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1.  Affective differences in Iowa Gambling Task performance associated with sexual risk taking and substance use among HIV-positive and HIV-negative men who have sex with men 
We investigated the relationship between emotional distress and decision-making in sexual risk and substance use behavior among 174 (ages 25 to 50, 53% black) men who have sex with men (MSM), a population at increased risk for HIV. The sample was stratified by HIV status. Measures of affective decision-making (Iowa Gambling Task, IGT, Bechara et al., 1994), depression, anxiety, sex acts, and substance use during the past 60 days were collected at our research center. Negative binomial regression models were used to examine the relationship between age, HIV status, anxiety, depression, and IGT performance in the prediction of number of risky sex acts and substance use days. Among those without anxiety or depression, both number of risky sex acts and drug use days decreased with better performance during risky trials (i.e., last two blocks) of the IGT. For those with higher rates of anxiety, but not depression, IGT risk trial performance and risky sex acts increased concomitantly. Anxiety also interacted with IGT performance across all trials to predict substance use, such that anxiety was associated with greater substance use among those with better IGT performance. The opposite was true for those with depression, but only during risk trials. HIV-positive participants reported fewer substance use days than HIV-negative participants, but there was no difference in association between behavior and IGT performance by HIV status. Our findings suggest that anxiety may exacerbate risk-taking behavior when affective decision-making ability is intact. The relationship between affective decision-making and risk taking may be sensitive to different profiles of emotional distress, as well as behavioral context. Investigations of affective decision-making in sexual risk taking and substance use should examine different distress profiles separately, with implications for HIV prevention efforts.
PMCID: PMC4849548  PMID: 26745769
Decision-Making; Iowa Gambling Task; Anxiety; Sexual Risk Taking; Substance Use
2.  An Item Response Theory Analysis of the Executive Interview and Development of the EXIT8: A Project FRONTIER Study 
The EXIT25 is an effective measure of executive dysfunction, but may be inefficient due to the time it takes to complete 25 interview-based items. The current study aimed to examine psychometric properties of the EXIT25, with a specific focus on determining if a briefer version of the measure could comprehensively assess executive dysfunction.
The current study applied a graded response model (a type of item response theory model for polytomous categorical data) to identify items that were most closely related to the underlying construct of executive functioning and best discriminated between varying levels of executive functioning. Participants were 660 adults ages 40 to 96 living in West Texas, who were recruited through an ongoing epidemiological study of rural health and aging, called Project FRONTIER. The EXIT25 was the primary measure examined. Participants also completed the Trail Making Test and Controlled Oral Word Association Test, among other measures, to examine the convergent validity of a brief form of the EXIT25.
Eight items were identified that provided the majority of the information about the underlying construct of executive functioning; total scores on these items were associated with total scores on other measures of executive functioning and were able to differentiate between cognitively healthy, mildly cognitively impaired, and demented participants. In addition, cutoff scores were recommended based on sensitivity and specificity of scores.
A brief, eight-item version of the EXIT25 may be an effective and efficient screening for executive dysfunction among older adults.
PMCID: PMC4441831  PMID: 25748691
Item response theory; Executive functioning; Aging; Brief assessment; Cognition
3.  The Moderating Effects of Cannabis Use and Decision Making on the Relationship between Conduct Disorder and Risky Sexual Behavior 
Risky sexual behavior (RSB) is a current public health concern affecting adolescents and young adults. Conduct disorder, cannabis use and decision making (DM) ability are interrelated constructs that are relevant to RSB; however, there is little research on the association of DM and RSB. Participants were 79 cannabis users assessed through self-report measures of RSB and mental health, and a timeline follow-back procedure for substance use. DM ability was assessed via the Iowa Gambling Task. We found that more conduct disorder symptoms accounted for unique variance in measures of overall RSB and an earlier initiation of oral sex, even when taking into account DM and cannabis use. Amount of cannabis use and DM ability moderated the relationships between number of conduct disorder symptoms and number of oral sex partners and age of initiation for vaginal sex. An increase in conduct disorder symptoms was associated with more oral sex partners when DM was poor and fewer partners when DM was better, however this relationship was only present at higher levels of cannabis use. Furthermore, when DM was poor, more conduct disorder symptoms predicted a younger age of initiation of vaginal sex, with the age decreasing as amount of cannabis use increased. Determining how DM influences RSB may assist in the identification of novel treatment approaches to reduce engagement in RSB.
