Our researchers

Julio Artieda González-Granda

Research lines
Neurofisiologia Clínica y de sistemas. Oscilaciones cerebrales y dinámica de redes neurales. Neuromodulación en enfermedades neurodegenerativas
40, (Google Scholar, 01/06/2018)

Most recent scientific publications (since 2010)

Authors: Alegre, Manuel; Artieda, Julio, (Autor de correspondencia); Valencia, Miguel, (Autor de correspondencia)
ISSN 1935-861X  Vol. 11  Nº 1  2018  pp. 231 - 238
Background: High-frequency deep brain stimulation (DBS) has become a widespread therapy used in the treatment of Parkinson's Disease (PD) and other diseases. Although it has proved beneficial, much recent attention has been centered around the potential of new closed-loop DBS implementations. Objective: Here we present a new closed-loop DBS scheme based on the phase of the theta activity recorded from the motor cortex. By testing the implementation on freely moving 6-OHDA lesioned and control rats, we assessed the behavioral and neurophysiologic effects of this implementation and compared it against the classical high-frequency DBS. Results: Results show that both stimulation modalities produce significant and opposite changes on the movement and neurophysiological activity. Close-loop stimulation, far from improving the animals' behavior, exert contrary effects to those of high-frequency DBS which reverts the parkinsonian symptoms. Motor improvement during open-loop, high-frequency DBS was accompanied by a reduction in the amount of cortical beta oscillations while akinetic and disturbed behavior during close-loop stimulation coincided with an increase in the amplitude of beta activity. Conclusion: Cortical-phase-dependent close-loop stimulation of the STN exerts significant behavioral and oscillatory changes in the rat model of PD. Open-loop and close-loop stimulation outcomes differed dramatically, thus suggesting that the scheme of stimulation determines the output of the modulation even if the target structure is maintained. The current framework could be extended in future studies to identify the correct parameters that would provide a suitable control signal to the system. It may well be that with other stimulation parameters, this sort of DBS could be beneficial. (C) 2017 Elsevier Inc. All rights reserved.
Authors: Uriguen, J. A.; Garcia-Zapirain, B.; Artieda, Julio; et al.
Journal: PLOS ONE
ISSN 1932-6203  Vol. 12  Nº 9  2017  pp. e0184044
Idiopathic epilepsy is characterized by generalized seizures with no apparent cause. One of its main problems is the lack of biomarkers to monitor the evolution of patients. The only tools they can use are limited to inspecting the amount of seizures during previous periods of time and assessing the existence of interictal discharges. As a result, there is a need for improving the tools to assist the diagnosis and follow up of these patients. The goal of the present study is to compare and find a way to differentiate between two groups of patients suffering from idiopathic epilepsy, one group that could be followed-up by means of specific electroencephalographic (EEG) signatures (intercritical activity present), and another one that could not due to the absence of these markers. To do that, we analyzed the background EEG activity of each in the absence of seizures and epileptic intercritical activity. We used the Shannon spectral entropy (SSE) as a metric to discriminate between the two groups and performed permutation-based statistical tests to detect the set of frequencies that show significant differences. By constraining the spectral entropy estimation to the [6.25-12.89) Hz range, we detect statistical differences (at below 0.05 alpha-level) between both types of epileptic patients at all available recording channels. Interestingly, entropy values follow a trend that is inversely related to the elapsed time from the last seizure. Indeed, this trend shows asymptotical convergence to the SSE values measured in a group of healthy subjects, which present SSE values lower than any of the two groups of patients. All these results suggest that the SSE, measured in a specific range of frequencies, could serve to follow up the evolution of patients suffering from idiopathic epilepsy. Future studies remain to be conducted in order to assess the predictive value of this approach for the anticipation of seizures.
Authors: Alegre, Manuel; Molero, Patricio; Valencia, Miguel; et al.
