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English Program 2008/09 The search for general laws: General Psychology Classical conditioning serving as an example for the investigation of the basic mechanisms of learning Classical Conditioning Conditioning Typ S „Signal learning“ Iwan Petrowitsch Pawlow (1849-1936) Unconditioned Stimulus UCS UR Unconditioned Reaction Conditioned Stimulus Conditioned Stimulus CS CS CR Unconditioned Reaction UCS Unconditioned Stimulus UR Conditioned Reaction Inhibition: Conditioned Stimulus CS CR CS CR Unconditioned Reaction Lack of Reinforcement results in fading of the reaction Inhibiton is an active process Reaction CS Trial Spontaneous Recovery John B. Watson (1878-1950) Hebb postulate for learning (1949): Facilitation of synaptic transmission is the neuronal basis of learning Bliss & Lomo (1973): LTP First observation of facilitation of synaptic transmission after high frequency stimulation of the presynaptic neuron. Long-term potentiation LTP remains stable for many weeks NMDA receptor [N-methyl-D-aspartate receptor] Evidence that LTP is involved in learning: LTP occurs at synapses participating in learning Conditioning produces LTP-like changes Mutant mice with little LTP have learning difficulties LTP triggers structural changes: • Increased number of synapses • Increased size of synapses • Increased number of NMDA receptors E.R. Kandel (2001): The molecular biology of memory storage. A dialog between genes and synapses. E.R. Kandel (2001): The molecular biology of memory storage. A dialog between genes and synapses. E. R. Kandel Nobelpreis 2000 The molecular biology of memory storage: A dialogue between gens and synapses. [Science 2001] Sipho-System: 24 sensory neurons connected with 6 motoneurons controlling the withdrawl of the gill Tissue cultures for simple learning networks Shorterm memory: Increasend release of transmitter Growth takes place on activated neurons only Longterm memory: Sprouting of new synaptic connections Neuronal Plasticity: Cortical projection areas change as a result of learning processes [M. M. Merzenich 1990] New connections are seen after application of Serotonin only Somatosensory representation in the Owl Monkey Sensibility training for several weeks [email protected] Somatosensory areas before (l) and after (r) training Similar effects were recently observed also in the human brain
