What are the processes involved in determining that there are exactly n objects in the visual field? The core level of representation for this process is based on a mechanism that iteratively individuates each of the set of relevant objects for exact enumeration. In support of this proposal, we review recent electrophysiological findings on enumeration-at-a-glance and consider three temporally distinct responses of the EEG signal that are modulated by object numerosity, and which have been associated respectively with perceptual modulation, attention selection, and working memory. We argue that the neural response associated with attention selection shows the hallmarks of an object individuation mechanism, including the property of simultaneous individuation of a limited number of objects thought to underlie the behavioral subitizing effect. The findings support the view that the core component of exact enumeration is an attention-based individuation mechanism that binds specific features to locations and provides a stable representation of a limited set of relevant objects. The resulting representation is made available for further cognitive operations for exact enumeration.

The placement and development of the visual word form area (VWFA) have commonly been assumed to depend, in part, on its connections with language regions. In this study, we specifically examined the effects of auditory speech experience deprivation in shaping the VWFA by investigating its location distribution, activation strength, and functional connectivity pattern in congenitally deaf participants. We found that the location and activation strength of the VWFA in congenitally deaf participants were highly comparable with those of hearing controls. Furthermore, while the congenitally deaf group showed reduced resting-state functional connectivity between the VWFA and the auditory speech area in the left anterior superior temporal gyrus, its intrinsic functional connectivity pattern between the VWFA and a fronto-parietal network was similar to that of hearing controls. Taken together, these results suggest that auditory speech experience has consequences for aspects of the word form-speech sound correspondence network, but that such experience does not significantly modulate the VWFA's placement or response strength. This is consistent with the view that the role of the VWFA might be to provide a representation that is suitable for mapping visual word forms onto language-specific gestures without the need to construct an aural representation.

Regions in human lateral and ventral occipitotemporal cortices (OTC) respond selectively to pictures of the human body and its parts. What are the organizational principles underlying body part responses in these regions? Here we used representational similarity analysis (RSA) of fMRI data to test multiple possible organizational principles: shape similarity, physical proximity, cortical homunculus proximity, and semantic similarity. Participants viewed pictures of whole persons, chairs, and eight body parts (hands, arms, legs, feet, chests, waists, upper faces, and lower faces). The similarity of multivoxel activity patterns for all body part pairs was established in whole person-selective OTC regions. The resulting neural similarity matrices were then compared with similarity matrices capturing the hypothesized organizational principles. Results showed that the semantic similarity model best captured the neural similarity of body parts in lateral and ventral OTC, which followed an organization in three clusters: (1) body parts used as action effectors (hands, feet, arms, and legs), (2) noneffector body parts (chests and waists), and (3) face parts (upper and lower faces). Whole-brain RSA revealed, in addition to OTC, regions in parietal and frontal cortex in which neural similarity was related to semantic similarity. In contrast, neural similarity in occipital cortex was best predicted by shape similarity models. We suggest that the semantic organization of body parts in high-level visual cortex relates to the different functions associated with the three body part clusters, reflecting the unique processing and connectivity demands associated with the different types of information (e.g., action, social) different body parts (e.g., limbs, faces) convey.

The ability to recognize, create, and use complex tools is a milestone in human evolution. Widely distributed brain regions in parietal, frontal, and temporal cortices have been implicated in using and understanding tools, but the roles of their anatomical connections in supporting tool use and tool conceptual behaviors are unclear. Using deterministic fiber tracking in healthy participants, we first examined how 14 cortical regions that are consistently activated by tool processing are connected by white matter (WM) tracts. The relationship between the integrity of each of the 33 obtained tracts and tool processing deficits across 86 brain-damaged patients was investigated. WM tract integrity was measured with both lesion percentage (structural imaging) and mean fractional anisotropy (FA) values (diffusion imaging). Behavioral abilities were assessed by a tool use task, a range of conceptual tasks, and control tasks. We found that three left hemisphere tracts connecting frontoparietal and intrafrontal areas overlapping with left superior longitudinal fasciculus are crucial for tool use such that larger lesion and lower mean FA values on these tracts were associated with more severe tool use deficits. These tracts and five additional left hemisphere tracts connecting frontal and temporal/parietal regions, mainly overlapping with left superior longitudinal fasciculus, inferior frontooccipital fasciculus, uncinate fasciculus, and anterior thalamic radiation, are crucial for tool concept processing. Largely consistent results were also obtained using voxel-based symptom mapping analyses. Our results revealed the WM structural networks that support the use and conceptual understanding of tools, providing evidence for the anatomical skeleton of the tool knowledge network.

