Search

In the last years, there has been a big effort to identify risk factors for reading difficulties and to develop new methodologies to help struggling readers. It has been shown that early intervention is more successful than late intervention, and that intensive training programs can benefit children with reading difficulties. The aim of our study is to investigate the effectiveness of an intensive computerized phonological training program designed to improve reading performance in a sample of children with reading difficulties at the early stages of their reading learning process. Thirty-two children with reading difficulties were randomly assigned to one of the two intervention groups: RDIR (children with reading difficulties following a computerized intensive remediation strategy) (n = 20) (7.01 ± 0.69 years), focused on training phonemic awareness, decoding and reading fluency through the computational training; and RDOR (children with reading difficulties following an ordinary remediation strategy) (n = 12) (6.92 ± 0.82 years), which consisted of a reinforcement of reading with a traditional training approach at school. Normal readers (NR) were assigned to the control group (n = 24) (7.32 ± 0.66 years). Our results indicate that both the RDIR and RDOR groups showed an increased reading performance after the intervention. However, children in the RDIR group showed a stronger benefit than the children in the RDOR group, whose improvement was weaker. The control group did not show significant changes in reading performance during the same period. In conclusion, results suggest that intensive early intervention based on phonics training is an effective strategy to remediate reading difficulties, and that it can be used at school as the first approach to tackle such difficulties.

The link between literacy difficulties and brain alterations has been described in depth. Resting-state fMRI (rs-fMRI) has been successfully applied to the study of intrinsic functional connectivity (iFc) both in dyslexia and typically developing children. Most related studies have focused on the stages from late childhood into adulthood using a seed to voxel approach. Our study analyzes iFc in an early childhood sample using the multivariate pattern analysis. This facilitates a hypothesis-free analysis and the possible identification of abnormal functional connectivity patterns at a whole brain level. Thirty-four children with literacy difficulties (LD) (7.1 ± 0.69 yr.) and 30 typically developing children (TD) (7.43 ± 0.52 yr.) were selected. Functional brain connectivity was measured using an rs-fMRI acquisition. The LD group showed a higher iFc between the right middle frontal gyrus (rMFG) and the default mode network (DMN) regions, and a lower iFc between the rMFG and both the bilateral insular cortex and the supramarginal gyrus. These results are interpreted as a DMN on/off routine malfunction in the LD group, which suggests an alteration of the task control network regulating DMN activity. In the LD group, the posterior cingulate cortex also showed a lower iFc with both the middle temporal poles and the fusiform gyrus. This could be interpreted as a failure in the integration of information between brain regions that facilitate reading. Our results show that children with literacy difficulties have an altered functional connectivity in their reading and attentional networks at the beginning of the literacy acquisition. Future studies should evaluate whether or not these alterations could indicate a risk of developing dyslexia.

The link between literacy difficulties and brain alterations has been described in depth. Resting-state fMRI (rs-fMRI) has been successfully applied to the study of intrinsic functional connectivity (iFc) both in dyslexia and typically developing children. Most related studies have focused on the stages from late childhood into adulthood using a seed to voxel approach. Our study analyzes iFc in an early childhood sample using the multivariate pattern analysis. This facilitates a hypothesis-free analysis and the possible identification of abnormal functional connectivity patterns at a whole brain level. Thirty-four children with literacy difficulties (LD) (7.1 ± 0.69 yr.) and 30 typically developing children (TD) (7.43 ± 0.52 yr.) were selected. Functional brain connectivity was measured using an rs-fMRI acquisition. The LD group showed a higher iFc between the right middle frontal gyrus (rMFG) and the default mode network (DMN) regions, and a lower iFc between the rMFG and both the bilateral insular cortex and the supramarginal gyrus. These results are interpreted as a DMN on/off routine malfunction in the LD group, which suggests an alteration of the task control network regulating DMN activity. In the LD group, the posterior cingulate cortex also showed a lower iFc with both the middle temporal poles and the fusiform gyrus. This could be interpreted as a failure in the integration of information between brain regions that facilitate reading. Our results show that children with literacy difficulties have an altered functional connectivity in their reading and attentional networks at the beginning of the literacy acquisition. Future studies should evaluate whether or not these alterations could indicate a risk of developing dyslexia.

