The medial temporal lobe enables visual perception not possible 'at a glance'
tyler bonnen, Daniel Yamins, Anthony Wagner, Stanford University, United States
Posters 1 Poster
Pacific Ballroom H-O
Thu, 25 Aug, 19:30 - 21:30 Pacific Time (UTC -7)
Perception unfolds across multiple timescales. Some visual attributes can be inferred 'at a glance' (i.e.<200ms), an ability that largely depends on the ventral visual stream (VVS). Others require more time; determining the identity of a novel object, for example, might require multiple saccades/fixations. Here we report that medial temporal lobe (MTL) structures, downstream of the VVS, enable visual discrimination behaviors not possible 'at a glance.' In experiments with neurotypical (i.e. MTL-intact) human participants we manipulate stimulus presentation times, then compare time-restricted/-unrestricted performance to lesion, neural, and computational data. Given restricted viewing times (e.g. 100ms), neurotypical performance is approximated by a linear readout of the VVS, as well as a computational proxy for the VVS. Time-unrestricted MTL-lesioned patient accuracy continues to resemble VVS-modeled performance. With unrestricted viewing times, however, neurotypical participants dramatically exceed VVS-supported/-modeled performance. In effect, time-restriction induces a 'temporal lesion,' disrupting MTL involvement while sparing VVS-supported performance. This temporal dependence constrains theories of—and highlights potential mechanisms for—MTL involvement in visual object perception.