EVOLUTION has corrected lens reversal by crossing of the optic pathways to the cerebral cortex through an optic chiasm and, secondly, as a motor/sensory pathway crossing’s in the spinal cord or brainstem. Thus by this duel crossing, there is an effective mapping of binocular image fields to the spinal cord were our body image interacts with the virtual object to re-instated symmetrical continuity of right and left between image fields.

• EVOLUTION has corrected lens reversal by crossing of the optic pathways to the cerebral cortex through an optic chiasm and, secondly, as a motor/sensory pathway crossing’s in the spinal cord or brainstem. Thus by this duel crossing, there is an effective mapping of binocular image fields to the spinal cord were our body image interacts with the virtual object to re-instated symmetrical continuity of right and left between image fields.

• The chiasm only corrects the image continuity but pathway crossings (decussations) provides direct sensory and motor reallocation to the appropriate right-left body space. This occurs by motor & sensory decussations in the brainstem and spinal cord.

• As a result, the cerbral cortex, thalamus, basal ganglia, inferior olive and red nucleus - tectum operate on the contralateral side. The cerebellum, deep cerbellar nuclei and brainstem nuclei, motor neurons except the trochlear nucleus are ipsilateral. The deep cerebellar nuclei lie ipsilateral to thte body but decussate to targets related to the cerebral cortex. Thus, ascending sensory paths must also cross to the contralateral thalamus and then to the cortex to match sensory and motor cortical regions.