Brain's object recognition system activated by touch alone

May 28, 2009

Portions of the brain that activate when people view pictures of objects compared to scrambled images can also be activated by touch alone, confirms a new report published online on May 28th in Current Biology.

"That's the nub of the paper," said Harriet Allen of the University of Birmingham. "Part of the brain is for object processing irrespective of the sensory input coming in."

The discovery was made by studying a man, known as HJA, with a condition called visual agnosia after suffering a stroke that left a large bilateral lesion in part of the brain important for object recognition, specifically in the lateral occipital cortex (LO). As a result, although HJA was not blind, he could not process visual input normally; objects appeared to him as unrecognizable jumbles.

"It's difficult to imagine," Allen said. "If he looked at a pen, he might see lines, but he couldn't say which were the pen and which weren't." However, HJA could still recognize everyday objects by grasping them, they show.

In the study, the researchers had HJA and control participants observe pictures of objects and scrambled images while they were being scanned by (fMRI, which measures based on changes in blood flow). Participants were also scanned while they touched objects with one hand.

Within a subset of the regions found in control participants, HJA showed activity only for tactile objects, they report, suggesting that these regions are specifically involved in successful multi-modal recognition. The results show that activation of dorsal LO by tactile input is not secondary to . Rather, it can operate directly through the .

"Our data indicate, for the first time, that at least some regions in the LO can be activated normally from touch, even when input from ventral LO is lesioned and visual recognition is prevented," the researchers wrote. "This is consistent with estimates of effective connectivity from fMRI that have implied that there are direct connections between somatosensory cortex and LO."

When asked to recognize objects based on touch, early blind participants also show activation in similar brain regions, earlier studies have shown. However, they said, in those who are blind the LO may be recruited to process information differently than it does in sighted people. "Here we provide evidence for dorsal LO activation being driven, in part, directly from touch in a normally developed ."

Source: Cell Press (news : web)

Explore further: Probing Question: If a blind person gained sight, could they recognize objects previously touched?

Related Stories

How the brain copes with shifty eyeballs

April 18, 2007

Neurobiologists have pinpointed brain regions critical to one of the brain’s more remarkable feats—piecing together a continuous view of the world by integrating snippets of visual input from constantly moving eyes. Since ...

3-D brain centers pinpointed

August 1, 2007

In studies with monkeys, researchers have identified in detail the brain regions responsible for the unique ability of primates, including humans, to process visual 3D shapes to guide their sophisticated manipulation of objects.

Adult brain can change, study confirms

September 5, 2007

It is well established that a child's brain has a remarkable capacity for change, but controversy continues about the extent to which such plasticity exists in the adult human primary sensory cortex. Now, neuroscientists ...

Recommended for you

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

(PhysOrg.com) -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...

Quantum Theory May Explain Wishful Thinking

April 14, 2009

(PhysOrg.com) -- Humans don’t always make the most rational decisions. As studies have shown, even when logic and reasoning point in one direction, sometimes we chose the opposite route, motivated by personal bias or simply ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.