It is more than Interference: Examining the neurohemodynamic correlates of the flanker task with functional near‐infrared spectroscopy

Previous functional near‐infrared spectroscopy studies using the Eriksen flanker task, in contrast to functional magnetic resonance imaging studies, revealed the quite puzzling finding of an inverted conflict effect, that is, greater middle and superior frontal activation in response compatible than in response incompatible trials. However, since neither prior functional near‐infrared spectroscopy studies nor most previous functional magnetic resonance imaging studies separated between an identical and a compatible condition, it is hard to pinpoint whether this discrepancy occurs on the level of stimulus processing or response generation. By assigning two letters to both left (D, F) and right (J, K) hand reactions, we were able to separate identical (e.g., JJJ) and compatible (e.g., JKJ) conditions that solely differ in their stimulus congruency. Replicating prior functional magnetic resonance imaging findings, we found the standard conflict effect at the transition of superior and middle frontal gyrus, when comparing the activation in compatible trials to that in incompatible trials. Both changes in oxygenated and deoxygenated hemoglobin thus pointed to more effortful processing in incompatible trials. Interestingly, however, identical trials showed the highest activation in this region, according to both changes in oxygenated and deoxygenated blood. A finding that mirrors and extends prior functional near‐infrared spectroscopy findings, which only regarded oxygenated blood. We argue that this pattern of results does not reflect the standard conflict effect. We rather assume that other processes like perceptual familiarity or strategic readjustment might be at play.     

MILD EXECUTIVE DYSFUNCTIONS IN UNDERGRADUATES ARE RELATED TO RECOLLECTING WORDS NEVER PRESENTED

The aim of this study was to explore whether individual differences in executive function in undergraduate students (n = 72) contribute to false recall and recognition as obtained with the Deese/Roediger-McDermott (DRM) paradigm. Participants were subjected to the DRM paradigm and also were given a test designed to assess executive function-–the Random Number Generation task (RNG). A relationship was found between heightened seriation on the RNG (indicating a deficiency in the ability to inhibit cognitive schemes) and false recognition of non-presented, critical lure words in the DRM paradigm. This suggests that individual differences in executive function do occur in a healthy population and that the reconstructive activity inherent in memory depends in part on executive functioning.     

Prefrontal-subcortical dissociations underlying inhibitory control revealed by event-related fMRI

Using event-related fMRI, this study investigated the neural dynamics of response inhibition under fluctuating task demands. Fourteen participants performed a GO/NOGO task requiring inhibition of a prepotent motor response to NOGO events that occurred as part of either a Fast or Slow presentation stream of GO stimuli. We compared functional activations associated with correct withholds (Stops) required during the Fast presentation stream of stimuli to Stops required during the Slow presentation stream. A predominantly right hemispheric network was activated across conditions, consistent with previous studies. Furthermore, a functional dissociation of activations between conditions was observed. Slow Stops elicited additional activation in anterior dorsal and polar prefrontal cortex and left inferior parietal cortex. Fast Stops showed additional activation in a network that included right dorsolateral prefrontal cortex, insula and dorsal striatum. These results are discussed in terms of our understanding of the impact of preparation on the distributed network underlying response inhibition and the contribution of subcortical areas, such as the basal ganglia, to executive control processes.     

Variability of the paracingulate sulcus and morphometry of the medial frontal cortex: associations with cortical thickness, surface area, volume, and sulcal depth

The structural and functional consequences of interindividual variations in cortical morphology are poorly understood. In this study, we examined the relationship between one well-characterized variation of the medial frontal lobes, variability of the paracingulate sulcus (PCS), and grey matter volume, cortical thickness, surface area, and sulcal depth of the adjacent anterior cingulate cortex (ACC) and paracingulate cortex (PaC). Seventy-seven healthy individuals were assigned to one of four groups depending on PCS incidence in both hemispheres: left-present, right-absent; left-absent, right-present; both absent; or both present. Comparing these groups on each measure yielded four primary findings: (1) The presence of a PCS was associated with increased PaC and decreased ACC grey matter volume in the hemisphere in which it was apparent, with an almost identical pattern being observed for surface area; (2) there was a more complex relationship between PCS variability and regional thickness, such that a PCS in the left hemisphere was associated with increased left PaC and right ACC thickness, with no comparable effects being observed for the presence of a right PCS; (3) the depths of all major left hemisphere sulci in the region were strongly positively correlated, whereas no such associations were apparent in the right hemisphere; and (4) a leftward asymmetry in PaC thickness was specifically associated with better performance on a test of spatial working memory ability. These results provide evidence for a complex interhemispheric relationship between sulcal variability and cortical morphometry, and indicate that such relationships may be important for understanding individual differences in cognitive abilities.     

