Publications by authors named "János Horváth"

76 Publications

Processing and utilization of auditory action effects in individual and social tasks.

Acta Psychol (Amst) 2021 Jun 11;217:103326. Epub 2021 May 11.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary; Institute of Psychology, Károli Gáspár University of the Reformed Church in Hungary, Budapest, Hungary.

The influence of action-effect integration on motor control and sensory processing is often investigated in arrangements featuring human-machine interactions. Such experiments focus on predictable sensory events produced through participants' interactions with simple response devices. Action-effect integration may, however, also occur when we interact with human partners. The current study examined the similarities and differences in perceptual and motor control processes related to generating sounds with or without the involvement of a human partner. We manipulated the complexity of the causal chain of events between the initial motor and the final sensory event. In the self-induced condition participants generated sounds directly by pressing a button, while in the interactive condition sounds resulted from a paired reaction-time task, that is, the final sound was generated indirectly, by relying on the contribution of the partner. Auditory event-related potentials (ERPs) and force application patterns were similar in the two conditions, suggesting that social action effects produced with the involvement of a second human agent in the causal sequence are processed, and utilized as action feedback in the same way as direct consequences of one's actions. The only reflection of a processing difference between the two conditions was a slow, posterior ERP waveform that started before the presentation of the auditory stimulus, which may reflect differences in stimulus expectancy or task difficulty.
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http://dx.doi.org/10.1016/j.actpsy.2021.103326DOI Listing
June 2021

Word class and word frequency in the MMN looking glass.

Brain Lang 2021 Jul 5;218:104964. Epub 2021 May 5.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary; Institute of Psychology, Károli Gáspár University of the Reformed Church in Hungary, Budapest, Hungary.

The effects of lexical meaning and lexical familiarity on auditory deviance detection were investigated by presenting oddball sequences of words, while participants ignored the stimuli. Stimulus sequences were composed of words that were varied in word class (nouns vs. functions words) and frequency of language use (high vs. low frequency) in a factorial design with the roles of frequently presented stimuli (Standards) and infrequently presented ones (Deviants) were fully crossed. Deviants elicited the Mismatch Negativity component of the event-related brain potential. Modulating effects of lexical meaning were obtained, revealing processing advantages for denotationally meaningful items. However, no effect of word frequency was observed. These results demonstrate that an apparently low-level function, such as auditory deviance detection utilizes information from the mental lexicon even for task-irrelevant stimuli.
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http://dx.doi.org/10.1016/j.bandl.2021.104964DOI Listing
July 2021

Action-related auditory ERP attenuation is not modulated by action effect relevance.

Biol Psychol 2021 04 5;161:108029. Epub 2021 Feb 5.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary; Károli Gáspár University of the Reformed Church in Hungary, Hungary.

Event-related potentials (ERPs) elicited by self-induced sounds are often smaller than ERPs elicited by identical, but externally generated sounds. This action-related auditory ERP attenuation is more pronounced when self-induced sounds are intermixed with similar sounds generated by an external source. The current study explored whether attentional factors contributed to this phenomenon. Participants performed tone-eliciting actions, while the action-tone contingency and the set of additional action effects (tactile only, tactile and visual) were manipulated in a blocked manner. Previous action-tone contingence-effects were replicated, but the addition of other sensory action consequences did not influence the magnitude of auditory ERP attenuation. This suggests that the amount of attention allocated to concurrent non-auditory action effects does not substantially affect the magnitude of action-related auditory ERP attenuation and is on a par with the assumption that action-related auditory ERP attenuation might be related to the process of distinguishing self-induced stimuli from externally generated ones.
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http://dx.doi.org/10.1016/j.biopsycho.2021.108029DOI Listing
April 2021

Insights into graphene oxide interaction with human serum albumin in isolated state and in blood plasma.

Int J Biol Macromol 2021 Apr 27;175:19-29. Epub 2021 Jan 27.

Institute of Biophysics, Biological Research Centre, H-6726 Szeged, Hungary.

The interactions of graphene oxide (GO), a 2-dimensional nanomaterial with hydrophilic edges, hydrophobic basal plane and large flat surfaces, with biological macromolecules, are of key importance for the development of novel nanomaterials for biomedical applications. To gain more insight into the interaction of GO flakes with human serum albumin (HSA), we examined GO binding to HSA in its isolated state and in blood plasma. Calorimetric data reveal that GO strongly stabilizes free isolated HSA against a thermal challenge at low ionic strength, indicating strong binding interactions, confirmed by the drop in ζ-potential of the HSA/GO assemblies compared to bare GO flakes. However, calorimetry also revealed that the HSA-GO molecular interaction is hampered in blood plasma, the ionic strength being particularly important for the interactions. Molecular modelling calculations are in full concert with these experimental findings, indicating a considerably higher binding affinity for HSA to GO in its partially unfolded state, characteristic to low-ionic-strength environment, than for the native protein conformation, observed under physiological conditions. Therefore, for the first time we demonstrate an impeded interaction between HSA and GO nanoflakes in blood plasma, and suggest that the protein is protected from the plausible toxic effects of GO under native conditions.
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http://dx.doi.org/10.1016/j.ijbiomac.2021.01.151DOI Listing
April 2021

Pre-attentive auditory change detection for rapid auditory transient combinations: Insight from age-related processing changes.

