Verbal retrieval deficits due to traumatic brain injury are associated with changes in event related potentials during a Go-NoGo task.

OBJECTIVE: Verbal retrieval (VR) deficits often occur after traumatic brain injury (TBI), but the mechanisms remain unclear. We examined how event-related potentials (ERPs) during a Go-NoGo task were associated with VR deficits. METHODS: Sixty veterans with a history of TBI underwent a neuropsychological battery and a Go-NoGo task with concurrent EEG recording. We compared task performance and ERP measures (N2, P3) between those with and those without persistent injury-related VR deficits. We then used generalized linear modeling to examine the relationship between ERP measures and scores on measures of executive function and processing speed. RESULTS: Go-NoGo task performance was comparable between the groups. Those with VR deficits had larger N2 amplitude in NoGo than in Go conditions. In participants with VR deficits, larger NoGo N2/P3 amplitude predicted faster processing speed. Furthermore, larger P3 amplitude and shorter P3 latency of the difference wave (NoGo - Go) predicted faster processing speed in those with VR deficits. CONCLUSIONS: Despite no difference in Go-NoGo task performance, ERP amplitude and latency measures associated with cognitive control during Go-NoGo distinguished TBI individuals with VR deficits from those without. SIGNIFICANCE: This study furthers our understanding of VR deficits in TBI and implicates potential application of ERP measures in monitoring and treating such deficits.

A modified neural circuit framework for semantic memory retrieval with implications for circuit modulation to treat verbal retrieval deficits.

Word finding difficulty is a frequent complaint in older age and disease states, but treatment options are lacking for such verbal retrieval deficits. Better understanding of the neurophysiological and neuroanatomical basis of verbal retrieval function may inform effective interventions. In this article, we review the current evidence of a neural retrieval circuit central to verbal production, including words and semantic memory, that involves the pre-supplementary motor area (pre-SMA), striatum (particularly caudate nucleus), and thalamus. We aim to offer a modified neural circuit framework expanded upon a memory retrieval model proposed in 2013 by Hart et al., as evidence from electrophysiological, functional brain imaging, and noninvasive electrical brain stimulation studies have provided additional pieces of information that converge on a shared neural circuit for retrieval of memory and words. We propose that both the left inferior frontal gyrus and fronto-polar regions should be included in the expanded circuit. All these regions have their respective functional roles during verbal retrieval, such as selection and inhibition during search, initiation and termination of search, maintenance of co-activation across cortical regions, as well as final activation of the retrieved information. We will also highlight the structural connectivity from and to the pre-SMA (e.g., frontal aslant tract and fronto-striatal tract) that facilitates communication between the regions within this circuit. Finally, we will discuss how this circuit and its correlated activity may be affected by disease states and how this circuit may serve as a novel target engagement for neuromodulatory treatment of verbal retrieval deficits.

Analyzing direct effects of education level and estimated IQ between cognitively intact Mexican Americans and Non-Hispanic whites on a confrontational naming task.

Confrontational naming is widely used in diagnosing neurodegenerative disorders like MCI and dementia, and previous research indicates that healthy Non-Hispanic Whites outperform Hispanics in such tasks. However, understanding the factors contributing to score differences among ethnic groups remains limited. This study focuses on cognitively intact Mexican Americans and Non-Hispanic White older adults from the TARCC Hispanic Cohort project. Hierarchical regression analyses reveal that sex, age, ethnicity, education level, and estimated IQ significantly predict performance on the Boston Naming Test (BNT). Notably, education level and estimated IQ more strongly influence BNT performance in Mexican Americans than in Non-Hispanic Whites. When controlling for education level, estimated IQ has a more pronounced impact on BNT performance in aging Mexican Americans compared to Non-Hispanic Whites. Conversely, after controlling for estimated IQ, the influence of education level is weaker for Mexican Americans than Non-Hispanic Whites. These findings emphasize the need for careful evaluation of confrontational naming task scores in diverse ethnic groups, emphasizing the critical role of education and estimated IQ in understanding performance disparities.

P3a amplitude to trauma-related stimuli reduced after successful trauma-focused PTSD treatment.

