Differences In Behavioral Measures Research Articles

Parkinson's LRRK2-G2019S risk gene mutation drives sex-specific behavioral and cellular adaptations to chronic variable stress.

Anxiety is a psychiatric non-motor symptom of Parkinson's that can appear in the prodromal period, prior to significant loss of brainstem dopamine neurons and motor symptoms. Parkinson's-related anxiety affects females more than males, despite the greater prevalence of Parkinson's in males. How stress, anxiety and Parkinson's are related and the basis for a sex-specific impact of stress in Parkinson's are not clear. We addressed this using young adult male and female mice carrying a G2019S knockin mutation of leucine-rich repeat kinase 2 ( Lrrk2 G2019S ) and Lrrk2 WT control mice. In humans, LRRK2 G2019S significantly elevates the risk of late-onset Parkinson's. To assess within-sex differences between Lrrk2 G2019S and control mice in stress-induced anxiety-like behaviors in young adulthood, we used a within-subject design whereby Lrrk2 G2019S and Lrrk2 WT control mice underwent tests of anxiety-like behaviors before (baseline) and following a 28 day (d) variable stress paradigm. There were no differences in behavioral measures between genotypes in males or females at baseline, indicating that the mutation alone does not produce anxiety-like responses. Following chronic stress, male Lrrk2 G2019S mice were affected similarly to male wildtypes except for novelty-suppressed feeding, where stress had no impact on Lrrk2 G2019S mice while significantly increasing latency to feed in Lrrk2 WT control mice. Female Lrrk2 G2019S mice were impacted by chronic stress similarly to wildtype females across all behavioral measures. Subsequent post-stress analyses compared cFos immunolabeling-based cellular activity patterns across several stress-relevant brain regions. The density of cFos-activated neurons across brain regions in both male and female Lrrk2 G2019S mice was generally lower compared to stressed Lrrk2 WT mice, except for the nucleus accumbens of male Lrrk2 G2019S mice, where cFos-labeled cell density was significantly higher than all other groups. Together, these data suggest that the Lrrk2 G2019S mutation differentially impacts anxiety-like behavioral responses to chronic stress in males and females that may reflect sex-specific adaptations observed in circuit activation patterns in stress-related brain regions.

Social isolation postweaning alters reward-related dopamine dynamics in a region-specific manner in adolescent male rats

Early development is characterized by dynamic transitions in brain maturation, which may be impacted by environmental factors. Here, we sought to determine the effects of social isolation from postweaning and during adolescence on reward behavior and dopaminergic signaling in male rats. Subjects were socially isolated or group housed at postnatal day 21. Three weeks later, extracellular dopamine concentrations were examined in the medial prefrontal cortex (mPFC) and nucleus accumbens shell (NAc) during a feeding bout. Surprisingly, opposing effects were found in which increased mPFC dopamine concentrations were observed in group housed, but not isolated, rats. In stark contrast, increased dopamine levels were found in the NAc of isolated, but not group housed, rats. Moreover, the absence of an effect in the mPFC of the isolated rats could not be reversed by subsequent group housing, demonstrating the remarkable long-term effects on dopamine signaling dynamics. When provided a highly palatable food, the isolated subjects exhibited a dramatic increase in mPFC dopamine levels when the chocolate was novel, but no effects following chronic chocolate consumption. In contrast, the group housed subjects showed significantly increased dopamine levels only with chronic chocolate consumption. The dopamine changes were correlated with differences in behavioral measures. Importantly, the deficit in reward-related behavior during isolation could be reversed by microinjection of either dopamine or cocaine into the mPFC. Together, these data provide evidence that social isolation from postweaning and during adolescence alters reward-induced dopamine levels in a brain region-specific manner, which has important functional implications for reward-related behavior.

Parkinson's LRRK2-G2019S risk gene mutation drives sex-specific behavioral and cellular adaptations to chronic variable stress.

