Adult male zebra finches are well-known for their ability to sing complex and precise songs to attract female mates. Unfortunately for them, they aren't born with a full song list and instead have to learn and practise their songs like any good musician. Most male zebra finches try to perfect their tunes by practising them thousands of times every day for more than three months before they are ready to try them out on a potential mate.
Their musical ability is important as the more precise they are in producing the exact pattern and timing of notes every single time the more likely they are to be seen as a suitable mate by a female.
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The research published in the journal Nature Communications monitored not only the process that a zebra finch went through while learning to sing but also the correlation to changing activity in their brain.
To learn something new, neurons in our brain need to form new connections and strengthen or weaken existing ones. It had been thought that new memories were stored through networks of connections that form between these neurons called synapses.
Neurons are unique as they have the ability to quickly change the electric current that flows in and out of them. By monitoring the sequence of spikes in these action potentials, scientists can measure what they think is the transfer of information from neurons as they pass along the network and indicate that the brain is learning.
One intrinsic property of the neurons is their ability to change the magnitude and strength of the currents that flow across their membranes.
By measuring subtle differences as the birds learned to sing each song through the long process of learning, practising and memorisation, the researchers were able to watch the brain changes of the bird as it learned.
They found that while baby birds were still learning their songs there was no correlation between the intrinsic cell properties across the birds. However, when they monitored different adult birds that had been raised by the same parents they found that they all had both similar songs and similar intrinsic neuron cell properties across their brains.
After monitoring the song learning process the researchers waited until the birds knew the songs well and then used a device to record the birdsong. They then played it back to the bird with a slight delay. Hearing their own song out of sync caused the bird to alter their song in a way that resembled stuttering in humans. The birds became stuck on certain notes and repeated patterns in their song in a different order.
This new finding implies that while learning and memory involve synapse changes as we have always believed, it seems to also involve changes to the intrinsic current flow properties of the brain cells involved. By understanding these intrinsic properties scientists may be able to tailor ways to help us to learn and remember things more efficiently as well as understand why some memories seem to fade over time.
