Transcranial Current Stimulation as a Tool of Neuromodulation of Cognitive Functions in Parkinson’s Disease

Decrease in cognitive function is one of the most common causes of poor life quality and early disability in patients with Parkinson’s disease (PD). Existing methods of treatment are aimed at both correction of motor and non-motor symptoms. Methods of adjuvant therapy (or complementary therapy) for maintaining cognitive functions in patients with PD are of interest. A promising subject of research in this regard is the method of transcranial electric current stimulation (tES). Here we reviewed the current understanding of the pathogenesis of cognitive impairment in PD and of the effects of transcranial direct current stimulation and transcranial alternating current stimulation on the cognitive function of patients with PD-MCI (Parkinson’s Disease–Mild Cognitive Impairment).

Task-positive and task-negative networks in major depressive disorder: A combined fMRI and EEG study

BACKGROUND

The study of intrinsic connectivity networks, i.e., sets of brain regions that show a high degree of interconnectedness even in the absence of a task, showed that major depressive disorder (MDD) patients demonstrate an increased connectivity within the default mode network (DMN), which is active in a resting state and is implicated in self-referential processing, and a decreased connectivity in task-positive networks (TPNs), which increase their activity in attention tasks. Cortical localization of this 'dominance' of the DMN over the TPN in MDD patients is not fully understood. Besides, this effect has been investigated using fMRI and its electrophysiological underpinning is not known.

METHOD

In this study, we tested the dominance hypothesis using seed-based connectivity analysis of resting-state fMRI and EEG data obtained in 41 MDD patients and 23 controls.

RESULTS

In MDD patients, as compared to controls, insula, pallidum/putamen, amygdala, and left dorso- and ventrolateral prefrontal cortex are more strongly connected with DMN than with TPN seeds. In EEG, all significant effects were obtained in the delta frequency band.

LIMITATIONS

fMRI and EEG data were not obtained simultaneously during the same session.

CONCLUSIONS

In MDD patients, major emotion and attention regulation circuits are more strongly connected with DMN than with TPN implying they are more prepared to respond to internally generated self-related thoughts than to environmental challenges.

[The regulation of negative and positive emotions during picture viewing: an ERP study]

The study examines the effects of cognitive reappraisal on the event-related potentials (ERPs) to affective stimuli. Participants (n = 53) were asked either to attend affective images, or to down-regulate negative affect, or to up-regulate positive affect. Reappraisal of negative images was associated with attenuation of the P300 and late positive potential (LPP) over parietal regions, whereas reappraisal of positive images had no significant effect on ERP components. The weak P300 reduction correlated with high personality scores of negative affectivity. We assume that only down-regulation of negative emotions is associated with the changes in primary appraisals, and so far reflected in ERP modulation.

Hypoactivation of reward motivational system in patients with newly diagnosed hypertension grade I-II

In patients with newly diagnosed untreated grade I-II hypertension, EEG oscillations were recorded under conditions activation of the two basic motivational systems, defensive motivational system and positive reinforcement system, evoked by recall of personally meaningful emotional events. The 64-channel EEG and cardiovascular reactivity (beat-by-beat technology) were simultaneously recorded. At rest, hypertensive patients had significantly reduced platelet serotonin concentrations in comparison with healthy individuals. The patients experiencing emotional activation were characterized by significantly lower intensity of positive emotions associated with more pronounced suppression of EEG activity in the delta (2-4 Hz) and theta (ranges of frequency 4-6 and 6-8 Hz) oscillators in the parieto-occipital cortex (zones P and PO) in both hemispheres of the brain. The findings attest to insufficient function of the brain serotonin system and hypoactivation of the reward/reinforcement system in patients with primary hypertension.

[Coupling of brain oscillatory systems with cognitive (experience and valence) and physiological (cardiovascular reactivity) components of emotion]

We investigated the coupling of EEG oscillators with cognitive (experience and valence) and physiological (cardiovascular reactivity) components of emotion. Emotions of anger and joy were evoked in healthy males (n = 49) using a guided imagery method, multichannel EEG and cardiovascular reactivity (Finometer) were simultaneously recorded. Correlational analysis revealed that specially distributed EEG oscillators seem to be selectively involved into cognitive (experience and valence) and physiological (cardiovascular reactivity) components of emotional responding. We showed that low theta (4-6 Hz) activity from medial and lateral frontal cortex of the right hemisphere predominantly correlated with the anger experience, high alpha (10-12 and 12-14 Hz) and gamma (30-45 Hz) activity from central-parieto-occipital regions of the left hemisphere--with cardiovascular reactivity to anger and joy, gamma-activity (30-45 Hz) from the left hemisphere in parietal areas--with cardiovascular reactivity to joy. The findings suggest that specially distributed neuronal networks oscillating at different frequencies may be regarded as a putative neurobiological mechanism coordination dynamical balance between cognitive and physiological components of emotion as well as psycho-neuro-somatic relationships within the mind-brain-body system.