Anxiety is a psychiatric non-motor symptom of Parkinson's that can appear in the prodromal period, prior to significant loss of midbrain dopamine neurons and motor symptoms. Parkinson's-related anxiety affects females more than males, despite the greater prevalence of Parkinson's in males. How stress, anxiety and Parkinson's are related and the basis for a sex-specific impact of stress in Parkinson's are not clear. We addressed this using young adult male and female mice carrying a G2019S knockin mutation of leucine-rich repeat kinase 2 (Lrrk2 G2019S) and Lrrk2 WT control mice. In humans, LRRK2 G2019S significantly elevates the risk of late-onset Parkinson's. To assess within-sex differences between Lrrk2 G2019S and control mice in stress-induced anxiety-like behaviors in young adulthood, we used a within-subject design whereby Lrrk2 G2019S and Lrrk2 WT control mice underwent tests of anxiety-like behaviors before (baseline) and following a 28 day (d) variable stress paradigm. There were no differences in behavioral measures between genotypes in males or females at baseline, indicating that the mutation alone does not produce anxiety-like responses. Following chronic stress, male Lrrk2 G2019S mice were affected similarly to male wildtypes except for novelty-suppressed feeding, where stress had no impact on Lrrk2 G2019S mice while significantly increasing latency to feed in Lrrk2 WT control mice. Female Lrrk2 G2019S mice were impacted by chronic stress similarly to wildtype females across all behavioral measures. Subsequent post-stress analyses compared cFos immunolabeling-based cellular activity patterns across several stress-relevant brain regions. The density of cFos-activated neurons across brain regions in both male and female Lrrk2 G2019S mice was generally lower compared to stressed Lrrk2 WT mice, except for the nucleus accumbens of male Lrrk2 G2019S mice, where cFos-labeled cell density was significantly higher than all other groups. Together, these data suggest that the Lrrk2 G2019S mutation differentially impacts anxiety-like behavioral responses to chronic stress in males and females that may reflect sex-specific adaptations observed in circuit activation patterns in some, but not all stress-related brain regions.

Emotional Bias among Individuals at Risk for Seasonal Affective Disorder-An EEG Study during Remission in Summer.

Emotional bias in attention and memory is well researched in depression. Patients with depression prioritize processing of negative information over positive input. While there is evidence that emotional bias exists in seasonal affective disorder (SAD) during winter, it is unclear whether such altered cognition exists also during summer. Moreover, it is unclear whether such bias affects attention, memory, or both. In this study, we investigated 110 individuals in summer, 34 of whom reported suffering from low mood during winter, according to the seasonal pattern assessment questionnaire. While the electroencephalogram was recorded, participants learned 60 emotional pictures and subsequently were asked to recognize them in an old/new task. There were no clear group differences in behavioral measures, and no brain response differences in frontal alpha power during learning. During recognition, at 100-300 ms post stimulus individuals with higher seasonality scores exhibited larger alpha power in response to negative as compared to neutral stimuli, while individuals with low seasonality scores exhibited larger alpha power in response to positive as compared to neutral stimuli. While we cannot draw conclusions whether this is an effect of attention or memory, the finding suggests that early cognitive processes are altered already during summer in individuals with increased likelihood to experience SAD during winter. Our data provide evidence for an all-year-round cognitive vulnerability in this population.

Electrophysiological and behavioral assessment of binaural processing: Effects of age

Spatial hearing deteriorates with age, but the basis(es) of this age-dependency is not clear and could reflect both bottom-up and top-down factors. Since binaural processing depends in part on interaural time difference cues, this study assessed binaural temporal acuity using both objective and behavioral measures. Three tasks incorporating interaural time/phase differences were tested: (1) in-phase and out-of-phase frequency modulation (FM) detection as a function of FM rate; (2) upper frequency limit of in-phase versus out-of-phase tone discrimination; and (3) minimum audible angle for low frequency tones. Each task incorporated parallel behavioral and electrophysiological measures: For behavior, forced-choice adaptive methods were employed; for electrophysiology, the acoustic change complex (ACC) was recorded. Additional measures of peripheral auditory function, as well as cognitive status, were also collected. Young and middle-aged adults (n = 20 per age group) with normal audiometric hearing were tested. Differences in behavioral measures of binaural performance were noted between the two age groups and these were reflected to some extent in the ACC results. However, group differences were also noted in terms of cochlear function and in terms of cognitive abilities. This pattern of results suggests that age-related deterioration in spatial perception is likely to be multi-faceted.

