Karl Friston
(1959-)
Karl Friston is a British neuroscientist and theoretician at University College London. He is an authority on brain imaging and theoretical neuroscience, especially the use of physics-inspired statistical methods to model neuroimaging data and other random dynamical systems.
Friston is best known for the "free energy principle," a unified theory that suggests that all biological systems, including the brain, act to minimize free energy.
Friston's "free energy" has nothing to do with thermodynamic free energy, as defined by
J. Willard Gibbs, which is the energy available to do work in a system that is below thermal equilibrium (maximal disorder).
This minimization process applies to perception, action, and learning, and is essentially a form of active inference where systems try to make their sensory input predictable. In simpler terms, it's a way of describing how living things maintain their existence by actively reducing uncertainty about their environment.
1. Free Energy and Biological Systems:
• Free energy, in this context, is a mathematical quantity that provides a variational
bound on surprise or disorder.
• The free energy principle proposes that biological systems, from cells to brains, minimize this free energy, effectively acting to maintain a stable internal state despite external changes.
• This minimization occurs through perception (updating beliefs about the
environment) and action (changing the environment to fit predictions)
2. Bayesian Inference and Active Inference:
• The free energy principle is closely linked to Bayesian inference, where agents
make predictions based on prior knowledge and update these predictions based
on new sensory information.
•Active inference is a key aspect of the principle, where agents actively try to make
their sensory input more predictable by changing their actions. ,
For example, a tree growing towards the light is minimizing free energy by acting to
make the light (sensory input) more predictable.
3. Generative Models:
• The free energy principle also involves the concept of a generative model, which is
a model of the world that an agent uses to make predictions.
• By minimizing free energy, agents are essentially optimizing their internal
generative models to better reflect the structure of the environment.
Normal |
Teacher |
Scholar
|
