[The experience in surgical treatment of Gilles de la Tourette's syndrome].
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Adult↗
Biomedical subjects
S V Medvedev
Publications and source records attributed to S V Medvedev.
Prosodic clues to syntactic processing--a PET and ERP study.
Syntactic processing of spoken speech often involves prosodic clues processing. In the present PET and ERP study, subjects listened to phrases in which different prosodic segmentation dramatically changed the meaning of the phrase. In the contrast of segmented vs. non-segmented phrases, PET data revealed activation in the right dorsolateral prefrontal cortex and in the right cerebellum. These brain structures, therefore, might be part of the syntactic analysis network involved in prosodic segmentation and pitch processing. ERP results revealed frontal negativity that was sensitive to the position of the segmenting pause, possibly reflecting prosody-based semantic prediction. The present results are discussed in the context of their relation to brain networks of emotions, prosody, and syntax perception.
Adolescent↗
Error detection mechanisms of the brain: background and prospects.
Historical background of error detection (ED) studies is restored here from the first suggestion of such a mechanism published (Rabbit, 1966) and the first related anatomo-physiological correlates observed [Bechtereva, N.P., Gretchin, V.B., 1968. Physiological foundations of mental activity. Int. Rev. Neurobiol., vol. 11. Academic Press, N.Y., pp. 239-246; Bechtereva, N.P., 1971. Neurophysiological Aspects of Human Mental Activity. Meditzina, Moskow. 120 pp., (in Russian); Bechtereva, N.P., 1974. Neurophysiological Aspects of Human Mental Activity, second edition, revied and complete Meditzina, Moskow. 151 pp., (in Russian)]. Data from evoked potentials together with new opportunities offered by the technological revolution of the 1980s-1990s provided a large body of knowledge on the ED. The overwhelming majority of the papers stress the spatial relation of ED to Anterior Cingulate Cortex. ED was revealed in a number of other zones to whose role should be specially discussed. The other point of interest is the late appearance of ED after the brain signs of correction which seems particularly important considering the supposed functional role of ED. Data of direct observations of ECoG dynamics in left and right human ACC on correct and erroneous test performance are presented. Research on ED resulted in the development of new ways in treatment of the obsessive-compulsive syndrome. Further psychophysiological research into the ED phenomena is considered as one of the priorities of fundamental and applied investigations for the elucidation of human brain functions. Opinion that ED plays an extremely important role in mechanisms of cognition and creativity is further argumented. Investigations in the field can contribute a lot to clinical neurophysiology as well.
Brain↗
PET study of brain maintenance of verbal creative activity.
This paper deals with the investigation of the brain organization of verbal creativity. Psychological tasks were designed in accordance with two main strategies used by volunteers in solving creative tasks. Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) when performing two types of creative tasks in two groups of subjects, each type of the task organizing the creativity process in its own way. Valuable brain correlates of creativity were revealed in the left parieto-temporal regions (Brodmann areas 39 and 40).
Adolescent↗
Lateralized automatic auditory processing of phonetic versus musical information: a PET study.
Previous positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies show that during attentive listening, processing of phonetic information is associated with higher activity in the left auditory cortex than in the right auditory cortex while the opposite is true for musical information. The present PET study determined whether automatically activated neural mechanisms for phonetic and musical information are lateralized. To this end, subjects engaged in a visual word classification task were presented with phonetic sound sequences consisting of frequent (P = 0.8) and infrequent (P = 0.2) phonemes and with musical sound sequences consisting of frequent (P = 0.8) and infrequent (P = 0.2) chords. The phonemes and chords were matched in spectral complexity as well as in the magnitude of frequency difference between the frequent and infrequent sounds (/e/ vs. /o/; A major vs. A minor). In addition, control sequences, consisting of either frequent (/e/; A major) or infrequent sounds (/o/; A minor) were employed in separate blocks. When sound sequences consisted of intermixed frequent and infrequent sounds, automatic phonetic processing was lateralized to the left hemisphere and musical to the right hemisphere. This lateralization, however, did not occur in control blocks with one type of sound (frequent or infrequent). The data thus indicate that automatic activation of lateralized neuronal circuits requires sound comparison based on short-term sound representations.
