Examining central biases in somatosensory localization: Evidence from brain-damaged individuals

• Published in: Neuropsychologia 2022-02, Vol.166, p.108137-108137, Article 108137
• Main Authors: Ambron, Elisabetta, Liu, Yuqi, Grzenda, Michael, Medina, Jared
• Format: Article
• Language: English
• Subjects: Bias; Brain; Centering; Hand; Humans; Physical Stimulation; Tactile detection; Tactile localization; Touch; Touch Perception; Uncertainty; Weighting
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2021.108137

How does the brain localize touch under conditions of uncertainty caused by brain damage? By testing single cases, previous work found mislocalization of touch toward the center of the hand. We investigated whether such central bias changes as a function of uncertainty in somatosensory system. Fifty-one brain-damaged individuals were presented with a tactile detection task to establish their tactile threshold, and a tactile localization task in which they localized suprathreshold stimuli presented at different locations on the hand. We predicted that with increased somatosensory uncertainty, indexed by higher detection thresholds, participants would more likely to localize the stimuli toward the center of the hand. Consistent with this prediction, participants’ localization errors were biased towards the center of the hand and, importantly, this bias increased as detection threshold increased. These findings provide evidence that instead of showing random errors, uncertainty leads to systematic localization errors toward the center of the hand or the center of the stimulus distribution, which overlapped in the present study. We discuss these findings under different frameworks as potential mechanisms to explain biases in tactile localization subsequent to brain damage. •We examined biases in tactile localization in individuals with brain damage.•After brain damage, individuals tend to localize touch toward the center of the hand.•These central biases increase with tactile detection threshold.•These findings demonstrate increased central bias with higher somatosensory uncertainty.•The brain might rely on body-part category information or the distribution of tactile stimuli under uncertainty.