Neural processes related to negative self-concept in adult and adolescent anorexia nervosa.

OBJECTIVE: Negative self-concept is characteristic of anorexia nervosa (AN), but the neural processes mediating this component of AN is unknown. These studies investigated how valence and social perspectives impact neural processing in both adults and adolescents with AN. METHOD: In an fMRI task, participants evaluated positive and negative adjectives from three social perspectives. Two studies were completed, one in 59 women (healthy, with AN, recovered from AN) and one in 42 adolescents (healthy, with AN). Neural regions of interest (ROIs) related to valence were identified and activations compared across groups and social perspectives. RESULTS: Behaviourally, both adult and adolescent cohorts with AN were less positive during self-evaluations. In the adult study, neural differences related to clinical group and condition were observed in ROIs more responsive to positive social stimuli (medial prefrontal cortex, precuneus, left temporoparietal junction) but not in ROIs more responsive to negative social stimuli. No neural differences in relation to clinical group were observed in the adolescents. CONCLUSIONS: Behavioural differences related to negative self-concept are present in both adolescents and adults with AN, and neural differences, selective for positive social stimuli, were also observed in adults. AN may interfere with neurodevelopmental processes involved in positive self-concept.

Navigating Increasing Levels of Relational Complexity: Perceptual, Analogical, and System Mappings.

Relational thinking involves comparing abstract relationships between mental representations that vary in complexity; however, this complexity is rarely made explicit during everyday comparisons. This study explored how people naturally navigate relational complexity and interference using a novel relational match-to-sample (RMTS) task with both minimal and relationally directed instruction to observe changes in performance across three levels of relational complexity: perceptual, analogy, and system mappings. Individual working memory and relational abilities were examined to understand RMTS performance and susceptibility to interfering relational structures. Trials were presented without practice across four blocks, and participants received feedback after each attempt to guide learning. Experiment 1 instructed participants to select the target that best matched the sample, whereas Experiment 2 additionally directed participants' attention to same and different relations. Participants in Experiment 2 demonstrated improved performance when solving analogical mappings, suggesting that directing attention to relational characteristics affected behavior. Higher performing participants-those with above-chance performance on the final block of system mappings-solved more analogical RMTS problems and had greater visuospatial working memory, abstraction, verbal analogy, and scene analogy scores compared to lower performers. Lower performers were less dynamic in their performance across blocks and demonstrated negative relationships between analogy and system mapping accuracy, suggesting increased interference between these relational structures. Participant performance on RMTS problems did not change monotonically with relational complexity, suggesting that increases in relational complexity places nonlinear demands on working memory. We argue that competing relational information causes additional interference, especially in individuals with lower executive function abilities.

Are the advantages of chess expertise on visuo-spatial working-memory capacity domain specific or domain general?

Chess experts have repeatedly demonstrated exceptional recall of chessboards, which is weakened by disruption of the chessboard. However, chess experts still perform better than novices when recalling such disrupted chessboards, suggesting a somewhat generalized expertise effect. In the current study, we examined the extent of this generalized expertise effect on early processing of visuo-spatial working memory (VSWM), by comparing 14 chess experts (Elo rating > 2000) and 15 novices on a change-detection paradigm using disrupted chessboards, where attention had to be selectively deployed to either visual or spatial features, or divided across both features. The paradigm differed in the stimuli used (domain-specific chess pieces vs. novel visual shapes) to evaluate domain-general effects of chess expertise. Both experts and novices had greater memory discriminability for chess stimuli than for the unfamiliar stimuli, suggesting a salience advantage for familiar stimuli. Experts, however, demonstrated better memory discriminability than novices not only for chess stimuli presented on these disrupted chessboards, but also for novel, domain-general stimuli, particularly when detecting spatial changes. This expertise advantage was greater for chessboards with supra-capacity set sizes. For set sizes within the working-memory capacity, the expertise advantage was driven by enhanced selective attention to spatial features by chess experts when compared to visual features. However, any expertise-related VSWM advantage disappeared in the absence of the 8 × 8 chessboard display, which implicates the chessboard display as an essential perceptual aspect facilitating the "expert memory effect" in chess, albeit one that might generalize beyond strictly domain-relevant stimuli.

