Interhemispheric transfer following callosotomy in humans: Role of the superior colliculus

Silvia Savazzi, Mara Fabri, Guido Rubboli, Aldo Paggi, Carlo Alberto Tassinari, Carlo Alberto Marzi

Research output: Contribution to journalArticle


It is now common knowledge that the total surgical section of the corpus callosum (CC) and of the other forebrain commissures prevents interhemispheric transfer (IT) of a host of mental functions. By contrast, IT of simple sensorimotor functions, although severely delayed, is not abolished, and an important question concerns the pathways subserving this residual IT. To answer this question we assessed visuomotor IT in split-brain patients using the Poffenberger paradigm (PP), that is, a behavioral paradigm in which simple reaction time (RT) to visual stimuli presented to the hemifield ipsilateral to the responding hand is compared to stimuli presented to the contralateral hemifield, a condition requiring an IT. We tested the possibility that the residual IT is mediated by the collicular commissure interconnecting the two sides of the superior colliculus (SC). To this purpose, we used short-wavelength visual stimuli, which in neurophysiological studies in non-human primates have been shown to be undetectable by collicular neurons. We found that, in both totally and partially callosotomised patients, IT was considerably longer with S-cone input than with L-cone input or with achromatic stimuli. This was not the case in healthy participants in whom IT was not affected by color. These data clearly show that the SC plays an important role in IT of sensorimotor information in the absence of the corpus callosum.

Original languageEnglish
Pages (from-to)2417-2427
Number of pages11
Issue number11
Publication statusPublished - 2007



  • Corpus callosum
  • Poffenberger paradigm
  • S-cones
  • Split-brain

ASJC Scopus subject areas

  • Behavioral Neuroscience
  • Neuropsychology and Physiological Psychology

Cite this

Savazzi, S., Fabri, M., Rubboli, G., Paggi, A., Tassinari, C. A., & Marzi, C. A. (2007). Interhemispheric transfer following callosotomy in humans: Role of the superior colliculus. Neuropsychologia, 45(11), 2417-2427.