Age and interhemispheric transfer time: a failure to replicate

Abstract

In a recent study with the Poffenberger paradigm, Brizzolara et al. reported longer estimates of interhemispheric transfer time (IHTT) for children aged 7 years than for adults. They interpreted this finding as evidence for incomplete functional maturity of the corpus callosum in young children. The present study was we were unable to replicate the age effect reported by Brizzolara et al. A closer look at the original study revealed that only 80 observations per child had been collected, which makes it probable that the larger IHTTs in 7-year-olds were caused by stimulus-response compatibility rather than by the lower efficiency of the corpus callosum during childhood years. © 1997 Elsevier Science B.V.

Revisiting Strephosymbolie: The Connection between Interhemispheric Transfer and Developmental Dyslexia

“…Measures of IHTT were obtained from manual RTs in response to simple visual stimuli, presented tachistoscopically either to the left or to the right visual field of participants. The manual RT measures were based upon a previous report by Ratinckx, Brysbaert, d’Ydewalle [ 35 ] indicating that in children, likewise in adults, the difference in reaction time to a simple stimulus between the hand ipsilateral to the side of stimulation and the hand contralateral to the side of stimulation would reflect the time it took for information to cross the cerebral commissures. IHTT are considered to reliably estimate the interhemispheric transfer efficiency, provided that a sufficient number of trials is used and that attentional and spatial compatibility effects are controlled for as carefully as possible (see [ 15 , 35 ] for developmental studies, and Mooshagian, Iacoboni, Zaidel, 2008, 2009 for clinical groups).…”

“…The manual RT measures were based upon a previous report by Ratinckx, Brysbaert, d’Ydewalle [ 35 ] indicating that in children, likewise in adults, the difference in reaction time to a simple stimulus between the hand ipsilateral to the side of stimulation and the hand contralateral to the side of stimulation would reflect the time it took for information to cross the cerebral commissures. IHTT are considered to reliably estimate the interhemispheric transfer efficiency, provided that a sufficient number of trials is used and that attentional and spatial compatibility effects are controlled for as carefully as possible (see [ 15 , 35 ] for developmental studies, and Mooshagian, Iacoboni, Zaidel, 2008, 2009 for clinical groups). The latter factor was suggested to possibly account for a salient proportion of variance especially at younger ages (see [ 35 ] for comments on the application of such paradigm in developmental studies).…”

“…A subsidiary aim was to explore further possible atypical asymmetries in DD as other studies did [ 15 , 42 , 47 ]. Thus, a Poffenberger’s paradigm with a reasonably high number of trials was used to replicate previous studies [ 6 , 15 , 35 ], and verify whether asymmetries in CUD emerged in the two groups of children. Finally, children were asked to draw and write common objects with both hands, as well as words and numbers.…”

“…The ipsilateral hand-visual field conditions are usually associated with faster RT compared with the contralateral hand-visual field conditions. However, the mean differences in RT between the two conditions (CUD: crossed-uncrossed difference time), are considered a reliable estimate of IHTT, provided that a sufficient number of trials is used and that attentional and spatial compatibility effects are controlled for as carefully as possible (see [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ] for developmental studies; see [ 36 , 37 ] for clinical groups). CUDs are documented to be abnormally long in individuals with callosal defects, either congenital or acquired (whose CUD range from 96 msec to 20 msec in [ 38 ]), hinting that they are a valid measure of callosal efficiency.…”

Brain mapping of bilateral visual interactions in children

“…and of IHT in somatosensory evoked potentials~Salamy, 1978! indicate that both structural and functional maturation of interhemispheric connections is completed by the age of 10, and behavioral studies with visual stimuli suggest that IHT in this modality may already be mature at age 7 Ratinckx, Brysbaert, & d'Ydewalle, 1997!. On the other hand, variable and even negative measures of the time needed for visual IHT have been reported in children~Davidson, Leslie, & Saron, 1990;Gourovitch, Craft, Dowton, Ambrose, & Sparta, 1994!, and no VEP studies have examined interhemispheric processing in children of this age range.…”