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Forehead topography in the primary somatosensory cortex. All annotations are as in Figure 2. Distances in the intact hemisphere are plotted in pink and deprived hemisphere in red. # strong positive trend; * p < .05; *** p < .001; coloured asterisk's indicate values are significantly different from zero.
Source publication
Cortical remapping after hand loss in the primary somatosensory cortex (S1) is thought to be predominantly dictated by cortical proximity, with adjacent body parts remapping into the deprived area. Traditionally, this remapping has been characterised by changes in the lip representation, which is assumed to be the immediate neighbour of the hand ba...
Contexts in source publication
Context 1
... the neighbour to the hand -the forehead -would reorganise after limb loss in amputees, as hypothesised by traditional theories 39 . Again, we found no significant evidence for cortical remapping of the neighbouring forehead in amputees when assessing changes in = 0.758). As the forehead's CoG tended to be located above the hand-face border (see Fig. 4A), these results indicate a significant shift of forehead activity away from the deprived hand ROI. This is further supported by a significant decrease of surface area coverage for the forehead in the deprived hand ROI when compared to controls (U = 381.000, p < .001, d = 1.069), which was significantly different from zero (W = 19.000, ...
Context 2
... indicate a significant shift of forehead activity away from the deprived hand ROI. This is further supported by a significant decrease of surface area coverage for the forehead in the deprived hand ROI when compared to controls (U = 381.000, p < .001, d = 1.069), which was significantly different from zero (W = 19.000, p < .001, d = -0.835; Fig. 4C). Remapping of the cortical neighbour in one-handers, therefore, manifests in a shifting away of the upper face from the deprived hand area, possibly due to increases in activity of other facial movements, e.g., lips. ...
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Cortical remapping after hand loss in the primary somatosensory cortex (S1) is thought to be predominantly dictated by cortical proximity, with adjacent body parts remapping into the deprived area. Traditionally, this remapping has been characterised by changes in the lip representation, which is assumed to be the immediate neighbour of the hand ba...
The objective of the work was to realize a preliminary study of proof-of-concept to evaluate emotions using thermographic images and blood perfusion algorithm; the images were obtained for baseline and positive and negative valence according to the protocol of the Geneva Affective Picture Database. The blood perfusion algorithm is based on the heat...
In this work, a preliminary study of proof-of-concept was conducted to evaluate the performance of the thermographic and blood perfusion data when emotions of positive and negative valence are applied, where the blood perfusion data are obtained from the thermographic data. The images were obtained for baseline, positive, and negative valence accor...
Citations
... The protocols were approved by the NHS National Research Ethics Service approval (18/LO/0474) for the body and face tasks and UCL Research Ethics Committee (REC: 12921/001) for the finger task and were performed in accordance with the Declaration of Helsinki. The face and hand datasets were recently used for other purposes (Kieliba et al., 2021;Root et al., 2021). ...
... For the face task, participants were instructed to perform one of four movements: raise the eyebrows (i.e., forehead), flare nostrils (i.e., nose), puckering lips (i.e., lips), and tap the tongue to the roof of the mouth (i.e., tongue). Two additional conditions involving the left and right thumbs were also included but will not be further described as they were not included in the main analysis (see Root et al., 2021 for analysis of these conditions). ...
The homunculus in primary somatosensory cortex (S1) is famous for its body part selectivity, but this dominant feature may eclipse other representational features, e.g., information content, also relevant for S1 organization. Using multivariate fMRI analysis, we ask whether body part information content can be identified in S1 beyond its primary region. Throughout S1, we identify significant representational dissimilarities between body parts but also subparts in distant non-primary regions (e.g., between the hand and the lips in the foot region and between different face parts in the foot region). Two movements performed by one body part (e.g., the hand) could also be dissociated well beyond its primary region (e.g., in the foot and face regions), even within Brodmann area 3b. Our results demonstrate that information content is more distributed across S1 than selectivity maps suggest. This finding reveals underlying information contents in S1 that could be harnessed for rehabilitation and brain-machine interfaces.
