Limits...
Coding efficiency of fly motion processing is set by firing rate, not firing precision.

Spavieri DL, Eichner H, Borst A - PLoS Comput. Biol. (2010)

Bottom Line: Although these two environmental variables have a considerable impact on the fly's nervous system, they do not impede the fly to behave suitably over a wide range of conditions.We found that the mean firing rate, but not firing precision, changes with temperature, while both were affected by mean luminance.Because we also found that information rate and coding efficiency are mainly set by the mean firing rate, our results suggest that, in the face of environmental perturbations, the coding efficiency is improved by an increase in the mean firing rate, rather than by an increased firing precision.

View Article: PubMed Central - PubMed

Affiliation: Department of System and Computational Neurobiology, Max-Planck-Institute of Neurobiology, Martinsried, Germany.

ABSTRACT
To comprehend the principles underlying sensory information processing, it is important to understand how the nervous system deals with various sources of perturbation. Here, we analyze how the representation of motion information in the fly's nervous system changes with temperature and luminance. Although these two environmental variables have a considerable impact on the fly's nervous system, they do not impede the fly to behave suitably over a wide range of conditions. We recorded responses from a motion-sensitive neuron, the H1-cell, to a time-varying stimulus at many different combinations of temperature and luminance. We found that the mean firing rate, but not firing precision, changes with temperature, while both were affected by mean luminance. Because we also found that information rate and coding efficiency are mainly set by the mean firing rate, our results suggest that, in the face of environmental perturbations, the coding efficiency is improved by an increase in the mean firing rate, rather than by an increased firing precision.

Show MeSH
Time dependent-firing rate.A A segment of the image velocity as a function of time. B Raster plots of the same H1 at different experimental conditions of temperature and light intensity. C Respective average rates calculated using 137 trials for each condition. D Average rates of 325 acquisitions (84 flies) in a wider set of experimental conditions. Scales are the same as indicated in C. For each condition, firing rates of several flies were pooled - n is the sample size and the gray curves are bootstrap confidence intervals (, 1000 replications).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2908696&req=5

pcbi-1000860-g001: Time dependent-firing rate.A A segment of the image velocity as a function of time. B Raster plots of the same H1 at different experimental conditions of temperature and light intensity. C Respective average rates calculated using 137 trials for each condition. D Average rates of 325 acquisitions (84 flies) in a wider set of experimental conditions. Scales are the same as indicated in C. For each condition, firing rates of several flies were pooled - n is the sample size and the gray curves are bootstrap confidence intervals (, 1000 replications).

Mentions: Here, we determine to what extent temperature and luminance influence the firing rate and precision of the responses of an identified wide-field, motion-sensitive neuron in the fly's visual system called ‘H1-cell’ [18], and how the response properties of H1 contribute to information transmission in the system. The H1-cell is located in the posterior part of the third neuropil of the fly's visual system, the so-called lobula plate [19], [20]. It is excited by ipsilateral horizontal back-to-front motion, and inhibited by motion in the opposite direction, i.e. front-to-back. H1 is part of a network of about 60 neurons [21]–[25] that supply the neck and flight motor system with motion information for flight stabilization and course control [26]–[31]. We recorded H1 responses from 84 flies to a square wave grating moving with a time-varying velocity (Fig. 1A) at 42 different combinations of temperature and luminance. The temperature range covered about half of the range flies face under natural conditions. The luminance range covered four orders of magnitude and includes intensities where photon noise effects are common, corresponding to dusk and dawn under natural conditions.


Coding efficiency of fly motion processing is set by firing rate, not firing precision.

Spavieri DL, Eichner H, Borst A - PLoS Comput. Biol. (2010)

Time dependent-firing rate.A A segment of the image velocity as a function of time. B Raster plots of the same H1 at different experimental conditions of temperature and light intensity. C Respective average rates calculated using 137 trials for each condition. D Average rates of 325 acquisitions (84 flies) in a wider set of experimental conditions. Scales are the same as indicated in C. For each condition, firing rates of several flies were pooled - n is the sample size and the gray curves are bootstrap confidence intervals (, 1000 replications).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908696&req=5

pcbi-1000860-g001: Time dependent-firing rate.A A segment of the image velocity as a function of time. B Raster plots of the same H1 at different experimental conditions of temperature and light intensity. C Respective average rates calculated using 137 trials for each condition. D Average rates of 325 acquisitions (84 flies) in a wider set of experimental conditions. Scales are the same as indicated in C. For each condition, firing rates of several flies were pooled - n is the sample size and the gray curves are bootstrap confidence intervals (, 1000 replications).
Mentions: Here, we determine to what extent temperature and luminance influence the firing rate and precision of the responses of an identified wide-field, motion-sensitive neuron in the fly's visual system called ‘H1-cell’ [18], and how the response properties of H1 contribute to information transmission in the system. The H1-cell is located in the posterior part of the third neuropil of the fly's visual system, the so-called lobula plate [19], [20]. It is excited by ipsilateral horizontal back-to-front motion, and inhibited by motion in the opposite direction, i.e. front-to-back. H1 is part of a network of about 60 neurons [21]–[25] that supply the neck and flight motor system with motion information for flight stabilization and course control [26]–[31]. We recorded H1 responses from 84 flies to a square wave grating moving with a time-varying velocity (Fig. 1A) at 42 different combinations of temperature and luminance. The temperature range covered about half of the range flies face under natural conditions. The luminance range covered four orders of magnitude and includes intensities where photon noise effects are common, corresponding to dusk and dawn under natural conditions.

Bottom Line: Although these two environmental variables have a considerable impact on the fly's nervous system, they do not impede the fly to behave suitably over a wide range of conditions.We found that the mean firing rate, but not firing precision, changes with temperature, while both were affected by mean luminance.Because we also found that information rate and coding efficiency are mainly set by the mean firing rate, our results suggest that, in the face of environmental perturbations, the coding efficiency is improved by an increase in the mean firing rate, rather than by an increased firing precision.

View Article: PubMed Central - PubMed

Affiliation: Department of System and Computational Neurobiology, Max-Planck-Institute of Neurobiology, Martinsried, Germany.

ABSTRACT
To comprehend the principles underlying sensory information processing, it is important to understand how the nervous system deals with various sources of perturbation. Here, we analyze how the representation of motion information in the fly's nervous system changes with temperature and luminance. Although these two environmental variables have a considerable impact on the fly's nervous system, they do not impede the fly to behave suitably over a wide range of conditions. We recorded responses from a motion-sensitive neuron, the H1-cell, to a time-varying stimulus at many different combinations of temperature and luminance. We found that the mean firing rate, but not firing precision, changes with temperature, while both were affected by mean luminance. Because we also found that information rate and coding efficiency are mainly set by the mean firing rate, our results suggest that, in the face of environmental perturbations, the coding efficiency is improved by an increase in the mean firing rate, rather than by an increased firing precision.

Show MeSH