Biol Psychol 2021 02 15;159:108024. Epub 2021 Jan 15.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, H-1117, Budapest, Magyar Tudósok körútja 2, Hungary; Institute of Psychology, Károli Gáspár University of the Reformed Church in Hungary, H-1037, Budapest, Bécsi út 324, Hungary. Electronic address:

The N1 event-related potential (ERP) enhancement to auditory transients preceded briefly by another transient has been interpreted as a reflection of latent inhibition, or alternatively, as a superimposing mismatch negativity (MMN) to rare transient event combinations. In a previous study (Volosin, Gaál, & Horváth, 2017a), when rare glides preceded frequent gaps by 150 ms in continuous tones, gap-related N1 was enhanced in younger adults while P2 was attenuated both in younger and older adults, which could be parsimoniously explained by MMN overlap which was delayed with aging. The present study replicated and extended these results with a condition in which the roles of the two event types were reversed. Transients separated by 150 ms elicited delayed MMN in older adults, supporting the MMN interpretation over the latent inhibition account. Furthermore, the divergence of N1 and MMN elicitation patterns demonstrated the independence of N1 and MMN.
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http://dx.doi.org/10.1016/j.biopsycho.2021.108024DOI Listing
February 2021

Task difficulty modulates voluntary attention allocation, but not distraction in an auditory distraction paradigm.

Brain Res 2020 01 22;1727:146565. Epub 2019 Nov 22.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja 2, H-1117 Budapest, Hungary; Institute of Psychology, Károli Gáspár University of the Reformed Church in Hungary, Bécsi út 324, H-1037 Budapest, Hungary. Electronic address:

Keeping task-relevant sensory events in the focus of attention while ignoring irrelevant ones is crucial for optimizing task behavior. This attention-distraction balance might change with the perceptual demands of the ongoing task: while easy tasks might be performed with low attentional effort, difficult ones require enhanced attention. The goal of the present study was to investigate how task difficulty affected allocation of attention and distractibility in an auditory distraction paradigm. Participants performed a tone duration discrimination task in which tones were rarely, occasionally presented at a rare pitch (distracters), and task difficulty was manipulated by the duration difference between short and long tones. Short tones were consistently 200 ms long, while long tone duration was 400 ms in the easy, and 260 ms in the difficult condition. Behavioral results and deviant-minus-standard event-related potential (ERP) waveforms suggested similar magnitudes of distraction in both conditions. ERPs without such a subtraction showed that tone onsets were preceded by a negative-going trend, suggesting that participants prepared for tone onsets. In the difficult condition, N1 amplitudes to tone onsets were enhanced, indicating that participants invested more attentional resources. Increased difficulty also slowed down tone offset processing as reflected by significantly delayed offset-related P1 and N1/N2 waveforms. These results suggest that although task difficulty compels participants to attend the tones more strongly, this does not have significant impact on distraction-related processing.
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http://dx.doi.org/10.1016/j.brainres.2019.146565DOI Listing
January 2020

The role of auditory context in action-effect-related motor adaptation.

Hum Mov Sci 2019 Oct 31;67:102503. Epub 2019 Jul 31.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, P.O.B. 286, H-1519 Budapest, Hungary; Károli Gáspár University of the Reformed Church in Hungary, Kálvin tér 9., H-1091 Budapest, Hungary. Electronic address:

Previous research indicates that adding auditory effects to a (silent) action can lead to substantial efficiency gains in the performance of the action, while compromising the connection between the motor and the auditory event (e.g., by removing, or by delaying the auditory effects), leads the agent to compensate for the loss of auditory feedback by executing actions in a way which increases the probability of success or enhances feedback in other modalities, thus departing from the optimal action performance. The current study explored how this motor adaptation was affected when the quality of auditory feedback was reduced by contextual factors, while keeping the physical link between the action and auditory effect intact. In two experiments, participants elicited pure tones by pinching a force sensitive resistor (FSR). In some of the conditions action-effect contingency was reduced by intermixing externally initiated tones with the self-induced ones. Pinch-force measurements indicated that action optimization was affected by contextual factors. The influence of auditory context was the most pronounced when the discrimination of self-induced and external tones was made difficult by the similarity and temporal proximity of the self-induced and external tones. In these conditions, tone eliciting actions were more forceful in comparison to conditions in which no external tones were presented, and in comparison to conditions in which the external tones were easily distinguishable from self-induced ones. This suggests that contextual factors can induce similar motor adjustments as manipulating the physical connection between the action and its sensory consequences.
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http://dx.doi.org/10.1016/j.humov.2019.102503DOI Listing
October 2019

Temporal constraints in the use of auditory action effects for motor optimization.

J Exp Psychol Hum Percept Perform 2018 Nov 9;44(11):1815-1829. Epub 2018 Aug 9.

Institute of Cognitive Neuroscience and Psychology.

