Plasticity of human motion processing mechanisms following surgery for infantile esotropia

Abstract

Monocular oscillatory-motion visual evoked potentials (VEPs) were measured in prospective and retrospective groups of infantile esotropia patients who had been aligned surgically at different ages. A nasalward-temporal response bias that is present prior to surgery was reduced below pre-surgery levels in the prospective group. Patients in the retrospective group who had been aligned before 2 yr of age showed lower levels of response asymmetry than those who were aligned after age 2. The data imply that binocular motion processing mechanisms in infantile esotropia patients are capable of some degree of recovery, and that this plasticity is restricted to a critical period of visual development.

The Jitter Spatial Frequency Sweep VEP: A new paradigm to study spatiotemporal development of pattern- and motion-processing mechanisms in human infants.

“…An analogous asymmetry occurs in the cortically-derived motion VEP responses of normal infants (Birch, Fawcett, & Stager, 2000;Bosworth & Birch, 2007;Brosnahan, Norcia, Schor, & Taylor, 1998;Gerth et al, 2008;Jampolsky, Norcia, & Hamer, 1994;Mason, Braddick, WattamBell, & Atkinson, 2001;Norcia, 1996;Norcia et al, 1991;Norcia, Hamer, Jampolsky, & Orel-Bixler, 1995). recorded monocular motion VEPs (MVEPs) in response to sinusoidal gratings undergoing oscillatory motion.…”

“…Based on prior work concerning the DMA Jampolsky et al, 1994;Norcia, 2004;Norcia et al, 1990aNorcia et al, , 1991Norcia et al, , 1995, we can anticipate several response patterns for the JSF sweep VEP depending on age and the ST parameters of the stimulus. For example, for an appropriate choice of spatiotemporal parameters, the monocular F1 response of a normal infant should have a bandpass form, with the low-SF cutoff of the response representing the spatial boundary between mature (symmetrical, low-SF) responses, and immature (asymmetrical, higher-SF) responses.…”

“…Early interruption of binocularity is associated with nasalward/temporalward biases in monocular motion VEP that persist into adulthood Bosworth & Birch, 2007;Hamer, Norcia, Orel-Bixler, & Hoyt, 1993;Jampolsky et al, 1994;Norcia et al, 1991Norcia et al, , 1995Tychsen, Hertig, & Scott, 2004). In addition, there is indirect evidence from adults that the monocular VEP asymmetry measured in normal infants reflects activity of a binocular motion subsystem.…”

“…The AI has been shown to provide a useful index of the degree of asymmetry of the motion responses in both normal and abnormal development Bosworth & Birch, 2007;Jampolsky et al, 1994;Norcia et al, 1995).…”

“…For each bin (or for an average across selected bins), one can calculate an asymmetry index (AI) relating the relative amplitude of the asymmetric (F1) response component to the sum of the F1 and F2 amplitude Jampolsky et al, 1994;Norcia et al, 1995). The AI ranges between a maximum of 1.0 (all energy in the F1 component) to 0 (no F1, all F2).…”