In the primary visual cortex (V1), a neuronal response to stimulation of the classical receptive field (CRF) is predominantly suppressed by a stimulus presented outside the CRF (extraclassical receptive field, ECRF), a phenomenon referred to as ECRF suppression. To elucidate the neuronal mechanisms and origin of ECRF suppression in V1 of anesthetized cats, we examined the temporal properties of the spatial extent and orientation specificity of ECRF suppression in V1 and the lateral geniculate nucleus (LGN), using stationary-flashed sinusoidal grating. In V1, we found three components of ECRF suppression: (1) local and fast, (2) global and fast, and (3) global and late. The local and fast component, which resulted from within 2° of the boundary of the CRF, started no more than 10 ms after the onset of the CRF response and exhibited low specificity for the orientation of the ECRF stimulus. These spatiotemporal properties corresponded to those of geniculate ECRF suppression, suggesting that the local and fast component of V1 is inherited from the LGN. In contrast, the two global components showed rather large spatial extents ∼5° from the CRF boundary and high specificity for orientation, suggesting that their possible origin is the cortex, not the LGN. Correspondingly, the local component was observed in all neurons of the thalamocortical recipient layer, while the global component was biased toward other layers. Therefore, we conclude that both subcortical and cortical mechanisms with different spatiotemporal properties are involved in ECRF suppression.

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A traveling wave miniature ultrasonic motor has been developed using a helical coiled waveguide as a stator, and it has been applied to an intravascular ultrasound (IVUS) probe. In this motor, the elliptical motion of the surface particle due to flexural ultrasonic waves drives the rotor which can be placed inside or outside adjacent to the stator via frictional force. However, the fact that the rotational direction of the outer rotor is the reverse of that of the inner rotor at low frequencies of the flexural wave has not been clarified theoretically. In this study, the surface particle motion is investigated through finite element method (FEM) simulations, and the basis of the rotational directions is clarified.

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