title: Neural Network Model of Memory Retrieval.
abstract: Human memory can store large amount of information. Nevertheless, recalling is often a challenging task. In a classical free recall paradigm, where participants are asked to repeat a briefly presented list of words, people make mistakes for lists as short as 5 words. We present a model for memory retrieval based on a Hopfield neural network where transition between items are determined by similarities in their long-term memory representations. Meanfield analysis of the model reveals stable states of the network corresponding (1) to single memory representations and (2) intersection between memory representations. We show that oscillating feedback inhibition in the presence of noise induces transitions between these states triggering the retrieval of different memories. The network dynamics qualitatively predicts the distribution of time intervals required to recall new memory items observed in experiments. It shows that items having larger number of neurons in their representation are statistically easier to recall and reveals possible bottlenecks in our ability of retrieving memories. Overall, we propose a neural network model of information retrieval broadly compatible with experimental observations and is consistent with our recent graphical model (Romani et al., 2013).
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel.
authors.forename: Stefano
authors.initials: S
authors.lastname: Recanatesi
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Katkov
authors.affiliation: Janelia Farm Research Campus, Howard Hughes Medical Institute Ashburn, VA, USA.
authors.forename: Sandro
authors.initials: S
authors.lastname: Romani
authors.affiliation: Department of Neurobiology, Weizmann Institute of ScienceRehovot, Israel; Department of Neurotechnologies, Lobachevsky State University of Nizhny NovgorodNizhny Novgorod, Russia.
authors.forename: Misha
authors.initials: M
authors.lastname: Tsodyks
keywords: attractor neural networks; memory; neural representations; oscillations; recall