Neural correlates of reduced depressive symptoms following cognitive training for chronic traumatic brain injury.

Depression is the most frequent comorbid psychiatric condition among individuals with traumatic brain injury (TBI). Yet, little is known about changes in the brain associated with reduced depressive symptoms following rehabilitation for TBI. We identified whether cognitive training alleviates comorbid depressive symptoms in chronic TBI (>6 months post-injury) as a secondary effect. Further, we elucidated neural correlates of alleviated depressive symptoms following cognitive training. A total of seventy-nine individuals with chronic TBI (53 depressed and 26 non-depressed individuals, measured using the Beck Depressive Inventory [BDI]), underwent either strategy- or information-based cognitive training in a small group for 8 weeks. We measured psychological functioning scores, cortical thickness, and resting-state functional connectivity (rsFC) for these individuals before training, immediately post-training, and 3 months post-training. After confirming that changes in BDI scores were independent of training group affiliation, we identified that the depressive-symptoms group showed reductions in BDI scores over time relative to the non-depressed TBI controls (p < .01). Within the depressive-symptoms group, reduced BDI scores was associated with improvements in scores for post-traumatic stress disorder, TBI symptom awareness, and functional status (p < .00625), increases in cortical thickness in four regions within the right prefrontal cortex (pvertex  < .01, pcluster <.05), and decreases in rsFC with each of these four prefrontal regions (pvertex  < .01, pcluster  < .0125). Overall, these findings suggest that cognitive training can reduce depressive symptoms in TBI even when the training does not directly target psychiatric symptoms. Importantly, cortical thickness and brain connectivity may offer promising neuroimaging markers of training-induced improvement in mental health status in TBI.

Calibrated imaging reveals altered grey matter metabolism related to white matter microstructure and symptom severity in multiple sclerosis.

Multiple sclerosis (MS) involves damage to white matter microstructures. This damage has been related to grey matter function as measured by standard, physiologically-nonspecific neuroimaging indices (i.e., blood-oxygen-level dependent signal [BOLD]). Here, we used calibrated functional magnetic resonance imaging and diffusion tensor imaging to examine the extent to which specific, evoked grey matter physiological processes were associated with white matter diffusion in MS. Evoked changes in BOLD, cerebral blood flow (CBF), and oxygen metabolism (CMRO2 ) were measured in visual cortex. Individual differences in the diffusion tensor measure, radial diffusivity, within occipital tracts were strongly associated with MS patients' BOLD and CMRO2 . However, these relationships were in opposite directions, complicating the interpretation of the relationship between BOLD and white matter microstructural damage in MS. CMRO2 was strongly associated with individual differences in patients' fatigue and neurological disability, suggesting that alterations to evoked oxygen metabolic processes may be taken as a marker for primary symptoms of MS. This work demonstrates the first application of calibrated and diffusion imaging together and details the first application of calibrated functional MRI in a neurological population. Results lend support for neuroenergetic hypotheses of MS pathophysiology and provide an initial demonstration of the utility of evoked oxygen metabolism signals for neurology research. Hum Brain Mapp 38:5375-5390, 2017. © 2017 Wiley Periodicals, Inc.

Disrupted Intrinsic Connectivity among Default, Dorsal Attention, and Frontoparietal Control Networks in Individuals with Chronic Traumatic Brain Injury.

