Reduced prefrontal hemodynamic response in adult attention‐deficit hyperactivity disorder as measured by near‐infrared spectroscopy

Aim

Recent developments in near‐infrared spectroscopy (NIRS) have enabled non‐invasive clarification of brain functions in psychiatric disorders. In pediatric attention‐deficit hyperactivity disorder (ADHD), reduced prefrontal hemodynamic responses have been observed with NIRS repeatedly. However, there are few studies of adult ADHD by multi‐channel NIRS. Therefore, in this study, we used multi‐channel NIRS to examine the characteristics of prefrontal hemodynamic responses during the Stroop Color–Word Task (SCWT) in adult ADHD patients and in age‐ and sex‐matched control subjects.

Methods

Twelve treatment‐naïve adults with ADHD and 12 age‐ and sex‐matched healthy control subjects participated in the present study after giving consent. We used 24‐channel NIRS to measure the oxygenated hemoglobin (oxy‐Hb) changes at the frontal lobes of participants during the SCWT. We compared the oxy‐Hb changes between adults with ADHD and control subjects by t ‐tests with Bonferroni correction.

Results

During the SCWT, the oxy‐Hb changes observed in the ADHD group were significantly smaller than those in the control group in channels 11, 16, 18, 21, 22, 23, and 24, corresponding to the prefrontal cortex. At channels 16, 21, 23, and 24 of the ADHD group, there were negative correlations between the symptomatic severity and the oxy‐Hb changes.

Conclusion

The present study suggests that adults with ADHD have reduced prefrontal hemodynamic response as measured by NIRS.

     

Using spaced retrieval and Montessori‐based activities in improving eating ability for residents with dementia

Objectives

To construct a training protocol for spaced retrieval (SR) and to investigate the effectiveness of SR and Montessori‐based activities in decreasing eating difficulty in older residents with dementia.

Methods

A single evaluator, blind, and randomized control trial was used. Eighty‐five residents with dementia were chosen from three special care units for residents with dementia in long‐term care facilities in Taiwan. To avoid any confounding of subjects, the three institutions were randomized into three groups: spaced retrieval, Montessori‐based activities, and a control group. The invention consisted of three 30–40 min sessions per week, for 8 weeks.

Results

After receiving the intervention, the Edinburgh Feeding Evaluation in Dementia (EdFED) scores and assisted feeding scores for the SR and Montessori‐based activity groups were significantly lower than that of the control group. However, the frequencies of physical assistance and verbal assistance for the Montessori‐based activity group after intervention were significantly higher than that of the control group, which suggests that residents who received Montessori‐based activity need more physical and verbal assistance during mealtimes. In terms of the effects of nutritional status after intervention, Mini‐Nutritional Assessment (MNA) in the SR group was significantly higher than that of the control group.

Conclusion

This study confirms the efficacy of SR and Montessori‐based activities for eating difficulty and eating ability. A longitudinal study to follow the long‐term effects of SR and Montessori‐based activities on eating ability and nutritional status is recommended. Copyright © 2010 John Wiley & Sons, Ltd.

     

Comparison of Partial (.6 mg/kg) versus Full‐Dose (.9 mg/kg) Intravenous Recombinant Tissue Plasminogen Activator Followed by Endovascular Treatment for Acute Ischemic Stroke: A Meta‐Analysis

ABSTRACT

BACKGROUND

In the treatment of acute ischemic stroke, intravenous (IV) recombinant tissue plasminogen (rt‐PA) and intraarterial (IA) interventions are often combined. However, the optimal dose of IV rt‐PA preceding endovascular treatment has not been established.

METHODS

Studies that used combined IV and IA thrombolysis were identified from a search of the MEDLINE, PubMed, and Cochrane databases. We compared the rates of angiographic recanalization, symptomatic intracerebral hemorrhage (sICH), and favorable functional outcome between patients who had been treated with .6 mg/kg IV rt‐PA and those who had received .9 mg/kg rt‐PA.

