Preserved Object Weight Processing after Bilateral Lateral Occipital Complex Lesions

Abstract

Object interaction requires knowledge of the weight of an object, as well as its shape. The lateral occipital complex (LOC), an area within the ventral visual pathway, is well known to be critically involved in processing visual shape information. Recently, however, LOC has also been implicated in coding object weight before grasping-a result that is surprising because weight is a nonvisual object property that is more relevant for motor interaction than visual perception. Here, we examined the causal role of LOC in perceiving heaviness and in determining appropriate fingertip forces during object lifting. We studied perceptions of heaviness and lifting behavior in a neuropsychological patient (M.C.) who has large bilateral occipitotemporal lesions that include LOC. We compared the patient's performance to a group of 18 neurologically healthy age-matched controls. Participants were asked to lift and report the perceived heaviness of a set of equally weighted spherical objects of various sizes-stimuli which typically induce the size-weight illusion, in which the smaller objects feel heavier than the larger objects despite having identical mass. Despite her ventral stream lesions, M.C. experienced a robust size-weight illusion induced by visual cues to object volume, and the magnitude of the illusion in M.C. was comparable to age-matched controls. Similarly, M.C. evinced predictive fingertip force scaling to visual size cues during her initial lifts of the objects that were well within the normal range. These single-case neuropsychological findings suggest that LOC is unlikely to play a causal role in computing object weight.

The size-weight illusion in visual form agnosic patient DF

“…Dijkerman et al (2004) found that patient SB, who has visual agnosia as a consequence of damage sustained at 3 years old, experiences no visual size-weight illusion but does experience a kinaesthetic size-weight illusion. In contrast, Buckingham, Holler, Michelakakis, & Snow (2018) found that patient MC -who also sustained damage to the visual ventral stream -experiences a visual size-weight illusion that is statistically indistinguishable from that of controls. Patient MC's size-weight illusion was, however, smaller than that of 10/12 of Buckingham, Holler, Michelakakis, & Snow's (2018) controls.…”

“…In contrast, Buckingham, Holler, Michelakakis, & Snow (2018) found that patient MC -who also sustained damage to the visual ventral stream -experiences a visual size-weight illusion that is statistically indistinguishable from that of controls. Patient MC's size-weight illusion was, however, smaller than that of 10/12 of Buckingham, Holler, Michelakakis, & Snow's (2018) controls. This reduced size-weight illusion magnitude may represent a modest deficit in MC, which Buckingham, Holler, Michelakakis, & Snow (2018) may have been unable to detect due to low statistical power (Figure 2a).…”

Effects of TMS over the anterior intraparietal area on anticipatory fingertip force scaling and the size-weight illusion

“…Previous clinical evidence suggested a possible role for the posterior parietal cortex, but results were mixed (Li et al, 2007, 2011). It seems likely instead that other areas are more involved in the SWI, such as the ventral premotor cortex (Chouinard et al, 2009) or the lateral occipital cortex (Gallivan et al, 2014), although lesions this latter area did not seem to affect the SWI (Buckingham et al, 2018).…”

“…This was an interesting result, since this area is also known to be involved in visual as well as haptic object perception (Amedi, Jacobson, Hendler, Malach, & Zohary, 2002; Amedi, Malach, Hendler, Peled, & Zohary, 2001) and especially involved in the representation of object shape (Kourtzi & Kanwisher, 2001). However, it was recently shown that bilateral lesions to the lateral occipital cortex did not affect perception of the SWI in a stroke patient (Buckingham, Holler, Michelakakis, & Snow, 2018), leaving it unclear whether this region has a causal role in weight perception.…”

Retrospective study of late radiation-induced damages after focal radiotherapy for childhood brain tumors

“…Significant associations with PP scores were also found for Occipital Mid L and Temporal Mid L doses. Indeed the first area has an important role in coding object weight prior to grasping [43] and in object-directed action [44]. The second area is involved in many functions among which, motion [45] and grasp observation [46] and probably also in self-grasp observation, by a mechanism of mirroring.…”