PMCID: PMC4441872  PMID: 25832553
risky sexual behavior; conduct disorder; decision making; cannabis
4.  Neuropsychological Test Selection for Cognitive Impairment Classification: A Machine Learning Approach 
Reducing the amount of testing required to accurately detect cognitive impairment is clinically relevant. The aim of this research was to determine the fewest number of clinical measures required to accurately classify participants as healthy older adult, mild cognitive impairment (MCI) or dementia using a suite of classification techniques.
Two variable selection machine learning models (i.e., naive Bayes, decision tree), a logistic regression, and two participant datasets (i.e., clinical diagnosis, clinical dementia rating; CDR) were explored. Participants classified using clinical diagnosis criteria included 52 individuals with dementia, 97 with MCI, and 161 cognitively healthy older adults. Participants classified using CDR included 154 individuals CDR = 0, 93 individuals with CDR = 0.5, and 25 individuals with CDR = 1.0+. Twenty-seven demographic, psychological, and neuropsychological variables were available for variable selection.
No significant difference was observed between naive Bayes, decision tree, and logistic regression models for classification of both clinical diagnosis and CDR datasets. Participant classification (70.0 – 99.1%), geometric mean (60.9 – 98.1%), sensitivity (44.2 – 100%), and specificity (52.7 – 100%) were generally satisfactory. Unsurprisingly, the MCI/CDR = 0.5 participant group was the most challenging to classify. Through variable selection only 2 – 9 variables were required for classification and varied between datasets in a clinically meaningful way.
The current study results reveal that machine learning techniques can accurately classifying cognitive impairment and reduce the number of measures required for diagnosis.
PMCID: PMC4809360  PMID: 26332171
dementia; mild cognitive impairment; diagnosis; machine learning; naive Bayes
5.  Feasibility of event-related potential methodology to evaluate changes in cortical processing after rehabilitation in children with cerebral palsy: A pilot study 
This study examined the feasibility of using event-related potentials (ERPs) to measure changes in cortical processing following an established rehabilitative intervention (constraint-induced movement therapy, CIMT) for children with cerebral palsy (CP). Sixteen participants with a diagnosis of hemiparetic CP, with a median age of 6 years, were assessed pre and immediately post CIMT and at 6-month follow-up, using a picture–word match/mismatch discrimination task and standard neurobehavioral measures. Intervention effects were evident in improved performance on behavioral tests of sensory and motor function and the increased mean ERP amplitude of the N400 match/mismatch response on the side ipsilateral to the lesion. These effects were maintained 6 months after the intervention. No such changes were observed on the side contralateral to the lesion. This research suggests that ERPs can measure rehabilitation-induced changes in neural function in children with CP.
PMCID: PMC4800817  PMID: 24953907
Cerebral palsy; Rehabilitation; Event-related potentials; Pediatric; Constraint therapy
6.  Test–retest reliability and effects of repeated testing and satiety on performance of an Emotional Test Battery 
The P1vital® Oxford Emotional Test Battery (ETB) comprises five computerized tasks designed to assess cognition and emotional processing in human participants. It has been used in between-subjects experimental designs; however, it is unclear whether the battery can be used in crossover designs. This is of particular importance given the increasing use of ETB tasks for repeated assessment of depressed patients in clinical trials and clinical practice. In addition, although satiety state has been reported to affect performance on some cognitive and emotional tasks, it is not known whether it can influence performance on the ETB. Two studies explored these issues. In Experiment 1, 30 healthy women were tested on the ETB on 4 separate occasions (each a week apart) in a within-subjects design. In Experiment 2, another 30 healthy women were randomized to either a satiated or a hungry condition, where they were given an ad libitum lunch of cheese sandwiches, before (satiated) or after (hungry) they were asked to complete the ETB. Experiment 1 demonstrated good test–retest reliability for the ETB. One of the tasks was free from practice effects, whilst performance on the other four tasks stabilized after the first two sessions. In Experiment 2, eating to satiety only affected performance on a single ETB task. These results suggest that the ETB can be used in crossover designs after two initial training sessions. Further, as a robust satiety manipulation had only a limited effect on a single ETB task, it is unlikely that appetitive state will confound ETB performance.
PMCID: PMC4784484  PMID: 26702993
Emotional Test Battery; ETB; practice effects; satiety; crossover design
7.  Recovery of Visual Search following Moderate to Severe Traumatic Brain Injury 
Deficits in attentional abilities can significantly impact rehabilitation and recovery from traumatic brain injury (TBI). This study investigated the nature and recovery of pre-attentive (parallel) and attentive (serial) visual search abilities after TBI.