Complex numerical cognition is a crucial ability in the human brain. Conventional neuroimaging techniques do not differentiate between epiphenomena and neuronal groups critical to numerical cognition. Transcranial magnetic stimulation (TMS) allows defining causal models of the relationships between specific activated or inhibited neural regions and functional changes in cognition. However, there is insufficient knowledge on the differential effects of various TMS protocols and stimulation parameters on numerical cognition. This systematic review aimed to synthesize the evidence that different TMS protocols provide regarding the neural basis of numerical cognition in healthy adults. We included 21 experimental studies in which participants underwent any transcranial magnetic stimulation such as a single pulse TMS, repetitive TMS, and theta-burst stimulation. The primary outcome measures were any change in numerical cognition processes evidenced by numerical or magnitude tasks, measured with any independent variable like reaction times, accuracy, or congruency effects. TMS applied to regions of the parietal cortex and prefrontal cortex has neuromodulatory effects, which translate into measurable behavioral effects affecting cognitive functions related to arithmetic and numerical and magnitude processing. The use of TMS for the study of the neural bases of numerical cognition allows addressing issues such as localization, timing, lateralization and has allowed establishing site-function dissociations and double site-function dissociations. Moreover, this technique is in a moment of expansion due to the growing knowledge of its physiological effects and the enormous potential of combining TMS with other techniques such as electroencephalography, functional magnetic resonance imaging, or near-infrared spectroscopy to reach a more precise brain mapping.

Gifted children learn more rapidly and effectively than others, presumably due to neurophysiological differences that affect efficiency in neuronal communication. Identifying the topological features that support its capabilities is relevant to understanding how the brain structure is related to intelligence. We proposed the analysis of the structural covariance network to assess which organizational patterns are characteristic of gifted children. The graph theory was used to analyse topological properties of structural covariance across a group of gifted children. The analysis was focused on measures of brain network integration, such as, participation coefficient and versatility, which quantifies the strength of specific modular affiliation of each regional node. We found that the gifted group network was more integrated (and less segregated) than the control group network. Brain regional nodes in the gifted group network had higher versatility and participation coefficient, indicating greater inter-modular communication mediated by connector hubs with links to many modules. Connector hubs of the networks of both groups were located mainly in association with neocortical areas (which had thicker cortex), with fewer hubs in primary or secondary neocortical areas (which had thinner cortex), as well as a few connector hubs in limbic cortex and insula. In the group of gifted children, a larger proportion of connector hubs were located in association cortex. In conclusion, gifted children have a more integrated and versatile brain network topology. This is compatible with the global workspace theory and other data linking integrative network topology to cognitive performance.

Although little is known about the combined effects of Schizophrenia (SZ) and Substance Use Dependence (SUD) in neurocognitive functioning, the current literature points out that performance depends on the specific cognitive domains, the age of individuals and the type of substance of abuse. Our aim is to elucidate, in a sample with SZ and/or cocaine dependent individuals in remission for more than 4 months, their performance in attention, verbal memory and speed of processing, taking into account the possible effect of both age and duration of SUD. The total sample consisted of 95 male patients, aged 20 to 60 years, divided in three groups: one group with SZ and cocaine dependence (SZ+), another group with SZ without cocaine dependence (SZ-) and a third group with cocaine dependence without psychiatric comorbidity (COC). Our results show that those SZ+ who were abstinent for more than four months did not differ from their SZ- counterparts in the neuropsychological functioning. Both SZ groups performed significantly worse than the COC group. A negative impact of age on the neuropsychological performance was found in the SZ+ group, suggesting additive later cognitive deficits in SZ+ patients due to the long-term brain damage of SUD.

Objective Although little is known about neurocognition in Dual Diagnosis, it has been suggested that Schizophrenia (SZ) patients with comorbid substance use belong to a subgroup with lower genetic vulnerability to develop SZ and, consequently, they show better executive and social premorbid functioning. The first aim of this study was to assess the executive functioning, and the second one was to explore the effect of age of onset of substance use in neurocognition in SZ patients with cocaine dependence. Methods The total sample consisted of 95 male patients, aged 20 to 60 years, divided in three groups: one group with SZ and cocaine dependence (SZ+; n = 30), another group with SZ without cocaine dependence (SZ−; n = 30), and a control group with cocaine dependence without psychiatric comorbidity (COC; n = 35). Results We found a better executive functioning in both SZ+ and COC than SZ−. We observed a worse performance of SZ+ patients compared with COC in cognitive set-shifting regardless the age of onset of consumption. Conclusions The results agree with the hypothesis of a lower genetic vulnerability in SZ+ patients to develop psychosis compared with SZ−, who develop it without any additional trigger. However, future research is needed to clarify the current knowledge gaps. Copyright © 2012 John Wiley & Sons, Ltd.

