Clinical Neuroscience

[Analysis of mental arithmetic task by the “minimum spanning tree” method]

BOHA Roland1,2, TÓTH Brigitta1,2, KARDOS Zsófia3,2, FILE Bálint4, GAÁL Zsófia Anna2, MOLNÁR Márk5,2

MAY 30, 2016

Clinical Neuroscience - 2016;69(05-06)


[Goals - In the present study basic arithmetic induced rearrangements in functional connections of the brain were investigated by using graph theoretical analysis what becomes increasingly important both in theoretical neuroscience and also in clinical investigations. Research questions - During mental arithmetic operations (working) memory plays an important role, but there are only a few studies in which an attempt was made to separate this effect from the process of arithmetic operations themselves. The goal of our study was to separate the neural networks involved in cognitive functions. Methods - As an attempt to clarify this issue the graph-theoretical “minimal spanning tree” method was used for the analysis of EEG recorded during task performance. The effects of passive viewing, number recognition and mental arithmetic on PLI based minimal spanning trees (MST) were investigated on the EEG in young adults (adding task: 17 subjects; passive viewing and number recognition: 16 subjects) in the θ (4-8 Hz) frequency band. Results - Occipital task relevant synchronization was found by using the different methods, probably related to the effect of visual stimulation. With respect to diameter, eccentricity and fraction of leafs different task-related changes were found. Discussion - It was shown that the task related changes of various graph indices are capable to identify networks behind the various relevant dominant functions. Thus the “minimal spanning tree” method is suitable for the analysis of the reorganization of the brain with respect to cognitive functions.]


  1. ELTE, PPK, Pszichológiai Doktori Iskola, Budapest
  2. MTA, Természettudományi Kutatóközpont, Kognitív Idegtudományi és Pszichológiai Intézet, Budapest
  3. BME, Kognitív Tudományi Tanszék, Budapest
  4. PPKE, Információs Technológiai Kar, Budapest
  5. ELTE, PPK, Pszichológiai Intézet, Budapest



Further articles in this publication

Clinical Neuroscience

[Selective dorsal rhizotomy in the treatment of spasticity - Hungarian experiences ]

FEKETE Gábor, NOVÁK László, VEKERDY-NAGY Zsuzsanna, BOGNÁR László

[Objective - We summarize our initial experiences with selective dorsal rhizotomy that we introduced in Hungary to manage the spasticity of patients with cerebral palsy. Patients and methods - Thirty spastic patients were enrolled in our study. All of the patients were operated between July 2014 and June 2015. We performed selective dorsal rhizotomy from a single-level approach at the level of conus medullaris in all cases, with electrophysiological control. Results - We could perform the surgery in all cases safely. Adverse events related either to damage of neurological structures, or to surgery did not occur. The planned rehabilitation courses before and after the operations are in progress in all cases. Conclusion - Selective dorsal rhizotomy is an irreversible surgical intervention to treat spasticity. With sufficient experience and electrophysiological control it can be performed safely, and the early results are promising. ]

Clinical Neuroscience

[Experiences of hypothalamic hamartoma surgeries]

NOVÁK László, KISS Máté Tamás, KLEKNER Álmos, NAGY Andrea, FEDORCSÁK Imre, BOGNÁR László

[Background and purpose - Hypothalamic hamartomas are focal, benign congenital malformations that frequently associated with gelastic seizures. Behavioural disturbances, cognitive decline and the appearance of precocious puberty can also be observed. The most effective way to relieve the symptoms is the surgical disconnection between the hamartoma and the hypothalamus. In our study, we retrospectively analyzed the surgical indications and effectiveness of each approach. Methods - Between 1996 and 2014 we operated on 10 hypothalamic hamartomas. Endoscopic assisted resection was performed in three patients. Six patients underwent direct microsurgical resection in various approaches and one patient was treated with Gamma Knife. Results - We achieved significant decrease in the number of seizures in every patient presenting with various seizure types. The surgical resection was effective in the arresting of the puberty praecox as well. However the surgery of these lesions at their special location holds the danger of the appearance of new endocrinological symptoms. According to our observations the operation on hamartoma less effectively ameliorates the psychiatric symptoms than the others. Conclusion - The surgical treatment is effective in the reduction of the initial symptoms and we had no mortality. According to our analysis therapeutic success is anticipated but we couldn’t archive total symptomatic relief in every case. The first approach to these lesions should be the surgery which type must be tailored to each patient.]

