Biomedical subjects
Publications and source records attributed to T Ortiz.
Traditionally assessment of cognitive function has not been employed adequately in our medical community. In the last two decades the neuropsychological assessment has experimented an evolution in order to improvement in specificity and sensitivity. In this paper we present a compendium of neuropsychological test that could be evaluate cognitive function adequately.
INTRODUCTION: Various factors may contribute to cognitive deterioration in temporal lobe epilepsy, and there is controversy as to which has the greatest effect. PATIENTS AND METHODS: In this study, we establish a comparison between patients with temporal lobe epilepsy controlled by drugs and drug-resistant patients, with the object of discovering the effect of different factors in causing cognitive damage. RESULTS: The persons whose disorder was controlled by pharmacological means had better results in memory and intelligence tests than those with drug-resistance. The latter had alterations of declarative memory for verbal material (left) and for visio-spatial material (right) in delayed free recall tests. Also, the greater proportion of symptomatic epilepsies in the drug-resistant group affected their greater cognitive deterioration. CONCLUSIONS: Our results show that having long-standing epilepsy with great frequency of seizures and symptomatic epilepsy is correlated with cognitive alterations in memory function in temporal lobe epilepsy. Most deterioration is seen in patients with long-standing drug resistant symptomatic left mesial temporal epilepsy.
INTRODUCTION: In Alzheimer s disease, together with cognitive changes (loss of memory, lack of orientation in time and space, difficulty in carrying things out, etc.) non cognitive disorders also occur, seriously disturbing the patient s behavioral and emotional balance. Depression, delirious ideas, hallucinations and behavior changes (habits regarding sex, feeding and movement) are amongst the commonest features of this disease from its earliest stages. Several studies have described how initially the histopathological changes selectively involve different structures of the medial temporal lobe ( entorinal cortex, hippocampal formation, amygdala) and gradually includes neocortical association areas. Thus, the amygdala complex, a structure related to processes of memory and emotional control, is severely affected in this disease from the initial stages. PATIENTS AND METHODS: Therefore, to find any possible relationship between involvement of the amygdala and the psychiatric expression of Alzheimer s type dementia, we did a radiological study, using magnetic resonance, together with a neuropsychological study of a group of 24 persons with Alzheimer s disease who had mild moderate deterioration. Analysis of the amygdala area and the scores on the subtest Alzheimer s Disease Assessment Scale Non cognitive (ADAS NC) were the variables chosen for measurement of the anatomical and psychiatric aspects of the subjects under investigation. RESULTS AND CONCLUSIONS: The results of our study show a close relation between involvement of the amygdala (atrophy) and the presence of neuropsychiatric changes in persons with Alzheimer s disease.
INTRODUCTION: To study working memory function in major depression using identification and memory tests with event-related potentials (ERP). METHODS: We compared behavioral performance and event-related potentials during the processing of the Sternberg working memory task in 26 patients with major depression and 64 healthy matched control subjects. RESULTS: Depressed patients had more errors and had an increase in reaction time that was superior to the control subjects during the memory test of 5 letters presented. The depressive patients showed increased event-related potentials (P300 and N400) between 300-700 milliseconds registered in Pz. The prolonged positive activity in the patients ERPs suggests specific deficit in cortical activity and the large prolonged negativity activity in the patients' ERPs suggests abnormal activation of additional neuronal assemblies than those normally participating in the memory task. These data could reflect either compensatory mechanisms of dysfunction of inhibitory systems. CONCLUSIONS: This study provides objective evidence that major depression significantly affects working memory. The ERP changes in depression could be accounted for by cortical activity dysfunction of the central executive control of working memory.
OBJECTIVE: We review the main aspects of functional recovery after brain injury as well as neuroimaging characteristics that make it relevant and useful to assess these changes. We also review some issues regarding recovery of motor and sensory functions, language and visuo spatial processes, and we discuss the methods used in this field, the difficulties found, and future implications. DEVELOPMENT: One of the main aspects in the study of the brain is the capacity to reorganize different functions in order to compensate for the deficits after a lesion in the central nervous system. The study of these adaptive processes is important in a clinical field as well as for basic research, as it is a clear example of brain plasticity. All the findings show how the study of the plastic phenomena or functional reorganization will allow us to better know how the brain works after a lesion. CONCLUSION: The use and combination of the new functional neuroimaging techniques gives the opportunity to register the reorganization of the brain with a high temporal and spatial resolution. It will give also an objective measure to assess the effectiveness of the rehabilitation programs. It will allow to identify different variables related to rehabilitation outcome and will guide effectively the selection of different rehabilitation approaches.