An elevated P3a amplitude to trauma-related stimuli is strongly associated with posttraumatic stress disorder (PTSD), yet little is known about whether this response to trauma-related stimuli is affected by treatment that decreases PTSD symptoms. As an analysis of secondary outcome measures from a randomized controlled trial, we investigated the latency and amplitude changes of the P3a in responses in a three-condition oddball visual task that included trauma-related (combat scenes) and trauma-unrelated (threatening animals) distractors. Fifty-five U.S. veterans diagnosed with combat-related PTSD were randomized to receive either active or sham repetitive transcranial magnetic stimulation (rTMS). All received cognitive processing therapy, CPT+A, which requires a written account of the index trauma. They were tested before and 6 months after protocol completion. P3a amplitude and response time decreases were driven largely by the changes in the responses to the trauma-related stimuli, and this decrease correlated to the decrease in PTSD symptoms. The amplitude changes were greater in those who received rTMS + CPT than in those who received sham rTMS + CPT, suggesting that rTMS plays beneficial role in reducing arousal and threat bias, which may allow for more effective engagement in trauma-focused PTSD treatment.

Neurocognitive outcomes of older National Football League retirees.

OBJECTIVE: Determine if head-injury exposure relates to later-in-life cognitive decline in older National Football League (NFL) retirees. METHOD: NFL retirees (aged 50+) with or without cognitive impairment underwent baseline (n = 53) and follow-up (n = 29; 13-59 months later) neuropsychological evaluations. Cognitively normal (CN) retirees (n = 26) were age- and education-matched to healthy controls (n = 26). Cognitively impaired (CI) retirees with mild cognitive impairment or dementia (n = 27) were matched to a clinical sample (CS) by age, sex, education, and diagnosis (n = 83). ANOVAs compared neuropsychological composites at baseline and over time between retirees and their matched groups. Regression models evaluated whether concussions, concussions with loss of consciousness (LOC), or games played predicted neuropsychological functioning. RESULTS: At baseline, CN retirees had slightly worse memory than controls (MCN retirees = 50.69, SECN retirees = 1.320; MHealthy controls = 57.08, SEHealthy controls = 1.345; p = 0.005). No other group diferences were observed, and head-injury exposure did not predict neurocognitive performance at baseline or over time. CONCLUSIONS: Head-injury exposure was not associated with later-in-life cognition, regardless of cognitive diagnosis. Some retirees may exhibit lower memory scores compared to age-matched peers, though this is of unclear clinical significance.

High-definition transcranial direct current stimulation modulates theta response during a Go-NoGo task in traumatic brain injury.

OBJECTIVE: High Definition transcranial Direct Current Stimulation (HD-tDCS) has been shown to improve cognitive performance in individuals with chronic traumatic brain injury (TBI), although electrophysiological mechanisms remain unclear. METHODS: Veterans with TBI underwent active anodal (N = 15) vs sham (N = 10) HD-tDCS targeting the pre-supplementary motor area (pre-SMA). A Go-NoGo task was conducted simultaneously with electroencephalography (EEG) at baseline and after intervention completion. RESULTS: We found increased theta event-related spectral perturbation (ERSP) and inter-trial phase coherence (ITPC) during Go in the frontal midline electrodes overlying the pre-SMA after active HD-tDCS intervention, but not after sham. We also found increased theta phase coherence during Go between the frontal midline and left posterior regions after active HD-tDCS. A late increase in alpha-theta ERSP was found in the left central region after active HD-tDCS. Notably, lower baseline theta ERSP/ITPC in the frontal midline region predicted more post-intervention improvement in Go performance only in the active group. CONCLUSIONS: There are local and interregional oscillatory changes in response to HD-tDCS modulation in chronic TBI. SIGNIFICANCE: These findings may guide future research in utilizing EEG time-frequency metrics not only to measure interventional effects, but also in selecting candidates who may optimally respond to treatment.

Auditory N2 Correlates of Treatment Response in Posttraumatic Stress Disorder.

Emotional processing and cognitive control are implicated as being dysfunctional in posttraumatic stress disorder (PTSD) and targeted in cognitive processing therapy (CPT), a trauma-focused treatment for PTSD. The N2 event-related potential has been interpreted in the context of emotional processing and cognitive control. In this analysis of secondary outcome measures from a randomized controlled trial, we investigated the latency and amplitude changes of the N2 in responses to task-relevant target tones and task-irrelevant distractor sounds (e.g., a trauma-related gunshot and a trauma-unrelated lion's roar) and the associations between these responses and PTSD symptom changes. United States military veterans (N = 60) diagnosed with combat-related PTSD were randomized to either active or sham repetitive transcranial magnetic stimulation (rTMS) and received a CPT intervention that included a written trauma account element (CPT+A). Participants were tested before and 6 months after protocol completion. Reduction in N2 amplitude to the gunshot stimulus was correlated with reductions in reexperiencing, |r| = .445, and hyperarousal measures, |r| = .364. In addition, in both groups, the latency of the N2 event-related potential to the distractors became longer with treatment and the N2 latency to the task-relevant stimulus became shorter, ηp 2  = .064, both of which are consistent with improved cognitive control. There were no between-group differences in N2 amplitude and latency. Normalized N2 latencies, reduced N2 amplitude to threatening distractors, and the correlation between N2 amplitude reduction and PTSD symptom reduction reflect improved cognitive control, consistent with the CPT+A objective of addressing patients' abilities to respond more appropriately to trauma triggers.

