An automated system for visual studies

An interactive computer-controlled system is described that is used for visual studies including Visual Evoked Potentials in humans and animals and Visual Receptive Field recordings in animals. Visual stimuli are generated by a display system and the brain activity is monitored by microelectrodes (for animal recordings) and scalp electrodes (for human recordings). The signals are amplified, digitized, and stored. The software uses a response feedback algorithm for mapping the receptive fields. Initially random patterns are presented on a TV monitor and the neural response is recorded. Depending on the response to the pattern and the light distribution in it, the algorithm calculates a new pattern, always trying to maximize the response. As the process goes on, the stimuli patterns become near optimal and thus the receptive field of the neuron is mapped automatically, as a result that for many years has been formed by trial and error. The same system is used for analysis of the recorded results and recordings of the Visual Evoked Potentials in animals and humans. For the human evoked potentials different patterns are generated on the display monitor with a variety of choices, ranging from the simplest (checkerboard and gratings) to the most complicated ones (faces and scenes).