Value-directed remembering in first-episode schizophrenia.

OBJECTIVE: Memory deficits in individuals with schizophrenia are well-established, but less is known about how schizophrenia affects metacognitive processes such as metamemory. We investigated metamemory ability using the value-directed remembering task, which assesses the degree to which participants use value cues to guide their learning of a list of items (i.e., their memory selectivity). METHOD: Participants were patients undergoing treatment following a recent first episode of schizophrenia (n = 20) and demographically comparable healthy controls (n = 18). Participants viewed six lists of 24 words where each word was paired with either a low value (1-3 points) or a high value (10-12 points), and they were instructed to maximize their score on free recall tests given after each list. After the final free recall test, participants completed a recognition test where they gave remember/know judgments. RESULTS: On tests of free recall, patients showed reduced memory selectivity relative to healthy controls. On the recognition test, patients failed to show an effect of value on recognition of nonrecalled words, in contrast to healthy controls, who showed a significant value effect that was characterized by greater "remember" judgments. Patients initially overestimated their memory capacity but were able to adjust their estimates to be more accurate based on task experience. Patients' self-reports of memory selectivity were unrelated to their actual memory selectivity. CONCLUSIONS: Patients with first-episode schizophrenia had substantial impairments on the value-directed remembering task, but areas of preserved metamemory ability were also observed. These findings have potential implications for cognitive training interventions. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Effects of Age-Related Stereotype Threat on Metacognition.

Previous work has shown that memory performance in older adults is affected by activation of a stereotype of age-related memory decline. In the present experiment, we examined whether stereotype threat would affect metamemory in older adults; that is, whether under stereotype threat they make poorer judgments about what they could remember. We tested older adults (M Age = 66.18 years) on a task in which participants viewed words paired with point values and "bet" on whether they could later recall each word. If they bet on and recalled a word, they gained those points, but if they bet on and failed to recall a word, they lost those points. Thus, this task required participants to monitor how much they could remember and prioritize high value items. Participants performed this task over six lists of items either under stereotype threat about age-related memory decline or not under stereotype threat. Participants from both groups performed similarly on initial lists, but on later lists, participants under stereotype threat showed impaired performance as indicated by a lower average point score and a lower average gamma coefficient. The results suggest that a modest effect of stereotype threat on recall combined with a modest effect on metacognitive judgments to result in a performance deficit. This pattern of results may reflect an effect of stereotype threat on executive control reducing the ability to strategically use memory.

Early-life stress is associated with a preponderance of habitual responding in a novel instrumental avoidance learning paradigm.

There is substantial evidence linking early-life stress (ELS) to negative health outcomes in adulthood, including addiction. However, the neurocognitive and behavioral mechanisms through which ELS increases these risks remain unclear. To address this gap in knowledge, we developed a novel instrumental learning paradigm to explore the effects of ELS on the balance of habitual versus goal-directed learning. Habits efficiently reproduce repetitive behaviors but are inflexible whenreward contingencies related to those behaviors change. Persisting in performing a response after its outcome has been devalued is the hallmark of habitual behavior in instrumental learning. Participants with a history of higher ELS were significantly more likely to make habitual responses in this instrumental avoidance learning paradigm than individuals with a history of lower ELS. Logistic regression analysis showed that ELS is significantly related to habitual responding over and above the effects of retrospective socioeconomic status, trait and state anxiety, depression and recent levels of stress. Analysis of the differential impacts of the type of ELS suggested that these effects are largely driven by experiences of physical neglect.

Enhanced Avoidance Habits in Relation to History of Early-Life Stress.

