Functional topography of the corpus callosum as revealed by fMRI and behavioural studies of control subjects and patients with callosal resection

Fabri, Mara; Polonara, Gabriele

doi:10.1016/j.neuropsychologia.2023.108533

Cited by 12 publications

(9 citation statements)

References 92 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: 72%

“…In the present study, we revisited the left-ear extinction and the effect of directed attention in dichotic listening in two patients (P2 and P3) with complete callosotomy from the Ancona sample (Fabri & Polonara, 2023). As paradigm we utilised the standardised Bergen dichotic-listening paradigm (Hugdahl & Andersson, 1986;Hugdahl et al, 2009), which uses stop-consonant-vowel (CV) syllables (e.g., /ba/, /pa/) as stimulus material and includes a freereport (called non-forced condition, NF), as well as two selective (or forced) attention conditions demanding to only attend to and report from one ear at the time.…”

Section: Introductionmentioning

confidence: 99%

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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: 72%

Section: Introductionmentioning

confidence: 99%

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

Westerhausen¹,

Fabri²,

Hausmann³

2023

Preprint

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“…Research on patients with various degrees of callosotomy have clarified results mainly relating to simple sensory or motor functions, specifically which callosal routes facilitate transfer different kinds of sensory and motor information between the two hemispheres. These findings with the Ancona group of patients has been described and summarized (Fabri et al, 2017;Fabri and Polonara, 2023).…”

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confidence: 84%

Editorial: The legacy of Dr. Roger W. Sperry: current advances in brain lateralization and interhemispheric transfer

Zaidel,

Fabri

2024

Front. Hum. Neurosci.

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Editorial on the Research TopicThe legacy of Dr. Roger W. Sperry: current advances in brain lateralization and interhemispheric transfer Roger W. Sperry's Nobel Prize for Physiology or Medicine in 1981 (shared with David Hubel and Torsten Wiesel) was awarded for elucidating functional specialization in the left and right cerebral hemispheres of commissurotomy cases studied at Caltech, Pasadena (Sperry, 1968(Sperry, , 1974. For the first time, scientific light with far reaching implications was shed on the nature of hemispheric specialization, consciousness, and inter-hemispheric communication in the human brain. This followed Sperry (1961Sperry ( , 1964 early long quest to unravel corpus callosum functions, the major inter-hemispheric communication route. Commissurotomy, known in lay terms as "split-brain, " alleviated pharmacologically intractable severe epilepsy (Bogen and Vogel, 1962;Bogen, 1985). The findings in Sperry's lab inspired myriad neuroscientific research into consciousness (

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“… ξ Participants are indicated with an alphanumeric identifier, where “P” stands for “patient” and numbers follow the order of fMRI data acquisition [for the patients, this is in accordance with the article by Fabri and Polonara (2023) ]; P22 is not present in the table referenced, in that, the patient did not participate in the studies described in the article by Fabri and Polonara (2023) . † The scores can vary between 10, which means pure right-handed, and 50, which means pure left-handed.…”

Section: Methodsmentioning

confidence: 99%

Interhemispheric functional connectivity: an fMRI study in callosotomized patients

Marcantoni,

Piccolantonio,

Ghoushi

et al. 2024

Front. Hum. Neurosci.

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IntroductionFunctional connectivity (FC) is defined in terms of temporal correlations between physiological signals, which mainly depend upon structural (axonal) connectivity; it is commonly studied using functional magnetic resonance imaging (fMRI). Interhemispheric FC appears mostly supported by the corpus callosum (CC), although several studies investigating this aspect have not provided conclusive evidence. In this context, patients in whom the CC was resected for therapeutic reasons (split-brain patients) provide a unique opportunity for research into this issue. The present study was aimed at investigating with resting-state fMRI the interhemispheric FC in six epileptic patients who have undergone surgical resection of the CC.MethodsThe analysis was performed using fMRI of the Brain Software Library; the evaluation of interhemispheric FC and the recognition of the resting-state networks (RSNs) were performed using probabilistic independent component analysis.ResultsGenerally, bilateral brain activation was often observed in primary sensory RSNs, while in the associative areas, such as those composing the default mode and fronto-parietal networks, the activation was often unilateral.DiscussionThese results suggest that even in the absence of the CC, some interhemispheric communication is still present. This residual FC might be supported through extra-callosal pathways that are likely subcortical, making it possible for some interhemispheric integration. Further studies are needed to confirm these conclusions.

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Functional topography of the corpus callosum as revealed by fMRI and behavioural studies of control subjects and patients with callosal resection

Cited by 12 publications

References 92 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.

Editorial: The legacy of Dr. Roger W. Sperry: current advances in brain lateralization and interhemispheric transfer

Interhemispheric functional connectivity: an fMRI study in callosotomized patients

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