For quick ballistic movements the possibility of making online adjustments is limited. However, when the same action (e.g., pressing a button) is repeated multiple times, trial-by-trial adjustments are possible: Previous studies found that participants utilized auditory effects as feedback to optimize the applied force for such tone eliciting actions. In the current study, it was examined whether this also occurred if a delay was inserted between the action and its auditory effect. In 2 experiments, participants applied force impulses to a force-sensitive resistor in a self-paced schedule. Action-effect delay was manipulated between experimental blocks in the 0- to 1,600-ms range. The level of motor adaptation diminished as a function of action-effect delay, with no adaptation observable for delays longer than 200 ms, which indicates that action-effect contingency in itself is not sufficient to warrant that sensory effects will be useful for action control. A third experiment also showed that the observed temporal constraint was not absolute: Adaptation at 200-ms delay was stronger in a group of participants who were exposed to 400-ms action-tone delays before testing, than in a group exposed to a 0-ms action-tone delay, suggesting that action-effect-related motor adaptation is influenced by prior experience. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
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http://dx.doi.org/10.1037/xhp0000571DOI Listing
November 2018

Action-effect related motor adaptation in interactions with everyday devices.

Sci Rep 2018 04 26;8(1):6592. Epub 2018 Apr 26.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.

Human action planning relies on integrated representations of motor acts and the associated consequences, which implies that changing the set of effects associated to a motor act might directly influence action planning and control. The present study investigated the hypothesis that action-effect manipulations also affected the motor components of the actions even when only a single action option was available. Participants performed simple everyday actions (pinched a plastic sheet, pressed a button, tapped on a table) in two conditions. In the motor-auditory condition actions resulted in the presentation of a tone, whereas no tones were presented in the motor condition. The applied force was softer in the motor-auditory than in the motor condition for all three types of actions. The temporal characteristics of force application showed that action-effect related motor adaptation occurred during action planning, but possibly also during action execution. This demonstrates that even in simple, well-defined interactions with everyday devices we take all (even seemingly task-irrelevant) action-effects into account during action planning, which affects the motor component of the action. The results also imply that in experiments manipulating contingent action effects, one cannot rely on the assumption that the motor part of the action is invariant between conditions.
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http://dx.doi.org/10.1038/s41598-018-25161-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5920059PMC
April 2018

Plasma phospholipid profiling of a mouse model of anxiety disorder by hydrophilic interaction liquid chromatography coupled to high-resolution mass spectrometry.

Biomed Chromatogr 2018 Jun 5;32(6):e4202. Epub 2018 Mar 5.

Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Szeged, Hungary.

Glycerophospholipids (PLs), as amphipathic small molecules and the main constituents of biological membranes, play an important role in several cellular processes, even though their accurate identification from complex biological samples remains a challenge. In this paper, we report a fast and comprehensive HILIC-ESI-MS method for the analysis of glycerophospholipid classes using high-resolution mass spectrometry in negative mode. The final method enabled the quantitative analysis of 130 endogenous PL species in mouse plasma. The application of the method developed was to find differences of plasma PL composition in a mouse model of anxiety disorder. In the case of four PL classes and 35 PL species, significant differences were observed comparing low anxiety-related behavior with high anxiety-related behavior groups. The most characteristic trend was up-regulation in both the PL classes and PL species, and decreases were only detected in two phosphatidylcholines among 35 species in mice having elevated anxiety.
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http://dx.doi.org/10.1002/bmc.4202DOI Listing
June 2018

The detection of higher-order acoustic transitions is reflected in the N1 ERP.

Psychophysiology 2018 07 30;55(7):e13063. Epub 2018 Jan 30.

Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary.

The auditory system features various types of dedicated change detectors enabling the rapid parsing of auditory stimulation into distinct events. The activity of such detectors is reflected by the N1 ERP. Interestingly, certain acoustic transitions show an asymmetric N1 elicitation pattern: whereas first-order transitions (e.g., a change from a segment of constant frequency to a frequency glide [c-to-g change]) elicit N1, higher-order transitions (e.g., glide-to-constant [g-to-c] changes) do not. Consensus attributes this asymmetry to the absence of any available sensory mechanism that is able to rapidly detect higher-order changes. In contrast, our study provides compelling evidence for such a mechanism. We collected electrophysiological and behavioral data in a transient-detection paradigm. In each condition, a random (50%-50%) sequence of two types of tones occurred, which did or did not contain a transition (e.g., c-to-g and constant stimuli or g-to-c and glide tones). Additionally, the rate of pitch change of the glide varied (i.e., 10 vs. 40 semitones per second) in order to increase the number of responding neural assemblies. The rate manipulation modulated transient ERPs and behavioral detection performance for g-to-c transitions much stronger than for c-to-g transitions. The topographic and tomographic analyses suggest that the N1 response to c-to-g and also to g-to-c transitions emerged from the superior temporal gyrus. This strongly supports a sensory mechanism that allows the fast detection of higher-order changes.
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http://dx.doi.org/10.1111/psyp.13063DOI Listing
July 2018

Comprehensive phospholipid and sphingomyelin profiling of different brain regions in mouse model of anxiety disorder using online two-dimensional (HILIC/RP)-LC/MS method.

J Pharm Biomed Anal 2018 Feb 8;149:308-317. Epub 2017 Nov 8.

Department of Medical Chemistry, Faculty of Medicine, University of Szeged Dóm tér 8, H-6720, Szeged, Hungary.