Baseline delayed verbal recall predicts response to high definition transcranial direct current stimulation targeting the superior medial frontal cortex.

Anodal high definition transcranial direct current stimulation (HD-tDCS) targeting the pre-supplementary motor area/dorsal anterior cingulate cortex (pre-SMA/dACC) has recently been shown to improve verbal retrieval deficits in veterans with chronic traumatic brain injury (TBI) (Motes et al., 2020), but predictors of treatment response are unclear. We hypothesized that baseline delayed verbal recall, a sensitive measure for post-TBI chronic cognitive decline, would predict therapeutic effects of HD-tDCS targeting the pre-SMA/dACC for verbal retrieval deficits. Standardized verbal retrieval measures were administered at baseline, immediately after and 8 weeks after treatment completion. We applied mixed generalized linear modeling as a post-hoc subgroup analysis to the verbal retrieval scores that showed significant improvement in Motes at el. (2020) to examine effects of active stimulation across the groups with baseline-intact delayed recall (N = 10) and baseline-impaired delayed recall (N = 8), compared to sham (N = 7). Individuals with impaired baseline delayed recall showed significant improvement (compared to baseline) in both category fluency and color-word inhibition/switch, while individuals with intact delayed recall showed significant improvement only in color-word inhibition/switch. Baseline delayed verbal recall may therefore be considered as a predictor for future electromodulation studies targeting frontal structures to treat TBI-related verbal deficits.

Identification of selection and inhibition components in a Go/NoGo task from EEG spectra using a machine learning classifier.

INTRODUCTION: Prior Go/NoGo studies have localized specific regions and EEG spectra for which traditional approaches have distinguished between Go and NoGo conditions. A more detailed characterization of the spatial distribution and timing of the synchronization of frequency bands would contribute substantially to the clarification of neural mechanisms that underlie performance of the Go/NoGo task. METHODS: The present study used a machine learning approach to learn the features that distinguish between ERSPs involved in selection and inhibition in a Go/NoGo task. A single-layer neural network classifier was used to predict task conditions for each subject to characterize ERSPs associated with Go versus NoGo trials. RESULTS: The final classifier accurately identified individual task conditions at an overall rate of 92%, estimated by fivefold cross-validation. The detailed accounting of EEG time-frequency patterns localized to brain regions (i.e., thalamus, pre-SMA, orbitofrontal cortex, and superior parietal cortex) corroborates and also elaborates upon previous findings from fMRI and EEG studies, and expands the information about EEG power changes in multiple frequency bands (i.e., primarily theta power increase, alpha decreases, and beta increases and decreases) within these regions underlying the selection and inhibition processes engaged in the Go and NoGo trials. CONCLUSION: This time-frequency-based classifier extends previous spatiotemporal findings and provides information about neural mechanisms underlying selection and inhibition processes engaged in Go and NoGo trials, respectively. This neural network classifier can be used to assess time-frequency patterns from an individual subject and thus may offer insight into therapeutic uses of neuromodulation in neural dysfunction.

High-Definition Transcranial Direct Current Stimulation to Improve Verbal Retrieval Deficits in Chronic Traumatic Brain Injury.

Chronic verbal retrieval deficits have been noted in traumatic brain injury (TBI), but no U.S. Food and Drug Administration-approved interventions are available. The present study investigated whether 10 sessions of 20 min of 1 mA anodal high-definition transcranial direct current stimulation (HD-tDCS) targeting pre-supplementary motor area/dorsal anterior cingulate cortex (preSMA/dACC) compared with sham HD-tDCS would improve verbal retrieval deficits in TBI patients. Improvements in verbal retrieval processes were observed up to 8 weeks post-treatment. Thus, potential dysfunction to verbal retrieval circuitry in TBI appears amenable to remediation through electromodulation with HD tDCS to the preSMA/dACC. Although further studies clarifying mechanisms by which tDCS brought about these improvements will likely inform refinements in the application of this therapeutic technique, the findings suggest the efficacy of using HD-tDCS to target other systems vulnerable to TBI to improve functioning.

