NURIA ASCENSION PAUL LAPEDRIZA - Academia.edu (original) (raw)
Papers by NURIA ASCENSION PAUL LAPEDRIZA
Traumatic brain injury: Neuropsychological rehabilitation, 2016
Brain Informatics, 2015
Predicting the evolution of individuals is a rather new mining task with applications in medicine... more Predicting the evolution of individuals is a rather new mining task with applications in medicine. Medical researchers are interested in the progression of a disease and/or how do patients evolve or recover when they are subjected to some treatment. In this study, we investigate the problem of patients' evolution on the basis of medical tests before and after treatment after brain trauma: we want to understand to what extend a patient can become similar to a healthy participant. We face two challenges. First, we have less information on healthy participants than on the patients. Second, the values of the medical tests for patients, even after treatment started, remain well-separated from those of healthy people; this is typical for neurodegenerative diseases, but also for further brain impairments. Our approach encompasses methods for modelling patient evolution and for predicting the health improvement of different patients' subpopulations, i.e. prediction of label if they recovered or not. We test our approach on a cohort of patients treated after brain trauma and a corresponding cohort of controls. Keywords Traumatic brain injury Á Label prediction Á Evolution modelling Á Clustering Mathematics Subject Classification MSC code1 Á MSC code2 Á more The dataset used in this work was made available through the cooperation ''Data Mining and Stream Mining for Epidemiological Studies on the Human Brain'' (StreaMED) between the Centre of Biomedical Technology (CTB) of the University Polytecnica de Madrid and the Otto-von-Guericke University Magdeburg.
Alzheimers & Dementia, Jun 1, 2023
Clinical Neurophysiology, 2022
Clinical Neuropsychologist, Jun 28, 2018
Objective: Previous literature has shown that executive functions (EF) are related to performance... more Objective: Previous literature has shown that executive functions (EF) are related to performance in memory tasks. The fact that there are no psychometric tests that evaluate these two constructs simultaneously led a group of researchers to develop the Test of Memory Strategies (TSM). Given the potential importance of this instrument for neuropsychological evaluation, in this study, we aimed to evaluate the psychometric properties of the TMS in Portuguese sample. We also examined the effect of aging by exploring profiles of performance on the TMS, comparing young and elderly healthy subjects. Method: Total of 135 healthy participants were submitted to a neuropsychological assessment and were divided into four age groups: a group of young adults (25-35 years) and three groups of older individuals (aged 60-69 years, 70-79 years, and 80 or more years). Results: Findings supported the reliability of the TMS scores, based on analyses of internal consistency. As expected, factor analysis of the TMS scores revealed that the test yielded two factors, one capturing EF and the other memory. Correlations with classic neuropsychological tests supported convergent and discriminant validity of the TMS scores. The elderly groups presented more difficulties in creating and mobilizing memory strategies when compared with a younger group, after controlling for the influence of education, although both groups presented increases in performance throughout the five TMS subscales. Conclusions: The findings suggest that the TMS is an adequate measure to assess memory and EF, simultaneously, presenting adequate psychometric properties for a Portuguese sample.
Clinical Neurophysiology, Mar 1, 2011
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
Neuropsychology Review, 2005
The first two decades of cognitive neuroimaging research have provided a constant increase of the... more The first two decades of cognitive neuroimaging research have provided a constant increase of the knowledge about the neural organization of cognitive processes. Many cognitive functions (e.g. working memory) can now be associated with particular neural structures, and ongoing research promises to clarify this picture further, providing a new mapping between cognitive and neural function. The main goal of this paper is to outline conceptual issues that are particularly important in the context of imaging changes in neural function through recovery process. This review focuses primarily on studies made in stroke and traumatic brain injury patients, but most of the issues raised here are also relevant to studies using other acquired brain damages. Finally, we summarize a set of methodological issues related to functional neuroimaging that are relevant for the study of neural plasticity and recovery after rehabilitation.
