Amplitude Of Theta Waves Research Articles

Effects of EEG-Neurofeedback in children with Down syndrome

Background. Down syndrome (DS) is a genetic disorder characterized by varying degrees of mental retardation and neurological complications. Children with DS often experience difficulties with attention, concentration, learning, memory, speech, language, behavior, and physical balance. Methods. This study included 11 children with DS and 10 children with ADHD, aged 6 to 10 years who received treatment at the private clinic “Neyromed Servis” in Tashkent, Uzbekistan. Cognitive functions were analyzed by using Electroencephalography-neurofeedback (EEG-NFB) and the Forbrain headsets. The Wechsler Preschool and Primary Scale of Intelligence and Schulte table were used to assess the effectiveness of non-drug treatment. Results. The utilization of Forbrain headsets enhanced children’s attentiveness as listeners and improved the quality of their voice and speaking. Positive changes in EEG parameters were also registered: theta wave amplitude and theta-tobeta ratio in the frontal lobes decreased significantly. Conclusion. EEG-NFB treatment significantly improved cognitive function, particularly attention, without any side effects in observed children. Moreover, impulsivity as well as hyperactivity decreased gradually. Additionally, after using of the Forbrain method, vocabulary in children improved by 20-40% across all groups.

Local Experience-Dependent Changes in the Wake EEG after Prolonged Wakefulness

Prolonged wakefulness leads to a progressive increase in sleep pressure, reflected in a global increase in slow wave activity (SWA, 0.5-4.5 Hz) in the sleep electroencephalogram (EEG). A global increase in wake theta activity (5-9 Hz) also occurs. Recently, it was shown that prolonged wakefulness in rodents leads to signs of "local sleep" in an otherwise awake brain, accompanied by a slow/theta wave (2-6 Hz) in the local EEG that occurs at different times in different cortical areas. Compelling evidence in animals and humans also indicates that sleep is locally regulated by the amount of experience-dependent plasticity. Here, we asked whether the extended practice of tasks that involve specific brain circuits results in increased occurrence of local intermittent theta waves in the human EEG, above and beyond the global EEG changes previously described. Participants recorded with high-density EEG completed 2 experiments during which they stayed awake ≥ 24 h practicing a language task (audiobook listening [AB]) or a visuomotor task (driving simulator [DS]). Sleep laboratory. 16 healthy participants (7 females). Two extended wake periods. Both conditions resulted in global increases in resting wake EEG theta power at the end of 24 h of wake, accompanied by increased sleepiness. Moreover, wake theta power as well as the occurrence and amplitude of theta waves showed regional, task-dependent changes, increasing more over left frontal derivations in AB, and over posterior parietal regions in DS. These local changes in wake theta power correlated with similar local changes in sleep low frequencies including SWA. Extended experience-dependent plasticity of specific circuits results in a local increase of the wake theta EEG power in those regions, followed by more intense sleep, as reflected by SWA, over the same areas.

Effects of Neurofeedback Training on Attention in Children with Intellectual Disability

This study investigated effects of neurofeedback (NFB) training on attention in children with intellectual disability (ID). Twenty-one children with ID were assigned to an NFB training group (n = 7), to a visual perception (VP) training group (n = 7), or to a no-treatment group (n = 7). Two groups received 36 sessions of NFB or VP training, respectively, over 12 weeks. Children's Color Trails Test–2, Stroop Color and Word Test, and Digit Span were administered to all participants before and after training. The follow-up study was conducted with both the NFB and VP groups in the same way after 3 months. The EEGs of the NFB group also were measured. The NFB group showed significantly improved scores on the all tests compared to the 2 control groups. The brainwaves of the frontal lobes of the NFB group declined significantly in theta wave amplitude and theta-to-beta ratio. The NFB results were maintained in the follow-up study. Beta/SMR uptraining seemed to be an effective way to enhance attention in childre...

Study on the Operator's Mental Activity under Unexpected Control System's Condition

It is difficult for human operator to control complex and large system by hand, because the delay of system response could be long. Although some previous studies characterized the progress in the manual control, the relation between the operator's progress and mental activity was not clear. In this study, we tried to make the relation clear and conducted a simulation experiment to compare the subject's performances and background electroencephalograms (EEGs). The EEGs were measured based on international 10–20 method while the subject controlled a target on the simulator. The subjects were 12 male students ranging from 19 to 23 years old. As the results, we found that the amplitude of theta waves at frontal region was getting higher when the subjects were under the unexpected condition.