Neurophysiology of threat processing bias in combat-related post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is a debilitating condition that may develop after experiencing a traumatic event. Combat exposure increases an individual's chance of developing PTSD, making veterans especially susceptible to the disorder. PTSD is characterized by dysregulated emotional networks, memory deficits, and a hyperattentive response to perceived threatening stimuli. Recently, there have been a number of imaging studies that show structural and functional abnormalities associated with PTSD; however, there have been few studies utilizing electroencephalography (EEG). The goal of this study was to characterize **EEG brain dynamics in individuals with PTSD, in order to better understand the neurophysiological underpinnings of some of the salient features of PTSD, such as threat-processing bias. Veterans of Operation Enduring Freedom/Iraqi Freedom completed an implicit visual threat semantic memory recognition task with stimuli that varied on both category (animals, items, nature, and people) and feature (threatening and nonthreatening) membership, including trauma-related stimuli. Combat veterans with PTSD had slower reaction times for the threatening stimuli relative to the combat veterans without PTSD (VETC). There were trauma-specific effects in frontal regions, with theta band EEG power reductions for the threatening combat scenes in the PTSD patients compared to the VETC group. Additionally, a moderate negative correlation was observed between trauma-specific frontal theta power and hyperarousal symptoms as measured by clinically administered PTSD scale. These findings complement and extend current models of cortico-limbic dysfunction in PTSD. The moderate negative correlation between frontal theta power and hyperarousal endorsements suggests the utility of these measures as therapeutic markers of symptomatology in PTSD patients.

A Pilot Study of Changes in Medial Temporal Lobe Fractional Amplitude of Low Frequency Fluctuations after Sildenafil Administration in Patients with Alzheimer's Disease.

Alzheimer's disease (AD) is the most common cause of neurodegenerative cognitive impairment, defined by abnormal accumulations of amyloid-ß and tau. Approaches directly targeting these proteins have not resulted in a disease modifying therapy. Neurovascular unit dysfunction is a feature of AD offering an alternative target for intervention. Sildenafil, a phosphodiesterase 5 (PDE5) inhibitor, improves cognitive functioning in mouse models of AD. Recent work in AD patients has demonstrated increased cerebral blood flow, as well as brain oxygen utilization after a single dose of sildenafil. Its effect on nitric oxide-cGMP signaling may have downstream effects on neuroplasticity, amyloid-ß processing, and improved neurovascular unit function. Fractional amplitude of low frequency fluctuations (fALFF) assesses spontaneous neural activity via resting state fMRI BOLD signal (0.01-0.08 or 0.10 Hz). In AD, other assessments have revealed increased fALFF in hippocampi and parahippocampal gyri. Here, we examined the effects of a single dose of sildenafil on fALFF in a cohort of 10 AD patients. We found a decrease (p < 0.03, α= 0.05) in fALFF an hour after sildenafil administration in the right hippocampus. Additionally, cerebral vascular reactivity in response to carbon dioxide inhalation, a measure of neural vascular reserve previously collected on most of these participants, was not significantly correlated with this decrease, implying that change in fALFF may not have been solely due to altered vascular reactivity to CO2. We demonstrate that in patients with AD, hippocampal fALFF decreases in response to sildenafil, suggesting a normalization. These findings support further investigation into the effects of sildenafil in AD.

Conjoint differences in inhibitory control and processing speed in childhood to older adult cohorts: Discriminant functions from a Go/No-Go task.

To investigate differences in inhibitory control and processing speed over the life span, participants in 7- to 8-, 10- to 11-, 12- to 15-, 18- to 25-, and 54- to 80-year-old age cohorts completed a Go/No-Go task requiring varying levels of semantic categorization. Discriminant function analysis of correct rejection rates (CRRs), hit rates (HRs), and reaction times (RTs) revealed a function on which CRR loaded positively and RT loaded negatively, across categorization levels. Scores increased from youngest to the younger adult cohort and decreased for the older adult cohort. On a second function, CRR and RT loaded positively and HR loaded negatively across categorization levels. Scores were highest for the older adult cohort and higher for the youngest cohort than for the younger adult cohort. The results suggest change along 2 dimensions might underlie cognitive development: (a) combined increased inhibitory control and processing speed and (b) combined increased speed and decreased biased responding for better inhibitory control. In addition, 2 dimensions might underlie senescence: (a) combined decreased inhibitory control and processing speed and (b) combined decreased speed and increased biased responding for better inhibitory control. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Repetitive TMS to augment cognitive processing therapy in combat veterans of recent conflicts with PTSD: A randomized clinical trial.

