Scientists at Harvard's Reid Lab have captured video of the visual cortex in cat and rat brains processing visual stimuli. The animals were shown several moving test patterns consisting of alternating black and white lines. The resulting neural activation patterns were revealed using a dye that glows differently based on calcium levels, which change when a neuron activates. R. Clay Reid and the other researchers involved hope the new technique can be used to gain a better understanding of the brain's functional micro-architecture, revealing the relationship between where neurons are and what they do. For a bit more on the subject see a recent CNET story on the research. And if you want the real details, see the Reid researcher's recent paper describing the technique, "Functional Imaging with Cellular Resolution Reveals Precise Micro-architecture in Visual Cortex" (PDF format). Neither article mentions how the 19-40 day old kittens felt about having craniotomies for science or if they survived the procedure - ouch!