IU Indianapolis ScholarWorks :: Browsing by Author "Lundin, Nancy B."

Browsing by Author "Lundin, Nancy B."

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Cerebellar Activation Deficits in Schizophrenia During an Eyeblink Conditioning Task
(Oxford University Press, 2021-08-28) Lundin, Nancy B.; Kim, Dae-Jin; Tullar, Rachel L.; Moussa-Tooks, Alexandra B.; Kent, Jerillyn S.; Newman, Sharlene D.; Purcell, John R.; Bolbecker, Amanda R.; O’Donnell, Brian F.; Hetrick, William P.; Psychiatry, School of Medicine
The cognitive dysmetria theory of psychotic disorders posits that cerebellar circuit abnormalities give rise to difficulties coordinating motor and cognitive functions. However, brain activation during cerebellar-mediated tasks is understudied in schizophrenia. Accordingly, this study examined whether individuals with schizophrenia have diminished neural activation compared to controls in key regions of the delay eyeblink conditioning (dEBC) cerebellar circuit (eg, lobule VI) and cerebellar regions associated with cognition (eg, Crus I). Participants with schizophrenia-spectrum disorders (n = 31) and healthy controls (n = 43) underwent dEBC during functional magnetic resonance imaging (fMRI). Images were normalized using the Spatially Unbiased Infratentorial Template (SUIT) of the cerebellum and brainstem. Activation contrasts of interest were "early" and "late" stages of paired tone and air puff trials minus unpaired trials. Preliminary whole brain analyses were conducted, followed by cerebellar-specific SUIT and region of interest (ROI) analyses of lobule VI and Crus I. Correlation analyses were conducted between cerebellar activation, neuropsychological test scores, and psychotic symptom scores. In controls, the largest clusters of cerebellar activation peaked in lobule VI during early dEBC and Crus I during late dEBC. The schizophrenia group showed robust cortical activation to unpaired trials but no significant conditioning-related cerebellar activation. Crus I ROI activation during late dEBC was greater in the control than schizophrenia group. Greater Crus I activation correlated with higher working memory scores in the full sample and lower positive psychotic symptom severity in schizophrenia. Findings indicate functional cerebellar abnormalities in schizophrenia which relate to psychotic symptoms, lending direct support to the cognitive dysmetria framework.
A cognitive model of diminished expression in schizophrenia: The interface of metacognition, cognitive symptoms and language disturbances
(Elsevier, 2020-12) García-Mieres, Helena; Lundin, Nancy B.; Minor, Kyle S.; Dimaggio, Giancarlo; Popolo, Raffaele; Cheli, Simone; Lysaker, Paul H.; Psychology, School of Science
The resistance of negative symptoms to pharmacologic treatment has spurred interest in understanding the psychological factors that contribute to their formation and persistence. However, little is understood about the psychological processes that reinforce and sustain the negative symptoms domain of diminished expression. Prior research has shown that higher levels of diminished expression relate to deficits in metacognitive capacity. We propose a more complex model in which diminished expression occurs when impairments in metacognitive self-reflectivity, alterations in higher-order language structure, and cognitive symptoms interact and thus interfere with persons' ability to understand and express emotions in ways others can recognize. Individuals with schizophrenia-spectrum disorders (N = 201) provided personal narratives detailing their life story and reflections about their mental illness. Self-reflectivity was measured with the Metacognition Assessment Scale-Abbreviated, and situation models were extracted from participants' personal narratives via Coh-Metrix 3.0, an automated program that calculates language indices. Diminished expression and cognitive symptoms were measured with the Positive and Negative Syndrome Scale. Structural equation models (SEM) examined whether self-reflectivity mediated the impact of cognitive symptoms and situation models on diminished expression. Results of the SEM revealed that self-reflectivity partially mediated the impact of situation models on diminished expression (β = -.073, p = .008, ±95% CI [-0.126, -0.019]). and fully mediated the influence of cognitive symptoms in diminished expression (β = 0.099, p = .001, ±95% CI [0.038, 0.160]). In conclusion, results suggest that self-reflectivity, linguistic cohesion, and cognitive symptoms may be useful targets for intervention in efforts to treat diminished expression in psychosis.
