Length Tuning of STMD 1 Neurons Sharply Tuned to Small Features

<p>The strongest spiking response is seen to small bars (0.8° × 3° of the visual field). Larger bars moving through the receptive field elicit no response. Error bars show standard error of the mean of experiments in different neurons of the same STMD class (<i>n</i> = 9). The dashed line shows the output of a model for apparent contrast of targets of different size, as viewed by a single photoreceptor centered on the target (see<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0040054#s4" target="_blank">Materials and Methods</a>). Close fit between the model output and the lower part of the neuron response tuning suggests that attenuation of responses to targets below the optimum is due to reduction in their apparent contrast, not the smaller size per se.