A novel online system including two-dimensional liquid chromatography coupled to high-resolution mass spectrometry (2D-LC/MS) was developed and applied for comprehensive phospholipid (PL) and sphingomyelin (SM) profiling of dorsal hippocampus (DHPC), ventral (VHPC) and prefrontal cortex (PFC) brain regions in a mouse model of anxiety disorder. In the first dimension, lipid classes were distinguished by hydrophilic interaction liquid chromatography (HILIC), while the second dimensional separation of individual PL and SM species was achieved by reversed-phase (RP) chromatography. For the enrichment of lipid species in diluted HILIC effluent, two RP trapping columns were used separately. The developed fully-automated 2D method allowed the quantitative analysis of over 150 endogenous PL and SM species in mouse brain regions within 40min. The developed method was applied in a pilot study, which aimed to find alteration of PL and SM composition in a mouse model of anxiety disorder. In the case of 37 PL and SM species, significant differences were observed between high anxiety-related behavior (AX) and low anxiety-related behavior (nAX) mice. In mice having elevated anxiety, the most typical trend was the downregulation of PL species, in particular, in VHPC.
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http://dx.doi.org/10.1016/j.jpba.2017.10.043DOI Listing
February 2018

Age-related processing delay reveals cause of apparent sensory excitability following auditory stimulation.

Sci Rep 2017 08 31;7(1):10143. Epub 2017 Aug 31.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, H-1117, Magyar Tudósok körútja 2., Hungary.

When background auditory events lead to enhanced auditory event-related potentials (ERPs) for closely following sounds, this is generally interpreted as a transient increase in the responsiveness of the auditory system. We measured ERPs elicited by irrelevant probes (gaps in a continuous tone) at several time-points following rare auditory events (pitch glides) in younger and older adults, who watched movies during stimulation. Fitting previous results, in younger adults, gaps elicited increasing N1 auditory ERPs with decreasing glide-gap separation. N1 increase was paralleled by an ERP decrease in the P2 interval. In older adults, only a glide-gap separation dependent P2 decrease, but no N1-effect was observable. This ERP pattern was likely caused by a fronto-central negative waveform, which was delayed in the older adult group, thus overlapping N1 and P2 in the younger, but overlapping only P2 in the older adult group. Because the waveform exhibited a polarity reversal at the mastoids, it was identified as a mismatch negativity (MMN). This interpretation also fits previous studies showing that gap-related MMN is delayed in older adults, reflecting an age-related deterioration of fine temporal auditory resolution. These results provide a plausible alternative explanation for the ERP enhancement for sounds following background auditory events.
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http://dx.doi.org/10.1038/s41598-017-10696-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579239PMC
August 2017

Sound offset-related brain potentials show retained sensory processing, but increased cognitive control activity in older adults.

Neurobiol Aging 2017 09 6;57:232-246. Epub 2017 Jun 6.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary; Eötvös Loránd University, Faculty of Education and Psychology, Budapest, Hungary; University of Leipzig, Cognitive and Biological Psychology, Leipzig, Germany.

It has been hypothesized that age-related hearing loss is caused not only by peripheral but also central changes in the auditory system. Many studies used event-related potentials (ERPs) elicited by sound onsets to characterize the age-related differences in central auditory processing. Age-related ERP enhancements in such studies have often been interpreted in terms of elevated sensitivity to auditory stimulation. Such ERPs, however, comprise various components reflecting different aspects of auditory and task-related processing. The composition of the waveforms may considerably differ for ERPs elicited by other auditory events. In the present study, ERPs elicited by tone offsets were used to characterize processing differences between younger and older adults in a short-go, tone-duration discrimination paradigm. Whereas the onset-related auditory ERP was enhanced in the older adult group, no age-related differences were found in the offset-related auditory ERPs observable at temporal electrodes. In older adults, however, offset-related processing was dominated by an N2 that could reflect enhanced cognitive control activities. Because N2 was present regardless discrimination difficulty, younger adults may have framed the task as offset detection, whereas older adults represented the task as "genuine" discrimination.
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http://dx.doi.org/10.1016/j.neurobiolaging.2017.05.026DOI Listing
September 2017

Task-optimal auditory attention set restored as fast in older as in younger adults after distraction.

Biol Psychol 2017 05 12;126:71-81. Epub 2017 Apr 12.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja 2, H-1117 Budapest, Hungary. Electronic address:

The present study investigated how fast younger and older adults recovered from a distracted attentional state induced by rare, unpredictable sound events. The attentional state was characterized by the auditory N1 event-related potential (ERP), which is enhanced for sound events in the focus of attention. Younger (19-26 years) and older (62-74 years) adults listened to continuous tones containing rare pitch changes (glides) and short gaps. Glides and gaps could be separated in 150ms, 250ms, 650ms or longer and the task was gap detection while ignoring glides. With longer glide-gap separations similar N1 enhancements were observable in both groups suggesting that the duration of the distracted sensory state was not affected by aging. Older adults responded, however, slower at short glide-gap separations which indicated that distraction at subsequent levels of processing may have nonetheless more impact in older than in younger adults.
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http://dx.doi.org/10.1016/j.biopsycho.2017.04.007DOI Listing
May 2017

Consequences matter: Self-induced tones are used as feedback to optimize tone-eliciting actions.

Psychophysiology 2017 06 27;54(6):904-915. Epub 2017 Feb 27.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.

