Effects of Diet and/or Exercise in Enhancing Spinal Cord Sensorimotor Learning

Given that the spinal cord is capable of learning sensorimotor tasks and that dietary interventions can influence learning involving supraspinal centers, we asked whether the presence of omega-3 fatty acid docosahexaenoic acid (DHA) and the curry spice curcumin (Cur) by themselves or in combination with voluntary exercise could affect spinal cord learning in adult spinal mice. Using an instrumental learning paradigm to assess spinal learning we observed that mice fed a diet containing DHA/Cur performed better in the spinal learning paradigm than mice fed a diet deficient in DHA/Cur. The enhanced performance was accompanied by increases in the mRNA levels of molecular markers of learning, i.e., BDNF, CREB, CaMKII, and syntaxin 3. Concurrent exposure to exercise was complementary to the dietary treatment effects on spinal learning. The diet containing DHA/Cur resulted in higher levels of DHA and lower levels of omega-6 fatty acid arachidonic acid (AA) in the spinal cord than the diet deficient in DHA/Cur. The level of spinal learning was inversely related to the ratio of AA∶DHA. These results emphasize the capacity of select dietary factors and exercise to foster spinal cord learning. Given the non-invasiveness and safety of the modulation of diet and exercise, these interventions should be considered in light of their potential to enhance relearning of sensorimotor tasks during rehabilitative training paradigms after a spinal cord injury

Corticospinal responses to sustained locomotor exercises: moving beyond single-joint studies of central fatigue

There is substantial evidence that fatiguing exercise is accompanied by changes within the central nervous system that reduce the force that can be produced by working muscles. Here we review studies that used non-invasive neurophysiological techniques to show that sustained single-joint contractions have the capacity to increase corticospinal responsiveness and reduce motoneuronal responsiveness. We contrast these findings with new evidence from our laboratory regarding corticospinal responsiveness during sustained cycling exercise. There seems to be a similar increase in responsiveness of the intracortical inhibitory interneurons during sustained locomotor and single-joint exercise which might be due to acute exercise responses that are common to fatiguing exercise of any nature, such as local accumulation of fatigue metabolites. In contrast, the pattern of changes in corticospinal responsiveness is fundamentally different between the two modes of exercise which might be due to greater systemic fatigue responses to locomotor exercises