In this paper we present an original neighborhood mechanism for WTM self-organizing Kohonen map implemented in CMOS 0.18 m process. Proposed mechanism is an asynchronous circuit and does not require controlling clock generator. Propagation of an enable signal from a winning neuron to neurons that belong to the winner's neighborhood is very fast. For example radius (R) of the neighborhood equal to 15, total time that is required to start adaptation of all neighboring neurons is below 10 ns. This makes the proposed WTM network in practice as fast as the WTA Kohonen network. When compared to WTM networks implemented, for example in C++, the proposed solution can be even several hundreds times faster and consume much less power.