Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (528 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
A functional relationship between psychological phenomena of such nature that the presence of one tends to evoke the other; also, the process by which such a relationship is established.
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Associations.
Where it fits in the MeSH classification
- Broader topics
- Learning; Psychotherapeutic Processes
- Narrower topics
- Association Learning
- See also
- Word Association Tests
Research landscape
PubMed indexes 15,045 records tagged with the MeSH heading “Association” (counts retrieved 2026-10-31). 943 of them (6.3%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 5,070 records.
Reviews account for 951 records (6.3%) and meta-analyses for 29. Randomized controlled trials number 436 (2.9%) as a share of all records on the topic.
Show the data
| Period | Records |
|---|---|
| through 1999 | 4,259 |
| 2000-2009 | 4,773 |
| 2010-2019 | 5,070 |
| 2020 onward | 943 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 951 | 6.3% |
| Meta-analyses | 29 | 0.2% |
| Randomized controlled trials | 436 | 2.9% |
Method: PubMed query "Association"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in psychiatry and psychology
Research on mental health and behaviour relies on questionnaires, interviews and rating scales rather than physical measurements, so how a condition was defined and measured shapes every result. Many studies are observational or small, placebo responses can be large, and findings in one group or culture may not carry over to another. Nothing on this page is advice about diagnosis or treatment; anyone worried about their mental health should talk to a qualified clinician. Check how outcomes were measured, who took part and how long they were followed.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Infralimbic cortex is required for learning alternatives to prelimbic promoted associations through reciprocal connectivity | 2018 | Research article Design not recorded in structured metadata | 76 | cc by PMID 30006525 · DOI · PMC6045592 |
| Hippocampal pattern separation supports reinforcement learning | 2019 | Research article Design not recorded in structured metadata | 52 | cc by PMID 30842581 · DOI · PMC6403348 |
| Nicotinic Acetylcholine Receptors Control Encoding and Retrieval of Associative Recognition Memory through Plasticity in the Medial Prefrontal Cortex | 2018 | Research article Design not recorded in structured metadata | 41 | cc by PMID 29590611 · DOI · PMC5896173 |
| Bold zebrafish (Danio rerio) learn faster in a classical associative learning task | 2025 | Research article Design not recorded in structured metadata | 12 | cc by PMID 40348810 · DOI · PMC12065844 |
Infralimbic cortex is required for learning alternatives to prelimbic promoted associations through reciprocal connectivity [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Prefrontal cortical areas mediate flexible adaptive control of behavior, but the specific contributions of individual areas and the circuit mechanisms through which they interact to modulate learning have remained poorly understood.
- Closing excerpt
- Our results define specific and opposing roles of PreL and IL to together flexibly support new learning, and provide circuit evidence that IL-mediated learning of alternative associations depends on direct reciprocal PreL↔IL connectivity.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (152 words)
Prefrontal cortical areas mediate flexible adaptive control of behavior, but the specific contributions of individual areas and the circuit mechanisms through which they interact to modulate learning have remained poorly understood. Using viral tracing and pharmacogenetic techniques, we show that prelimbic (PreL) and infralimbic cortex (IL) exhibit reciprocal PreL↔IL layer 5/6 connectivity. In set-shifting tasks and in fear/extinction learning, activity in PreL is required during new learning to apply previously learned associations, whereas activity in IL is required to learn associations alternative to previous ones. IL→PreL connectivity is specifically required during IL-dependent learning, whereas reciprocal PreL↔IL connectivity is required during a time window of 12-14 h after association learning, to set up the role of IL in subsequent learning. Our results define specific and opposing roles of PreL and IL to together flexibly support new learning, and provide circuit evidence that IL-mediated learning of alternative associations depends on direct reciprocal PreL↔IL connectivity.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 30006525 · DOI · PMC6045592
Hippocampal pattern separation supports reinforcement learning [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Animals rely on learned associations to make decisions.
- Closing excerpt
- Our results establish a novel role for hippocampal pattern separation and conjunctive representation in reinforcement learning.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (147 words)
Animals rely on learned associations to make decisions. Associations can be based on relationships between object features (e.g., the three leaflets of poison ivy leaves) and outcomes (e.g., rash). More often, outcomes are linked to multidimensional states (e.g., poison ivy is green in summer but red in spring). Feature-based reinforcement learning fails when the values of individual features depend on the other features present. One solution is to assign value to multi-featural conjunctive representations. Here, we test if the hippocampus forms separable conjunctive representations that enables the learning of response contingencies for stimuli of the form: AB+, B-, AC-, C+. Pattern analyses on functional MRI data show the hippocampus forms conjunctive representations that are dissociable from feature components and that these representations, along with those of cortex, influence striatal prediction errors. Our results establish a novel role for hippocampal pattern separation and conjunctive representation in reinforcement learning.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 30842581 · DOI · PMC6403348
Nicotinic Acetylcholine Receptors Control Encoding and Retrieval of Associative Recognition Memory through Plasticity in the Medial Prefrontal Cortex [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Nicotinic acetylcholine receptors (nAChRs) expressed in the medial prefrontal cortex have critical roles in cognitive function.