Adult↗
Selective tuning of the left and right auditory cortices during spatially directed attention.
Effects of spatially directed auditory attention on human brain activity, as indicated by changes in regional cerebral blood flow (rCBF), were measured with positron emission tomography (PET). Subjects attended to left-ear tones, right-ear tones, or foveal visual stimuli presented at rapid rates in three concurrent stimulus sequences. It was found that attending selectively to the right-ear input activated the auditory cortex predominantly in the left hemisphere and vice versa. This selective tuning of the left and right auditory cortices according to the direction of attention was presumably controlled by executive attention mechanisms of the frontal cortex, where enhanced activation during auditory attention was also observed.
Acoustic Stimulation↗
[Transcranial magnetic stimulation in neurotic depression].
Transcranial magnetic stimulation (TMS) was applied in combination with psychotherapy in patients with neurotic depression, including 15 patients of the experimental group and 14 patients of the control one. 10 sessions of daily TMS for the patients from the experimental group (0.015 T, 40 pulses per sec) were performed at the same time for 20 min (twice for 10 min with 5-min interval) in a room which excluded any external stimulation. TMS was performed by contact method: 5 cm coil was applied to the left prefrontal area. The control group received the imitation of TMS-procedure stimulation. The improvement of mental state was in 13 patients of experimental group and in 3 of control one. The course of TMS resulted in a significant attenuation of depression by the Hamilton Depression Rating scale (from 22.9 to 8.6) and the Anxiety Inventory (from 39.4 to 26.6), that was significantly higher in comparison with the control. There weren't found any TMS-related changes in blood pressure and pulse rate as well as any pathological EEG symptoms.
Adult↗
Properties of neuronal activity in cortex and subcortical nuclei of the human brain during single-word processing.
Neuronal impulse activity (NIA) in different cortical areas, subcortical nuclei of the thalamus and striopallidum was recorded via depth electrodes in human patients as they performed a visual word recognition task. The properties of neuronal responsiveness were compared across regions. During single-word processing approximately 75-80% of the responsive cortical neurons were characterized by poststimulus inhibition of firing rate; an increased firing rate (i.e., excitatory response) was observed in about 20-25% of the responsive cortical neurons. Among the subcortical nuclei, mainly in the thalamus and striopallidum, more than 90% of the responsive neurons were characterized by poststimulus excitation; less than 10% exhibited poststimulus inhibition of firing rate.
Adolescent↗
Neuronal activity in frontal speech area 44 of the human cerebral cortex during word recognition.
The activity of neurons was recorded from cortical speech area 44 of human patients with diagnostic and/or therapeutical depth electrodes while they were performing word recognition and object naming tasks. Some cells responded selectively to either semantic or phonological aspects of word processing with the same latency, others responded consecutively to both semantic and phonological features. The present finding provides the first demonstration of neuronal mechanisms in frontal language cortex and evidences that both consecutive and parallel processing of these speech signs occur in neuronal activity of this area.
Frontal Lobe↗
[The effect of local electrostimulation of nerve tissue on its blood supply indices in extreme brain states].
The specifics of local blood flow (LBF) was studied in the areas of electrical stimulation. The occurring changes are determined primarily by the functional state of neural tissue in the stimulation area as well as in the whole brain. The cortex develops an insrement of the LBF after stimulation by the 4th-5th day whereas no such tendency was found in the white matter.
Adult↗
[The clinico-immunological characteristics of patients with severe ischemic brain lesions undergoing combined treatment with the use of intracerebral electrostimulation].
The work analyzes preliminary results of a complex method of treatment of severe ischemic alterations of the brain. Certain parameters of the immune system, its phagocytic link in particular, were studied along with clinico-physiological indices of the functional state of the brain. It was shown that efficient surgical revascularization of the ischemic zones reinforced by electrostimulation at the early postoperative period allowed to substantially restore the motor and speech functions even in cases of critical lesions. Higher indices of functional activity of the phagocytic link of the immune system were noted.