The EXPERIENCE system for the investigation of behavioral differences between depressed and healthy-control participants in Virtual Reality

IntroductionThe EXPERIENCE project aims to enable the creation and sharing of extended-personal realities in virtual reality (VR). Currently, software and hardware technology are under development, that will automatically generate VR environments based on neurophysiological, psychological, cognitive, and behavioral data to support not only the recording of personal experiences but the transmission as well to another user. Potential use cases include enhanced treatment and the assessment of symptom severity of affective disorders.ObjectivesThe objective is to design and create a virtual reality environment that enables the identification of between-group differences in behavioral measures when comparing depressed and healthy-control participants.MethodsWe conducted a literature review to identify measures that can be implemented in VR and have the potential to show differences between depressed and healthy-control participants. PubMed and ResearchGate databases were screened to identify potential cognitive tasks. A selection protocol was developed considering effect size, homogeneity of results, risk for cybersickness, cognitive demand, domain heterogeneity, and VR compatibility to choose 4 out of the 47 initial tasks. In addition to the cognitive tasks, behavior measures were considered as well and a virtual environment has been equipped to assess (1) exploratory behavior; (2) engagement with emotionally valenced stimuli (via eye-tracking); (3) metacognitive sensitivity, (4) persistence/grit, and (5) possible effects of mood induction.ResultsBased on the above review, a virtual environment has been developed which is composed of four rooms and a hallway where the starting point is. After an initial tutorial on how the environment/controllers work participants are free to explore and instructions are only provided for the specific cognitive tasks which have to be solved to open the doors and move between rooms. The rooms are equipped with numerous interactive objects and images with varying emotional valence. The engagement with the environment and general activity are continuously recorded and can be retrieved for analyses after participants exit the environment.ConclusionsIf the controlled VR environment will be proven effective for the assessment of depressive symptoms in future studies, the EXPERIENCE system could incorporate direct and objective behavioral measures into the assessment depressive symptoms. Consequently, the system has the potential to support the clinical diagnosis of affective disorders.AcknowledgementThe EXPERIENCE project is funded by the European Commission H2020 Framework Program with the Grant No. 101017727.Disclosure of InterestNone Declared

The impact of mild traumatic brain injury on reading comprehension and eye movements: preliminary results

IntroductionIndividuals who sustain a mild traumatic brain injury (mTBI) can suffer from executive function, working memory, and attention deficits, which can impact functional task performance, including reading comprehension. Individuals with mTBI commonly report reading difficulties, but such difficulties have been historically difficult to capture using behavioral measures. The current study examined reading performance in those with and without mTBI using eye-tracking measures, which may be more sensitive to reading impairment in mTBI. Method/ResultsIn Experiment 1, 26 participants with a history of mTBI and 26 healthy control participants completed working memory (WM) and reading comprehension tasks. We found no differences in behavioral measures but found that spontaneous eye-blinking frequency was lower during the reading task in the mTBI group. In Experiment 2, we explored the impact of auditory distraction (e.g., multi-talker babble) on reading and memory performance. Twenty-three new participants with a history of mTBI and 26 healthy control participants completed a short-term memory (STM) task, a WM task, and a reading comprehension task under two distraction conditions. As in Experiment 1, we found no differences on behavioral measures, but observed significant differences on spontaneous eye-blinking frequency between those with and without mTBI. Group differences in distraction effects were also observed and performance on the WM task predicted reading comprehension performance. ConclusionsThe lack of differences on behavioral measures between groups, but lower frequencies of spontaneous eye blinking in the mTBI group suggests that while these individuals successfully completed the reading comprehension task, they may require more cognitive resources to do so.

