Supralinear and Supramodal Integration of Visual and Tactile Signals in Rats: Psychophysics and Neuronal Mechanisms

Neuron. 2018 Feb 7;97(3):626-639.e8. doi: 10.1016/j.neuron.2018.01.003. Epub 2018 Jan 27.


To better understand how object recognition can be triggered independently of the sensory channel through which information is acquired, we devised a task in which rats judged the orientation of a raised, black and white grating. They learned to recognize two categories of orientation: 0° ± 45° ("horizontal") and 90° ± 45° ("vertical"). Each trial required a visual (V), a tactile (T), or a visual-tactile (VT) discrimination; VT performance was better than that predicted by optimal linear combination of V and T signals, indicating synergy between sensory channels. We examined posterior parietal cortex (PPC) and uncovered key neuronal correlates of the behavioral findings: PPC carried both graded information about object orientation and categorical information about the rat's upcoming choice; single neurons exhibited identical responses under the three modality conditions. Finally, a linear classifier of neuronal population firing replicated the behavioral findings. Taken together, these findings suggest that PPC is involved in the supramodal processing of shape.

Keywords: Bayesian; linearity; multimodal integration; mutual information; neuronal coding; posterior parietal cortex; psychophysics; rat; touch; vision.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Choice Behavior
  • Discrimination, Psychological / physiology*
  • Male
  • Neurons / physiology*
  • Parietal Lobe / physiology*
  • Photic Stimulation
  • Physical Stimulation
  • Psychomotor Performance
  • Psychophysics
  • Rats, Long-Evans
  • Touch Perception / physiology*
  • Visual Perception / physiology*