Participants were 40 individuals with moderate to severe TBI who were tested following emergence from post-traumatic amnesia and approximately 8-months post-injury, as well as 40 age and education matched controls. Pre-attentive (automatic) and attentive (controlled) visual search situations were created by manipulating the saliency of the target item amongst distractor items in visual displays. The relationship between pre-attentive and attentive visual search rates and follow-up community integration were also explored.
The results revealed intact parallel (automatic) processing skills in the TBI group both post-acutely and at follow-up. In contrast, when attentional demands on visual search were increased by reducing the saliency of the target, the TBI group demonstrated poorer performances compared to the control group both post-acutely and 8-months post-injury. Neither pre-attentive nor attentive visual search slope values correlated with follow-up community integration.
These results suggest that utilizing intact pre-attentive visual search skills during rehabilitation may help to reduce high mental workload situations, thereby improving the rehabilitation process. For example, making commonly used objects more salient in the environment should increase reliance or more automatic visual search processes and reduce visual search time for individuals with TBI.
PMCID: PMC4355332  PMID: 25671675
attention; closed head injury; outcome; pre-attentive processes; parallel and serial search
8.  Initial validation of a web-based self-administered neuropsychological test battery for older adults and seniors 
Introduction: Computerized neuropsychological tests are effective in assessing different cognitive domains, but are often limited by the need of proprietary hardware and technical staff. Web-based tests can be more accessible and flexible. We aimed to investigate validity, effects of computer familiarity, education, and age, and the feasibility of a new web-based self-administered neuropsychological test battery (Memoro) in older adults and seniors. Method: A total of 62 (37 female) participants (mean age 60.7 years) completed the Memoro web-based neuropsychological test battery and a traditional battery composed of similar tests intended to measure the same cognitive constructs. Participants were assessed on computer familiarity and how they experienced the two batteries. To properly test the factor structure of Memoro, an additional factor analysis in 218 individuals from the HUNT population was performed. Results: Comparing Memoro to traditional tests, we observed good concurrent validity (r = .49–.63). The performance on the traditional and Memoro test battery was consistent, but differences in raw scores were observed with higher scores on verbal memory and lower in spatial memory in Memoro. Factor analysis indicated two factors: verbal and spatial memory. There were no correlations between test performance and computer familiarity after adjustment for age or age and education. Subjects reported that they preferred web-based testing as it allowed them to set their own pace, and they did not feel scrutinized by an administrator. Conclusions: Memoro showed good concurrent validity compared to neuropsychological tests measuring similar cognitive constructs. Based on the current results, Memoro appears to be a tool that can be used to assess cognitive function in older and senior adults. Further work is necessary to ascertain its validity and reliability.
PMCID: PMC4732451  PMID: 26009791
Memory; Internet; Assessment; Computer; HUNT
9.  Posterior brain white matter abnormalities in older adults with probable mild cognitive impairment 
Much of the mild cognitive impairment (MCI) neuroimaging literature has exclusively focused on regions associated with Alzheimer’s disease. Little research has examined white matter abnormalities of other brain regions, including those associated with visual processing, despite evidence that other brain abnormalities appear in these regions in early disease stages.
Diffusion tensor imaging (DTI) was utilized to examine participants (n = 44) that completed baseline imaging as part of a longitudinal healthy aging study. Participants were divided into two groups based on scores from the Montreal Cognitive Assessment (MoCA), a brief screening tool for MCI. Participants who scored < 26 were defined as “probable MCI” while those who scored ≥ 26 were labled cognitively healthy. Two DTI indices were analyzed including fractional anisotropy (FA) and mean diffusivity (MD). DTI values for white matter in the lingual gyrus, cuneus, pericalcarine, fusiform gyrus and all four lobes were compared using MANOVA. Regression analyses examined the relationship between DTI indices and total MoCA score.
Results revealed significantly lower FA in the probable MCI group in the cuneus, fusiform, pericalcarine and occipital lobe, and significantly higher MD in the temporal lobe. Fusiform FA and temporal lobe MD were significantly related to total MoCA score after accounting for age and education.
Results indicate that there are posterior white matter microstructural changes in individuals with probable MCI. These differences demonstrate that white matter abnormalities are evident among individuals with probable MCI in regions beyond those commonly associated with Alzheimer’s disease and anterior brain aging patterns.