Assessment of animal welfare in fattening pig farms certified in good livestock practices

ABSTRACT Commercial swine producers are responsible for implementing changes in their production systems to ensure animal welfare. The objective of this study is to evaluate the levels of animal welfare on rearing and fattening farms certified in good animal husbandry practices using the Welfare Quality® protocol. Eighty-one certified commercial farms (n = 2,150 pigs), distributed in six geographical areas of Colombia, were evaluatedby six trained veterinarians. . A multilevel analysis was performed to identify variables associated with the animal welfare/farm rating and to identify behavioral variables. Farms evaluated had an enhanced (n = 68, 83.9%), followed by excellent (n = 7, 8.7%) and acceptable (n = 6, 7.4%) level of animal welfare. Variables significantly associated with the overall protocol rating (R2 = 0.37) were temperature comfort (OR: 1.05, p = 0.008), absence of disease (OR: 1.06, p = 0.02) and absence of pain (OR: 1.06, p = 0.0001). Significant differences in behavioral measures were observed across farms (P < 0.05). The high animal welfare scores of certified farms suggest changes in producers’ understanding and attitudes towards production and animal welfare.

Non-invasive vagal nerve stimulation enhances cognitive emotion regulation

Transcutaneous auricular vagus nerve stimulation (taVNS) has been proposed as a potential new tool in the treatment of major depressive disorder. Prior studies have demonstrated that taVNS enhances cognitive control and is able to modulate brain activity in key regions involved in cognitive emotion regulation, such as the anterior cingulate and medial prefrontal cortex, which is known to be impaired in depressed patients. Preclinical studies are lacking but may provide important insights into the working mechanisms of taVNS on cognitive emotion regulatory processes. In this between-subject study, 83 healthy subjects underwent a single-session of active taVNS or sham stimulation, after which cognitive reappraisal was examined using a computer-based cognitive emotion regulation task. Our results indicate that participants receiving active taVNS, compared to sham, were better at using cognitive reappraisal and rated their response to emotion-eliciting pictures as less intense. Yet, even though we found significant differences in behavioral measures of cognitive emotion regulation, no differences between groups were found in terms of physiological responses to the emotional stimuli. Overall, these findings suggest a positive effect of taVNS on the cognitive reappraisal of emotions, but future studies assessing objective measures of neural activity during cognitive emotion regulation following taVNS are warranted.

Neural correlates of response inhibition and performance monitoring in binge watching

With increasing popularity of internet streaming portals, the question why people develop excessive binge-watching behavior has become a focus of scientific research. The possible negative consequences of this behavior and its proximity to behavioral addictions are discussed. Since deficits of response inhibition and performance monitoring have been associated with substance use and addictive behaviors, we examined the hypothesis whether frequent binge watching is characterized by alterations in these processes. The current study examined response inhibition in a go/nogo task and performance monitoring in a flanker task using electroencephalography. Participants reported frequent binge-watching episodes (HBW, n = 35) or no binge-watching behavior (NBW, n = 33) during the past four weeks. Compared to the NBW group, HBW showed larger P3a and P3b during response inhibition and larger error-related negativity (ERN) for errors in the flanker task. Group differences in behavioral measures were not observed. The neurocognitive profile associated with frequent binge watching differs from externalizing disorders, such as substance use disorders and addictive behaviors, which are more likely to be associated with diminished amplitudes during response inhibition and performance monitoring. Current findings of increased activity in performance monitoring and inhibition tend to be associated with internalizing disorders. Therefore, symptoms such as anxiety and worry may play a role in the development of binge-watching behavior.

Neural Correlates of Working Memory Deficits in Different Adult Outcomes of ADHD: An Event-Related Potential Study.

BackgroundWe investigated working memory (WM) processing in a longitudinal sample of young adults with persistent and remittent childhood-onset ADHD to investigate the neural correlates of working memory with adult outcomes of ADHD.MethodsForty-seven young Chinese adults who had been diagnosed with ADHD during childhood underwent follow-up assessments for an average of 9 years. The ADHD sample consisted of 25 ADHD persisters (mean age =18.38 ± 0.5 years) and 22 remitters (mean age = 18.78 ± 1.10 years), who were compared with 25 sex ratio- and IQ-matched healthy adults (mean age = 19.60 ± 1.22 years) in a verbal n-back task.ResultsNo differences in behavioral measures were observed across the three groups. Compared with the healthy controls, the ADHD persisters and remitters had larger N1 amplitudes and smaller P2 amplitudes, while no significant differences between the persistence and remission groups were observed. The P3 amplitudes of the remission and control groups were higher than that of the persistence group, but there was no significant difference between the remitters and healthy controls.ConclusionThe P3 amplitudes reflecting postdecisional processing and/or WM updating were sensitive to ADHD remission, as they might improve concurrently with ADHD symptoms. These results indicate that the N1, P2, and P3 components of WM processing might be potential biomarkers for different ADHD outcomes.