RESULTS

Eleven studies met our criteria. In 7 studies, .6 mg/kg IV rt‐PA had been administered to 317 patients, whereas 140 patients in 4 studies had received .9 mg/kg of IV rt‐PA. The weighted mean of median National Institutes of Health Stroke Scale score at presentation was 18.3 in the .6 mg/kg group (median range 9‐34), and 17.3 in the .9 mg/kg group (median range 4‐39). Patients in the .9 mg/kg group had higher rates of favorable outcome [odds ratio (OR) = 1.60, 95% confidence interval (CI) = (1.07‐2.40), P= .022] and similar rates of sICH [OR = .86 (95% CI .41‐1.83), P= .70]. Depending on the statistics used, the higher angiographic recanalization rate among patients treated with .9 mg/kg was significant (P= .03, events/trial syntax logistic regression) or borderline significant (P= .07, random effects model).

CONCLUSION

Our analysis suggests that using .9 mg/kg IV rt‐PA prior to IA thrombolysis is safe and may be associated with higher recanalization rates and better functional outcome at 3 months.

     

Disorder‐specific dysfunction in right inferior prefrontal cortex during two inhibition tasks in boys with attention‐deficit hyperactivity disorder compared to boys with obsessive–compulsive disorder

Background:

Inhibitory dysfunction is a key behavioral and cognitive phenotype of attention‐deficit hyperactivity disorder (ADHD) and obsessive–compulsive disorder (OCD). Both disorders show neuropsychological deficits and fronto‐striatal dysfunction during tasks of motor response inhibition and cognitive flexibility. This study investigates differences and commonalities in functional neural networks mediating inhibitory control between adolescents with ADHD and those with OCD to identify disorder‐specific neurofunctional markers that distinguish these two inhibitory disorders.

Methods:

Event‐related fMRI was used to compare brain activation between 20 healthy boys, 18 (Stop task) or 12 boys (Switch task) with ADHD, and 10 boys with OCD during a tracking Stop task that measures inhibition and stopping failure and during a visual–spatial switching task measuring cognitive flexibility.

Results:

Both patient groups shared brain dysfunction compared to healthy controls in right orbitofrontal (successful inhibition) and left dorsolateral prefrontal cortices (failed inhibition). Right inferior prefrontal dysfunction, however, was disorder‐specific to ADHD during both tasks. Left inferior prefrontal dysfunction during the Switch task was significant in children with ADHD relative to controls, but only reached a trend in patients with OCD. Patients with ADHD furthermore showed disorder‐specific dysfunction in left basal ganglia and cingulate gyrus during the Switch task.

Conclusions:

Patients with ADHD compared to those with OCD have both common and distinct dysfunctions during inhibitory control. The most consistently reported functional abnormality in children with ADHD in right inferior prefrontal cortex during inhibitory control appears to be disorder‐specific when compared to patients with OCD and may be a specific neurofunctional biomarker of ADHD. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.

     

Ten‐year follow‐up study of Japanese patients with obsessive–compulsive disorder

Aim

Obsessive–compulsive disorder (OCD) is a well‐known chronic illness. This study retrospectively investigated 10‐year outcomes and associated clinical factors in Japanese OCD patients. We focused on the impact of several sociocultural factors, including medical expenses and insurance systems specific to each country, on the differences or biases in follow‐up procedures of OCD.

Methods

Seventy‐nine patients diagnosed with OCD who received a standardized combination of treatments for 10 continuous years were divided into three groups according to their improvement rates on the Yale–Brown Obsessive–Compulsive Scale after 10 years of treatment.

Results

A survival analysis revealed that the rate of patients achieving full remission increased every year. Following 10 years of treatment, 56% of OCD patients experienced ‘full remission’ for at least 1 year. Consequently, 48% exhibited full remission, and 37% exhibited partial remission at the end‐point of this study. We identified several factors that were predictive of poorer outcomes, including lower Global Assessment of Functioning Scale scores and the presence of hoarding symptoms or involvement behaviors. In addition, improvement rates after 1 year significantly predicted better 10‐year outcomes.

Conclusion

Our findings highlight the transcultural nature of long‐term outcomes of OCD treatment, which appear to be independent of sociocultural differences.

     

Advanced time‐series analysis of MEG data as a method to explore olfactory function in healthy controls and Parkinson's disease patients

Objectives:

To determine whether time‐series analysis of magnetoencephalography (MEG) data is a suitable method to study brain activity related to olfactory information processing, and to detect differences in odor‐induced brain activity between patients with Parkinson's disease (PD) and controls.