Experimental paradigms investigating the processing of self-induced stimuli are often based on the implicit assumption that motor processes are invariable regardless of their consequences: It is presumed that actions with different sets of predictable sensory consequences do not differ in their physical characteristics or in their brain signal reflections. The present experiment explored this assumption in the context of action-related auditory attenuation by comparing actions (pinches) with and without auditory consequences. The results show that motor processes are not invariable: Pinches eliciting a tone were softer than pinches without auditory effects. This indicates that self-induced auditory stimuli are not perceived as irrelevant side effects: The tones are used as feedback to optimize the tone-eliciting actions. The comparison of ERPs related to actions with different physical parameters (strong and soft pinches) revealed a significant ERP difference in the time range of the action-related N1 attenuation (strong pinches resulted in more negative amplitudes), suggesting that a motor correction bias may contribute to this auditory ERP attenuation effect, which is usually attributed to action-related predictive processes.
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http://dx.doi.org/10.1111/psyp.12845DOI Listing
June 2017

Characterizing the structural and folding properties of long-sequence hypomurocin B peptides and their analogs.

Biopolymers 2016 Sep;106(5):645-57

Hungarian Academy of Sciences, Institute of Biophysics, Biological Research Centre, Temesvári Krt. 62, Szeged, H-6726, Hungary.

We studied the folding processes of long-sequence hypomurocin (HM) peptides and their analogs by means of molecular dynamics methods, focusing on the formation of various helical structures and intramolecular H-bonds. The evolution of different helical conformations, such as the 310 -, α-, and left-handed α-helices, was examined, taking into account the entire sequence and each amino acid of peptides. The results indicated that the HM peptides and their analogs possessed a propensity to adopt helical conformations, and they showed a preference for the 310 -helical structure over the α-helical one. The evolution of a variety of the intramolecular H-bonds, including local and non-local interactions, was also investigated. The results pointed out that on the one hand, the appearance of local, helix-stabilizing H-bonds correlated with the presence of helical conformations, and on the other hand, the non-local H-bonds did not affect significantly the formation of helical structures. Additionally, comparing the structural and folding features of HM peptides and their analogs, our study led to the observation that the L-D isomerism of isovaline amino acid induced effects on the folding processes of these long-sequence peptaibol molecules. Accordingly, the HM peptides and their analogs could be characterized by typical structural and folding properties. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 645-657, 2016.
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http://dx.doi.org/10.1002/bip.22870DOI Listing
September 2016

Electrophysiological alterations in a complex rat model of schizophrenia.

Behav Brain Res 2016 07 30;307:65-72. Epub 2016 Mar 30.

Department of Physiology, Faculty of Medicine, University of Szeged, Dóm tér 10., H-6720 Szeged, Hungary. Electronic address:

Background: Psychiatric disorders are frequently accompanied by changes in brain electrical oscillations and abnormal auditory event related potentials. The goal of this study was to characterize these parameters of a new rat substrain showing several alterations related to schizophrenia.

Methods: Male rats of the new substrain, developed by selective breeding after combined subchronic ketamine treatment and postweaning social isolation, and naive Wistar ones group-housed without any interventions were involved in the present study. At the age of 3 months, animals were implanted with cortical electroencephalography electrodes. Auditory evoked potentials during paired-click stimuli and power of oscillation in different frequency bands were determined with and without acute ketamine (20mg/kg) treatment.

Results: Regarding the auditory evoked potentials, the latency of P2 was delayed and the amplitude of N1 peak was lower in the new substrain. The new substrain showed increased power of oscillations in the theta, alpha and beta bands, while decreased power was detected in delta and gamma2 bands (52-70Hz) compared with control animals. Acute ketamine treatment increased the gamma1 band (30-48Hz) power in both groups, while it elicited significant changes only in the new substrain in the total power and in alpha, beta and gamma2 bands.

Conclusions: The validation of the translational utility of this new rat substrain by electrophysiological investigations revealed that these rats show abnormalities that may model a part of the neurophysiological deficits observed in schizophrenia.
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http://dx.doi.org/10.1016/j.bbr.2016.03.051DOI Listing
July 2016

Exploiting temporal predictability: Event-related potential correlates of task-supportive temporal cue processing in auditory distraction.

Brain Res 2016 05 3;1639:120-31. Epub 2016 Mar 3.

Hungarian Academy of Sciences, Research Centre for Natural Sciences, Institute of Cognitive Neuroscience and Psychology, Magyar Tudósok körútja 2, H-1117 Budapest, Hungary. Electronic address:

