Massive somatic deafferentation and motor deefferentation of the lower part of the body impair its visual recognition: a psychophysical study of patients with spinal cord injury

Abstract

Embodied cognition theories postulate that perceiving and understanding the body states of other individuals are underpinned by the neural structures activated during first-hand experience of the same states. This suggests that one's own sensorimotor system may be used to identify the actions and sensations of others. Virtual and real brain lesion studies show that visual processing of body action and body form relies upon neural activity in the ventral premotor and the extrastriate body areas, respectively. We explored whether visual body perception may also be altered in the absence of damage to the above cortical regions by testing healthy controls and spinal cord injury (SCI) patients whose brain was unable to receive somatic information from and send motor commands to the lower limbs. Participants performed tasks investigating the ability to visually discriminate changes in the form or action of body parts affected by somatosensory and motor disconnection. SCI patients showed a specific, cross-modal deficit in the visual recognition of the disconnected lower body parts. This deficit affected both body action and body form perception, hinting at a pervasive influence of ongoing body signals on the brain network dedicated to visual body processing. Testing SCI patients who did or did not practise sports allowed us to test the influence of motor practice on visual body recognition. We found better upper body action recognition in sport-practising SCI patients, indicating that motor practice is useful for maintaining visual representation of actions after deafferentation and deefferentation. This may be a potential resource to be exploited for rehabilitation.

Primary somatosensory cortex necessary for the perception of weight from other people's action: A continuous theta-burst TMS experiment

“…In conclusion, earlier evidence supported the claim that somatosensory cortices are activated not only during action execution, but also during perception of others’ actions, but whether such activation of SI is necessary to efficiently judge the somatosensory aspects of the actions of others remained unclear (Gazzola et al, 2007b, Pernigo et al, 2012, Vannuscorps and Caramazza, 2015). Indirect evidence came from sensory neuropathy patients that lack a sense of touch on their own body.…”

Rubber hand illusion induced by touching the face ipsilaterally to a deprived hand: evidence for plastic “somatotopic” remapping in tetraplegics

“…However, no relationship between the indices of RHI and the results of the personality and susceptibility tests was found in our sample, suggesting that studies with a larger sample are necessary to demonstrate whether the absence of evidence really means that this relationship does not exist. In a previous study on SCI subjects (Pernigo et al, 2012), we demonstrated that practicing sport was useful in terms of strengthening the visual representation of upper limb body parts and contrasting the effects of somatosensory and motor deprivation. As a result we reasoned that in this study the degree of functional autonomy (which is mainly linked to the extent of the lesion) might influence the effects of the RHI.…”

Vicarious motor activation during action perception: beyond correlational evidence

“…Motor experts present superior perceptual abilities in the prediction of others' actions (Abernethy et al, 2008; Aglioti et al, 2008) and short-term action execution training improves perception of full (Hecht et al, 2001; Urgesi et al, 2012) and point-light (Casile and Giese, 2006) displays of the same action even if no visual feedback is provided during the execution phase. On the other hand, non-use of specific body parts, following massive deafferentation of lower limbs in spinal cord injury patients, leads to impaired recognition of their movements depicted in static images (Pernigo et al, 2012) and point-light (Arrighi et al, 2011) displays.…”