Cerebral plasticity and recovery of function after childhood prefrontal cortex damage

Objective: Recovery of function after early brain injury depends upon both reparative and compensatory processes that are minimally understood. Using functional magnetic resonance imaging (fMRI), this study investigated the reorganization of hemispheric brain activity of a 24 year old male who suffered right prefrontal cortex damage at 7 years of age related to ruptured arteriovenous malformation. His pattern of recovery has been examined and tracked over the past 17 years and evolved from initial significant impairments in executive, spatial and attentional abilities from the brain lesion to remarkable recovery of function.

Methods: High field fMRI studies were completed with experimental cognitive tasks sensitive to right prefrontal functions, including visuospatial relational reasoning, spatial working memory, go no-go, emotional face recognition, and coin calculation. Results were compared to a matched control group for total hemispheric activity patterns.

Results: Analyses revealed that on fMRI activation tasks where the patient scored similar to controls, he activated a broader network of bilateral cortical regions than controls. On tasks where he scored lower than controls, there was under-activation of prefrontal cortical regions in comparison to controls.

Conclusion: Recovery of function after prefrontal cortex damage in childhood can occur and be associated with significant functional reorganization of hemispheric activity patterns (i.e. developmental cerebral plasticity). Although not all tasks showed recovery to the same extent in this case, those tasks with the most robust recovery entailed compensatory activation of additional cortical regions on fMRI. Further studies are needed to confirm and extend these findings.     

SLEEP QUALITY AND IMMUNE FUNCTIONS IN RHEUMATOID ARTHRITIS PATIENTS WITH AND WITHOUT MAJOR DEPRESSION

The purpose of this study was to determine the discriminative factors between rheumatoid arthritis (RA) patients with and without major depression (MD). We assessed subjective sleep quality, pain, and cell-mediated immune functions in RA patients with (n = 20) and without (n = 20) MD by using Pittsburgh Sleep Quality Index (PSQI), visual analogue scale (VAS), and fluorescein isothiocyanat (FITC) labeled CD3, CD4, CD8, CDI9, CD45, CD56, and HLADR T monoclonal antibodies by flow cytometry. We found that the RA patients with MD had significantly higher pain level, poorer sleep equality, higher HDRS points, and higher HLADR T cell level than those without MD; and that these variables are discriminant factors between patient groups. These findings suggest that the RA patients with MD may be differentiated from those without MD by using VAS, PSQI, and HLADR levels; that these variables correctly classify the depressed and non-depressed groups up to an accuracy level of 96.8%     

ELECTROENCEPHALOGRAPHIC,PERSONALITY, AND EXECUTIVE FUNCTION MEASURES ASSOCIATED WITH FREQUENT MOBILE PHONE USE

The present study employs standardized data acquired from the Brain Resource International Database to study the relationship between mobile phone usage, personality, and brain function (n = 300). Based on the frequency and duration of mobile phone usage, three groups were formed. The findings suggest a subtle slowing of brain activity related to mobile phone use that is not explained by differences in personality. These changes are still within normal physiological ranges. Better executive function in mobile phone users may reflect more focused attention, possibly associated with a cognitive training effect (i.e., frequently making phone calls in distracting places), rather than a direct effect of mobile phone use on cognition.     

The role of migraine headache severity,associated features and interactions with overweight/obesity in inhibitory control

Aim of the Study: While migraine and obesity are related and both conditions are associated with reduced executive functioning, no study has examined whether obesity exacerbates executive dysfunction in migraine. This cross-sectional study examined whether overweight/obesity moderated associations of migraine severity and associated features with inhibitory control, one aspect of executive function.

Materials and Methods: Women (n = 124) aged 18–50 years old with overweight/obesity body mass index (BMI) = 35.1 ± 6.4 kg/m² and migraine completed a 28-day smartphone-based headache diary assessing migraine headache severity (attack frequency, pain intensity) and frequency of associated features (aura, photophobia, phonophobia, nausea). They then completed computerized measures of inhibitory control during an interictal (headache-free) period.