OBJECTIVES: Individuals with chronic traumatic brain injury (TBI) often show detrimental deficits in higher order cognitive functions requiring coordination of multiple brain networks. Although assessing TBI-related deficits in higher order cognition in the context of network dysfunction is promising, few studies have systematically investigated altered interactions among multiple networks in chronic TBI. METHOD: We characterized disrupted resting-state functional connectivity of the default mode network (DMN), dorsal attention network (DAN), and frontoparietal control network (FPCN) whose interactions are required for internally and externally focused goal-directed cognition in chronic TBI. Specifically, we compared the network interactions of 40 chronic TBI individuals (8 years post-injury on average) with those of 17 healthy individuals matched for gender, age, and years of education. RESULTS: The network-based statistic (NBS) on DMN-DAN-FPCN connectivity of these groups revealed statistically significant (p NBS2.58) reductions in within-DMN, within-FPCN, DMN-DAN, and DMN-FPCN connectivity of the TBI group over healthy controls. Importantly, such disruptions occurred prominently in between-network connectivity. Subsequent analyses further exhibited the disrupted connectivity patterns of the chronic TBI group occurring preferentially in long-range and inter-hemispheric connectivity of DMN-DAN-FPCN. Most importantly, graph-theoretic analysis demonstrated relative reductions in global, local and cost efficiency (p<.05) as a consequence of the network disruption patterns in the TBI group. CONCLUSION: Our findings suggest that assessing multiple networks-of-interest simultaneously will allow us to better understand deficits in goal-directed cognition and other higher order cognitive phenomena in chronic TBI. Future research will be needed to better understand the behavioral consequences related to these network disruptions.

Modulation of working memory function by motivation through loss-aversion.

Cognitive performance is affected by motivation. Few studies, however, have investigated the neural mechanisms of the influence of motivation through potential monetary punishment on working memory. We employed functional MRI during a delayed recognition task that manipulated top-down control demands with added monetary incentives to some trials in the form of potential losses of bonus money. Behavioral performance on the task was influenced by loss-threatening incentives in the form of faster and more accurate performance. As shown previously, we found enhancement of activity for relevant stimuli occurs throughout all task periods (e.g., stimulus encoding, maintenance, and response) in both prefrontal and visual association cortex. Further, these activation patterns were enhanced for trials with possible monetary loss relative to nonincentive trials. During the incentive cue, the amygdala and striatum showed significantly greater activation when money was at a possible loss on the trial. We also evaluated patterns of functional connectivity between regions responsive to monetary consequences and prefrontal areas responsive to the task. This analysis revealed greater delay period connectivity between and the left insula and prefrontal cortex with possible monetary loss relative to nonincentive trials. Overall, these results reveal that incentive motivation can modulate performance on working memory tasks through top-down signals via amplification of activity within prefrontal and visual association regions selective to processing the perceptual inputs of the stimuli to be remembered.

Impaired neural processing of social attribution in anorexia nervosa.

Anorexia nervosa (AN) patients have been found to have problems in social cognition, including the process of thinking about other people's thoughts and feelings, often referred to as Theory of Mind (ToM). We examined neural correlates relating to thinking about social relationships in 17 women in recovery from anorexia (RAN) and 17 healthy women (CON) using a functional magnetic resonance imaging (fMRI) task. The task consisted of short videos of moving shapes that subjects viewed either in the context of performing a social decision related to how the shapes interacted: "People: All friends?" or in the context of performing a visuospatial task related to how the shapes moved after bumping into each other: "Bumper cars: Same weight?". The RAN participants showed reduced activation in the social cognition network, with the most robust differences in the right temporoparietal junction (RTPJ). There were no significant differences between the CON and RAN groups in regions more active during the visuospatial task. These neural correlates show differences in the processing of social knowledge in RAN subjects suggesting that biological impairments in social cognition may contribute to pathology in AN.

Efficacy of Cognitive Training When Translated From the Laboratory to the Real World.