PMCID: PMC4355053  PMID: 25523313
10.  Mesial Temporal Lobe and Memory Function in Autism Spectrum Disorder: An Exploration of Volumetric Findings 
Studies have shown that individuals with autism spectrum disorder (ASD) tend to perform significantly below typical developing individuals on standardized measures of memory, even when not significantly different on measures of IQ. The current study sought to examine within ASD whether anatomical correlates of memory performance differed between those with average-to-above-average IQ (AIQ Group) compared to those with low average to borderline ability (LIQ group) as well as in relations to typically-developing comparisons (TDC). Using automated volumetric analyses, we examined regional volume of classic memory areas including the hippocampus, parahippocampal gyrus, entorhinal cortex, and amygdala in an all-male sample AIQ (n = 38) and LIQ (n = 18) individuals with ASD along with 30 typically-developing comparisons (TDC). Memory performance was assessed using the Test of Memory and Learning (TOMAL) compared among the groups and then correlated with regional brain volumes. Analyses revealed group differences on almost all facets of memory and learning as assessed by the various subtests of the TOMAL. The three groups did not differ on any ROI memory-related brain volumes. However, significant size-memory function interactions were observed. Negative correlations were found between the volume of the amygdala and composite, verbal, and delayed memory indices for the LIQ ASD group indicating larger volume related to poorer performance. Implications for general memory functioning and dysfunctional neural connectivity in ASD are discussed.
PMCID: PMC4444055  PMID: 25749302
memory; autism spectrum disorders; neurodevelopmental disorders; magnetic resonance imaging
11.  The Wide Range Achievement Test-4 Reading Subtest “Holds” in HIV-infected Individuals 
In order to detect HIV-associated neurocognitive decline, it is important to accurately estimate individuals’ premorbid levels of cognitive functioning. Although previous studies have operated under the assumption that word reading tests are valid and stable indicators of premorbid abilities in HIV infection, studies of other populations have found this is not always the case. Therefore, it is important to empirically examine the validity of word reading tests as estimates of premorbid functioning specifically within the HIV population.
The Wide Range Achievement Test-4 Reading subtest (WRAT-4 Reading) was administered along with comprehensive neurocognitive assessments to 150 HIV seropositive (HIV+) and 76 HIV seronegative (HIV-) age-, education-, and sex-matched participants at baseline; a subset of 48 HIV+ individuals completed a second study visit (M=14.4 months), in which the alternate version of the WRAT-4 was administered.
Although HIV+ individuals evidenced worse current neurocognitive functioning than HIV- participants, WRAT-4 Reading performance was comparable between groups. Longitudinally, HIV+ participants evidenced improved disease and neuropsychological functioning, yet WRAT-4 Reading demonstrated strong test-retest reliability, no practice effect, and did not differ between the initial and follow-up assessments. Test-retest differences in reading performance were minor and not associated with changes in neurocognitive performance or changes in HIV disease.
We found no evidence of WRAT-4 Reading performance decline in HIV infection, despite HIV+/HIV- group differences in neurocognitive functioning. Additionally, reading performances among HIV+ individuals demonstrated consistency across study visits. These results begin to support the validity of the WRAT-4 Reading subtest as an indicator of premorbid cognitive functioning in HIV+ individuals.
PMCID: PMC4241141  PMID: 25283135
Premorbid functioning; Infectious diseases; Word reading; Assessment; Psychometrics
12.  Pain is Associated with Prospective Memory Dysfunction in Multiple Sclerosis 
Prospective memory (PM) pertains to the execution of a future goal or behavior. Initial research implies that people with multiple sclerosis (MS) are apt to show impaired prospective memory for activities of daily living (Rendell, Jensen, & Henry, 2007; Rendell et al., 2012). Yet, PM impairment does not occur in all people with MS. Thus, some other variable besides disease status alone may contribute to PM dysfunction in people with MS. Chronic pain may be such a variable. Approximately 50-70% of people with MS experience significant pain, and such pain has been thought to diminish memory function (Moore, Keogh, and Eccleston, 2009). To investigate this possibility, 96 patients with MS and 29 healthy subjects were administered the Memory for Intentions Screening Test (MIST) (Raskin, Buckheit, & Sherrod, 2010), a well-validated measure of prospective memory, and the Medical Outcomes Study Pain Effects Scale (PES) (Fischer, Rudick, Cutter, & Reingold, 1999) to assess chronic pain. After controlling for demographic variables and disability severity, subjective pain accounted for significant variance in PM, particularly for time-based intentions over sustained delay periods. These data accord well with assertions that pain may degrade ability to remember new intentions, and suggests that pain is associated with PM dysfunction in people with MS.
