Slow Wave Components Research Articles

Maternal oral probiotic use is associated with decreased breastmilk inflammatory markers, infant fecal microbiome variation, and altered recognition memory responses in infants-a pilot observational study.

Early life gut microbiomes are important for brain and immune system development in animal models. Probiotic use has been proposed as a strategy to promote health via modulation of microbiomes. In this observational study, we explore if early life exposure to probiotics via the mother during pregnancy and lactation, is associated with decreased inflammation in breastmilk, maternal and infant microbiome variation, and altered infant neurodevelopmental features. Exclusively breastfeeding mother-infant dyads were recruited as part of the "Mothers and Infants Linked for Healthy Growth (MILk) Study." Probiotic comparison groups were defined by exposure to maternal probiotics (NO/YES) and by timing of probiotic exposure (prenatal, postnatal, total). C-reactive protein (CRP) and IL-6 levels were determined in breastmilk by immunoassays, and microbiomes were characterized from 1-month milk and from 1- and 6-month infant feces by 16S rDNA sequencing. Infant brain function was profiled via electroencephalogram (EEG); we assessed recognition memory using event-related potential (ERP) responses to familiar and novel auditory (1 month) and visual (6 months) stimuli. Statistical comparisons of study outcomes between probiotic groups were performed using permutational analysis of variance (PERMANOVA) (microbiome) and linear models (all other study outcomes), including relevant covariables as indicated. We observed associations between probiotic exposure and lower breastmilk CRP and IL-6 levels, and infant gut microbiome variation at 1- and 6-months of age (including higher abundances of Bifidobacteria and Lactobacillus). In addition, maternal probiotic exposure was associated with differences in infant ERP features at 6-months of age. Specifically, infants who were exposed to postnatal maternal probiotics (between the 1- and 6-month study visits) via breastfeeding/breastmilk, had larger differential responses between familiar and novel visual stimuli with respect to the late slow wave component of the EEG, which may indicate greater memory updating potential. The milk of mothers of this subgroup of infants had lower IL-6 levels and infants had different 6-month fecal microbiomes as compared to those in the "NO" maternal probiotics group. These results support continued research into "Microbiota-Gut-Brain" connections during early life and the role of pre- and postnatal probiotics in mothers to promote healthy microbiome-associated outcomes in infants.

Novel murine closed-loop auditory stimulation paradigm elicits macrostructural sleep benefits in neurodegeneration.

Boosting slow-wave activity (SWA) by modulating slow waves through closed-loop auditory stimulation (CLAS) might provide a powerful non-pharmacological tool to investigate the link between sleep and neurodegeneration. Here, we established mouse CLAS (mCLAS)-mediated SWA enhancement and explored its effects on sleep deficits in neurodegeneration, by targeting the up-phase of slow waves in mouse models of Alzheimer's disease (AD, Tg2576) and Parkinson's disease (PD, M83). We found that tracking a 2 Hz component of slow waves leads to highest precision of non-rapid eye movement (NREM) sleep detection in mice, and that its combination with a 30° up-phase target produces a significant 15-30% SWA increase from baseline in wild-type (WTAD)and transgenic (TGAD) mice versus a mock stimulation group. Conversely, combining 2 Hz with a 40° phase target yields a significant increase ranging 30-35% in WTPD and TGPD mice. Interestingly, these phase-target-triggered SWA increases are not genotype dependent but strain specific. Sleep alterations that may contribute to disease progression and burden were described in AD and PD lines. Notably, pathological sleep traits were rescued by mCLAS, which elicited a 14% decrease of pathologically heightened NREM sleep fragmentation in TGAD mice, accompanied by a steep decrease in microarousal events during both light and dark periods. Overall, our results indicate that model-tailored phase targeting is key to modulate SWA through mCLAS, prompting the acute alleviation of key neurodegeneration-associated sleep phenotypes and potentiating sleep regulation and consolidation. Further experiments assessing the long-term effect of mCLAS in neurodegeneration may majorly impact the establishment of sleep-based therapies.

Neural Correlates of Cognitive Dysfunction in Conditional Reasoning in Schizophrenia: An Event-related Potential Study.