The effect of stress on the balance between goal-directed behavior and stimulus-response habits has been demonstrated in a number of studies, but the extent to which stressful events that occur during development affect the balance between these systems later in life is less clear. Here, we examined whether individuals with a history of early-life stress (ELS) show a bias toward avoidance habits on an instrumental learning task as adults. Participants (N = 189 in Experiment 1 and N = 112 in Experiment 2) were undergraduate students at the University of California, Los Angeles. In Experiment 1, we hypothesized that a history of ELS and a longer training phase would be associated with greater avoidance habits. Participants learned to make button-press responses to visual stimuli in order to avoid aversive auditory outcomes. Following a training phase involving extensive practice of the responses, participants were tested for habitual responding using outcome devaluation. After completing the instrumental learning task, participants provided retrospective reports of stressful events they experienced during their first 16 years of life. We did not observe evidence for an effect of the length of training, but we did observe an effect of ELS, with greater stress predicting greater odds of performing the avoidance habit. In Experiment 2, we sought to replicate the effect of ELS observed in Experiment 1, and we also tested whether the presence of distraction during training would increase avoidance habit performance. We replicated the effect of ELS but we did not observe evidence of an effect of distraction. Taken together, these data lend support to the hypothesis that stress occurring during development can have lasting effects on the balance between goal-directed behavior and stimulus-response habits in humans. Enhancement of avoidance habits may help explain the higher levels of negative health outcomes such as heart and liver disease that have been observed in individuals with a history of ELS. Some of the negative health behaviors that contribute to these negative health outcomes, e.g., overeating and substance use, may be performed initially to avoid feelings of distress and then transition to being performed habitually.

Habit Formation and the Striatum.

Data from experimental animals and human subjects has provided convergent evidence for the key role of the striatum in the formation of stimulus-response habits. Habits can be distinguished from associative memories that support goal-directed actions based on their insensitivity to reward devaluation and contingency degradation. Behavior on many instrumental learning tasks can be supported by both declarative knowledge and habits, and these contributions shift with the amount of training. This shift appears to be accompanied by the involvement of different cortico-striatal loops in controlling behavior. Factors that encourage the shift toward and maintenance of habits include learning under conditions of stress, distraction, and interval or probabilistic schedules of reinforcement.

Speed and Rhythm Affect Temporal Structure of Variability in Reaching Poststroke: A Pilot Study.

Temporal structure reveals the potential adaptive strategies employed during upper extremity movements. The authors compared the temporal structure of upper extremity joints under 3 different reaching conditions: preferred speed, fast speed, and reaching with rhythmic auditory cues in 10 individuals poststroke. They also investigated the temporal structure of these 3 reaching conditions in 8 healthy controls to aid in the interpretation of the observed patterns in the poststroke cohort. Approximate entropy (ApEn) was used to measure the temporal structure of the upper extremity joints. ApEn was similar between conditions in controls. After stroke, ApEn was significantly higher for shoulder, elbow, and wrist both at fast speed and with rhythmic cues compared with preferred speed. ApEn at index finger was significantly higher only with rhythmic cues compared with preferred speed. The authors propose that practice reaching at faster speed and with rhythmic cues as a component of rehabilitation interventions may enhance adaptability after stroke.

Putting the brakes on the brakes: negative emotion disrupts cognitive control network functioning and alters subsequent stopping ability.

The ability to inhibit unwanted responses is critical for effective control of behavior, and inhibition failures can have disastrous consequences in real-world situations. Here, we examined how prior exposure to negative emotional stimuli affects the response-stopping network. Participants performed the stop-signal task, which relies on inhibitory control processes, after they viewed blocks of either negatively emotional or neutral images. In Experiment 1, we found that neural activity was reduced following negative image viewing. When participants were required to inhibit responding after neutral image viewing, we observed activation consistent with previous studies using the stop-signal task. However, when participants were required to inhibit responding after negative image viewing, we observed reductions in the activation of ventrolateral prefrontal cortex, dorsolateral prefrontal cortex, medial frontal cortex, and parietal cortex. Furthermore, analysis of neural connectivity during stop-signal task blocks indicated that across participants, emotion-induced changes in behavioral performance were associated with changes in functional connectivity, such that greater behavioral impairment after negative image viewing was associated with greater weakening of connectivity. In Experiment 2, we collected behavioral data from a larger sample of participants and found that stopping performance was impaired after negative image viewing, as seen in longer stop-signal reaction times. The present results demonstrate that negative emotional events can prospectively disrupt the neural network supporting response inhibition.

The effect of early-life stress on memory systems supporting instrumental behavior.