PMCID: PMC4229443  PMID: 25338929
13.  Clinical Utility of the N-back Task in Functional Neuroimaging Studies of Working Memory 
N-back tasks are commonly used in functional neuroimaging studies to identify the neural mechanisms supporting working memory (WM). Despite widespread use, the clinical utility of these tasks is not well specified. This study compared N-back performance during functional magnetic resonance imaging (fMRI) with task data acquired outside of the scanner as a measure of reliability across environment. N-back task validity was examined in relation to performance and rater-based measures used clinically to assess working memory.
Forty-three healthy adults completed Verbal and Object N-back tasks during fMRI scanning and outside the scanner. Task difficulty was varied parametrically (0, 1, and 2-back conditions). Order of N-back task completion was stratified by modality (Verbal/Object) and environment. Participants completed the Digit Span [DS] and provided self-ratings using the Behavior Rating Inventory of Executive Function [BRIEF-WM]).
Mean Verbal and Object N-back accuracy was above 95% across load conditions; task difficulty was effectively manipulated across load conditions. Performance accuracy did not significantly differ by environment. N-back reaction time was slower during fMRI (F =6.52, p=.01, ηp2=.13); participants were faster when initially completing tasks outside the scanner (ηp2=.10–.15). Verbal 2-back accuracy was significantly related to DS performance (r = .36, p = .02). N-back performance was not related to BRIEF-WM.
Our results provide evidence for reliability of N-back accuracy during fMRI scanning; however, reliability of reaction time data is affected by order of task presentation. Data regarding construct validity are inconsistent and emphasize the need to consider clinical utility of behavioral measures in the design and interpretation of functional neuroimaging studies.
PMCID: PMC4229404  PMID: 25252868
Digit Span; N-back; BRIEF; working memory; validity; reliability
14.  Executive Function Late Effects in Survivors of Pediatric Brain Tumors and Acute Lymphoblastic Leukemia 
Survivors of pediatric brain tumors (BT) and acute lymphoblastic leukemia (ALL) are at risk for neurocognitive late effects related to executive function.
Survivors of BT (48) and ALL (50) completed neurocognitive assessment. Executive function was compared to estimated IQ and population norms by diagnostic group.
Both BT and ALL demonstrated relative executive function weaknesses. As a group, BT survivors demonstrated weaker executive functioning than expected for age. Those BT survivors with deficits exhibited a profile suggestive of global executive dysfunction, while affected ALL survivors tended to demonstrate specific rapid naming deficits.
Findings suggest that pediatric BT and ALL survivors may exhibit different profiles of executive function late effects, which may necessitate distinct intervention plans.
PMCID: PMC4229447  PMID: 25126830
pediatric; leukemia; brain tumor; executive function; late effects
15.  Utility of the N-back task in survivors of childhood acute lymphoblastic leukemia 
The N-back task is often used in functional brain imaging studies to activate working memory networks; however, limited information is available on its association to clinical outcomes in children or cancer survivors. One hundred thirty-seven survivors of ALL (mean [SD] current age = 14.3 [4.8] years; time since diagnosis = 7.6 [1.6] years) completed the N-back task and comprehensive neurocognitive testing, including standardized measures of attention, processing speed, and working memory. Results indicated females demonstrated significantly slower reaction times (0-back p=0.02; 1-back p=0.03) compared to males. Survivors < 15 years old at the time of testing demonstrated a significant decrease in accuracy as working memory load increased compared to survivors ≥ 15 years old (p<0.001). Performance on the N-back task was associated with nonverbal working memory (rs=0.56, p<0.001) in survivors ≥ 15 years of age. For younger survivors, N-Back performance was more strongly associated with attention skills. Results suggest the N-back assesses different cognitive constructs at younger compared to older childhood ages. These age differences should be considered in interpreting functional brain imaging results.