Clinical Neuroscience

Paraoxonáz-1-aktivitás és fenotípusos megjelenése sclerosis multiplexben

KURTULUS Fatma, YAMAN Aylin, ELLIDAG Yasar Hamit, EREN Esin, GÖMCELI Bicer Yasemin, YILMAZ Necat

Introduction - Human serum paraoxonase (PON1) and arylesterase (ARE) are lipophilic antioxidant enzymes. PON-1 serum activity diverges in individuals and populations, which might be due to polymorphisms in the PON-1 gene. The PON1 activity phenotyping method, based on the ratio of the stimulated PON activity and the ARE activity, could determine the low-activity homozygotes (QQ), intermediate activity heterozygotes (QR), and high-activity homozygotes (RR) regardless of the genotype. The aim of the present study was to determine the PON1 phenotype distribution and enzymatic activity of PON1 and ARE in multiple sclerosis (MS) patients. Materials and methods - Thirty-four relapsing remitting MS (RRMS) patients (22 females and 12 males; median age 42 (range 20-55) years) in the remission phase and thirty-four age-sex matched healthy controls (19 females and 15 males; median age 37 (21-60) years) were included in this study. All patients had clinically definite MS according to McDonald’s criteria. Results - Serum PON1 and ARE enzyme activities, as well as salt-stimulated PON1, were not significantly different between the patient and control groups. Phenotype distributions were as follows: QQ 58.8%, QR 38.2%, and RR 3% in MS patients (n=34); QQ 44.1%, QR 50%, and RR 5.9% in the control group (n=34). QQ (low activity) phenotypic distribution was more common in MS patients than controls, but this difference was not significant (p=0.14). Conclusions - Our results did not reveal meaningful relationships between PON1 activity or PON1 phenotypes and MS. More studies in larger samples and in all phases of the disease are needed in the future.

Clinical Neuroscience

[New opportunities in neuro-rehabilitation: Robot mediated therapy in conditons post central nervous system impairments]

FAZEKAS Gábor, TAVASZI Ibolya, TÓTH András

[Decreasing the often-seen multiple disabilities as a consequence of central nervous system impairments requires broadening of the tools of rehabilitation. A promising opportunity for this purpose is the application of physiotherapy robots. The development of such devices goes back a quarter of century. Nowadays several robots are commercially available both for supporting upper and lower limb therapy. The aim is never to replace the therapists, but rather to support and supplement their work. It is worthwhile applying these devices for goal-oriented exercises in high repetition, which one physically fatiguing for the therapist or for the correction of functional movement by various strategies. Robot mediated therapy is also useful for motivation of the patient and making the rehabilitation programme more versatile. Robots can be used for assessment of the neuromotor status as well. Several clinical studies have been executed in this field, all over the world. Meta-analyses based on randomized, controlled trials show that supplementing the traditional physiotherapy with a robot-mediated component presents advantage for the patients. Further studies are necessary to clarify which modality and intensity of the exercises, in which group of patients, in which stage lead to the expected outcome.]

Clinical Neuroscience

[Genetically determined diseases associated with pathological brain iron accumulation and neurodegeneration]

ÁCS Péter, MOLNÁR Mária Judit, KLIVÉNYI Péter, KÁLMÁN Bernadette

[The rare, genetically determined group of diseases characterized by pathological accumulation of iron in the central nervous system and progressive, typically movement disorder’s symptoms are called NBIA (neurodegeneration with brain iron accumulation). By the rapid development of molecular genetics, it has become apparent that different mutations in numerous genes can lead to pathological cerebral iron accumulation. Simultaneously, it has also been recognized that the age of onset, the symptoms and the prognosis of NBIA disorders are much more diverse than it was previously perceived. To our knowledge, a review article on the most recent clinical data of NBIA has not been published in Hungarian. In the first part of this publication, we survey the general clinical characteristics and the diagnostic algorithm of NBIA diseases and address some considerations for differential diagnostics. In the second part of this review, the particular NBIA disorders are presented in details. The purpose of this article is to provide a clinical overview that may be useful for neurologists, pediatricians and any other medical practitioners interested in this field.]

