fMRI Investigations of Visual Recognition and Attention

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Linked publications & trials

Abstract

DESCRIPTION (provided by applicant): Visual object recognition is widely considered to be the central problem of high-level vision. The development of functional MRI (fMRI) has provided a powerful new approach for investigating object recognition, by enabling us to characterize the representations that underlie object recognition and to ask how they change with experience. Here we ask in Specific Aim I what information the ventral visual pathway represents about objects. We use "event-related fMRI adaptation" to test three of the main current proposals, that object representations are composed of i) representations of concave and convex contour segments (Hypothesis I), ii) intuitive object "parts" (Hypothesis II), or iii) wholes (Hypothesis III). In Specific Aim II, we ask how neural representations of objects change with experience. Here we scan people while they view novel stimuli, before and after extensive training on discriminating those stimuli, to test whether this training changes the overall response to the trained objects (Hypothesis IV), increases the sharpness of tuning of neural populations responsive to the trained objects (Hypothesis V), and/or leads to selective responses to the trained stimulus class in focal regions within the ventral visual pathway (Hypothesis VI). We will also test whether training creates representations of trained objects that are specific to the position where they were presented during training (Hypothesis VII), and finally whether training increases the coding of specific combinations of image components (Hypothesis VIII). In Specific Aim III, we ask whether functional heterogeneity in the ventral visual pathway corresponds to anatomical heterogeneity. Here we will coregister functional architecture characterized with fMRI, to post mortem histology, to test Hypothesis IX that cytoarchitectonic subdivisions exist between and within object processing regions of the ventral visual pathway. The methods developed in the first project period have opened up new opportunities for us to make rapid progress answering three of the most fundamental questions about the neural basis of visual recognition: the nature of the representations underlying object recognition, the effects of experience on those representations, and the way those representations differ across distinct regions within the ventral visual pathway.