Schizophrenia patients show impaired conditional reasoning. This study was to investigate event-related potential (ERP) characteristics of the conditional reasoning in schizophrenia. Participants included 24 schizophrenia patients and 30 normal controls (NCs), and the measurements of ERPs were conducted during the Wason selection task. Results showed that NCs consistently outperformed schizophrenia patients in terms of accuracy. Among the different rule types of the task, the precautionary type experiment yielded the highest accuracy rates. In contrast, both the descriptive and abstract type experiments resulted in lower accuracy. The RTs of the abstract type experiment were the shortest among the four experiments. In the abstract type of the Wason selection task, the NCs exhibited higher amplitudes for both the N1 and P2 components compared to the schizophrenia patients. At the parietal lobe, the N2 amplitudes were higher for the social contract type of the task compared to the precautionary version. At the frontal lobe, the N2 amplitudes were highest for the abstract type of the task. In the abstract type, the N2 amplitude at the parietal lobe was higher than that at the central lobe. The NCs displayed lower amplitudes for both the P3 and slow wave compared to the schizophrenia patients. Differences were observed between the NC and schizophrenia groups in terms of the latencies for N1, P2, N2, P3 and slow wave components across different experiment types and regions of interest. In conclusion, the observed ERP patterns provide valuable insights into the neural mechanisms underlying the Wason selection task, highlighting the differences between NCs and patients with schizophrenia.

The Association of Physical Activity and Stress-induced Neurocognitive Impairments in Inhibitory Control in Children

Background Evaluation stress can impair inhibitory control, limiting the ability of children to perform cognitively. However, evidence on protective factors is lacking as stress-induced cognitive impairments are poorly understood. High physical activity has been related to better inhibitory control and has the potential to buffer the response to a stressor. We investigated the association of physical activity and stress-induced changes in inhibitory control as well as its underlying cognitive control processes (i.e., conflict monitoring and resolution). Method Participants (10 to 13 y) with either low (N = 55) or high moderate-to-vigorous physical activity (N = 55) completed the Trier Social Stress Test for Children (TSST-C) and a control task in a randomized order. During both conditions, salivary cortisol was collected. Additionally, a computerized Stroop task was administered before and after the experimental conditions. The N200 and positive slow wave (PSW) components of event-related potentials elicited by the Stroop task were recorded using electroencephalography. Results In comparison to the control task, the TSST-C elicited a pre-to post-test decrease of accuracy on incompatible trials. Path-analyses further revealed that this decrease was related to low physical activity and a reduced PSW amplitude. However, both the N200 and PSW amplitudes did not mediate the relation between physical activity groups and performance on the Stroop task. Conclusion In children, evaluation stress decreases inhibitory control partly due to a reduced effectiveness of conflict resolution processes. Only children with high physical activity maintain inhibitory control after facing the stressor. However, this protective effect cannot be attributed to changes in conflict monitoring and resolution.

Participation of Modulating Rhythms of the Decasecond Range in Intersystem Correlation Interactions in Early Rat Ontogeny.

On newborn non-narcotized 1-day-old (P1) and 16-day-old (P16) rats, a detailed analysis of intersystem somatovisceral interactions (ISI) mediated by decasecond (D1, 5-50 sec) range modulating rhythms was performed. Correlation interactions of the main body systems - cardiovascular, respiratory and somatomotor systems in norm and under conditions of changes in the level of cholinergic regulation were studied. Spectral correlation analysis was used to determine the participation of D1 range modulating rhythms in ISI. It was found that at P1, D1 range rhythms do not play a significant role in integrative processes. In P16 the activation of cholinergic structures, caused by the introduction of the acetylcholinesterase inhibitor physostigmine (eserine) leads to significant disturbances in the degree of correlation in the D1 range. Blockade of muscarinic and nicotinic cholinoreceptors does not alter the degree of correlation of systemic pairs in the slow-wave region (D1-low, 8-50 sec) of the D1 range. Under the influence on the cholinoreactive structures, the most significant changes in the degree of correlation in the ISI affect the somatorespiratory systemic pair. The results obtained indicate that the representation of the slow-wave components of D1 range modulating rhythms involved in the ISI increase during the first weeks of postnatal ontogeny. Changes in the level of cholinergic activation do not directly influence on ISI mediated by D1-low sub-band rhythms.

Recording and analysis of slow waves of the small intestine of mice with heart failure.

