Biology subjects

Pavlov, Y. G.

Publications and source records attributed to Pavlov, Y. G..

4 recordsLinked to original sources

bioRxiv2018

Aversive conditioning in oddball paradigm modulates multisensory integration, attention and emotional processing

The nature of cortical plasticity in the course of learning is one of the most intriguing questions of the modern cognitive neuroscience. Aversive conditioning is a type of associative learning produced by continuous pairing of neutral and aversive stimuli. Aversive conditioning and electroencephalography together provide a good framework for expanding our knowledge about fast learning-related cortical changes. In our experiment we tested a novel paradigm to study associative learning where aversive conditioning was combined with passive oddball. We employed conditioned auditory neutral stimuli and unconditioned aversive electrical shocks and used time-frequency, connectivity and event-related potentials (ERP) analyses to explore their interaction. First, we observed changes in the cortical activity in the form of conditioning-induced multisensory integration. The integration manifested itself in (1) desynchronization of lower beta activity in the contralateral to expected electrical shocks hemisphere and (2) enhanced functional connectivity between auditory and somatosensory cortex in the gamma frequency band. Second, we found a larger amplitude of P3a and the late posterior positivity (LPP) components of ERP to conditioned stimuli, which may be related to increased attentional and emotional significance of these stimuli. Our results reproduced and extended previous findings about multisensory integration in classical conditioning and demonstrated the improved discriminability of ERP responses through incorporation of the oddball paradigm in associative learning.

neuroscience↗

bioRxiv2018

A Signature of Passivity? An Explorative Study of the N3 Event-Related Potential Component in Passive Oddball Tasks

Many passive oddball experiments show a negative deflection N3 peaking between 400 and 500 ms, but this wave has never been analyzed properly. We conducted five passive oddball experiments, in which the number of deviants (i.e., one or two), their alleged meaning and their distinctiveness varied. Mastoid- or common-referenced waveforms showed a fronto-central N3 in all experiments. The data were CSD (Current Source Density) transformed and underwent a Principal Component Analysis (PCA). The PCA revealed N3 containing two subcomponents with very stable peak latencies of about 415 and 455 ms, respectively. Both topography of the subcomponents and their variation with experimental conditions were very similar but different from other negative ERP components N1 and N2. The two N3 subcomponents were maximally negative over midfrontal areas but positive over the parietal and particularly over the posterior temporal cortex. Both frontal negativity and posterior positivity exhibited clear oddball effects, i.e., they were larger to deviants than to standards. Positive components P3a and P3b were also analyzed, which replicated the previously known effects. In the Discussion, we speculate about possible meaning of N3; on this basis, specific hypotheses are formulated and further studies are suggested to test these hypotheses.

neuroscience↗

bioRxiv2017

Name Conditioning in Event-Related Brain Potentials

Four experiments are reported in which two harmonic tones (CS+ and CS-) were paired with a participants own name (SON) and different names (DN), respectively. A third tone was not paired with any other stimulus and served as a standard (frequent stimulus) in a three-stimuli oddball paradigm. The larger posterior positivity (P3) to SON than DN, found in previous studies, was replicated in all experiments. Conditioning of the P3 response was albeit observed in two similar experiments (1 and 3), but the obtained effects were weak and not identical in the two experiments. Only Experiment 4, where the number of CS/UCS pairings and the Stimulus-Onset Asynchrony between CS and UCS were increased, showed clear CS+/CS- differences both in time and time-frequency domains. Surprisingly, differential responses to CS+ and CS- were also obtained in Experiment 2, although SON and DN in that experiment were masked and never consciously recognized as meaning words (recognition rate 0/63 participants). The results are discussed in the context of other ERP conditioning experiments and, particularly, the studies of non-conscious effect on ERP. Several further experiments are suggested to replicate and extend the present findings and to remove the remaining methodological limitations.

neuroscience↗

bioRxiv2017

EEG correlates of working memory performance in females

BackgroundThe study investigates oscillatory brain activity during working memory (WM) tasks. The tasks employed varied in two dimensions. First, they differed in complexity from average to highly demanding. Second, we used two types of tasks, which required either only retention of stimulus set or retention and manipulation of the content. We expected to reveal EEG correlates of temporary storage and central executive components of WM and to assess their contribution to individual differences.\n\nResultsGenerally, as compared with the retention condition, manipulation of stimuli in WM was associated with distributed suppression of alpha1 activity and with the increase of the midline theta activity. Load and task dependent decrement of beta1 power was found during task performance. Beta2 power increased with the increasing WM load and did not significantly depend on the type of the task.\n\nAt the level of individual differences, we found that the high performance (HP) group was characterized by higher alpha rhythm power. The HP group demonstrated task-related increment of theta power in the left anterior area and a gradual increase of theta power at midline area. In contrast, the low performance (LP) group exhibited a drop of theta power in the most challenging condition. HP group was also characterized by stronger desynchronization of beta1 rhythm over the left posterior area in the manipulation condition. In this condition, beta2 power increased in the HP group over anterior areas, but in the LP group over posterior areas.\n\nConclusionsWM performance is accompanied by changes in EEG in a broad frequency range from theta to higher beta bands. The most pronounced differences in oscillatory activity between individuals with high and low WM performance can be observed in the most challenging WM task.

neuroscience↗