[Features of brain oscillatory activity and cardiac defense in treatment arterial hypertensives]

Stress reactivity of the motivational system of defense can be assessed with the aid the cardiac defense response (CDR) - the reaction of the cardiovascular system to unexpected aversive unconditioned stimulus. The main objective of the study was revealing putative contribution of oscillatory systems of the brain into central pathogenic mechanisms of enhanced blood pressure (BP) stress-reactivity in naive patients with arterial hypertension (AH) of the 1st-2nd degrees (n = 17) and healthy control (n = 19) subjects. Using dynamic registration "beat-by-beat" arterial pressure, and oscillatory activity related EEG (64 channels) is estimated using the event-related synchronization/desynchronization (ERD/ERS). Along with abnormally high blood pressure in patients with hypertension background set significantly lower concentrations of serotonin blood platelets and increased tonic activation of the left hemisphere, reflected in the asymmetric reduction of delta- (2-4 Hz) and theta-1 (4-6 Hz) power in the central and parietal cortex in the hemisphere CDR of the patients are characterized by hyperactivity both short- and long-latency components of blood pressure. According to the dynamic analysis of the concomitant EEG, long-latency BP components may be accounted by, among other mechanisms, weakening of the descending ("top-down") inhibitory control, hypothetically implemented with the high-frequency EEG alpha (10-12 Hz) oscillations from the medial central-parietal cortex of both hemispheres of the brain.

[Brain oscillations and individual variability of cardiac defense in human]

Cardiac defense response (CDR) is a specific dynamic pattern of the short- and long-latency cardiovascular reactivity (usually based on HR and/or arterial BP variables) in response an intense aversive unexpected stimulus. The CDR reflects activity of the defensive motivational system along with behavioral coping programs. The aim of the study was to estimate the putative contribution of brain oscillations into the central mechanisms of the CDR individual variability. EEG and cardiovascular concomitants of the CDR were estimated using the event-related synchroniza- tion/desynchronization (ERD/ERS) in different frequency bands as well as Finapres dependent variables obtained on the "beat-by-beat" basis. The first-ever findings evidenced significant cor- relations of the theta-2 (6-8 Hz) ERD/ERS with the sort-latency, whereas alpha-2 (10-12 Hz) ERD/ERS with the long-latency CDR variability. The hyperreactive long-latency systolic blood pressure CDR component was accompanied by the phase of deficient alpha-2 synchronization. It is suggested that upper theta oscillations are involved into central mechanisms scaling magnitude, whereas high frequency alpha oscillations may be responsible for the top-down inhibitory control of the short-and long-latency ABP stress-reactivity in the CDR.

Evaluation of serum procathepsin B, cystatin B and cystatin C as possible biomarkers of ovarian cancer

Objectives

To evaluate procathepsin B, as well as endogenous inhibitors of cysteine proteases (cystatin B and cystatin C) in biological fluids as possible biomarkers of ovarian cancer. To observe levels of serum procathepsin B in different age groups.

Study design

The sample (N=27) of women with gynaecological tumours included 18 patients with ovarian cancer (n=18) and 9 patients with benign ovarian tumours (n=9); 72 healthy women were in the control group. All patients were treated in Novosibirsk Regional Oncological Center, Russia. Serum samples of healthy women (n=40) aged 18–70 years were used as controls for common biomarker of ovarian cancer CA-125. In the Procathepsin B study, serum samples of healthy women (n=32) aged 18–40 years (n=14), 41–55 years (n=10) and 56–80 (n=8) years were used as controls.

Methods

Common biomarker of ovarian cancer, CA-125, was assayed by using a commercial kit (Vector, Koltsovo, Novosibirsk Region, Russia). Procathepsin B was measured by means of a commercial kit for human procathepsin B (R&D, USA); cystatin C was measured by commercial ELISA kits for human (BioVendor, Czechia); cystatin B was measured by ELISA kits for human (USCN Life Science Inc., Wuhan, China). Statistical analysis was performed by one-way ANOVA (Statistica 10 Program).