People experiencing early-life stress (ELS) exhibit increased incidence of behaviors that lead to addiction and obesity as adults. Many of these behaviors may be viewed as resulting from an overreliance on habits as opposed to goal-directed instrumental behavior. This increased habitization may result from alterations in the interactions between dorsolateral striatum-dependent and hippocampus-dependent learning systems. As an initial examination of this idea, we investigated the effect of ELS on instrumental learning and extinction. In Experiment 1, we examined the effect of ELS in two groups of people, one trained on a continuous reinforcement schedule and one trained on a partial reinforcement schedule. We found that people who experienced ELS had a diminished effect of the partial reinforcement schedule on extinction. In Experiment 2, we again manipulated reinforcement schedule and also challenged declarative memory by requiring subjects to perform a concurrent task. We found that the declarative challenge did not affect extinction responding in the non-ELS group. In a moderate-ELS group, we observed a diminished sensitivity to the reinforcement schedule during extinction only under divided attention. In the high-ELS group, we observed a reduced sensitivity to reinforcement schedule even in the absence of the declarative memory challenge, consistent with Experiment 1. Our results suggest that ELS reduces the tendency to use declarative, hippocampus-dependent memory in instrumental tasks in favor of habits. ELS may affect hippocampal development, thus altering the interaction between memory systems and potentially contributing to poor health outcomes.

Temporal structure of variability decreases in upper extremity movements post stroke.

BACKGROUND: The objective of this study was to determine movement variability in the more-affected upper-extremity in chronic stroke survivors. We investigated two hypotheses: (1) individuals with stroke will have increased amount of variability and altered structure of variability in upper-extremity joint movement patterns as compared to age-matched controls; and (2) the degree of motor impairment and joint kinematics will be correlated with the temporal structure of variability. METHODS: Sixteen participants with chronic stroke and nine age-matched controls performed three trials of functional reach-to-grasp. The amount of variability was quantified by computing the standard deviation of shoulder, elbow, wrist and index finger flexion/extension joint angles. The temporal structure of variability was determined by calculating approximate entropy in shoulder, elbow, wrist and index finger flexion/extension joint angles. FINDINGS: Individuals with stroke demonstrated greater standard deviations and significantly reduced approximate entropy values as compared to controls. Furthermore, motor impairments and kinematics demonstrated moderate to strong correlations with temporal structure of variability. INTERPRETATION: Changes in the temporal structure of variability in upper-extremity joint angles suggest that movement patterns used by stroke survivors are less adaptable. This knowledge may yield additional insights into the impaired motor system and suggest better interventions that can enhance upper-extremity movement adaptability.

Effect of intense functional task training upon temporal structure of variability of upper extremity post stroke.

STUDY DESIGN: Quasi-experimental design. INTRODUCTION: Although the effectiveness of constraint-induced movement therapy (CIMT) in upper extremity (UE) rehabilitation post stroke is well known, the efficacy of CIMT to enhance the temporal structure of variability in upper extremity movement is not known. PURPOSE: The purpose of this study was to investigate whether CIMT could enhance the temporal structure of variability in upper extremity movement in individuals with chronic stroke. METHODS: Six participants with chronic stroke underwent CIMT for 4 h/day for 2 weeks. Participants performed three trials of functional reach-to-grasp before and after CIMT. Temporal structure of variability was determined by calculating approximate entropy (ApEn) in shoulder, elbow and wrist flexion/extension joint angles. RESULTS: ApEn increased post CIMT, however, statistical significance was not achieved (p > 0.0167). CONCLUSION: Future studies with larger sample size are warranted to investigate the effect of CIMT upon temporal structure of variability in UE movement. LEVEL OF EVIDENCE: 4.

Exploration of patient-centered success criteria and clinically measured improvement during falls rehabilitation.

