceptual, cognitive, emotional, and imaginal processing reflect individual differences in the degree and nature of the interaction between the hemispheres, in particular in how well the hemispheres coordinate and integrate their respective operations (12, 23–25). As noted by Banich (24), interhemispheric interaction is not merely a passive shuttling of information between the hemispheres but an active process that has both enhancing and constraining effects and allows for integration of the parallel processing of different aspects of information by the specialized processing systems of the right and left hemispheres. Moreover, Banich (24) has shown that "the processing power of the hemispheres working together can surpass that of the separate capabilities of each hemisphere added together." The finding of an interhemispheric transfer deficit in alexithymia suggests that the salient features of the alexithymia construct reflect a limited capability to coordinate and integrate activity in the specialized cognitive, imaginal, and emotional processing systems of the right and left hemispheres. The neural basis of alexithymia may involve other mechanisms as well, of course, as suggested by the studies noted above, in which alexithymia is associated with deficits in the recognition of facial emotions, and by a recent study, in which emotional awareness correlated with increased activity in the anterior cingulate cortex during emotional arousal (26).

Recognizing that interhemispheric transfer of information is critical to the processing of many complex tasks, it is important to acknowledge that the pattern of results shown in Figure 1 are not specific to alexithymia. In a recent study with college students, for example, dyslexic students with associated deficits in phonological processing (the ability to manipulate speech sounds in spoken or written language) were found to perform poorly on complex trials of the tactile finger localization task, especially on the crossed condition, when compared with dyslexic students with higher phonological ability (27).

Given that the tactile finger localization task involves the transfer of sensorimotor information only, future research should assess interhemispheric transfer using a task with affect-laden stimuli, as Zeitlin et al. (8) suggested. Also, because gender and handedness can influence the degree of cerebral lateralization and aspects of interhemispheric interaction (12, 13), future investigations should also determine whether the findings can be generalized to women and left-handed individuals.

	NOTES

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To investigate the possibility that this main effect might be an artifact of the alexithymic group having problems only with the most difficult trials (three- or four-finger trials), a group (alexithymia vs. nonalexithymia) by number of fingers (one vs. two vs. three vs. four) by presentation hand (left vs. right) by response hand (left vs. right) repeated-measures analysis of variance was also conducted. Although a main effect was found for the number of fingers (F(3,81) = 54.18, p < .001), with all respondents making significantly more errors in the three- and four-finger trials than in the one- or two-finger trials, none of the two-, three-, or four-way interactions involving the number of fingers variable was significant. Thus, the difficulty of the task was not related to the alexithymic group’s lower scores on the crossover tasks (compared with the nonalexithymic group’s scores).

Received for publication April 16, 1998.

Revision received April 19, 1999.

