Disconnected hemispheres and brain areas

Disconnection syndromes are defined as dysfunctions arising when nerve tracts are disrupted. One specific case is the disconnection of corpus callosum or “split-brain” syndrome. This is characterized by either a partial or complete disruption of corpus callosum fiber, which is responsible for directly transferring information between the two cerebral hemispheres (Gazzaniga, 2000). Consequently, after a callosotomy, the otherwise integrated information processing of the intact brain is split between the two hemispheres (Sperry, Gazzaniga and Bogen, 1969). This might give rise to two conscious halves within the same brain, if each hemisphere is still intact and equally capable to integrate information as the intact brain (Gazzaniga, 2000; Volz and Gazzaniga, 2017). The aim of this task is to implement and test a surgical procedure for disconnecting the two brain hemispheres by sectioning the corpus callosum, without impairment to the cortex and minimizing damages to the vasculature in rats. The method will provide the background for testing perturbational complexity (Casali et al., 2013; Comolatti et al., 2019) after callosotomy, in order to test if complex cortical dynamics can survive in disconnected hemispheres. The method here described was inspired by previous works in callosotomy (Goodman and Russell, 1974; Crowne and Richardson, 1985) and has been set up by Alessandro Arena and Sarah H Thon. The method contributed in Sarah H Thon's Master Thesis, titled: “A new method for measuring perturbational complexity index in rat model in vivo”, University of Oslo, 2019. The procedures described here are extracted from her thesis.