Gastrointestinal (GI) symptoms in heart failure (HF) patients are associated with increased morbidity and mortality. We hypothesized that HF reduces bioelectrical activity underlying peristalsis. In this study, we aimed to establish a method to capture and analyze slow waves (SW) in the small intestine in mice with HF. We established a model of HF secondary to coronary artery disease in mice overexpressing tissue-nonspecific alkaline phosphatase (TNAP) in endothelial cells. The myoelectric activity was recorded from the small intestine in live animals under anesthesia. The low- and high-frequency components of SW were isolated in MATLAB and compared between the control (n=12) and eTNAP groups (n=8). C-kit-positive interstitial cells of Cajal (ICC) and Pgp9.5-positive myenteric neurons were detected by immunofluorescence. Myenteric ganglia were assessed by hematoxylin and eosin (H&E) staining. SW activity was successfully captured in vivo, with both high- and low-frequency components. Low-frequency component of SW was not different between endothelial TNAP (eTNAP) and control mice (mean[95% CI]: 0.032[0.025-0.039] vs. 0.040[0.028-0.052]). High-frequency component of SW showed a reduction eTNAP mice relative to controls (0.221[0.140-0.302] vs. 0.394[0.295-0.489], p < 0.01). Dysrhythmia was also apparent upon visual review of signals. The density of ICC and neuronal networks remained the same between the two groups. No significant reduction in the size of myenteric ganglia of eTNAP mice was observed. A method to acquire SW activity from small intestines in vivo and isolate low- and high-frequency components was established. The results indicate that HF might be associated with reduced high-frequency SW activity.

The role of N-cholinoreceptors in somatovisceral intersystemic interactions in early rat ontogenesis

Interaction of slow-wave rhythmic components of cardiac, respiratory and motor activities was analyzed in non-narcotized of newborn 1-day-old (P1) and 16-day-old (P16) Wistar rat pups under normal and impaired cholinergic regulation. Functional activity of these three systems is rhythmic, and coordination of their functioning is an important element of the mechanism of adaptive rearrangements under changing factors of the external and internal environment. The acetylcholinesterase inhibitor physostigmine (eserine) was used to increase the level of endogenous acetylcholine and enhance cholinergic effects. To reveal the role of N-cholinoreceptors in intersystemic somatovisceral interactions (ISI), we performed blockade of this receptor type with benzohexonium. Administration of physostigmine leads to the development of a number of pathological reactions and a decrease in the level of ISI in all ranges of modulating rhythms in rats of both ages. ISI in younger rats appear to be more resistant to changes in the level of cholinergic activation. Blockade of N-cholinoreceptors causes inhibition of ISI at P1 and partially to their potentialization at P16. The activation of cholinoreactive structures, which occurred against the background of cholinoreceptors blockade, reduces the pathological effects of physostigmine in animals of both ages, but at the same time leads to an attenuation of ISI. This weakening is more pronounced in 16-day old rats, which may indicate the formation of the definitive level of cholinergic regulation in the first weeks of postnatal ontogenesis.

Perceptual Grouping Reveals Distinct Roles for Sustained Slow Wave Activity and Alpha Oscillations in Working Memory.

Multiple neural signals have been found to track the number of items stored in working memory (WM). These signals include oscillatory activity in the alpha band and slow-wave components in human EEG, both of which vary with storage loads and predict individual differences in WM capacity. However, recent evidence suggests that these two signals play distinct roles in spatial attention and item-based storage in WM. Here, we examine the hypothesis that sustained negative voltage deflections over parieto-occipital electrodes reflect the number of individuated items in WM, whereas oscillatory activity in the alpha frequency band (8-12 Hz) within the same electrodes tracks the attended positions in the visual display. We measured EEG activity while participants stored the orientation of visual elements that were either grouped by collinearity or not. This grouping manipulation altered the number of individuated items perceived while holding constant the number of locations occupied by visual stimuli. The negative slow wave tracked the number of items stored and was reduced in amplitude in the grouped condition. By contrast, oscillatory activity in the alpha frequency band tracked the number of positions occupied by the memoranda and was unaffected by perceptual grouping. Perceptual grouping, then, reduced the number of individuated representations stored in WM as reflected by the negative slow wave, whereas the location of each element was actively maintained as indicated by alpha power. These findings contribute to the emerging idea that distinct classes of EEG signals work in concert to successfully maintain on-line representations in WM.

