A mechanism for the Hebb and the anti-Hebb processes underlying learning and memory.
In a previous paper, a model was presented showing how the group of Ca2+/calmodulin-dependent protein kinase II molecules contained within a postsynaptic density could stably store a graded synaptic weight. This paper completes the model by showing how bidirectional control of synaptic weight could be achieved. It is proposed that the quantitative level of the activity-dependent rise in postsynaptic Ca2+ determines whether the synaptic weight will increase or decrease. It is further proposed that reduction of synaptic weight is governed by protein phosphatase 1, an enzyme indirectly controlled by Ca2+ through reactions involving phosphatase inhibitor 1, cAMP-dependent protein kinase, calcineurin, and adenylate cyclase. Modeling of this biochemical system shows that it can function as an analog computer that can store a synaptic weight and modify it in accord with the Hebb and anti-Hebb learning rules.
Lisman
J
J
Department of Biology, Brandeis University, Waltham, MA 02254.
D000262:Adenylyl Cyclases / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D019703:Calcineurin; D002118:Calcium / Q000502:physiology; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D007700:Kinetics; D007858:Learning; D008568:Memory; D008959:Models, Neurological; D008960:Models, Psychological; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D054645:Protein Phosphatase 1; D013569:Synapses / Q000378:metabolism / Q000502:physiology*
D002148:Calmodulin-Binding Proteins; D000242:Cyclic AMP; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D000262:Adenylyl Cyclases; D002118:Calcium