All articles in the issue

Related contents

Clinical Neuroscience

The yield of electroencephalography in syncope

NALBANTOGLU Mecbure, TAN Ozturk Ozlem

Introduction - Syncope is defined as a brief transient loss of consciousness due to cerebral hypoperfusion. Although the diagnosis of syncope is based on a thorough history and examination, electroencaphalography (EEG) is also an important investigational tool in the differential diagnosis in this group of patients. In this study we aimed to identify the diagnostic value of EEG in patients with syncope. Methods - We retrospectively examined EEG recordings of 288 patients with the diagnosis of syncope referred to the Cankiri State Hospital EEG laboratory, from January 2014 to January 2016. The EEG findings were classified into 6 groups as normal, epileptiform discharges (spike and sharp waves), generalized background slowing, focal slowing, hemispherical asymmetries, and low amplitude EEG tracing. The EEGs were separated according to gender and age. Results - Total of 288 patients were included in this study, 148 were females (51.4%) and 140 (48.6%) were males. Among all the EEG reports, 203 (70.5%) were normal, 8 of them (2.8%) showed generalized background slowing and 7 (2.4%) demonstrated focal slow waves. Epileptiform discharges occured among 13 patients (4.5%). Hemispherical asymmetries were detected in 10 patients (3.5%) and low amplitude EEG tracing in 47 patients (16.3%). There was no significant difference between age groups in EEG findings (p=0.3). Also no significant difference was detected in EEG results by gender (p=0.2). Discussion - Although the diagnosis of syncope, epilepsy and non-epileptic seizures is clinical diagnosis, EEG still remains additional method

Clinical Neuroscience

[Diagnosis of epilepsy]


[0.5-1% of the population suffers from epilepsy, while another 5% undergoes diagnostic evaluations due to the possibility of epilepsy. In the case of suspected epileptic seizures we face the following questions: Is it an epileptic seizure? The main and most frequent differential- diagnostic problems are the psychogenic non-epileptic seizures ("pseudo-seizures") and the convulsive syncope, which is often caused by heart disorders. Is it epilepsy? After an unprovoked seizure, the information on recurrence risk is an important question. The reoccurrence is more possible if a known etiological factor is present or the EEG shows epileptiform discharges. After an isolated epileptic seizure, the EEG is specific to epilepsy in 30-50% of cases. The EEG should take place within 24 hours postictally. If the EEG shows no epileptiform potentials, a sleep-EEG is required. What is the cause of seizures? Hippocampal sclerosis, benign tumors, and malformations of the cortical development are the most frequent causes of the focal epilepsy. Three potentially life-threatening conditions may cause chronic epilepsy: vascular malformations, tumors, and neuroinfections. The diagnosis in theses cases can usually be achieved by MRI, therefore, MRI is obligatory in all epilepsies starting in adulthood. The presence of epileptogenic lesion has a prognostic significance in treatment. If the MRI shows a circumscribed lesion then the pharmacological treatment will likely to be unsuccessful, while surgery may result in seizure freedom. The new and quantitative MRI techniques, such as volumetry, T2-relaxometry, MR-spectroscopy, and functional MRI play a growing role in the epilepsy diagnosis.]

Clinical Neuroscience

[Spectral, phase-synchronization, and graph theoretical EEG changes related to mental arithmetics]

BOHA Roland, TÓTH Brigitta, GAÁL Zsófia Anna, KARDOS Zsófia, FILE Bálint, MOLNÁR Márk

[During mental arithmetic operations working memory playsan important role, but there are only few studies in which anattempt was made to separate this effect from the process ofarithmetics per se. In this study the effects of arithmetic onthe EEG of young adults (14 participants, six of themwomen, mean age 21.57 years, SD: 2.62) was investigatedduring a subtraction task in the θ(4-8 Hz) frequency band.Besides the power density spectrum analysis phasesynchrony based on recently developed graph theoreticalmethods were used and strength of local connections (clustercoefficient; C) and global interconnectedness of network(characteristic path length; L) were determined. Before thearithmetic task passive viewing (control situation) and anumber recognition paradigms were used. During the arith-metic task compared to the control situation significantlyincreasing phase synchrony and C values were found. L wassignificantly shorter (F(2, 26)=818.77, p<0.0001) only dur-ing the arithmetic task: this fact and the former two resultsimply that the network topology shifted towards the “smallworld” direction. Our findings concerning regionaldifferences confirm those reported earlier in the literature:compared to the control condition significant task-relatedincrease was found in C values in the parietal areas [moreexplicitly in the left side, (F(1, 13)=7.2020, p=0.0188)],which probably corresponds to stronger local connectionsand more synchronized (sub)networks. During the task con-dition significantly increased θband power; (F(1,13)=7.9708, p=0.0144) and decreased L values werefound in the left frontal region compared to the right side(F(1, 13)=6.0734, p=0.0284), which can also be interpret-ed as an indicator of optimized network topology ofinformation processing.]

