Patrick H. Cox¹, Clara A. Scholl², Marissa Laws³, Xiong Jiang⁴, Maximilian Riesenhuber⁴; ¹Lehigh University, ²Applied Physics Laboratory, Johns Hopkins, ³Carnegie Mellon University, ⁴Georgetown University

Object category learning is an extensively studied foundational cognitive process. Typical human category learning paradigms are brief, lasting only a few hours, and generally show a sharpening of shape tuning in visual areas and the formation of task-dependent category responses in prefrontal areas. Other studies have identified a “frontal bottleneck” in the prefrontal cortex that limits processing to one task at a time, potentially limiting our ability to categorize objects in multitasking scenarios. However, many categorizations made in daily life are practiced over months and even years. This extensive practice may be associated with qualitative changes in behavior and underlying neural processing that make categorization more automatic. Here we tested the hypothesis that extensive training leads to a spatiotemporal shift in the neural circuitry underlying categorization. We trained participants on 30,000+ trials over 5-10 weeks to categorize novel morphed car stimuli using a mobile app. We used fMRI and EEG rapid adaptation (RA) techniques to identify the brain regions and temporal dynamics that underlie the categorization process after initial learning (~4 hours over 1 week) and after extensive practice (~16 more hours over 4 more weeks, ~30,000 trials in total). Converging evidence from these EEG and fMRI analyses showed that extensive experience fundamentally remodeled neural task circuitry: ventral occipitotemporal regions in the visual cortex that initially showed shape selectivity changed their profile to become category selective. These brain areas showed decreased functional connectivity with prefrontal cortex and increased connectivity with motor areas after extensive training, supporting the hypothesis that extensive experience leads to a bypassing of the “frontal bottleneck”. Crucially, the decreased connectivity with the prefrontal cortex correlated with increased dual-tasking ability, supporting the hypothesis that extensive practice leads to increased automaticity.

Acknowledgements: NSF (BCS-1232530)