Randomized controlled trial of d-cycloserine in cocaine dependence: Effects on contingency management and cue-induced cocaine craving in a naturalistic setting.

Cocaine dependence constitutes a significant public health concern. This randomized, double-blind, placebo-controlled trial tested a novel approach to reducing cocaine use among cocaine-dependent individuals with d-cycloserine, a drug known to enhance learning and some learning-based therapies. Urine samples and cocaine craving were assessed across three phases: induction (Weeks 1-2), treatment (Weeks 3-5; urinalysis-based contingency management plus exposure therapy), and posttreatment (Weeks 6-7). During the treatment phase, either 50 mg of d-cycloserine or placebo was administered after delivery of urinalysis feedback with potential monetary reward and before exposure therapy sessions in naturalistic contexts individually associated with cocaine use. d-cycloserine significantly improved learning on an operant laboratory task. Contingency management significantly reduced cocaine use and craving. d-cycloserine did not significantly affect cocaine use or craving in the treatment phase. Craving significantly increased for the d-cycloserine group during the post treatment phase. Therefore, although the study showed that d-cycloserine was capable of improving learning, enhancement of learning-based therapy was not observed. Moreover, no differences in behavioral measures of cocaine demand (cocaine purchasing task) or monetary or sexual delay discounting were observed across phases or between groups in any phase. These results are somewhat consistent with previous findings suggesting that d-cycloserine administration increases cocaine craving, although they differ from other findings showing that d-cycloserine administration reduces alcohol or nicotine cravings. Methodological variables (e.g., guided vs. unguided exposure therapy sessions, length of extinction exposure) likely play a role in dissimilar findings observed across studies. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Neurophysiological and Interpersonal Correlates of Emotional Face Processing in Alcohol Use Disorder.

A growing literature suggests deficient emotional facial expression (EFE) processing among recently abstinent individuals with alcohol use disorders (AUDs). Further investigation is needed to clarify valence-related discrepancies and elucidate neural and psychosocial correlates. We examined neurobehavioral indices of EFE processing and interpersonal problems in treatment seekers with AUDs and healthy community controls (CCs). Thirty-four individuals with AUDs and 39 CCs completed an emotion judgment task (EJT), requiring discrimination between happy, angry, and sad EFEs. A second task requiring discrimination of male and female faces with neutral expressions served as the control task (i.e., sex judgment task, SJT). Neurophysiological (i.e., N170 and P3) and behavioral measures were analyzed using generalized linear mixed models (GLMM). Interpersonal problems were assessed with the Inventory of Interpersonal Problems-64 (IIP-64). The relationship of IIP-64 and EJT performance was investigated via within-group correlations. Analysis of the SJT revealed no group differences in behavioral measures, N170 amplitude, or P3 latency. P3 amplitudes, however, were significantly lower in the AUD group. For the EJT, initial observations of group differences in P3 amplitude were accounted for by differences in the control task. Behavioral analyses indicated that the AUD group was significantly less accurate than the CC group. Hypothesis-driven analyses using GLMM-estimated group differences indicated that anger processing was affected to a greater degree than were other emotions. Significant EJT/IIP-64 correlations were observed for anger processing within the AUD group and were confined to IIP-64 subscales with relatively high ratings on the affiliation dimension. Findings provide partial support for an emotion-specific processing deficit in persons with AUDs. Anger processing was more robustly affected than other emotions and was associated with interpersonal problems characterized by being overly needy, nonassertive, and overly accommodating. Results extend prior reports and reinforce the need for comprehensive study of emotion processing and its real-world implications.

