Prefrontal cortex controls human balance during overground ataxic gait

Purpose: 1) to verify if prefrontal cortex (PFC) is activated during over ground walking in ataxic patients, 2) to correlate the clinical parameters of gait with the PFC activation patterns. Methods: Fourteen patients and 20 healthy subjects were studied. Ataxia was assessed by the Scale for the Assessment and Rating of Ataxia (SARA). A 2-channel near-infrared system was used to investigate the changes in oxygenated ([O2Hb]t) and deoxygenated ([HHb]t) hemoglobin concentrations on the PFC during gait. [O2Hb] baseline-corrected activation values ([O2Hb]c) were calculated by the difference between [O2Hb]t and [O2Hb] during upright posture ([O2Hb]b). Results: [O2Hb]t was increased for both channels (respectively p < 0.01 and p = 0.01) only in the patients. No variation was observed in [HHB]t. The correlation coefficient between [O2Hb]c and the SARA gait score was respectively r: 0.878 (p < 0.01) and r: 0.839 (p < 0.01) for the right and left PFC, between [O2Hb]c and the SARA stance score respectively r: 0.893 (p < 0.01) and r: 0.832 (p < 0.01). Conclusions: During over ground gait PFC is bilaterally activated in patients with severe chronic ataxia. These findings may be associated with compensatory mechanisms which are involved in severe conditions when other nervous centers controlling balance are functionally not efficient.