Physiology of long pranayamic breathing: Neural respiratory elements may provide a mechanism that explains how slow deep breathing shifts the autonomic nervous system

Pranayamic breathing, defined as a manipulation of breath movement, has been shown to contribute to a physiologic response characterized by the presence of decreased oxygen consumption, decreased heart rate, and decreased blood pressure, as well as increased theta wave amplitude in EEG recordings, increased parasympathetic activity accompanied by the experience of alertness and reinvigoration. The mechanism of how pranayamic breathing interacts with the nervous system affecting metabolism and autonomic functions remains to be clearly understood. It is our hypothesis that voluntary slow deep breathing functionally resets the autonomic nervous system through stretch-induced inhibitory signals and hyperpolarization currents propagated through both neural and non-neural tissue which synchronizes neural elements in the heart, lungs, limbic system and cortex. During inspiration, stretching of lung tissue produces inhibitory signals by action of slowly adapting stretch receptors (SARs) and hyperpolarization current by action of fibroblasts. Both inhibitory impulses and hyperpolarization current are known to synchronize neural elements leading to the modulation of the nervous system and decreased metabolic activity indicative of the parasympathetic state. In this paper we propose pranayama's physiologic mechanism through a cellular and systems level perspective, involving both neural and non-neural elements. This theoretical description describes a common physiological mechanism underlying pranayama and elucidate the role of the respiratory and cardiovascular system on modulating the autonomic nervous system. Along with facilitating the design of clinical breathing techniques for the treatment of autonomic nervous system and other disorders, this model will also validate pranayama as a topic requiring more research.

Theta activity in the waking EEG is a marker of sleep propensity in the rat

In humans, EEG power in the theta frequency band (5–8 Hz) during quiet waking increases during sleep deprivation (SD), and predicts the subsequent homeostatic increase of sleep slow-wave activity (SWA; EEG power between 0.5 and 4.0 Hz). These findings indicate that theta power in waking is an EEG variable, which reflects the rise in sleep propensity. In rodents, a number of short sleep attempts, as well as SWA in the waking EEG increase in the course of SD, but neither variable predicts the subsequent homeostatic increase of EEG SWA during recovery sleep. To investigate whether there is an EEG marker for sleep propensity also in rodents, the EEG of the rat was recorded during 6 h SD in the first half of the light period (SDL, n = 7). During SDL, power of the waking EEG showed an increase in the delta (1.5–4 Hz) and low theta (5–6.5 Hz) band. Based on the neck muscle EMG, wakefulness was subdivided into active (high EMG activity) and quiet (low EMG activity) waking. During quiet waking, the theta peak occurred at 5.5 Hz, the frequency at which the increase of EEG power during SD was most pronounced. This increase was due to higher amplitude of theta waves, while wave incidence (frequency) was unchanged. Correlation analysis showed that the rise in EEG power in the 5–7 Hz band during SD predicted the subsequent enhancement of SWA in non-rapid eye movement sleep. The analysis of data of a further batch of rats which were sleep deprived for 6 h after dark onset (SDD, n = 7) revealed a significant increase in theta-wave amplitude during the SD and a tendency for a similar, positive correlation between the increase of theta power (5–7 Hz) and subsequent SWA. The results indicate that in rats, as in humans, a specific waking EEG frequency, i.e., theta power in quiet waking is a marker of sleep propensity.

Reticular stimulation evokes suppression of CA1 synaptic responses and generation of theta through separate mechanisms.

The induction of hippocampal theta by reticular stimulation involves a relay to the hippocampus via the posterior hypothalamic-supramammillary region and then the medial septum. Interestingly, sensory- or behaviour-induced theta is accompanied by suppression of hippocampal field CA1 synaptic responses. In the present study, performed on anaesthetized rats, we observed that reticular stimulation also induced a suppression of the CA1 pyramidal cell population spike and the corresponding dendritic field excitatory postsynaptic potential evoked by field CA3 stimulation. This suppression was observed at stimulation intensity below the threshold for generation of CA1 theta and was maximal at stimulation intensities at the threshold for theta. The frequency and amplitude of theta waves, by contrast, increased further with increasing reticular stimulation voltage. Neural inactivation by microinjection of the local anaesthetic procaine (20% w/v, 0.1-0.2 microL) or the inhibitory ligand gamma aminobutyric acid (0.8 m, 0.5 micro L) in the posterior hypothalamic regions, especially the ipsilateral medial supramammillary region, or the medial septum attenuated both the suppression of CA1 pyramidal cell synaptic excitability and theta generation. However, the effects of microinjection on suppression and theta were not always in parallel. Furthermore, the effect of microinjection of gamma aminobutyric acid on reticularly elicited suppression was observed from relatively fewer sites in the posterior hypothalamus as compared with that on theta activation. These results suggest that reticular stimulation evokes an inhibition of CA1 pyramidal cell excitability that (i) is mediated, at least in part, via medial supramammillary and septal regions, but (ii) involves a separate neural pathway from theta generation.

