Neural correlates of derived relational responding on tests of stimulus equivalence

Neural correlates of derived relational responding on tests of stimulus equivalence

Date: February 1, 2008
Creator: Schlund, Michael W.; Cataldo, Michael F. & Hoehn-Saric, Rudolf
Description: This article discusses neural correlates of derived relational responding on tests of stimulus equivalence. Background: An essential component of cognition and language involves the formation of new conditional relations between stimuli based upon prior experiences. Results of investigations on transitive inference (TI) highlight a prominent role for the medial temporal lobe in maintaining associative relations among sequentially arranged stimuli (A > B > C > D > E). In this investigation, medial temporal lobe activity was assessed while subjects completed "Stimulus Equivalence" (SE) tests that required deriving conditional relations among stimuli within a class (A ≡ B ≡ C). Methods: Stimuli consisted of six consonant-vowel-consonant triads divided into two classes (A1, B1, C1; A2, B2, C2). A simultaneous matching-to-sample task and differential reinforcement were employed during pretraining to establish the conditional relations A1:B1 and B1:C1 in class 1 and A2:B2 and B2:C2 in class 2. During functional neuroimaging, recombined stimulus pairs were presented and subjects judged (yes/no) whether stimuli were related. SE tests involved presenting three different types of within-class pairs: Symmetrical (B1 A1; C1 B1; B2 A2; C2 B2), and Transitive (A1 C1; A2 C2) and Equivalence (C1 A1; C2 A2) relations separated by a nodal stimulus. Cross-class 'Foils' ...
Contributing Partner: UNT College of Arts and Sciences
Generalized anxiety modulates frontal and limbic activation in major depression

Generalized anxiety modulates frontal and limbic activation in major depression

Date: February 9, 2012
Creator: Schlund, Michael W.; Verduzco, Guillermo; Cataldo, Michael F. & Hoehn-Saric, Rudolf
Description: This article discusses generalized anxiety modulates frontal and limbic activation in major depression. Abstract: Background: Anxiety is relatively common in depression and capable of modifying the severity and course of depression. Yet our understanding of how anxiety modulates frontal and limbic activation in depression is limited. Methods: The authors used functional magnetic resonance imaging and two emotional information processing tasks to examine frontal and limbic activation in ten patients with major depression and comorbid with preceding generalized anxiety (MDD/GAD) and ten non-depressed controls. Results: Consistent with prior studies on depression, MDD/GAD patients showed hypoactivation in medial and middle frontal regions, as well as in the anterior cingulate and insula. However, heightened anxiety in MDD/GAD patients was associated with increased activation in middle frontal regions and the insula and the effects varied with the type of emotional information presented. Conclusions: The authors' findings highlight frontal and limbic hypoactivation in patients with depression and comorbid anxiety and indicate that anxiety level may modulate frontal and limbic activation depending upon the emotional context. One implication of this finding is that divergent findings reported in the imaging literature on depression could reflect modulation of activation by anxiety level in response to different types of ...
Contributing Partner: UNT College of Public Affairs and Community Service
Generalized anxiety modulates frontal and limbic activation in major depression

Generalized anxiety modulates frontal and limbic activation in major depression

Date: February 9, 2012
Creator: Schlund, Michael W.; Verduzco, Guillermo; Cataldo, Michael F. & Hoehn-Saric, Rudolf
Description: This article discusses generalized anxiety modulates frontal and limbic activation in major depression. Abstract: Background: Anxiety is relatively common in depression and capable of modifying the severity and course of depression. Yet our understanding of how anxiety modulates frontal and limbic activation in depression is limited. Methods: The authors used functional magnetic resonance imaging and two emotional information processing tasks to examine frontal and limbic activation in ten patients with major depression and comorbid with preceding generalized anxiety (MDD/GAD) and ten non-depressed controls. Results: Consistent with prior studies on depression, MDD/GAD patients showed hypoactivation in medial and middle frontal regions, as well as in the anterior cingulate and insula. However, heightened anxiety in MDD/GAD patients was associated with increased activation in middle frontal regions and the insula and the effects varied with the type of emotional information presented. Conclusions: The authors' findings highlight frontal and limbic hypoactivation in patients with depression and comorbid anxiety and indicate that anxiety level may modulate frontal and limbic activation depending upon the emotional context. One implication of this finding is that divergent findings reported in the imaging literature on depression could reflect modulation of activation by anxiety level in response to different types of ...
Contributing Partner: UNT College of Arts and Sciences