Haptic study of three-dimensional objects activates extrastriate visual areas

Abstract

In humans and many other primates, the visual system plays the major role in object recognition. But objects can also be recognized through haptic exploration, which uses our sense of touch. Nonetheless, it has been argued that the haptic system makes use of 'visual' processing to construct a representation of the object. To investigate possible interactions between the visual and haptic systems, we used functional magnetic resonance imaging to measure the effects of cross-modal haptic-to-visual priming on brain activation. Subjects studied three-dimensional novel clay objects either visually or haptically before entering the scanner. During scanning, subjects viewed visually primed, haptically primed, and non-primed objects. They also haptically explored non-primed objects. Visual and haptic exploration of non-primed objects produced significant activation in several brain regions, and produced overlapping activation in the middle occipital area (MO). Viewing visually and haptically primed objects produced more activation than viewing non-primed objects in both area MO and the lateral occipital area (LO). In summary, haptic exploration of novel three-dimensional objects produced activation, not only in somatosensory cortex, but also in areas of the occipital cortex associated with visual processing. Furthermore, previous haptic experience with these objects enhanced activation in visual areas when these same objects were subsequently viewed. Taken together, these results suggest that the object-representation systems of the ventral visual pathway are exploited for haptic object perception.

The Timecourse of Activation Within the Cortical Network Associated with Visual Imagery

“…(5A-C)). The region is similar to the location (similar Talairach coordinates) found in previous object processing tasks focusing on shape, the lateral occipital complex [35][36][37][38]. One possible explanation for the current result is that although shape processing is a component of both object inspection and mental rotation, the mental rotation condition relies more on shape information.…”

Cross-modal associations between vision, touch, and audition influence visual search through top-down attention, not bottom-up capture

“…Consistent with this suggestion, studies have demonstrated that the visual cortex of blind individuals is activated during tasks such as Braille reading (Cohen et al, 1997;Sadato et al, 1996) and haptic object recognition (Amedi, Raz, Azulay, Malach, & Zohary, 2010). Moreover, the existence of networks between vision and touch in normally sighted individuals is supported by neuroimaging studies; visual areas have been shown to be activated during tactile orientation discrimination (Sathian & Zangaladze, 2002;Sathian, Zangaladze, Epstein, & Grafton, 1999), haptic object recognition (Amedi, Jacobson, Hendler, Malach, & Zohary, 2002;Amedi et al, 2010;Deibert, Kraut, Kremen, & Hart, 1999;James, Humphrey, Gati, Servos, Menon, & Goodale, 2002;Pietrini et al, 2004), and Braille reading in sighted subjects following 5 days of complete visual deprivation (Merabet et al, 2008). Furthermore, there is behavioral evidence for the influence of tactile inputs on visual perception.…”

Analyzing Perceptual Representations of Complex, Parametrically-Defined Shapes Using MDS

“…In subsequent experiments, we will also allow participants to actively manipulate the objects such that they can analyze and compare them from all viewpoints. In addition, we are planning neuro-imaging experiments using fMRI which would allow us to show if visual and haptic exploration of the shell-shaped objects would activate the same brain areas and thus if the underlying map is processed by similar brain structures for both modalities [12]. Additionally, any differences in activating these brain structures could be correlated to modality.…”