The Independent Relationships of Metacognition, Mindfulness, and Cognitive Insight to Self-Compassion in Schizophrenia
(Wolters Kluwer, 2020-01) Hochheiser, Jesse; Lundin, Nancy B.; Lysaker, Paul H.; Psychiatry, School of Medicine
The debilitating nature of psychosis may be exacerbated by societal stigma and feelings of social isolation over and above positive (e.g., hallucinations) and negative (e.g., flat affect) symptoms. Thus, recovery may be facilitated by increasing self-compassion, the ability to respond with a nonjudgmental attitude of kindness toward oneself as a result of connecting with one's own inadequacies and suffering. We conducted a stepwise regression in individuals with schizophrenia-spectrum disorders (n = 92) to determine the unique contributions of cognitive variables in predicting self-compassion, such as metacognition (the ability to form complex and integrated ideas about oneself and others), mindfulness, and cognitive insight. Results indicated that increased metacognitive awareness of others and mindfulness uniquely predicted greater self-compassion (i.e., self-kindness), whereas increased cognitive insight predicted greater lack of self-compassion (i.e., self-judgment). These findings suggest the potential for mindfulness and metacognitive interventions to increase positive self-compassion and promote recovery in psychosis.
Neural evidence of switch processes during semantic and phonetic foraging in human memory
(National Academy of Science, 2023) Lundin, Nancy B.; Brown, Joshua W.; Johns, Brendan T.; Jones, Michael N.; Purcell, John R.; Hetrick, William P.; O’Donnell, Brian F.; Todd, Peter M.; Psychiatry, School of Medicine
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.
Piecing together fragments: Linguistic cohesion mediates the relationship between executive function and metacognition in schizophrenia
(Elsevier, 2020-01) Lundin, Nancy B.; Hochheiser, Jesse; Minor, Kyle S.; Hetrick, William P.; Lysaker, Paul H.; Psychiatry, School of Medicine
Speech disturbances are prevalent in psychosis. These may arise in part from executive function impairment, as research suggests that inhibition and monitoring are associated with production of cohesive discourse. However, it is not yet understood how linguistic and executive function impairments in psychosis interact with disrupted metacognition, or deficits in the ability to integrate information to form a complex sense of oneself and others and use that synthesis to respond to psychosocial challenges. Whereas discourse studies have historically employed manual hand-coding techniques, automated computational tools can characterize deep semantic structures that may be closely linked with metacognition. In the present study, we examined whether higher executive functioning promotes metacognition by way of altering linguistic cohesion. Ninety-four individuals with schizophrenia-spectrum disorders provided illness narratives and completed an executive function task battery (Delis-Kaplan Executive Function System). We assessed the narratives for linguistic cohesion (Coh-Metrix 3.0) and metacognitive capacity (Metacognition Assessment Scale – Abbreviated). Selected linguistic indices measured the frequency of connections between causal and intentional content (deep cohesion), word and theme overlap (referential cohesion), and unique word usage (lexical diversity). In path analyses using bootstrapped confidence intervals, we found that deep cohesion and lexical diversity independently mediated the relationship between executive functioning and metacognitive capacity. Findings suggest that executive control abilities support integration of mental experiences by way of increasing causal, goal-driven speech and word expression in individuals with schizophrenia. Metacognitive-based therapeutic interventions for psychosis may promote insight and recovery in part by scaffolding use of language that links ideas together.