ISSN 0165-1781  Vol. 247  2017  pp. 214 - 221
The symptoms of schizophrenia might be mediated by a cortical network disconnection which may disrupt the cortical oscillatory activity. Steady-state responses are an easy and consistent way to explore cortical oscillatory activity. A chirp-modulated tone (increasing the frequency of the modulation in a linear manner) allows a fast measure of the steady-state response to different modulation rates. With this approach, we studied the auditory steady-state responses in two groups of patients with schizophrenia (drug-naive and treated with atypical antipsychotic drugs), in order to assess the differences in their responses with respect to healthy subjects, and study any potential effect of medication. Drug-naive patients had reduced amplitude and inter-trial phase coherence of the response in the 30-50Hz range, and reduced amplitude of the response in the 90-100Hz range, when compared to controls. In the treated patients group, the response in the 30-50Hz range was normalized to values similar to the control group, but the reduction in amplitude in the 90-100Hz range remained as in the drug-naive group. These results suggest that gamma activity impairment in schizophrenia is a complex phenomenon that affects a wide band of frequencies and may be influenced by antipsychotic treatment.
Authors: Tubia, Imanol, (Autor de correspondencia); Artieda, Julio; et al.
Vol. 251  2016  pp. 241 - 247
Authors: López, Jon; Alegre, Manuel; Artieda, Julio, (Autor de correspondencia); et al.
ISSN 0924-977X  Vol. 25  Nº 8  2015  pp. 1375 - 1387
Recent studies have suggested the implication of the basal ganglia in the pathogenesis of schizophrenia. To investigate this hypothesis, here we have used the ketamine model of schizophrenia to determine the oscillatory abnormalities induced in the rat motor circuit of the basal ganglia. The activity of free moving rats was recorded in different structures of the cortico-basal ganglia circuit before and after an injection of a subanesthesic dose of ketamine (10mg/kg). Spectral estimates of the oscillatory activity, phase-amplitude cross-frequency coupling interactions (CFC) and imaginary event-related coherence together with animals¿ behavior were analyzed. Oscillatory patterns in the cortico-basal ganglia circuit were highly altered by the effect of ketamine. CFC between the phases of low-frequency activities (delta, 1-4; theta 4-8Hz) and the amplitude of high-gamma (~80Hz) and high-frequency oscillations (HFO) (~150Hz) increased dramatically and correlated with the movement increment shown by the animals. Between-structure analyses revealed that ketamine had also a massive effect in the low-frequency mediated synchronization of the HFO's across the whole circuit. Our findings suggest that ketamine administration results in an aberrant hypersynchronization of the whole cortico-basal circuit where the tandem theta/HFO seems to act as the main actor in the hyperlocomotion shown by the animals. Here we stress the importance of the basal ganglia circuitry in the ketamine model of schizophrenia and leave the door open to further investigations devoted to elucidate to what extent these abnormalities also reflect the prominent neurophysiological deficits observed in schizophrenic patients.
Authors: Iriarte, Jorge; Fernández, Secundino; et al.
ISSN 0959-9851  Vol. 25  Nº 4  2015  pp. 225 - 232
BACKGROUND: Cardiac autonomic tone after long-term continuous positive airway pressure therapy in patients with obstructive sleep apnea remains unexplored. METHODS: Thirty patients with obstructive sleep apnea (14 with moderate and 16 with severe obstructive sleep apnea) were studied during a baseline polysomnographic study, after a full night of acute continuous positive airway pressure treatment, and after long-term (~2 years) chronic continuous positive airway pressure therapy. Twenty age- and gender-matched controls with baseline sleep study were selected for comparison purposes. Cross-spectral analysis and the low-frequency (LF) and high-frequency (HF) components of the heart rate variability were computed separately over 10-min ECG epochs during rapid eye movement sleep, non-rapid eye movement sleep, and wakefulness. RESULTS: During the baseline study, obstructive sleep apnea patients exhibited increased LF, decreased HF, and increased LF/HF ratio during sleep when compared to controls. In a multiple regression model, the mean oxygen saturation explained the increased LF during rapid and non-rapid eye movement sleep in obstructive sleep apnea patients. Acute continuous positive airway pressure therapy decreased the LF modulations and the LF/HF ratio and increased the HF modulations during sleep in patients with severe obstructive sleep apnea. Long-term continuous positive airway pressure therapy decreased LF modulations and LF/HF ratio with increased HF modulations during sleep in patients with moderate and severe obstructive sleep apnea. CONCLUSIONS: Long-term continuous positive airway pressure reduces the sympathovagal imbalance in patients with moderate and severe obstructive sleep apnea, both during rapid and non-rapid eye movement sleep. Continuous positive airway pressure seems to exert its changes in cardiac autonomic modulation by decreasing the burden of nocturnal hypoxia.
