Biomedical subjects

T Ortiz

Publications and source records attributed to T Ortiz.

At least 19 recordsLinked to original sources

PubMed2006

Effects of cholinergic drugs and cognitive training on dementia: 2-year follow-up.

Several studies have shown that pharmacological and cognitive treatments for Alzheimers's disease improve cognitive function for short periods, but fewer studies have evaluated the efficacy of those treatments for longer (2-year) periods. An initial sample of 68 subjects with mild Alzheimer's disease underwent clinical and cognitive evaluation. After evaluation, subjects were assigned to four different groups and participated in a 2-year follow-up study. Group 1 (n = 14) received combined drug and cognitive stimulation, group 2 (n = 20) received only drug treatment, group 3 (n = 14) received only cognitive stimulation, and group 4 (n = 30) received no treatment at all. Results confirmed previous investigation, cognitive and combined stimulation improved patients' performance throughout the 1st year; however, all groups deteriorated gradually throughout the 2nd year of treatment. According to this evidence, it can be concluded that we cannot stop cognitive deterioration after 2 years of treatment, although deterioration is greater and its progress faster in patients not receiving any treatment at all.

Aged↗

PubMed2006

[A comparative study of pragmatic language disorders and autism spectrum disorders using magnetoencephalography].

INTRODUCTION: Pragmatics refers to the social use of language; its precursors are already present during the process of maturing, during the preverbal stage, and become manifest when the child starts to point and to share his or her attention with another person. In cases of specific language impairment (SLI) and autism spectrum disorders (ASD) it can be altered to varying degrees. PATIENTS AND METHODS: Due to the difficulties involved in diagnosis from a clinical point of view, we carried out a study by means of magnetoencephalography (MEG) on a series of 11 patients who had SLI and another series of 9 patients with ASD, in order to determine whether MEG is capable of distinguishing these diagnoses. RESULTS: Patients with SLI displayed pathological activity in the frontal and middle temporal regions of both hemispheres. Patients with ASD showed pathological activity in the perisylvian area. Expressive-receptive SLI with pragmatic language disorder showed pathological activity that was similar to that seen in autism. CONCLUSION: MEG can be used to distinguish between SLI and ASD by studying the epileptiform activity that occurs in pervasive developmental disorders. MEG helps us to understand the continuum that exists between SLI or expressive-receptive SLI and autism.

Autistic Disorder↗

PubMed2006

[The neurobiological foundations of learning disabilities].

INTRODUCTION: Learning disabilities constitute a heterogeneous group of disorders that involve significant alterations in different cognitive domains (acquisition and use of language, reasoning, mathematical skills, visuospatial abilities, and so forth) that are not accounted for by a low level of intelligence, inadequate sociocultural development or lack of academic opportunities. They result from an alteration in basic psychological processes, developmentally linked to an alteration in the central nervous system. Current functional neuroimaging techniques have made it possible to develop a new type of approach to the neurofunctional foundations underlying these disorders, especially with regard to difficulties in the realm of reading/ writing (developmental dyslexia) and attention deficit hyperactivity disorder (ADHD), which have their highest incidence among the infantile population of school-age children. DEVELOPMENT: Neuroimaging studies have revealed a pattern of atypical activity in both kinds of disorders. In the case of dyslexia, alterations have been observed in the perisylvian circuits that underlie the mechanisms involved in reading skills. Studies into ADHD suggest a fronto-striatal dysfunction linked to the difficulties encountered to achieve inhibitory control, as well as alterations in the inferior parietal and posterior temporal cortex. CONCLUSIONS: Functional neuroimaging studies have shown that the clinical manifestations of these disorders are not only due to a dysfunction in specific areas of the brain, but also to alterations in the pattern of connectivity.

Child↗

PubMed2006

Paroxysmal MEG activity in obsessive compulsive patients without SSRIs therapy.

We describe a fronto-temporal paroxysmal rhythmic activity registered by magnetoencephalography (MEG) in two patients with obsessive compulsive disorder (OCD) without SSRIs treatment. The localization of the activity involves cingulate cortex and frontal areas. We think that these MEG findings are related to the disease itself, rather than representing pharmacological SSRIs effect.

Adolescent↗

PubMed2005

Noradrenaline transporter and its turnover rate are decreased in blood lymphocytes of patients with major depression.

