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Marko M, Michalko D, Kubinec A, Riečanský I. Measuring semantic memory using associative and dissociative retrieval tasks. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231208. [PMID: 38328566 PMCID: PMC10846956 DOI: 10.1098/rsos.231208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 01/11/2024] [Indexed: 02/09/2024]
Abstract
Recent theoretical advances highlighted the need for novel means of assessing semantic cognition. Here, we introduce the associative-dissociative retrieval task (ADT), positing a novel way to test inhibitory control over semantic memory retrieval by contrasting the efficacy of associative (automatic) and dissociative (controlled) retrieval on a standard set of verbal stimuli. All ADT measures achieved excellent reliability, homogeneity, and short-term temporal stability. Moreover, in-depth stimulus level analyses showed that the associative retrieval is easier for words evoking few but strong associates, yet such propensity hampers the inhibition. Finally, we provided critical support for the construct validity of the ADT measures, demonstrating reliable correlations with domain-specific measures of semantic memory functioning (semantic fluency and associative combination) but negligible correlations with domain-general capacities (processing speed and working memory). Together, we show that ADT provides simple yet potent and psychometrically sound measures of semantic memory retrieval and offers noteworthy advantages over the currently available assessment methods.
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Affiliation(s)
- Martin Marko
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Sienkiewiczova 1, Bratislava, 813 71, Slovakia
- Department of Applied Informatics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina F1, Bratislava, 842 48, Slovakia
| | - Drahomír Michalko
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Sienkiewiczova 1, Bratislava, 813 71, Slovakia
| | - Adam Kubinec
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Sienkiewiczova 1, Bratislava, 813 71, Slovakia
| | - Igor Riečanský
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Sienkiewiczova 1, Bratislava, 813 71, Slovakia
- Department of Psychiatry, Faculty of Medicine, Slovak Medical University in Bratislava, Limbova 12, Bratislava, 833 03, Slovakia
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Nour MM, McNamee DC, Liu Y, Dolan RJ. Trajectories through semantic spaces in schizophrenia and the relationship to ripple bursts. Proc Natl Acad Sci U S A 2023; 120:e2305290120. [PMID: 37816054 PMCID: PMC10589662 DOI: 10.1073/pnas.2305290120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/31/2023] [Indexed: 10/12/2023] Open
Abstract
Human cognition is underpinned by structured internal representations that encode relationships between entities in the world (cognitive maps). Clinical features of schizophrenia-from thought disorder to delusions-are proposed to reflect disorganization in such conceptual representations. Schizophrenia is also linked to abnormalities in neural processes that support cognitive map representations, including hippocampal replay and high-frequency ripple oscillations. Here, we report a computational assay of semantically guided conceptual sampling and exploit this to test a hypothesis that people with schizophrenia (PScz) exhibit abnormalities in semantically guided cognition that relate to hippocampal replay and ripples. Fifty-two participants [26 PScz (13 unmedicated) and 26 age-, gender-, and intelligence quotient (IQ)-matched nonclinical controls] completed a category- and letter-verbal fluency task, followed by a magnetoencephalography (MEG) scan involving a separate sequence-learning task. We used a pretrained word embedding model of semantic similarity, coupled to a computational model of word selection, to quantify the degree to which each participant's verbal behavior was guided by semantic similarity. Using MEG, we indexed neural replay and ripple power in a post-task rest session. Across all participants, word selection was strongly influenced by semantic similarity. The strength of this influence showed sensitivity to task demands (category > letter fluency) and predicted performance. In line with our hypothesis, the influence of semantic similarity on behavior was reduced in schizophrenia relative to controls, predicted negative psychotic symptoms, and correlated with an MEG signature of hippocampal ripple power (but not replay). The findings bridge a gap between phenomenological and neurocomputational accounts of schizophrenia.