Objective To study the effects of consuming caffeine and glucose, alone and combined, on cognitive performance. Methods Seventy-two healthy subjects (36 women; age range 18–25) were tested early in the morning, having fasted overnight. Using a double-blind, randomised design, subjects received one of the following beverages: water (150 ml); water plus 75 mg of caffeine; water plus 75 g of glucose; water plus and 75 mg of caffeine and 75 g of glucose. Attention, manual dexterity, visuo-spatial and frontal functions, memory (immediate, consolidation and working) and subjective state were all assessed. Results The combination of caffeine and glucose had beneficial effects on attention (sequential reaction time tasks) and on learning and consolidation of verbal memory, effects not being observed when either substance was administered alone. Caffeine only showed improvement in simple reaction time and glucose in simple and one sequential reaction time tasks and in the manual dexterity assembly task. Conclusions The results indicate that the synergistic effects of caffeine and glucose can benefit sustained attention and verbal memory, even with adequate levels of activation of the subjects. However, further studies are required, controlling for different levels of cognitive effort and also considering measurements of neural activity. Copyright © 2010 John Wiley & Sons, Ltd.

Two limiting factors of dopamine activity are the catechol-o-methyltransferase (COMT) and the dopamine transporter (DAT), which terminate dopamine activity by degradation and uptake, respectively. Genetic variants of COMT and DAT have been related to the enzymatic activity and protein availability, respectively. The Met allele of the COMT Val108/158 Met polymorphism has been associated to lower enzymatic activity and the 9-repeat allele of the DAT 40 base-pair (bp) variable number of tandem repeat (VNTR) polymorphism has been related to lower protein availability. Genotypes for COMT and DAT were determined in a sample of 75 healthy subjects, who underwent functional magnetic resonance imaging (fMRI) while performing an N-back task. To further assess the effects of the genotypes on cognition, subjects were administered the Wisconsin Card Sorting Test (WCST) and the Continuous Performance Test (CPT). Analysis of fMRI data revealed an additive effect of these two genes on brain activation in an N-back task, with subjects homozygous for the Val and the 9-repeat alleles showing the highest activation for the same level of performance. Moreover, the Val allele was related to higher number of perseverative errors on the WCST and with a higher number of commission errors on the CPT. The 10-repeat allele was associated with faster reaction times but also with a higher number of commission errors. Our results support a role of the COMT Val108/158 Met and the DAT 40 bp VNTR in both brain activation and cognition.

Traumatic brain injury (TBI) causes hippocampal damage. The hippocampus can be macroscopically divided into the head, body and tail, which differ in terms of their sensitivity to excitability and also in terms of their cortical connections. We investigated whether damage also varies according to the hippocampal area involved, and studied the relationship of hippocampal reductions with memory performance. Twenty TBI patients and matched controls were examined. MRI measurements were performed separately for the hippocampal head, body and tail. Memory outcome was measured by Rey's auditory verbal learning test, Rey's complex figure test and a modified version of Warrington's facial recognition memory test. Group comparison showed that patients had bilateral hippocampal atrophy, mainly involving the hippocampal head. Moreover, TBI subjects showed verbal memory deficits which presented slight correlations with left hippocampal head atrophy.

Background and purpose Previous studies have shown the hippocampus and basal ganglia to be highly sensitive to hypoxic-ischemic insult. The authors' aim was to evaluate the long-term effects of perinatal asphyxia (PA) on the hippocampus and caudate nucleus in a group of participants born at term and who met the criteria for hypoxic-ischemic encephalopathy (HIE). Additionally, the authors looked for damage in other brain regions using voxel-based morphometry (VBM). Methods The sample consisted of 13 participants (8 boys and 5 girls) with a mean age at study of 16.23 years (+/- 2.89) with antecedents of perinatal asphyxia, diagnosed as moderate hypoxic-ischemic encephalopathy. A group of 13 healthy adolescents matched for age, sex, educational level, and social background were recruited as a comparison group. MR scans were acquired on a 1.5T Signa (General Electric, Milwaukee, WI) to evaluate hippocampal and caudate volumes and to perform VBM analysis. Finally, Rey's Auditory Verbal Learning Test was administered to evaluate verbal long-term memory. Results HIE participants were found to have bilateral hippocampal atrophy (P = .015) and gray matter damage in temporal and frontal lobes. The caudate nucleus showed no atrophic changes in PA participants, and VBM analysis did not reveal other consistent brain abnormalities. Verbal long-term memory was slightly worse in HIE participants. Conclusions These findings indicate that PA produces hippocampal and other nonspecific long-term damage, which cannot be compensated for by plasticity mechanisms. However, this damage does not preclude normal development and scholarship.