Methods:

Whole head 151‐channel MEG recordings were obtained in 21 controls and 20 patients with PD during a 10‐min olfactory stimulus paradigm, consisting of 10 alternating rest‐stimulus cycles (30 s each), using phenylethyl alcohol administered by means of a Burghart olfactometer. Relative spectral power and synchronization likelihood (SL; an unbiased measure of functional connectivity) were calculated for delta, theta, alpha1, alpha2, beta, and gamma frequency bands.

Results:

In controls, olfactory stimulation produced an increase in theta power and a decrease in beta power. In patients with PD, there was a decrease in alpha1 power. No significant interaction between group and condition was found for spectral power. SL analysis revealed a significantly different response to olfactory stimulation in patients with PD compared to controls. In controls, the odor stimulus induced a decrease in local beta band SL. The response in patients with PD involved a decrease in intrahemispheric alpha2 band SL.

Conclusion:

This is the first study to show that time‐series analysis of MEG data, including spectral power and SL, can be used to detect odor‐induced changes in brain activity. In addition, differences in odor‐induced brain activity were found between patients with PD and controls using analysis of SL, but not of spectral power. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.

     

Characteristic Neuroimaging in Patients with Tumefactive Demyelinating Lesions Exceeding 30 mm

ABSTRACT

BACKGROUND AND PURPOSE

Features of tumefactive demyelinating lesion (TDL) on magnetic resonance imaging (MRI) can facilitate the differential diagnosis of TDL and neoplastic lesions, but vary considerably among patients. The larger TDL grows, the more difficult it becomes to differentiate TDL from neoplastic lesions. The purpose of this study was to elucidate typical MRI features in 12 patients with large TDL (>30 mm in diameter).

METHODS

We identified 12 patients with large TDL (six men, six women; age range 17‐64 years, median age 27 years) and studied the clinical histories and the results of laboratory and various radiological studies in these patients. All cases of clinically definite multiple sclerosis were diagnosed in accordance with McDonald's revised criteria.

RESULTS

Common MRI features of large TDLs included variable degrees of mass effect (71%) and edema (100%), a T2 hypointense rim (79%), venular enhancement (57%), and peripheral restriction on diffusion‐weighted images (50%). Ring enhancement (38%), open‐ring enhancement (31%), or decreased N‐acetylaspartate ratios on magnetic resonance spectroscopy (22%) were less frequently observed. Brain angiography demonstrated venous dilatations on and around the TDL.

CONCLUSIONS

The diagnosis of large TDL is challenging. Our findings suggest that multiple venous dilatations on and around TDLs on angiography can facilitate diagnosis.

     

Just‐in‐time response to reward as a function of ADHD symptom severity

Aim

Attention‐deficit hyperactivity disorder (ADHD) neuroimaging studies have identified substantial differences in reward‐related circuits on a trial‐by‐trial basis. However, no research to date has evaluated the effect of motivational context on neural activity in settings with intermittent reward in ADHD. The present study was designed to identify neural processes underlying both immediate effects of reward and sustained effects of reward associated with motivational context in adult ADHD patients.

Methods

We used a functional magnetic resonance imaging paradigm, including a time estimation task with constant versus intermittent reward conditions, in a sample of 21 medication‐naïve adults with combined ADHD and 24 healthy adults.

Results

Although no between‐group neural differences were detected, orbitofrontal activity dropped in association with high ADHD symptom severity during the transition from initial non‐reward context blocks to subsequent reward context blocks. In turn, ADHD symptom severity predicted higher orbitofrontal activity in response to immediate reward versus no reward within reward context blocks.

Conclusion

These results suggest that high ADHD symptom severity scorers adopted a ‘just‐in‐time’ strategy, involving the recruitment of reward processing brain areas in the face of immediate reward rather than a sustained response to motivational context.

     

Correlation study of optimized voxel-based morphometry and (1)H MRS in patients with mesial temporal lobe epilepsy and hippocampal sclerosis

Purpose:

To assess whether structural and metabolic brain abnormalities are correlated in MTLE/HS syndrome.

