Naber, C. | Search bioRxiv

bioRxiv2025

Multimodal characterization and optogenetic potential of the bistable Gi/o-coupled vertebrate ancient opsin from the flashlight fish Anomalops katoptron

Vertebrate ancient long opsin, or VAL opsin, is a light-sensitive protein that is found within and outside the visual system in vertebrates. In accordance with its wide distribution in the retina, brain, testis and skin, VAL is suggested to play a role in light-dependent physiological processes that are beyond vision. However, many aspects of the physiological properties and specific functions of VAL remain unclear. Here we identified and characterized the VAL opsin from the flashlight fish Anomalops katoptron (AkVAL) and show that this opsin is bistable and reversibly converts between active and inactive states by responding to cycles of green and blue/UV lights. We further show that AkVAL couples to the Gi/o pathway and controls the activity of GIRK channels in a bistable manner. In line with this, we demonstrated that AkVAL modulates neuronal activity in cerebellar Purkinje cells, where neuronal activity is reduced by UV/blue light and increased by green/red light illumination. In addition, upon the in vivo expression of AkVAL in neurons innervating body muscles of Caenorhabditis elegans the worms body movement can be bidirectionally controlled altering blue/UV and green illuminations. These data highlight the potential of AkVAL as an optogenetic tool to control cells in vitro and in vivo, in a bistable manner.

neuroscience↗

bioRxiv2024

Audiomotor prediction errors drive speech adaptation even in the absence of overt movement

Observed outcomes of our movements sometimes differ from our expectations. These sensory prediction errors recalibrate the brains internal models for motor control, reflected in alterations to subsequent movements that counteract these errors (motor adaptation). While leading theories suggest that all forms of motor adaptation are driven by learning from sensory prediction errors, dominant models of speech adaptation argue that adaptation results from integrating time-advanced copies of corrective feedback commands into feedforward motor programs. Here, we tested these competing theories of speech adaptation by inducing planned, but not executed, speech. Human speakers were prompted to speak a word and, on a subset of trials, were rapidly cued to withhold the prompted speech. On standard trials, speakers were exposed to real-time playback of their own speech with an auditory perturbation of the first formant to induce single-trial speech adaptation. Speakers experienced a similar sensory error on movement cancellation trials, hearing a perturbation applied to a recording of their speech from a previous trial at the time they would have spoken. Speakers adapted to auditory prediction errors in both contexts, altering the spectral content of spoken vowels to counteract formant perturbations even when no actual movement coincided with the perturbed feedback. Such adaptation was not observed when participants passively listened to perturbed feedback without the intention to speak, ruling out observational learning as the cause of adaptation in movement cancellation trials. These results build upon recent findings in reaching, and suggest that prediction errors, rather than corrective motor commands, drive audiomotor adaptation in speech.

neuroscience↗