Results: Participants with higher migraine attack frequency performed worse on the Flanker test (accuracy and reaction time; p < .05). Migraine attack frequency and pain intensity interacted with BMI to predict slower Stroop and/or Flanker Reaction Time (RT; p < .05). More frequent photophobia, phonophobia and aura were independently related to slower RT on the Stroop and/or Flanker tests (p < .05), and BMI moderated the relationship between the occurrence of aura and Stroop RT (p = .03).

Conclusions: Associations of migraine severity and presence of associated features with inhibitory control varied by BMI in overweight/obese women with migraine. These findings warrant consideration of weight status in clarifying the role of migraine in executive functioning.     

Autobiographical memory, the sense of recollection and executive functions after severe traumatic brain injury

Residual disorders of autobiographical memory long after trauma resulting from head injury are rarely assessed, even though they may affect social adjustment and the resumption of daily life. We conducted a thorough study of autobiographical memory in severe traumatic brain injury (TBI) patients, examined at least one year post-trauma. Twenty-five patients were submitted to a novel and controlled autobiographical procedure specially designed to measure episodic memories (i.e., unique, specific in time and space, and detailed) from their entire life span with two kinds of self-remembering experience. The ability to mentally travel back through time and re-experience the source of acquisition, i.e. autonoetic consciousness, was assessed via the "Remember/Know" paradigm and a checking procedure of sense of remembering. Self-perspective in visual imagery, which is also critically involved in episodic recollection, was assessed by the "Field/Observer perspective" paradigm. In addition, the patients underwent a battery of standardized neuropsychological tests to assess episodic and semantic memory, orientation and executive functions. The results showed that the patients, compared with healthy controls, were significantly impaired in recalling episodic autobiographical memories. This impairment was not related to the life period tested or the patients' ages nor the intellectual impairment. Deficits involved disturbances in sense of remembering, visual imagery self-perspective and recollection of spatiotemporal details. Stepwise-regression analyses carried out in the TBI patients revealed a significant relationship between an abnormal sense of remembering and executive dysfunction covering both anterograde and retrograde components. The novel assessment used in this study provides the first detailed evidence of a more fine-grained deficit of autobiographical memory in TBI patients. Indeed, the results suggest that these patients, long after trauma, present autonoetic consciousness and self-perspective disorders, which include sense of identity (the self) as a continuous entity across time, probably related to frontal dysfunction.     

Social reasoning skills in adults with Down syndrome: the role of language,executive functions and socio‐emotional behaviour

Background Although the prevalence of mental illness and behaviour problems is lower in adults with Down syndrome (DS) than in other populations with intellectual disabilities, they do present emotional and relational problems, as well as social integration difficulties. However, studies reporting on specific competences known to be central in developing appropriate social relationships (e.g. social reasoning, emotion processing, theory of mind) remain rare in the adult DS population and the mechanisms underlying these people's emotional and relational difficulties are unclear. Method The present study investigated the ability to understand the appropriateness of others' social behaviour in 34 adults with DS, using the Social Resolution Task (SRT). Their results were compared with those of 34 typically developing (TD) children matched for gender and receptive vocabulary. The relationships among the SRT experimental task, cognitive competences (receptive and productive vocabulary, non‐verbal reasoning, inhibition, selective attention) and a caregiver‐rated measure of socio‐emotional behaviour were examined in the DS group. Results The DS participants' global SRT scores did not differ from those of the controls. However, analyses of the SRT subscores revealed that the DS group identified significantly fewer inappropriate situations than the control group. Nevertheless, when they correctly identified the behaviour as inappropriate, they were as well as the controls to explain the rules underlying their responses. Regression analyses showed that receptive vocabulary and selective attention and a specific dimension of the socio‐emotional profile (social relating skills) constituted the best predictors of the DS adults' performance on the SRT. Conclusions The main findings show that the DS participants demonstrate relatively good social reasoning skills in comparison with TD children matched for verbal age. However, the two groups present distinctions in their response patterns, and the influence of cognitive variables on success on the SRT also appears different. While selective attention skills are found to be significant predictors for both groups, the influence of receptive vocabulary level is much stronger in the DS group. The implications of particular cognitive and socio‐emotional factors for success on the SRT in this group are considered in more detail.     