Methods:

Optimized voxel‐based morphometry (VBM) of gray matter concentration (GMC) and gray matter volume (GMV) and proton magnetic resonance spectroscopy measurements from both‐sided hippocampal and thalamic regions were performed in 20 MTLE/HS patients and 20 sex‐ and age‐matched healthy controls. The local GMC and GMV values were calculated in both the affected and unaffected hippocampi and ipsilateral and contralateral thalami in patients and healthy subjects, and these were compared. VBM variables and NAA, NAA/Cr and NAA/(Cr+Cho) values from the investigated brain regions were correlated.

Results:

(1) Analysis revealed significantly more extensive GMV reduction than GMC reduction in patients' affected hippocampus. In addition, significant GMV reduction was observed in the ipsilateral thalamus in MTLE/HS patients. (2) Significant decreases in all VBM and MRS variables were revealed in the affected hippocampus. Whilst practically normal GMC values were revealed in patients' both‐sided thalamic regions, a significant decrease in local GMV and metabolic measurements were found in the patients' ipsilateral thalamus. (3) Pearson's correlations between structural and metabolic abnormalities were significant for the ipsilateral thalamus only.

Conclusion:

Structural and metabolic abnormalities as detected by optimized voxel‐based morphometry and ¹H MRS in hippocampal and thalamic regions are only partially correlated in MTLE/HS patients. It seems therefore reasonable that both methods reflect different aspects of brain pathology, which, at least to some degree, might be independently ongoing. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.

     

Simultaneous EMG-functional MRI recordings can directly relate hyperkinetic movements to brain activity

Objective:

To apply and validate the use of electromyogram (EMG) recorded during functional magnetic resonance imaging (fMRI) in patients with movement disorders, to directly relate involuntary movements to brain activity.

Methods:

Eight “familial cortical myoclonic tremor with epilepsy” (FCMTE) patients, with tremor‐like cortical myoclonus and cerebellar Purkinje cell degeneration, and nine healthy controls performed hand posture and movement in an on/off fashion (block design). Superfluous movements were quantified as deviations in EMG power, positive and negative, with respect to the average EMG per session. This measure, “residual EMG” (r‐EMG), was derived by Gram–Schmidt orthogonalization. Activation maps resulting from conventional block regressors and novel r‐EMG regressors were compared.

Results:

In healthy participants, the block posture regressor identified mainly cerebellar activity and some activity in other areas belonging to motor circuitry. In FCMTE patients, no cerebellar activity was seen with the block posture regressor, compatible with cerebellar Purkinje cell changes in FCMTE. EMG power showed little variation during posture in healthy controls. Therefore, the r‐EMG regressor was almost constant and revealed no brain activity as expected. In contrast, in FCMTE patients the r‐EMG posture regressor was highly variable due to continuous myoclonic jerks. It identified sensorimotor cortical areas, compatible with cortical hyperexcitability in FCMTE patients.

Conclusion:

Conventional block regressors can be used to identify neuronal circuitry associated with a specific motor task, whereas r‐EMG regressors can help identify brain activation directly related to involuntary movements. Simultaneous EMG‐fMRI is complementary to conventional fMRI and will facilitate studies of hyperkinetic movement disorders. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.

     

The Clinical and Radiological Spectrum of Posterior Reversible Encephalopathy Syndrome: A Retrospective Series of 24 Patients

ABSTRACT

BACKGROUND AND PURPOSE

Some patients with posterior reversible encephalopathy syndrome (PRES) present with atypical clinical and neuroimaging findings. The purpose of this study is to review the clinical and neuroimaging findings in patients diagnosed with PRES.

METHODS

We retrospectively included all patients diagnosed with PRES between January 2005 and March 2009. We reviewed demographic, clinical and laboratory data, neuroimaging findings, and prognosis.

RESULTS

Twenty‐four patients were included with a median age of 19 years. The clinical presentations included seizures (91.7%), headache (83.3%), visual disturbance (62.5%), encephalophathy (29.2%), and paralysis (8.3%). Co‐morbidities included systemic lupus erythematous (29.2%), kidney disease (20.8%), eclampsia (20.8%), renal artery stenosis (12.5%), Takayasu arteritis (4.2%), Sheehan's syndrome (4.2%), allergic purpura (4.2%), and acute intermittent porphyria (4.2%). Acute elevation of blood pressure was found in 22 patients (91.7%). Ten patients (41.7%) used steroids or immunosuppressants, three (12.5%) had acute renal failure before the symptoms. Atypical neuroimaging features included involvement of the frontal lobe (54.2%), basal ganglia (4.2%) or cortex (8.3%), and irreversible lesions (3/18, 16.7%).

