Who Decides in the Brain? How Decision-Making Processes
Are Influenced by Neurons
Tübingen neuroscientists have shown how decision-making
processes are influenced by neurons.
Whether in society or nature, decisions are often the
result of complex interactions between many factors. Because of this it is
usually difficult to determine how much weight the different factors have in
making a final decision. Neuroscientists face a similar problem since decisions
made by the brain always involve many neurons. Working in collaboration, the
University of Tübingen and the Max Planck Institute for Biological Cybernetics,
supported within the framework of the Bernstein Network, researchers lead by
CIN professor Matthias Bethge have now shown how the weight of individual
neurons in the decision-making process can be reconstructed despite
interdependencies between the neurons.
When we see a person on the other side of the street who
looks like an old friend, the informational input enters the brain via many
sensory neurons. But which of these neurons are crucial in passing on the
relevant information to higher brain areas, which will decide who the person is
and whether to wave and say 'hello'? A research group lead by Matthias Bethge
has now developed an equation that allows them to calculate to what degree a
given individual sensory neuron is involved in the decision process.
To approach this question, researchers have so far
considered the information about the final decision that an individual sensory
neuron carries. Just as an individual is considered suspicious if he or she is
found to have insider information about a crime, those sensory neurons whose
activity contains information about the eventual decision are presumed to have
played a role in reaching the final decision. The problem with this approach is
that neurons -- much like people -- are constantly communicating with each
other. A neuron which itself is not involved in the decision may simply have
received this information from a neighboring neuron and "joined in"
the conversation. Actually, the neighboring cell sends out the crucial signal
transmitted to the higher decision areas in the brain.
The new formula that has been developed by scientists
addresses this by accounting not just for the information in the activity of
any one neuron but also for the communication that takes place between them.
This formula will now be used to determine whether only a few neurons that
carry a lot of information are involved in the brain's decision process, or
whether the information contained in very many neurons gets combined. In
particular, it will be possible to address the more fundamental question: In which
decisions does the brain use information in an optimal way, and for which
decisions is its processing suboptimal?
Source: sciencedaily
Image Source: http://www.sxc.hu/photo/1043922
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