Apparatus for measuring neural network activity with a textured semiconductor substrate. Sensor elements have a respective detection electrode on the substrate surface for detecting neural network signals, and the detected neural signals are a basis for outputting electrical sensor output signals via respective sensor element outputs. Each amplifier element has an input and an output. Each of the sensor elements has associated therewith one of the amplifier elements whose input is connected to the sensor output of the respective sensor element. The amplified sensor output signal is output the amplifier output as an amplifier output signal. An activity evaluator has an input, which is connected to at least one of the amplifier outputs, and an output. The activity evaluation device produces an activity signal, which is a measure of activity of the neural network, based on the amplifier output signal, and outputs the amplifier output signal via the evaluation output.