RT Journal Article SR Electronic T1 Impact of Photon Noise on the Reliability of a Motion-Sensitive Neuron in the Fly's Visual System JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 10776 OP 10783 DO 10.1523/JNEUROSCI.23-34-10776.2003 VO 23 IS 34 A1 Grewe, Jan A1 Kretzberg, Jutta A1 Warzecha, Anne-Kathrin A1 Egelhaaf, Martin YR 2003 UL http://www.jneurosci.org/content/23/34/10776.abstract AB Variable behavioral responses to identical visual stimuli can, in part, be traced back to variable neuronal signals that provide unreliable information about the outside world. This unreliability in encoding of visual information is caused by several noise sources such as photon noise, synaptic noise, or the stochastic nature of ion channels. Neurons of the fly's visual motion pathway have been claimed to represent perfect encoders, with photon noise as the main noise source limiting their performance. Other studies on the fly's visual system suggest, however, that internal noise emerging within the nervous system also affects the reliability of motion vision. To resolve these contradictory interpretations, we performed an electrophysiological investigation, inspired by the “equivalent noise” paradigm applied in psychophysics, on the fly's motion-sensitive H1 neuron. Noise-like brightness fluctuations of different strength were superimposed on the motion stimuli. Because the noise level found to affect the temporal properties of the spike responses is much larger than the estimate of photon noise under the experimental conditions, our results indicate that motion vision is more likely to be limited by internal sources of variability than by photon noise.