We aimed to determine the value of the paired-pulse inhibition (PPI) in the auditory cortex in patients with Parkinson's disease (PD) and analyze its dependence on clinical characteristics of the patients. The central (Cz) auditory evoked potentials were recorded in 58 patients with PD and 22 age-matched healthy subjects. PPI of the N1/P2 component was significantly (P < .001) reduced for interstimulus intervals 500, 700, and 900 ms in patients with PD compared to control subjects. The value of PPI correlated negatively with the age of the PD patients (P < .05), age of disease onset (P < .05), body bradykinesia score (P < .01), and positively with the Mini Mental State Examination (MMSE) cognitive score (P < .01). Negative correlation between value of PPI and the age of the healthy subjects (P < .05) was also observed. Thus, results show that cortical inhibitory processes are deficient in PD patients and that the brain's ability to carry out the postexcitatory inhibition is age-dependent.

No abstract

No abstract

No abstract

No abstract

No abstract

The question of the relationship between contingent negative variation and the mechanisms controlling motor and mental functions has received inadequate study. The aims of the present work were to investigate the relationship between the early and late phases of contingent negative variation and the state of motor and mental functions in patients with Parkinson's disease and to study the effects of levodopa on contingent negative variation. Patients with Parkinson's disease showed significant decreases in the amplitudes and areas of both phases of contingent negative variation as compared with subjects of similar age. Correlation analysis demonstrated a negative relationship between the extent of impairment of coordinatory muscle interactions and the amplitudes of both phases of this variation (p < 0.01). There was a positive relationship between the magnitudes of both phases and the state of mental functions, particularly memory (p < 0.05). Treatment of patients with Parkinson's disease with levodopa was followed by a significant increase in the late phase (p < 0.05). The results obtained here provide evidence for the important role of structures supporting both direct motor control and mental functions in forming both phases of contingent negative variation. The greater effect of levodopa on the late phase of contingent negative variation suggests that the efferent system of the basal ganglia has a greater role in generating the late phase than in organizing the early phase of the variation.

The parameters of an event-related EEG potential (ERP), Р300 wave, are now extensively used as objective neurophysiological indices of the state of cognitive functions. At the same time, information on the effects of the autonomic nervous system on the parameters of Р300 is limited. In Parkinson's disease clinics, in addition to the leading motor disorders, more or less clear psychoemotional, cognitive, and autonomic (in particular cardiovascular) impairments are usually observed. This allows one to study the dependence between the cardiovascular dysfunction and intensity of cognitive disorders in Parkinsonian patients. In our study on this contingent, we analyzed correlations between the parameters of P300 potential, indices of the state of the cognitive sphere (determined using a questionnaire, Mini Mental State Examination, MMSE, and a Luriya's test), and indices of variational pulsometry. Thirty-five Parkinsonian patients (49 to 74 years, severity of disease 1.5 to 3.0 by the international classification) were examined. We found a negative influence of excessive sympathetic tonus in cardiovascular control on the state of cognitive functions. The latency of Р300 potential was longer in patients with greater intensities of sympathetic influences on the cardiovascular system. The coefficients of correlation of the latency of Р300 with the amplitude of mode of R-R intervals (AMo), index of tension in the regulatory systems by Baevskii (IT), and index of autonomic balance by Baevskii (IAB) were 0.52 (P < 0.01), 0.36 (P < 0.05), and 0.37 (P < 0.05), respectively. The above autonomic indices demonstrated significant negative correlations with the volume of short-term memory measured by Luriya's test. The Р300 latency, in turn, showed negative correlations with the memory volume estimated by the MMSE scale and Luriya's test. With increase in the age of patients, the degree of the above-mentioned correlations between the Р300 latency, memory volume (by Luriya's test), and parameters of variational pulsometry increased. Our data emphasize the expedience of "routine" studies of the balance of sympathetic and parasympathetic control in pathological states accompanied by clear or subclinical cognitive disorders. Early recognition of cardiovascular dysfunction and its corresponding therapeutic correction should improve the state of brain functions and quality of life in patients suffering from neurodegenerative diseases, in particular from Parkinson's disease.