Karolina Janacsek

Both the cutaneous sensation and phosphene perception are modulated in a frequency-specific manner during transcranial alternating current stimulation

PURPOSEnTranscranial alternating current stimulation (tACS) is a non-invasive stimulation technique for shaping neuroplastic processes and possibly entraining ongoing neural oscillations in humans. Despite the growing number of studies using tACS, we know little about the procedural sensations caused by stimulation. In order to fill this gap, we explored the cutaneous sensation and phosphene perception during tACS.nnnMETHODSnTwenty healthy participants took part in a randomized, single-blinded, sham-controlled study, where volunteers received short duration stimulation at 1.0 mA intensity between 2 to 250 Hz using the standard left motor cortex-contralateral supraorbital montage. We recorded the perception onset latency and the strength of the sensations assessed by visual rating scale as dependent variables.nnnRESULTSnWe found that tACS evoked both cutaneous sensation and phosphene perception in a frequency-dependent manner. Our results show that the most perceptible procedural sensations were induced in the beta and gamma frequency range, especially at 20 Hz, whereas minimal procedural sensations were indicated in the ripple range (140 and 250 Hz).nnnCONCLUSIONSnWe believe that our results provide a relevant insight into the procedural sensations caused by oscillatory currents, and will offer a basis for developing more sophisticated stimulation protocols and study designs for future investigations.

Different strategies underlying uncertain decision making: higher executive performance is associated with enhanced feedback-related negativity.

The aim of the present study was to investigate the role of executive functions (EFs) in different strategies underlying risky decision making. Adult participants from a nonclinical sample were assigned to low or high EF groups based on their performance on EF tasks measuring shifting, updating, and inhibition. ERPs were recorded while participants performed the Balloon Analogue Risk Task (BART). In this task, each balloon pump was associated with either a reward or a balloon pop with unknown probability. The BART behavioral measures did not show between-group differences. However, the feedback-related negativity (FRN) associated with undesirable outcomes was larger in the high EF group than in the low EF group. Since the FRN represents salience prediction error, our results suggest that the high EF group formed internal models that were violated by the outcomes. Thus, we provided ERP evidence for EFs influencing risky decision-making processes.

Right Hemisphere Advantage in Statistical Learning: Evidence From a Probabilistic Sequence Learning Task

BACKGROUNDnPicking up statistical regularities of patterns from the environment is essential for predictive and adaptive behavior. One of the most important challenges is to understand how statistical learning occurs and how the acquired information consolidates and stabilizes in the brain. Evidence suggests that the prefrontal cortex (PFC) has a critical role in these processes; the division of labor between hemispheres, however, is less characterized.nnnOBJECTIVE/HYPOTHESISnThe aim of the present study was to directly investigate the causal role of the right and left PFC in statistical learning and its consolidation.nnnMETHODSnHealthy, young adults were trained on a probabilistic sequence learning task. Anodal transcranial direct current stimulation (tDCS) over the right or left dorsolateral PFC (DLPFC) was applied during the training in order to modify learning-related cortical plasticity in the targeted brain regions by increasing neural excitability. Performance was tested during and immediately after the stimulation, 2-h and 24-h later.nnnRESULTSnWe found that the anodal tDCS over the right DLPFC led to enhanced learning performance both after the 2-h and 24-h retention periods, suggesting the causal role of this area in statistical learning. In contrast, we did not find any effect of left DLPFC stimulation on learning.nnnCONCLUSIONSnThese results highlight the role of the right fronto-striatal network in statistical learning and its consolidation.

The Production of Nominal and Verbal Inflection in an Agglutinative Language: Evidence from Hungarian

The contrast between regular and irregular inflectional morphology has been useful in investigating the functional and neural architecture of language. However, most studies have examined the regular/irregular distinction in non-agglutinative Indo-European languages (primarily English) with relatively simple morphology. Additionally, the majority of research has focused on verbal rather than nominal inflectional morphology. The present study attempts to address these gaps by introducing both plural and past tense production tasks in Hungarian, an agglutinative non-Indo-European language with complex morphology. Here we report results on these tasks from healthy Hungarian native-speaking adults, in whom we examine regular and irregular nominal and verbal inflection in a within-subjects design. Regular and irregular nouns and verbs were stem on frequency, word length, and phonological structure, and both accuracy and response times were acquired. The results revealed that the regular/irregular contrast yields similar patterns in Hungarian, for both nominal and verbal inflection, as in previous studies of non-agglutinative Indo-European languages: the production of irregular inflected forms was both less accurate and slower than of regular forms, both for plural and past-tense inflection. The results replicate and extend previous findings to an agglutinative language with complex morphology. Together with previous studies, the evidence suggests that the regular/irregular distinction yields a basic behavioral pattern that holds across language families and linguistic typologies. Finally, the study sets the stage for further research examining the neurocognitive substrates of regular and irregular morphology in an agglutinative non-Indo-European language.

A végrehajtó funkciók és az implicit tanulás versengő kapcsolata

Jelen tanulmany kulonboző neurokognitiv folyamatok versengő kapcsolatat vizsgalja az implicit tanulas es a vegrehajto funkciok műkodesenek bemutatasan keresztul. Az implicit tanulasrol ma mar tudjuk, hogy — a vegrehajto funkciokat műkodtető frontalis teruletekkel atfedesben — a fronto-striatalis halozat műkodesen alapszik. Ez az atfedes egymassal kooperalo es kompetitiv folyamatokat is eredmenyezhet. Ket kognitiv folyamat versengő kapcsolatat tobbfele kiserleti elrendezesben is lehet vizsgalni, peldaul az egyik folyamat gyengitesevel vagy egy olyan vizsgalati populacio valasztasaval, amelyben az egyik vagy a masik funkcioert felelős agyi terulet serult. Jelen attekintő tanulmany celja, hogy az utobbi evekben megjelent, ezeket a modszereket hasznalo kutatasokon keresztul bemutassa az implicit tanulas es a vegrehajto funkciok kapcsolatat. A felsorakoztatott eredmenyek alapjan a frontalis lebeny fuggő vegrehajto funkciok es az implicit tanulas kozott negativ kapcsolat all fenn, tehat a gyengebb vegrehajto fu...