BACKGROUND AND PURPOSE: One method for defining successful rehabilitation outcomes is to use a threshold of performance on a clinical measure. Patients also have their own criteria for success. The aim of this study was to examine the association between clinical measures and patient criteria for determining successful intervention. METHODS: Twenty-two participants participated in a 12-week intervention program for balance disorders. Participants were tested using the Berg balance scale (BBS) and dynamic gait index (DGI) at the first and final visits. They also used the patient's perspective outcomes questionnaire (PPOQ) at the first visit to rate impairments in the core domains from the international classification of Function. Participants rated their usual levels of impairment across domains, their desired levels of impairment after intervention (success criteria), and how important it was to change in each domain. At the final visit, all participants used the PPOQ to rate their current impairment across domains and completed a 15-point global rating of change (GRC). The intervention was defined as a success if the participant rated himself or herself as "a great deal" or "a very great deal" better using the GRC. Changes in the BBS and the DGI were dichotomized on the basis of whether the change exceeded the minimal detectable change (MDC) of the instrument. Participants' ratings of impairment at 12 weeks were compared with their success criteria and dichotomized on the basis of whether the success criteria had been met. The Freidman test was used to test differences across domains at baseline with Wilcoxon tests for follow-up. Wilcoxon tests were also used to examine the importance of change across domains. Chi-square tests were used to explore the association among the GRC, performance on clinical tests, and whether success criteria were met. RESULTS: Significant changes were noted for the group for both BBS (P < .001) and DGI (P = .006). Only 40% of participants exceeded or met their desired or expected change in impairment for mobility. No significant associations were noted between exceeding MDC on the BBS or DGI and any of the domains on the PPOQ (all Ps = .263). Bivariate associations were noted between baseline measures of psychological factors and many of the participant ratings of impairment. Fifty-five percent of participants indicated that they were a great deal better or a very great deal better. Significant association was identified between success and exceeding MDC on the BBS (χ = 5.84, P = .016) but not the DGI. When considering participants' desired change in impairment, only meeting desired changes in mental function was associated with considering the intervention a success (χ = 4.55, P = .033). DISCUSSION: Treatment success from the perspective of this group of older adults was related to improvement on a clinic-based performance measure and not the participants' intrinsic success criteria assessed at the beginning of the intervention. CONCLUSION: Making measurable change in gait and balance translates into perceived success for the patient with a balance disorder.

Reliability of upper extremity kinematics while performing different tasks in individuals with stroke.

Assessments of upper extremity performance typically include qualitative rather than quantitative measures of functional ability. Kinematic analysis is an objective, discriminative measure that quantifies movement biomechanics; however, the use within the poststroke impaired upper extremity is not well established. The purpose of this study was to examine the reliability of upper extremity kinematics in 18 individuals with stroke and 9 healthy controls. Participants performed reaching and grasping tasks over 2 separate days and metrics included movement time, peak velocity, index of curvature, trunk displacement, maximum aperture, and percentage of the movement cycle where maximum aperture occurred. The results showed moderate to high intraclass correlation and low standard error of measurement values for most variables, demonstrating that kinematic analysis may be a feasible and useful tool to quantify upper extremity movement after stroke.

Speed- and cane-related alterations in gait parameters in individuals with multiple sclerosis.

Previous literature reporting gait parameters in the MS population has largely focused on preferred walking speed without the use of an assistive device. However, these data may not fully represent daily activity, as individuals with MS vary their speed or use a cane when walking. In this exploratory study, 11 MS participants and 13 controls walked at both maximal and preferred speed for a distance of 25-feet. Participants with MS that used a cane daily (n=6) were asked to complete additional trials with their cane. When walking unassisted at both speeds, MS participants displayed significantly reduced velocity, cadence, stride length, step length ratio, single support and swing time, as well as increased double support and stance time compared to controls. Cane use resulted in significantly higher velocities when walking at maximal speeds, and showed significantly improved variability, gait asymmetry, and bilateral coordination at preferred walking speed. In conclusion, the use of a cane may significantly improve gait for individuals with MS. Furthermore, gait parameters should be measured at both maximal and preferred speeds, with and without a cane, as its use may mask underlying gait impairment.

Feasibility of entrainment with ankle mechanical perturbation to treat locomotor deficit of neurologically impaired patients.

