Neuron: question on NOT gate and threshold

This is a neuron of a NOT gate as pictured in Rojas’s ML book. I have a question on it’s behavior. It’s my understanding that the neuron produces a signal if it’s inputs $ x_1$ summed are $ \geq 0$ .

In the following picture, if $ x_1$ is 0, then the threshold 0 is met and there is an output from this neuron. If $ x_1$ is 1, then the threshold is still met and the neuron outputs 1?

Appreciate if anyone can provide guidance on how this neuron works with the inhibitory signal into it.

Thanks

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