PMCID: PMC4355950  PMID: 25252969
childhood acute lymphoblastic leukemia; working memory; N-back
16.  Allowing Brief Delays in Responding Improves Event-Based Prospective Memory for Young Adults Living with HIV Disease 
Event-based prospective memory (PM) tasks require individuals to remember to perform an action when they encounter a specific cue in the environment, and have clear relevance for daily functioning for individuals with HIV. In many everyday tasks, the individual must not only maintain the intent to perform the PM task, but the PM task response also competes with the alternative and more habitual task response. The current study examined whether event-based PM can be improved by slowing down the pace of the task environment. Fifty-seven young adults living with HIV performed an ongoing lexical decision task while simultaneously performing a PM task of monitoring for a specific word (which was focal to the ongoing task of making lexical decisions) or syllable contained in a word (which was nonfocal). Participants were instructed to refrain from making task responses until after a tone was presented, which occurred at varying onsets (0–1600ms) after each stimulus appeared. Improvements in focal and non-focal PM accuracy were observed with response delays of 600ms. Furthermore, the difference in PM accuracy between the low demand focal PM task and the resource demanding non-focal PM task was reduced by half across increasingly longer delays, falling from 31% at 0ms delay to only 14% at 1600ms delay. The degree of ongoing task response slowing for the PM conditions, relative to a control condition that did not have a PM task and made lexical decisions only, also decreased with increased delay. Overall, the evidence indicates that delaying the task responses of younger HIV-infected adults increased the probability that the PM relevant features of task stimuli were adequately assessed prior to the ongoing task response, and by implication that younger HIV infected adults can more adequately achieve PM goals when the pace of the task environment is slowed down.
PMCID: PMC4205178  PMID: 25116075
HIV/AIDS; Prospective memory; Executive functions; Response delay; Cue focality
17.  Effects of Information Processing Speed on Learning, Memory, and Executive Functioning in People Living With HIV/AIDS 
It is unclear whether or to what degree literacy, aging, and other neurologic abnormalities relate to cognitive deficits among people living with HIV/AIDS in the combined antiretroviral therapy (CART) era. The primary aim of this study was to simultaneously examine the association of age, HIV-associated motor abnormalities, major depressive disorder, and reading level with information processing speed, learning, memory, and executive functions, and to determine if processing speed mediated any of the relationships between cognitive and non-cognitive variables.
Participants were 186 racially and ethnically diverse men and women living with HIV/AIDS who underwent comprehensive neurological, neuropsychological, and medical evaluations. Structural equation modeling was utilized to assess the extent to which information processing speed mediated the relationship between age, motor abnormalities, major depressive disorder, and reading level with other cognitive abilities.
Age, motor dysfunction, reading level, and current major depressive disorder were all significantly associated with information processing speed. Information processing speed fully mediated the effects of age on learning, memory, and executive functioning, and partially mediated the effect of major depressive disorder on learning and memory. The effect of motor dysfunction on learning and memory was fully mediated by processing speed.
These findings provide support for information processing speed as a primary deficit which may account, at least in part, for many of the other cognitive abnormalities recognized in complex HIV/AIDS populations. The association of age and information processing speed may account for HIV/aging synergies in the generation of CART-era cognitive abnormalities.
PMCID: PMC4338860  PMID: 25111120
information processing speed; memory; executive function; structural equation model; human immunodeficiency virus
18.  Impact of fMRI Scanner Noise on Affective State and Attentional Performance 
Previous research has shown that performance on cognitive tasks administered in the scanner can be altered by the scanner environment. There are no previous studies that have investigated the impact of scanner noise using a well-validated measure of affective change. The goal of this study was to determine whether performance on an affective attentional task or emotional response to the task would change in the presence of distracting acoustic noise, such as that encountered in an MRI environment.
Thirty-four young adults with no self-reported history of neurologic disorder or mental illness completed three blocks of the affective Posner task outside of the scanner. The task was meant to induce frustration through monetary contingencies and rigged feedback.
Participants completed a self-assessment manikin at the end of each block to rate their mood, arousal level, and sense of dominance. During the task, half of the participants heard noise (recorded from a 4T MRI system), and half heard no noise.
The affective Posner task led to significant reductions in mood and increases in arousal in healthy participants. The presence of scanner noise did not impact task performance; however, individuals in the noise group did report significantly poorer mood throughout the task.
The results of the present study suggest that the acoustic qualities of MRI enhance frustration effects on an affective attentional task and that scanner noise may influence mood during similar fMRI tasks.
