Neural systems for speech and song in autism

Despite language disabilities in autism, music abilities are frequently preserved. Paradoxically, brain regions associated with these functions typically overlap, enabling investigation of neural organization supporting speech and song in autism. Neural systems sensitive to speech and song were compared in low-functioning autistic and age-matched control children using passive auditory stimulation during functional magnetic resonance and diffusion tensor imaging. Activation in left inferior frontal gyrus was reduced in autistic children relative to controls during speech stimulation, but was greater than controls during song stimulation. Functional connectivity for song relative to speech was also increased between left inferior frontal gyrus and superior temporal gyrus in autism, and large-scale connectivity showed increased frontal–posterior connections. Although fractional anisotropy of the left arcuate fasciculus was decreased in autistic children relative to controls, structural terminations of the arcuate fasciculus in inferior frontal gyrus were indistinguishable between autistic and control groups. Fractional anisotropy correlated with activity in left inferior frontal gyrus for both speech and song conditions. Together, these findings indicate that in autism, functional systems that process speech and song were more effectively engaged for song than for speech and projections of structural pathways associated with these functions were not distinguishable from controls.

Neural response to eye contact and paroxetine treatment in generalized social anxiety disorder

Generalized social anxiety disorder (GSAD) is characterized by excessive fears of scrutiny and negative evaluation, but neural circuitry related to scrutiny in GSAD has been little studied. In this study, 16 unmedicated adults with GSAD and 16 matched healthy comparison (HC) participants underwent functional magnetic resonance imaging to assess neural response to viewed images of faces simulating movement into eye contact versus away from eye contact. GSAD patients were then treated for 8 weeks with paroxetine, and 15 patients were re-imaged. At baseline, GSAD patients had elevated neural response to eye contact in parahippocampal cortex, inferior parietal lobule, supramarginal gyrus, posterior cingulate and middle occipital cortex. During paroxetine treatment, symptomatic improvement was associated with decreased neural response to eye contact in regions including inferior and middle frontal gyri, anterior cingulate, posterior cingulate, precuneus and inferior parietal lobule. Both the magnitude of GSAD symptom reduction with paroxetine treatment and the baseline comparison of GSAD vs. HCs were associated with neural processing of eye contact in distributed networks that included regions involved in self-referential processing. These findings demonstrate that eye contact in GSAD engages neurocircuitry consistent with the heightened self-conscious emotional states known to characterize GSAD patients during scrutiny.

Distinct but overlapping neural networks subserve depression and insecure attachment

Insecure attachment has been linked to depression and to outcome in psychotherapy. The neural mechanisms subserving the relationship between attachment security and depression are not well understood. We have developed a method to examine attachment-related brain activity in depression. Twenty-eight women, half depressed, viewed images of their mother, a female friend, and female strangers during fMRI scanning. The effects of depression and insecure attachment were determined with whole-brain multiple linear regression of blood-oxygen-level-dependent response against subjects' Beck Depression Inventory and Adult Attachment Interview (AAI) coherence of mind scores. Interaction effects were analyzed with ANOVA. Activity associated with depression and with insecure attachment was found in the cortico-striato-thalamic circuits of affect regulation. For early attachment (mother-friend contrast), depression scores correlated with activation of cortical and sub-cortical components of these circuits, while attachment insecurity correlated with sub-cortical activity in the same circuitry. Depression and attachment insecurity correlated with both cortical and sub-cortical activities for mother-stranger, and areas of overlap and of enhancing interactions between depression and insecure attachment were found. For late attachment (friend-stranger contrast), only cortical effects were found. Depression and attachment insecurity may be subserved by similar but distinct components of affect regulating circuits. Their interactions may explain the greater difficulty of treating depression in insecurely attached patients and suggest a contributing role for insecure attachment in depression. Further, differential sub-cortical vs cortical encoding of early vs late attachment suggests a top-down model of late attachment, potentially relevant to psychotherapeutic outcome.

Effects of intensive glucose lowering on brain structure and function in people with type 2 diabetes (ACCORD MIND): a randomised open-label substudy

BACKGROUND

People with type 2 diabetes are at risk of cognitive impairment and brain atrophy. We aimed to compare the effects on cognitive function and brain volume of intensive versus standard glycaemic control.

METHODS

The Memory in Diabetes (MIND) study was done in 52 clinical sites in North America as part of Action to Control Cardiovascular Risk in Diabetes (ACCORD), a double two-by-two factorial parallel group randomised trial. Participants (aged 55-80 years) with type 2 diabetes, high glycated haemoglobin A(1c) (HbA(1c)) concentrations (>7·5%; >58 mmol/mol), and a high risk of cardiovascular events were randomly assigned to receive intensive glycaemic control targeting HbA(1c) to less than 6·0% (42 mmol/mol) or a standard strategy targeting HbA(1c) to 7·0-7·9% (53-63 mmol/mol). Randomisation was via a centralised web-based system and treatment allocation was not masked from clinic staff or participants. We assessed our cognitive primary outcome, the Digit Symbol Substitution Test (DSST) score, at baseline and at 20 and 40 months. We assessed total brain volume (TBV), our primary brain structure outcome, with MRI at baseline and 40 months in a subset of participants. We included all participants with follow-up data in our primary analyses. In February, 2008, raised mortality risk led to the end of the intensive treatment and transition of those participants to standard treatment. We tested our cognitive function hypotheses with a mixed-effects model that incorporated information from both the 20 and 40 month outcome measures. We tested our MRI hypotheses with an ANCOVA model that included intracranial volume and factors used to stratify randomisation. This study is registered with ClinicalTrials.gov, number NCT00182910.