CONCLUSIONS

A large proportion of patients with PRES may present with atypical neuroimaging findings. Apart from the known risk factors, such as hypertension, immunosuppressants, and renal failure of various etiologies may be the precipitants of PRES.

     

Depression and anxiety in chronic heart failure and chronic obstructive pulmonary disease: prevalence,relevance, clinical implications and management principles

Objective

To review evidence regarding the prevalence, causation, clinical implications, aspects of healthcare utilisation and management of depression and anxiety in chronic heart failure and chronic obstructive pulmonary disease.

Design

A critical review of the literature (1994–2009).

Findings

The prevalence of depression and anxiety is high in both chronic obstructive pulmonary disease (8–80% depression; 6–74% anxiety) and chronic heart failure (10–60% depression; 11–45% anxiety). However, methodological weaknesses and the use of a wide range of diagnostic tools make it difficult to reach a consensus on rates of prevalence. Co‐morbid depression and anxiety are associated with increased mortality and healthcare utilisation and impact upon functional disability and quality of life. Despite these negative consequences, the identification and management of co‐morbid depression and anxiety in these two diseases is inadequate. There is some evidence for the positive role of pulmonary/cardiac rehabilitation and psychotherapy in the management of co‐morbid depression and anxiety, however, this is insufficient to guide recommendations.

Conclusions

The high prevalence and associated increase in morbidity and mortality justifies future research regarding the management of anxiety and depression in both chronic heart failure and chronic obstructive pulmonary disease. Current evidence suggests that multi‐faceted interventions such as pulmonary and cardiac rehabilitation may offer the best hope for improving outcomes for depression and anxiety. Copyright © 2009 John Wiley & Sons, Ltd.

     

Changes in resting-state brain networks in writer's cramp

Objectives:

Writer's cramp (WC) is characterized by excessive cocontractions of agonist and antagonist hand and forearm muscles during writing. Changes in functional magnetic resonance imaging activation patterns in such conditions can be ambiguous as they might either reflect some aspect of the primary pathophysiological mechanism or, alternatively, may be the result of adaptive actions during task execution. To circumvent this problem, we examined WC patients during rest, i.e., without a task, using independent component analysis (ICA) applied to the blood oxygen level‐dependent time series.

Methods:

Functionally connected brain networks during rest were defined by ICA to assess differences between WC patients (n = 16) and healthy controls (n = 16). Analysis was carried out using FMRIB's Software Library.

Results:

Two functional networks showed between‐group differences, the sensorimotor network and the default‐mode network. In WC patients, the connectivity was reduced in the left postcentral area and increased in basal ganglia in contrast to healthy controls. These changes were not reversed after treatment with botulinum toxin.

Conclusions:

In line with other studies, the results show a dysfunction in cortico‐subcortical circuits in WC involving somatosensory cortex, areas interfacing the sensory and motor systems, and putamen contralateral to symptomatic hand. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.

     

Non‐pharmacological interventions for adults with intellectual disabilities and depression: a systematic review

Background

Although high rates of depression symptoms are reported in adults with intellectual disabilities (IDs), there is a lack of knowledge about non‐pharmacological treatment options for depression in this population. The first research question of this paper is: Which non‐pharmacological interventions have been studied in adults with ID and depression? The second research question is: What were the results of these non‐pharmacological interventions?

Method

Systematic review of the literature with an electronic search in six databases has been completed with hand searches. Preferred Reporting Items for Systematic Reviews and Meta‐analyses guidelines have been followed. Selected studies met predefined inclusion criteria.

Results

Literature search resulted in 4267 papers of which 15 met the inclusion criteria. Five different types of non‐pharmacological interventions have been studied: cognitive behavioural therapy, behavioural therapy, exercise intervention, social problem‐solving skills programme and bright light therapy.