Clinical Neuroscience

[EEG-based cerebral networks in 14 neurological disorders]

DÖMÖTÖR Johanna, CLEMENS Béla, CSÉPÁNY Tünde, EMRI Miklós, FOGARASI András, HOLLÓDY Katalin, PUSKÁS Szilvia, FEKETE Klára, KOVÁCS Attila, FEKETE István

[Background - Brain networks have not been systematically investigated yet in most neurological disorders. Purpose - To investigate EEG functional connectivity (EEGfC) networks in 14 neurological disorders. Patients - Potentially eligible patients were collected from clinical and EEG databases. All the available clinical data and EEG records were critically revised. All the patients who suffered of a single neurological disorder (out of the 14) and had a good quality EEG recording entered the study. Confoundig factors as comorbidity and CNS-active drug effects were eliminated as far as possible. EEG analysis - Three minutes of resting-state, waking EEG activity were selected for analysis. Current source density (CSD) values were computed for 2394 cortical voxels by Low Resolution Electromagnetic Tomography (LORETA). Thereafter, Pearson correlation coefficients were computed between all pairs of 23 cortical regions of interest (ROI) in each hemisphere (LORETA Source Correlation, LSC software). Computation was carried out for conventional EEG broad bands and very narrow bands (1 Hz bandwidth) between 1 and 25 Hz as well. Correlation coefficients of each group were statistically compared to our normative EEG (LSC) database by two-talied t-tests. Bonferroni-corrected p<0.05 values were accepted as statistically significant, and were graphically displayed as topographical networks. Results and conclusion - Group-specific networks were demonstrated. However, non-specific networks, charasteristic for most groups, were detected as well. Common finding were: decreased connectivity in the alpha band and increased connectivity in the delta, theta bands and upper-beta band. Decreased alpha-band connectivity presumably reflected primary lesional effects and on the other hand, non-specific vulnerability of “rich club connections”. Increased connectivity in the slow bands presumably indicated adaptive-compensatory activity of brain homeostasis. ]

Clinical Neuroscience

[Ageing and arithmetic performance - electrophysiological complexity-, and graph theoretical characteristics]

MOLNÁR Márk, BOHA Roland, BENYOVSZKY Máté, GAÁL Zsófia Anna, TÓTH Brigitta

[During the course of ageing the decline of cognitive performance, including attention and working memory processes - essential for arithmetic procedures - is well known. For the investigation of the neuronal mechanisms of these processes the application of methods capable of taking into account the high complexity of the nervous system, the role of nonlinear processes and network-properties of its constituents are necessary. As for the latter the recently realized small world network characteristics representing optimal conditions for information processing may be of particular importance. In the present study the spectral, complexity-, and network characteristics of the EEG recorded during performing an arithmetic task in a group of young (n=32, mean age 22.0 yrs) and elderly (n=19, mean age: 66.7 yrs) was analyzed. Heart rate and behavioral measures (number of mistakes, reaction time) were also investigated. The alpha2 band decreased in the young, while the delta band increased in the elderly in the task condition. The increased Omega-complexity observed in the elderly is probably caused by reduced interneuronal connectivity. “Small-world” network characteristics were found in the beta and delta bands although in the elderly the topology was closer to a random pattern. In the task condition the network features of the elderly subjects shifted more towards the small world pattern than those seen in the young indicating that for the elderly the mobilized effort for task completion was higher. In spite of this, the level of performance and the heart rate change observed in the elderly was lower than that seen in the young. The application of complexity-, and graph theoretical analysis appears to be a promising tool for the investigation of diseases of the nervous system characterized by diffuse pathology as in the case of as various types of dementias.]