Authors: Iriarte, Jorge, (Autor de correspondencia); Fernández, Secundino; et al.
ISSN 1388-2457  Vol. 125  Nº 9  2014  pp. 1783 - 1791
OBJECTIVE: The pathophysiological basis of obstructive sleep apnea (OSA) is not completely understood and likely varies among patients. In this regard, some patients with OSA do not exhibit hypoxemia. We aimed to analyze the clinical, sleep, and autonomic features of a group of patients with severe OSA without hypoxia (OSA-h) and compare to OSA patients with hypoxia (OSA+h) and controls. METHODS: Fifty-six patients with OSA-h, 64 patients with OSA+h, and 44 control subjects were studied. Clinical and sleep features were analyzed. Besides, time- and frequency-domain heart rate variability (HRV) measures comprising the mean R-R interval, the standard deviation of the RR intervals (SDNN), the low frequency (LF) oscillations, the high frequency (HF) oscillations, and the LF/HF ratio, were calculated across sleep stages during a one-night polysomnography. RESULTS: OSA-h patients had a lower body mass index, a lower waist circumference, lower apnea duration, and a higher frequency of previous naso-pharyngeal surgery when compared to OSA+h patients. In terms of heart rate variability, OSA+h had increased LF oscillations (i.e., baroreflex function) during N1-N2 and rapid eye movement (REM) sleep when compared to OSA-h and controls. Both OSA+h and OSA-h groups had decreased HF oscillations (i.e., vagal inputs) during N1-N2, N3 and REM sleep when compared to controls. The LF/HF ratio was increased during N1-N2 and REM sleep, only in patients with OSA+h. CONCLUSIONS: Patients with OSA-h exhibit distinctive clinical, sleep, and autonomic features when compared to OSA with hypoxia. SIGNIFICANCE: OSA is a heterogeneous entity. These differences must be taken into account in future studies when analyzing therapeutic approaches for sleep apnea patients.
Authors: Alegre, Manuel; Valencia, Miguel; et al.
Vol. 121  Nº 4  2014  pp. 385 - 390
Authors: Toledo, Juan Bautista; López, Jon; et al.
Vol. 64  2014  pp. 60 - 65
Authors: Iriarte, Jorge; Alegre, Manuel; et al.
ISSN 1388-2457  Vol. 125  Nº 1  2014  pp. 208 - 210
Authors: Toledo, Juan Bautista; López, Jon; et al.
ISSN 0969-9961  Vol. 64  2014  pp. 60-65
p-FOG patients showed higher power in the high-beta band (F=11.6, p=0.002) that was significantly reduced after l-dopa administration along with suppression of FOG (F=4.6, p=0.042). High-beta cortico-STN coherence was maximal for midline cortical EEG electrodes, whereas the low-beta band was maximal for lateral electrodes (¿(2)=20.60, p<0.0001). CONCLUSIONS: The association between freezing of gait, high-beta STN oscillations and cortico-STN coherence suggests that this oscillatory activity might interfere in the frontal cortex-basal ganglia networks, thereby participating in the pathophysiology of FOG in PD.