Age-related morphological differences in the spike-and-wave complexes of absence epilepsy

ObjectiveAbsence epilepsy shows age-related clinical features, as is observed in childhood and juvenile absence epilepsy. Electroencephalogram (EEG) is characterized by bursts of 3 Hz spike-and-wave complex (SWC). We noticed a morphological variation of the slow-wave component of SWCs between patients. This study investigated whether the waveform of SWC might be associated with the child’s age of this epilepsy. MethodsDigitally-recorded EEGs under medication-free conditions were collected from 25 children who received the diagnosis of childhood or juvenile absence epilepsy. The morphology of slow wave in SWC in the frontal midline region was quantitatively compared between younger and older children using a cluster-based permutation test. ResultsAt <7 years of age (2.9–6.5 years of age, n = 6), the electrical potential of the descending slope in the slow wave was positively correlated with age whereas this correlation was not observed in patients of ≥7 years of age (7.1–12.9 years, n = 19). A cluster-based permutation test confirmed the results—among the entire slow wave period (0–285 msec), the period of the descending slope (195–260 msec) showed significantly lower potential in patients of <7 years of age in comparison to patients of ≥7 years of age (sum of t-values: 46.57, p-value: 0.011). ConclusionsThe current study demonstrated an age-dependent morphological difference in the slow-wave components of SWCs in EEGs of patients with pediatric absence epilepsy. This finding may provide a clue to understanding the age-related clinical manifestations of this epilepsy.

Pupil Dilation and the Slow Wave ERP Reflect Surprise about Choice Outcome Resulting from Intrinsic Variability in Decision Confidence.

Central to human and animal cognition is the ability to learn from feedback in order to optimize future rewards. Such a learning signal might be encoded and broadcasted by the brain’s arousal systems, including the noradrenergic locus coeruleus. Pupil responses and the positive slow wave component of event-related potentials reflect rapid changes in the arousal level of the brain. Here, we ask whether and how these variables may reflect surprise: the mismatch between one’s expectation about being correct and the outcome of a decision, when expectations fluctuate due to internal factors (e.g., engagement). We show that during an elementary decision task in the face of uncertainty both physiological markers of phasic arousal reflect surprise. We further show that pupil responses and slow wave event-related potential are unrelated to each other and that prediction error computations depend on feedback awareness. These results further advance our understanding of the role of central arousal systems in decision-making under uncertainty.

Sleep Disruption in Epilepsy: Ictal and Interictal Epileptic Activity Matter.

Disturbed sleep is common in epilepsy. The direct influence of nocturnal epileptic activity on sleep fragmentation remains poorly understood. Stereo-electroencephalography paired with polysomnography is the ideal tool to study this relationship. We investigated whether sleep-related epileptic activity is associated with sleep disruption. We visually marked sleep stages, arousals, seizures, and epileptic bursts in 36 patients with focal drug-resistant epilepsy who underwent combined stereo-electroencephalography/polysomnography during presurgical evaluation. Epileptic spikes were detected automatically. Spike and burst indices (n/sec/channel) were computed across four 3-second time windows (baseline sleep, pre-arousal, arousal, and post-arousal). Sleep stage and anatomic localization were tested as modulating factors. We assessed the intra-arousal dynamics of spikes and their relationship with the slow wave component of non-rapid eye-movement sleep (NR) arousals. The vast majority of sleep-related seizures (82.4%; 76.5% asymptomatic) were followed by awakenings or arousals. The epileptic burst index increased significantly before arousals as compared to baseline and postarousal, irrespective of sleep stage or brain area. A similar pre-arousal increase was observed for the spike index in NR stage 2 and rapid eye-movement sleep. In addition, the spike index increased during the arousal itself in neocortical channels, and was strongly correlated with the slow wave component of NR arousals (r = 0.99, p < 0.0001). Sleep fragmentation in focal drug-resistant epilepsy is associated with ictal and interictal epileptic activity. The increase in interictal epileptic activity before arousals suggests its participation in sleep disruption. An additional increase in the spike rate during arousals may result from a sleep-wake boundary instability, suggesting a bidirectional relationship. ANN NEUROL 2020;88:907-920.