The human cognitive system has various functions to enhance performance in tasks requiring responses to stimuli. When potentially occurring stimuli are known, we can establish selective attention sets and ignore task-irrelevant events while attending task-relevant ones. When the stimulation is temporally structured, we can rely on constant temporal relationships between stimulus events to prepare for the task-relevant moments. Most distraction paradigms feature task-irrelevant events which are followed by task-relevant ones within a constant interval, and distraction is induced by randomly replacing some of the standard task-irrelevant events. The constant time interval transforms irrelevant events to task-supportive temporal cues, which are integrated into the task-behavior by the participants. The present study investigated whether distracters could be utilized as temporal cues to support task-related processing in a continuous auditory stimulation paradigm. A continuous tone featuring short and long gaps, and pitch glides was presented. Participants performed a gap duration discrimination task, while ignoring glides. Glides could be presented frequently or rarely. In the informative condition, 80% of the glides predicted the presentation time of the forthcoming gap (400ms), while in the uninformative condition, the occurrence of gaps and glides was independent. Rare glides elicited an enhanced N1, mismatch negativity, and P3 event-related potentials in both informative and uninformative conditions. In informative conditions glides were followed by a contingent negative variation; and rare informative glides elicited an N2b, suggesting that despite triggering distraction-related processes, distracters could be integrated into the task-behavior, and could be utilized as task-supportive cues.
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http://dx.doi.org/10.1016/j.brainres.2016.02.044DOI Listing
May 2016

Attention-dependent sound offset-related brain potentials.

Authors:
János Horváth

Psychophysiology 2016 May 12;53(5):663-77. Epub 2016 Jan 12.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.

When performing sensory tasks, knowing the potentially occurring goal-relevant and irrelevant stimulus events allows the establishment of selective attention sets, which result in enhanced sensory processing of goal-relevant events. In the auditory modality, such enhancements are reflected in the increased amplitude of the N1 ERP elicited by the onsets of task-relevant sounds. It has been recently suggested that ERPs to task-relevant sound offsets are similarly enhanced in a tone-focused state in comparison to a distracted one. The goal of the present study was to explore the influence of attention on ERPs elicited by sound offsets. ERPs elicited by tones in a duration-discrimination task were compared to ERPs elicited by the same tones in not-tone-focused attentional setting. Tone offsets elicited a consistent, attention-dependent biphasic (positive-negative--P1-N1) ERP waveform for tone durations ranging from 150 to 450 ms. The evidence, however, did not support the notion that the offset-related ERPs reflected an offset-specific attention set: The offset-related ERPs elicited in a duration-discrimination condition (in which offsets were task relevant) did not significantly differ from those elicited in a pitch-discrimination condition (in which the offsets were task irrelevant). Although an N2 reflecting the processing of offsets in task-related terms contributed to the observed waveform, this contribution was separable from the offset-related P1 and N1. The results demonstrate that when tones are attended, offset-related ERPs may substantially overlap endogenous ERP activity in the postoffset interval irrespective of tone duration, and attention differences may cause ERP differences in such postoffset intervals.
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http://dx.doi.org/10.1111/psyp.12607DOI Listing
May 2016

Studying the structural and folding features of long-sequence trichobrachin peptides.

Chem Biodivers 2015 Sep;12(9):1365-77

Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, HU-6726 Szeged, (phone: +36-62-599726; fax: +36-62-433133).

In this theoretical study, the folding processes of long-sequence trichobrachin peptides (i.e., TB IIb peptides) were investigated by molecular dynamics methods. The formation of various helical structures (i.e., 310 -, α-, and left-handed α-helices) was studied with regard to the entire sequence of peptides, as well as to each amino acid. The results pointed out that TB IIb molecules showed a propensity to form helical conformations, and they could be characterized by 310 -helical structure rather than by α-helical structure. The formation of local (i.e., i←i+3 and i←i+4) as well as of non-local (i.e., i←i+n, where n>4; and all i→i+n) H-bonds was also examined. The results revealed that the occurrence of local, helix-stabilizing H-bonds was in agreement with the appearance of helical conformations, and the non-local H-bonds did not produce relevant effects on the evolution of helical structures. Based on the data obtained by our structural investigation, differences were observed between the TB IIb peptides, according to the type of amino acid located in the 17th position of their sequences. In summary, the folding processes were explored for TB IIb molecules, and our theoretical study led to the conclusion that these long-sequence peptaibols showed characteristic structural and folding features.
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http://dx.doi.org/10.1002/cbdv.201400280DOI Listing
September 2015

[The tip of the iceberg: multiple cutaneous sebaceous tumor in colon cancer. Muir-Torre syndrome--case report].

Orv Hetil 2015 Jun;156(24):979-84

Belgyógyászati Osztály, Zala Megyei Kórház Zalaegerszeg, Zrínyi u. 1., 8900.

Muir-Torre syndrome is a rare genodermatosis with autosomal dominant inheritance. The syndrome is considered to be a subtype of the hereditary nonpolyposis colorectal cancer (or Lynch-syndrome). In two-third of the cases, it develops as the consequence of germline mutations in mismatch-repair genes--most commonly MutS Homolog-2 and MutL Homolog-1. Its diagnosis can be established if at least one sebaceous tumor (sebaceoma, sebaceous adenoma, epithelioma, carcinoma or basal-cell carcinoma with sebaceous differentiation) and/or keratoacanthoma and at least one internal neoplasm are present. Here the authors present the history of a 52-year-old man with multiple sebaceous carcinomas on his back. Immunohistochemical analysis showed the lack of MutL Homolog-1 protein expression in the tumor cells. Detailed clinical workup in order to identify internal malignancy found malignant coecum tumor. Histopathological evaluation of the sample from the right hemicolectomy revealed mid-grade adenocarcinoma with MutL Homolog-1 and postmeiotic segregation increased-2 deficiency. The detection of the cutaneous sebaceous carcinoma and the application of the modern diagnostic methods resulted in identification of the associated colorectal cancer in an early stage; hence, definitive treatment was available for the patient.
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http://dx.doi.org/10.1556/650.2015.30165DOI Listing
June 2015

Anxious and nonanxious mice show similar hippocampal sensory evoked oscillations under urethane anesthesia: difference in the effect of buspirone.

