Affordances after spinal cord injury

Abstract

Spinal cord injury can cause cognitive impairments even when no cerebral lesion is appreciable. As patients are forced to explore the environment in a non-canonical position (i.e., seated on a wheelchair), a modified relation with space can explain motor-related cognitive differences compared to non-injured individuals. Peripersonal space is encoded in motor terms, that is, in relation to the representation of action abilities and is strictly related to the affordance of reachability. In turn, affordances, the action possibilities suggested by relevant properties of the environment, are related to the perceiver's peripersonal space and motor abilities. One might suppose that these motor-related cognitive abilities are compromised when an individual loses the ability to move. We shed light on this issue in 10 patients with paraplegia and 20 matched controls. All have been administered an affordances-related reachability judgement task adapted from Costantini, Ambrosini, Tieri, Sinigaglia, and Committeri (2010, Experimental Brain Research, 207, 95) and neuropsychological tests. Our findings demonstrate that patients and controls show the same level of accuracy in estimating the location of their peripersonal space boundaries, but only controls show the typical overestimation of reaching range. Secondly, patients show a higher variability in their judgements than controls. Importantly, this finding is related to the patients' ability to perform everyday tasks. Finally, patients are not faster in making their judgements on reachability in peripersonal space, while controls are. Our results suggest that not moving freely or as usual in the environment impact decoding of action-related properties even when the upper limbs are not compromised.

Seeing myself through my heart: Cortical processing of a single heartbeat speeds up self-face recognition

“…Specifically, we subtracted the individual PSE for each cardiac cycle phase (i.e., Systole and Diastole) from the morphing level (which varied from 0 to 100), thus obtaining an individual, continuous measure of deviation from PSE that ranged from 0 -PSE to 100 -PSE and took negative values for stimuli perceived as self, a value of 0 for the PSE, and positive values for stimuli perceived as other. Moreover, since we expected the self and other stimuli to have a different effect on decision processes, we added a categorical factor accounting for the type of stimulus relative to the individual PSE (see (Sedda et al, 2018)); this independent variable 'StimType' was obtained by coding negative PSE-scaled morphing level as self and positive ones as other. As these latter independent variables were condition-and participant-dependent, we assessed the effects of our experimental manipulations on the trial-level lnRTs by using a linear mixed-effect model analysis as implemented by the function lmer from the lme4 library (Bates, Mächler, Bolker, & Walker, 2015) in R (version 3.3.3; (RCoreTeam, 2017)).…”

Cognitive Training Improves Disconnected Limbs’ Mental Representation and Peripersonal Space after Spinal Cord Injury

“…Furthermore, de-afferentation and de-efferentation cause indirect plasticity processes in brain networks that extend beyond the sensorimotor system (for reviews see: [15][16][17]), and probably also contribute to cognitive changes. Experimental studies have indeed demonstrated changes in SCI people's representations of body [18][19][20][21], action [22][23][24] and space [20,[25][26][27], which are topographically organised and as such reflect the topography of the disconnected body parts.…”

Topographic mapping of the sensorimotor qualities of empathic reactivity: A psychophysiological study in people with spinal cord injuries

“…The sample size in this study may appear to be somewhat limited, but it is to be noted that this was influenced by the strict exclusion criteria which we adopted, that is, only paraplegics without sensorimotor functions in their legs and with no traumatic brain injury were recruited. Moreover, the number of participants in the study is in line with the sample size used in previous studies (Arrighi et al, 2011;Sedda et al, 2019). Another potential limitation might be in the number of subjective responses, as the participants did not give their evaluations in all of the trials, but only in a subset.…”