Umeå physiologists describe a new principle for information coding in the nervous system

How does the nervous system code, transmit, and process the information that steers our behaviour? Ronald S. Johansson’s research team at Umeå University in Sweden is now publishing its discovery of a new principle for this.

The prevailing view is that information is coded and transmitted by variations in the number of nerve impulses per time unit in the fibres of the nerve cells, that is, as a frequency code.

Johansson’s research team at the Section for Physiology present in the journal Nature Neuroscience a new principle for how information is coded and transmitted in the nervous system. When we manipulate objects, the brain reacts more quickly to the form of the objects and the direction of the contact forces than would be possible with frequency coding of information from the sensory organs of the fingertips. Frequency coding would require that the individual nerve fibre would have time to signal at least two impulses, and to interpret the message the brain needs to monitor signal traffic for a considerable period of time.

The team of scientists is now demonstrating that the information is effectively coded on the basis of the very first nerve impulse occurring in the nerve fibres that are excited when the fingertip contacts objects. The time gap between the first nerve impulses that occur in the signaling nerve fibres convey the information more rapidly that frequency codes­-and fast enough to explain the role of the tactile sense in steering the fine motor movements of the hand.

In experiments carried out on conscious volunteers, signals were registered in individual nerve fibres running from the tactile organs of the fingertips to the spinal cord and brain stem.

In August 2003, Roland S. Johansson published an article in Nature together with a Canadian visiting researcher. It dealt with how the brain can understand the actions of other individuals.

In the new article in Nature Neuroscience, appearing online in January, his co-author is one of his previous doctoral candidates, Ingvars Birznieks, who defended his thesis in 2003 at the Section for Physiology.