Typical cerebral hemisphere disconnection deficits following corpus callosum section despite sparing of the anterior commissure

McKeever, Walter F.; Sullivan, Kathleen F.; Ferguson, Shirley M.; Rayport, Mark

doi:10.1016/0028-3932(81)90086-5

Cited by 37 publications

(8 citation statements)

References 10 publications

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“…This pattern is also found when comparing the performance before and after the surgery in the same patients (e.g., Musiek, Kibbe, & Baran, 1984;Musiek, Wilson, & Pinheiro, 1979;Risse, LeDoux, Springer, Wilson, & Gazzaniga, 1978;Sidtis, Volpe, Wilson, Rayport, & Gazzaniga, 1981). Furthermore, and in line with the topographical organisation of the corpus callosum (e.g., Fabri & Polonara, 2023;Schmahmann & Pandya, 2006), partial sections of the corpus callosum appeared to be sufficient to evoke the left-ear extinction, as long as the posterior third of the corpus callosum is affected (McKeever, Sullivan, Ferguson, & Rayport, 1981;Musiek et al, 1984;Musiek, Reeves, & Baran, 1985). Thus, studies on callosotomy patients supported the notion that specifically the ability to recall the left-ear stimulus in dichotic listening relies on the posterior corpus callosum.…”

Section: Introductionsupporting

confidence: 66%

Dichotic-listening performance after complete callosotomy: no relief from left-ear extinction by selective attention.

Westerhausen¹,

Fabri²,

Hausmann³

2023

Preprint

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The surgical section of the corpus callosum (callosotomy) has been frequently demonstrated to result in a left-ear extinction in dichotic listening. That is, callosotomy patients report the left-ear stimulus below chance level, resulting in substantially enhanced right-ear advantage (REA) compared with controls. A small number of previous studies also suggest that callosotomy patients can overcome left-ear extinction when the instruction encourages to attend selectively to the left-ear stimulus. In the present case study, we re-examine the role of selective attention in dichotic listening in two patients with complete callosotomy and 40 age- and sex-matched controls. We used the standardised Bergen dichotic-listening paradigm which uses stop-consonant-vowel syllables as stimulus material and includes both a free-report and selective-attention condition. As was predicted, both patients showed a clear left-ear extinction. However, contrasting the earlier reports, we did not find any evidence for a relief from this extinction by selectively attending to the left-ear stimulus. We conclude that previous demonstrations of an attention-improved left-ear recall in callosotomy patients may be attributed to the use of suboptimal dichotic paradigms or residual callosal connectivity, rather than representing a genuine effect of attention.

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Section: Introductionsupporting

confidence: 66%

Dichotic-listening performance after complete callosotomy: no relief from left-ear extinction by selective attention.

Westerhausen¹,

Fabri²,

Hausmann³

2023

Preprint

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“…However, the AC is found to be enlarged in only 10% of cases with callosal agenesis, and it is entirely absent in another 10% 50. In callosotomy cases, it is unclear whether presence of an intact AC is associated with milder deficits,18 or not 19. On this basis, it would have been expected that the PAX6 patients would exhibit only mild auditory abnormalities, as the CC was present (reduced in size in only three patients) and the AC would be expected to be of lesser importance in auditory interhemispheric transfer, because of its significantly smaller size,7 but also because it contains fibers originating from less differentiated cortical areas 36.…”

Section: Discussionmentioning

confidence: 99%

“…In “split brain” cases, left ear performance in dichotic speech tasks is reduced to near extinction17; performance in both ears for monaural tasks requiring interhemispheric transfer is severely reduced,17, 18 but performance in auditory tasks not requiring such transfer is normal 17. It is not clear whether the presence of an intact anterior commisure in callosotomy cases is associated with milder auditory deficits19 or not,20 or whether hypertrophy of the anterior commisure in cases with corpus callosum agenesis enables functional compensation 21…”

mentioning

confidence: 99%

Deficient auditory interhemispheric transfer in patients with PAX6 mutations

Bamiou

Musiek

Sisodiya

et al. 2004

Annals of Neurology

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PAX6 mutations are associated with absence/hypoplasia of the anterior commissure and reduction in the callosal area in humans. Both of these structures contain auditory interhemispheric fibers. The aim of this study was to characterize central auditory function in patients with a PAX6 mutation. We conducted central auditory tests (dichotic speech, pattern, and gaps in noise tests) on eight subjects with a PAX6 mutation and eight age- and sex-matched controls. Brain magnetic resonance imaging showed absent/hypoplastic anterior commissure in six and a hypoplastic corpus callosum in three PAX6 subjects. The control group gave normal central auditory tests results. All the PAX6 subjects gave abnormal results in at least two tests that require interhemispheric transfer, and all but one gave normal results in a test not requiring interhemispheric transfer. The left ear scores in the dichotic speech tests was significantly lower in the PAX6 than in the control group. These results are consistent with deficient auditory interhemispheric transfer in patients with a PAX6 mutation, which may be attributable to structural and/or functional abnormalities of the anterior commisure and corpus callosum, although the exact contribution of these two formations to our findings remains unclear. Our unique findings broaden the possible functions of PAX6 to include neurodevelopmental roles in higher order auditory processing.

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“…A more obvious candidate for visual transfer in callosal agenesis is the anterior commissure, known to play a role in interhemispheric visual transfer of shape discrimination in the monkey (e.g., Noble, 1968; Sullivan & Hamilton, 1973a, 1973b) and chimpanzee (Black & Myers, 1964). Curiously, though, there is little evidence from comparisons of commissurotomized people with and without surgical section of the anterior commissure that the anterior commissure plays any significant role in vision in the human brain (Holtzman, 1984; McKeever, Sullivan,Ferguson, & Rayport, 1981). It has been suggested that the anterior commissure is enlarged in the acallosal brain relative to the normal brain, but the evidence suggests that this is true in only about 10% of cases of callosal agenesis and that there is a further 10% in which the anterior commissure is too small or lacking altogether (Rauch & Jinkins, 1994).…”

mentioning

confidence: 99%

Interhemispheric visual integration in three cases of familial callosal agenesis.

Corballis

Finlay²

2000

Neuropsychology

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Three cases of callosal agenesis (a 39-year-old woman and her 11- and 12-year-old daughters) were tested on their ability to integrate visual information between the visual hemifields. They were all able to name colors and digits in either hemifield with high accuracy and were able to decide whether letters or digits in opposite hemifields were the same or different. They had greater difficulty deciding whether colors in opposite hemifields were the same or different. When shown 6-letter words made up of pairs of 3-letter words that straddled the midline (e.g., MANAGE, ROTATE), they responded to them as whole words and never as 3-letter words, suggesting perceptual continuity across the midline, at least for verbal material. The most likely interpretation is that the integration of form, but not color, is achieved through the intact anterior commissure in these participants.

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Typical cerebral hemisphere disconnection deficits following corpus callosum section despite sparing of the anterior commissure

Cited by 37 publications

References 10 publications

Dichotic-listening performance after complete callosotomy: no relief from left-ear extinction by selective attention.

Dichotic-listening performance after complete callosotomy: no relief from left-ear extinction by selective attention.

Deficient auditory interhemispheric transfer in patients with PAX6 mutations

Interhemispheric visual integration in three cases of familial callosal agenesis.

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