	REFERENCES

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1. Nemiah JC, Freyberger H, Sifneos PE. Alexithymia: a view of the psychosomatic process. In: Hill OW, editor. Modern trends in psychosomatic medicine. Vol 3. London: Butterworths; 1976. p. 430–9.
2. Taylor GJ, Bagby RM, Parker JDA. Disorders of affect regulation: alexithymia in medical and psychiatric illness. Cambridge (UK): Cambridge University Press; 1997.
3. Galin D. Hemispheric specialization: implications for psychiatry. In: Grenell RG, Gabay S, editors. Biological foundations of psychiatry. New York: Raven Press; 1976. p. 145–76.
4. Hoppe KD, Bogen JE. Alexithymia in twelve commissurotomized patients. Psychother Psychosom 1977; 28: 148–155.[Medline]
5. Buchanan DC, Waterhouse GJ, West SC. A proposed neurophysiological basis of alexithymia. Psychother Psychosom 1980; 34: 248–55.[Medline]
6. Hoppe KD. Split-brains and psychoanalysis. Psychoanal Q 1977; 46: 220–44.[Medline]
7. TenHouten WD, Hoppe KD, Bogen JE, Walter DO. Alexithymia: an experimental study of cerebral commissurotomy patients and normal control subjects. Am J Psychiatry 1986; 143: 312–6.[Abstract/Free Full Text]
8. Zeitlin SB, Lane RD, O’Leary DS, Schrift MJ. Interhemispheric transfer deficit and alexithymia. Am J Psychiatry 1989; 146: 1434–9.[Abstract/Free Full Text]
9. Geffen G, Nilsson J, Quinn K, Teng EL. The effect of lesions of the corpus callosum on finger localization. Neuropsychologia 1985; 23: 497–514.[Medline]
10. Lassonde M, Sauerwein H, McCabe N, Laurencelle L, Geoffry G. Extent and limits of cerebral adjustment to early section or congenital absence of the corpus callosum. Behav Brain Res 1988; 30: 165–81.[Medline]
11. Dewaraja R, Sasaki Y. A right to left hemisphere callosal transfer deficit of nonlinguistic information in alexithymia. Psychother Psychosom 1990; 54: 201–7.[Medline]
12. Christman SD. Independence versus integration of right and left hemisphere processing: effects of handedness. In: Kitterle FL, editor. Hemispheric communication: mechanisms and models. Hillsdale (NJ): Erlbaum; 1995. p. 231–53.
13. Witelson SF. Neuroanatomical bases of hemispheric functional specialization in the human brain: possible developmental factors. In: Kitterle FL, editor. Hemispheric communication: mechanisms and models. Hillsdale (NJ): Erlbaum; 1995. p. 61–84.
14. Bagby RM, Parker JDA, Taylor GJ. The twenty-item Toronto Alexithymia Scale. I. Item selection and cross-validation of the factor structure. J Psychosom Res 1994; 38: 23–32.[Medline]
15. Bagby RM, Taylor GJ, Parker JDA. The twenty-item Toronto Alexithymia Scale. II. Convergent, discriminant, and concurrent validity. J Psychosom Res 1994; 38: 33–40.[Medline]
16. Dean RS. Lateral preference schedule. Odessa, FL: Psychological Assessment Resources; 1988.
17. Quinn K, Geffen G. The development of tactile transfer of information. Neuropsychologia 1986; 24: 793–804.[Medline]
18. Piccirilli M, Finali G, Sciarma T. Negative evidence of difference between right- and left-handers in interhemispheric transfer of information. Neuropsychologia 1989; 27: 1023–6.[Medline]
19. Parker JDA, Taylor GJ, Bagby RM. Alexithymia and the recognition of facial expressions of emotion. Psychother Psychosom 1993; 59: 197–202.[Medline]
20. Mann LS, Wise TN, Trinidad A, Kohanski R. Alexithymia, affect recognition, and the five-factor model of personality in normal subjects. Psychol Rep 1994; 74: 563–7.[Medline]
21. Lane RD, Sechrest L, Reidel R, Weldon V, Kaszniak A, Schwartz GE. Impaired verbal and nonverbal emotion recognition in alexithymia. Psychosom Med 1996; 58: 203–10.[Abstract/Free Full Text]
22. Davidson RJ. The neuropsychology of emotion and affective style. In: Lewis M, Haviland JM, editors. Handbook of emotions. New York: Guilford Press; 1993. p. 143–54.
23. Kosslyn SM. Seeing and imaging in the cerebral hemispheres: a computational approach. Psychol Rev 1987; 94: 148–75.[Medline]
24. Banich MT. Interhemispheric interaction: mechanisms of unified processing. In: Kitterle FL, editor. Hemispheric communication: mechanisms and models. Hillsdale (NJ): Erlbaum; 1995. p. 271–300.
25. Pally R. Bilaterality: hemispheric specialisation and integration. Int J Psychoanal 1998; 79: 565–78.
26. Lane RD, Reiman EM, Axelrod B, Yun L-S, Holmes A, Schwartz GE. Neural correlates of levels of emotional awareness: evidence of an interaction between emotion and attention in the anterior cingulate cortex. J Cogn Neurosci 1998; 10: 525–35.[Medline]
27. Moore LH, Brown WS, Markee TE, Theberge DC, Zvi JC. Callosal transfer of finger localization information in phonologically dyslexic adults. Cortex 1996; 32: 311–22.[Medline]

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This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Parker, J. D. A. Articles by Taylor, G. J. Search for Related Content PubMed PubMed Citation Articles by Parker, J. D. A. Articles by Taylor, G. J. Related Collections Neurology Personality Stress and Coping