Authors: Valencia, Miguel; Chavez, Mario; Artieda, Julio; et al.
ISSN 1522-1598  Vol. 111  Nº 2  2014  pp. 434 - 440
Authors: Iriarte, Jorge; Alegre, Manuel; et al.
ISSN 1388-2457  Vol. 125  Nº 1  2014  pp. 208-210
Authors: Iriarte, Jorge; Alegre, Manuel; et al.
ISSN 1872-8952  Vol. 125  Nº 1  2014  pp. 208 - 210
Authors: Urrestarazu, Elena; López, Jon; et al.
Journal: SLEEP
ISSN 0161-8105  Vol. 36  Nº 6  2013  pp. 933 - 940
OBJECTIVE: To assess autonomic function by heart rate variability (HRV) during sleep in patients with sleep related alveolar hypoventilation (SRAH) and to compare it with that of patients with obstructive sleep apnea (OSA) and control patients. DESIGN: Cross-sectional study. SETTING: Sleep Unit, University Hospital of University of Navarra. PATIENTS: Fifteen idiopathic and obesity related-SRAH patients were studied. For each patient with SRAH, a patient with OSA, matched in age, sex, body mass index (BMI), minimal oxygen saturation (SatO2), and mean SatO2 was selected. Control patients were also matched in age, sex, and BMI with patients with OSA and those with SRAH, and in apnea/hypopnea index (AHI) with patients with SRAH. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Time- and frequency-domain HRV measures (R-R, standard deviation of normal-to-normal RR interval [SDNN], very low frequency [VLF], low frequency [LF], high frequency [HF], LF/HF ratio) were calculated across all sleep stages as well as during wakefulness just before and after sleep during a 1-night polysomnography. In patients with SRAH and OSA, LF was increased during rapid eye movement (REM) when compared with control patients, whereas HF was decreased during REM and N1-N2 sleep stages. The LF/HF ratio was equally increased in patients with SRAH and OSA during REM and N1-N2. Correlation analysis showed that LF and HF values during REM sleep were correlated with minimal SatO2 and mean SatO2. CONCLUSIONS: Patients with SRAH exhibited an abnormal cardiac tone during sleep. This fact appears to be related to the severity of nocturnal oxygen desaturation. Moreover, there were no differences between OSA and SRAH, supporting the hypothesis that autonomic changes in OSA are primarily related to a reduced nocturnal oxygen saturation, rather than a consequence of other factors such as nocturnal respiratory events.
Authors: Urrestarazu, Elena; Alegre, Manuel; et al.
ISSN 1388-2457  Vol. 124  Nº 6  2013  pp. 1163 - 1168
OBJECTIVE: Cardiac physiology during sleep in Parkinson's disease (PD) remains poorly explored. We studied heart rate variability (HRV) across sleep stages in PD patients and correlated the results with clinical features. METHODS: Cross-sectional study comprising 33 patients with PD and 29 controls matched for age, gender, and number of apneas/hypopneas per hour. HRV measures, (mean R-R interval, SDNN, ULF, VLF, LF, HF and LF/HF) were calculated separately for all sleep stages as well as wakefulness just before and after sleep during one-night polysomnography. Correlation analysis was performed between HRV values and PD patients' characteristics. RESULTS: The mean R-R interval was lower in all sleep stages in PD patients when compared with controls. VLF and LF were lower during REM sleep in PD patients. HF during N1-N2 stage was higher in PD. We found inverse correlations between VLF and LF during REM sleep and UPDRS-ON and UPDRS-OFF. CONCLUSION: VLF and LF during REM sleep might constitute surrogate markers of disease severity. SIGNIFICANCE: These findings provide additional clinical evidence of the autonomic impairment commonly observed in PD, and prove that cardiac autonomic dysfunction during REM sleep is correlated with disease severity.
Authors: Chavez, Mario, (Autor de correspondencia); De Vico Fallani, Fabrizio; Valencia, Miguel; et al.
