Ádám Feldmann

Morphometric changes of gray matter in Parkinson's disease with depression: a voxel-based morphometry study.

The origin of the high rate of depression in idiopathic Parkinsons disease (PD) is unknown. We applied voxel‐based morphometry (VBM), as a sensitive tool in detection of gray matter MR density alterations, to find differences in depressed and nondepressed PD patients. Patients with idiopathic PD were classified into depressed (DPD) and nondepressed (NDPD) groups based on the Montgomery‐Åsberg Depression Rating Scale (MADRS). Subsequently, a group comparisons were performed between depressed PD (n = 23), nondepressed PD (n = 27) and normal healthy controls (NC, n = 16). There was no difference in gray matter density comparing healthy controls to any PD groups. However, when NDPD and DPD cohorts were compared, density alteration of the bilateral orbitofrontal, bilateral rectal gyrus, and also the right superior temporal pole was detected in the depressed subgroup. Exploratory analyses revealed an inverse correlation of MADRS scores and severity of VBM alteration in these regions beside the right medial temporal gyrus, anterior and medial cingular gyrus, and parahippocampal gyrus. These results suggest that depression in PD is related to gray matter decrease in the bilateral orbitofrontal and right temporal regions as well as the limbic system.

The rubber hand illusion increases heat pain threshold

Accumulating evidence shows that manipulations of cortical body representation, for example, by simply viewing ones own body, can relieve pain in healthy subjects. Despite the widespread use of the rubber hand illusion (RHI) as an effective experimental tool for the manipulation of bodily awareness, previous studies examining the analgesic effect of the RHI have produced conflicting results.

IMPLANTED DEEP BRAIN STIMULATOR AND 1.0 TESLA MAGNETIC RESONANCE IMAGING

There is a great need for MRI examinations of patients who have previously undergone deep brain stimulator (DBS) implantation. The current guidelines pertain only to a 1.5‐Tesla horizontal‐bore scanner complying with strict safety regulations. Moreover, almost all published in vitro and in vivo studies concerning patient safety are carried out on 1.5 Tesla MR scanners. The aim of our work is to share our clinical experience of 1.0‐Tesla brain MR imaging. During the past four years, 34 patients with different types of implanted DBS systems underwent 1.0‐Tesla MR examinations to answer diagnostic or clinical questions. Apart from the scanner type applied, all other safety instructions were strictly followed. The MRI itself made no significant difference to the measured impedances or the stimulation parameters required to achieve the optimal therapeutic results. From theoretical considerations, it may be assumed that 1.0‐Tesla MRI can be performed safely on DBS‐implanted patients, provided that all other recommendations are adhered to. J. Magn. Reson. Imaging 2006.

Atrophy and decreased activation of fronto-parietal attention areas contribute to higher visual dysfunction in posterior cortical atrophy

Voxel-based morphometry and functional magnetic resonance imaging demonstrated severe atrophy and decreased activation of visual attention areas and occipital lobes in a patient with early posterior cortical atrophy compared with healthy controls and patients with early Alzheimers disease. Our complex approach indicates that structures responsible for attention can be damaged early in posterior cortical atrophy and may contribute to the characteristic decline in higher visual functions.

The impact of bilateral subthalamic deep brain stimulation on long-latency event-related potentials.

The analysis of long-latency event-related potentials (ERPs) is of importance in the evaluation of certain cognitive functions and in following their subsequent changes. The aim of the present study was to investigate whether deep brain stimulation (DBS) itself can cause changes in the configuration of the ERPs. Using a standard oddball auditory paradigm, we elicited auditory cognitive ERPs in 23 Parkinsons disease patients (in both DBS-ON and DBS-OFF conditions) and in 14 healthy controls. The P200 and P300 amplitudes and latencies, the motor reaction times and the accuracy of button pressing were compared between the DBS-ON and DBS-OFF states and subsequently correlated with the applied stimulation voltage and disease duration. Comparison of the DBS-ON and DBS-OFF conditions revealed that neither the amplitude nor the latency of the examined ERP components changed significantly. However, the behavioral and attentional aspects (e.g. the accuracy of the button pressing responses to the target signal) definitely improved after the DBS was turned on. Positive correlations were demonstrated between the P300 amplitudes over the central and frontal regions and the optimal stimulation voltage and between the disease duration and P300 latencies over the Cz and Fz sites. In conclusion, our data indicate that DBS may have different impacts on various electrophysiological parameters during the oddball paradigm.