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Affiliation(s)
- Matthew M. Nour
- Department of Psychiatry, University of Oxford, OxfordOX3 7JX, United Kingdom
- Max Planck University College London Centre for Computational Psychiatry and Ageing Research, LondonWC1B 5EH, United Kingdom
| | - Daniel C. McNamee
- Champalimaud Research, Centre for the Unknown, 1400-038Lisbon, Portugal
| | - Yunzhe Liu
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing100875, China
- Chinese Institute for Brain Research, Beijing102206, China
| | - Raymond J. Dolan
- Max Planck University College London Centre for Computational Psychiatry and Ageing Research, LondonWC1B 5EH, United Kingdom
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing100875, China
- Wellcome Centre for Human Neuroimaging, University College London, LondonWC1N 3AR, United Kingdom
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Lundin NB, Brown JW, Johns BT, Jones MN, Purcell JR, Hetrick WP, O’Donnell BF, Todd PM. Neural evidence of switch processes during semantic and phonetic foraging in human memory. Proc Natl Acad Sci U S A 2023; 120:e2312462120. [PMID: 37824523 PMCID: PMC10589708 DOI: 10.1073/pnas.2312462120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 09/06/2023] [Indexed: 10/14/2023] Open
Abstract
Humans may retrieve words from memory by exploring and exploiting in "semantic space" similar to how nonhuman animals forage for resources in physical space. This has been studied using the verbal fluency test (VFT), in which participants generate words belonging to a semantic or phonetic category in a limited time. People produce bursts of related items during VFT, referred to as "clustering" and "switching." The strategic foraging model posits that cognitive search behavior is guided by a monitoring process which detects relevant declines in performance and then triggers the searcher to seek a new patch or cluster in memory after the current patch has been depleted. An alternative body of research proposes that this behavior can be explained by an undirected rather than strategic search process, such as random walks with or without random jumps to new parts of semantic space. This study contributes to this theoretical debate by testing for neural evidence of strategically timed switches during memory search. Thirty participants performed category and letter VFT during functional MRI. Responses were classified as cluster or switch events based on computational metrics of similarity and participant evaluations. Results showed greater hippocampal and posterior cerebellar activation during switching than clustering, even while controlling for interresponse times and linguistic distance. Furthermore, these regions exhibited ramping activity which increased during within-patch search leading up to switches. Findings support the strategic foraging model, clarifying how neural switch processes may guide memory search in a manner akin to foraging in patchy spatial environments.
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Affiliation(s)
- Nancy B. Lundin
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Program in Neuroscience, Indiana University, Bloomington, IN47405
- Department of Psychiatry and Behavioral Health, The Ohio State University, Columbus, OH43210
| | - Joshua W. Brown
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Program in Neuroscience, Indiana University, Bloomington, IN47405
- Cognitive Science Program, Indiana University, Bloomington, IN47405
| | - Brendan T. Johns
- Department of Psychology, McGill University, Montréal, QCH3A 1G1, Canada
| | - Michael N. Jones
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Cognitive Science Program, Indiana University, Bloomington, IN47405
| | - John R. Purcell
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Program in Neuroscience, Indiana University, Bloomington, IN47405
- Department of Psychiatry, Brain Health Institute, Rutgers University, Piscataway, NJ08854
| | - William P. Hetrick
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Program in Neuroscience, Indiana University, Bloomington, IN47405
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN46202
| | - Brian F. O’Donnell
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Program in Neuroscience, Indiana University, Bloomington, IN47405
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN46202
| | - Peter M. Todd
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN47405
- Cognitive Science Program, Indiana University, Bloomington, IN47405
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Speers LJ, Bilkey DK. Maladaptive explore/exploit trade-offs in schizophrenia. Trends Neurosci 2023; 46:341-354. [PMID: 36878821 DOI: 10.1016/j.tins.2023.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/30/2023] [Accepted: 02/08/2023] [Indexed: 03/07/2023]
Abstract
Schizophrenia is a complex disorder that remains poorly understood, particularly at the systems level. In this opinion article we argue that the explore/exploit trade-off concept provides a holistic and ecologically valid framework to resolve some of the apparent paradoxes that have emerged within schizophrenia research. We review recent evidence suggesting that fundamental explore/exploit behaviors may be maladaptive in schizophrenia during physical, visual, and cognitive foraging. We also describe how theories from the broader optimal foraging literature, such as the marginal value theorem (MVT), could provide valuable insight into how aberrant processing of reward, context, and cost/effort evaluations interact to produce maladaptive responses.
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Affiliation(s)
- Lucinda J Speers
- Department of Psychology, University of Otago, Dunedin 9016, New Zealand
| | - David K Bilkey
- Department of Psychology, University of Otago, Dunedin 9016, New Zealand.
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Almeida VN, Radanovic M. Semantic processing and neurobiology in Alzheimer's disease and Mild Cognitive Impairment. Neuropsychologia 2022; 174:108337. [DOI: 10.1016/j.neuropsychologia.2022.108337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/17/2022] [Accepted: 07/17/2022] [Indexed: 11/28/2022]
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Progressive changes in descriptive discourse in First Episode Schizophrenia: a longitudinal computational semantics study. NPJ SCHIZOPHRENIA 2022; 8:36. [PMID: 35853894 PMCID: PMC9261094 DOI: 10.1038/s41537-022-00246-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 03/14/2022] [Indexed: 12/14/2022]
Abstract
AbstractComputational semantics, a branch of computational linguistics, involves automated meaning analysis that relies on how words occur together in natural language. This offers a promising tool to study schizophrenia. At present, we do not know if these word-level choices in speech are sensitive to the illness stage (i.e., acute untreated vs. stable established state), track cognitive deficits in major domains (e.g., cognitive control, processing speed) or relate to established dimensions of formal thought disorder. In this study, we collected samples of descriptive discourse in patients experiencing an untreated first episode of schizophrenia and healthy control subjects (246 samples of 1-minute speech; n = 82, FES = 46, HC = 36) and used a co-occurrence based vector embedding of words to quantify semantic similarity in speech. We obtained six-month follow-up data in a subsample (99 speech samples, n = 33, FES = 20, HC = 13). At baseline, semantic similarity was evidently higher in patients compared to healthy individuals, especially when social functioning was impaired; but this was not related to the severity of clinically ascertained thought disorder in patients. Across the study sample, higher semantic similarity at baseline was related to poorer Stroop performance and processing speed. Over time, while semantic similarity was stable in healthy subjects, it increased in patients, especially when they had an increasing burden of negative symptoms. Disruptions in word-level choices made by patients with schizophrenia during short 1-min descriptions are sensitive to interindividual differences in cognitive and social functioning at first presentation and persist over the early course of the illness.
