Slide 6
Some neurons increase their firing rate to individual frames even when their sparseness increases with a 3X CRF stimulus.
Figure 6. Comparison of the action potential response to 1X and 3X CRF stimuli in two different cortical neurons. Note that the response to the 3X condition (labeled CRF+nCRF) exhibits higher firing rates to some frames, while the overall response is more selective (meaning the spiking is restricted to a smaller subset of movie frames).