Neuronal population coding of parametric working memory.
Comparing two sequentially presented stimuli is a widely used experimental paradigm for studying working memory. The delay activity of many single neurons in the prefrontal cortex (PFC) of monkeys was found to be stimulus-specific, however, population dynamics of stimulus representation has not been elucidated. We analyzed the population state of a large number of PFC neurons during a somatosensory discrimination task. Using the tuning curves of the neurons, we derived a compact characterization of the population state. Stimulus representation by the population was found to degrade after stimulus termination, and emerge in a different form toward the end of the delay. Specifically, the tuning properties of neurons were found to change during the task. We suggest a mechanism whereby information about the stimulus is contained in activity-dependent synaptic facilitation of recurrent connections.
Barak
Omri
O
Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Tsodyks
Misha
M
Romo
Ranulfo
R
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004193:Discrimination Learning / Q000502:physiology; D004594:Electrophysiology; D008253:Macaca mulatta; D008570:Memory, Short-Term / Q000502:physiology*; D008959:Models, Neurological; D009043:Motor Activity / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012044:Regression Analysis