The analysis of fMRI allows mapping the brain and identifying brain regions activated by a particular task. Prior to the analysis, several steps are carried out to prepare the data. One of these is the spatial smoothing whose aim is to eliminate the noise which can cause errors in the analysis. The most common method to perform this is by using a Gaussian filter, in which the extent of smoothing is assumed to be equal across the image. As a result some regions may be under-smoothed, while others may be over-smoothed. Thus, we suggest smoothing the images adaptively using a Wiener filter which allows varying the extent of smoothing according to the changing characteristics of the image. Therefore, we compared the effects of the smoothing with a wiener filter and with a Gaussian Kernel. In general, the results obtained with the adaptive filter were better than those obtained with the Gaussian filter.

Although previous studies have shown that the human attention system is partially affected by chlorpheniramine, the effects of chlorpheniramine on human auditory selective attention have not yet been explored. This study examines the effects of a single dose of 4 mg of dextro-chlorpheniramine on human auditory selective attention by means of the evaluation of the event-related brain potential (ERP) processing negativity (PN). The study sample consisted of 20 healthy male humans, who received either a single 4-mg dose of dextro-chlorpheniramine or a placebo in a double-blind design. The subjects were given a dichotic listening task, in which they were instructed to press a response button upon detecting deviant tones (target) while their ERPs were recorded. In parallel, subjective tests evaluated the daytime sleepiness, overall vigor, and affect of the subjects. Results showed that the auditory selective attention is impaired under the effects of chlorpheniramine, as reflected by an attenuation of PN amplitude and by a decrease of performance in the group of subjects who took a single 4-mg dose of dextro-chlorpheniramine. No subjective change in the daytime sleepiness, overall vigor, or affect of the subjects was observed. This lack of conscious awareness of the side effects may lead to situations of risk in tasks for which auditory information is important, because no subjective indicators of attention impairment are available to the subjects.

The present study investigated the relationship between genetic variation, MRI measurements and neuropsychological function in a sample of 58 elders exhibiting memory decline. In agreement with previous reports, we found that the epsilon4 allele of the apolipoprotein E (APOE) and the D allele of the angiotensin converting enzyme (ACE) polymorphisms negatively modulated the cognitive performance. Further, we found an association between the A allele of the apolipoprotein C1 (APOC1) polymorphism and poorer memory and frontal lobe function. No clear associations emerged between MRI measures of white matter lesions (WML) or hippocampal sulcal cavities (HSC) and the cognitive performance after controlling for age effects. Further, the degree of WML or HSC lesions was in general not predisposed genetically except for the presence of the A allele of the APOC1 polymorphism that was related to a higher severity of HSC scores. Our results suggest that WML or HSC do not represent important brain correlates of genetic influences on cognitive performance in memory impaired subjects.

Introducción. Uno de los paradigmas más utilizados en el estudio de la atención es el Continuous Performance Test (CPT). La versión de pares idénticos (CPT-IP) se ha utilizado ampliamente para evaluar los déficits de atención en los trastornos del neurodesarrollo, neurológicos y psiquiátricos. Sin embargo, la localización de la activación cerebral de las redes atencionales varía significativamente según el diseño de resonancia magnética funcional (RMf) usado. Objetivo. Diseñar una tarea para evaluar la atención sostenida y la memoria de trabajo mediante RMf para proporcionar datos de investigación relacionados con la localización y el papel de estas funciones. Sujetos y métodos. El estudio contó con la participación de 40 estudiantes, todos ellos diestros (50%, mujeres; rango: 18-25 años). La tarea de CPT-IP se diseñó como una tarea de bloques, en la que se combinaban los períodos CPT-IP con los de reposo. Resultados. La tarea de CPT-IP utilizada activa una red formada por regiones frontales, parietales y occipitales, y éstas se relacionan con funciones ejecutivas y atencionales. Conclusiones. La tarea de CPT-IP utilizada en nuestro trabajo proporciona datos normativos en adultos sanos para el estudio del sustrato neural de la atención sostenida y la memoria de trabajo. Estos datos podrían ser útiles para evaluar trastornos que cursan con déficits en memoria de trabajo y en atención sostenida., Introduction. One of the most used paradigms in the study of attention is the Continuous Performance Test (CPT). The identical pairs version (CPT-IP) has been widely used to evaluate attention deficits in developmental, neurological and psychiatric disorders. However, the specific locations and the relative distribution of brain activation in networks identified with functional imaging, varies significantly with differences in task design. Aim. To design a task to evaluate sustained attention using functional magnetic resonance imaging (fMRI), and thus to provide data for research concerned with the role of these functions. Subjects and methods. Forty right-handed, healthy students (50% women; age range: 18-25 years) were recruited. A CPT-IP implemented as a block design was used to assess sustained attention during the fMRI session. Results. The behavioural results from the CPT-IP task showed a good performance in all subjects, higher than 80% of hits. fMRI results showed that the used CPT-IP task activates a network of frontal, parietal and occipital areas, and that these are related to executive and attentional functions. Conclusions. In relation to the use of the CPT to study of attention and working memory, this task provides normative data in healthy adults, and it could be useful to evaluate disorders which have attentional and working memory deficits.