FINDINGS

We consecutively enrolled 2977 patients (mean age 62·5 years; SD 5·8) who had been randomly assigned to treatment groups in the ACCORD study. Our primary cognitive analysis was of patients with a 20-month or 40-month DSST score: 1378 assigned to receive intensive treatment and 1416 assigned to receive standard treatment. Of the 614 patients with a baseline MRI, we included 230 assigned to receive intensive treatment and 273 assigned to receive standard treatment in our primary MRI analysis at 40 months. There was no significant treatment difference in mean 40-month DSST score (difference in mean 0·32, 95% CI -0·28 to 0·91; p=0·2997). The intensive-treatment group had a greater mean TBV than the standard-treatment group (4·62, 2·0 to 7·3; p=0·0007).

INTERPRETATION

Although significant differences in TBV favoured the intensive treatment, cognitive outcomes were not different. Combined with the non-significant effects on other ACCORD outcomes, and increased mortality in participants in the intensive treatment group, our findings do not support the use of intensive therapy to reduce the adverse effects of diabetes on the brain in patients with similar characteristics to those of our participants.

FUNDING

US National Institute on Aging and US National Heart, Lung, and Blood Institute.

Differences in regional brain activation patterns assessed by functional magnetic resonance imaging in patients with systemic lupus erythematosus stratified by disease duration

The mediators of tissue damage in systemic lupus erythematosus (SLE) such as antibodies, cytokines and activated immune cells have direct access to most organs in the body but must penetrate the blood-brain barrier (BBB) to gain access to brain tissue. We hypothesized that compromise of the BBB occurs episodically such that the brain will acquire tissue damage slowly and not at the same rate as other organs. On the basis of these assumptions, we wished to determine if duration of disease correlated with brain injury, as measured with functional magnetic resonance imaging (fMRI), and if this was independent of degree of tissue damage in other organs. We investigated differences in brain activation patterns using fMRI in 13 SLE patients stratified by disease duration of ≤2 years (short-term [ST]) or ≥10 years (long-term [LT]). Two fMRI paradigms were selected to measure working memory and emotional response (fearful faces task). Performance in the working memory task was significantly better in the ST group for one and two shape recall; however, both groups did poorly with three shape recall. Imaging studies demonstrated significantly increased cortical activation in the ST group in regions associated with cognition during the two shape retention phase of the working memory task (P < 0.001) and increased amygdala (P < 0.05) and superior parietal (P < 0.01) activation in response to the fearful faces paradigm. In conclusion, analysis of activation patterns stratified by performance accuracy, differences in co-morbid disease, corticosteroid doses or disease activity suggests that these observed differences are attributable to SLE effects on the central nervous system exclusive of vascular disease or other confounding influences. Our hypothesis is further supported by the lack of correlation between regional brain abnormalities on fMRI and the Systemic Lupus International Collaborating Clinics (SLICC) damage index.

Multiple Sclerosis Severity Scale and whole-brain N-acetylaspartate concentration for patients' assessment

BACKGROUND

The ability to predict the course of multiple sclerosis (MS) is highly desirable but lacking.

OBJECTIVE

To test whether the MS Severity Scale (MSSS) and global neuronal viability, assessed through the quantification of the whole-brain N-acetylaspartate concentration (WBNAA), concur or complement the assessment of individual patients' disease course.

METHODS

The MSSS and average WBNAA loss rate (ΔWBNAA, extrapolated based on one current measurement and the assumption that at disease onset neural sparing was similar to healthy controls, obtained with proton magnetic resonance (MR) spectroscopy and magnetic resonance imaging (MRI)) from 61 patients with MS (18 male and 43 female) with long disease duration (15 years or more) were retrospectively examined. Some 27 patients exhibited a 'benign' disease course, characterized by an Expanded Disability Status Scale score (EDSS) of 3.0 or less, and 34 were 'non-benign': EDSS score higher than 3.0.

RESULTS

The two cohorts were indistinguishable in age and disease duration. Benign patients' EDSS and MSSS (2.1 ± 0.7, 1.15 ± 0.60) were significantly lower than non-benign (4.6 ± 1.0, 3.6 ± 1.2; both p < 10(-4)). Their respective average ΔWBNAA, 0.10 ± 0.16 and 0.11 ± 0.12 mM/year, however, were not significantly different (p > 0.7). While MSSS is both sensitive to (92.6%) and specific for (97.0%) benign MS, ΔWBNAA is only sensitive (92.6%) but not specific (2.9%).

