Haptic study of three-dimensional objects activates extrastriate visual areas (original) (raw)
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Visuo-haptic object-related activation in the ventral visual pathway
Nature Neuroscience, 2001
The ventral pathway is involved in primate visual object recognition. In humans, a central stage in this pathway is an occipito-temporal region termed the lateral occipital complex (LOC), which is preferentially activated by visual objects compared to scrambled images or textures. However, objects have characteristic attributes (such as three-dimensional shape) that can be perceived both visually and haptically. Therefore, object-related brain areas may hold a representation of objects in both modalities. Using fMRI to map object-related brain regions, we found robust and consistent somatosensory activation in the occipito-temporal cortex. This region showed clear preference for objects compared to textures in both modalities. Most somatosensory object-selective voxels overlapped a part of the visual object-related region LOC. Thus, we suggest that neuronal populations in the occipito-temporal cortex may constitute a multimodal object-related network.
The neural basis of haptic object processing
Canadian Journal of Experimental Psychology/Revue canadienne de psychologie expérimentale, 2007
We review the organization of the neural networks that underlie haptic object processing and compare that organization with the visual system. Haptic object processing is separated into at least two neural pathways, one for geometric properties or shape, and one for material properties, including texture. Like vision, haptic processing pathways are organized into a hierarchy of processing stages, with different stages represented by different brain areas. In addition, the haptic pathway for shape processing may be further subdivided into different streams for action and perception. These streams may be analogous to the action and perception streams of the visual system and represent two points of neural convergence for vision and haptics.
NeuroImage, 2010
Although visual cortical engagement in haptic shape perception is well established, its relationship with visual imagery remains controversial. We addressed this using functional magnetic resonance imaging during separate visual object imagery and haptic shape perception tasks. Two experiments were conducted. In the first experiment, the haptic shape task employed unfamiliar, meaningless objects, whereas familiar objects were used in the second experiment. The activations evoked by visual object imagery overlapped more extensively, and their magnitudes were more correlated, with those evoked during haptic shape perception of familiar, compared to unfamiliar, objects. In the companion paper (Deshpande et al., this issue), we used task-specific functional and effective connectivity analyses to provide convergent evidence: these analyses showed that the neural networks underlying visual imagery were similar to those underlying haptic shape perception of familiar, but not unfamiliar, objects. We conclude that visual object imagery is more closely linked to haptic shape perception when objects are familiar, compared to when they are unfamiliar.
Human brain mapping, 2010
The occipital and parietal lobes contain regions that are recruited for both visual and haptic object processing. The purpose of the present study was to characterize the underlying neural mechanisms for bimodal integration of vision and haptics in these visuo-haptic object-selective brain regions to find out whether these brain regions are sites of neuronal or areal convergence. Our sensory conditions consisted of visual-only (V), haptic-only (H), and visuo-haptic (VH), which allowed us to evaluate integration using the superadditivity metric. We also presented each stimulus condition at two different levels of signal-to-noise ratio or salience. The salience manipulation allowed us to assess integration using the rule of inverse effectiveness. We were able to localize previously described visuohaptic object-selective regions in the lateral occipital cortex (lateral occipital tactile-visual area) and the intraparietal sulcus, and also localized a new region in the left anterior fusiform gyrus. There was no evidence of superadditivity with the VH stimulus at either level of salience in any of the regions. There was, however, a strong effect of salience on multisensory enhancement: the response to the VH stimulus was more enhanced at higher salience across all regions. In other words, the regions showed enhanced integration of the VH stimulus with increasing effectiveness of the unisensory stimuli. We called the effect ''enhanced effectiveness.'' The presence of enhanced effectiveness in visuo-haptic object-selective brain regions demonstrates neuronal convergence of visual and haptic sensory inputs for the purpose of processing object shape. Hum Brain Mapp 31:678-693,
Neuroimaging studies have shown that the lateral occipito-temporal cortex is involved in multisensory object processing. However, how essential this region is for non-visual object processing remains a matter of controversy. In this preregistered fMRI-guided repetitive transcranial magnetic stimulation (rTMS) study, we examined the causal involvement of the extrastriate body area (EBA) in multisensory object recognition. Participants used either vision or haptics to identify three object categories: hands, teapots (tools), and cars (control objects). Continuous theta-burst stimulation (cTBS) was applied over the left EBA, right EBA, or vertex (control site). Performance for visually perceived hands and teapots (relative to cars) was more strongly disrupted by cTBS over the left EBA than over the vertex, whereas no such object-specific effect was observed in haptics. Instead, exploratory analyses showed that the effect of impaired recognition for all object categories was greater whe...