Social and anxiety-like behaviors contribute to nicotine self-administration in adolescent outbred rats

Both emotional and social traits interact with genetic factors to influence smoking behavior. We previously established a socially acquired nicotine intravenous self-administration model where social learning of a nicotine-associated odor cue reversed conditioned flavor aversion and promoted nicotine intake. In this study, we first phenotyped ~800 adolescent heterogeneous stock rats in open field, novel object interaction, social interaction, elevated plus maze, and marble burying behaviors. These rats were then phenotyped on socially acquired nicotine self-administration. We found 243 significant correlations between different behavioral tests. Principal component regression analysis found that ~10–20% of the variance in nicotine-related measures, such as intake during the first or the last three fixed-ratio sessions, the progressive ratio session, and reinstatement behavior, can be explained by variations in behavioral traits. Factors corresponding to social behavior and anxiety were among the strongest predictors of nicotine intake and reinstatement of nicotine-seeking behavior. We also found many sex differences in behavioral measures. These data indicated that the genetic diversity of this population, in combination with social behaviour and anxiety, are significant contributors to the divergent nicotine self-administration behavior and indicated a high probability of discovering sex-specific genetic mechanisms for nicotine intake in future genome-wide association studies.

Cortical morphology of the pars opercularis and its relationship to motor-inhibitory performance in a longitudinal, developing cohort

This study investigates the relationship between variability in cortical surface area and thickness of the pars opercularis of the inferior frontal gyrus and motor-inhibitory performance on a stop-signal task in a longitudinal, typically developing cohort of children and adolescents. Linear mixed-effects models were used to investigate the hypotheses that (1) cortical thinning and (2) a relatively larger cortical surface area of the bilateral pars opercularis of the inferior frontal gyrus would predict better performance on the stop-signal task in a cohort of 110 children and adolescents 4–13 years of age, with one to four observations (totaling 232 observations). Cortical thickness of the bilateral opercular region was not related to inhibitory performance. However, independent of age, gender, and total cortical surface area, relatively larger cortical surface area of the bilateral opercular region of the inferior frontal gyrus was associated with better motor-inhibitory performance. Follow-up analyses showed a significant effect of surface area of the right pars opercularis, but no evidence for an effect of area of left pars opercularis, on motor-inhibitory performance. These findings are consistent with the previous work in adults showing that cortical morphology of the pars opercularis is related to inhibitory functioning. It also expands upon this literature by showing that, in contrast to earlier work highlighting the importance of cortical thickness of this region in adults, relative cortical surface area of the pars opercularis may be related to developing motor-inhibitory functions during childhood and adolescence. Relationships between cortical phenotypes and individual differences in behavioral measures may vary across the lifespan.

On the Neuroscience of Self-Regulation in Children With Disruptive Behavior Problems

Self-regulation is increasingly recognized as a key predictor of academic and social competence. A multidisciplinary understanding of this ability is timely and can strengthen theory and practice. The present review aims to inform educators on what cognitive neuroscience can teach us about self-regulation. To do so, we will focus on a decade-long research program examining children with disruptive behavior problems and their peers, and ask whether neural measures of self-regulation can (a) covary with individual differences in behavioral measures of self-regulation, (b) trace developmental patterns, and (c) predict or trace behavioral change with successful treatment of disruptive behavior problems. We show that several studies begin to converge on a set of neural measures derived from the prefrontal cortex that can be consistently linked to processes of self-regulation. Next, we will discuss what these measures mean from a cognitive neuroscience perspective and how this knowledge could influence and/or support psychological models relevant to education.

Commentary on the special issue on the adolescent brain: A tribute to the adolescent brain

Sex differences in brain and behavior were investigated across the lifespan. Parameters include neurobehavioral measures linkable to neuroanatomic and neurophysiologic indicators of brain structure and function. Sexual differentiation of behavior has been related to organizational factors during sensitive periods of development, with adolescence and puberty gaining increased attention. Adolescence is a critical developmental period where transition to adulthood is impacted by multiple factors that can enhance vulnerability to brain dysfunction.Here we highlight sex differences in neurobehavioral measures in adolescence that are linked to brain function. We summarize neuroimaging studies examining brain structure, connectivity and perfusion, underscoring the relationship to sex differences in behavioral measures and commenting on hormonal findings. We focus on relevant data from the Philadelphia Neurodevelopmental Cohort (PNC), a community-based sample of nearly 10,000 clinically and neurocognitively phenotyped youths age 8–21 of whom 1600 have received multimodal neuroimaging. These data indicate early and pervasive sexual differentiation in neurocognitive measures that is linkable to brain parameters. We conclude by describing possible clinical implications.