INTRODUCTION: Research shows that cognitive performance and emotional well-being can be significantly strengthened. A high-performance brain training protocol, Strategic Memory Advanced Reasoning Training (SMART), was developed by cognitive neuroscientists at The University of Texas at Dallas Center for BrainHealth based on 25-plus years of scientific study. Randomized controlled trials with various populations have shown that training and use of nine "SMART" strategies for processing information can improve cognitive performance and psychological health. However, the multi-week intensive training used in the laboratory is not practical for widespread use outside the laboratory. This article examines the efficacy of SMART when translated outside the laboratory to two populations (military/veterans and law enforcement) that received SMART in condensed time frames. MATERIALS AND METHODS: In two translation studies with healthy military personnel and veterans, 425 participants received between 6 and 10 hours of SMART over 2 days. In a third translation study, 74 healthy police officers received 9 hours of SMART over 3 days. Training was conducted by clinicians who taught the nine "SMART" strategies related to three core areas-strategic attention, integrated reasoning, and innovation-to groups of up to 25 participants. In all three translation studies, cognitive performance and psychological health data were collected before and immediately following the training. In one of the military/veteran studies, psychological health data were also collected 1 and 4 months following the training. RESULTS: In both translations to military personnel and veterans, there were improvements in the complex cognitive domains of integrated reasoning (P < .0001) and innovation (P < .0001) immediately after undergoing SMART. In the translation to police officers, there were improvements in the cognitive domains of innovation (P = .02) and strategic attention (P = .005). Participants in all three translations saw statistically significant improvements in self-reported symptoms of psychological health. The improvements continued among a subset of participants who responded to the later requests for information. CONCLUSIONS: The results of translating to these two populations provide evidence supporting the efficacy of SMART delivered in an abbreviated time frame. The improvements in two major domains of cognitive function demonstrate that strategies can be taught and immediately applied by those receiving the training. The immediate psychological health improvements may be transient; however, the continued improvements in psychological health observed in a subset of the participants suggest that benefits may be sustainable even at later intervals.

Estimates of brain age for gray matter and white matter in younger and older adults: Insights into human intelligence.

Aging entails a multifaceted complex of changes in macro- and micro-structural properties of human brain gray matter (GM) and white matter (WM) tissues, as well as in intellectual abilities. To better capture tissue-specific brain aging, we combined volume and distribution properties of diffusivity indices to derive subject-specific age scores for each tissue. We compared age-related variance between younger and older adults for GM and WM age scores, and tested whether tissue-specific age scores could explain different effects of aging on fluid (Gf) and crystalized (Gc) intelligence in younger and older adults. Chronological age was strongly associated with GM (R2 = 0.73) and WM (R2 = 0.57) age scores. The GM age score accounted for significantly more variance in chronological age in younger relative to older adults (p < 0.001), whereas the WM age score accounted for significantly more variance in chronological age in older compared to younger adults (p < 0.025). Consistent with existing literature, younger adults outperformed older adults in Gf while older adults outperformed younger adults in Gc. The GM age score was negatively associated with Gf in younger adults (p < 0.02), whereas the WM age score was negatively associated with Gc in older adults (p < 0.02). Our results provide evidence for differences in the effects of age on GM and WM in younger versus older adults that may contribute to age-related differences in Gf and Gc.

Cognitive Training Reorganizes Network Modularity in Traumatic Brain Injury.

Background. Graph-theoretic approaches are increasingly popular for identifying the patterns of disrupted neural systems after traumatic brain injury (TBI). However, the patterns of neuroplasticity in brain organization after cognitive training in TBI are less well understood. Objective. We identified the patterns of training-induced neuroplasticity of the whole-brain network in TBI, using resting-state functional connectivity and graph theory. Methods. A total of 64 civilians and veterans with TBI were randomized into either a strategy-based cognitive training group (n = 33) or a knowledge-based training group (active control group; n = 31) for 8 weeks. The participants experienced mild to severe TBI without focal damage and persistent cognitive dysfunctions. A subset of participants complained of subclinical but residual psychiatric symptoms. We acquired their resting-state functional magnetic resonance imaging before training, immediately posttraining, and 3 months posttraining. From participants' resting-state networks, we obtained the modularity, participation coefficient, within-module connectivity, global efficiency, and local efficiency over multiple network densities. We next performed longitudinal analyses on those measures corrected for multiple comparisons across network densities using false discovery rate (FDR). Results. Relative to the knowledge-based training group, the strategy-based cognitive training group had reduced modularity and increased participation coefficient, global efficiency, and local efficiency over time (Pnodal < .05; qFDR < 0.05). Brain behavior analysis revealed that the participation coefficient and global efficiency within the strategy-based cognitive training group correlated with trail-making scores in the context of training (Pnodal < .05; qFDR < 0.05). Conclusions. Cognitive training reorganized modular networks in TBI over the whole brain. Graph-theoretic approaches may be useful in identifying a potential brain-based marker of training efficacy in TBI.