ISSN 1559-0089  Vol. 11  Nº 3  2013  pp. 355 - 366
Recent findings suggest that the preparation and execution of voluntary self-paced movements are accompanied by the coordination of the oscillatory activities of distributed brain regions. Here, we use electroencephalographic source imaging methods to estimate the cortical movement-related oscillatory activity during finger extension movements. Then, we apply network theory to investigate changes (expressed as differences from the baseline) in the connectivity structure of cortical networks related to the preparation and execution of the movement. We compute the topological accessibility of different cortical areas, measuring how well an area can be reached by the rest of the network. Analysis of cortical networks reveals specific agglomerates of cortical sources that become less accessible during the preparation and the execution of the finger movements. The observed changes neither could be explained by other measures based on geodesics or on multiple paths, nor by power changes in the cortical oscillations.
Authors: Iriarte, Jorge; Fernández, Secundino; et al.
ISSN 1389-9457  Vol. 14  Nº 2  2013  pp. 217 - 219
Objectives This is a video case report of a 58-year-old male patient with severe obstructive sleep apnea (OSA) who underwent a pharyngo-laryngoscopy during non-drug-induced sleep. Methods The pharyngo-laryngoscopy was performed transnasally during a 30-minute nap, in the afternoon, with a flexible endoscope in supine position. During the procedure, the patient was monitored with polysomnography. Results The patient slept for 20 minutes in supine position, reaching N2 sleep stage. During the sleep, 15 respiratory events (apneas or hypopneas) were recorded. The video-recording showed that, during apneas, the obstruction at the pharyngeal level was never complete, although the nasal sensor showed a total stop in the nasal airflow. Conclusions This case highlights that OSA could not be as obstructive as generally thought, at least during N2 sleep; moreover, it suggests that apneic episodes are not a totally passive and monomorphic phenomenon, but a rather complex event.
Authors: Valencia, Miguel; Artieda, Julio; Bolam, J Paul; et al.
Journal: {PLOS} ONE
ISSN 1932-6203  Vol. 8  Nº 7  2013  pp. e67540
Authors: López, Jon; Nicolas, Maria Jesus; Cordón, Iván; et al.
ISSN 1662-5110  Vol. 7  2013  pp. 155
Authors: Alegre, Manuel; López, Jon; Obeso Martin, I.; et al.
ISSN 0014-4886  Vol. 239  2013  pp. 1 - 12
Normal actions and behaviors often require inhibition of unwanted and inadequate movements. Motor inhibition has been studied using the stop signal task, in which participants are instructed to respond to a go signal. Sporadically, a stop signal is also delivered after a short interval following the go signal, prompting participants to inhibit their already started response to the go signal. Functional MRI studies using this paradigm have implicated the activation of the subthalamic nucleus in motor inhibition. We directly recorded subthalamic nucleus activity from bilaterally implanted deep brain stimulation electrodes in a group of 10 patients with Parkinson's disease, during performance of the stop signal task. Response inhibition was associated with specific changes in subthalamic activity in three different frequency bands. Response preparation was associated with a decrease in power and cortico-subthalamic coherence in the beta band (12-30 Hz), which was smaller and shorter when the response was successfully inhibited. In the theta band, we observed an increase in frontal cortico-subthalamic coherence related to the presence of the stop signal, which was highest when response inhibition was unsuccessful. Finally, a specific differential pattern of gamma activity was observed in the "on" motor state. Performance of the response was associated with a significant increase in power and cortico-subthalamic coherence, while successful inhibition of the response was associated with a bilateral decrease in subthalamic power and cortico-subthalamic coherence. Importantly, this inhibition-related decrease in gamma activity was absent in the four patients with dopamine-agonist related impulse-control disorders. Our results provide direct support for the involvement of the subthalamic nucleus in response inhibition and suggest that this function may be mediated by a specific reduction in gamma oscillations in the cortico-subthalamic connection.