We investigated residual brain damage in subjects who suffered severe traumatic brain injury (TBI) in childhood, and its relationship with declarative memory impairment. Magnetic resonance imaging (MRI) volumetric data and memory performance were compared between 16 adolescents with antecedents of severe TBI and 16 matched normal controls. Volumes of grey matter, white matter, cerebrospinal fluid (CSF), hippocampus, and caudate nuclei were measured. Verbal memory was assessed by the Rey's Auditory Verbal Learning test and visual memory by the Rey's Complex Figure. TBI patients performed significantly worse than controls in both verbal and visual memory. Patients presented decreased white matter volume and increased CSF. The hippocampus was reduced, but not the caudate nuclei. Memory performance correlated with CSF. Plasticity is incomplete for structural and functional deficits in children with TBI. Hippocampal atrophy, white matter loss, and memory impairment remain until adolescence. Memory sequelae are related more to diffuse brain injury, as reflected by MRI findings of increased CSF, than to hippocampal injury.

Caffeine is part of our everyday lives and probably the most widely-used psychoactive substance around the world. Thousands of people use caffeine as a way of getting ready for the day. It is present in coffee as well as in a wide variety of other drinks (i.e. tea, soft drinks). Because caffeine use...

To review the findings about neural correlates of number processing and arithmetic calculation, as well as the neuro-structural and neurofunctional imaging findings in patients with difficulties in this kind of abilities.The parietal lobe and specifically, the horizontal segment of the intraparietal sulcus, has become specialized in the internal representation of quantities, the abstract processing of magnitudes and the relation between them. On the other hand, the angular gyrus takes part in the verbal processing of certain tasks called arithmetical facts (for instance, multiplication tables and additions of small quantities). Prefrontal cortex, posterior part of temporal lobe, cingulate cortex and several subcortical regions are also involved in number processing. Empirical data have provided theoretical and anatomical models for number processing and calculation of which the Triple Code Model is currently the most accepted one. Moreover, implementation of neuroimaging techniques has demonstrated that patients who reported difficulties in numerical tasks show structural and functional involvement of the intraparietal sulcus.Neuroimaging techniques have allowed to specifying the neural basis of number processing and calculation. These findings can increase our knowledge of developmental dyscalculia and it's neuroanatomical and neurofunctional correlates. In the future, imaging and neuropsychological data could lead us to more accurate diagnosis methods and better educational programs, in order to improve numerical abilities of patients affected by dyscalculia.

Objective Caffeine and glucose can have beneficial effects on cognitive performance. However, neural basis of these effects remain unknown. Our objective was to evaluate the effects of caffeine and glucose on sustained attention, using functional magnetic resonance imaging (fMRI). Methods Forty young right-handed, healthy, low caffeine-consuming subjects participated in the study. In a double-blind, randomised design, subjects received one of the following beverages: vehicle (water, 150 ml); vehicle plus 75 g of glucose; vehicle plus 75 mg of caffeine; vehicle plus 75 g of glucose and 75 mg of caffeine. Participants underwent two scanning fMRI sessions (before and 30 min after of the administration of the beverage). A continuous performance test was used to assess sustained attention. Results Participants who received combined caffeine and glucose had similar performance to the others but had a decrease in activation in the bilateral parietal and left prefrontal cortex. Conclusions Since these areas have been related to the sustained attention and working memory processes, results would suggest that combined caffeine and glucose could increase the efficiency of the attentional system. However, more studies using larger samples and different levels of caffeine and glucose are necessary to better understand the combined effects of both substances. Copyright © 2010 John Wiley & Sons, Ltd.

The aim of this study is to present a short version with 56 items (TCI-56), based on the Temperament and Character Inventory revised version (TCI-R). The psychometric properties of the TCI-56 were studied in a sample of 822 university students (526 women). The factorial structure of the inventory was explored using parallel analysis with normalized promax rotation, considering jointly the items of the Temperament dimensions (HA: Harm avoidance, NS: novelty seeking, RD: Reward dependence and PS: Persistence) and the Character dimensions (SD: Self-directedness, C: Cooperativeness and ST: Self-transcendence). The reliability coefficients were adequate, ranging from .69 for NS to .85 for ST, and the factorial matrices showed a dimensional clustering with satisfactory item saturation in the total sample and both genders. Women presented higher values for HA, RD, PS, SD and C, while men had higher values for NS. The TCI-56 could be a useful instrument to assess Cloninger’s model of the 7 dimensions of personality in non-clinical samples, whenever there is an interest to reduce the time needed to respond. Further studies, however, should explore its adequacy in clinical samples, its test–retest reliability, and the convergent or discriminant validity with other measures of personality.

