Hemispheric Organization for Visual Object Recognition: A Theoretical Account and Empirical Evidence

Abstract

Despite the similarity in structure, the hemispheres of the human brain have somewhat different functions. A traditional view of hemispheric organization asserts that there are independent and largely lateralized domain-specific regions in ventral occipitotemporal (VOTC), specialized for the recognition of distinct classes of objects. Here, we offer an alternative account of the organization of the hemispheres, with a specific focus on face and word recognition. This alternative account relies on three computational principles: distributed representations and knowledge, cooperation and competition between representations, and topography and proximity. The crux is that visual recognition results from a network of regions with graded functional specialization that is distributed across both hemispheres. Specifically, the claim is that face recognition, which is acquired relatively early in life, is processed by VOTC regions in both hemispheres. Once literacy is acquired, word recognition, which is co-lateralized with language areas, primarily engages the left VOTC and, consequently, face recognition is primarily, albeit not exclusively, mediated by the right VOTC. We review psychological and neural evidence from a range of studies conducted with normal and brain-damaged adults and children and consider findings which challenge this account. Last, we offer suggestions for future investigations whose findings may further refine this account.

Small-world EEG network analysis of functional connectivity in developmental dyslexia after visual training intervention

“…The processes of the font-perception in the right hemisphere (θstr, γ1str) and an implicit lips-reading in the left hemisphere (θstr, γ1BC ), observed in the pseudoword condition, coexist with processes involved in the bihemispheric presentation of single words and faces (Behrmann and Plaut, 2020). In the pseudoword discrimination at θst frequencies, the right inferior and bilateral middle frontal regions are more likely to participate in earlier stages of font-perception learning of the post-training dyslexics.…”

With Childhood Hemispherectomy, One Hemisphere Can Support--But is Suboptimal for--Word and Face Recognition

“…The visual perception of complex patterns, such as words and faces, is governed by the ventral visual pathway (Barttfeld et al, 2018; Grill-Spector and Malach, 2004; Grill-Spector and Weiner, 2014). Here, word and face recognition is largely, albeit not solely, the product of computations in the left and right hemispheres (LH and RH), respectively (Behrmann and Plaut, 2020, 2015). This hemispheric superiority profile is well-supported by behavioral (Dundas et al, 2013), electrophysiological (Dundas et al, 2014; Maurer et al, 2008; Rossion et al, 2003), and neuroimaging (Dehaene et al, 2002; Hasson et al, 2002; Puce et al, 1996) investigations.…”

“…Thus, the primary objectives of the current study were to determine: 1) whether pediatric patients who develop with only one hemisphere exhibit comparable word and face recognition to age-matched typically developing controls, 2) whether performance is contingent on which hemisphere is preserved, and 3) whether patients’ SF tuning profile of the preserved hemisphere differs from the corresponding hemisphere of controls. That is, despite hemispheric biases that emerge in typical development (Behrmann and Plaut, 2020, 2015), can one hemisphere (either left or right) normatively support both word and face recognition, and is this contingent on the individual’s SF tuning profile?…”

Dissociated face- and word-selective intracerebral responses in the human ventral occipito-temporal cortex

“…Most notably, a category-selective response to faces is found in the lateral parts of the middle fusiform gyrus and in the inferior occipital gyrus, with a right hemispheric dominance (Puce et al, 1995; Kanwisher et al, 1997; Haxby et al, 2000; Grill-Spector et al, 2017 for review) while written words evoke a category-selective response in the left posterior fusiform and occipitotemporal sulcus (Grill-Spector & Weiner, 2014; Devlin et al, 2006). While these findings support the claim that the VOTC contains dissociated neural circuitry for face and written word recognition, fMRI studies showing partial spatial overlap between the functional face- and word-selective regions, in particular the fusiform gyrus (e.g., Dehaene et al, 2010; Harris et al, 2016), have probed researchers to speculate instead that faces and words share the same neural circuitry and functional processes (Behrmann and Plaut, 2020; Behrmann and Plaut, 2013; Nestor et al, 2012; Robinson et al, 2017).…”