Temperament and psychopathological syndromes specific susceptibility for rubber hand illusion

The aim of this study is to explore individual capacity for self-integration, susceptibility to the Rubber Hand Illusion (RHI) and the role of temperament factors in the emergence of body schema and body image dissociation. The RHI factors, proprioceptive drift, body ownership and body disownership were assessed in 48 university students. Personality and psychiatric vulnerability were measured by the Temperament and Character Inventory (TCI-R) and the Symptom Checklist-90-R (SCL-90-R). Our study pointed to the fact that the extent of behaviourally defined proprioceptive drift was associated with temperament factors, especially with Novelty Seeking and Harm Avoidance. Further, the ownership was associated with Symptom Checklist factors, especially with elevated Interpersonal Sensitivity and vulnerability to Schizotypy and Paranoid Ideation and elevated disownership score was found in the case of elevated Schizotypy, including a depersonalisation feeling when the RHI was induced. The RHI may be considered as a conflicting situation, in which a way to cope with incongruent multimodal, visual, haptic and proprioceptive stimulation provides an opportunity to test body integration and embodiment processes in healthy participants and patients without disadvantageous outcomes. The results support and replenish the two opposite processing models of the RHI with a third, temperament-based procedural mechanism.

Anxiety-dependent spatial navigation strategies in virtual and real spaces

The anxiety-related thigmotaxis strategy refers to a movement tactic to contact towards a larger object that serves as an orientation point from where the subject can find a safety background to begin route finding. This movement sequence towards a border of an enclosed place involves a tendency to avoid the inner zones and stay on the periphery is quantified by measuring the amount of path length spent in close contact with the wall. The Morris water maze (MWM) is a typical test for the hippocampalbased memory functions and goal-directed navigation (Morris 1981). The leading factor of exploration movement variation in the MWM is the thigmotaxis. During goaldirected exploration, the thigmotaxis inhibits the acquisition of the spatial relationships among the contextual cues, on the other hand serves as the definition of the border for an enclosed place and form of egocentric references to the proposed actions (Kallai et al 2005). This contradictory function of the anxiety-dependent thigmotaxis strategy reveals a basic neural organization conflict between the allocentric and egocentric reference frame-utilized spatial learning dynamics. A deeper insight is needed to identify the neuro-cognitive structure that involved in hold up this conflict. The hippocampus (HP) is a key structure in supporting spatial memory, spatial navigation, and in the construction of a spatial map of the surrounding space in rodents and in humans. The HP is also involved in coping with stressful situations. Changes in the tissue structure of the HP due to lesions or atrophy are associated with several neuropsychiatrical disorders, nevertheless only a few studies examined the HP volume differences in healthy participants, so the healthy functioning of the HP-dependent spatial learning and its neuro-cognitive basis in humans remains controversial. In humans, fMRI studies showed increased activity in the HP while performing a virtual orientation task. Maguire et al. (2000) found that the long duration navigation exercise correlated positively with the volume of right posterior HP and negatively with the anterior HP. But these studies remained open the role of the innate or exercise factors in relationship between spatial performances and HP volume. Studies with animals have revealed that sex, anxiety and lesion sites in several parts of the hippocampus and lateral caudate-putamen have an influence on the exploratory strategies in MWM (McDonald and White 1994). Thigmotaxis behaviour of rats in a MWM was characteristic during the first phase of place learning with dorsomedial, but not with dorsolateral caudate-putamen lesions. However, this type of lesion had no influence on the hidden platform acquisition in the subsequent test trials. On the other hand, a dry-land maze design study showed that both the lesion groups spent less time in the vicinity of the arena wall than the control rats. This latter evidenced by Devan et al. (1999) points to a contradictory phenomenon between learning and emotional processing, the communication of the hippocampus and the cortex via the caudate putamen. We determined two objectives for the present study: (a) measurement of thigmotaxis in successive trials of various spatial navigational tasks, (b) correlations between the use of thigmotaxis strategy, spatial learning expertise and the structural volumetry of the total brain adjusted amygdale and the hippocampi. J. Kállai (&) K. Karádi Á. Feldmann Institute of Behavioral Sciences, University of Pécs, Pecs, Hungary e-mail: janos.kallai@aok.pte.hu