Effect of M-Cholinoreceptor Blockade on Somatovisceral Intersystemic Interactions in Newborn Rats after Activation of Cholinoreactive Structures

Interaction of slow-wave rhythmic components of cardiac, respiratory and motor activities was analyzed in non-narcotized neonatal (P1) and early postnatal (P16) rat pups under normal conditions and after activation of cholinoreactive structures. A reversible acetylcholinesterase (AChE) inhibitor physostigmine (eserine) and the M-cholinolytic methacin were used in the experiments. It was established that in intact P1 rats intersystemic interactions are mainly realized via oscillations within the near- and multi-minute ranges. Correlative interactions between the rhythms in the decasecond range that were not involved in integrative processes in P1 rats increased significantly at P16. In rat pups of both ages, changes in the intensity and pattern of motor activity (MA) tended to precede the generation of modulatory oscillations of the respiratory and heart rates. AChE inhibition by physostigmine and subsequent activation of cholinoreactive structures evoked a decrease in the level of intersystemic interactions across all ranges of the modulatory rhythms in rats of both ages. The methacin-evoked blockade of peripheral M-cholinoreceptors (M-ChRs) decreased the level of interactions mediated by the near- and multi-minute rhythms at P1 but augmented them at P16. Physostigmine injection at P1 and P16 exerted no significant effect on cardio-somatomotor interactions, with these interactions in P1 rats being maintained by a wider range of the modulatory rhythms. The same situation was also observed during the physostigmine aftereffect period in all interacting systemic pairs. By contrast, after the blockade of peripheral M-ChRs the existing intersystemic interactions were more difficult to be disrupted in P16 rat pups. The activation of cholinoreactive structures, which occurred against the background of M-ChRs blockade, led to disrupt the coordinating interactions in the “MA–respiratory rate” pair. In P1 rats, these functional relationships did not recover, while in P16 rats they were resumed already during the aftereffect period. The power of modulatory rhythms of activity in the systems studied here was not directly related to intersystemic interactions. Changes in intersystemic interactions were due to heterochrony both in the maturation of these functional systems and the involvement of different cholinoreactive structures in the processes of intersystemic regulation.

Spike-wave discharges in absence epilepsy: segregation of electrographic components reveals distinct pathways of seizure activity.

The major electrophysiological hallmarks of absence seizures are spike and wave discharges (SWDs), consisting of a sharp spike component and a slow wave component. In a widely accepted scheme, these components are functionally coupled and reflect an iterative progression of neuronal excitation during the spike and post-excitatory silence during the wave. In a genetic rat model of absence epilepsy, local pharmacological inhibition of the centromedian thalamus (CM) selectively suppressed the spike component, leaving self-contained waves in epidural recordings. Thalamic inputs induced activity in cortical microcircuits underlying the spike component, while intracortical oscillations generated the wave component. Based on these findings, we propose a model in which oscillatory waves provide adequate time windows for integration of thalamocortical inputs and feedback responses during generation of a synchronized SWD. Spike and wave discharges (SWDs) are the electrographic hallmark of absence seizures and the major diagnostic criterion for childhood absence epilepsy (CAE). In a widely accepted scheme, the alternating sequence of spikes and waves reflects an iterative progression of neuronal excitation during the spike component and post-excitatory silence during the wave component. Here we challenge this view by showing that these two components are not necessarily coupled. In a genetic rat model of CAE, self-contained waves occurred in motor cortex in synchrony with SWDs in the somatosensory system during blockade of afferent input from the thalamus. Current-source density analyses of multi-site local field potentials (LFPs) revealed layer-specific activity, in which thalamic inputs induced a sequence of cellular-synaptic events underlying the spike component, while intracortical oscillations generated the wave component. These findings indicate novel principles of SWDs, where oscillatory cortical waves provide adequate time windows for integration of thalamocortical inputs and feedback responses during generation of seizure activity.

Auditory stimulus- and response-locked ERP components and behavior.

To clarify the functional significance of Go event-related potential (ERP) components, this study aimed to explore stimulus- and response-locked ERP averaging effects on the series of ERP components elicited during an auditory Go/NoGo task. Go stimulus- and response-locked ERP data from 126 healthy young adults (Mage =20.3, SD=2.8years, 83 female) were decomposed using temporal principal components analysis (PCA). The extracted components were then identified as stimulus-specific, response-specific, or common to both stimulus- and response-locked data. MANOVAs were then used to test for stimulus- versus response-locked averaging effects on common component amplitudes to determine their primary functional significance (i.e., stimulus- or response-related). Go stimulus- and response-related component amplitudes were then entered into stepwise linear regressions predicting the reaction time (RT), RT variability, and omission errors. Nine ERP components were extracted from the stimulus- and response-locked data, including N1-1, processing negativity (PN), P2, response-related N2 (RN2), motor potential (MP), P3b, P420, and two slow wave components; SW1 and SW2. N1-1, PN, and P2 were stimulus-specific, whereas, RN2, MP, and P420 were response-specific; P3b, SW1, and SW2 were common to both data sets. P3b, SW1, and SW2 were significantly larger in the response-locked data, indicating that they were primarily response-related. RT, RT variability, and omission errors were predicted by various stimulus- and response-related components, providing further insight into ERP markers of auditory information processing and cognitive control. Further, the results of this study indicate the utility of quantifying some common components (i.e., Go P3b, SW1, and SW2) using the response-locked ERP.

