Poster #: 74
Topic: MMN across modalities
Thursday, Sep 10, 2015
Laminar processing of sensory deviations in the somatosensory cortex
1Brain Research Institute, University of Zurich, Zurich, Switzerland
2Institute of Neuroinformatics, University of Zurich and ETH Zurich, Zurich, Switzerland
3Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
4Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
Stimulus-specific adaptation (SSA) has been proposed as a potential mechanism to separate behaviorally relevant features from a stream of continuous sensory information and as a potential contributor to the generation of mismatch negativity (MMN). However, the mechanism giving rise to SSA and its effect on sensory perception is unknown. To address these issues, we investigated the behavioral implications of SSA in a deviance detection paradigm and characterized neural responses to deviant stimuli in rat somatosensory cortex.
We trained rats to detect single-whisker deviant stimuli and found that detection performance was strongly enhanced when deviants differed in multiple features (identity of deflected whisker, deflection direction or deflection velocity) from background stimulation. Likewise, changes in different stimulus features also evoked robust SSA in single neurons in somatosensory cortex. Surprisingly, SSA was weakest in the input layer IV and significantly stronger in the supra- and infra-granular layers, implying that a major part of SSA is generated within the cortex. This was corroborated by a late sensory response, occurring in a subpopulation of layer IV neurons roughly 200 ms after stimulus offset and that exibited true deviant detection properties.
Our study provides the first behavioral evidence for enhanced perception of rare deviant stimuli, characterized by a set of specific stimulus features. Moreover, we found that deviant responses are actively amplified within cortex, especially in the supragranular layers. These results demonstrate the functional importance of cortical SSA and strongly implicate deviance detection as a feature of intracortical stimulus processing.