The extracellular current blocking effect of cesium chloride on the theta wave in the rabbit hippocampal CA1 region

We studied the extracellular effects of cesium chloride (CsCl), a blocker of the hyperpolarization-activated cationic current ( I h), on the hippocampal theta wave in pentobarbital-anesthetized rabbits. We recorded spontaneous field potentials at the hippocampal CA1 region before and at three time periods after CsCl or saline injections. We found that CsCl injected into the apical dendritic layer attenuated the theta wave amplitude. CsCl affected neither the frequency nor the phase reversal of the theta wave between the apical and basal dendritic layers. Our findings indicate that I h in pyramidal neurons contributes to current generation of the limbic theta wave in vivo.

Regulation of the septal pacemaker theta rhythm by the cervical nuclei of the midbrain.

Neuronal activity in the medial septal region (the medial nucleus and the diagonal band nucleus, MN-DBN) was recorded along with hippocampal EEG traces in conscious rabbits with stimulatory electrodes implanted in the median cervical nucleus (MCN) and the reticular formation (RF) of the midbrain and pons. In all animals with electrodes in the MCN, the background theta activity frequency was low (4.6 +/- 0.15 Hz) as compared with intact rabbits or those with electrodes implanted only in the RF (5.2 +/- 0.19 Hz, p < 0.5). Stimulation of the MCN with weak low-frequency impulses reduced theta volleys from MN-DBN cells, reducing their frequency and regularity and inducing the appearance or strengthening of low-frequency delta modulation. The number of spikes in a volley decreased, and the duration of inter-volley intervals increased. Stimulation of the MCN led to a gradual decrease in the frequency and amplitude of theta waves, induced irregular delta waves and spindles of 12 Hz in the hippocampal EEG. Stimulation of the RF produced the opposite changes in volley activity in the MN-DBN and hippocampal EEG, with increases in theta and decreases in delta components. These results support a role for the midbrain cervical nuclei as structures limiting the generation of theta activity by the reticular-septal system, but do not support the existence of an MN-DBN-independent high-frequency serotoninergic theta rhythm. It is proposed that the effect of the MCN may be important for suppression and switching of attention.

EEG changes during mental calculation, reverse recitation and association exercises in patients with dementia of the Alzheimer type.

The cerebral functional impairment in dementia of the Alzheimer type (DAT) was a quantitatively assessed using easily repeatable electroencephalographic analysis. Waveform recognition was employed to analyze the EEG (electroencephalogram) changes displayed before and after tasks of mental calculation, reverse recitation and mental association. Marked decrements in the incidence of theta and alpha waves together with decrements of the average amplitude of alpha waves were noted in normal elderly subjects after mental calculation and reverse recitation. In the patients with DAT, mental association tasks evoked pronounced decrements in the average amplitude of theta waves, the average frequency of alpha waves, and both the average frequency and average amplitude of beta waves. These results indicate that analysis of EEG activity responses to mental tasks provides an objective assessment of dementia.

Effects of endorphin derivatives on the EEG alterations induced by corticotropin releasing factor in the rabbit hippocampus

Corticotropin releasing factor (CRF), injected into the cerebral ventricles (i.c.v.) of rabbits, induced EEG limbic seizures, behavioural excitability, stereotyped behaviour and the tardive enhancement of hippocampal theta voltage and frequency. The beta-endorphin cleavage derivatives des-tyr-gamma-endorphin (DT gamma E) and des-enkephalin-gamma-endorphin (DE gamma E), when injected i.v. for 4 days prevented the EEG ictal seizures induced by CRF in the hippocampus of rabbits and partly prevented the tardive enhancement of theta wave amplitude and frequency. These results suggest the possibility that these peptides may have antiepileptogenic properties.