NREM Sleep Instability in Pediatric Migraine Without Aura.

Children with migraine headaches appear to have a range of sleep disturbances. The aim of the present study was to assess the NREM sleep instability in a population of school-aged individuals affected by migraine without aura (MoA). Thirty-three children with MoA (20 males, 13 females, mean age 10.45 ± 2.06 years) underwent to overnight Polysomnographic (PSG) recordings and Cyclic Alternating Pattern (CAP) analyses accordingly with international criteria. MoA group showed a reduction in sleep duration parameters (TIB, SPT, TST; p ≤ 0.001 for all) and in arousal index during REM sleep and an increase in awakenings per hour (AWK/h) vs. Controls (C) (p = 0.008). In particular, MoA children showed a reduced CAP rate% (p ≤ 0.001), CAP rate% in S1 (p ≤ 0.001) and CAP rate% in SWS (p = 0.004) vs. C. Moreover, A phases distribution were characterized by a reduction in slow wave components (total number CAP A1%, CAP A1 index) (p ≤ 0.001) and an increase of fast components representation (total number of CAP A2% and CAP A3%) (p < 0.001) in MoA vs. C. Moreover, MoA children showed an increased A1 and A2 mean duration (p ≤ 0.001). Our findings show a reduction of arousability in MoA group and lower NREM lower sleep instability associated with MoA in children.

Assessment of cracks in pre-stressed concrete railway sleepers by ultrasonic testing

Pre-stressed concrete sleepers are a responsible component of railways infrastructure, which replacement after years of service is costly and labour consuming. Intense dynamic loading and changing weather conditions cause the appearance of cracks leading to sleepers’ degradation and weakening. The necessity of monitoring of sleepers’ condition for the development of cracks is an actual challenge. Currently used visual inspection of the sleepers’ surface doesn’t provide information about the cracks expansion in depth and its progress in time. Ultrasonic testing has been proposed for quantification of transversal and longitudinal cracks using time and energy parameters of ultrasonic signals and evaluating fast and slow components of ultrasound propagation. The method was approved in the field study on the Latvian railway by comparative testing of healthy sleepers and sleepers with cracks. The cracks were gradually divided into groups according to their sizes that was evaluated by visual inspection. It was shown that the gradual enlargement of cracks manifests both in damping of propagated ultrasonic signals and changing the ratio of slow and fast wave components towards the prevalence of slow ones. Combined use of both manifestations provides quantitative indicators of the cracking process.

Reward association alters brain responses to emotional stimuli: ERP evidence.

We investigated the effects of reward learning on the processing of emotional faces using event-related potentials (ERPs). A simple choice game was used to imbue angry and happy faces with a high or low probability of reward. ERPs were recorded in a subsequent test phase in which participants performed a visual search task to discriminate the emotion of a face singleton as being angry or happy without any reward. Results revealed a significant interaction between reward-history and emotion for the N1 and P2 components, in which the difference between the mean amplitudes for angry and happy faces was smaller in the high-reward association condition than in the low-reward association condition. This reward-modulation effect indicates that reward association reduced the initial visual awareness and hence attentional allocation to angry faces. Moreover, we found a positive relationship between the personal trait of reward sensitivity and the reward-modulation effect for the late-latency response-selection related slow positive wave (SPW) component and the behavioral response accuracy, suggesting that participants with higher reward sensitivity may employ more cognitive resources to evaluate the reward history during the late decision stage of emotional processing. Our study contributes to a better understanding of how reward-association history affects both the perceptual and executive levels of emotional face processing.