Neural Plast 2015 9;2015:186323. Epub 2015 Apr 9.

Biological Research Centre, Hungarian Academy of Sciences, Temesvari Körút 32, Szeged 6726, Hungary.

Hippocampal oscillations recorded under urethane anesthesia are proposed to be modulated by anxiolytics. All classes of clinically effective anxiolytics were reported to decrease the frequency of urethane theta; however, recent findings raise concerns about the direct correlation of anxiolysis and the frequency of hippocampal theta. Here, we took advantage of our two inbred mouse strains displaying extremes of anxiety (anxious (AX) and nonanxious (nAX)) to compare the properties of hippocampal activity and to test the effect of an anxiolytic drugs. No difference was observed in the peak frequency or in the peak power between AX and nAX strains. Buspirone (Bus) applied in 2.5 mg/kg decreased anxiety of AX but did not have any effect on nAX as was tested by elevated plus maze and open field. Interestingly, Bus treatment increased hippocampal oscillatory frequency in the AX but left it unaltered in nAX mice. Saline injection did not have any effect on the oscillation. Paired-pulse facilitation was enhanced by Bus in the nAX, but not in the AX strain. Collectively, these results do not support the hypothesis that hippocampal activity under urethane may serve as a marker for potential anxiolytic drugs. Moreover, we could not confirm the decrease of frequency after anxiolytic treatment.
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http://dx.doi.org/10.1155/2015/186323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4408632PMC
November 2015

Action-related auditory ERP attenuation: Paradigms and hypotheses.

Authors:
János Horváth

Brain Res 2015 Nov 2;1626:54-65. Epub 2015 Apr 2.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, HAS, P.O.B. 286, H-1519 Budapest, Hungary. Electronic address:

A number studies have shown that the auditory N1 event-related potential (ERP) is attenuated when elicited by self-induced or self-generated sounds. Because N1 is a correlate of auditory feature- and event-detection, it was generally assumed that N1-attenuation reflected the cancellation of auditory re-afference, enabled by the internal forward modeling of the predictable sensory consequences of the given action. Focusing on paradigms utilizing non-speech actions, the present review summarizes recent progress on action-related auditory attenuation. Following a critical analysis of the most widely used, contingent paradigm, two further hypotheses on the possible causes of action-related auditory ERP attenuation are presented. The attention hypotheses suggest that auditory ERP attenuation is brought about by a temporary division of attention between the action and the auditory stimulation. The pre-activation hypothesis suggests that the attenuation is caused by the activation of a sensory template during the initiation of the action, which interferes with the incoming stimulation. Although each hypothesis can account for a number of findings, none of them can accommodate the whole spectrum of results. It is suggested that a better understanding of auditory ERP attenuation phenomena could be achieved by systematic investigations of the types of actions, the degree of action-effect contingency, and the temporal characteristics of action-effect contingency representation-buildup and -deactivation. This article is part of a Special Issue entitled SI: Prediction and Attention.
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http://dx.doi.org/10.1016/j.brainres.2015.03.038DOI Listing
November 2015

In silico conformational analysis of the short-sequence hypomurocin a peptides.

Int J Pept 2015 28;2015:281065. Epub 2015 Jan 28.

Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári Körút 62, Szeged 6726, Hungary ; Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Közép Fasor 52, Szeged 6726, Hungary.

In this theoretical study, a conformational analysis was performed on short-sequence hypomurocin A peptides, in order to identify their characteristic structural properties. For each hypomurocin A molecule, not only the backbone conformations, but also the side-chain conformations were examined. The results indicated that certain tetrapeptide units could be characterized by types I and III β-turn structures, and considering the helical conformations, it could be concluded that the hypomurocin A peptides showed a preference for the 310-helical structure over the α-helical structure. Beside the backbone conformations, the side-chain conformations were investigated, and the preferred rotamer states of the side-chains of amino acids were determined. Furthermore, the occurrence of i ← i + 3 and i ← i + 4 intramolecular H-bonds was studied, which could play a role in the structural stabilization of β-turns and helical conformations. On the whole, our theoretical study supplied a comprehensive characterization of the three-dimensional structure of short-sequence hypomurocin A peptides.
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http://dx.doi.org/10.1155/2015/281065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4324929PMC
February 2015

Simultaneous changes of spatial memory and spine density after intrahippocampal administration of fibrillar aβ1-42 to the rat brain.

Biomed Res Int 2014 23;2014:345305. Epub 2014 Jun 23.

Department of Medical Chemistry, University of Szeged, Dóm tér 8, Szeged 6720, Hungary.

