In the 1960s, David Hubel and Torsten Wiesel made the first systematic recordings from primary visual cortex in cats and monkeys. They succeeded in driving individual cortical neurons by projecting light or dark bars onto a screen in front of the anesthetized animal's eyes. They published their findings as static figures in journals, but in giving talks about their work, Hubel and Wiesel wanted to demonstrate the dynamic nature of the neuronal responses. To accomplish this, they made simple videotape recordings of their experiments using the technology of the time, one-inch reel-to-reel black & white videotape. The technology was so new, however, that it was not generally feasible to play the tapes at other locations. This led them to convert the videotape to black & white 16-mm film, the audiovisual format standard at that time.
To make these historic recordings available online, the 16-mm film was digitized and then converted toQuickTime video. Although the image quality is subpar by modern standards, the historic importance of these experiments makes these videos of enormous interest. The format is simple: the camera shows us the screen on which stimuli were projected, while we hear the action potentials ("clicks") generated by a single cortical neuron.