Neural modifications in lower limb amputation: an fMRI study on action and non-action oriented body representations

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Limb amputation disrupts sensorimotor and visual input, impacting action-oriented (body schema) and non-action oriented body representations.
• The precise neural mechanisms underlying these representational changes post-amputation remain incompletely understood.

Purpose of the Study:

• To investigate the neural correlates of body representations in individuals with left lower limb amputation (LLA) compared to healthy controls (HC).
• To examine how mental rotation tasks involving body parts and objects reveal differences in brain activation patterns.

Main Methods:

• Event-related functional magnetic resonance imaging (fMRI) was employed.
• Nine individuals with LLA and eleven age-matched HC performed mental rotation of body parts (hand, foot, eye) and objects (rear-view mirror).

Main Results:

• While performance was comparable between LLA and HC groups, distinct brain activation patterns emerged.
• Reduced activation in the bilateral intraparietal sulcus was observed in LLA.
• Increased activation in the bilateral anterior insula, left fusiform body area (EBA), left precentral gyrus, left supplementary motor area, and right inferior occipital gyrus was noted in LLA during left-sided mental rotation tasks.
• The left EBA showed differential activation between foot and eye mental rotation in LLA, unlike in HC.

Conclusions:

• Left lower limb amputation leads to modifications within the body representation network.
• These neural alterations occur even in the absence of significant behavioral deficits, suggesting a complex adaptation of the brain.