Sustained Ambulation Without Cues

After an hour or so of practice, T.R. was able to sustain ambulation without the laser spot, provided that he used the spot to initiate. After another hour or so, he could both initiate and sustain ambulation without visual cues. He could in fact walk with his eyes closed. This result came as a complete surprise to all present; nor do we know of a similar case in the literature.

This new skill was retained for two or three months after the trials, although it was very fragile, breaking down in the presence of distractions. At the time, T.R. was not able to explain what the cognitive changes were which allowed him to improve his gait, beyond the statement that it had something to do with concentrating on taking a big initial step. T.R.'s excellent account of his experiences during the trials can be found in Appendix A.

Unfortunately, the general progression of his disease removed his ability to walk without visual cues or by chasing the laser pointer spot. It did not, however, affect his response to physical cues, his ability to walk by stepping over the laser pointer spot, or his ability to respond to cues in the VV Sport display.

The underlying issues here are discussed more fully in Subsection 6.4.1.