Lymphocytes possess transporters of serotonin and dopamine, and also contain monoamines. The objective of this work was to determine the presence of noradrenaline transporters, the turnover rate of noradrenaline and serotonin in lymphocytes of major depression patients, and to correlate the biochemical parameters with the severity of the disorder. Lymphocytes from peripheral blood were isolated by Ficoll/Hypaque, and noradrenaline transporter was studied by binding of [3H]nisoxetine: control group (29, age 31.52+/-1.08, 7 men) and major depression patients (35, age 36.68+/-1.69, 6 men), Hospital Vargas de Caracas. Diagnostic was done by criteria of the American Psychiatric Association and severity by Hamilton Scale for Depression. Levels of noradrenaline, serotonin, 3-methoxy-4-hydroxyphenylglycol and 5-hydroxyindoleacetic acid were determined by HPLC. Turnover rate was evaluated by the ratios of monoamines and metabolites. Correlations were done between the biochemical parameters and the severity of depression. The score of Hamilton for Depression was 22.77+/-0.51. There was a reduction in the number of transporters in lymphocytes of patients, 0.95+/-0.27 versus 4.06+/-1.67 fmol/10(6) cells. Levels of monoamines and metabolites did not significantly differ between patients and controls. However, there was a higher monoamine/metabolite ratio in lymphocytes of patients, indicating a reduction of metabolic turnover rate. Also there was a relative greater concentration of noradrenaline than serotonin in the lymphocytes of the patients, as indicated by the ratio noradrenaline/serotonin. Noradrenergic and serotonergic turnover is decreased in blood peripheral lymphocytes of major depression patients; the reduction in noradrenaline transporter could be related to changes in intracellular levels, and these modifications could result in functional changes of the immune system.

Adult↗

PubMed2005

Evidence of biochemical and biomagnetic interactions in Alzheimer's disease: an MEG and MR spectroscopy study.

BACKGROUND: Several neuroimaging studies have shown reliable differences between Alzheimer's disease (AD) patients and age-matched controls. However, few studies have demonstrated the interactions between neuroimaging methods for the diagnoses of AD. OBJECTIVE: In this study, we try to elucidate the complementary nature of magnetoencephalography (MEG) and magnetic resonance spectroscopy (MRS) examinations in the assessmentof AD. METHODS: Ten patients fulfilling the NINCDS-ADRDA criteria of probable AD, and 10 elderly individuals with no history of neurological or psychiatric illness serving as age-matched controls participated in the study. All patients and controls received an MRS, MEG and neuropsychological assessment. MEG data were obtained in the context of a working memory task, previously utilized in a similar sample of patients. RESULTS: The AD group showed a reduced number of activity sources over left temporoparietal areas during the late portion of the evoked magnetic field (between 400-800 ms), as well as a bilateral temporoparietal increase in creatine and myoinositol concentrations, and in the myoinositol/N-acetyl-aspartate ratio. The combination of the variables 'number of dipoles during the late portion of the evoked magnetic field' and 'myoinositol/N-acetyl-aspartate ratio' accounted for 65% of the variance of the Mini Mental State Examination scores. CONCLUSIONS: These results highlight the importance of assessing the complex brain pathology underlying AD by utilizing multiple brain examination modalities in a coordinate approach.

Aged↗

PubMed2005

Medial temporal lobe neuromagnetic hypoactivation and risk for developing cognitive decline in elderly population: a 2-year follow-up study.

Cognition declines as a function of age. However, some elders could develop more severe status such as mild cognitive impairment (MCI). The aim of this study was the early detection of neurophysiological patterns of brain activity that may predict the possibility of certain subjects to develop MCI. Brain magnetic activity was recorded from 15 healthy subjects during a memory task by means of magnetoencephalography. None of the participants could be considered as MCI at the time of the first clinical evaluation. After 2-year follow-up, five subjects developed MCI and 10 maintained their cognitive status across time. The subjects who developed cognitive decline showed a lower number of activity sources in the left medial temporal lobe between 400 and 800 ms after stimulus onset, as compared to the non-cognitive decline group. These findings may help with the early identification of elderly subjects at high risk of cognitive decline, allowing the possibility of neuropsychological or pharmaceutical treatment that delay or prevent the progression of the cognitive impairment.

