@article {3867, title = {Neural correlates of illusory motion perception in Drosophila.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {108}, year = {2011}, month = {2011 Jun 7}, pages = {9685-90}, abstract = {

When the contrast of an image flickers as it moves, humans perceive an illusory reversal in the direction of motion. This classic illusion, called reverse-phi motion, has been well-characterized using psychophysics, and several models have been proposed to account for its effects. Here, we show that Drosophila melanogaster also respond behaviorally to the reverse-phi illusion and that the illusion is present in dendritic calcium signals of motion-sensitive neurons in the fly lobula plate. These results closely match the predictions of the predominant model of fly motion detection. However, high flicker rates cause an inversion of the reverse-phi behavioral response that is also present in calcium signals of lobula plate tangential cell dendrites but not predicted by the model. The fly{\textquoteright}s behavioral and neural responses to the reverse-phi illusion reveal unexpected interactions between motion and flicker signals in the fly visual system and suggest that a similar correlation-based mechanism underlies visual motion detection across the animal kingdom.

}, keywords = {Algorithms, Animals, Dendrites, Drosophila melanogaster, Female, Humans, Male, Models, Motion, Motion Perception, Neural Pathways, Neurological, Neurons, Time Factors}, issn = {1091-6490}, doi = {10.1073/pnas.1100062108}, author = {Tuthill, John C and Chiappe, M Eugenia and Reiser, Michael B} } @article {1645, title = {Two-photon calcium imaging from head-fixed Drosophila during optomotor walking behavior.}, journal = {Nature Methods}, volume = {7}, year = {2010}, month = {2010 Jul}, pages = {535-40}, abstract = {

Drosophila melanogaster is a model organism rich in genetic tools to manipulate and identify neural circuits involved in specific behaviors. Here we present a technique for two-photon calcium imaging in the central brain of head-fixed Drosophila walking on an air-supported ball. The ball{\textquoteright}s motion is tracked at high resolution and can be treated as a proxy for the fly{\textquoteright}s own movements. We used the genetically encoded calcium sensor, GCaMP3.0, to record from important elements of the motion-processing pathway, the horizontal-system lobula plate tangential cells (LPTCs) in the fly optic lobe. We presented motion stimuli to the tethered fly and found that calcium transients in horizontal-system neurons correlated with robust optomotor behavior during walking. Our technique allows both behavior and physiology in identified neurons to be monitored in a genetic model organism with an extensive repertoire of walking behaviors.

}, keywords = {Animals, Brain, Calcium, Computer-Assisted, Drosophila melanogaster, Fluorescence, Green Fluorescent Proteins, Image Processing, Motion, Motor Activity, Neurons, Signal Transduction, Walking}, issn = {1548-7105}, doi = {10.1038/nmeth.1468}, author = {Seelig, Johannes D and Chiappe, M Eugenia and Lott, Gus K and Dutta, Anirban and Osborne, Jason E and Reiser, Michael B and Jayaraman, Vivek} } @article {3759, title = {Walking modulates speed sensitivity in Drosophila motion vision.}, journal = {Current Biology}, volume = {20}, year = {2010}, month = {2010 Aug 24}, pages = {1470-5}, abstract = {

Changes in behavioral state modify neural activity in many systems. In some vertebrates such modulation has been observed and interpreted in the context of attention and sensorimotor coordinate transformations. Here we report state-dependent activity modulations during walking in a visual-motor pathway of Drosophila. We used two-photon imaging to monitor intracellular calcium activity in motion-sensitive lobula plate tangential cells (LPTCs) in head-fixed Drosophila walking on an air-supported ball. Cells of the horizontal system (HS){\textendash}a subgroup of LPTCs{\textendash}showed stronger calcium transients in response to visual motion when flies were walking rather than resting. The amplified responses were also correlated with walking speed. Moreover, HS neurons showed a relatively higher gain in response strength at higher temporal frequencies, and their optimum temporal frequency was shifted toward higher motion speeds. Walking-dependent modulation of HS neurons in the Drosophila visual system may constitute a mechanism to facilitate processing of higher image speeds in behavioral contexts where these speeds of visual motion are relevant for course stabilization.

}, keywords = {Animals, Calcium, Calcium Signaling, Drosophila, Motion Perception, Photic Stimulation, Walking}, issn = {1879-0445}, doi = {10.1016/j.cub.2010.06.072}, author = {Chiappe, M Eugenia and Seelig, Johannes D and Reiser, Michael B and Jayaraman, Vivek} } @article {1646, title = {Imaging neural activity in worms, flies and mice with improved GCaMP calcium indicators.}, journal = {Nature Methods}, volume = {6}, year = {2009}, month = {2009 Dec}, pages = {875-81}, abstract = {

Genetically encoded calcium indicators (GECIs) can be used to image activity in defined neuronal populations. However, current GECIs produce inferior signals compared to synthetic indicators and recording electrodes, precluding detection of low firing rates. We developed a single-wavelength GCaMP2-based GECI (GCaMP3), with increased baseline fluorescence (3-fold), increased dynamic range (3-fold) and higher affinity for calcium (1.3-fold). We detected GCaMP3 fluorescence changes triggered by single action potentials in pyramidal cell dendrites, with signal-to-noise ratio and photostability substantially better than those of GCaMP2, D3cpVenus and TN-XXL. In Caenorhabditis elegans chemosensory neurons and the Drosophila melanogaster antennal lobe, sensory stimulation-evoked fluorescence responses were significantly enhanced with GCaMP3 (4-6-fold). In somatosensory and motor cortical neurons in the intact mouse, GCaMP3 detected calcium transients with amplitudes linearly dependent on action potential number. Long-term imaging in the motor cortex of behaving mice revealed large fluorescence changes in imaged neurons over months.

}, keywords = {Animals, Brain, Caenorhabditis elegans, Calcium, Cell Line, Drosophila melanogaster, Fluorescence Resonance Energy Transfer, Humans, Mice, Neurons}, issn = {1548-7105}, doi = {10.1038/nmeth.1398}, author = {Tian, Lin and Hires, S Andrew and Mao, Tianyi and Huber, Daniel and Chiappe, M Eugenia and Chalasani, Sreekanth H and Petreanu, Leopoldo and Akerboom, Jasper and McKinney, Sean A and Schreiter, Eric R and Bargmann, Cornelia I and Jayaraman, Vivek and Svoboda, Karel and Looger, Loren L} }