Behavioral and Neural Bases of Tactile Shape Discrimination Learning in Head-Fixed Mice.

Tactile shape recognition requires the perception of object surface angles. We investigate how neural representations of object angles are constructed from sensory input and how they reorganize across learning. Head-fixed mice learned to discriminate object angles by active exploration with one whisker. Calcium imaging of layers 2–4 of the barrel cortex revealed maps of object-angle tuning before and after learning. Three-dimensional whisker tracking demonstrated that the sensory input components that best discriminate angles (vertical bending and slide distance) also have the greatest influence on object-angle tuning. Despite the high turnover in active ensemble membership across learning, the population distribution of object-angle tuning preferences remained stable. Angle tuning sharpened, but only in neurons that preferred trained angles. This was correlated with a selective increase in the influence of the most task-relevant sensory component on object-angle tuning. These results show how discrimination training enhances stimulus selectivity in the primary somatosensory cortex while maintaining perceptual stability. • Mice can discriminate object surface angle using a single whisker • Excitatory neurons in primary somatosensory cortex represent touched object angles • Object-angle tuning is most affected by vertical bending and slide distance • Training increases the influence of task-relevant sensory inputs on angle tuning Tactile shape recognition requires the perception of object surface angles. Kim et al. show how excitatory neurons in the primary somatosensory cortex construct object-angle representations from sensory input components. Task-relevant sensory components gain influence on object-angle tuning across angle discrimination training, coincident with selective sharpening of trained angle representations. [ABSTRACT FROM AUTHOR]