Age Factors↗

PubMed2005

[Functional neuroanatomical correlations of the perisylvian area in autism spectrum disorders].

INTRODUCTION: Autism spectrum disorders cover a continuum of disorders ranging from severe autism to mild autism and Asperger's syndrome. They are considered to be a subgroup of the pervasive development disorders and are characterised by the alteration of three basic areas of behaviour, qualitative alterations in reciprocal social interaction, qualitative alterations in communication and patterns of behaviour, and stereotyped, repetitive and restrictive activities and interests. These alterations are expressed to a greater or lesser degree depending on the level of severity of the disorder and can be detected and quantified by clinical instruments such as the ADI-R (Autism Diagnostic Interview-Revised) and the CARS (Childhood Autism Rating Scale). AIMS. Our aim was to establish a relationship between the specific behavioural characteristics of autism (evaluated by ADI-R and CARS) and brain structures and functions. PATIENTS AND METHODS: The sample was made up of 10 subjects (9 boys and 1 girl) diagnosed with pervasive development disorder. RESULTS: We obtained statistically significant Spearman correlations between the ADI-R item restricted, repetitive and stereotyped behaviour patterns and the area of the right inferior precentral gyrus. A positive correlation was also found between the item for abnormality or apparent deviation in development before the age of 36 months and the right supramarginal gyrus area, while the correlation was negative between the former and the left postcentral gyrus. There was also a significant correlation between the number of perisylvian areas and epileptiform activity and qualitative incapacity in communication on the ADI-R, and some items on the CARS with areas of the perisylvian zone. CONCLUSIONS: Our findings confirm the relation between functional alterations of the different areas that make up the perisylvian region and the distinct behavioural features that define and characterise autism.

Autistic Disorder↗

PubMed2005

[Specific language disorders: their diagnosis, classification and study using magnetoencephalography].

INTRODUCTION: Specific language disorder (SLD) is defined as a disorder in which language is slow and retarded with respect to the patient's chronological age, and which is not related to a sensory-auditory or motor deficit or to a pervasive development disorder; in other words, structural and functional neurological developmental disorders must be excluded. After many studies and attempts to reach an agreement, specific language disorders have been broadly classified into two groups: specific expressive language disorder and specific receptive-expressive language disorder. AIMS: Our objective was to study SLD using magnetoencephalography (MEG) in order to look for epileptiform manifestations in precise language areas. PATIENTS AND METHODS: We studied a sample made up of 11 patients with SLD, one of whom had Landau-Kleffner syndrome and one with cryptogenic-type SLD. The criteria used were age-dependent autism exclusion tests and specific language tests for SLD. The MSI technique was carried out on all the patients, by magnetic resonance and MEG. RESULTS: A characteristic pattern is obtained for SLD in the form of irregular spike and polyspike-wave discharges in bilateral frontal channels. The dipoles were situated mainly in the left perisylvian areas. CONCLUSIONS: The study of specific language disorders using MEG enables us to identify the SLD included in a proposed classification as primary-type specific language disorder, cryptogenic-type specific language disorder and secondary-type type specific language disorder, like Landau-Kleffner syndrome.

Language Disorders↗

PubMed2005

[Recent contributions from magnetoencephalography to the neurobiology of attention-deficit/hyperactivity disorder].

INTRODUCTION AND DEVELOPMENT: Current theories postulate that the core cognitive deficit in attention-deficit/hyperactivity disorder (ADHD) is an executive dysfunction. Neuroimaging studies on the whole have provided both anatomical and functional evidence supporting the fronto-striatal dysfunction hypothesis in ADHD. However, recent neuroimaging studies have found anatomical and functional impairments in posterior cortical regions, such as the inferior parietal and posterior temporal cortices, which have been related to a deficit in selective attention. Event related potential (ERP) studies show that ADHD children have an impairment in early components (within the first 200 ms of processing), such as P1 or N1, both of which are sensitive to selective attention effects. These findings cast doubt regarding the fronto-striatal/executive dysfunction as the core deficit in ADHD. CONCLUSIONS: One of the main objectives of ADHD research is the search for its core cognitive deficit and the neural networks underlying it, because it has important repercussions over ADHD diagnosis and treatment. High temporal resolution techniques, such as ERP or magnetoencephalography may be particularly useful in distinguishing the precise moment of cognitive processing during which the brain activity of children with ADHD begins to be impaired. As a consequence, this may help to elucidate the core cognitive deficit in ADHD.