Several animal models of Alzheimer's disease have been used in laboratory experiments. Intrahippocampal injection of fibrillar amyloid-beta (fAβ) peptide represents one of the most frequently used models, mimicking Aβ deposits in the brain. In our experiment synthetic fAβ1-42 peptide was administered to rat hippocampus. The effect of the Aβ peptide on spatial memory and dendritic spine density was studied. The fAβ1-42-treated rats showed decreased spatial learning ability measured in Morris water maze (MWM). Simultaneously, fAβ1-42 caused a significant reduction of the dendritic spine density in the rat hippocampus CA1 region. The decrease of learning ability and the loss of spine density were in good correlation. Our results prove that both methods (MWM and dendritic spine density measurement) are suitable for studying Aβ-triggered neurodegeneration processes.
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http://dx.doi.org/10.1155/2014/345305DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4094878PMC
March 2015

Detection by HPLC and structural characterization by NMR and MS of a natural deuterium isotopologue of ulipristal acetate.

J Pharm Biomed Anal 2014 Sep 7;98:279-86. Epub 2014 Jun 7.

API Research and Development, Spectroscopic Research, Gedeon Richter Plc., Gyömrői u. 19-21., H-1475 Budapest, Hungary. Electronic address:

Herein we discuss the structure elucidation of an unknown peak detected by HPLC in the active pharmaceutical ingredient ulipristal acetate during analytical method development. An extensive chromatographic, MS and NMR spectroscopic study gave the surprising result that the detected component is the natural-abundance mono-deuterium isotopologue of the API. To the best of our knowledge this is the first example where such a mono-deuterium isotopologue could be resolved from its mother component by HPLC and structurally fully characterized by NMR and MS. The reason for this separation could be rationalized in terms of some special structural features of the molecule.
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http://dx.doi.org/10.1016/j.jpba.2014.06.003DOI Listing
September 2014

The role of mechanical impact in action-related auditory attenuation.

Authors:
János Horváth

Cogn Affect Behav Neurosci 2014 Dec;14(4):1392-406

Research Centre for Natural Sciences, Hungarian Academy of Sciences, Institute of Cognitive Neuroscience and Psychology, P.O.B. 286, 1519, Budapest, Hungary,

A number of studies have shown that sounds temporally close to one's own finger movements elicit lower-amplitude auditory event-related potentials (ERPs) than do the same tones when they are only listened to. In these studies, the actions have involved making a mechanical contact with an object. In the present study, the role of mechanical contact with an object was investigated in action-related auditory attenuation. In three experiments, participants performed a time-interval production task. In each experiment, in one condition the action involved touching an object, but no mechanical contact was made in the other. The estimated tone-related ERP contributions to the action-tone coincidence ERP waveforms (calculated by subtracting the action-related ERP from the coincidence ERP) were more attenuated when the action involved moving the finger and making a mechanical contact at the end of the movement. However, when participants kept their finger on a piezoelectric element and applied pressure impulses without moving their finger, the action did not result in stronger attenuation of the tone-related auditory ERP estimates. Although these results may suggest that auditory ERP attenuation is stronger for actions resulting in mechanical impact, they also imply that mechanical impact may confound and lead to the overestimation of auditory ERP attenuation in such paradigms, because the impact may result in faint but audible sounds.
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http://dx.doi.org/10.3758/s13415-014-0283-xDOI Listing
December 2014

Knowledge of sequence structure prevents auditory distraction: an ERP study.

Int J Psychophysiol 2014 Jun 21;92(3):93-8. Epub 2014 Mar 21.

Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary. Electronic address:

Infrequent, salient stimuli often capture attention despite their task-irrelevancy, and disrupt on-going goal-directed behavior. A number of studies show that presenting cues signaling forthcoming deviants reduces distraction, which may be a "by-product" of cue-processing interference or the result of direct preparatory processes for the forthcoming distracter. In the present study, instead of "bursts" of cue information, information on the temporal structure of the stimulus sequence was provided. Young adults performed a spatial discrimination task where complex tones moving left or right were presented. In the predictable condition, every 7th tone was a pitch-deviant, while in the random condition the position of deviants was random with a probability of 1/7. Whereas the early event-related potential correlates of deviance-processing (N1 and MMN) were unaffected by predictability, P3a amplitude was significantly reduced in the predictable condition, indicating that prevention of distraction was based on the knowledge about the temporal structure of the stimulus sequence.
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http://dx.doi.org/10.1016/j.ijpsycho.2014.03.003DOI Listing
June 2014

Probing the sensory effects of involuntary attention change by ERPs to auditory transients.

Authors:
János Horváth

Psychophysiology 2014 May 26;51(5):489-97. Epub 2014 Feb 26.

Institute of Cognitive Neuroscience and Psychology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary.

An auditory selective attention set allows one to enhance the processing of goal-relevant sound events, which is reflected by the enhancement of the N1 event-related potential (ERP). The present study investigated whether the sensory consequences of distraction (i.e., involuntary attention changes triggered by infrequent sensory events) can be revealed as the removal of this attentional ERP enhancement. Continuous tones featuring occasional gaps were presented, and participants performed a gap-detection task. Independently from gaps, abrupt pitch changes (glides) were introduced, either rarely or frequently, in separate conditions. Whereas rare glides preceding gaps by 150 ms strongly impacted gap-detection performance and gap-related N1 amplitudes, their impact on gaps following rare glides by 650 ms was significantly smaller in both measures. This result demonstrates the utility of N1 in probing the sensory impact of auditory distraction.
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http://dx.doi.org/10.1111/psyp.12187DOI Listing
May 2014