Epilepsy & Behavior, 2009
The risk of cognitive decline after mesial temporal lobe (MTL) resection in the dominant hemisphe... more The risk of cognitive decline after mesial temporal lobe (MTL) resection in the dominant hemisphere for treatment of epilepsy has been assessed with the intracarotid amytal procedure and functional neuroimaging. In this study we used magnetoencephalography (MEG) to analyze memory profiles in patients with left hippocampal sclerosis (HS). Biomagnetic brain activity related to successful memory was compared in nine patients with left HS and nine age-matched controls. Patients manifested a higher number of activity sources over the right inferior parietal lobe in the late portion of the time window, and higher activity in the right than in the left MTL between 400 and 800 ms. This was reinforced by a À0.46 MTL laterality index, which indicates right MTL dominance. Controls showed a higher number of dipoles in the left anterior ventral prefrontal region, between 400 and 600 ms, and in the left MTL across the whole time window. Three patients who underwent a left temporal lobectomy, were seizure free, and who did not exhibit memory impairment after left temporal lobectomy, showed no activity in the left MTL presurgically. These results could support the ability of MEG to describe the time-modulated brain activity related to memory success in patients with epilepsy with left HS.
NeuroImage, 2011
The advent of new signal processing methods, such as non-linear analysis techniques, represents a... more The advent of new signal processing methods, such as non-linear analysis techniques, represents a new perspective which adds further value to brain signals' analysis. Particularly, Lempel-Ziv's Complexity (LZC) has proven to be useful in exploring the complexity of the brain electromagnetic activity. However, an important problem is the lack of knowledge about the physiological determinants of these measures. Although a correlation between complexity and connectivity has been proposed, this hypothesis was never tested in vivo. Thus, the correlation between the microstructure of the anatomic connectivity and the functional complexity of the brain needs to be inspected. In this study we analysed the correlation between LZC and fractional anisotropy (FA), a scalar quantity derived from diffusion tensors that is particularly useful as an estimate of the functional integrity of myelinated axonal fibers, in a group of sixteen healthy adults (all female, mean age 65.56 ± 6.06 years, interval 58-82). Our results showed a positive correlation between FA and LZC scores in regions including clusters in the splenium of the corpus callosum, cingulum, parahipocampal regions and the sagittal stratum. This study supports the notion of a positive correlation between the functional complexity of the brain and the microstructure of its anatomical connectivity. Our investigation proved that a combination of neuroanatomical and neurophysiological techniques may shed some light on the underlying physiological determinants of brain's oscillations.
Actas españolas de psiquiatría
Traditionally assessment of cognitive function has not been employed adequately in our medical co... more 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.
Lecture Notes in Computer Science, 2014
Neuropsychology, 2005
Changes in spatiotemporal profiles of brain magnetic activity were investigated in healthy volunt... more Changes in spatiotemporal profiles of brain magnetic activity were investigated in healthy volunteers as a function of varying demands for phonological storage of spoken pseudowords. Greater activity for the phonological memory task was restricted to the dorsolateral prefrontal cortex (DLPFC) in the left hemisphere. During performance of the memory task, activity was initially found in the left superior temporal gyrus (between 100 and 200 ms), followed by activity in the ventrolateral prefrontal, motor, and premotor cortices (between 200 and 300 ms). Activity in DLPFCs was first observed consistently across participants later, between 300 and 400 ms. The data are consistent with the purported role of posterior temporal cortices in phonological analysis and in the online storage of phonological information, the contribution of ventrolateral and motor processing areas in establishment and short-term maintenance of articulatory representations through rehearsal, and the role of DLPFCs in the executive control of the maintenance operation.
Brain, 2010
Cognitive processes require a functional interaction between specialized multiple, local and remo... more Cognitive processes require a functional interaction between specialized multiple, local and remote brain regions. Although these interactions can be strongly altered by an acquired brain injury, brain plasticity allows network reorganization to be principally responsible for recovery. The present work evaluates the impact of brain injury on functional connectivity patterns. Networks were calculated from resting-state magnetoencephalographic recordings from 15 brain injured patients and 14 healthy controls by means of wavelet coherence in standard frequency bands. We compared the parameters defining the network, such as number and strength of interactions as well as their topology, in controls and patients for two conditions: following a traumatic brain injury and after a rehabilitation treatment. A loss of delta-and theta-based connectivity and conversely an increase in alpha-and beta-band-based connectivity were found. Furthermore, connectivity parameters approached controls in all frequency bands, especially in slow-wave bands. A correlation between network reorganization and cognitive recovery was found: the reduction of delta-band-based connections and the increment of those based on alpha band correlated with Verbal Fluency scores, as well as Perceptual Organization and Working Memory Indexes, respectively. Additionally, changes in connectivity values based on theta and beta bands correlated with the Patient Competency Rating Scale. The current study provides new evidence of the neurophysiological mechanisms underlying neuronal plasticity processes after brain injury, and suggests that these changes are related with observed changes at the behavioural level.