The influence of oxytocin and vasopressin on men's judgments of social dominance and trustworthiness: An fMRI study of neutral faces.

Cues signaling trust and dominance are crucial for social life. Previous studies on the effects of oxytocin (OT) nasal sprays on trustworthiness evaluations have been inconsistent and its influence on dominance is unknown. Vasopressin (AVP) may also influence social cue perception, but even fewer investigations have evaluated this possibility. We evaluated the effects of intranasal OT and AVP compared to placebo control during three double-blinded functional magnetic resonance imaging sessions. Twenty males received a pseudo-randomized order of nasal spray conditions and rated the trustworthiness and dominance of neutral faces. OT increased facial dominance ratings compared to placebo. Neuroimaging results revealed an inverse relationship between brain activation and face ratings for OT compared to placebo in regions involved in processing emotional expressions. Specifically, the right superior temporal gyrus was attenuated as ratings increased and the left precuneus selectively diminished with increasing dominance ratings. Additionally, OT increased functional connectivity between frontoparietal regions and the right amygdala for faces rated as highly dominant, but OT increased connectivity between the fusiform gyrus, hippocampus, and bilateral ventral tegmental area (VTA) for faces perceived as highly trustworthy. Overall, OT increased the perception of dominance but did not influence trustworthiness judgments. However, we observed regional neural effects for OT that differed between judgments of trustworthiness and dominance. AVP attenuated left temporoparietal junction activity as face ratings increased, a result consistent with AVP influencing mentalization. AVP also led to increased left amygdala and right VTA connectivity with the putamen, which is consistent with cue-driven, habitual responses.

Executive function training in chronic traumatic brain injury patients: study protocol.

BACKGROUND: Some individuals who sustain traumatic brain injuries (TBIs) continue to experience significant cognitive impairments chronically (months to years post injury). Many tests of executive function are insensitive to these executive function impairments, as such impairments may only appear during complex daily life conditions. Daily life often requires us to divide our attention and focus on abstract goals. In the current study, we compare the effects of two 1-month electronic cognitive rehabilitation programs for individuals with chronic TBI. The active program (Expedition: Strategic Advantage) focuses on improving goal-directed executive functions including working memory, planning, long-term memory, and inhibitory control by challenging participants to accomplish life-like cognitive simulations. The challenge level of the simulations increases in accordance with participant achievement. The control intervention (Expedition: Informational Advantage) is identical to the active program; however, the cognitive demand level is capped, preventing participants from advancing beyond a set level. We will evaluate these interventions with a military veteran TBI population. METHODS/DESIGN: One hundred individuals will be enrolled in this double-blinded clinical trial (all participants and testers are blinded to condition). Each individual will be randomly assigned to one of two interventions. The primary anticipated outcomes are improvement of daily life cognitive function skills and daily life functions. These are measured by a daily life performance task, which tests cognitive skills, and a survey that evaluates daily life functions. Secondary outcomes are also predicted to include improvements in working memory, attention, planning, and inhibitory control as measured by a neuropsychological test battery. Lastly, neuroimaging measures will be used to evaluate changes in brain networks supporting cognition pre and post intervention. DISCUSSION: We will test whether electronically delivered cognitive rehabilitation aimed at improving daily life functional skills will provide cognitive and daily life functional improvements for individuals in the chronic phase of TBI recovery (greater than 3 months post injury). We aim to better understand the cognitive processes involved in recovery and the characteristics of individuals most likely to benefit. This study will also address the potential to observe generalizability or to transfer from a software-based cognitive training tool toward daily life improvement. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03704116 . Retrospectively registered on 12 Oct 2018.