Authors: Valencia, Miguel; López, Jon; Nicolas, Maria Jesus; et al.
Vol. 45  Nº 5  2012  pp. 619 - 628
Authors: Kufoy, E.; López, Jon; et al.
Journal: PLOS ONE
ISSN 1932-6203  Vol. 7  Nº 3  2012  pp. e33769
Introduction: Obstructive Sleep Apnea (OSA) is a major risk factor for cardiovascular disease. The goal of this study was to demonstrate whether the use of CPAP produces significant changes in the heart rate or in the heart rate variability of patients with OSA in the first night of treatment and whether gender and obesity play a role in these differences. Methods: Single-center transversal study including patients with severe OSA corrected with CPAP. Only patients with total correction after CPAP were included. Patients underwent two sleep studies on consecutive nights: the first night a basal study, and the second with CPAP. We also analyzed the heart rate changes and their relationship with CPAP treatment, sleep stages, sex and body mass index. Twenty-minute segments of the ECG were selected from the sleep periods of REM, no-REM and awake. Heart rate (HR) and heart rate variability (HRV) were studied by comparing the R-R interval in the different conditions. We also compared samples from the basal study and CPAP nights. Results: 39 patients (15 females, 24 males) were studied. The mean age was 50.67 years old, the mean AHI was 48.54, and mean body mass index was 33.41 kg/m(2) (31.83 males, 35.95 females). Our results showed that HRV (SDNN) decreased after the use of CPAP during the first night of treatment, especially in non-REM sleep. Gender and obesity did not have any influence on our results. Conclusions: These findings support that cardiac variability improves as an acute effect, independently of gender or weight, in the first night of CPAP use in severe OSA patients, supporting the idea of continuous use and emphasizing that noncompliance of CPAP treatment should be avoided even if it is just once.
Authors: Alegre, Manuel, (Autor de correspondencia); López, Jon; Alonso-Frech, F.; et al.
ISSN 0885-3185  Vol. 27  Nº 9  2012  pp. 1176 - 1179
From a neurophysiological viewpoint, patients exhibited oscillatory activity typical of the "on" medication state during diphasic dyskinesias. The minimal presence of gamma activity during diphasic dyskinesias, however, suggests that this "on" state might be incomplete or limited to dopaminergic mechanisms affecting the lower limbs.
Authors: López, Jon; Valencia, Miguel; Alegre, Manuel; et al.
Journal: PLOS ONE
ISSN 1932-6203  Vol. 6  Nº 7  2011  pp. e21814-
Authors: Nicolás, María Jesus, (Autor de correspondencia); López, Jon; Valencia, Miguel; et al.
Journal: PLOS ONE
ISSN 1932-6203  Vol. 6  Nº 7  2011  pp. e21814
Authors: Iriarte, Jorge; Fernández, Secundino; Fernández-Arrechea, Natalia; et al.
ISSN 1520-9512  Vol. 15  Nº 2  2011  pp. 229 - 235
Purpose: Catathrenia (nocturnal groaning) is a rare and relatively little-understood parasomnia. The characteristics of the sound and the recordings are not similar in all the relevant research papers. Indeed, there is currently some discussion regarding whether or not this is a single entity. For some authors, catathrenia is a particular form of parasomnia; for others, it may be a variant of snoring or a respiratory problem. The goal is to establish whether or not catathrenia may be regarded as an expiratory vocal sound. An attempt was made to classify the origin of this sound according to its sound structure. Methods: We present the sound analysis of two patients, a man and a woman, with clinically diagnosed catathrenia and we compared them with the analysis of snoring. We use the spectrogram and the oscillogram. We classified the sounds according to the Yanagihara criteria. Results: The vocal nature of the sound was confirmed, and several significant differences to some snoring sounds were discovered. The analysis of the catathrenia samples demonstrated that these signals are type II according to Yanagihara classification; these signals had a very short jitter, and had formants and harmonics. However, snoring is a type III, very irregular and had formants but not harmonics. Conclusions: The oscillogram and the spectrogram in these patients show that the origins of the sounds are clearly different: catathrenia is laryngeal, while snoring is guttural. Catathrenia cannot be considered as expiratory snoring.