The purpose of the present study was to evaluate functional connectivity of the hippocampus during a fMRI face-name learning task in a group of elders with mild memory impairment on the basis of the presence or absence of the APOE epsilon4 allele. Twelve epsilon4 carriers and 20 non-carriers with mild memory dysfunction and exhibiting equivalent performance in clinical evaluations of global cognitive function and memory were studied. Subjects underwent a fMRI session consisting of a face-name encoding memory task. Following scanning, subjects were asked to pair faces with their corresponding proper name. Functional connectivity of the hippocampus was measured by using coherence analysis to evaluate the activity of brain circuits related to memory encoding processes. In contrast to non-APOE epsilon4 allele bearers, APOE epsilon4 carriers showed enhanced connectivity with the anterior cingulate, inferior parietal/postcentral gyrus region and the caudate nucleus. Enhanced hippocampal connectivity with additional brain regions in APOE epsilon4 allele carriers during the performance of an associative memory task may reveal the existence of additional activity in the cortico-subcortical network engaged during memory encoding in subjects carrying this genetic variant.

Background: The corpus callosum (CC) is a cerebral structure that reflects cognitive status in several neurological pathologies. Visual inspection of MRI has shown that hypoxic-ischemic encephalopathy (HIE) causes callosal damage. Primary objective: To quantify the CC surface in a sample of patients with antecedents of HIE and a group of matched controls. Research design: Comparisons of CC measures among control subjects, mild HIE patients and moderate HIE patients as well as correlates of CC surface and neuropsychological performance. Methods: Twenty-one adolescent patients with childhood antecedents of HIE were compared to 21 controls. ANALYZE software was used to semi-automatically measure the CC area. Main outcomes and results: Patients with moderate HIE showed corpus callosum reduction. The isthmus and genus were the most affected regions. Corpus callosum size correlated with cognitive function. Conclusions: Corpus callosum quantification provides new evidence of subtle residual deficits in subjects ...

It has been suggested that the pathophysiology of panic disorder (PD) may involve abnormalities in several brain structures, including the amygdala. To date, however, no study has used quantitative structural neuroimaging techniques to examine amygdalar anatomy in this disorder. Volumetric magnetic resonance imaging (MRI) studies of the amygdalas, hippocampi, and temporal lobes were conducted in 12 drug-free, symptomatic PD patients (six females and six males), and 12 case-matched healthy comparison subjects. Volumetric MRI data were normalized for brain size. PD patients were found to have smaller left-sided and right-sided amygdalar volumes than controls. No differences were found in either hippocampi or temporal lobes. These findings provide new evidence of changes in amygdalar structure in PD and warrant further anatomical and MRI brain studies of patients with this disorder.

The spatiotemporal dynamics of the cerebral network involved in novelty processing was studied by means of scalp current density (SCD) analysis of the novelty P3 (nP3) event-related brain potential (ERP). ERPs were recorded from 30 scalp electrodes at the occurrence of novel unpredictable environmental sounds during the performance of a visual discrimination task. Increased SCD was observed at left frontotemporal (FT3), bilateral temporoparietal (TP3 and TP4) and prefrontal locations (F8-F4 and F7-F3), suggesting novelty-P3 generators located in the left auditory cortex, and bilaterally in temporoparietal and prefrontal association regions. Additional increased SCD was found at a central location (Cz) and at superior parietal locations (P3-Pz-P4). The SCD of the nP3 was therefore generated at three successive, partially overlapping, stages of neuroelectric activation. At the central location, SCD started to be significant before the onset of the nP3 waveform, contributing solely to its early phase. At temporoparietal and left frontotemporal locations, nP3 electrophysiological activity was characterized by sustained current density, starting at about 210 ms and continuing during the full latency range of the response, including its early and late phases. At its late phase, the nP3 was characterized by sharp phasic current density at prefrontal and superior parietal locations, starting at about 290 ms and vanishing at around 385 ms. Taken together, these results provide the first evidence of the cerebral spatio-temporal dynamics underlying novelty processing.

OBJECTIVE: The authors examined possible cerebral gray matter abnormalities in patients with panic disorder. METHOD: Gray matter concentration in 18 panic disorder outpatients and 18 healthy subjects was compared by using a voxel-based morphometry approach. RESULTS: Gray matter density of the left parahippocampal gyrus was significantly lower in patients with panic disorder compared with healthy subjects. CONCLUSIONS: This result provides further support for the involvement of the parahippocampal area in the pathophysiology of panic disorder.