Frontiers in human neuroscience, 2011
Plasticity is the mechanism underlying the brain's potential capability to compensate injury.... more Plasticity is the mechanism underlying the brain's potential capability to compensate injury. Recently several studies have shown how functional connections among the brain areas are severely altered by brain injury and plasticity leading to a reorganization of the networks. This new approach studies the impact of brain injury by means of alteration of functional interactions. The concept of functional connectivity refers to the statistical interdependencies between physiological time series simultaneously recorded in various areas of the brain and it could be an essential tool for brain functional studies, being its deviation from healthy reference an indicator for damage. In this article, we review studies investigating functional connectivity changes after brain injury and subsequent recovery, providing an accessible introduction to common mathematical methods to infer functional connectivity, exploring their capabilities, future perspectives, and clinical uses in brain injur...
Frontiers in Neurology, 2022
BackgroundStroke is the second leading cause of death worldwide and it causes important long-term... more BackgroundStroke is the second leading cause of death worldwide and it causes important long-term cognitive and physical deficits that hamper patients' daily activity. Neuropsychological rehabilitation (NR) has increasingly become more important to recover from cognitive disability and to improve the functionality and quality of life of these patients. Since in most stroke cases, restoration of functional connectivity (FC) precedes or accompanies cognitive and behavioral recovery, understanding the electrophysiological signatures underlying stroke recovery mechanisms is a crucial scientific and clinical goal.MethodsFor this purpose, a longitudinal study was carried out with a sample of 10 stroke patients, who underwent two neuropsychological assessments and two resting-state magnetoencephalographic (MEG) recordings, before and after undergoing a NR program. Moreover, to understand the degree of cognitive and neurophysiological impairment after stroke and the mechanisms of recove...
Traumatic brain injury: Neuropsychological rehabilitation, 2016
Brain Informatics, 2015
Predicting the evolution of individuals is a rather new mining task with applications in medicine... more Predicting the evolution of individuals is a rather new mining task with applications in medicine. Medical researchers are interested in the progression of a disease and/or how do patients evolve or recover when they are subjected to some treatment. In this study, we investigate the problem of patients' evolution on the basis of medical tests before and after treatment after brain trauma: we want to understand to what extend a patient can become similar to a healthy participant. We face two challenges. First, we have less information on healthy participants than on the patients. Second, the values of the medical tests for patients, even after treatment started, remain well-separated from those of healthy people; this is typical for neurodegenerative diseases, but also for further brain impairments. Our approach encompasses methods for modelling patient evolution and for predicting the health improvement of different patients' subpopulations, i.e. prediction of label if they recovered or not. We test our approach on a cohort of patients treated after brain trauma and a corresponding cohort of controls. Keywords Traumatic brain injury Á Label prediction Á Evolution modelling Á Clustering Mathematics Subject Classification MSC code1 Á MSC code2 Á more The dataset used in this work was made available through the cooperation ''Data Mining and Stream Mining for Epidemiological Studies on the Human Brain'' (StreaMED) between the Centre of Biomedical Technology (CTB) of the University Polytecnica de Madrid and the Otto-von-Guericke University Magdeburg.
