This chapter reviews work on the method of functional magnetic resonance imaging (fMRI), which has been used to describe the structural and functional anatomy of the human visual system. ■ Exploitation of the endogenous paramagnetic contrast agent deoxyhemoglobin
has yielded functional maps of: - lateral geniculate nucleus of the thalamus
- the columnar organization of primary visual cortex - multiple representations of the visual hemifields in the ventral and dorsal visual pathways - the interface between the visual system and cortical networks underlying the control of oculomotor behavior, visual working memory, and higher visual cognition.
In a significant advance beyond the traditional localistic “one region, one type of processing” paradigm, new methods, such as dynamic causal modeling and discriminant analysis, seek to determine temporal relationships among the fMRI time series of multiple brain regions.
■ Applying these new methods, neuroscientists can discern how spatially distributed brain regions interact via feedforward and feedback signals sent within neural circuits.
■ fMRI promises to contribute more to our understanding of the complex neural circuits that subserve visual perception and visuospatial cognition.