Journal of Computational Neuroscience

, Volume 32, Issue 2, pp 213–231

Random local temporal structure of category fluency responses

  • David J. Meyer
  • Jason Messer
  • Tanya Singh
  • Peter J. Thomas
  • Wojbor A. Woyczynski
  • Jeffrey Kaye
  • Alan J. Lerner
Article

DOI: 10.1007/s10827-011-0349-5

Cite this article as:
Meyer, D.J., Messer, J., Singh, T. et al. J Comput Neurosci (2012) 32: 213. doi:10.1007/s10827-011-0349-5

Abstract

The Category Fluency Test (CFT) provides a sensitive measurement of cognitive capabilities in humans related to retrieval from semantic memory. In particular, it is widely used to assess progress of cognitive impairment in patients with dementia. Previous research shows that, in the first approximation, the intensity of tested individuals’ responses within a standard 60-s test period decays exponentially with time, with faster decay rates for more cognitively impaired patients. Such decay rate can then be viewed as a global (macro) diagnostic parameter of each test. In the present paper we focus on the statistical properties of the properly de-trended time intervals between consecutive responses (inter-call times) in the Category Fluency Test. In a sense, those properties reflect the local (micro) structure of the response generation process. We find that a good approximation for the distribution of the de-trended inter-call times is provided by the Weibull Distribution, a probability distribution that appears naturally in this context as a distribution of a minimum of independent random quantities and is the standard tool in industrial reliability theory. This insight leads us to a new interpretation of the concept of “navigating a semantic space” via patient responses.

Keywords

Category Fluency Test Semantic memory Cognitive impairment Alzheimer’s disease Statistical temporal structure Weibull distribution Inter response times 

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • David J. Meyer
    • 1
  • Jason Messer
    • 1
  • Tanya Singh
    • 1
  • Peter J. Thomas
    • 2
    • 3
  • Wojbor A. Woyczynski
    • 4
  • Jeffrey Kaye
    • 5
    • 6
  • Alan J. Lerner
    • 7
  1. 1.Case Western Reserve UniversityClevelandUSA
  2. 2.Departments of Mathematics, Biology and Cognitive ScienceCase Western Reserve UniversityClevelandUSA
  3. 3.Department of NeuroscienceOberlin CollegeOberlinUSA
  4. 4.Department of Statistics and Center for Stochastic and Chaotic Processes in Science and TechnologyCase Western Reserve UniversityClevelandUSA
  5. 5.Departments of Neurology and Biomedical EngineeringOregon Health and Science UniversityPortlandUSA
  6. 6.Portland Veterans Affairs Medical CenterPortlandUSA
  7. 7.Department of Neurology, Case Medical CenterCase Western Reserve UniversityClevelandUSA

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