Visual neuroscience methods for marmosets: efficient receptive field mapping and head-free eye tracking.

The marmoset has emerged as a promising primate model system, in particular for visual neuroscience. Many common experimental paradigms rely on head fixation and an extended period of eye fixation during the presentation of salient visual stimuli. Both of these behavioral requirements can be challenging for marmosets. Here, we present two methodological developments, each addressing one of these difficulties. First, we show that it is possible to use a standard eye tracking system without head fixation to assess visual behavior in the marmoset. Eye tracking quality from head-free animals is sufficient to obtain precise psychometric functions from a visual acuity task. Secondly, we introduce a novel method for efficient receptive field mapping that does not rely on moving stimuli but uses fast flashing annuli and wedges. We present data recorded during head-fixation in areas V1 and V6 and show that receptive field locations are readily obtained within a short period of recording time. Thus, the methodological advancements presented in this work will contribute to establish the marmoset as a valuable model in neuroscience. Significance Statement The marmoset monkey is becoming an increasingly relevant model for biological and medical research. Here, we present two methodological advancements for visual neuroscience that are adapted to the marmoset. First, we present a head-free eye tracking protocol that is sufficiently accurate for a large variety of visual experiments. Second, we introduce an efficient technique for mapping visual receptive fields (RFs) and apply it to map RFs of neurons from the visual cortex of head-fixed marmosets. The concepts presented in this work can be easily transferred to other species. Together, this will promote diversification of the animal model landscape and solidify the contribution of marmoset research.