Functional Mapping of Face-Selective Regions in the Extrastriate Visual Cortex of the Marmoset

Abstract

The cerebral cortex of humans and macaques has specialized regions for processing faces and other visual stimulus categories. It is unknown whether a similar functional organization exists in New World monkeys, such as the common marmoset (Callithrix jacchus), a species of growing interest as a primate model in neuroscience. To address this question, we measured selective neural responses in the brain of four awake marmosets trained to fix their gaze upon images of faces, bodies, objects, and control patterns. In two of the subjects, we measured high gamma-range field potentials from electrocorticography arrays implanted over a large portion of the occipital and inferotemporal cortex. In the other two subjects, we measured BOLD fMRI responses across the entire brain. Both techniques revealed robust, regionally specific patterns of category-selective neural responses. We report that at least six face-selective patches mark the occipitotemporal pathway of the marmoset, with the most anterior patches showing the strongest preference for faces over other stimuli. The similar appearance of these patches to previous findings in macaques and humans, including their apparent arrangement in two parallel pathways, suggests that core elements of the face processing network were present in the common anthropoid primate ancestor living ϳ35 million years ago. The findings also identify the marmoset as a viable animal model system for studying specialized neural mechanisms related to high-level social visual perception in humans.

Optogenetic manipulation of neural circuits in awake marmosets

“…Data presented in this study suggest that marmosets may be particularly valuable as a model system for application of optogenetic techniques in studies of primate brain function. These methods can be combined with existing behavioral (Chow et al 2015;Miller and Thomas 2012;Mitchell et al 2014;Osmanski et al 2013;Remington et al 2012), neurophysiological (Bendor and Wang 2005;Eliades and Wang 2008;Miller et al 2015;Wang et al 2005), and neuroimaging approaches (Hung et al 2015;Liu et al 2013;Silva et al 2011) in marmosets to more precisely test the functional architecture underlying primate behavior.…”

The evolution of face processing networks

“…Examination into the evolution of cortical networks specialized for face processing has largely relied on comparisons between macaques and humans [1] (Figure 1). A recent paper [2] adds another species to the mix, the common marmoset, whose evolutionary origin is about 10 million years prior to macaques. In combination with recent studies in macaques examining the location of face patches relative to retinotopic areas [3] and natural face motion [4], we are beginning to understand the anatomical and functional features contributing to similarities and differences of the face network across species.…”

“…Specifically, using both electrocorticography (ECoG) and fMRI, Hung and colleagues [2] found that the face network in marmosets consists of six distributed face patches. The anatomical topology of these patches was consistent across methodologies and individual marmosets.…”

“…One such area is MT/V5, which is heavily myelinated in primates. Interestingly, some face patches neighbor MT in marmosets [2], macaques [3], and humans [6]. This consistency across all three species may be partly constrained by myelination differences between MT and neighboring cortex.…”

Towards a comprehensive atlas of cortical connections in a primate brain: Mapping tracer injection studies of the common marmoset into a reference digital template

“…Marmosets have well developed frontal and temporal lobes (e.g. Roberts et al, 2007 ;Burman and Rosa, 2009 ;Hung et al, 2015 ), a sophisticated visual cortex (e.g. Solomon and Rosa, 2014 ;Mitchell and Leopold, 2015 ), multiple cortical areas involved in planning and execution of movements (e.g.…”