Attention Deficit Disorder with Hyperactivity↗

PubMed2004

Effects of cholinergic drugs and cognitive training on dementia.

A study was performed on patients with Alzheimer's disease (AD) in order to evaluate the efficacy of a combined treatment (donepezil plus cognitive training) in both cognitive processes and affective states. Eighty-six subjects, 25 men and 61 women, with an average age of 75.58 years, were studied. Almost all the subjects had a basic educational level. Donezepil was administered at a dose of 10 mg daily along with cognitive treatment involving images of everyday life and reminiscent music; the sessions took place on Monday to Friday and lasted three quarters of an hour. The study lasted 12 months. Subjects underwent test-retest with the following tests: Mini-Mental State Examination (MMSE), the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-cog); the Geriatric Depression Scale (GDS) and the overall deterioration scale (FAST). The results showed that subjects receiving the combined treatment had a better response than those who did not receive any cognitive training. These subjects' MMSE score decreased by 3.24 on average. The affective symptomatology of those receiving only drug treatment improved whereas the cognitive processes did not.

Aged↗

PubMed2004

Profiles of brain magnetic activity during a memory task in patients with Alzheimer's disease and in non-demented elderly subjects, with or without depression.

The presence of depression is common among the elderly and it often complicates the early diagnosis of Alzheimer's disease (AD). In this study, we searched for brain activity measures that characterise AD. We compared brain magnetic activity profiles during a memory task, obtained from patients with AD, elderly patients with late onset depression, and age matched volunteers without history of neurological or psychiatric disease. AD patients showed significantly reduced activity in left temporal lobe regions during late portions of the event related magnetic response (400 ms or later after stimulus onset), compared with both groups of patients who did not present with serious cognitive decline. This finding highlights the potential usefulness of MEG protocols supporting the differential diagnosis of AD and major depression related cognitive decline in the elderly.

Age of Onset↗

PubMed2004

[A magnetoencephalographic study of generalised developmental disorders. A new proposal for their classification].

INTRODUCTION: Autistic spectrum disorders (ASD) is a term that is not included in DSM IV or in ICD 10, which are the diagnostic tools most commonly used by clinical professionals but can offer problems in research when it comes to finding homogenous groups. DEVELOPMENT: From a neuropaediatric point of view, there is a need for a classification of the generalised disorders affecting development and for this purpose we used Wing's triad, which defines the continuum of the autistic spectrum, and the information provided by magnetoencephalography (MEG) as grouping elements. Specific generalised developmental disorders were taken as being those syndromes that partially expressed some autistic trait, but with their own personality so that they could be considered to be a specific disorder. ASD were classified as being primary, cryptogenic or secondary. The primary disorders, in turn, express a continuum that ranges from Savant syndrome to Asperger's syndrome and the different degrees of early infantile autism. MEG is a functional neuroimaging technique that has enabled us to back up this classification.

Child Development Disorders, Pervasive↗

PubMed2004

[The neurofunctional foundation of cognitive rigidity in attention deficit hyperactivity disorder: some preliminary findings].

INTRODUCTION: It has been proposed that there is an impairment in cognitive flexibility in children with attention deficit hyperactivity disorder (ADHD). The Wisconsin card sorting test (WCST) is the most widely used neuropsychological test for assessing this process. Previous studies have reported the presence of a subgroup of children with ADHD which has a low cognitive flexibility. In addition this subgroup showed a high resistance to the treatment with stimulant medication. OBJECTIVES: The aim of this study was to examine whether there were different patterns of brain magnetic activity in different subgroups of ADHD, during the performance of a cognitive flexibility task, such as WCST. PATIENTS AND METHODS: We recruited a sample of 18 children, divided into three groups according to DSM IV R diagnostic criteria. Here we present preliminary data based on a subsample of nine children. Brain magnetic activity was registered while the children performed the WCST by means of Magnetoencephalography (MEG). This is a non invasive neuroimaging technique with a high spatio temporal resolution. RESULTS: Preliminary results showed that ADHD mixed group had a higher rate of perseverative responses. In addition, a different pattern of brain magnetic activity was noted in this group, showing less activation in anterior cingulate cortex and dorsolateral prefrontal cortex in the left hemisphere during the first 400 ms. CONCLUSIONS: MEG seems to be an useful tool to describe the brain network that subserves cognitive flexibility in different groups of children. It could have important repercussions in the classification of ADHD, both neuropsychologically and pharmacologically.

