Biological basis of brain’s ability for rapid adaptation revealed

LONDON - When you detect an object flying at your head, you first move out of the way and then you try to determine what the object is. Your brain’s ability to rapidly switch from detecting an object moving in your direction to finding out what the object is through a phenomenon called adaptation.

Now, a new study details the biological basis of this ability for rapid adaptation: neurons located at the beginning of the brain’s sensory information pathway that changes their level of simultaneous firing.

This modification in neuron firing alters the nature of the information being relayed, which enhances the brain’s ability to discriminate between different sensations at the expense of degrading its ability to detect the sensations themselves.

“Previous studies have focused on how brain adaptation influences how much information from the outside world is being transmitted by the thalamus to the cortex, but we show that it is also important to focus on what information is being transmitted,” said Garrett Stanley of the Georgia Tech and Emory University.

For the experiments, Stanley and Wang moved a rat’s whisker to generate a sensory input. Moving whiskers at different speeds or at different angles produced sensory inputs that could be discriminated. This sensory experience is analogous to an individual moving a fingertip across a surface and perceiving the surface as smooth or rough.

While the whiskers were being moved, the researchers recorded neural signals simultaneously from different parts of the animal’s brain to determine what information was being transmitted.

“Neuroscientists know a lot about different parts of the brain, but we don’t know a lot about how they talk to each other. Recording how neurons are simultaneously communicating with each other in different parts of the brain and studying how the communication changes in different situations is a big step in this field,” said Stanley.

The results from the experiments showed that adaptation shifted neural activity from a state in which the animal was good at detecting the presence of a sensory input to a state in which the animal was better at discriminating between sensory inputs. In addition, adaptation enhanced the ability to discriminate between deflections of the whiskers in different angular directions, pointing to a general phenomenon.

The study also revealed that information the cortex receives from the thalamus is transformed as it travels through the pathway due to a change in the level of simultaneous firing of neurons in the thalamus.

The researchers found that the effect of adaptation on the synchrony of neurons in the thalamus was the key element in the shift between sensory input detection and discrimination.

The study has been published in the Nov. 21 advance online edition of the journal Nature Neuroscience. (ANI)