The role of short-term depression in sustained neural activity in the prefrontal cortex: a simulation study

  • Authors:
  • Yasunobu Igarashi;Yuichi Sakumura;Shin Ishii

  • Affiliations:
  • Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan;Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan;Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan

  • Venue:
  • Neural Networks - 2006 Special issue: Neurobiology of decision making
  • Year:
  • 2006

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Abstract

Recent experimental researches have suggested that sustained neural activity in the prefrontal cortex is a process of memory retention in decision making. Previous theoretical studies indicate that a balance between recurrent excitation and feedback inhibition is important for sustaining the activity. To investigate a plausible balancing mechanism, we simulated a biophysically realistic network model. Our model shows that short-term depression (STD) enables the network to sustain its activity despite the presence of long-term inhibition by GABAB receptors and that the sustained firing rates have a bell-shaped dependence on the degree of STD. By analyzing the neural network dynamics, we show that the bell-shaped dependence on STD is formed by destabilizing the balance with either excessive or insufficient STD. We also show that the optimal degree of STD has a linear relationship with the neural network size. These results suggest that STD provides a balancing mechanism and controls levels of sustained activities of various size networks.