[en] This paper gives a brief review of recent results of rheo-dielectric studies for oligo-styrene (OS) and cis-polyisoprene (PI). OS has type-B dipoles perpendicular to the backbone, and its dielectric α relaxation (glassy mode relaxation) is accelerated under the shear flow even at rates much smaller than the equilibrium relaxation frequency. This acceleration, resulting in the decrease of the viscosity (thinning) observed at those rates, is related to flow-induced reduction of the cooperativity of the segmental motion. For PI chains, having type-A dipoles parallel to the backbone, the dielectric relaxation detects the global chain motion. For well entangled PI chains, this relaxation is only moderately accelerated and its intensity is only mildly reduced even under fast flow in the non-Newtonian thinning regime. This result is related to a flow-induced orientational cross-correlation of entanglement segments. Within the context of the tube model for entangled chains, this cross-correlation can be related to the dynamic tube dilation induced by the convective constraint release