Entraining human gait with periodic torque from a robot may provide a novel approach to robot-aided walking therapy that is competent to exploit the natural oscillating dynamics of human walking. To test the feasibility of this strategy we applied a periodic ankle torque to neurologically impaired patients (one with stroke and one with multiple sclerosis). As observed in normal human walking, both patients adapted their gait periods to synchronize with the perturbation by phase-locking the robotic torque at terminal stance phase. In addition, their gait cadence became significantly faster due to the training with clear after effects when the perturbation ceased. These results support a new strategy for walking therapy that exploits an embedded neural oscillator interacting with peripheral mechanics and the resulting natural dynamics of walking, which are essential but hitherto neglected elements of walking therapy.

Static ankle impedance in stroke and multiple sclerosis: a feasibility study.

Quantitative characterization of ankle mechanical impedance is critical for understanding lower extremity function in persons with neurological disorders. In this paper, we examine the feasibility of employing an ankle robot and multivariable analysis to determine static ankle impedance in 4 patients: 1 with multiple sclerosis and 3 with stroke. We employed a scalar based vector field approximation method which was successful in identifying young healthy subjects' ankle impedance. It enabled clear interpretation of spatial ankle impedance structure and intermuscular feedback at the ankle for both affected and unaffected legs. Measured impedance of two patients was comparable to healthy young subjects, while the other two patients had significantly different static ankle impedance properties.

Reduction of freezing of gait in Parkinson's disease by repetitive robot-assisted treadmill training: a pilot study.

BACKGROUND: Parkinson's disease is a chronic, neurodegenerative disease characterized by gait abnormalities. Freezing of gait (FOG), an episodic inability to generate effective stepping, is reported as one of the most disabling and distressing parkinsonian symptoms. While there are no specific therapies to treat FOG, some external physical cues may alleviate these types of motor disruptions. The purpose of this study was to examine the potential effect of continuous physical cueing using robot-assisted sensorimotor gait training on reducing FOG episodes and improving gait. METHODS: Four individuals with Parkinson's disease and FOG symptoms received ten 30-minute sessions of robot-assisted gait training (Lokomat) to facilitate repetitive, rhythmic, and alternating bilateral lower extremity movements. Outcomes included the FOG-Questionnaire, a clinician-rated video FOG score, spatiotemporal measures of gait, and the Parkinson's Disease Questionnaire-39 quality of life measure. RESULTS: All participants showed a reduction in FOG both by self-report and clinician-rated scoring upon completion of training. Improvements were also observed in gait velocity, stride length, rhythmicity, and coordination. CONCLUSIONS: This pilot study suggests that robot-assisted gait training may be a feasible and effective method of reducing FOG and improving gait. Videotaped scoring of FOG has the potential advantage of providing additional data to complement FOG self-report.

Improved fall-related efficacy in older adults related to changes in dynamic gait ability.

BACKGROUND: Low fall-related efficacy is associated with the number and severity of future falls in older adults with balance disorders. OBJECTIVE: The purpose of this study was to examine whether improvements in clinical measures of balance after an intervention program were associated with changes in efficacy. DESIGN: A prospective, nonexperimental, pretest-posttest design was used. METHODS: Sixty-three people (43 men, 20 women; mean [±SD] age=76.6±4.9 years) with a history of at least 2 falls in the previous 12 months were enrolled between 2004 and 2008 to participate in a 12-week home exercise program. Balance deficits were identified using the Berg Balance Scale (BBS) and the Dynamic Gait Index (DGI), and participants were evaluated monthly. Hierarchical linear regression was used to assess the relationship between measures of balance (BBS and DGI) and efficacy (Falls Efficacy Scale) before intervention. A second model examined the relationship between changes in balance and changes in efficacy after participation in the program. RESULTS: Preintervention scores of efficacy were significantly associated with age, depression, and BBS and DGI scores. After controlling for age, depression, and strength (force-generating capacity), BBS and DGI scores together accounted for 34% of the variance in preintervention efficacy. Significant improvements were noted in efficacy, BBS and DGI scores, and depression after intervention. When controlling for preintervention efficacy and changes in depression, the changes in DGI and BBS scores together explained 11% of the variance in the change in fall-related efficacy; however, only DGI scores contributed uniquely. Limitations These results are tempered by the absence of a control group to examine the role of time on changes in efficacy. CONCLUSIONS: The results suggest that increased emphasis on mobility during rehabilitation leads to improved confidence to perform activities of daily living without falling.