Attention Deficit Disorder with Hyperactivity↗

PubMed2003

Do cognitive patterns of brain magnetic activity correlate with hippocampal atrophy in Alzheimer's disease?

BACKGROUND: Many reports support the clinical validity of volumetric MRI measurements in Alzheimer's disease. OBJECTIVE: To integrate functional brain imaging data derived from magnetoencephalography (MEG) and volumetric data in patients with Alzheimer's disease and in age matched controls. METHODS: MEG data were obtained in the context of a probe-letter memory task. Volumetric measurements were obtained for lateral and mesial temporal lobe regions. RESULTS: As expected, Alzheimer's disease patients showed greater hippocampal atrophy than controls bilaterally. MEG derived indices of the degree of activation in left parietal and temporal lobe areas, occurring after 400 ms from stimulus onset, correlated significantly with the relative volume of lateral and mesial temporal regions. In addition, the size of the right hippocampus accounted for a significant portion of the variance in cognitive scores independently of brain activity measures. CONCLUSIONS: These data support the view that there is a relation between hippocampal atrophy and the degree of neurophysiological activity in the left temporal lobe.

Aged↗

PubMed2002

Rejoining of DNA strand breaks by T4 DNA ligase in mammalian cells.

We have tested the ability of T4 DNA ligase to rejoin radiation-induced DNA strand breaks in living hamster cells (CHO-K1, EM9, xrs-5). T4 DNA ligase was introduced into cells by electroporation prior to x-irradiation. Single- and double-strand breaks were measured by the alkaline comet assay technique, and double-strand breaks (DSBs) were evaluated by the pulsed-field gel electrophoresis method. In the comet assay, the three cell lines showed reduced tail moments following pretreatment with T4 DNA ligase, both directly after irradiation and after repair incubation for 4 h. Similarly, the results obtained from pulsed-field gel electrophoresis showed reduced DSB frequencies after pretreatment with T4 DNA ligase. We conclude that exogeneous T4 ligase contributes to rejoining of radiation-induced strand breaks.

Animals↗

PubMed2001

Spatio-temporal patterns of brain magnetic activity during a memory task in Alzheimer's disease.

The brain magnetic activity patterns in a high load probe-letter (targets and distractors) memory task were examined in patients with Alzheimers's disease (AD) and elderly controls. Control subjects showed a higher number of activity sources over the temporal and parietal cortex between 400 and 700 ms after stimulus onset. However, AD patients showed a higher number of sources over the frontal motor areas, including Broca's and the insula. The number of activity sources on the left parietal areas in response to the target stimuli predicted the AD score oncognitive (MMSE, CAMCOG) and functional staging (FAST) scales. These results suggest that a high information load reveals a deficient functioning of phonological store and reduced task-related activity in temporal and parietal areas, manifesting in a rapid information trace decay. The increased levels of activity in motor areas may reflect a compensatory strategy in an attempt to facilitate rehearsal speed.

Aged↗

PubMed2001

Neural processing to visual stimuli in a three-choice reaction-time task.

Some authors have suggested that certain components of the event-related potentials (ERPs) reflect underlying stages in the discrimination process. Previous studies have shown that in an auditive three-choice reaction-time task the discrimination is accomplished as a two-stage process, with the more frequently occurring stimulus discriminated at an earlier point than the rarer stimulus and the subjects could be classified as fast and slow responders in function of their response to the most frequent of the three tones. We continuously recorded the electrocerebral activity (EEG) from the scalp and the electromyographic activity (EMG) from the responding muscles in a visual three-choice reaction-time task in 10 strictly right-handed subjects. EEG and EMG responses were subsequently analyzed off-line by aligning them by the onset of either the stimulus (stimulus-synchronized) or the response (response-synchronized). The results suggest that processes of visual stimuli evaluation and response execution are continuously integrated. The discrimination and response systems to visual stimuli is accomplished as a three-stage process, one to frequent tone, another for rare 1, and the last for rare 2. The subjects were classified as fast and slow responders in function of their response to the most frequent of the three tones.

Adult↗