Brief Communication: EVALUATION OF THYROID AND PARATHYROID FUNCTIONS IN CHILDREN RECEIVING LONG-TERM CARBAMAZEPINE THERAPY

We studied serum calcium, phosphorus, alkaline phosphatase (ALP), thyroid hormones (total thyroxine [TT4], free thyroxine [FT4], thyroid-stimulating hormone [TSH]), parathyroid hormone (PH), and osteocalcine levels in children with epilepsy who had been receiving long-term carbamazepine (CBZ) therapy to determine whether there was any effect of CBZ therapy on these hormones. The study included 18 patients with epilepsy receiving CBZ and 16 healthy age-matched controls. The age ranged from 4-18 years (11.26 &#45 3.59 years) and 4.5-17 years (11.16 &#45 3.13 years) in the study and control group, respectively. The duration of CBZ use was between 10 months-5 years (3.12 &#45 1.09 years). When comparing the results we did not find any significant difference in serum calcium, phosphorus, ALP, osteocalcine and TSH and PH levels between the groups (p >. 05). However, serum TT4 and FT4 levels were found to be significantly lower in the study group than those of control group (p <. 05). However, we observed no clinical signs of hypothyroidism in all subjects. To these findings we suggest that serum thyroid hormone levels should be monitored in children receiving long-term CBZ therapy.­­     

A PREFRONTAL ERP INVOLVED IN DECISION MAKING DURING VISUAL DURATION AND SIZE DISCRIMINATION TASKS

Recently, a late positive component (LPCt) with prefrontal dominance was identified in a duration discrimination task as a marker of decision-making processes (Paul et al., 2003). In the present study, LPCt amplitudes and latencies were measured in visual and size discrimination tasks for the purpose of determining the selectivity of this phenomenon. LPCt amplitudes were larger and latencies shorter for longer stimulus pairs, at a time of maximal behavioral performances. Wave amplitudes were also larger for smaller stimuli, but were not directly related to behavioral performances. These results indicate that the LPCt is not specific to temporal discrimination but can reflect more general decision-making processes.     

Brief Communication: NO EFFECT OF LONG-TERM VALPROATE THERAPY ON THYROID AND PARATHYROID FUNCTIONS IN CHILDREN

In this study, we studied serum calcium, phosphorus, alkaline phosphatase, thyroid hormones (total thyroxine, free thyroxine, thyroid-stimulating hormone), parathyroid hormone, and osteocalcine levels in children with epilepsy who had been receiving long-term valproate (VPA) therapy in order to determine whether there was any effect of VPA therapy on these hormones. The study included 31 patients with epilepsy receiving VPA and 22 healthy age-matched controls. The age ranged from 15 months to 16 years and 18 months to 17 years in the study and control group, respectively. The duration of VPA use was between 12 months and 5 years (1.93 &#45 1.90 years). When comparing the results, we did not find any significant difference in any of the parameters, including serum calcium, phosphorus, alkaline phosphatase, osteocalcine, and thyroid and parathyroid hormone levels, between the study and control group. We suggest that VPA can safely be used with regard to thyroid and parathyroid dysfunction in childhood epilepsy.     

Evidence of motor-control difficulties in children with attention deficit hyperactivity disorder,explored through a hierarchical motor-systems perspective

Introduction: Attention deficit hyperactivity disorder (ADHD) may reflect a disorder of neural systems that regulate motor control. The current study investigates motor dysfunction in children with ADHD using a hierarchical motor-systems perspective where frontal–striatal/“medial” brain systems are viewed as regulating parietal/“lateral” brain systems in a top down manner, to inhibit automatic environmentally driven responses in favor of goal-directed behavior. It was hypothesized that due to frontal–striatal hypoactivation, children with ADHD would have difficulty with higher order motor control tasks felt to be dependent on these systems, yet have preserved general motor function. Method: A total of 63 children—ADHD and matched controls—completed experimental motor tasks that required maintenance of internal motor representations and the ability to inhibit visually driven responses. Children also completed a measure of motor inhibition, and a portion of the sample completed general motor function tasks. Results: On motor tasks that required them to maintain internal motor representations and to inhibit automatic motor responses, children with ADHD had significantly greater difficulty than controls, yet on measures of general motor dexterity, their performance was comparable. Children with ADHD displayed significantly greater intraindividual (subject) variability than controls. Intraindividual variability (IIV) contributed to variations in performance across the motor tasks, but did not account for all of the variance on all tasks. Conclusions: These findings suggest that children with ADHD may be more controlled by external stimuli than by internally represented information, possibly due to dysfunction of the medial motor system. However, it is likely that children with ADHD also display general motor-execution problems (as evidenced by IIV findings), suggesting that atypicalities may extend to both medial and lateral motor systems. Findings are interpreted within the context of contemporary theories regarding motor dysfunction in ADHD, and implications for understanding externalizing behaviors in ADHD are discussed.     

