Topographic analysis of the development of individual activation patterns during performance monitoring in medial frontal cortex

Age-related improvements in human performance monitoring have been linked to maturation of medial frontal cortex (MFC) in healthy youth, however, imaging studies conflict regarding age-related changes in MFC activation patterns. Topographical analysis of single-subject activation enables measurement of variation in location of MFC activation by age, as well as other potentially influential factors (e.g., performance on task). In this study, 22 youth (ages 8–17 years) and 21 adults (ages 23–51 years) underwent functional magnetic resonance imaging during a performance monitoring task examining interference and errors. Single-subject factors (extent of MFC activation, age and accuracy) were entered into a three-level hierarchical linear model to test the influence of these characteristics on location of MFC activation. Activation shifted from a rostral/anterior to a more dorsal/posterior location with increasing age and accuracy during interference. Inclusion of age and accuracy accounted for almost all of the unexplained variance in location of interference-related activation within MFC. This pattern links improvement of performance-monitoring capacity to age-related increases in posterior MFC and decreases in anterior MFC activation. Taken together, these results show the maturation of performance monitoring capacity to depend on more focal engagement of posterior MFC substrate for cognitive control.     

Using video modeling on an iPad to teach generalized matching on a sorting mail task to adolescents with autism

Two multiple probe designs across three and four participants evaluated the effects of video modeling to teach a matching response (sorting mail) to seven adolescents with autism. Participants were instructed on one set of responses (five mail pieces) using video modeling, while concurrently monitoring two other sets for generalization effects. Results indicated that three participants learned their target set and generalized to the untrained sets, and two participants required an error correction procedure to achieve or approach mastery on their target set. Two participants did not acquire target sets with video based instruction. Data on setting generalization and maintenance are also provided for the participants who reached mastery. Participant variables that may relate to responding, limitations to the study, and directions for future research on video based instruction are discussed.     

Deconstructing the Dissociative Disorders

Abstract

Background: The religion Kardecism Spiritism accepts and fosters dissociative experiences such as spiritual incorporation, automatic writing and out-of-body experiences as part of its basic tenets. Mastery of these skills is valued and highly respected. Members undergo extensive formalized training under the guidance of experienced leaders who model socially appropriate religious behaviors.

Method: One hundred and ten subjects at a prominent Kardecist Center in São Paulo, Brazil, were assessed with a variety of questionnaires and scales which addressed socialization, happiness, religiosity, mediumship (for the measurement of religious-related dissociative behavior and its formal training), temperament (the Tridimensional Personality Questionnaire; TPQ), and general dissociative experiences (the Dissociative Experiences Scale; DES).

Results: Mediumship activity was associated with increased DES score in spite of good scores on socialization and adaptation. There was evidence for a positive association between mediumship training and the control of the religious-related dissociative experiences. Increased pathological dissociation was associated with younger age, less control of mediumship activity, poorer social support and more antecedent psychiatric symptomatology.

Conclusions: These findings partially support the sociocognitive theory for religious-related non-pathological dissociation. The results of pathological dissociators suggest a co-existing but distinct sub-population whose pathological dissociative experiences were not caused by social modeling.     

Deflections in Mandibular Major Connectors: A FEM Study

The major connector is the most vital component critically subjected to maximal stress concentration due to various forces acting on it. The main requirement of a major connector is its resistance to deformation by occlusal stresses. This resistance to deformation is a direct consequence of the rigidity of the major connector. Thus rigidity of the major connector is paramount to resist flexing and torquing forces that could be transmitted to the abutment teeth and other structures as destructive forces. The commonly used major connectors for the mandibular arch are lingual bar and lingual plate. In the present study, the deflection of various major connector designs due to occlusal load is assessed by finite element method. They have been analyzed through finite element models. The differences in the deflection behaviour of mandibular major connector used in Kennedy’s Class I, Class II, Class III, and Class IV edentulous situations have been compared. A CT scan of human edentulous mandible was taken and each section from symphysis to condylar region was projected on a graph paper and three-dimensional volumes were created from connected successive profiles to define the final solid geometry of cortical bone. Six framework models with different mandibular major connectors, lingual bar and lingual plate for Kennedy’s Class I, Class II, Class III, and Class IV situations were created. The three dimensional finite element models corresponding to the geometric model were generated using Ansys’s pre-processor. The model was assigned material properties. A vertical biting force of 20 N was applied. The results showed that the maximum deflection was seen in the saddle area when compared to other areas, i.e., major connector and the occlusal rest regions. The lingual bar in Kennedy’s Class III situation and lingual plate in Kennedy’s Class IV situation showed the least deflection when compared to Class I and Class II (distal extensions) situations. Lingual plate is more rigid major connector than lingual bar.     

