Global brain asymmetry is increased in schizophrenia and related to avolition.

OBJECTIVE: Schizophrenia may be the result of a failure of the normal lateralization process of the brain. However, whole-brain asymmetry has not been assessed up to date. Here, we propose a novel measure of global brain asymmetry based on the Dice coefficient to quantify similarity between brain hemispheres. METHOD: Global gray and white matter asymmetry was calculated from high-resolution T1 structural images acquired from 24 patients with schizophrenia and 26 healthy controls, age- and sex-matched. Some of the analyses were replicated in a much larger sample (n = 759) obtained from open-access online databases. RESULTS: Patients with schizophrenia had more global gray matter asymmetry than controls. Additionally, increased gray matter asymmetry was associated with avolition, whereas the inverse relationship was found for anxiety at a trend level. These analyses were replicated in a larger sample and confirmed previous results. CONCLUSION: Our findings suggest that global gray matter asymmetry is related to the concept of developmental stability and is a useful indicator of perturbations during neurodevelopment.

Brain activity in well-controlled perinatally HIV-infected young adults: a fMRI pilot study. / Actividad cerebral en jóvenes infectados por el virus de la inmunodeficiencia humana por transmisión vertical: estudio piloto de resonancia magnética funcional.

INTRODUCTION AND AIM: Perinatal transmission of human immunodeficiency virus (PHIV) is considered a chronic disease that has highlighted several cognitive deficits. From birth to early adulthood, cognition is known to play a fundamental role. However, although neurocognitive processes associated with PHIV have been extensively described by psychometric testing, data is scarce on neural activity from functional magnetic resonance imaging (fMRI) which provides in vivo physiological information. SUBJECTS AND METHODS: We studied described impaired cognitive processes using fMRI on a group of PHIV adolescents with good immunovirological indications and healthy matched controls. Psychological status and neurocognitive functions were also assessed. RESULTS: There were no significant differences between HIV+ and HIV- groups, either on neurocognitive testing nor in fMRI activity for phonological fluency tasks. Prolonged duration of cART was positively associated with greater brain activity in left inferior frontal gyrus (LIFG) which could indicate functional compensation. CONCLUSIONS: These results suggest that neural activity through fMRI in PHIV adolescents with good daily functioning and good immunovirological control may be similar to their peers.

TITLE: Actividad cerebral en jóvenes infectados por el virus de la inmunodeficiencia humana por transmisión vertical: estudio piloto de resonancia magnética funcional.Introducción y objetivos. La infección por el virus de la inmunodeficiencia humana de transmisión vertical (VIH-TV) constituye una enfermedad crónica que puede asociar múltiples alteraciones cognitivas que pueden influenciar el desarrollo de estos pacientes desde la infancia a la vida adulta. Sin embargo, aunque las alteraciones neurocognitivas vinculadas al VIH-TV están ampliamente descritas y valoradas mediante pruebas psicométricas, no existen apenas estudios de actividad neuronal medida a través de la resonancia magnética funcional (RMf). Sujetos y métodos. Analizar la utilidad de la RMf a través de la realización de tareas motoras y de fluidez verbal en un grupo de adolescentes y jóvenes con VIH-TV con buen control inmunovirológico y compararlo con un grupo control negativo de características similares. Se evaluaron también alteraciones psicológicas y funciones neurocognitivas. Resultados. No se encontraron diferencias significativas entre el grupo VIH+ y el grupo control para las tareas ejecutadas durante la RMf ni en la evaluación neurocognitiva. Un mayor tiempo de terapia combinada antirretroviral se asoció de forma directa con una mayor actividad en el giro frontal inferior izquierdo, lo cual podría indicar una posible compensación funcional. Conclusiones. Estos resultados sugieren que la actividad neuronal medida a través de la RMf en adolescentes con VIH-TV y buen control inmunovirológico es similar a la de sus pares.

Decreased processing speed might account for working memory span deficit in schizophrenia, and might mediate the associations between working memory span and clinical symptoms.

OBJECTIVE: Verbal working memory span is decreased in patients with schizophrenia, and this might contribute to impairment in higher cognitive functions as well as to the formation of certain clinical symptoms. Processing speed has been identified as a crucial factor in cognitive efficiency in this population. We tested the hypothesis that decreased processing speed underlies the verbal working memory deficit in patients and mediates the associations between working memory span and clinical symptoms. METHOD: Forty-nine schizophrenia inpatients recruited from units for chronic and acute patients, and forty-five healthy participants, were involved in the study. Verbal working memory span was assessed by means of the letter-number span. The Digit Copy test was used to assess motor speed, and the Digit Symbol Substitution Test to assess cognitive speed. RESULTS: The working memory span was significantly impaired in patients (F(1,90)=4.6, P<0.05). However, the group difference was eliminated when either the motor or the cognitive speed measure was controlled (F(1,89)=0.03, P=0.86, and F(1,89)=0.03, P=0.88). In the patient group, working memory span was significantly correlated with negative symptoms (r=-0.52, P<0.0001) and thought disorganisation (r=-0.34, P<0.025) scores. Regression analyses showed that the association with negative symptoms was no longer significant when the motor speed measure was controlled (ß=-0.12, P=0.20), while the association with thought disorganisation was no longer significant when the cognitive speed measure was controlled (ß=-0.10, P=0.26). CONCLUSIONS: Decrement in motor and cognitive speed plays a significant role in both the verbal working memory impairment observed in patients and the associations between verbal working memory impairment and clinical symptoms.

Natural quintessence with gauge coupling unification.

We show that a positive accelerating universe can be obtained simply by the dynamics of a non-Abelian gauge group. The condensates of the chiral fields obtain a negative power potential below the condensation scale Lambda(c) and allow for a quintessence interpretation of these fields. The only free parameters are N(c), N(f), and the number of dynamically gauge singlet bilinear fields straight phi generated below Lambda(c). We show that it is possible to have unification of all coupling constants, while having an acceptable phenomenology of straight phi as quintessance, without any fine-tuning of the initial conditions. The coincidence problem is not solved but it is put at the same level as that of the particle content of the standard model.