ABSTRACT
Perceptual decision making is an active process where animals move their sense organs to extract task-relevant information. To investigate how the brain translates sensory input into decisions during active sensation, we developed a mouse active touch task where the mechanosensory input can be precisely measured and that challenges animals to use multiple mechanosensory cues. Mice were trained to localise a pole using a single whisker and to report their decision by selecting one of three choices. Using high-speed imaging and machine vision we estimated whisker-object mechanical forces at millisecond resolution. Mice solved the task by a sensory-motor strategy where both the strength and direction of whisker bending were informative cues to pole location. We found competing influences of immediate sensory input and choice memory on mouse choice. On correct trials, choice could be predicted from the direction and strength of whisker bending, but not from previous choice. In contrast, on error trials, choice could be predicted from previous choice but not from whisker bending. This study shows that animal choices during active tactile decision making can be predicted from mechanosenory and choice-memory signals; and provides a new task, well-suited for future study of the neural basis of active perceptual decisions.
SIGNIFICANCE STATEMENT Due to the difficulty of measuring the sensory input to moving sense organs, active perceptual decision making remains poorly understood. The whisker system provides a way forward since it is now possible to measure the mechanical forces due to whisker-object contact during behaviour. Here we train mice in a novel behavioural task that challenges them to use rich mechanosensory cues, but can be performed using one whisker and enables task-relevant mechanical forces to be precisely estimated. This approach enables rigorous study of how sensory cues translate into action during active, perceptual decision making. Our findings provide new insight into active touch and how sensory/internal signals interact to determine behavioural choices.
Author contribution
Designed research: CD, RSP, KS
Performed research: CD, KC, DP, SF
Contributed unpublished analytic tools: MHE, MH
Analyzed data: CD, MHE,ACR, MSEL, SF
Wrote the first draft of the paper: CD, RSP
Edited the paper: CD, RSP, MHE, KS, MH
Acknowledgements
We dedicate this paper to the memory of Katarina Chlebikova. We thank Luciana Walendy and Nuo Li for their support with behavioural training; Robert Lucas for comments on the manuscript; Tiago Branco and Branco laboratory members for discussion. This work was funded by Biotechnology and Biological Sciences Research Council (BB/L007282/1, BB/ P021603/1), Medical Research Council (MR/L01064X7/1, MR/P005659/1), Wellcome Trust (097820/Z/11/B) and HHMI.
Footnotes
Current affiliation of the authors: DC, Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, London, United Kingdom; DP, School of Biosciences, University of Birmingham, Birmingham, United Kingdom; MHE, MH, School of Psychology, University of Nottingham, United Kingdom.
The authors declare no competing financial interests.