David Tadres

All Publications

• Using the Raspberry Pi Virtual Reality (PiVR) System to StudyDrosophilaLarval Chemotaxis with Real and Virtual Odor Gradients. Cold Spring Harbor protocols Tadres, D., Saxena, N., Louis, M. 2024; 2024 (7)

  Abstract

  Here, we present a detailed protocol for the study of the orientation behavior of larvae of the fruit fly Drosophila melanogaster in response to both real and virtual odors (chemotaxis). An element common to the study of navigation directed by all sensory modalities is the need to correlate changes in behavioral states (e.g., crawling and turning) with temporal changes in the stimulus preceding these events. It has been shown recently that virtual odor landscapes, with any arbitrary geometry, can be created by combining a platform known as "Raspberry Pi virtual reality" (PiVR) with optogenetics. This methodology offers a technical foundation with which to characterize how the larval nervous system responds to stimulation by real and virtual odors. Furthermore, the experimental steps presented and discussed herein highlight important considerations that are needed to ensure experimental reproducibility. Finally, we believe that this framework can be easily adapted and generalized to allow investigators to study other sensory modalities in the Drosophila larva and in other animals.

  View details for DOI 10.1101/pdb.prot108120

  View details for PubMedID 37258057

• Tracking the Navigation Behavior ofDrosophilaLarvae in Real and Virtual Odor Gradients by Using the Raspberry Pi Virtual Reality (PiVR) System. Cold Spring Harbor protocols Tadres, D., Saxena, N., Louis, M. 2024; 2024 (7)

  Abstract

  In a closed-loop experimental paradigm, an animal experiences a modulation of its sensory input as a function of its own behavior. Tools enabling closed-loop experiments are crucial for delineating causal relationships between the activity of genetically labeled neurons and specific behavioral responses. We have recently developed an experimental platform known as "Raspberry Pi Virtual Reality" (PiVR) that is used to perform closed-loop optogenetic stimulation of neurons in unrestrained animals. PiVR is a system that operates at high temporal resolution (>30-Hz) and with low latencies. Larvae of the fruit fly Drosophila melanogaster are ideal to study the role of individual neurons in modulating behavior to aid the understanding of the neural pathways underlying various guided behaviors. Here, we introduce larval chemotaxis as an example of a navigational behavior in which an animal seeks to locate a target-in this case, the attractive source of an odor-by tracking a concentration gradient. The methodologies that we describe here combine the use of PiVR with the study of larval chemotaxis in real and virtual odor gradients, but these can also be readily adapted to other sensory modalities.

  View details for DOI 10.1101/pdb.top108098

  View details for PubMedID 37258056

• Depolarization block in olfactory sensory neurons expands the dimensionality of odor encoding SCIENCE ADVANCES Tadres, D., Wong, P. H., To, T., Moehlis, J., Louis, M. 2022; 8 (50): eade7209

  Abstract

  Upon strong and prolonged excitation, neurons can undergo a silent state called depolarization block that is often associated with disorders such as epileptic seizures. Here, we show that neurons in the peripheral olfactory system undergo depolarization block as part of their normal physiological function. Typically, olfactory sensory neurons enter depolarization block at odor concentrations three orders of magnitude above their detection threshold, thereby defining receptive fields over concentration bands. The silencing of high-affinity olfactory sensory neurons produces sparser peripheral odor representations at high-odor concentrations, which might facilitate perceptual discrimination. Using a conductance-based model of the olfactory transduction cascade paired with spike generation, we provide numerical and experimental evidence that depolarization block arises from the slow inactivation of sodium channels-a process that could affect a variety of sensory neurons. The existence of ethologically relevant depolarization block in olfactory sensory neurons creates an additional dimension that expands the peripheral encoding of odors.

  View details for DOI 10.1126/sciadv.ade7209

  View details for Web of Science ID 000905194200019

  View details for PubMedID 36525486

  View details for PubMedCentralID PMC9757753

• PiVR: An affordable and versatile closed-loop platform to study unrestrained sensorimotor behavior. PLoS biology Tadres, D., Louis, M. 2020; 18 (7): e3000712

  Abstract

  Tools enabling closed-loop experiments are crucial to delineate causal relationships between the activity of genetically labeled neurons and specific behaviors. We developed the Raspberry Pi Virtual Reality (PiVR) system to conduct closed-loop optogenetic stimulation of neural functions in unrestrained animals. PiVR is an experimental platform that operates at high temporal resolution (70 Hz) with low latencies (<30 milliseconds), while being affordable (

  View details for DOI 10.1371/journal.pbio.3000712

  View details for PubMedID 32663220

  View details for PubMedCentralID PMC7360024