Response to intensive upper extremity therapy by individuals with ataxia from stroke.

OBJECTIVE: This study investigated whether or not individuals with ataxia from stroke improve their upper extremity motor function with intense motor practice. METHOD: Three individuals with ataxia from chronic stroke completed modified constraint-induced movement therapy (CIMT) protocols. Stroke Participants 1 and 2 completed 60 hours and Stroke Participant 3 completed 30 hours of graded task practice while being asked to wear a mitt on the nonparetic arm for 90% of waking hours. Outcome measures were the upper extremity subscale of the Fugl-Meyer Motor Assessment, Wolf Motor Function Test, Motor Activity Log, and kinematics of reaching. RESULTS: All stroke participants improved on either the Fugl-Meyer or the Wolf tests and increased their daily use of the paretic upper extremity. Participants 1 and 2 also improved on all kinematic measures: maximum velocity and time to maximum velocity increased, while index of curvature, number of peaks in the velocity profile, and trunk movement decreased. Participant 3 improved on some kinematic measures (smoother velocity profile, increased time to maximum velocity, decreased number of peaks in the velocity profile) but not all (decreased maximum velocity, increased index of curvature). CONCLUSION: Individuals with ataxia from stroke can improve their motor function with intense motor practice.

Descriptive characteristics as potential predictors of outcomes following constraint-induced movement therapy for people after stroke.

BACKGROUND AND PURPOSE: Limited evidence exists regarding the characteristics of people who benefit most from constraint-induced movement therapy (CIMT). This study's purpose was to investigate 6 potential descriptors in predicting CIMT outcomes. SUBJECTS: The participants were a convenience sample (N=55) of people who were more than 6 months poststroke. METHODS: The Wolf Motor Function Test (WMFT) and the Motor Activity Log amount scale (MALa) were used to assess outcomes for CIMT. The potential predictors (side of stroke, time since stroke, hand dominance, age, sex, and ambulatory status) were entered into a linear regression model using stepwise entry, with simultaneous entry of the dependent variables' pretest scores as the covariate. RESULTS: Age was the only significant predictor of the 6 potential predictors in the model and was predictive only of MALa scores. None of the independent variables showed a predictive relationship with the WMFT. DISCUSSION AND CONCLUSION: Although age was the only significant predictor, an equally strong finding in this study was that side of stroke, chronicity, hand dominance, sex, and ambulatory status were not found to be predictors at the follow-up session. This finding emphasizes the importance of not excluding people from CIMT based on these predictors.

Active finger extension predicts outcomes after constraint-induced movement therapy for individuals with hemiparesis after stroke.

BACKGROUND AND PURPOSE: Constraint-induced movement therapy (CIMT) is a rehabilitative strategy used primarily with the post-stroke population to increase the functional use of the neurologically weaker upper extremity through massed practice while restraining the lesser involved upper extremity. Whereas research evidence supports CIMT, limited evidence exists regarding the characteristics of individuals who benefit most from this intervention. The goal of this study was to investigate the potential of 5 measures to predict functional CIMT outcomes. METHODS: A convenience sample of 55 individuals, >6 months after stroke, was recruited that met specific inclusion/exclusion criteria allowing for individuals whose upper extremity was mildly to severely involved. They participated in CIMT 6 hours per day. Pretest, post-test, and follow-up assessments were performed to assess the outcomes for the Wolf Motor Function Test (WMFT). The potential predictors were minimal motor criteria (active extension of the wrist and 3 fingers), active finger extension/grasp release, grip strength, Fugl-Meyer upper extremity motor score, and the Frenchay score. A step-wise regression analysis was used in which the potential predictors were entered in a linear regression model with simultaneous entry of the dependent variables' pretest score as the covariate. Two regressions models were determined for the dependent variable, for immediate post-test, and for follow-up post-test. RESULTS: Finger extension was the only significant predictor of WMFT outcomes. CONCLUSIONS: When using finger extension/grasp release as a predictor in the regression equations, one can predict individual's follow-up scores for CIMT. This experiment provides the most comprehensive investigation of predictors of CIMT outcomes to date.