Final Report Summary - C - LEARNING (Learning context dependent behavior: neural and synaptic mechanisms)
Summary description of the project objectives
Objective 1:
Develop a general theoretical framework for learning context dependent behavior.
The first objective of the project is to develop a general theoretical framework to model the learning of context dependent behavior, i. e. situations in which the reaction to a given stimulus is not determined by the stimulus alone, but by the overall context in which the stimulus appears.
Objective 2: Develop a novel model of learning context-dependent encoding of emotional value.
The second objective of the project is to apply our theoretical framework to a particular experimental paradigm in order to test theoretical predictions. The experimental paradigm in question is a context-dependent trace-conditioning task studied by means of monkey electrophysiology in the Salzman lab at Columbia University.
-description of the work performed since the beginning of the project
Objective 1: We have analyzed biophysically realistic models of synaptic plasticity in order to identify substrates of the learning of context dependent behavior.
Objective 2: We have analyzed the behavioral and neural data obtained from the experiments performed in the Salzman lab.
-description of the main results achieved
Objective 1: a general mechanism for the learning of context dependent behavior has been identified. This mechanism is based on the fundamental ability of populations of synapses to encode temporal contiguity between events. We have analyzed in detail this synaptic coding of temporal contiguity and showed that it is a fundamental consequence of a basic property of synapses, namely the fact that individual synapses possess a finite number of states. We have therefore related the capacity to learn context-dependent behavior to a fundamental biophysical property of the synaptic connections.
Objective 2: we have shown that non-human primates develop mental states corresponding to different contexts in which a stimulus can appear. Using population decoding methods, we have identified neural substrates of these mental states in the orbito-frontal cortex, the anterior-cingulate context and the amygdala, and related the corresponding neural activity to behavior. Importantly, our results demonstrate that current context is encoded in both prefrontal, cognitive areas, and limbic areas such as the amygdala, that represent emotions.
-potential impact and use of the final results
Objective 1: We have shown that the synaptic encoding of temporal contiguity, the mechanism underlying context dependent-behavior, is an extremely general property of synaptic plasticity. As such, we expect that it underlies a number of phenomena other than context-dependent behavior. In particular it might underlie prospective behavior, the learning of visual invariances of three-dimensional objects, and in general decision making in complex, stochastic environments. The theoretical results of this project will therefore serve as a basis for a number of future studies.
Objective 2: Our analyses of experimental data have established that non-human primates can acquire complex cognitive behaviors comparable to those performed by humans. The neural correlates of context-dependent behavior that we have identified will serve as a guide for interpreting non-invasive imaging data recorded in humans.
-potential transfer of knowledge. Having spent 2 years at Columbia University, New York, during the outgoing phase of the project, the fellow has returned to the Ecole Normale Superieure in Paris, France. The return phase was terminated early as the fellow has obtained a permanent position as a CNRS researcher at the return host, the Ecole Normale Superieure. Despite the early termination the transfer of knowledge is taking place as planned. The fellow is collaborating with Dr. Vincent Hakim on the theoretical aspects of the project. As planned in the research proposal, a collaboration is also under way with Dr Etienne Koechlin, who studies context-dependent behavior in humans. The aim of that collaboration is to test theoretical predictions from the model developed during the outgoing phase and transfer to humans data-analysis techniques developed on primate data.
Objective 1:
Develop a general theoretical framework for learning context dependent behavior.
The first objective of the project is to develop a general theoretical framework to model the learning of context dependent behavior, i. e. situations in which the reaction to a given stimulus is not determined by the stimulus alone, but by the overall context in which the stimulus appears.
Objective 2: Develop a novel model of learning context-dependent encoding of emotional value.
The second objective of the project is to apply our theoretical framework to a particular experimental paradigm in order to test theoretical predictions. The experimental paradigm in question is a context-dependent trace-conditioning task studied by means of monkey electrophysiology in the Salzman lab at Columbia University.
-description of the work performed since the beginning of the project
Objective 1: We have analyzed biophysically realistic models of synaptic plasticity in order to identify substrates of the learning of context dependent behavior.
Objective 2: We have analyzed the behavioral and neural data obtained from the experiments performed in the Salzman lab.
-description of the main results achieved
Objective 1: a general mechanism for the learning of context dependent behavior has been identified. This mechanism is based on the fundamental ability of populations of synapses to encode temporal contiguity between events. We have analyzed in detail this synaptic coding of temporal contiguity and showed that it is a fundamental consequence of a basic property of synapses, namely the fact that individual synapses possess a finite number of states. We have therefore related the capacity to learn context-dependent behavior to a fundamental biophysical property of the synaptic connections.
Objective 2: we have shown that non-human primates develop mental states corresponding to different contexts in which a stimulus can appear. Using population decoding methods, we have identified neural substrates of these mental states in the orbito-frontal cortex, the anterior-cingulate context and the amygdala, and related the corresponding neural activity to behavior. Importantly, our results demonstrate that current context is encoded in both prefrontal, cognitive areas, and limbic areas such as the amygdala, that represent emotions.
-potential impact and use of the final results
Objective 1: We have shown that the synaptic encoding of temporal contiguity, the mechanism underlying context dependent-behavior, is an extremely general property of synaptic plasticity. As such, we expect that it underlies a number of phenomena other than context-dependent behavior. In particular it might underlie prospective behavior, the learning of visual invariances of three-dimensional objects, and in general decision making in complex, stochastic environments. The theoretical results of this project will therefore serve as a basis for a number of future studies.
Objective 2: Our analyses of experimental data have established that non-human primates can acquire complex cognitive behaviors comparable to those performed by humans. The neural correlates of context-dependent behavior that we have identified will serve as a guide for interpreting non-invasive imaging data recorded in humans.
-potential transfer of knowledge. Having spent 2 years at Columbia University, New York, during the outgoing phase of the project, the fellow has returned to the Ecole Normale Superieure in Paris, France. The return phase was terminated early as the fellow has obtained a permanent position as a CNRS researcher at the return host, the Ecole Normale Superieure. Despite the early termination the transfer of knowledge is taking place as planned. The fellow is collaborating with Dr. Vincent Hakim on the theoretical aspects of the project. As planned in the research proposal, a collaboration is also under way with Dr Etienne Koechlin, who studies context-dependent behavior in humans. The aim of that collaboration is to test theoretical predictions from the model developed during the outgoing phase and transfer to humans data-analysis techniques developed on primate data.