Authors: Rodríguez, María Cruz; López, Jon; et al.
Journal: BRAIN
ISSN 0006-8950  Vol. 134  Nº 1  2011  pp. 36-49
Behavioural abnormalities such as impulse control disorders may develop when patients with Parkinson's disease receive dopaminergic therapy, although they can be controlled by deep brain stimulation of the subthalamic nucleus. We have recorded local field potentials in the subthalamic nucleus of 28 patients with surgically implanted subthalamic electrodes. According to the predominant clinical features of each patient, their Parkinson's disease was associated with impulse control disorders (n = 10), dyskinesias (n = 9) or no dopaminergic mediated motor or behavioural complications (n = 9). Recordings were obtained during the OFF and ON dopaminergic states and the power spectrum of the subthalamic activity as well as the subthalamocortical coherence were analysed using Fourier transform-based techniques. The position of each electrode contact was determined in the postoperative magnetic resonance image to define the topography of the oscillatory activity recorded in each patient. In the OFF state, the three groups of patients had similar oscillatory activity. By contrast, in the ON state, the patients with impulse control disorders displayed theta-alpha (4-10 Hz) activity (mean peak: 6.71 Hz) that was generated 2-8 mm below the intercommissural line. Similarly, the patients with dyskinesia showed theta-alpha activity that peaked at a higher frequency (mean: 8.38 Hz) and was generated 0-2 mm below the intercommissural line. No such activity was detected in patients that displayed no dopaminergic side effects. Cortico-subthalamic coherence was more frequent in the impulsive patients in the 4-7.5 Hz range in scalp electrodes placed on the frontal regions anterior to the primary motor cortex, while in patients with dyskinesia it was in the 7.5-10 Hz range in the leads overlying the primary motor and supplementary motor area. Thus, dopaminergic side effects in Parkinson's disease are associated with oscillatory activity in the theta-alpha band, but at different frequencies and with different topography for the motor (dyskinesias) and behavioural (abnormal impulsivity) manifestations. These findings suggest that the activity recorded in parkinsonian patients with impulse control disorders stems from the associative-limbic area (ventral subthalamic area), which is coherent with premotor frontal cortical activity. Conversely, in patients with l-dopa-induced dyskinesias such activity is recorded in the motor area (dorsal subthalamic area) and it is coherent with cortical motor activity. Consequently, the subthalamic nucleus appears to be implicated in the motor and behavioural complications associated with dopaminergic drugs in Parkinson's disease, specifically engaging different anatomo-functional territories
Authors: Rodríguez, María Cruz; López, Jon; et al.
Journal: BRAIN
ISSN 0006-8950  Vol. 134  Nº Pt.1  2011  pp. 36-49
Authors: Alegre, Manuel; Guridi, Jorge; Artieda, Julio;
Journal: Journal of the Neurological Sciences
ISSN 0022-510X  Vol. 310  Nº 1-2  2011  pp. 194 - 196
Authors: Aymerich, MS; López, Jon; Boncaventura, J; et al.
ISSN 1537-744X  Vol. 11  2011  pp. 1995 - 2010
Understanding the trafficking of G-protein-coupled receptors (GPCRs) and their regulation by agonists and antagonists is fundamental to develop more effective drugs. Optical methods using fluorescent-tagged receptors and spinning disk confocal microscopy are useful tools to investigate membrane receptor dynamics in living cells. The aim of this study was to develop a method to characterize receptor dynamics using this system which offers the advantage of very fast image acquisition with minimal cell perturbation. However, in short-term assays photobleaching was still a problem. Thus, we developed a procedure to perform a photobleaching-corrected image analysis. A study of short-term dynamics of the long isoform of the dopamine type 2 receptor revealed an agonist-induced increase in the mobile fraction of receptors with a rate of movement of 0.08¿¿m/s For long-term assays, the ratio between the relative fluorescence intensity at the cell surface versus that in the intracellular compartment indicated that receptor internalization only occurred in cells co-expressing G protein-coupled receptor kinase 2. These results indicate that the lateral movement of receptors and receptor internalization are not directly coupled. Thus, we believe that live imaging of GPCRs using spinning disk confocal image analysis constitutes a powerful tool to study of receptor dynamics.