Distraction during relational reasoning: the role of prefrontal cortex in interference control.

We compared the reasoning performance of patients with frontal-variant frontotemporal lobar degeneration (FTLD) with that of patients with temporal-variant FTLD and healthy controls. In a picture analogy task with a multiple-choice answer format, frontal-variant FTLD patients performed less accurately than temporal-variant FTLD patients, who in turn performed worse than healthy controls, when semantic and perceptual distractors were present among the answer choices. When the distractor answer choices were eliminated, frontal-variant patients showed relatively greater improvement in performance. Similar patient groups were tested with a relational-pattern reasoning task that included manipulations of one or two relations and both perceptual and semantic extraneous information. Frontal-variant patients showed performance deficits on all tasks relative to the other subject groups, especially when distracted. These results demonstrate that intact prefrontal cortex (PFC) is necessary for controlling interference from perceptual and semantic distractors in order to reason from relational structure.

Neuroplasticity of cognitive control networks following cognitive training for chronic traumatic brain injury.

Cognitive control is the ability to coordinate thoughts and actions to achieve goals. Cognitive control impairments are one of the most persistent and devastating sequalae of traumatic brain injuries (TBI). There have been efforts to improve cognitive control in individuals with post-acute TBI. Several studies have reported changes in neuropsychological measures suggesting the efficacy of cognitive training in improving cognitive control. Yet, the neural substrates of improved cognitive control after training remains poorly understood. In the current study, we identified neural plasticity induced by cognitive control training for TBI using resting-state functional connectivity (rsFC). Fifty-six individuals with chronic mild TBI (9 years post-injury on average) were randomized into either a strategy-based cognitive training group (N = 26) or a knowledge-based training group (active control condition; N = 30) for 8 weeks. We acquired a total of 109 resting-state functional magnetic resonance imaging from 45 individuals before training, immediately post-training, and 3 months post-training. Relative to the controls, the strategy-based cognitive training group showed monotonic increases in connectivity in two cognitive control networks (i.e., cingulo-opercular and fronto-parietal networks) across time points in multiple brain regions (pvoxel < 0.001, pcluster < 0.05). Analyses of brain-behavior relationships revealed that fronto-parietal network connectivity over three time points within the strategy-based cognitive training group was positively associated with the trail making scores (pvoxel < 0.001, pcluster < 0.05). These findings suggest that training-induced neuroplasticity continues through chronic phases of TBI and that rsFC can serve as a neuroimaging biomarker of evaluating the efficacy of cognitive training for TBI.

Oxytocin Receptor Polymorphism Decreases Midline Neural Activations to Social Stimuli in Anorexia Nervosa.

Oxytocin is a neurotransmitter related to both feeding and social behavior; anorexia nervosa is a psychiatric illness defined by reduced food intake, weight loss, and problems in social perceptions. Oxytocin receptor single nucleotide polymorphisms rs2254298 or rs53576 and neural responses to social stimuli were evaluated in adult women with or recovered from anorexia nervosa using functional magnetic resonance imaging. Carriers of the A allele for OXTR rs2254298 (2 AA and 10 AG) showed significantly reduced activation of portions of the posterior cingulate cortex and medial prefrontal cortex for social stimuli as well as greater negative connectivity between the posterior cingulate and the occipital lobe relative to the GG subjects for rs2254298. Differences in the other OXTR SNP, rs53576, did not result in detectable neural differences in either whole brain or region of interest analyses. Development of a mechanistic, biological model of how social behavior is impacted by mental illness requires linking genes to functional brain activations in disease. This pilot study suggests that in anorexia nervosa, differences related to OXTR SNP rs2254298 may alter neural responses to social stimuli and disrupt the engagement and disengagement of the default mode network.

A method for characterizing semantic and lexical properties of sentence completions in traumatic brain injury.

