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Archive for 16/09/2011

The mind’s touch

ScienceDaily has an item (here) reporting a paper by Damasio’s group, Seeing Touch is Correlated with Content-Specific Activity in Primary Somatosensory Cortex. They examined the touch equivalent of the mind’s eye.

“When asked to imagine the difference between touching a cold, slick piece of metal and the warm fur of a kitten, most people admit that they can literally ‘feel’ the two sensations in their ‘mind’s touch,’ ” said Meyer, the lead author of the study. “The same happened to our subjects when we showed them video clips of hands touching varied objects,” he said. “Our results show that ‘feeling with the mind’s touch’ activates the same parts of the brain that would respond to actual touch.”

Human brains capture and store physical sensations, and then replay them when prompted by viewing the corresponding visual image. “When you hold a thought in your mind about a particular object, that is not just mental fluff. It is rather a detailed memory file that is being revived in your brain,” Antonio Damasio said.

Here is the abstract:

There is increasing evidence to suggest that primary sensory cortices can become active in the absence of external stimulation in their respective modalities. This occurs, for example, when stimuli processed via one sensory modality imply features characteristic of a different modality; for instance, visual stimuli that imply touch have been observed to activate the primary somatosensory cortex (SI). In the present study, we addressed the question of whether such cross-modal activations are content specific. To this end, we investigated neural activity in the primary somatosensory cortex of subjects who observed human hands engaged in the haptic exploration of different everyday objects. Using multivariate pattern analysis of functional magnetic resonance imaging data, we were able to predict, based exclusively on the activity pattern in SI, which of several objects a subject saw being explored. Along with previous studies that found similar evidence for other modalities, our results suggest that primary sensory cortices represent information relevant for their modality even when this information enters the brain via a different sensory system.