Dual pathways for haptic and visual perception of spatial and texture information
NeuroImage, 2011
Segregation of information flow along a dorsally directed pathway for processing object location and a ventrally directed pathway for processing object identity is well established in the visual and auditory systems, but is less clear in the somatosensory system. We hypothesized that segregation of location vs. identity information in touch would be evident if texture is the relevant property for stimulus identity, given the salience of texture for touch. Here, we used functional magnetic resonance imaging (fMRI) to investigate whether the pathways for haptic and visual processing of location and texture are segregated, and the extent of bisensory convergence. Haptic textureselectivity was found in the parietal operculum and posterior visual cortex bilaterally, and in parts of left inferior frontal cortex. There was bisensory texture-selectivity at some of these sites in posterior visual and left inferior frontal cortex. Connectivity analyses demonstrated, in each modality, flow of information from unisensory non-selective areas to modality-specific textureselective areas and further to bisensory texture-selective areas. Location-selectivity was mostly bisensory, occurring in dorsal areas, including the frontal eye fields and multiple regions around the intraparietal sulcus bilaterally. Many of these regions received input from unisensory areas in both modalities. Together with earlier studies, the activation and connectivity analyses of the present study establish that somatosensory processing flows into segregated pathways for location and object identity information. The location-selective somatosensory pathway converges with its visual counterpart in dorsal frontoparietal cortex, while the texture-selective somatosensory
Beyond sensory images: Object-based representation in the human ventral pathway
Proceedings of the National Academy of Sciences, 2004
We investigated whether the topographically organized, categoryrelated patterns of neural response in the ventral visual pathway are a representation of sensory images or a more abstract representation of object form that is not dependent on sensory modality. We used functional MRI to measure patterns of response evoked during visual and tactile recognition of faces and manmade objects in sighted subjects and during tactile recognition in blind subjects. Results showed that visual and tactile recognition evoked category-related patterns of response in a ventral extrastriate visual area in the inferior temporal gyrus that were correlated across modality for manmade objects. Blind subjects also demonstrated category-related patterns of response in this ''visual'' area, and in more ventral cortical regions in the fusiform gyrus, indicating that these patterns are not due to visual imagery and, furthermore, that visual experience is not necessary for category-related representations to develop in these cortices. These results demonstrate that the representation of objects in the ventral visual pathway is not simply a representation of visual images but, rather, is a representation of more abstract features of object form.
Functional magnetic resonance imaging (fMRI) studies demonstrated that tactile discrimination evokes patterns of neural response in the extrastriate ventral temporal cortical areas similar to those induced by the visual percept of the same category of objects. These findings strongly indicate that object representation in the ventral visual pathway is not simply a representation of visual images but quite a representation of more abstract features of object form.
Multisensory Interactions between Auditory and Haptic Object Recognition
Cerebral Cortex, 2013
Object manipulation produces characteristic sounds and causes specific haptic sensations that facilitate the recognition of the manipulated object. To identify the neural correlates of audio-haptic binding of object features, healthy volunteers underwent functional magnetic resonance imaging while they matched a target object to a sample object within and across audition and touch. By introducing a delay between the presentation of sample and target stimuli, it was possible to dissociate haptic-to-auditory and auditory-to-haptic matching. We hypothesized that only semantically coherent auditory and haptic object features activate cortical regions that host unified conceptual object representations. The left fusiform gyrus (FG) and posterior superior temporal sulcus (pSTS) showed increased activation during crossmodal matching of semantically congruent but not incongruent object stimuli. In the FG, this effect was found for haptic-to-auditory and auditory-tohaptic matching, whereas the pSTS only displayed a crossmodal matching effect for congruent auditory targets. Auditory and somatosensory association cortices showed increased activity during crossmodal object matching which was, however, independent of semantic congruency. Together, the results show multisensory interactions at different hierarchical stages of auditory and haptic object processing. Object-specific crossmodal interactions culminate in the left FG, which may provide a higher order convergence zone for conceptual object knowledge.