The polarization of light is a light quality invisible for the human eye. However, the sensitivity to the angle of light polarization to enhance visual contrast has been recognized in a number of animals inhabiting aquatic environments. So far, the visual mechanisms underlying such capabilities remain unknown. In the last couple of years we have studied the mechanisms underlying polarization vision in the crab Neohelice granulata. We have quantified animals’ escape response and changes in heart rate as indexes of visual sensitivity. By presenting polarized motion stimuli with only linear polarization contrast (no intensity or spectral contrast) we observed maximum animals’ responses when object and background polarizations were aligned with the vertical and horizontal orientations. The addition of polarization contrast to threatening intensity contrast stimuli enhanced significantly a low threshold alert response of the animals but produced no effect on higher threshold defensive behaviors. In line with theoretical models, our results provide experimental evidence that crabs perform a two-channel (vertical/horizontal) computation to achieve polarization contrast vision. We will discuss how such a two channel system maximizes information acquisition in the animals’ natural environment together with the limitations that polarization information processing might have.
How different plasticity mechanisms act together in vivo and at a cellular level to transform sensory information into behavior is not well understood. We show that in Caenorhabditis elegans two plasticity mechanisms-sensory adaptation and presynaptic plasticity-act within a single cell to encode thermosensory information and actuate a temperature preference memory. Sensory adaptation adjusts the temperature range of the sensory neuron (called AFD) to optimize detection of temperature fluctuations associated with migration. Presynaptic plasticity in AFD is regulated by the conserved kinase nPKCε and transforms thermosensory information into a behavioral preference. Bypassing AFD presynaptic plasticity predictably changes learned behavioral preferences without affecting sensory responses. Our findings indicate that two distinct neuroplasticity mechanisms function together through a single-cell logic system to enact thermotactic behavior.
Behavioural data collection for cognitive (neuro)science traditionally takes place in a physical laboratory environment: participants come to the lab, receive instructions from an experimenter and complete a computer-based task. This provides high control over stimulus presentation and participants’ behaviour, but also comes at a very high cost in time and money. This naturally sets a limit to the number of participants that can be collected, and is one of the factors contributing to the reproducibility crisis in the field. As an alternative, in cases where only behavioural data are collected, experiments can be conducted online, with participants performing cognitive tasks from their homes and submitting result data through the Internet. This dramatically decreases the time and costs required to collect a full dataset, in turn allowing for larger, more diverse —and thus more representative— samples than the common sample of university students.
We have developed an open-source web application to assist in setting up a server for online data collection (JATOS, jatos.org). JATOS supports online studies, including longitudinal and group studies. I will detail the requirements to run a study online, and describe the most common tools available to build and and run studies online. I will also give an overview of the advantages and (more importantly), limitations of collecting data online.
Circadian rhythms have been extensively studied in Drosophila, however, still little is known about how the electrical properties of clock neurons are specified. We have performed a behavioral genetic screen through the downregulation of candidate ion channels in the lateral ventral neurons (LNvs) and show that the hyperpolarization-activated cation current Ih is important for the behaviors that the LNvs command: temporal organization of locomotor activity and sleep. Using whole-cell patch clamp electrophysiology we demonstrate that small LNvs are bursting neurons, and that Ih is necessary to achieve the high frequency bursting firing pattern characteristic of both types of LNvs. Since firing in bursts has been associated to neuropeptide release, we hypothesized that Ih would be important for LNvs communication. Indeed, we demonstrate that Ih is fundamental for the recruitment of PDF filled dense core vesicles to the terminals at the dorsal protocerebrum and for their timed release, affecting the temporal coordination of circadian behaviors.