... This includes body-parts that have not been considered to invade the missing hand cortical area, such as the feet, trunk, and neck, in some cases even contralateral to the missing hand [3,[15][16][17][18][19]. These reports, as well as recent fMRI studies that dispute the existence of a large-scale S1 facial remapping post-amputation in humans [20][21][22][23], challenge the perceptual remapping hypothesis. ...
... To confirm that appropriate movements were made at the instructed times, task performance was visually monitored online for both tasks. These datasets were recently used for other purposes (i.e., body task used as functional localiser in [32] and face task analysed in more detail in [21]), but the body dataset was not used before to assess remapping. ...
... 3T MRI data acquisition and pre-processing followed standard procedures, as detailed in the Supplemental Material (see also [21,32]). Functional data was analysed in individual's native functional space and pre-processed using FSL-FEAT (v.6.00). Voxel-wise General Linear Model (GLM) was applied to the data using FEAT to obtain statistical parametric maps for each movement. ...
Background
Some amputees have been prominently reported to perceive touch applied to their face as coming from their phantom hand. These referred sensations have been classically interpreted as the perceptual correlate of cortical remapping of the face into the neighbouring missing- hand territory in primary somatosensory cortex (S1). We investigated whether referred sensations reports are associated with S1 remapping or can instead be attributed to demand characteristics (e.g., compliance, expectation, and suggestion), which were uncontrolled in previous studies.
Methods
Unilateral upper-limb amputees (N=18), congenital one-handers (N=19), and two-handers (N=20) were repeatedly stimulated with PC-controlled vibrations on ten body-parts and asked to report on each trial the occurrence of any concurrent sensations on their hand(s). To further manipulate expectations, we gave participants the suggestion that some of these vibrations had a higher probability to evoke referred sensations. To evaluate remapping, we analysed fMRI data in S1 from two tasks involving movement of facial and whole-body parts, using univariate and multivariate approaches.
Results
The frequency and distribution of reported referred sensations were similar across groups, with higher frequencies in the high expectancy condition. In amputees, referred sensations were evoked by stimulation of multiple body-parts and reported in both the intact and phantom hand. The group profiles for referred sensations reports were not consistent with the observed patterns of S1 remapping.
Conclusions
These findings weaken the interpretation of referred sensations as a perceptual consequence of post-amputation S1 remapping and reveal the need to account for demand characteristics when evaluating anomalous perceptual and germane phenomena.
... The protocols were approved by the NHS National Research Ethics Service approval (18/LO/0474) for the body and face tasks and UCL Research Ethics Committee (REC: 12921/001) for the finger task and were performed in accordance with the Declaration of Helsinki. The face and hand datasets were recently used for other purposes (Kieliba et al., 2021;Root et al., 2021). ...
... For the face task, participants were instructed to perform one of four movements: raise the eyebrows (i.e., forehead), flare nostrils (i.e., nose), puckering lips (i.e., lips), and tap the tongue to the roof of the mouth (i.e., tongue). Two additional conditions involving the left and right thumbs were also included but will not be further described as they were not included in the main analysis (see Root et al., 2021 for analysis of these conditions). ...
The homunculus in primary somatosensory cortex (S1) is famous for its body part selectivity, but this dominant feature may eclipse other representational features, e.g., information content, also relevant for S1 organization. Using multivariate fMRI analysis, we ask whether body part information content can be identified in S1 beyond its primary region. Throughout S1, we identify significant representational dissimilarities between body parts but also subparts in distant non-primary regions (e.g., between the hand and the lips in the foot region and between different face parts in the foot region). Two movements performed by one body part (e.g., the hand) could also be dissociated well beyond its primary region (e.g., in the foot and face regions), even within Brodmann area 3b. Our results demonstrate that information content is more distributed across S1 than selectivity maps suggest. This finding reveals underlying information contents in S1 that could be harnessed for rehabilitation and brain-machine interfaces.
