O. Binford, 1971, IEEE Systems Science and Cybernetics Conference, conference; Marr and Nishihara, 1978), defined by both medial axis shape and the volume swept out along the axis. Many of our template models embody surface information superimposed on medial axis structures, and thus would meet this definition of volumetric primitive coding. Combined representation of skeletal and surface structure is particularly relevant for encoding biological shapes. The basic human form, as an example, is characterized not only by a specific axial configuration
of limbs but also by the broad convex surface curvature of the head. Composite axial/surface tuning in high-level visual cortex BIBW2992 mw could provide an efficient, flexible basis for representing such biological shapes and encoding the many postural configurations they can adopt. Thus, our results are potentially relevant in the context of recent studies of anatomical and functional specialization for biological
shape representation. Anatomical segregation of visual processing for biological object categories was originally established by fMRI studies of face and body representation in the human brain (Kanwisher et al., 1997 and Downing et al., 2001). Homologous categorical organization in CFTR modulator old-world monkeys (Tsao et al., 2003 and Moeller et al., 2008) has made it possible to study processing of biological shapes at the level of individual neurons. This work has confirmed the specialization of face modules for face representation GBA3 (Tsao et al., 2006) and begun to distinguish which structural and abstract properties of faces are processed at different levels of the face module system (Freiwald and Tsao, 2010). In particular, neurons in the monkey “middle” face module exhibit tuning for partial configurations of facial features, comparable to the tuning for partial configurations of abstract surface and axial features we describe here (Freiwald et al., 2009). These modules are so small that they require fMRI-based targeting for neural
recording experiments, so it is unlikely that we sampled extensively from them. However, IT as a whole shows strong evidence of sensitivity to biological categories (Kiani et al., 2007 and Kriegeskorte et al., 2008), no doubt reflecting the prevalence and ecological importance of biological shapes in our world. The representation of axial/surface configurations we describe here could provide a structural basis for IT sensitivity to biological categories. Of course, IT represents many other kinds of information about objects, e.g., color (Conway et al., 2007, Koida and Komatsu, 2007 and Banno et al., 2011), that would not entail tuning for axial or surface structure. Two head-restrained rhesus monkeys (Macaca mulatta), a 7.2 kg male and a 5.3 kg female, were trained to maintain fixation within 1° (radius) of a 0.1° diameter spot for 4 s to obtain a juice reward.