Wheel running behavior is impaired by both surgical section and genetic absence of the mouse corpus callosum

Abstract

These results are not totally conclusive because the strains in question also show a number of behavioral peculiarities that are unrelated to the effects of an absent CC [2,18,20,26], and it remains possible that effects of absent CC may depend on the strain background, just as CC absence does [22]. The present paper addresses this limitation by utilizing several recombinant inbred lines created from the 129 and BALB/c strains, so that genes responsible for absence of the CC would not likely be spuriously correlated with genes relevant for abnormal behavior.The literature on humans lacking the CC points to mild, language-related deficits in intelligence and rhyming [10,24], and it suggests that deficits are most likely to appear on motor tasks, in which pressure exists to perform at high speed [14,23]. In this paper, we report that CC-related deficits in high-speed wheel running indeed appear when the task is rendered more difficult by removing several rungs from the wheel.The interpretation of behavioral test results from acallosal mice is challenging because usually no compelling reason exists to believe that the behaviors in question rely heavily on interhemispheric communication. It is also possible that as with human CC agenesis [9,11,19,29], developmental plasticity creates or pre-serves alternative

Survey of 21 inbred mouse strains in two laboratories reveals that BTBR T/+ tf/tf has severely reduced hippocampal commissure and absent corpus callosum

“…Hereditary absence and surgical section of the CC impair performance on a challenging task involving high speed motor performance [16]. Nevertheless, strain BTBR T/ + tf/tf is among the best performers on the accelerating rotarod test of motor coordination [14,15].…”

The corpus callosum as an evolutionary innovation

“…Contrary to their marsupial counterparts, rats thus displayed a large variety of movements when trying to catch live crickets, such as manipulating prey before ingestion, making various rotatory movements of aiming, pronation and supination when catching their prey and used their digits extensively. Schalomon and Wahlsten (2002), moreover, observed that the ability to run at high speeds on a wheel with irregularly spaced rungs was significantly impaired in mice with a congenitally absent or surgically sectioned CC. A similar functional significance of the CC also seems to exist in humans who, in the absence of a CC, show movement control deficits mainly in high-speed motor tasks (Sauerwein et al,'81;Jeeves et al,'88).…”

“…The CC has been found to play a role in various sensory and motor functions such as binocular convergence and stereoscopic vision (Gazzaniga, 2000), the transfer of learned visual discrimination (Deng and Elberger, 2001), midline fusion of the two visual hemifields (Houzel and Milleret,'99), bimanual coordination (Schalomon and Wahlsten, 2002) and sound localization (Aboitiz and Montiel, 2003). Due to its role in connecting the topographical sensory areas of the two hemispheres, it has been proposed, moreover, that the CC may be involved in the visualization of objects moving from one visual field to the other at high speed (Milleret and Houzel, 2001;Houzel et al, 2002).…”

“…In spite of these numerous functions of the CC it has been found that sectioning of the CC in humans and other eutherian species does not produce any dramatic long-term effects apart from a set of peculiar abnormalities described as callosal disconnection syndrome (Gazzaniga, 2000;Schalomon and Wahlsten, 2002). In fact, callosectomy is sometimes administered in cases of severe epilepsy in order to prevent the interhemispheric spread of epileptic fits (Aboitiz et al, 2003).…”

Midline Splenial Lesion after Aneurysmal Subarachnoid Hemorrhage

“…Mutations producing the absence of the corpus callosum are not uncommon, and if there were no adaptive value in this structure it would be common to find placental lineages in which the corpus callosum had been lost. In addition, it is surprising that few dramatic long-term effects beside the callosal disconnection syndrome are seen after section of the corpus callosum in humans and in other animals (4,5). Therefore, the question arises about the adaptive value of the largest fiber tract in the placental nervous system.…”