לוח שנה משולב

Since the discovery of place cells in the hippocampus, a variety of experimental observations have pointed to the complexity of hippocampal circuit dynamics and their importance in memory related tasks. During spatial navigation, place cell activity predicts the upcoming animal location within the short time scale of individual cycles of theta oscillations. Sudden changes of the spatial context are followed by a bistability between population coding of past and current context, paced by the theta rhythm. During immobility, brief sequences of place cell activation encode spatial trajectories, which have been linked to learning in spatial memory tasks and goal-directed navigation. Finally, when the animal is engaged in a delayed memory task, hippocampal cells fire at specific time intervals within the delay period and the activity of a population of cells is predictive of the behavioral outcome. I will present a unified attractor network model that accounts for this wide range of experimental observations. A critical component of the model is the use of realistic synapses that exhibit short-term plasticity driven by presynaptic activity. Complexity in the network dynamics emerges due to the effect of history dependent synaptic states on the network activity. Model predictions, possible extensions of the model and its relationship to dynamics observed in other cortical areas will be discussed.