Motor overflow in children with attention-deficit/hyperactivity disorder is associated with decreased extent of neural activation in the motor cortex

Motor overflow is a developmental phenomenon that typically disappears by late childhood. Abnormal persistence of motor overflow is often present in children with attention-deficit/hyperactivity disorder (ADHD). This study employed functional magnetic resonance imaging (fMRI) during a finger-sequencing task to examine whether excessive motor overflow in children with ADHD is associated with decreased extent of motor circuit activation. Thirty-four right-handed children (18 typically developing controls, 16 ADHD) completed fMRI while performing a finger-sequencing task. Motor overflow was evaluated during a finger-sequencing task and a motor examination (the PANESS) performed outside the scanner. Diagnostic differences in behavioral measures of overflow and extent of activation in the contralateral and ipsilateral motor network ROIs were examined, along with correlations between overflow and extent of activation. Children with ADHD demonstrated greater overflow and lesser extent of activation in left primary motor cortex (BA4) and bilateral premotor cortex (BA6) and supplementary motor area (SMA) during right-hand finger-sequencing compared to controls. Decreased extent of primary motor and premotor activation correlated with increased hand-related overflow movements in children with ADHD but not controls. These findings suggest that overflow movements in children with ADHD may reflect decreased recruitment of neural circuitry involved in active inhibition of homologous motor circuitry unnecessary to task execution.

Efficiency of Arithmetic Procedures Modulates the Problem-Size Effect in Subtraction.

The aim of this study was to examine whether differences in strategy selection and/or strategy efficiency can explain the modulation of the problem-size effect by arithmetic skill. More specifically, we wondered whether arithmetic skill increases the use of retrieval strategy in large problems, and/or enhances the efficiency of either retrieval or procedural strategies. The performance of highly-skilled (HS) and less highly-skilled (LS) individuals on a subtraction verification task was analyzed according to problem size and to the strategy reported on a trial-by-trial basis after each problem. The problem size effect was larger for LS individuals than for their HS peers, both in response time and in hit rate. Nevertheless, groups did not differ regarding the strategy reported for each subtraction size. As expected, problems in which retrieval strategy was reported were solved more quickly and more accurately than problems solved by procedural strategies. Responses using retrieval strategy were equally fast in the two groups, but HS individuals performed better than LS when using procedural strategies. The results therefore suggest that the differences in behavioral measures between groups might specifically be due to differences in the efficiency of procedural strategies.

Expression of cFos and brain-derived neurotrophic factor in cortex and hippocampus of ethanol-withdrawn male and female rats

Objective:To map areas of brain activation (cFos) alongside changes in levels of brain-derived neurotrophic factor (BDNF) to provide insights into neuronal mechanisms contributing to previously observed sex differences in behavioral measures of ethanol withdrawal (EW).Materials and Methods:Immunohistochemical analysis of cFos and BDNF levels using protein-specific antibodies and visualization with nickel-enhanced DAB staining in 3 cortical and 4 hippocampal regions was used to assess EW-induced expression of these proteins.Results:EW male and female rats showed significantly higher levels of cFos expression compared to controls in the hippocampal regions whereas EW OVX rats showed higher levels compared to controls only at 1 day EW in the dentate gyrus. Males expressed higher basal levels of cFos in the CA1 subfield of the hippocampus and in the motor cortex than either intact or OVX female rats. BDNF immunoreactivity was also significantly higher in EW rats compared to that in controls, varying with sex and brain region at 1 and 3 days EW.Conclusions:Sex-and brain region-specific changes in expression of cFos and BDNF occurring during 1 and 3-day EW, suggest that differential activation and expression of neurotrophins may influence the observed sex differences and support the suggestion that EW is a chronic stressor, eliciting sequential neuronal activation and neurotrophin regulation.