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INTRODUCTION AND DEVELOPMENT: Frontal lobe, more specifically prefrontal cortex, is one of the brain regions that undergoes more protracted ongoing development. The wider the developmental window of one brain structure, the more vulnerable the functions related to it. Hence, executive functions, which are mediated by prefrontal networks, seems to be specially vulnerable during childhood. Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders. Functional neuroimaging techniques have shown a dysfunction in a fronto-striatal network in this disorder, that is likely subserving deficits in executive processes, such as in response inhibition. DISCUSSION: This review focuses on contributions of neuroimaging techniques, with high spatial (SPECT, PET and fMRI), temporal (ERP) and spatio-temporal (MEG) resolution, to the neurofunctionality of ADHD.
Development of executive functions (EF) during childhood and adolescence is closely related to frontal lobe maturation and its connections with other cortical and subcortical structures. The main maturative processes are myelination and synaptic pruning, both of which work on the brain following a hierarchical model. Different studies agree with the fact that EF emerge at the age of 6 years. However, these studies have used complex neuropsychological tests, which require appropriate functioning of several cognitive functions. This is why differential development of different EF components cannot be observed. To do so, other studies have designed simpler tasks, which only need active maintenance of information and inhibition, both basic functions for the appropriate execution of more complex EF tasks. When these simple tasks are used, an early appearance of EF can already be noticed at the age of 12 months, and there are important advances between the third and fifth year. Consequently, the idea of the frontal lobe being "functionally silent" until adolescence seems definitively discarded.
INTRODUCTION: This paper reports the usefulness of magnetoencephalography (MEG) in the anatomical localization of the onset and spread of seizures. CASE REPORT: In a 34-year-old male patient who suffered from drug-resistant complex partial seizures (sometimes generalized) with loss of awareness, magnetic resonance imaging revealed a probable left frontobasal cortical dysplasia. Ictal scalp electroencephalogram showed left frontotemporal theta waves. Electrocorticography (ECoG) registered interictal polyspike discharges and located the seizure onset in the lateral orbital side of the left frontal lobe. Three seizures were registered by MEG, clinically similar to the ones usually experienced by the patient. MEG ictal spike dipole location showed seizure onset coming from the left inferior frontal gyrus (as the ECoG), spreading on to other frontal areas, insula and temporal lobe, all in the left hemisphere. CONCLUSION: MEG may be considered as a useful diagnosis modality in the study of partial seizure physiopathology as well as in its presurgical evaluation.
Visual evoked responses were recorded in response to a series of consonants and non-linguistic signs randomly presented. We compared, with a sample of 16 young volunteers, P300 and N400 latency and amplitude in order to detect possible asymmetries. Results in amplitude showed a significant asymmetry within right hemisphere, both in P300 and N400 components. Latency results failed to present any significant difference during the discrimination of consonants, while non-linguistic signs discrimination reflect an asymmetrical tendency in P300 component.
Electroencephalographic recording was performed in 11 patients graded by the Silva's Method under basal conditions and under "dynamic meditation". Previous papers showed changes in the EEG of subjects who practice diverse methods of meditation and relaxation. Our results reveal a significant increase in the mean values of the alpha potency in occipital -01, 02- and temporal--T3, T4--areas, while subjects were practicing dynamic meditation.
Event related Potentials, which seem to be an objective parameter reflecting cognitive functions, have been examined in depression. To evaluate the influence of visual and auditory stimuli on the P300 latency we studied 42 patients with major depression and 21 normal subjects. The experimental tasks applied were first a series of 300 auditory stimuli [255 (85%) were tones of 1000 Hz, and considered the frequent stimulus, whereas 45 (15%) were tones of 2000 Hz and referred to as the rare stimulus and second a series of 300 visual stimuli 255 (85%) were black circles on a white background, and considered the frequent stimulus, 9 cm diameter, 200 ms duration whereas 45 (15%) were back squares on a white background and referred to as the rare stimulus, 9 cm diameter, 200 ms duration] in the center of a computer screen. The results shown an increase of P300 latency in depressive patients during auditory and visual tasks. Non differences were found in reaction time to visual or auditory stimuli. These results are consistent with an impairment in brain function in depressive patients that is associated with cortical hypoactivity and deficits in perceptive, auditory or visual, functions.
The P300 component studies, have been generated discussion about his source, cognitive meaning and clinical applications. Since the first point of view, different structures have been proposed as a probable source of P3a or P3b in oddball and memory task and in scalp and in a intracraneal recordings. There are many papers that lucubrate about cognitive meaning of P300 and the applications of this component in the diagnostic process of psychiatric pathology. We make critic analysis and different points of view about this component.