Acute Disease↗
Neural correlate of mental error detection in the human brain cortex.
The use of long-term intracerebral electrodes combined with advances in stereotaxic neurosurgery and a complex multimethodological approach to brain research has made possible a study of the neurophysiological mechanisms of higher mental functions in the course of diagnosis and/or treatment of some chronic cerebral diseases. Investigations in which both local oxygen tension and neuronal impulse activity were recorded while the patients were performing psychological tasks have revealed selective responses in some neuronal populations of the thalamus and of the striopallidal complex, which occur only during erroneous task performance. So-called 'error detector' neurons were also found in the perirolandic and parietotemporal regions of the human brain cortex.
Brain Mapping↗
Visual properties of neurons in the thalamus and striopallidar complex of the human brain.
In parkinsonian patients diagnosed and treated with the aid of long-term intracerebral electrodes, neuronal impulse activity (NIA) was recorded in different nuclei of the thalamus and striopallidar complex during visual testing for orientation sensitivity. Neuronal populations responding only to the presented stimuli with specific angular orientations have been revealed. Orientation-selective neurons have been found with significant responses in NIA observed to the same angular orientations of stimuli during 90 degrees head tilts. It is hypothesized that the visual perception constancy can be maintained with the participation of cerebral nuclei containing such neurons on the basis of convergence of motor, somatosensory and visual information.
Action Potentials↗
Neurophysiological correlates of verbal activity in patients with speech disorders of traumatic etiology.
The article deals with the neurophysiological correlates of the pathophysiological mechanisms of brain trauma. Mechanisms of damaged function restoration by means of therapeutic electrostimulations (TES) are also under discussion. Localization of the brain zones involved in the maintenance of speech and their expansion, while TES is shown on the basis of functional testing and registration of different indices of bioelectrical activity.
Adult↗
Cerebral lateralization for language revealed in neuronal responses of the human brain cortex.
Neuronal impulse activity (NIA) of the cortex and subcortical nuclei in the thalamus and striopallidar complex was studied during performance of the word recognition test in patients with long-term intracerebral electrodes implanted for diagnostics and therapy. In NIA of the left hemisphere cortex, endogenous responses were found to prevail in the interval between expositions of two stimuli, whereas NIA of the right cortex exhibited more responses during perception of stimuli. Asymmetry in neuronal responses of subcortical nuclei in the thalamus and striopallidar complex appeared to differ from that observed in the cerebral cortex.
Brain↗
Psychophysiological micromapping of the human brain.
Neuronal impulse activity (NIA) of cortex and subcortical nuclei of the brain was studied in patients diagnosed and treated with the aid of long-term intracerebral electrodes. A special battery of psychophysiological tests was constructed for study of reflexion of different mental functions in NIA, such as various speech functions, short-term and long-term memory, count and arithmetic operations, emotions. Neuronal populations with the significant responses have been revealed during these testings. First results of psychophysiological mapping of the human brain obtained from NIA data have been presented.
Brain↗
[The distribution of orientation-selective neurons in the thalamic nuclei and striopallidal complex of the human brain].
The impulse activity of 177 neuronal populations analyzed in different nuclei of the thalamus and striopallidal complex during visual testing for orientation sensitivity in 9 parkinsonian patients, diagnosed and treated with the long-term intracerebral electrodes. Orientation-selective neurons related to visual perception constancy were revealed in centrum medianum, zona incerta and nucleus reticularis of the thalamus, nucleus caudatus, globus pallidus medialis. The comparative percentage and distribution of neurons with different properties in the thalamus and striopallidal nuclei were studied.
Cell Count↗
[Neuronal activity in the area of the central gyri of the human cerebral cortex during the recognition of semantic and grammatical signs of speech].
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Cerebral Cortex↗