A COMPARISON OF THE CLOCK DRAWING TEST AND THE PFEIFFER SHORT PORTABLE MENTAL STATUS QUESTIONNAIRE IN A GEROPSYCHIATRY CLINIC

Wolf-Klein and colleagues' clock drawing test (CDT) performance was compared with Pfeiffer's Short Portable Mental Status Questionnaire (Pfeiffer) scores in 145 outpatient geropsychiatry patients. Although normal CDT results were almost always associated with normal Pfeiffer scores, 21% of Pfeiffer normal individuals drew abnormal clocks. Age, but not gender or education, was significantly associated with this finding. Almost all the Pfeiffer normal subjects who drew abnormal clocks were diagnosed with primary psychiatric disorders (85%) or neurologically based organic mood and anxiety disorders (12%); only one (3%) had dementia. We suggest the discrepant performance between the CDT and Pfeiffer may result from psychiatric illness. Contributing to this may be CDT sensitivity to executive skills dysfunction. This dyscontrol can occur in patients with dementia and other neurological disorders, but also presents in some primary mental disorders. Older age may heighten this impairment. In a typical geropsychiatry clinic, the CDT will not have high specificity for Alzheimer's disease as reported by Wolf-Klein and her colleagues. This results from the presence of many patients with primary psychopathology, some of whom will draw abnormal clocks, and a limited number with dementia—particularly Alzheimer's disease. Abnormal CDT results of geropsychiatry outpatients must therefore be interpreted carefully. Additional conclusions regarding the study results are discussed. © 1997 John Wiley & Sons, Ltd.     

CLASSICAL AND ATYPICAL NEUROLEPTICS,AND BONE MINERAL DENSITY,IN PATIENTS WITH SCHIZOPHRENIA

There are some reports that classical neuroleptics may lead to osteoporosis or reduced bone mineral density (BMD). However, there is no adequate information about the effects of atypical neuroleptics on BMD. The aim of this study was to measure BMD in schizophrenic patients taking class -ical and atypical neuroleptics, compared to healthy controls. Seventy- five patients with schizophrenia (40 taking classical neuroleptics [CN], 35 taking atypical neuroleptics [AN]) and 20 healthy controls (HC) were included in the study. Spine (L1 L4) BMD was measured by dual-energy X-ray absorptiometry. ANOVA showed that BMD was higher in HC than AN and CN. In addition, there was a negative correlation between the duration of neuroleptic treatment and BMD and the duration of the illness. These findings suggest that atypical neuroleptics may be safer than the classical neuroleptics in terms of reduced BMD.     

NONLINEAR INTERDEPENDENCE IN NEURAL SYSTEMS: MOTIVATION,THEORY, AND RELEVANCE

In this article, we motivate models of medium to large-scale neural activity that place an emphasis on the modular nature of neocortical organization and discuss the occurrence of nonlinear interdependence in such models. On the basis of their functional, anatomical, and physiological properties, it is argued that cortical columns may be treated as the basic dynamical modules of cortical systems. Coupling between these columns is introduced to represent sparse long-range cortical connectivity. Thus, neocortical activity can be modeled as an array of weakly coupled dynamical subsystems. The behavior of such systems is represented by dynamical attractors, which may be fixed point, limit cycle, or chaotic in nature. If all the subsystems are perfectly identical, then the state of identical chaotic synchronization is a possible attractor for the array. Following the introduction of parameter variation across the array, such a state is not possible, although two other important nonlinear interdependences--generalized and phase synchronized--are possible. We suggest that an understanding of nonlinear interdependence may assist advances in models of neural activity and neuroscience time series analysis.