Knowledge of function is critical for selecting objects to meet action goals, even when the affordances of those objects are not mechanical—for instance, both a painting and a vase can decorate a room. To identify neural representations of such abstract function concepts, we asked participants in an fMRI scanner to view a variety of objects and evaluate their utility to each of four goals (two Decoration goals: dress up for a night out and decorate a house, and two Protection goals: protect your body from the cold and keep objects dry in a flooded basement). These task conditions differed in the kind of functional evaluation participants had to perform over objects, but did not vary in the objects themselves. We performed a searchlight multivariate pattern analysis to identify cortical representations in which neural patterns were more similar for the pairs of similar-goal than dissimilar-goal task conditions (Decorate vs. Protect). We report such effects in anterior inferior parietal lobe (aIPL) close to regions typically reported for processing tool-related actions, and thought to be important for representing how they are manipulated. However, the current study design fully controlled for manipulation similarity, which predicted orthogonal relationships among the conditions. We conclude that the aIPL likely has nearby, but distinct, representations of both manipulation and function knowledge, and thereby may have a broader role in understanding how objects can be used, representing not just physical affordances but also abstract functional criteria such as esthetic value or purpose categories such as decorate. This pattern of localization has implications for how semantic knowledge is organized in the brain.

Classical animal visual deprivation studies and human neuroimaging studies have shown that visual experience plays a critical role in shaping the functionality and connectivity of the visual cortex. Interestingly, recent studies have additionally reported circumscribed regions in the visual cortex in which functional selectivity was remarkably similar in individuals with and without visual experience. Here, by directly comparing resting-state and task-based fMRI data in congenitally blind and sighted human subjects, we obtained large-scale continuous maps of the degree to which connectional and functional “fingerprints” of ventral visual cortex depend on visual experience. We found a close agreement between connectional and functional maps, pointing to a strong interdependence of connectivity and function. Visual experience (or the absence thereof) had a pronounced effect on the resting-state connectivity and functional response profile of occipital cortex and the posterior lateral fusiform gyrus. By contrast, connectional and functional fingerprints in the anterior medial and posterior lateral parts of the ventral visual cortex were statistically indistinguishable between blind and sighted individuals. These results provide a large-scale mapping of the influence of visual experience on the development of both functional and connectivity properties of visual cortex, which serves as a basis for the formulation of new hypotheses regarding the functionality and plasticity of specific subregions.

Processing within the dorsal visual stream subserves object-directed action, whereas visual object recognition is mediated by the ventral visual stream. Recent findings suggest that the computations performed by the dorsal stream can nevertheless influence object recognition. Little is known, however, about the type of dorsal stream information that is available to assist in object recognition. Here, we present a series of experiments that explored different psychophysical manipulations known to bias the processing of a stimulus toward the dorsal visual stream in order to isolate its contribution to object recognition. We show that elongated-shaped stimuli, regardless of their semantic category and familiarity, when processed by the dorsal stream, elicit visuomotor grasp-related information that affects how we categorize manipulable objects. Elongated stimuli may reduce ambiguity during grasp preparation by providing a coarse cue to hand shaping and orientation that is sufficient to support action planning. We propose that this dorsal-stream-based analysis of elongation along a principal axis is the basis for how the dorsal visual object processing stream can affect categorization of manipulable objects.

Conspecifics are potential mates, and can be the most dangerous threats. With conspecifics we engage in complex social interactions. Therefore, it is important to rapidly detect the presence of conspecifics in a scene. Images of humans attract attention, and do so already in 9-months-old infants, showing that the distinction between conspecifics and other animals emerges early in development. However, despite a wealth of evidence on the behavioral differences between the processing of conspecifics and other animals, the neural mechanisms that underlie the recognition of conspecifics remain unknown. In this experiment, we used recursive feature elimination to individuate brain regions that show selective effects for the faces of conspecifics, individuating reliable conspecific effects in the right ventrolateral prefrontal cortex (vlPFC). Consistent with the importance of conspecifics recognition for reorienting attention and for social cognition, this region shows functional connectivity with the temporo-parietal junction (TPJ), implicated in reorienting attention and in the attribution of mental states to others. Our results suggest that the right vlPFC plays an important role for the recognition of conspecifics and may function as a gateway for the attribution of mental states to an object.

Reading an action verb elicits the retrieval of its associated body movements as well as its typical goal—the outcome to which it is directed. Two fMRI experiments are reported in which retrieval of goal attributes was isolated from retrieval of motoric ones by contrasting actions that are either done intentionally (e.g., drink) and thus have associated goal information or by accident (e.g., hiccup). Orthogonally, the actions also varied in their motoricity (e.g., drink vs. imagine). Across both levels of motoricity, goal-directedness influenced the activity of a portion of left posterior inferior parietal lobe (pIPL). These effects were not explicable by the grammatical properties, imageability, or amount of body movement associated with these different types of verbs. In contrast, motoricity (across levels of goal-directedness) activated primarily the left middle temporal gyrus. Furthermore, pIPL was found to be distinct from the portion of left parietal lobe implicated in theory of mind, as localized in the same participants. This is consistent with the observation that pIPL contains many functionally distinct subregions and that some of these support conceptual knowledge. The present findings illustrate that, in particular, the pIPL is involved in representing attributes of intentional actions, likely their typical goals, but not their associated body movements. This result serves to describe an attribute-selective semantic subsystem for at least one type of nonmotor aspect of action knowledge.

We argue, by analogy to the neural organization of the object recognition system, that demonstration of modulation of mirror neurons by associative learning does not imply absence of genetic adaptation. Innate connectivity defines the types of processes mirror neurons can participate in while allowing for extensive local plasticity. However, the proper function of these neurons remains to be worked out.