Clinical investigations of individuals with chronic stage traumatic brain injury (TBI) showing mild-to-moderate levels of residual impairment largely use standardized neuropsychological assessments to measure executive functioning. The Hayling Sentence Completion Test (HSCT) relies upon several executive functions but detects cognitive impairments across studies inconsistently. We sought to (a) further characterize sentence completions on the HSCT by quantifying their semantic and lexical properties and (b) investigate cognitive components important for HSCT performance. A sample of 108 mild-to-moderate participants with TBI underwent a comprehensive neuropsychological assessment that evaluated verbal ability, working memory, processing speed, task switching, and inhibitory control. Multiple regression analyses suggest that these 5 cognitive components differentially contribute to describing HSCT performance and measures of semantic and lexical properties of unconnected sentence completions. Across all 3 measures, verbal ability was most predictive of performance, while inhibitory control was the least predictive. Working memory capacity also predicted HSCT performance, while processing speed and task switching ability predicted lexical measures. We present a method for quantitatively measuring the semantic and lexical properties of generated words on the HSCT and how these additional measures relate to executive functions. (PsycINFO Database Record

Reward modulation of prefrontal and visual association cortex during an incentive working memory task.

Cognitive performance differs with motivation, but little direct evidence exists regarding the neural mechanisms of the influence of reward motivation on working memory (WM). We tested the effects of motivation on the top-down control in visual WM. Encoding relevant stimuli for maintenance, while suppressing inappropriate inputs is considered a core process in cognition. Prior functional magnetic resonance imaging (fMRI) results demonstrated that stimulus-specific visual association cortex serves as a marker of activation differences for task-relevant and task-irrelevant inputs, such that enhanced activity occurs when attention is directed to relevant stimuli and suppressed activity occurs when attention is directed away from irrelevant stimuli [Gazzaley, A., Cooney, J., McEvoy, K., Knight, R.T., and D'Esposito, M. J. Cogn. Neurosci. 17, 507-517]. We used fMRI to test whether differential WM performance, indexed by lowered response times on a delayed-recognition task, was associated with amplification of enhancement and suppression effects during stimulus encoding within visual association cortex. Our results indicate that enhancement and suppression are amplified for trials with the highest reward level relative to non-rewarded trials for a scene-selective cortical region. In a face-selective region, similar modulation of enhancement for the highest reward level relative to non-rewarded trials was found. Prefrontal cortex also showed enhanced activity during high reward trials. Overall these results reveal that reward motivation can play a pivotal role in driving performance through top-down signaling in frontal regions involved in WM, as well as visual association regions selective to processing the perceptual inputs of the items to be remembered.

Strategy-based reasoning training modulates cortical thickness and resting-state functional connectivity in adults with chronic traumatic brain injury.

INTRODUCTION: Prior studies have demonstrated training-induced changes in the healthy adult brain. Yet, it remains unclear how the injured brain responds to cognitive training months-to-years after injury. METHODS: Sixty individuals with chronic traumatic brain injury (TBI) were randomized into either strategy-based (N = 31) or knowledge-based (N = 29) training for 8 weeks. We measured cortical thickness and resting-state functional connectivity (rsFC) before training, immediately posttraining, and 3 months posttraining. RESULTS: Relative to the knowledge-based training group, the cortical thickness of the strategy-based training group showed diverse temporal patterns of changes over multiple brain regions (pvertex < .05, pcluster < .05): (1) increases followed by decreases, (2) monotonic increases, and (3) monotonic decreases. However, network-based statistics (NBS) analysis of rsFC among these regions revealed that the strategy-based training group induced only monotonic increases in connectivity, relative to the knowledge-based training group (|Z| > 1.96, pNBS < 0.05). Complementing the rsFC results, the strategy-based training group yielded monotonic improvement in scores for the trail-making test (p < .05). Analyses of brain-behavior relationships revealed that improvement in trail-making scores were associated with training-induced changes in cortical thickness (pvertex < .05, pcluster < .05) and rsFC (pvertex < .05, pcluster < .005) within the strategy-based training group. CONCLUSIONS: These findings suggest that training-induced brain plasticity continues through chronic phases of TBI and that brain connectivity and cortical thickness may serve as markers of plasticity.