Alzheimers & Dementia, Jun 1, 2023
Clinical Neurophysiology, 2022
Clinical Neuropsychologist, Jun 28, 2018
Objective: Previous literature has shown that executive functions (EF) are related to performance... more Objective: Previous literature has shown that executive functions (EF) are related to performance in memory tasks. The fact that there are no psychometric tests that evaluate these two constructs simultaneously led a group of researchers to develop the Test of Memory Strategies (TSM). Given the potential importance of this instrument for neuropsychological evaluation, in this study, we aimed to evaluate the psychometric properties of the TMS in Portuguese sample. We also examined the effect of aging by exploring profiles of performance on the TMS, comparing young and elderly healthy subjects. Method: Total of 135 healthy participants were submitted to a neuropsychological assessment and were divided into four age groups: a group of young adults (25-35 years) and three groups of older individuals (aged 60-69 years, 70-79 years, and 80 or more years). Results: Findings supported the reliability of the TMS scores, based on analyses of internal consistency. As expected, factor analysis of the TMS scores revealed that the test yielded two factors, one capturing EF and the other memory. Correlations with classic neuropsychological tests supported convergent and discriminant validity of the TMS scores. The elderly groups presented more difficulties in creating and mobilizing memory strategies when compared with a younger group, after controlling for the influence of education, although both groups presented increases in performance throughout the five TMS subscales. Conclusions: The findings suggest that the TMS is an adequate measure to assess memory and EF, simultaneously, presenting adequate psychometric properties for a Portuguese sample.
Clinical Neurophysiology, Mar 1, 2011
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
Neuropsychology Review, 2005
The first two decades of cognitive neuroimaging research have provided a constant increase of the... more The first two decades of cognitive neuroimaging research have provided a constant increase of the knowledge about the neural organization of cognitive processes. Many cognitive functions (e.g. working memory) can now be associated with particular neural structures, and ongoing research promises to clarify this picture further, providing a new mapping between cognitive and neural function. The main goal of this paper is to outline conceptual issues that are particularly important in the context of imaging changes in neural function through recovery process. This review focuses primarily on studies made in stroke and traumatic brain injury patients, but most of the issues raised here are also relevant to studies using other acquired brain damages. Finally, we summarize a set of methodological issues related to functional neuroimaging that are relevant for the study of neural plasticity and recovery after rehabilitation.
Epilepsy & Behavior, 2009
The risk of cognitive decline after mesial temporal lobe (MTL) resection in the dominant hemisphe... more The risk of cognitive decline after mesial temporal lobe (MTL) resection in the dominant hemisphere for treatment of epilepsy has been assessed with the intracarotid amytal procedure and functional neuroimaging. In this study we used magnetoencephalography (MEG) to analyze memory profiles in patients with left hippocampal sclerosis (HS). Biomagnetic brain activity related to successful memory was compared in nine patients with left HS and nine age-matched controls. Patients manifested a higher number of activity sources over the right inferior parietal lobe in the late portion of the time window, and higher activity in the right than in the left MTL between 400 and 800 ms. This was reinforced by a À0.46 MTL laterality index, which indicates right MTL dominance. Controls showed a higher number of dipoles in the left anterior ventral prefrontal region, between 400 and 600 ms, and in the left MTL across the whole time window. Three patients who underwent a left temporal lobectomy, were seizure free, and who did not exhibit memory impairment after left temporal lobectomy, showed no activity in the left MTL presurgically. These results could support the ability of MEG to describe the time-modulated brain activity related to memory success in patients with epilepsy with left HS.
NeuroImage, 2011
The advent of new signal processing methods, such as non-linear analysis techniques, represents a... more The advent of new signal processing methods, such as non-linear analysis techniques, represents a new perspective which adds further value to brain signals' analysis. Particularly, Lempel-Ziv's Complexity (LZC) has proven to be useful in exploring the complexity of the brain electromagnetic activity. However, an important problem is the lack of knowledge about the physiological determinants of these measures. Although a correlation between complexity and connectivity has been proposed, this hypothesis was never tested in vivo. Thus, the correlation between the microstructure of the anatomic connectivity and the functional complexity of the brain needs to be inspected. In this study we analysed the correlation between LZC and fractional anisotropy (FA), a scalar quantity derived from diffusion tensors that is particularly useful as an estimate of the functional integrity of myelinated axonal fibers, in a group of sixteen healthy adults (all female, mean age 65.56 ± 6.06 years, interval 58-82). Our results showed a positive correlation between FA and LZC scores in regions including clusters in the splenium of the corpus callosum, cingulum, parahipocampal regions and the sagittal stratum. This study supports the notion of a positive correlation between the functional complexity of the brain and the microstructure of its anatomical connectivity. Our investigation proved that a combination of neuroanatomical and neurophysiological techniques may shed some light on the underlying physiological determinants of brain's oscillations.