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Lundin NB, Jones MN, Myers EJ, Breier A, Minor KS. Semantic and phonetic similarity of verbal fluency responses in early-stage psychosis. Psychiatry Res 2022; 309:114404. [PMID: 35066310 PMCID: PMC8863651 DOI: 10.1016/j.psychres.2022.114404] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 01/12/2022] [Accepted: 01/15/2022] [Indexed: 11/16/2022]
Abstract
Linguistic abnormalities can emerge early in the course of psychotic illness. Computational tools that quantify similarity of responses in standardized language-based tasks such as the verbal fluency test could efficiently characterize the nature and functional correlates of these disturbances. Participants with early-stage psychosis (n=20) and demographically matched controls without a psychiatric diagnosis (n=20) performed category and letter verbal fluency. Semantic similarity was measured via predicted context co-occurrence in a large text corpus using Word2Vec. Phonetic similarity was measured via edit distance using the VFClust tool. Responses were designated as clusters (related items) or switches (transitions to less related items) using similarity-based thresholds. Results revealed that participants with early-stage psychosis compared to controls had lower fluency scores, lower cluster-related semantic similarity, and fewer switches; mean cluster size and phonetic similarity did not differ by group. Lower fluency semantic similarity was correlated with greater speech disorganization (Communication Disturbances Index), although more strongly in controls, and correlated with poorer social functioning (Global Functioning: Social), primarily in the psychosis group. Findings suggest that search for semantically related words may be impaired soon after psychosis onset. Future work is warranted to investigate the impact of language disturbances on social functioning over the course of psychotic illness.
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Affiliation(s)
- Nancy B. Lundin
- Department of Psychological and Brain Sciences and Program in Neuroscience, Indiana University, Bloomington, IN, USA; Department of Psychiatry and Behavioral Health, The Ohio State University, Columbus, OH, USA
| | - Michael N. Jones
- Department of Psychological and Brain Sciences and Cognitive Science Program, Indiana University, Bloomington, IN, USA
| | - Evan J. Myers
- Department of Psychology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
| | - Alan Breier
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA; Eskenazi Midtown Prevention and Recovery Center for Early Psychosis, Indianapolis, IN, USA.
| | - Kyle S. Minor
- Department of Psychology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA; Eskenazi Midtown Prevention and Recovery Center for Early Psychosis, Indianapolis, IN, USA
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Palaniyappan L. Dissecting the neurobiology of linguistic disorganisation and impoverishment in schizophrenia. Semin Cell Dev Biol 2021; 129:47-60. [PMID: 34507903 DOI: 10.1016/j.semcdb.2021.08.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 08/13/2021] [Accepted: 05/06/2021] [Indexed: 12/16/2022]
Abstract
Schizophrenia provides a quintessential disease model of how disturbances in the molecular mechanisms of neurodevelopment lead to disruptions in the emergence of cognition. The central and often persistent feature of this illness is the disorganisation and impoverishment of language and related expressive behaviours. Though clinically more prominent, the periodic perceptual distortions characterised as psychosis are non-specific and often episodic. While several insights into psychosis have been gained based on study of the dopaminergic system, the mechanistic basis of linguistic disorganisation and impoverishment is still elusive. Key findings from cellular to systems-level studies highlight the role of ubiquitous, inhibitory processes in language production. Dysregulation of these processes at critical time periods, in key brain areas, provides a surprisingly parsimonious account of linguistic disorganisation and impoverishment in schizophrenia. This review links the notion of excitatory/inhibitory (E/I) imbalance at cortical microcircuits to the expression of language behaviour characteristic of schizophrenia, through the building blocks of neurochemistry, neurophysiology, and neurocognition.
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Affiliation(s)
- Lena Palaniyappan
- Department of Psychiatry,University of Western Ontario, London, Ontario, Canada; Robarts Research Institute,University of Western Ontario, London, Ontario, Canada; Lawson Health Research Institute, London, Ontario, Canada.
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Guerreiro L, Silva FN, Amancio DR. A comparative analysis of knowledge acquisition performance in complex networks. Inf Sci (N Y) 2021. [DOI: 10.1016/j.ins.2020.12.060] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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