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Updated: May 1, 2026

Topographical Estimation of Visual Population Receptive Fields by fMRI
Published on: February 3, 2015
Random fields, topology, and the Imry-Ma argument.
Thomas C Proctor1, Dmitry A Garanin1, Eugene M Chudnovsky1
1Physics Department, Lehman College, City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, USA.
The study reveals that the behavior of random field models depends on the number of components (n) and dimensions (d). Systems with n ≤ d exhibit strong metastability due to topological defects, while n > d+1 leads to a predictable lowest-energy state.
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Area of Science:
- Statistical Physics
- Condensed Matter Physics
- Complex Systems
Background:
- Understanding the behavior of systems with quenched disorder is crucial.
- Topological defects play a significant role in the dynamics of many physical systems.
- Metastability and glassy behavior are key phenomena in disordered systems.
Purpose of the Study:
- To investigate the influence of topological defects on the relaxation dynamics and correlation functions.
- To explore the dimensional and component-number dependence of system behavior in random fields.
- To characterize the final states and their dependence on initial conditions.
Main Methods:
- Simulations on large lattices (hundreds of millions of sites).
- Analysis of spin-spin correlation functions.
- Study of relaxation dynamics from an initially ordered state.
Main Results:
- For n ≤ d, topological defects cause strong metastability and initial-condition-dependent final states.
- For n = d+1, weak metastability is observed.
- For n > d+1, topological objects are absent, leading to a unique lowest-energy state with exponential correlation decay.
Conclusions:
- The number of components (n) relative to dimensions (d) dictates the presence and impact of topological defects.
- Systems with n ≤ d exhibit complex glassy behavior, while higher n values lead to simpler, predictable states.
- Results align quantitatively with the Imry-Ma argument for higher component numbers.

