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ORIGINAL RESEARCH article

Front. Hum. Neurosci.

Sec. Cognitive Neuroscience

Volume 19 - 2025 | doi: 10.3389/fnhum.2025.1595331

Monotonicity in graph theoretic summaries of fMRI data acquired during human learning

Provisionally accepted
Clifford  AbelClifford Abel1John  KopchickJohn Kopchick1Dhruval  BhattDhruval Bhatt1Patricia  ThomasPatricia Thomas1Usha  RajanUsha Rajan1Dalal  KhatibDalal Khatib1Caroline  Zajac-BenitezCaroline Zajac-Benitez1Luay  HaddadLuay Haddad1Alireza  AmirsadriAlireza Amirsadri1Jeffrey  A StanleyJeffrey A Stanley1Vaibhav  A. DiwadkarVaibhav A. Diwadkar2*
  • 1School of Medicine, Wayne State University, Detroit, Michigan, United States
  • 2Psychiatry & Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, MI, United States

The final, formatted version of the article will be published soon.

Behavioral performance during associative learning typically improves monotonically; performance on each successive iteration of the task is no worse (and typically better) than on the previous one. It is unclear whether connectomic measures of brain function (from fMRI data acquired during learning) also increase monotonically. We used a well-established associative learning paradigm to test for the possible co-observance of monotonicity in behavior and connectomics. fMRI data were summarized using two distinct connectomic (i.e., graph theoretic) measures: a) Betweenness Centrality (of nodes) and b) Average Shortest Path Length (i.e. a measure of network efficiency) across the graph. To broaden our study's breath, in addition to healthy controls (n = 39), we extended the analyses to data collected in schizophrenia patients (n = 49). Past studies show that although patients show deficits in learning (lower learning capacity), behavior does typically display monotonicity. In the current study, we observed robust evidence for monotonic changes in behavior at the group level, and in most participants regardless of group. Evidence for monotonic changes in graph theoretic summaries of the co-acquired fMRI data was less widespread and was in general, more evident in group level summaries (regardless of group). This modest co-observance of monotonicity in behavior and fMRI-based connectomics re-emphasizes what has long been suspected: the relationship between overt measures of behavioral competence and the co-acquired imaging signals is complex. This may be because psychological events (whether in the healthy brain, or in clinical populations like schizophrenia) emerge not from local activity in circumscribed brain regions, but rather from widely distributed activity across the brain. While well-defined mathematical concepts like monotonicity can anchor attempts to co-observe properties of change in overt behavior, and underlying brain signals, we suggest that the search for such relationships will remain a challenge.

Keywords: monotonicity, graph theory, Learning, Behavior, fMRI

Received: 17 Mar 2025; Accepted: 04 Sep 2025.

Copyright: © 2025 Abel, Kopchick, Bhatt, Thomas, Rajan, Khatib, Zajac-Benitez, Haddad, Amirsadri, Stanley and Diwadkar. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Vaibhav A. Diwadkar, Psychiatry & Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, 48201, MI, United States

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