Synchrony of hand-foot coupled movements: is it attained by mutual feedback entrainment or by independent linkage of each limb to a common rhythm generator?

Table 1 Statistical comparison between the clk-mov curves of the hand and foot.

	segment	coupled with	coupling main effect	frequency main effect	interaction
isodirectional association	hand unloaded	alone
		foot unloaded	F_(2,18) = 0.32	F_(8,72) = 1.25	F_(16,144) = 1.20
		foot loaded	p = 0.732	p = 0.284	p = 0.274
	foot unloaded	alone
		hand unloaded	F_(2,18) = 1.80	F_(8,72) = 1.98	F_(16,144) = 1.19
		hand loaded	p = 0.194	p = 0.060	p = 0.278
	hand loaded	alone	F_(1,9) = 1.61	F_(8,72) = 3.02	F_(8,72) = 1.02
		foot unloaded	p = 0.236	p < 0.0055*	p = 0.426
	foot loaded	alone	F_(1,9) = 2.66	F_(8,72) = 7.13	F_(8,72) = 0.49
		hand unloaded	p = 0.137	p < 0.000001*	p = 0.856
antidirectional association	hand unloaded	alone
		foot unloaded	F_(2,18) = 0.16	F_(5,45) = 1.94	F_(10,90) = 0.68
		foot loaded	p = 0.854	p = 0.105	p = 0.739
	foot unloaded	alone
		hand unloaded	F_(2,18) = 2.17	F_(5,45) = 1.04	F_(10,90) = 0.96
		hand loaded	p = 0.143	p = 0.406	p = 0.481
	hand loaded	alone	F_(1,9) = 1.71	F_(5,45) = 11.03	F_(5,45) = 1.06
		foot unloaded	p = 0.224	p = 0.000001*	p = 0.394
	foot loaded	alone	F_(1,9) = 1.93	F_(5,45) = 8.06	F_(5,45) = 1.33
		hand unloaded	p = 0.198	p = 0.00002*	p = 0.270

Two-way repeated measures ANOVA, 2 or 3 coupling modalities × 9 frequencies. Direction of movement association is indicated in col.1, moving segment in col.2 and coupling modality in col.3. Significant effects marked by asterisk. In all the configurations examined, the ANOVA test failed to reveal any significant effect of coupling on the clk-mov curves. The p values were very high in two configurations and much lower (0.137 <p < 0.236) in the others. It is worth noting, however, that in all the latter cases, the effect of coupling, even if not significant, was opposite to that expected, i.e. the lagging segment was phase-delayed or the leading segment was phase-advanced.

ISSN: 1471-2202