BACKGROUND: The objective was to test whether repetitive Transcranial Magnetic Stimulation (rTMS) just prior to Cognitive Processing Therapy (CPT) would significantly improve the clinical outcome compared to sham rTMS prior to CPT in veterans with PTSD. METHODS: Veterans 18-60 years of age with current combat-related PTSD symptoms were randomized, using a 1:1 ratio in a parallel design, to active (rTMS+CPT) versus sham (sham+CPT) rTMS just prior to weekly CPT for 12-15 sessions. Blinded raters evaluated veterans at baseline, after the 5th and 9th treatments, and at 1, 3, and 6 months post-treatment. Clinician Administered PTSD Scale (CAPS) was the primary outcome measure with the PTSD Checklist (PCL) as a secondary outcome measure. The TMS coil (active or sham) was positioned over the right dorsolateral prefrontal cortex (110% MT, 1Hz continuously for 30min, 1800 pulses/treatment). RESULTS: Of the 515 individuals screened for the study, 103 participants were randomized to either active (n = 54) or sham rTMS (n = 49). Sixty-two participants (60%) completed treatment and 59 (57%) completed the 6-month assessment. The rTMS+CPT group showed greater symptom reductions from baseline on both CAPS and PCL across CPT sessions and follow-up assessments, t(df ≥ 325) ≤ -2.01, p ≤ 0.023, one-tailed and t(df ≥ 303) ≤ -2.14, p ≤ 0.017, one-tailed, respectively. LIMITATIONS: Participants were predominantly male and limited to one era of conflicts as well as those who could safely undergo rTMS. CONCLUSIONS: The addition of rTMS to CPT compared to sham with CPT produced significantly greater PTSD symptom reduction early in treatment and was sustained up to six months post-treatment.

Higher-order cognitive training effects on processing speed-related neural activity: a randomized trial.

Higher-order cognitive training has shown to enhance performance in older adults, but the neural mechanisms underlying performance enhancement have yet to be fully disambiguated. This randomized trial examined changes in processing speed and processing speed-related neural activity in older participants (57-71 years of age) who underwent cognitive training (CT, N = 12) compared with wait-listed (WLC, N = 15) or exercise-training active (AC, N = 14) controls. The cognitive training taught cognitive control functions of strategic attention, integrative reasoning, and innovation over 12 weeks. All 3 groups worked through a functional magnetic resonance imaging processing speed task during 3 sessions (baseline, mid-training, and post-training). Although all groups showed faster reaction times (RTs) across sessions, the CT group showed a significant increase, and the WLC and AC groups showed significant decreases across sessions in the association between RT and BOLD signal change within the left prefrontal cortex (PFC). Thus, cognitive training led to a change in processing speed-related neural activity where faster processing speed was associated with reduced PFC activation, fitting previously identified neural efficiency profiles.

Trial-Level Regressor Modulation for Functional Magnetic Resonance Imaging Designs Requiring Strict Periodicity of Stimulus Presentations: Illustrated Using a Go/No-Go Task.

Computer-based assessment of many cognitive processes (eg, anticipatory and response readiness processes) requires the use of invariant stimulus display times (SDT) and intertrial intervals (ITI). Although designs with invariant SDTs and ITIs have been used in functional magnetic resonance imaging (fMRI) research, such designs are problematic for fMRI studies because of collinearity issues. This study examined regressor modulation with trial-level reaction times (RT) as a method for improving signal detection in a go/no-go task with invariant SDTs and ITIs. The effects of modulating the go regressor were evaluated with respect to the detection of BOLD signal-change for the no-go condition. BOLD signal-change to no-go stimuli was examined when the go regressor was based on a (a) canonical hemodynamic response function (HRF), (b) RT-based amplitude-modulated (AM) HRF, and (c) RT-based amplitude and duration modulated (A&DM) HRF. Reaction time-based modulation reduced the collinearity between the go and no-go regressors, with A&DM producing the greatest reductions in correlations between the regressors, and greater reductions in the correlations between regressors were associated with longer mean RTs and greater RT variability. Reaction time-based modulation increased statistical power for detecting group-level no-go BOLD signal-change across a broad set of brain regions. The findings show the efficacy of using regressor modulation to increase power in detecting BOLD signal-change in fMRI studies in which circumstances dictate the use of temporally invariant stimulus presentations.