Authors: Pérez, Marta; Nicolas, Maria Jesus; Valencia, Miguel; et al.
ISSN 1872-6240  Vol. 1310  2010  pp. 58 - 67
Authors: López, Jon; Tainta, Mikel; Rodríguez, María Cruz; et al.
ISSN 1529-2401  Vol. 30  Nº 19  2010  pp. 6667 - 6677
Authors: Alegre, Manuel; et al.
Journal: Molecular Therapy
ISSN 1525-0016  Vol. 19  Nº 2  2010  pp. 243 - 250
Acute intermittent porphyria (AIP) is characterized by a hereditary deficiency of hepatic porphobilinogen deaminase (PBGD) activity. Clinical features are acute neurovisceral attacks accompanied by overproduction of porphyrin precursors in the liver. Recurrent life-threatening attacks can be cured only by liver transplantation. We developed recombinant adeno-associated virus (rAAV) vectors expressing human PBGD protein driven by a liver-specific promoter to provide sustained protection against induced attacks in a predictive model for AIP. Phenobarbital injections in AIP mice induced porphyrin precursor accumulation, functional block of nerve conduction, and progressive loss of large-caliber axons in the sciatic nerve. Hepatocyte transduction showed no gender variation after rAAV2/8 injection, while rAAV2/5 showed lower transduction efficiency in females than males. Full protection against induced phenobarbital-attacks was achieved in animals showing over 10% of hepatocytes expressing high amounts of PBGD. More importantly, sustained hepatic expression of hPBGD protected against loss of large-caliber axons in the sciatic nerve and disturbances in nerve conduction velocity as induced by recurrent phenobarbital administrations. These data show for the first time that porphyrin precursors generated in the liver interfere with motor function. rAAV2/5-hPBGD vector can be produced in sufficient quantity for an intended gene therapy trial in patients with recurrent life-threatening porphyria attacks.

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1990- Director del Servicio de Neurofisiología Clínica. Clínica Universitaria de Navarra. Universidad de Navarra y Centro de Investigación Médica Aplicada (CIMA) 2008- Director del Programa de Doctorado de Neurociencia y Cognición. Facultad de Medicina. Universidad de Navarra. Mención de calidad MCD 2003-00695 renovado hasta la última convocatoria y mención de excelencia otorgado por el Ministerio de Educación hasta el 2014 (MEE2011-0224). 2011- Catedráticode Medicina (Neurología). Facultad de Medicina. Universidad de Navarra. Acreditación como Catedrático de Universidad en Ciencias de la Salud (Medicina). ANECA.. 2011. 2013- Coordinador del Área de Neurociencias del Instituto de Investigación sanitaria de Navarra (IdiSNA) 2013- Académico correspondiente (Neurofisiología Clínica) Real Academia Nacional de Medicina de España
Otros Puestos Ocupados 1993-2000 Director del Departamento de Neurología y Neurocirugía Clínica Universitaria y Facultad de Medicina de la Universidad de Navarra 2003-2009 Vicedecano. Facultad de Medicina. Universidad de Navarra 2003-2007 Miembro Junta Directiva del Centro Investigación Médica Aplicada (CIMA) Universidad de Navarra 2007-2014 Director del Área de Neurociencias. Centro de Investigación Médica Aplicada (CIMA). Universidad de Navarra 2008-2014 Director Master Universitario de Neurociencia y Cognición. Facultad de Medicina. Universidad de Navarra