- Closing excerpt
- We present evidence that these separate roles of nAChRs may rely on bidirectional modulation of plasticity at synaptic inputs to the prefrontal cortex that are essential for associative recognition memory.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (86 words)
Nicotinic acetylcholine receptors (nAChRs) expressed in the medial prefrontal cortex have critical roles in cognitive function. However, whether nAChRs are required for associative recognition memory and the mechanisms by which nAChRs may contribute to mnemonic processing are not known. We demonstrate that nAChRs in the prefrontal cortex exhibit subtype-specific roles in associative memory encoding and retrieval. We present evidence that these separate roles of nAChRs may rely on bidirectional modulation of plasticity at synaptic inputs to the prefrontal cortex that are essential for associative recognition memory.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 29590611 · DOI · PMC5896173
Bold zebrafish (Danio rerio) learn faster in a classical associative learning task [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Animals vary between individuals in their ability to learn and some sources of this variation can be the learning process and the individual's personality type.
- Closing excerpt
- The lack of differences in the final change in behavior suggests that learning differences may be due to how the animals initially interact with stimuli because of differences in neophobia.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (143 words)
Animals vary between individuals in their ability to learn and some sources of this variation can be the learning process and the individual's personality type. We investigated the relationship between learning and the bold-shy behavioral type by comparing performance of bold and shy zebrafish in conditioned place preference (CPP) and 2-choice tasks. Bold zebrafish learned significantly faster than the shy fish but there were no differences in their final performance in the CPP. When tested in the 2-choice task, we found no clear evidence of learning, however bold fish made more initial choices than shy fish. Overall, our study suggests that bold zebrafish tend to be faster learners when compared to shy zebrafish. The lack of differences in the final change in behavior suggests that learning differences may be due to how the animals initially interact with stimuli because of differences in neophobia.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40348810 · DOI · PMC12065844
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Neural mechanisms of addiction: the role of reward-related learning and memory [5]
- Research article The role of medial prefrontal cortex in memory and decision making [6]
- Research article The brain's default network: updated anatomy, physiology and evolving insights [7]
- Research article Understanding and using the Implicit Association Test: III. Meta-analysis of predictive validity [8]
- Research article Frontal cortex and reward-guided learning and decision-making [9]
- Research article Crossmodal correspondences: a tutorial review [10]
Full-text reviews on EvidenceLib
Open-access review articles about this topic, reproduced in full with authors, licence and references.
Association between green space exposure and elderly health: a systematic review and meta-analysis
Mengyao Wang, Yajie Che, Xinyun Tan et al. · BMC Public Health 2026 · CC BY 4.0
Associations Between Multimorbidity, Polypharmacy and Oral Conditions in Older Adults: A Systematic Review and Meta‐Analysis
Kittipit Srisanoi, Sabrina Maniewicz, Claudio Rodrigues Leles et al. · Gerodontology 2026 · CC BY 4.0
The association between maternal prenatal folic acid and multivitamin supplementation and autism spectrum disorders in offspring: An umbrella review
Biruk Beletew Abate, Biruk Shalmeno Tusa, Ashenafi Kibret Sendekie et al. · PLOS One 2025 · CC BY 4.0
Hidradenitis suppurativa and its association with obesity, smoking, and diabetes mellitus: A systematic review and meta‐analysis
Khaled E. Elzawawi, Ibrahim Elmakaty, Mohammad Habibullah et al. · International Wound Journal 2024 · CC BY 4.0
The Association of a Vegan Diet during Pregnancy with Maternal and Child Outcomes: A Systematic Review
Deidre Meulenbroeks, Eline Otten, Sophie Smeets et al. · Nutrients 2024 · CC BY 4.0
References
- Mukherjee A, Caroni P. Infralimbic cortex is required for learning alternatives to prelimbic promoted associations through reciprocal connectivity. . 2018. PMID 30006525 · DOI · PMC6045592
- Ballard IC, Wagner AD, McClure SM. Hippocampal pattern separation supports reinforcement learning. . 2019. PMID 30842581 · DOI · PMC6403348
- Sabec MH, Wonnacott S, Warburton EC, Bashir ZI. Nicotinic Acetylcholine Receptors Control Encoding and Retrieval of Associative Recognition Memory through Plasticity in the Medial Prefrontal Cortex. . 2018. PMID 29590611 · DOI · PMC5896173
- Corcoran J, Storks L, Wong RY. Bold zebrafish (Danio rerio) learn faster in a classical associative learning task. . 2025. PMID 40348810 · DOI · PMC12065844
- Hyman SE, Malenka RC, Nestler EJ. Neural mechanisms of addiction: the role of reward-related learning and memory. Annu Rev Neurosci. 2006. PMID 16776597 · DOI
- Euston DR, Gruber AJ, McNaughton BL. The role of medial prefrontal cortex in memory and decision making. Neuron. 2012. PMID 23259943 · DOI · PMC3562704
- Buckner RL, DiNicola LM. The brain's default network: updated anatomy, physiology and evolving insights. Nat Rev Neurosci. 2019. PMID 31492945 · DOI
- Greenwald AG, Poehlman TA, Uhlmann EL, Banaji MR. Understanding and using the Implicit Association Test: III. Meta-analysis of predictive validity. J Pers Soc Psychol. 2009. PMID 19586237 · DOI
- Rushworth MF, Noonan MP, Boorman ED, Walton ME, Behrens TE. Frontal cortex and reward-guided learning and decision-making. Neuron. 2011. PMID 21689594 · DOI
- Spence C. Crossmodal correspondences: a tutorial review. Atten Percept Psychophys. 2011. PMID 21264748 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.