Conclusion

There are only a few studies of good quality evaluating non‐pharmacological interventions for adults with ID and depression. Some of these studies, especially studies on cognitive behavioural therapy, show good results in decreasing depressive symptoms. High‐quality randomised controlled trials evaluating non‐pharmacological interventions with follow‐up are needed.

     

Sparse multiple factor analysis to integrate genetic data,neuroimaging features,and attention‐deficit/hyperactivity disorder domains

Objectives

We proposed the application of a multivariate cross‐sectional framework based on a combination of a variable selection method and a multiple factor analysis (MFA) in order to identify complex meaningful biological signals related to attention‐deficit/hyperactivity disorder (ADHD) symptoms and hyperactivity/inattention domains.

Methods

The study included 135 children from the general population with genomic and neuroimaging data. ADHD symptoms were assessed using a questionnaire based on ADHD‐DSM‐IV criteria. In all analyses, the raw sum scores of the hyperactivity and inattention domains and total ADHD were used. The analytical framework comprised two steps. First, zero‐inflated negative binomial linear model via penalized maximum likelihood (LASSO‐ZINB) was performed. Second, the most predictive features obtained with LASSO‐ZINB were used as input for the MFA.

Results

We observed significant relationships between ADHD symptoms and hyperactivity and inattention domains with white matter, gray matter regions, and cerebellum, as well as with loci within chromosome 1.

Conclusions

Multivariate methods can be used to advance the neurobiological characterization of complex diseases, improving the statistical power with respect to univariate methods, allowing the identification of meaningful biological signals in Imaging Genetic studies.

     

An open‐label extension long‐term study of the safety and efficacy of aripiprazole for irritability in children and adolescents with autistic disorder in Japan

Aim

The purpose of this study was to evaluate the long‐term safety and efficacy of aripiprazole in treating irritability in pediatric patients (6–17 years) with autistic disorder (AD) in Japan.

Methods

In this open‐label extension study, patients who had completed a previous randomized, double‐blind, placebo‐controlled 8‐week study were enrolled and were flexibly dosed with aripiprazole (1–15 mg/day) until the new indication of irritability in pediatric autism spectrum disorder was approved in Japan.

Results

Seventy (81%) out of 86 enrolled patients completed week‐48 assessments. The mean duration of treatment was 694.9 days. The mean daily dose of aripiprazole over the treatment period was 7.2 mg and the mean of the final dose was 8.5 mg. The most common treatment‐emergent adverse events (TEAE; ≥20%) included nasopharyngitis, somnolence, influenza, and increased weight. The majority of these TEAE were mild or moderate in severity, and there were no deaths, and no clinically relevant findings in laboratory values except prolactin decrease, vital signs, height, or ECG parameters. At week 48 (observed case), the mean change from baseline in the Irritability subscale score for the Aberrant Behavior Checklist Japanese Version was ?6.3 in prior placebo patients and ?2.6 in prior aripiprazole patients.

Conclusion

Aripiprazole was generally safe, well tolerated, and effective in the long‐term treatment of irritability associated with AD in Japanese pediatric patients.

     

Phasic muscle activity in sleep and clinical features of Parkinson disease

Objective

To determine whether amyloid deposition is associated with impaired neuropsychological (NP) performance and whether cognitive reserve (CR) modifies this association.

Methods

In 66 normal elderly controls and 17 patients with Alzheimer disease (AD), we related brain retention of Pittsburgh Compound B (PiB) to NP performance and evaluated the impact of CR using education and American National Adult Reading Test intelligence quotient as proposed proxies.

Results

We found in the combined sample of subjects that PiB retention in the precuneus was inversely related to NP performance, especially in tests of memory function, but also in tests of working memory, semantic processing, language, and visuospatial perception. CR significantly modified the relationship, such that at progressively higher levels of CR, increased amyloid deposition was less or not at all associated with poorer neuropsychological performance. In a subsample of normal controls, both the main effect of amyloid deposition of worse memory performance and the interaction with CR were replicated using a particularly challenging memory test.

Interpretation

Amyloid deposition is associated with lower cognitive performance both in AD patients and in the normal elderly, but the association is modified by CR, suggesting that CR may be protective against amyloid‐related cognitive impairment. ANN NEUROL 2010;67:353–364

     

Axonal pathways linked to therapeutic and nontherapeutic outcomes during psychiatric deep brain stimulation

Objective:

The underlying hypothesis of our work is that specific clinical neuropsychiatric benefits can be achieved by selective activation of specific axonal pathways during deep brain stimulation (DBS). As such, the goal of this study was to develop a method for identifying axonal pathways whose activation is most likely necessary for achieving therapeutic benefits during DBS.