Association of Gait Characteristics and Depression in Patients with Parkinson’s Disease Assessed in Goal-Directed Locomotion Task

Introduction. In the genesis of Parkinsons disease (PD) clinical phenomenology the exact nature of the association between bradykinesia and affective variables is unclear. In the present study, we analyzed the gait characteristics and level of depression in PD and healthy volunteers. Methods. Patients with PD (n = 48) and healthy controls (n = 52) were recruited for the present study. Walking speed, stride length, and cadence were compared between groups while participants completed a goal-directed locomotion task under visually controlled (VC) and visually noncontrolled conditions (VnC). Results. Significantly higher depression scores were found in PD comparing to healthy control groups. In PD, depression was associated with gait components in the VC wherein the place of the target was visible. In contrast, in healthy subjects the depression was associated with gait components in VnC wherein the location and image of the target were memorized and recalled. In patients with PD and depression, the visually deprived multitask augments the rate of cadence and diminishes stride length, while velocity remains relatively unchanged. The depression associated with gait characteristics as a comorbid affective factor in PD, and that impairs the coherence of gait pattern. Conclusion. The relationship between depression and gait parameters appears to indicate that PD not only is a neurological disease but also incorporates affective disturbances that associate with the regulation of gait characteristics.

Molecular Subgroups of Glioblastoma– an Assessment by Immunohistochemical Markers

Comprehensive molecular characterization of and novel therapeutic approaches to glioblastoma have been explored as a result of advancements in biotechnologies. In this study, we aimed to bring basic research discoveries closer to clinical practice and ultimately incorporate molecular classification into the routine histopathological evaluation of grade IV gliomas. Integrated results of genome-wide sequencing, transcriptomic and epigenomic analyses by The Cancer Genome Atlas Network defined the classic, proneural, neural and mesenchymal subtypes of this tumor. In a retrospective cohort, we analyzed selected subgroup-defining molecular markers in formalin-fixed paraffin-embedded surgical specimens by immunohistochemistry. Quantitative and qualitative scores of marker expression were tested in hierarchical cluster analyses to evaluate segregations of the molecular subgroups, which then were correlated with clinical parameters including patients’ age, gender and overall survival. Our study has confirmed the separation of molecular glioblastoma subgroups with clear trends regarding clinical correlations. Future analyses in a larger, prospective cohort using similar methods are expected to facilitate the development of a molecular diagnostic panel that may complement routine histological work up and support prognostication as well as treatment decisions in glioblastoma.

Neuronal coding of auditory sensorimotor gating in medial prefrontal cortex

Abstract The medial prefrontal cortex (mPFC) is thought to be an essential brain region for sensorimotor gating. The exact neuronal mechanisms, however, have not been extensively investigated yet by delicate single unit recording methods Prepulse inhibition (PPI) of the startle response is a broadly used important tool to investigate the inhibitory processes of sensorimotor gating. The present study was designed to examine the neuronal mechanisms of sensorimotor gating in the mPFC in freely moving rats. In these experiments, the animals were subjected to both pulse alone and prepulse + pulse stimulations. Head acceleration and the neuronal activity of the mPFC were simultaneously recorded. To adequately measure the startle reflex, a new headstage with 3D‐accelerometer was created. The duration of head acceleration was longer in pulse alone trials than in prepulse + pulse trial conditions, and the amplitude of head movements was significantly larger during the pulse alone than during the prepulse + pulse situations. Single unit activities in the mPFC were recorded by means of chronically implanted tetrodes during acoustic stimulation evoked startle response and PPI. High proportion of medial prefrontal cortical neurons responded to these stimulations by characteristic firing patterns: short duration equal and unequal excitatory, medium duration excitatory, and long duration excitatory and inhibitory responses were recorded. The present findings, first time in the literature, demonstrated the startle and PPI elicited neuronal activity changes of the mPFC, and thus, provided evidence for a key role of this limbic forebrain area in sensorimotor gating process.