Picower research finds unexpected activity in visual cortex

March 16, 2006

For years, neural activity in the brain's visual cortex was thought to have only one job: to create visual perceptions. A new study by researchers at MIT's Picower Institute for Learning and Memory shows that visual cortical activity can serve another purpose--connecting visual experience with non-visual events.

The study, slated to appear in the March 17 issue of Science, implies that sensory parts of the brain may be able to accomplish more complex tasks than previously imagined, according to co-authors Marshall G. Shuler, MIT research affiliate, and Mark F. Bear, professor of brain and cognitive sciences. The findings have implications for understanding how our brains imbue sensory experience with behavioral meaning.

Electrodes were implanted in the visual cortex of adult rats. Initially, as expected, their neurons responded only to light. However, as the animal repeatedly experienced a light stimulus with the delivery of a drop of water, the neuronal activity changed. And in many cases, the neuron continued to be active after the light was extinguished until the water reward was delivered.

The neuron's activity, the researchers said, was related to the anticipation of the reward. What's more, neurons continued to predict reward times associated with the light cues even in different situations. "This is a strong indication that learning was actually occurring in the visual cortex," Shuler said.

Brain activity corresponding to "reward timing has been observed in higher-order brain regions, but never in the primary visual cortex," Bear said. "No one would have expected to see it there because the visual cortex is thought to be a detector of the physical features of the environment, with responses limited to those features to ensure that sensory processing is reliable and reproducible."

"These neurons were not acting in response to what the stimuli were, but what they had come to mean," Shuler said.

The researchers are not sure whether the animal perceives this brain activity, but they plan to explore how it may guide appropriate behaviors.

"We are pretty optimistic we can uncover the mechanism" underlying this finding, Bear said. "There is a lot going on in the brain that we have been unaware of, studying anesthetized animals all these years."

This work was supported by the Howard Hughes Medical Institute.

Source: MIT

Explore further: Functioning brain follows famous sand pile model

Related Stories

Functioning brain follows famous sand pile model

June 22, 2015

One of the deep problems in understanding the brain is to understand how relatively simple computing units (the neurons), collectively perform extremely complex operations (thinking).

Method to reconstruct overt and covert speech

October 31, 2014

Can scientists read the mind, picking up inner thoughts? Interesting research has emerged in that direction. According to a report from New Scientist, researchers discuss their findings in converting brain activity into sounds ...

Addressing the human brain's big data challenge with BrainX3

March 4, 2015

The human brain generates massive amounts of data resulting from its intricate and complex spatiotemporal dynamics. Biophysical mechanisms underlying these processes are key to our understanding of brain function and disease. ...

Cell division, minus the cells

October 30, 2014

(Phys.org) —The process of cell division is central to life. The last stage, when two daughter cells split from each other, has fascinated scientists since the dawn of cell biology in the Victorian era. For just as long, ...

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

A cataclysmic event of a certain age

July 27, 2015

At the end of the Pleistocene period, approximately 12,800 years ago—give or take a few centuries—a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.

New blow for 'supersymmetry' physics theory

July 27, 2015

In a new blow for the futuristic "supersymmetry" theory of the universe's basic anatomy, experts reported fresh evidence Monday of subatomic activity consistent with the mainstream Standard Model of particle physics.

Dense star clusters shown to be binary black hole factories

July 29, 2015

The coalescence of two black holes—a very violent and exotic event—is one of the most sought-after observations of modern astronomy. But, as these mergers emit no light of any kind, finding such elusive events has been ...

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.