Finite Element Model of Ocular Adduction by Active Extraocular Muscle Contraction

PurposeIn order to clarify the role of the optic nerve (ON) as a load on ocular rotation, we developed a finite element model (FEM) of incremental adduction induced by active contractility of extraocular muscles (EOMs), with and without tethering by the ON.MethodsThree-dimensional (3-D) horizontal rectus EOM geometries were obtained from magnetic resonance imaging of five healthy adults, and measured constitutive tissue properties were used. Active and passive strain energies of EOMs were defined using ABAQUS (Dassault Systemes) software. All deformations were assumed to be caused by EOM twitch activation that rotated the eye about a fixed center. The medial rectus (MR) muscle was commanded to additionally contract starting from 26 degrees adducted position, and the lateral rectus (LR) to relax, further adducting the eye either with or without loading by the ON. Tridimensional heat maps were generated to represent the stress and strain distributions.ResultsTensions in the EOMs were physiologically plausible during incremental adduction. Force in the MR increased from 10 gm at 26 degrees adduction to approximately 28 gm at 32 degrees adduction. Under identical MR contraction, adduction with ON loading reached 32 degrees but 36 degrees without it. Maximum and minimum principal strains within the MR were 16% and 22%, respectively, but when ON loading was included, resulting stress and strain were concentrated at the optic disc.ConclusionsThis physiologically plausible method of simulating EOM activation can provide realistic input to model biomechanical behavior of active and passive tissues in the orbit to clarify biomechanical consequences of ON traction during adduction.     

Tracer kinetic modeling of [11C]AFM,a new PET imaging agent for the serotonin transporter

[¹¹C]AFM, or [¹¹C]2-[2-(dimethylaminomethyl)phenylthio]-5-fluoromethylphenylamine, is a new positron emission tomography (PET) radioligand with high affinity and selectivity for the serotonin transporter (SERT). The purpose of this study was to determine the most appropriate kinetic model to quantify [¹¹C]AFM binding in the healthy human brain. Positron emission tomography data and arterial input functions were acquired from 10 subjects. Compartmental modeling and the multilinear analysis-1(MA1) method were tested using the arterial input functions. The one-tissue model showed a lack of fit in low-binding regions, and the two-tissue model failed to estimate parameters reliably. Regional time–activity curves were well described by MA1. The rank order of [¹¹C]AFM binding potential (BP_ND) matched well with the known regional SERT densities. For routine use of [¹¹C]AFM, several noninvasive methods for quantification of regional binding were evaluated, including simplified reference tissue models (SRTM and SRTM2), and multilinear reference tissue models (MRTM and MRTM2). The best methods for region of interest (ROI) analysis were MA1, MRTM2, and SRTM2, with fixed population kinetic values ( or b′) for the reference methods. The MA1 and MRTM2 methods were best for parametric imaging. These results showed that [¹¹C]AFM is a suitable PET radioligand to image and quantify SERT in humans.     

Working alliance predicts psychotherapy outcome even while controlling for prior symptom improvement

Abstract

Objective: Although the working alliance as been found to be a robust predictor of psychotherapy outcome, critics have questioned the causal status of this effect. Specifically, the effect of the alliance may be confounded with the effect of prior symptom improvement. The objective of the present study was to test this possibility. Method: A large dataset from primary care psychotherapy was used to study relationships between alliance and outcome using piecewise multilevel path analysis. Results: Initial symptom level and symptom change up to session three predicted the alliance at session three. Working alliance significantly predicted symptom change rate from session three to termination, even while controlling for several possible confounds. Conclusions: The alliance predicts outcome over and above the effect of prior symptom improvement, supporting a reciprocal influence model of the relationship between alliance and symptom change.     

Defining in vivo dose-response curves for kidney DNA adduct formation of aristolochic acid I in rat,mouse and human by an in vitro and physiologically based kinetic modeling approach

Aristolochic acid I (AAI) is a well-known genotoxic kidney carcinogen. Metabolic conversion of AAI into the DNA-reactive aristolactam-nitrenium ion is involved in the mode of action of tumor formation. This study aims to predict in vivo AAI-DNA adduct formation in the kidney of rat, mouse and human by translating the in vitro concentration-response curves for AAI-DNA adduct formation to the in vivo situation using physiologically based kinetic (PBK) modeling-based reverse dosimetry. DNA adduct formation in kidney proximal tubular LLC-PK1 cells exposed to AAI was quantified by liquid chromatography-electrospray ionization-tandem mass spectrometry. Subsequently, the in vitro concentration-response curves were converted to predicted in vivo dose-response curves in rat, mouse and human kidney using PBK models. Results obtained revealed a dose-dependent increase in AAI-DNA adduct formation in the rat, mouse and human kidney and the predicted DNA adduct levels were generally within an order of magnitude compared with values reported in the literature. It is concluded that the combined in vitro PBK modeling approach provides a novel way to define in vivo dose-response curves for kidney DNA adduct formation in rat, mouse and human and contributes to the reduction, refinement and replacement of animal testing.