Stimulus-specific adaptation in the anesthetized mouse revealed by brainstem auditory evoked potentials

Neural responses to sensory inputs in a complex and natural environment must be weighted according to their relevance. To do so, the brain needs to be able to deal with sudden stimulus fluctuations in an ever-changing acoustic environment. Stimulus-specific adaptation (SSA) is a phenomenon of some neurons along the auditory pathway that show a reduced response to repetitive sounds while responsive to those that occur rarely. SSA has been shown from the inferior colliculus to auditory cortex, but has not been detected in the cochlear nucleus. To discover where SSA is first generated along the auditory pathway, auditory brainstem responses (ABRs) to pure tones were evaluated in anesthetized mice using an oddball paradigm. Using a typical narrow band-pass filter, changes in the ABRs suggest unspecific short-term adaptation may occur as early as the auditory nerve fibers. Furthermore, after applying a wide band-pass filter –allowing the visualization of a late slow wave in the ABR– we found a reduction of the amplitude of the response to repetitive sounds, compared to rare ones, in the slow wave component P0 that follow the fast wave V. Previous studies have shown the P0 shows temporal correlation with the sustained responses of inferior colliculus, thus we suggest that this nucleus is the first to show stimulus specific adaptation in the auditory pathway.

Quantitative electrophysiological pattern of neurodegeneration in encephalopathies of various origin

Electrophysiological characteristics of patients with encephalopathy of different etiology are presented. Pathogenic mechanisms affecting the electroencephalographic pattern and quantitative components of electroencephalogram are discussed. The aim of the study was to determine a universal quantitative electrophysiological criterion for the evaluation of neurodegenerative changes in the brain of patients with encephalopathy. We analyzed the data of anamnesis, neurological examination, laboratory tests and electroencephalograms from 389 patients with encephalopathy of post-traumatic, infectious, vascular and mixed etiology. Spectral analysis of electroencephalograms was performed and the values of relative quantitative electrophysiological criterion - the ratio of spectral power in the alpha/theta ranges at rest and during the test with hyperventilation were counted. The ratio of spectral power in the alpha/theta ranges was the lowest in patients of older age group and low - in patients with encephalopathy of infectious etiology. The ratio of the spectral power in the alpha-theta ranges in patients with post-traumatic encephalopathy was significantly different depending on the severity of the traumatic brain injury - mild or moderate/severe. We studied the possibilities of practical application of selected electrophysiological criterion - the ratio of spectral power of rhythms in the alpha-theta ranges. We counted this criterion in 150 patients with encephalopathy for the effectiveness evaluation of the neuroprotective therapy with сortexin. The chosen electrophysiological criterion had proved its effectiveness in therapy monitoring in patients with encephalopathy. In this article we demonstrated the advantages of additional neuroprotective therapy with сortexin. Increase in spectral power of alpha rhythm and decrease in spectral power of slow-wave components in the electroencephalographic pattern characterizes successful neuroprotective therapy with neuropeptides, such as сortexin.

Forward and Reverse Waves: Modeling Distortion Products in the Intracochlear Fluid Pressure

Distortion product otoacoustic emissions are sounds that are emitted by the cochlea due to the nonlinearity of the outer hair cells. These emissions play an important role both in clinical settings and research laboratories. However, how distortion products propagate from their generation location to the middle ear remains unclear; whether distortion products propagate as a slow reverse traveling wave, or as a fast compression wave, through the cochlear fluid has been debated. In this article, we evaluate the contributions of the slow reverse wave and fast compression wave to the propagation of intracochlear distortion products using a physiologically based nonlinear model of the gerbil cochlea. This model includes a 3D two-duct model of the intracochlear fluid and a realistic model of outer hair cell biophysics. Simulations of the distortion products in the cochlear fluid pressure in response to a two-tone stimulus are compared with published in vivo experimental results. Whereas experiments have characterized distortion products at a limited number of locations, this model provides a complete description of the fluid pressure at all locations in the cochlear ducts. As in experiments, the spatial variations of the distortion products in the fluid pressure have some similarities with what is observed in response to a pure tone. Analysis of the fluid pressure demonstrates that although a fast wave component is generated, the slow wave component dominates the response. Decomposition of the model simulations into forward and reverse wave components shows that a slow forward propagating wave is generated due to the reflection of the slow reverse wave at the stapes. Wave interference between the reverse and forward components sometimes complicates the analysis of distortion products propagation using measurements at a few locations.