Experimental design:

Our approach combined clinical data, diffusion tensor tractography, and computer models of patient‐specific neurostimulation to identify particular axonal pathways activated by DBS and determine their correlations with individual clinical outcome measures. We used this method to evaluate a cohort of seven treatment‐resistant depression patients treated with DBS of the ventral anterior internal capsule and ventral striatum (VC/VS).

Principal observations:

Clinical responders exhibited five axonal pathways that were consistently activated by DBS. All five pathways coursed lateral and medial to the VS or dorsal and lateral to the nucleus accumbens; however, details of their specific trajectories differed. Similarly, one common pathway was identified across nonresponders.

Conclusions:

Our method and preliminary results provide important background for studies aiming to expand scientific characterization of neural circuitry associated with specific psychiatric outcomes from DBS. Furthermore, identification of pathways linked to therapeutic benefit provides opportunities to improve clinical selection of surgical targets and stimulation settings for DBS devices. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.

     

Hemispheric specialization during mental imagery of brisk walking

Objectives:

Brisk walking, a sensitive test to evaluate gait capacity in normal and pathological aging such as parkinsonism, is used as an alternative to classical fitness program for motor rehabilitation and may help to decrease the risk of cognitive deterioration observed with aging. In this study, we aimed to identify brain areas normally involved in its control.

Methods:

We conducted a block‐design blood oxygen level dependent function magnetic resonance imaging (BOLD fMRI) experiment in 18 young healthy individuals trained to imagine themselves in three main situations: brisk walking in a 25‐m‐long corridor, standing or lying. Imagined walking time (IWT) was measured as a control of behavioral performance during fMRI.

Results:

The group mean IWT was not significantly different from the actual walking time measured during a training session prior to the fMRI study. Compared with other experimental conditions, mental imagery (MI) of brisk walking was associated with stronger activity in frontal and parietal regions mainly on the right, and cerebellar hemispheres, mainly on the left. Presumed imagined walking speed (2.3 ± 0.4 m/s) was positively correlated with activity levels in the right dorsolateral prefrontal cortex and posterior parietal lobule along with the vermis and the left cerebellar hemisphere.

Interpretations:

A new finding in this study is that MI of brisk walking in young healthy individuals strongly involves processes lateralized in right fronto‐parietal regions along with left cerebellum. These results show that brisk walking might be a non automatic locomotor activity requiring a high‐level supraspinal control. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.

     

Effect of phase‐encoding direction on group analysis of resting‐state functional magnetic resonance imaging

Aim

Echo‐planar imaging is a common technique used in functional magnetic resonance imaging (fMRI); however, it suffers from image distortion and signal loss because of large susceptibility effects that are related to the phase‐encoding direction of the scan. Despite this relation, the majority of neuroimaging studies has not considered the influence of phase‐encoding direction. Here, we aimed to clarify how phase‐encoding direction can affect the outcome of an fMRI connectivity study of schizophrenia (SCZ).

Methods

Resting‐state fMRI using anterior to posterior (A–P) and posterior to anterior (P–A) directions was used to examine 25 patients with SCZ and 37 matched healthy controls (HC). We conducted a functional connectivity (FC) analysis using independent component analysis and performed three group comparisons: (i) A–P versus P–A (all participants); (ii) SCZ versus HC for the A–P and P–A datasets; and (iii) the interaction between phase‐encoding direction and participant group.

Results

The estimated FC differed between the two phase‐encoding directions in areas that were more extensive than those where signal loss has been reported. Although FC in the SCZ group was lower than that in the HC group for both directions, the A–P and P–A conditions did not exhibit the same specific pattern of differences. Further, we observed an interaction between participant group and the phase‐encoding direction in the left temporoparietal junction and left fusiform gyrus.

Conclusion

Phase‐encoding direction can influence the results of FC studies. Thus, appropriate selection and documentation of phase‐encoding direction will be important in future resting‐state fMRI studies.