Objetivo. Revisar los hallazgos existentes sobre el sustrato neural del procesamiento numerico y del calculo, asi como las alteraciones neuroestructurales y neurofuncionales detectadas en los pacientes con trastornos en dichas habilidades. Desarrollo. La participacion del lobulo parietal resulta crucial. En concreto, el segmento horizontal del surco intraparietal se halla especializado en la representacion interna de las cantidades, el procesamiento abstracto de las magnitudes y su relacion. Por su parte, el giro angular participa en el procesamiento verbal de determinadas tareas aritmeticas y permite la resolucion de los �hechos matematicos� (tablas de multiplicacion y adicion de pequenas cantidades). La corteza prefrontal, la parte posterior del lobulo temporal, la corteza cingulada y distintas regiones subcorticales estan tambien implicadas. Estos resultados han permitido elaborar modelos teoricos explicativos del procesamiento numerico y del calculo, siendo el modelo del �triple codigo� el que tiene mas soporte. Por su parte, el estudio mediante tecnicas de neuroimagen ha puesto de manifiesto que los pacientes con dificultades en el procesamiento numerico presentan alteraciones estructurales y funcionales en el surco intraparietal. Conclusiones. Las tecnicas de neuroimagen han permitido delimitar las bases neurales del procesamiento numerico y del calculo. Estos hallazgos son la base sobre la que estudiar las alteraciones cerebrales asociadas a la discalculia, de manera que, en el futuro, la complementacion con los datos neuropsicologicos podria ayudar a mejorar su diagnostico y a disenar programas individualizados de reeducacion orientados a la mejora en las habilidades numericas de estos pacientes.

Introduccion. El dano cerebral difuso (DCD) secundario al traumatismo craneoencefalico (TCE) puede estudiarse a traves de la evaluacion volumetrica de diversas estructuras, entre las cuales destacan el cuerpo calloso, el hipocampo y los ganglios basales. Asimismo, el volumen de liquido cefalorraquideo es tambien una buena medida de perdida de masa encefalica. Objetivo. Evaluar el DCD producido por un TCE cerrado infantil y observar los efectos que este tiene a largo plazo sobre el rendimiento cognitivo general. Pacientes y metodos. Se partio inicialmente de una muestra de 27 pacientes con TCE cerrado infantil, moderado o grave, de la cual se seleccionaron 15 sujetos, por carecer de lesiones focales, o en su caso, que estas fueran inferiores a 2.600 mm3. En los 15 sujetos estudiados se realizo un analisis volumetrico del liquido cefalorraquideo, del cuerpo calloso, del hipocampo y del nucleo caudado y se comparo con un grupo control. Ademas, se evaluo su deterioro cognitivo general mediante test de inteligencia, de memoria, y de la evaluacion de las funciones frontales y motoras. Resultados. Los resultados mostraron que los pacientes con antecedentes de traumatismo presentaban atrofia en todas las estructuras medidas y que la atrofia del cuerpo calloso fue la variable que mejor explicaba el deterioro cognitivo general. Conclusiones. El dano difuso causado por TCE moderado-grave en la infancia persiste a largo plazo y comporta deficit cognitivos; la atrofia del cuerpo calloso es la que mejor predice el deterioro cognitivo general de los afectados, con relacion a otras estructuras indicadoras de DCD

n. Aims. To review the effects of alcohol on the mismatch negativity (MMN) component, to discuss its viability as a vulnerability marker for alcoholism, and to link it with the P300 component. Method. Alcohol alters the P300 and MMN components of auditory evoked potentials. In alcoholism, the alterations observed in the P300 component in risk subjects have been seen as markers of susceptibility to development ofthe illness. In the case of the MMN component, on the other hand, to date its viability as a vulnerability marker has only been evaluated in three studies, with varying results. While two ofthem found no differences, in the third and most recent it was found that risk subjects presented an increase in the amplitude of the MMN, which was interpreted as a reflection of the cortical hyperexcitability suggested by other authors and which was also reflected in the decrease in the P300 amplitude. Conclusions. The results obtained do not enable us to draw conclusions about whether the MMN component is altered in risk subjects for alcoholism. The differences in the studies that have been conducted could be due to the variations in the characteristics of the samples used or of the evaluation of the characteristics of MMN. The analysis of previous work on P300 or MMN suggests that broader, more homogeneous samples should be used in future research and that, in addition to the MMN peak, its mean amplitude in successive intervals, together with its two subcomponents should also be evaluated separately.