Results

In the control group, serum procathepsin B concentration did not reveal age dependency. In the ovarian cancer group, both levels of serum procathepsin B and standard biomarker CA-125 increased significantly (both p<0.001) compared with the control group. In the benign ovarian tumour group, serum procathepsin B (p<0.001) and CA-125 (p=0.004) increased about 2.5- and 8-fold compared to the control group. Serum cystatin B level increased up to 1.7-fold in the ovarian cancer group compared to the control group. The increase of serum CA-125 was about 3.5-fold higher (p=0.017) and procathepsin B was 1.8-fold higher (p<0.05) in the ovarian cancer group compared to the benign tumour group. Cystatin B in ascites fluid increased equally in both ovarian cancer (p<0.001) and benign ovarian tumours group (p<0.05). Cystatin C concentration in ascites fluid increased only in patients with ovarian cancer (p<0.05) and did not change in the benign tumours group. Large increases of procathepsin B level (about 13-fold, p<0.001) and to a lesser degree of cystatin C (1.8-fold, p<0.05) and cystatin B levels (1.4 fold, p<0.001) were revealed in ascites fluids of patients with ovarian cancer compared to the control serum.

The significant difference in serum procathepsin B levels was noted between the ovarian cancer and benign tumour groups (p<0.05), which could be used in differential diagnostics between malignant and benign gynaecological tumours.

Conclusion

Serum procathepsin B demonstrated significant promise as a new biomarker of ovarian cancer.

[Individual preconscious affective biases to threatening and appetitive facial stimulus and cardiovascular stress-reactivity]

AIM

To investigate cardiovascular stress-reactivity in association with individual preconscious affective biases to threatening and appetitive facial stimuli.

PATIENTS AND METHODS

Preconscious affective biases were assessed in healthy individuals (n = 38, mean age 28, 10 years, 1SD = 8.64) using a modified (masked) version of a pictorial emotional Stroop task (backward masking of the angry, fearful and joyful faces).

RESULTS

It was revealed that individual preconscious bias to speeded up perception of angry faces correlates significantly with heightened anxiety, lowered platelet serotonin (5-HT) levels, sustained central overactivation of at rest (as indexed by lowered delta, theta, and beta-1 EEG power over frontal, central and posterior cortical areas) and exaggerated arterial blood pressure stress-reactivity during re-experiencing of personally relevant anger.

CONCLUSIONS

considering uncovered associations, individuals with preconscious bias to speeded up perception of angry faces may be regarded as having enhanced risk to fall sick with essential hypertension, yet this perceptive bias could be seen as a putative neurobehavioral predictor of the risk.

The influence of repeated administration of poloxamer 407 on serum lipoproteins and protease activity in mouse liver and heart

The effects of repeated administration of poloxamer 407 (P-407) on lipoprotein-cholesterol (LP-C) and lipoprotein-triglyceride (LP-TG) fractions and subfractions, as well as the effect on liver and heart proteases, were studied. Repeated administration of P-407 to male CBA mice resulted in a model of atherosclerosis with increased diastolic blood pressure; there was a drastic increase in total serum cholesterol and especially TG. A novel small-angle X-ray scattering method for the determination of the fractional and subfractional composition of LP-C and LP-TG was used. In chronically P-407-treated mice, P-407 significantly increased atherogenic low-density lipoprotein C (LDL-C) fractions, as well as intermediate-density lipoprotein C (IDL-C), and LDL₁₋₃-C subfractions, and very-low-density lipoprotein-C (VLDL-C) fractions, as well as VLDL₁₋₂-C and VLDL₃₋₅-C subfractions), to a lesser extent, the total anti-atherogenic high-density lipoprotein C (HDL-C) fraction, as well as HDL₂-C and HDL₃-C subfractions. Additionally, we demonstrated an increase in the serum chitotriosidase activity, without significant changes in serum matrix metalloprotease (MMP) activity. Morphological changes observed in P-407-treated mice included atherosclerosis in the heart and storage syndrome in the liver macrophages. P-407 significantly increased the activity of cysteine, aspartate proteases, and MMPs in the heart, and only the activity of cathepsin B and MMPs in the liver of mice. Thus, repeated administration of P-407 to mice induced atherosclerosis secondary to sustained dyslipidemia and formation of foamy macrophages in liver, and also modulated the activity of heart and liver proteases.

[Individual variability of cardiovascular reactivity during protective cardiac reflex in humans]

Fail of fast recovering to normal state after aversive event is the key feature of individual intolerance to emotional stress. Within the framework of this idea, dynamics of the arterial blood pressure reactivity was studied studied using defensive reaction of the cardiac defense response elicited by strong aversive acoustic stimuli. Dynamical patterns of cardiovascular responses observed in this reaction makes made it possible to perform affective chronometry of defensive arousal. Healthy male volunteers with normal arterial blood pressure and patients with firstly diagnosed and untreated essential hypertension were studied. The beat-by-beat dynamics of blood pressure values were registered by means of finger-cuff Finapres technology. It was shown that among healthy individuals with normal resting blood pressure values hyperreactive persons with delayed late systolic and diastolic blood pressure increases ocurred. It was suggested that similiarity of delayed pressor effects ofhypereactive healthy individuals and those of hypertension patients incate a high risk of essential hypertension in highly reactive individuals.