Fundamental bound on the persistence and capacity of short-term memory stored as graded persistent activity

Abstract
Article and author information

Abstract

It is widely believed that persistent neural activity underlies short-term memory. Yet, as we show, temporal degradation in such networks behaves differently from human short-term memory performance. We build a more general framework where the memory is viewed as a problem of passing information through noisy channels that represent analog persistent activity networks. Rather than directly storing information, such memory networks might hold information encoded to achieve robustness against noise. We derive a fundamental lower-bound on memory recall precision, which declines with storage duration and number of stored items. We show that human performance, though inconsistent with models involving direct (uncoded) storage in persistent activity networks, can be well-fit by the theoretical bound. This finding is consistent with the view that if the brain stores information in patterns of persistent activity, it might use codes that minimize the effects of noise, motivating the search for such codes in the brain.

Article and author information

Author details

Onur Ozan Koyluoglu

Department of Electrical and Computer Science, University of California, Berkeley, United States

For correspondence
ozan.koyluoglu@berkeley.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-8512-4755
Yoni Pertzov

Department of Psychology, Hebrew University of Jerusalem, Jerusalem, Israel

Competing interests
The authors declare that no competing interests exist.
Sanjay Manohar

Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-0735-4349
Masud Husain

Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Ila R Fiete

Center for Learning and Memory, The University of Texas at Austin, Austin, United States

Competing interests
The authors declare that no competing interests exist.

Funding

National Science Foundation (IIS-1464349)

Onur Ozan Koyluoglu

Israeli Science Foundation (1747/14)

Yoni Pertzov

National Institute for Health Research (Oxford Biomedical Centre)

Masud Husain

Wellcome Trust

Masud Husain

National Science Foundation (IIS-1148973)

Ila R Fiete

Simons Foundation

Ila R Fiete

Howard Hughes Medical Institute (Faculty Scholar Award)

Ila R Fiete

MRC Clinician Scientist Fellowship (MR/P00878X)

Sanjay Manohar

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: The study reported here conform to the Declaration of Helsinki and all procedures were approved by the ethics committee of the National Hospital for Neurology and Neurosurgery (NHNN) prior to the study commencing. Research Ethics Committee number (ERC) 04/Q0406/60. Personal information about individuals was password protected and saved in compliance to the Data Protection Act 1998 (DPA).

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.