Cognitive Slowing in Gulf War Illness Predicts Executive Network Hyperconnectivity: Study in a Population-Representative Sample.

Cognitive slowing is a prevalent symptom observed in Gulf War Illness (GWI). The present study assessed the extent to which functional connectivity between dorsolateral prefrontal cortex (DLPFC) and other task-relevant brain regions was predictive of GWI-related cognitive slowing. GWI patients (n = 54) and healthy veteran controls (n = 29) were assessed on performance of a processing speed task (the Digit Symbol Substitution Task; DSST) while undergoing functional magnetic resonance imaging (fMRI). GWI patients were slower on the DSST relative to controls. Bilateral DLPFC connectivity with task-relevant nodes was altered in GWI patients compared to healthy controls during DSST performance. Moreover, hyperconnectivity in these networks predicted GWI-related increases in reaction time on the DSST, whereas hypoconnectivity did not. These results suggest that GWI-related cognitive slowing reflects reduced efficiency in cortical networks.

Common and differential electrophysiological mechanisms underlying semantic object memory retrieval probed by features presented in different stimulus types.

How the brain combines the neural representations of features that comprise an object in order to activate a coherent object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular object. Sixteen subjects completed one of the three versions (N=48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1-4Hz, theta: 4-7Hz; alpha: 8-12Hz; beta: 13-19Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of semantic object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during semantic object memory retrieval.

Enhancing inferential abilities in adolescence: new hope for students in poverty.

The ability to extrapolate essential gist through the analysis and synthesis of information, prediction of potential outcomes, abstraction of ideas, and integration of relationships with world knowledge is critical for higher-order learning. The present study investigated the efficacy of cognitive training to elicit improvements in gist reasoning and fact recall ability in 556 public middle school students (grades seven and eight), vs. a sample of 357 middle school students who served as a comparison group, to determine if changes in gist reasoning and fact recall were demonstrated without cognitive training. The results showed that, in general, cognitive training increased gist reasoning and fact recall abilities in students from families in poverty as well as students from families living above poverty. However, the magnitude of gains in gist reasoning varied as a function of gender and grade level. Our primary findings were that seventh and eighth grade girls and eighth grade boys showed significant increases in gist reasoning after training regardless of socioeconomic status (SES). There were no significant increases in gist reasoning or fact recall ability for the 357 middle school students who served as a comparison group. We postulate that cognitive training in middle school is efficacious for improving gist reasoning ability and fact recall in students from all socioeconomic levels.

Investigating the neural bases for intra-subject cognitive efficiency changes using functional magnetic resonance imaging.

Several fMRI studies have examined brain regions mediating inter-subject variability in cognitive efficiency, but none have examined regions mediating intra-subject variability in efficiency. Thus, the present study was designed to identify brain regions involved in intra-subject variability in cognitive efficiency via participant-level correlations between trial-level reaction time (RT) and trial-level fMRI BOLD percent signal change on a processing speed task. On each trial, participants indicated whether a digit-symbol probe-pair was present or absent in an array of nine digit-symbol probe-pairs while fMRI data were collected. Deconvolution analyses, using RT time-series models (derived from the proportional scaling of an event-related hemodynamic response function model by trial-level RT), were used to evaluate relationships between trial-level RTs and BOLD percent signal change. Although task-related patterns of activation and deactivation were observed in regions including bilateral occipital, bilateral parietal, portions of the medial wall such as the precuneus, default mode network regions including anterior cingulate, posterior cingulate, bilateral temporal, right cerebellum, and right cuneus, RT-BOLD correlations were observed in a more circumscribed set of regions. Positive RT-BOLD correlations, where fast RTs were associated with lower BOLD percent signal change, were observed in regions including bilateral occipital, bilateral parietal, and the precuneus. RT-BOLD correlations were not observed in the default mode network indicating a smaller set of regions associated with intra-subject variability in cognitive efficiency. The results are discussed in terms of a distributed area of regions that mediate variability in the cognitive efficiency that might underlie processing speed differences between individuals.