Introduction. The antihistamine chlorpheniramine presents multiple adverse side effects on the central nervous system. In earlier work it has been observed that a dose equal to the one used in this study alters the evokedpotentials PN (processing negativity) and MMN (mismatch negativity), which are, respectively, indicators of selective attention and of an automatic mechanism for detecting changes in auditory stimulation. Aims. The aim of the present study was to evaluate the effects of a single 4 mg dose of dexchlorpheniramine on the evoked potential P300, to enable us to better define its effects on the central nervous system. Subjects and methods. Using the double blind procedure, half a sample consisting in 20 subjects was administered 4 mg of dexchlorpheniramine and the other 10 received placebo. 150 minutes after ingestion the potential P300 was recorded using an active oddball paradigm. Likewise, efficiency in detecting target stimuli was also evaluated. Results. Results show that a single 4 mg dose of dexchlorpheniramine does not alter P300 nor efficiency in detecting target stimuli. Conclusions. Results show that the dose used has no effect on voluntary processes involving the categorization oftarget stimuli nor on their detection. However, the alteration of other attentional mechanisms observed in previous work using the same doses suggests that it would be advisable to employ different evoked potential paradigms in the evaluation of the side effects other active principles or psychoactive substances have on auditory attention.

Summary. Objective. The objective of this study is to review the main investigations into the secondary effects of the antihistamine chlorpheniramine on the central nervous system (CNS). Development. The antagonists of the H1 receptors of histamine, usually used in the treatment of symptoms of allergy or the common cold, have many adverse effects on the CNS. They cause day time drowsiness, cause poorer performance of tasks involving visuo-motor coordination and make it more difficult to detect ‘target’ auditory stimuli in tasks involving sustained concentration. When using evoked potentials (EP) it has been observed that they alter the system for maintaining auditory attention. They cause increased P300 latency, an EP related to the voluntary ability to discriminate between relevant stimuli, a reduction in the amplitude of mismatch negativity (MMN), an EP which is seen as a preattention mechanism for automatic detection of environmental acoustic changes and alters selective attention capacity, reflected by a reduction in the amplitude of processing negativity (PN). Conclusions. These studies show that chlorpheniramine has major adverse effects on the CNS, and the patient may not be subjectively aware of this (e.g. selective attention). This means that in certain situations it is a dangerous substance. The characteristics of these adverse effects should lead to a review of the prescription of chlorpheniramine, and stimulate the search for other substances with similar therapeutic actions but fewer side effects on the CNS. [REV NEUROL 2002; 34: 1178-82]

INTRODUCTION AND OBJECTIVES The hippocampus and the striatum have been proposed as respectively cerebral substrates of declarative and procedural memory. Both structures are vulnerable to traumatic brain injury. Although declarative and procedural memory have been reported to be impaired in traumatic brain injury (TBI), volumetric measures have so far failed to associate this impairment with atrophy of hippocampal and striatal structures. In our study, we investigated the profile of declarative and procedural memory in children who suffered from moderate to severe traumatic brain injury during childhood (injury test interval: 9.42+/-1.98 years). PATIENTS AND METHODS Nineteen patients and matched controls were evaluated on tests of declarative memory and motor learning. Results showed that TBI subjects exhibit poorer performance in both tasks. Moreover, structural magnetic resonance images were obtained from TBI subjects. In order to relate neuropsychological performance with hippocampal and neostriatal volumetric data, correlation analyses were performed. RESULTS Significant positive correlations were obtained between hippocampal volume and memory for objects. Striatal volume correlated positively with motor learning and with verbal memory. CONCLUSIONS It thus seems that plasticity does not completely compensate for the memory deficits resultant from neural loss in the immature brain.

Previous research has shown that polymorphisms of the apolipoproteins E ( APOE) and APOC1 represent genetic risk factors for dementia and for cognitive impairment in the elderly. The brain mechanisms by which these genetic variations affect behavior or clinical severity are poorly understood. We studied the effect of APOE and APOC1 genes on magnetic resonance imaging measures in a sample of 50 subjects with age-associated memory impairment. The APOE E4 allele was associated with reduced left hippocampal volumes and APOE*E3 status was associated with greater frontal lobe white matter volumes. However, no APOE effects were observed when analyses accounted for other potential confounding variables. The effects of APOC1 on hippocampal volumes appeared to be more robust than those of the APOE polymorphism. However, no modulatory effects on brain morphology outside the medial temporal lobe region were observed when demographic variables, clinical status, and other anatomical brain measurements were taken into consideration. Our results suggest that the role of the APOC1 polymorphism in brain morphology of the cognitively impaired elderly should be examined in further studies.