Polarity- and Intensity-Independent Modulation of Timing During Delay Eyeblink Conditioning Using Cerebellar Transcranial Direct Current Stimulation
(SpringerLink, 2020-06) Mitroi, Jessica; Burroughs, Leah; Moussa-Tooks, Alexandra B.; Bolbecker, Amanda R.; Lundin, Nancy B.; O’Donnell, Brian F.; Hetrick, William P.; Psychiatry, School of Medicine
Delay eyeblink conditioning (dEBC) is widely used to assess cerebellar-dependent associative motor learning, including precise timing processes. Transcranial direct current stimulation (tDCS), noninvasive brain stimulation used to indirectly excite and inhibit select brain regions, may be a promising tool for understanding how functional integrity of the cerebellum influences dEBC behavior. The aim of this study was to assess whether tDCS-induced inhibition (cathodal) and excitation (anodal) of the cerebellum differentially impact timing of dEBC. A standard 10-block dEBC paradigm was administered to 102 healthy participants. Participants were randomized to stimulation conditions in a double-blind, between-subjects sham-controlled design. Participants received 20-min active (anodal or cathodal) stimulation at 1.5 mA (n = 20 anodal, n = 22 cathodal) or 2 mA (n = 19 anodal, n = 21 cathodal) or sham stimulation (n = 20) concurrently with dEBC training. Stimulation intensity and polarity effects on percent conditioned responses (CRs) and CR peak and onset latency were examined using repeated-measures analyses of variance. Acquisition of CRs increased over time at a similar rate across sham and all active stimulation groups. CR peak and onset latencies were later, i.e., closer to air puff onset, in all active stimulation groups compared to the sham group. Thus, tDCS facilitated cerebellar-dependent timing of dEBC, irrespective of stimulation intensity and polarity. These findings highlight the feasibility of using tDCS to modify cerebellar-dependent functions and provide further support for cerebellar contributions to human eyeblink conditioning and for exploring therapeutic tDCS interventions for cerebellar dysfunction.
Schizophrenia, recovery and the self: An introduction to the special issue on metacognition
(Elsevier, 2020-03) Lysaker, Paul H.; Keane, Jennifer E.; Culleton, Sara Poirier; Lundin, Nancy B.; Psychology, School of Science
In this special issue, work is presented linking metacognition among persons with schizophrenia with a range of psychosocial outcomes including vocational functioning, empathy, motivation, self-evaluation, and other cognitive functions. This overview will highlight how these works allow for the quantitative study of processes which underpin alterations in self-experience in schizophrenia, which in turn allows self-experience to be studied as part of a larger set of brain-based and social phenomena whose interaction influences the trajectory of one's life and illness. We explore the hypothesis that metacognitive capacity, as a node in a larger biopsychosocial network, may be accessible by psychosocial treatment and, if successfully targeted, may disrupt the processes which perpetuate disability. Limitations and directions for future research are also discussed.
Semantic and phonetic similarity of verbal fluency responses in early-stage psychosis
(Elsevier, 2022) Lundin, Nancy B.; Jones, Michael N.; Myers, Evan J.; Breier, Alan; Minor, Kyle S.; Psychology, School of Science
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.
Semantic Search in Psychosis: Modeling Local Exploitation and Global Exploration
(Oxford, 2020-04-20) Lundin, Nancy B.; Todd, Peter M.; Peter M., Michael N.; Avery, Johnathan E.; O’Donnell, Brian F.; Hetrick, William P.; Psychiatry, School of Medicine
Impairments in category verbal fluency task (VFT) performance have been widely documented in psychosis. These deficits may be due to disturbed “cognitive foraging” in semantic space, in terms of altered salience of cues that influence individuals to search locally within a subcategory of semantically related responses (“clustering”) or globally between subcategories (“switching”). To test this, we conducted a study in which individuals with schizophrenia (n = 21), schizotypal personality traits (n = 25), and healthy controls (n = 40) performed VFT with “animals” as the category. Distributional semantic model Word2Vec computed cosine-based similarities between words according to their statistical usage in a large text corpus. We then applied a validated foraging-based search model to these similarity values to obtain salience indices of frequency-based global search cues and similarity-based local cues. Analyses examined whether diagnosis predicted VFT performance, search strategies, cue salience, and the time taken to switch between vs search within clusters. Compared to control and schizotypal groups, individuals with schizophrenia produced fewer words, switched less, and exhibited higher global cue salience, indicating a selection of more common words when switching to new clusters. Global cue salience negatively associated with vocabulary ability in controls and processing speed in schizophrenia. Lastly, individuals with schizophrenia took a similar amount of time to switch to new clusters compared to control and schizotypal groups but took longer to transition between words within clusters. Findings of altered local exploitation and global exploration through semantic memory provide preliminary evidence of aberrant cognitive foraging in schizophrenia.

Browsing by Author "Lundin, Nancy B."

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