PMCID: PMC4501887  PMID: 26059389
Attention; affect; imaging; fMRI; noise
19.  An Examination of Executive Dysfunction Associated with Frontostriatal Circuitry in Parkinson’s Disease 
Parkinson’s disease (PD) is a neurodegenerative movement disorder presenting with subcortical pathology and characterized by motor deficits. However, as is frequently reported in the literature, patients with PD can also exhibit cognitive and behavioral (i.e., nonmotor) impairments, cognitive executive deficits and depression being the most prominent. Considerable attention has addressed the role that disruption to frontostriatal circuitry can play in mediating nonmotor dysfunction in PD. The three nonmotor frontostriatal circuits, which connect frontal cortical regions to the basal ganglia, originate from the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), and orbitofrontal cortex (OFC). The objective of the current study was to use our understanding of frontostriatal circuit function (via literature review) to categorize neuropsychological measures of cognitive and behavioral executive functions by circuit. To our knowledge, such an approach has not been previously attempted in the study of executive dysfunction in PD. Neuropsychological measures of executive functions and self-report behavioral inventories, categorized by circuit function, were administered to 32 nondemented patients with Parkinson’s disease (NDPD) and to 29 demographically matched, healthy normal control participants (NC). Our findings revealed significant group differences for each circuit, with the PD group performing worse than the NC group. Among the patients with PD, indices of impairment were greater for tasks associated with DLPFC function than with OFC function. Further, only an index of DLPFC test performance was demonstrated to significantly discriminate individuals with and without PD. In conclusion, our findings suggest that nondemented patients with PD exhibit greater impairment on neuropsychological measures associated with DLPFC than with ACC or OFC circuit function.
PMCID: PMC4456005  PMID: 16840240
20.  Altered Resting Functional Connectivity of Expressive Language Regions after Speed Reading Training 
A goal of interventions designed to increase reading speed is to reduce the practice of articulating words in an individual’s thoughts, or subvocalization. This practice may require redundant cognitive resources, slow reading speed, and detract from efficient transfer of written words to semantic understanding. It is unclear, however, whether exercises designed to promote faster reading speed generalize to cognitive function beyond the reading task itself. To investigate this possibility, we measured resting state functional connectivity in classical language regions before and after a course of cognitive exercise designed to increase reading speed in 9 healthy adolescent female volunteers. We found significantly decreased correlation between left Broca Area and right Broca Homologue and between right Broca Homologue and right Wernicke Homologue in the resting state after the training period compared to before training. Differences in functional connectivity after training to left Broca Area showed a spatial distribution reflecting decreased correlation to memory-associated brain regions and increased correlation to auditory regions, that might be consistent with a hypothesis that such training may decrease subvocalization associated with semantic memory function during the resting state.
PMCID: PMC4039565  PMID: 24766286
21.  Hemispheric side of damage influences sex-related differences in smoking cessation in neurological patients 
Patterns of smoking behavior vary between the sexes. There is evidence that decision-making, which is one of the key “executive functions” necessary for making life-style modifications such as smoking cessation, is relatively lateralized to the right hemisphere in males and left hemisphere in females. In the current study, we examined whether the side of brain lesion has a differential effect on smoking behavior between the sexes. We hypothesized sex differences in smoking cessation based on lesion side. Participants were 49 males and 50 females who were smoking at the time of lesion onset. The outcome variable was abstinence from smoking (quit rate) at least one year post lesion. We found that in patients with left hemisphere damage, quit rates were significantly higher in males than in females; however, in patients with right hemisphere damage, quit rates were not statistically different. The findings support previous cognitive neuroscience literature showing that components of behavior responsible for maintaining addiction tend to be more strongly lateralized in males, whereas in females there is a more bilateral distribution. Our study provides further evidence for differences in lateralization of complex behavior between the sexes, which has significant implications for differences in treatment strategies between the sexes.
PMCID: PMC4052374  PMID: 24872115
behavior lateralization; smoking cessation; addiction; gender differences; drug abuse
22.  Neurocognition in College-Aged Daily Marijuana Users 
Marijuana is the most commonly used illicit substance in the United States. Use, particularly when it occurs early, has been associated with cognitive impairments in executive functioning, learning, and memory.
This study comprehensively measured cognitive ability as well as comorbid psychopathology and substance use history to determine the neurocognitive profile associated with young adult marijuana use. College-aged marijuana users who initiated use prior to age 17 (n=35) were compared to demographically-matched controls (n=35).
Marijuana users were high functioning, demonstrating comparable IQs to controls and relatively better processing speed. Marijuana users demonstrated relative cognitive impairments in verbal memory, spatial working memory, spatial planning, and motivated decision-making. Comorbid use of alcohol, which was heavier in marijuana users, was unexpectedly found to be associated with better performance in some of these areas.
This study provides additional evidence of neurocognitive impairment in the context of adolescent and young adult marijuana use. Findings are discussed in relation to marijuana’s effects on intrinsic motivation and discrete aspects of cognition.
PMCID: PMC4074777  PMID: 24620756
marijuana; neurocognition; decision-making; memory; planning
23.  Performance Variability During a Multitrial List-Learning Task as a Predictor of Future Cognitive Decline in Healthy Elders 
In clinical settings, neuropsychological test performance is traditionally evaluated with total summary scores (TSS). However, recent studies demonstrated that indices of intraindividual variability (IIV) yielded unique information complementing TSS. This 18-month longitudinal study sought to determine whether IIV indices derived from a multitrial list-learning test (the Rey Auditory Verbal Learning Test) provided incremental utility in predicting cognitive decline in older adults compared to TSS.
