Evidence of memories in the brain of songbirds

When a manhole hears a new melody from a member of the same species, the gene expression in its brain changes surprisingly, the researchers report. Turning on and off thousands of genes after a bird listens to a melody gives a new picture of memory in the brain of songbirds.

This finding, published this month in the Proceedings of the National Academy of Sciences, is a surprise, said lead researcher David Clayton, professor of cell biology and development at the University of Illinois. . He and his colleagues did not expect the participation of many such genes, and argued that any changes in gene activity after the bird heard a new melody would quickly dissipate.

New experiments have found three types of gene expression in the brain . One is when the bird sits alone in silence. The second form appears quickly after the bird hears a recorded melody - but only if the melody is new to the bird. The third form appeared 24 hours later, when the melody became familiar.

Clayton said: 'I can tell if a bird has heard a certain melody before just by looking at the molecular experiment'.

David Clayton and colleagues observed a cycle of gene activity in the fragile bird's brain after hearing an unfamiliar stage. (Photo: L. Brian Stauffer, U. of I. News Brueau)

In the study, each bird was silently isolated overnight before it was heard a new tune. This melody is repeated every 10 seconds for 3 hours.

Clayton said: 'The most important thing in its life is the song of another bird of the same species'.

'And we found that 24 hours later, the bird's brain still tried to understand what it was listening to.'

New research explores gene activity in the brain. Using microscopic DNA analysis, the researchers measured changes in RNAs in information in the anterior part of the manhole when exposed to the new melody. These messenger RNAs are the template that allows cells to decode each gene into proteins. The reduction or increase in the amount of messenger RNA in brain cells after stimulation gives clues to the brain's response.

Some genes are enhanced within 30 minutes of new tone exposure, including metabolic factors involved in the activity of other genes. Some genes are reduced, including coding for iron-led proteins, allowing iron to flow into the cell. This may be a way in which the brain reduces its response to strong stimulation, protecting itself from disturbance.

Clayton said: 'Whenever something unexpected or strange happens, such as a new melody of a neighbor bird, it will alter the neural network of the bird listening to the melody. there. Therefore, the whole system must adapt, make some changes'.

Conversely, if the system is completely capable of resisting disturbances or stimuli, no memories are formed.

24 hours after the initial stimulation, the cycle of activating genes is completely different from the first one, regardless of whether the bird listens to the melody on the second day. Modified or reduced genes returned to the original boundary, and a new gene network was compromised. The main focus of this new network is the control of energy exchange. This shows that there are still many things happening in the bird's brain.

Clayton concluded: 'This bird only experiences this for one day, and the next day its brain is in a completely different state. It is still in a state of 'number setting' and processing information. The sound it heard still reflected and resounded somewhere. '

Refer:

1. Shu Dong, Kirstin L. Replogle, Linda Hasadsri, Brian S. Imai, Peter M. Yau, Sandra Rodriguez-Zas, Bruce R. Southey, Jonathan V. Sweedler, and David F. Clayton.Discrete molecular states in the brain accompany changing responses to a vocal signal.PNAS, published 18 June 2009, DOI: 10.1073 / pnas.0812998106