CONCLUSION

Since the WBNAA loss rate is similar in both phenotypes, the only difference between them is their clinical classification, characterized by MSSS and EDSS. This may indicate that 'benign' MS probably reflects fortuitous sparing of clinically eloquent brain regions and better utilization of brain plasticity.

Brain tissue volume changes following weight gain in adults with anorexia nervosa

OBJECTIVE

To measure brain volume deficits among underweight patients with anorexia nervosa (AN) compared to control participants and evaluate the reversibility of these deficits with short-term weight restoration.

METHOD

Brain volume changes in gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) were examined in 32 adult women with AN and compared to 21, age and body mass index-range matched control women.

RESULTS

Patients with AN had a significant increase in GM (p = .006, η(2) = 0.14) and WM volume (p = .001, η(2) = 0.19) following weight restoration. Patients on average had lower levels of GM at low weight (647.63 ± 62.07 ml) compared to controls (679.93 ± 53.31 ml), which increased with weight restoration (662.64 ± 69.71 ml), but did not fully normalize.

DISCUSSION

This study suggests that underweight adult patients with AN have reduced GM and WM volumes that increase with short-term weight restoration.

The dorsal medial frontal cortex is sensitive to time on task, not response conflict or error likelihood

The dorsal medial frontal cortex (dMFC) is highly active during choice behavior. Though many models have been proposed to explain dMFC function, the conflict monitoring model is the most influential. It posits that dMFC is primarily involved in detecting interference between competing responses thus signaling the need for control. It accurately predicts increased neural activity and response time (RT) for incompatible (high-interference) vs. compatible (low-interference) decisions. However, it has been shown that neural activity can increase with time on task, even when no decisions are made. Thus, the greater dMFC activity on incompatible trials may stem from longer RTs rather than response conflict. This study shows that (1) the conflict monitoring model fails to predict the relationship between error likelihood and RT, and (2) the dMFC activity is not sensitive to congruency, error likelihood, or response conflict, but is monotonically related to time on task.

A network approach to assessing cognition in disorders of consciousness

OBJECTIVE

Conventional assessments of consciousness rely on motor responses to indicate awareness. However, overt behaviors may be absent or ambiguous in patients with disorders of consciousness (DOC) resulting in underrating capacity for cognition. fMRI during a silent picture-naming task was evaluated as an indicator of command following when conventional methods are not sufficient.

METHODS

A total of 10 patients with and without conventional evidence of awareness, who met diagnostic criteria for the minimally conscious state (MCS) (n = 5), vegetative state (VS) (n = 3), emerged from MCS (EMCS) (n = 1), and locked-in syndrome (LIS) (n = 1), participated in this observational fMRI study.

RESULTS

The LIS and EMCS patients engaged a complete network of essential language-related regions during the object-naming task. The MCS and 2 of the VS patients demonstrated both complete and partial preservation of the object-naming system. Patients who engaged a complete network scored highest on the Coma Recovery Scale-Revised.

CONCLUSIONS

This study supports the view that fMRI during object naming can elicit brain activations in patients with DOC similar to those observed in healthy subjects during command following, and patients can be stratified by completeness of the engaged neural system. These results suggest that activity of the language network may serve as an indicator of high-level cognition and possibly volitional processes that cannot be discerned through conventional behavioral assessment alone.

Self-specific priming effect

Priority of the "self" is thought to be evolutionarily advantageous. However, evidence for this priority has been sparse. In this study, subjects performed a gender categorization task on self- and non-self target faces preceded by either congruent (same gender as target) or incongruent (different gender) periliminal (33ms) or subliminal (17ms) primes. We found that subliminal primes induced a priming effect only on self target faces. This discovery of a self-specific priming effect suggests that functional specificity for faces may include timing as well as spatial adaptations.

The role of adipose cell size and adipose tissue insulin sensitivity in the carbohydrate intolerance of human obesity

Glucose metabolism and insulin sensitivity of isolated human adipose tissue was studied as a function of adipose cell size and number. Glucose metabolism by these tissues was closely related to the number of cells in the fragment, irrespective of cell size. Adipose cells of obese individuals metabolized glucose to carbon dioxide and triglyceride at rates similar to adipose cells of nonobese subjects. In contrast, insulin responsiveness of adipose tissue was dependent upon adipose cell size. The larger its adipose cells the less insulin sensitive was the tissue. Thus, adipose tissue of obese subjects, with enlarged cells, showed a diminished response to insulin. After weight loss and reduction in adipose cell size, insulin sensitivity of the adipose tissue of obese patients was restored to normal. When adipose tissue of obese individuals showed impaired responsiveness to insulin, their plasma insulin levels, after oral glucose, were elevated. Weight loss and reduction in adipose cell size restored plasma insulin concentration to normal, concomitant with the return of normal tissue insulin sensitivity.