Actas españolas de psiquiatría
Traditionally assessment of cognitive function has not been employed adequately in our medical co... more 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.
Lecture Notes in Computer Science, 2014
Neuropsychology, 2005
Changes in spatiotemporal profiles of brain magnetic activity were investigated in healthy volunt... more Changes in spatiotemporal profiles of brain magnetic activity were investigated in healthy volunteers as a function of varying demands for phonological storage of spoken pseudowords. Greater activity for the phonological memory task was restricted to the dorsolateral prefrontal cortex (DLPFC) in the left hemisphere. During performance of the memory task, activity was initially found in the left superior temporal gyrus (between 100 and 200 ms), followed by activity in the ventrolateral prefrontal, motor, and premotor cortices (between 200 and 300 ms). Activity in DLPFCs was first observed consistently across participants later, between 300 and 400 ms. The data are consistent with the purported role of posterior temporal cortices in phonological analysis and in the online storage of phonological information, the contribution of ventrolateral and motor processing areas in establishment and short-term maintenance of articulatory representations through rehearsal, and the role of DLPFCs in the executive control of the maintenance operation.
Brain, 2010
Cognitive processes require a functional interaction between specialized multiple, local and remo... more Cognitive processes require a functional interaction between specialized multiple, local and remote brain regions. Although these interactions can be strongly altered by an acquired brain injury, brain plasticity allows network reorganization to be principally responsible for recovery. The present work evaluates the impact of brain injury on functional connectivity patterns. Networks were calculated from resting-state magnetoencephalographic recordings from 15 brain injured patients and 14 healthy controls by means of wavelet coherence in standard frequency bands. We compared the parameters defining the network, such as number and strength of interactions as well as their topology, in controls and patients for two conditions: following a traumatic brain injury and after a rehabilitation treatment. A loss of delta-and theta-based connectivity and conversely an increase in alpha-and beta-band-based connectivity were found. Furthermore, connectivity parameters approached controls in all frequency bands, especially in slow-wave bands. A correlation between network reorganization and cognitive recovery was found: the reduction of delta-band-based connections and the increment of those based on alpha band correlated with Verbal Fluency scores, as well as Perceptual Organization and Working Memory Indexes, respectively. Additionally, changes in connectivity values based on theta and beta bands correlated with the Patient Competency Rating Scale. The current study provides new evidence of the neurophysiological mechanisms underlying neuronal plasticity processes after brain injury, and suggests that these changes are related with observed changes at the behavioural level.
Frontiers in human neuroscience, 2011
Plasticity is the mechanism underlying the brain's potential capability to compensate injury.... more Plasticity is the mechanism underlying the brain's potential capability to compensate injury. Recently several studies have shown how functional connections among the brain areas are severely altered by brain injury and plasticity leading to a reorganization of the networks. This new approach studies the impact of brain injury by means of alteration of functional interactions. The concept of functional connectivity refers to the statistical interdependencies between physiological time series simultaneously recorded in various areas of the brain and it could be an essential tool for brain functional studies, being its deviation from healthy reference an indicator for damage. In this article, we review studies investigating functional connectivity changes after brain injury and subsequent recovery, providing an accessible introduction to common mathematical methods to infer functional connectivity, exploring their capabilities, future perspectives, and clinical uses in brain injur...
Frontiers in Neurology, 2022
BackgroundStroke is the second leading cause of death worldwide and it causes important long-term... more BackgroundStroke is the second leading cause of death worldwide and it causes important long-term cognitive and physical deficits that hamper patients' daily activity. Neuropsychological rehabilitation (NR) has increasingly become more important to recover from cognitive disability and to improve the functionality and quality of life of these patients. Since in most stroke cases, restoration of functional connectivity (FC) precedes or accompanies cognitive and behavioral recovery, understanding the electrophysiological signatures underlying stroke recovery mechanisms is a crucial scientific and clinical goal.MethodsFor this purpose, a longitudinal study was carried out with a sample of 10 stroke patients, who underwent two neuropsychological assessments and two resting-state magnetoencephalographic (MEG) recordings, before and after undergoing a NR program. Moreover, to understand the degree of cognitive and neurophysiological impairment after stroke and the mechanisms of recove...