Spatial coding of visual and somatic sensory information in body-centred coordinates.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Sensory Integration

Background:

• Sensory systems utilize diverse spatial coordinate frames, necessitating cross-modal integration and transformations for unified spatial perception.
• Multimodal neurons employing non-retinal, body-centered reference frames have been identified in primate posterior parietal and frontal cortices.

Purpose of the Study:

• To identify human brain regions involved in coding spatial positions of visual and somatic stimuli using body-centered coordinates.
• To investigate the neural mechanisms underlying multimodal sensory integration and spatial representation in humans.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to observe brain activity.
• Participants performed tasks requiring them to determine the left or right position of visual or tactile stimuli relative to their body's mid-sagittal plane.
• A control task with similar stimuli and responses, but without body-centered coding, was used for comparison.

Main Results:

• A bilateral fronto-parietal network, more prominent in the right hemisphere, was activated during body-centered coding for both visual and somatic stimuli.
• Activated regions included the posterior parietal cortex (intraparietal sulcus) and frontal cortex (precentral sulcus, superior frontal sulci, inferior frontal gyrus, medial superior frontal gyrus).
• The occipito-temporal junction and extrastriate regions showed enhanced bilateral activation for visual stimuli during body-centered coding.

Conclusions:

• Human posterior parietal and frontal regions, analogous to those in monkeys, support multimodal spatial representations in body-centered coordinates.
• This research provides the first evidence of such processing networks in the human brain, advancing our understanding of spatial cognition.