Interlimb communication: Crossed reflexes in the human biceps femoris muscle

A continual coordination between the two legs is necessary for maintaining a symmetric walking pattern and adapting to changes in the external environment. Recent evidence in animals and humans suggests that spinal interneuronal circuits under supraspinal control may mediate communication between the lower limbs. The overall objective of the present thesis was to further investigate and elucidate neural pathways underlying interlimb communication in humans, focusing primarily on the possible interlimb connections to the biceps femoris muscle. The major aims were 1) to investigate whether interlimb reflexes are present in sitting and walking following ipsilateral knee (iKnee) joint rotations (Studies I and III), 2) to elucidate the neural pathways involved in mediating the interlimb reflexes (Studies I, II and III), and 3) to investigate the functional role of the observed interlimb reflexes during walking (Study IV).

The results of the this thesis provide new insights into the neural mechanisms underlying human interlimb communication, as well as their functional relevance to human locomotion. Although it is difficult to propose the exact neural pathways mediating interlimb reflexes to the contralateral biceps femoris muscle, this thesis provides the basis for future studies.