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July 25, 2007

Elizabeth Torres: Three building blocks of the mind to autonomously control the body

Elizabeth Torres














We had a wonderful talk today from Dr. Elizabeth Torres who is currently at CalTech.


We propose three necessary components for autonomous behavior that any biological organism with sensors, a nervous system subject to the inevitable sensory-processing internal delays and equipped with memories should have. The first component deals with spatio-temporal disparities between the internal and the external mediums of the organism to facilitate comparisons of signals that may be misaligned in space and time. The second component evaluates the similarities between current and old (memories) information to select a course of action (storing a new memory from scratch, using an old memory as it is, or updating an old memory to turn it into a new one as part of a family). The third component regulates the level of relevance for storage, retrieval and update of memories according to the consequences that a given situation my have for the survival and reproduction of the organism.

We provide an example of how these three blocks manifest in primates within the domain of voluntary arm movements. As other systems in the brain, the sub-systems involved in these autonomous behaviors have to deal with sensory-motor maps and transformations involving disparate spatio-temporal representations, internal sensory-processing delays and memories (in the motor domain). Thus these subsystems need to store, retrieve and update memories, which (in primates) we define as associations between the allocentric representation of internal delays (anchored to an early sensory receptor like those in the retina) and a given set of external contextual cues according to their relevance (consequence). We show empirical data from humans and monkeys that strongly suggest that in primates, given a situation such binding computation can be allocentric encoded retinotopically independent of body motions. This evidence changes the way in which we currently think of episodic memory and provides a fresh look at how our conscious notion of the passage of time may have come about.