Ninety-nine cognitively intact older adults (aged 65 to 89 years) underwent neuropsychological testing (including the Rey Auditory Verbal Learning Test) at baseline and 18-month follow-up. Participants were classified as cognitively stable (n = 65) or declining (n = 34) based on changes in their neuropsychological test performance. Logistic regression modeling tested the ability of baseline TSS indices (Sum of Trials 1-5, Immediate Recall, and Delayed Recall) and IIV indices (Lost Access and Gained Access) to discriminate between stable and declining individuals.
Higher values of both Lost Access and Gained Access at baseline were associated with an increased risk for decline at 18-month follow-up. Further, the IIV indices provided predictive utility above and beyond the TSS indices.
These results highlight the value of analyzing IIV in addition to TSS during neuropsychological evaluation in older adults. High levels of IIV may reflect impairment in anterograde memory systems and/or executive dysfunction that may serve as a prognostic indicator of cognitive decline.
PMCID: PMC3979935  PMID: 24552205
Intraindividual variability; cognitive aging; prediction of decline; Rey Auditory Verbal Learning Test
24.  The Effect of Parkinson's Disease Subgroups on Verbal and Nonverbal Fluency 
Parkinson's disease (PD) leads to deficits in executive function, including verbal and nonverbal fluency, as a result of compromised fronto-striatal circuits. It is unknown whether deficits in verbal and nonverbal fluency in PD are driven by certain subgroups of patients, or how strategy use may facilitate performance.
Sixty-five non-demented individuals with PD, including 36 with right-body onset (RPD; 20 with tremor as their initial symptom, 16 non-tremor) and 29 with left-body onset (LPD; 14 with tremor as their initial symptom, 15 non-tremor), and 52 normal control participants (NC).
Verbal fluency was assessed using the FAS and Animals tests. Nonverbal fluency was assessed using the Ruff Figural Fluency Test.
Both RPD and LPD were impaired in generating words and in using clustering and switching strategies on phonemic verbal fluency, whereas different patterns of impairment were found on nonverbal fluency depending on the interaction of side of onset and initial motor symptom (tremor vs. non-tremor). Strategy use correlated with number of correct responses on verbal fluency in LPD, RPD, and NC. By contrast, on nonverbal fluency, strategy use correlated with correct responses for RPD and LPD, but not for NC.
Our findings demonstrate the importance of considering subgroups in PD and analyzing subcomponents of verbal and nonverbal fluency (correct responses, errors, and strategies), which may depend differently on the integrity of dorsolateral prefrontal cortex, inferior frontal cortex, and anterior cingulate cortex.
PMCID: PMC4003916  PMID: 24533593
Parkinson's disease; verbal fluency; nonverbal fluency; executive function; prefrontal cortex
25.  Memory for performed and observed activities following traumatic brain injury 
Traumatic brain injury (TBI) is associated with deficits in memory for the content of completed activities. However, TBI groups have shown variable memory for the temporal order of activities. We sought to clarify the conditions under which temporal order memory for activities is intact following TBI. Additionally, we evaluated activity source memory and the relationship between activity memory and functional outcome in TBI participants. Thus, we completed a study of activity memory with 18 severe TBI survivors and 18 healthy age- and education-matched comparison participants. Both groups performed eight activities and observed eight activities that were fashioned after routine daily tasks. Incidental encoding conditions for activities were utilized. The activities were drawn from two counterbalanced lists, and both performance and observation were randomly determined and interspersed. After all of the activities were completed, content memory (recall and recognition), source memory (conditional source identification), and temporal order memory (correlation between order reconstruction and actual order) for the activities were assessed. Functional ability was assessed via the Community Integration Questionnaire (CIQ). In terms of content memory, TBI participants recalled and recognized fewer activities than comparison participants. Recognition of performed and observed activities was strongly associated with social integration on the CIQ. There were no between- or within-group differences in temporal order or source memory, although source memory performances were near ceiling. The findings were interpreted as suggesting that temporal order memory following TBI is intact under conditions of both purposeful activity completion and incidental encoding, and that activity memory is related to functional outcomes following TBI.
PMCID: PMC4148421  PMID: 24524393
Traumatic brain injury; Memory; Source memory; Temporal order memory; Activity memory

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