Electroencephalographic Theta Research Articles

Timing and cortical region matter: theta power differences between teenagers affected by Major Depression and healthy controls

In adults affected by Major Depressive Disorder (MDD), most findings point to higher electroencephalographic (EEG) theta power during wake compared to healthy controls (HC) as a potential biomarker aiding the diagnostic process or subgrouping for stratified treatment. Besides these group differences, theta power is modulated by time of day, sleep/wake history, and age. Thus, we aimed at assessing if the time of recording alters theta power in teenagers affected by MDD or HC. Standardized wake EEG power was assessed with high-density EEG in 15 children and adolescents with MDD and in 15 age- and sex-matched HC in the evening and morning. Using a two-way ANOVA, group, time, and their interaction were tested. In patients, the current severity of depression was rated using the Children’s Depression Rating Scale. Broadband EEG power was lower in the morning after sleep, with a significant interaction (group x time) in central regions in the 4-6 Hz range. In MDD relative to HC, theta power was decreased over occipital areas in the evening and increased over frontal areas in the morning. A higher frontal theta power was correlated with more severe depressive mood in the morning but not in the evening. This was a cross-sectional study design, including patients on antidepressant medication. In conclusion, depending on time of recording, region-specific opposite differences of theta power were found between teenagers with MDD and HC. These findings stress the importance of the time of the recording when investigating theta power’s relationship to psychopathology.

Neuromodulation of inhibitory control using phase-lagged transcranial alternating current stimulation

BackgroundTranscranial alternating current stimulation (tACS) is a prominent non-invasive brain stimulation method for modulating neural oscillations and enhancing human cognitive function. This study aimed to investigate the effects of individualized theta tACS delivered in-phase and out-of-phase between the dorsal anterior cingulate cortex (dACC) and left dorsolateral prefrontal cortex (lDLPFC) during inhibitory control performance.MethodsThe participants engaged in a Stroop task with phase-lagged theta tACS over individually optimized high-density electrode montages targeting the dACC and lDLPFC. We analyzed task performance, event-related potentials, and prestimulus electroencephalographic theta and alpha power.ResultsWe observed significantly reduced reaction times following out-of-phase tACS, accompanied by reduced frontocentral N1 and N2 amplitudes, enhanced parieto-occipital P1 amplitudes, and pronounced frontocentral late sustained potentials. Out-of-phase stimulation also resulted in significantly higher prestimulus frontocentral theta and alpha activity.ConclusionsThese findings suggest that out-of-phase theta tACS potently modulates top-down inhibitory control, supporting the feasibility of phase-lagged tACS to enhance inhibitory control performance.

Resting-state electroencephalography theta predicts neurofeedback treatment 4-month follow-up response in nicotine addiction

BackgroundThe high rate of long-term relapse is a major cause of smoking cessation failure. Recently, neurofeedback training has been widely used in the treatment of nicotine addiction; however, approximately 30%...

Feasibility, efficacy, and functional relevance of automated auditory closed-loop suppression of slow-wave sleep in humans.

Slow-wave sleep (SWS) is a fundamental physiological process, and its modulation is of interest for basic science and clinical applications. However, automatised protocols for the suppression of SWS are lacking. We describe the development of a novel protocol for the automated detection (based on the whole head topography of frontal slow waves) and suppression of SWS (through closed-loop modulated randomised pulsed noise), and assessed the feasibility, efficacy and functional relevance compared to sham stimulation in 15 healthy young adults in a repeated-measure sleep laboratory study. Auditory compared to sham stimulation resulted in a highly significant reduction of SWS by 30% without affecting total sleep time. The reduction of SWS was associated with an increase in lighter non-rapid eye movement sleep and a shift of slow-wave activity towards the end of the night, indicative of a homeostatic response and functional relevance. Still, cumulative slow-wave activity across the night was significantly reduced by 23%. Undisturbed sleep led to an evening to morning reduction of wake electroencephalographic theta activity, thought to reflect synaptic downscaling during SWS, while suppression of SWS inhibited this dissipation. We provide evidence for the feasibility, efficacy, and functional relevance of a novel fully automated protocol for SWS suppression based on auditory closed-loop stimulation. Future work is needed to further test for functional relevance and potential clinical applications.

Distinct Effects of the Apolipoprotein E ε4 Genotype on Associations Between Delayed Recall Performance and Resting-State Electroencephalography Theta Power in Elderly People Without Dementia.

BackgroundAbnormal electroencephalography (EEG) activity has been demonstrated in mild cognitive impairment (MCI), and theta rhythm might be inversely related to memory. The apolipoprotein E (ApoE) epsilon 4 (ε4) allele, as a genetic vulnerability factor for pathologic and normal age-related cognitive decline, may influence different patterns of cognitive dysfunction. Therefore, the present study primarily aimed to verify the role of resting theta rhythm in delayed recall deficits, and further explore the effects of the ApoE genotype on the associations between the resting theta power and delayed recall performance in the elderly individuals without dementia.MethodsA total of 47 individuals without dementia, including 23 MCI and 24 healthy subjects (HCs), participated in the study. All subjects were administered the Hopkins Verbal Learning Test–Revised (HVLT-R) to measure delayed recall performance. Power spectra based on resting-state EEG data were used to examine brain oscillations. Linear regression was used to examine the relationships between EEG power and delayed recall performance in each subgroup.ResultsThe increased theta power in the bilateral central and temporal areas (Ps = 0.02–0.044, uncorrected) was found in the patients with MCI, and were negatively correlated with delayed recall performance (rs = −0.358 to −0.306, Ps = 0.014–0.036, FDR corrected) in the elderly individuals without dementia. The worse delayed recall performance was associated with higher theta power in the left central and temporal areas, especially in ApoE ε4 non-carriers and not in carriers (rs = −0.404 to −0.369, Ps = 0.02–0.035, uncorrected).ConclusionOur study suggests that theta disturbances might contribute to delayed recall memory decline. The ApoE genotype may have distinct effects on EEG-based neural correlates of episodic memory performance.

Features of quantitative EEG in children with hyperkinetic disorder

At the basis of numerous mental disorders lies a synaptic transmission impairment that causes metabolic and ionic changes and affects the current functional state of the brain, the reflection of which we find in electroencephalographic examination.Objective of the study: identification of electroencephalographic features in children under conditions of biochemical heterogeneity of hyperkinetic disorder (HD).Material and methods. 404 children aged 6-8 years with HD were divided into three subgroups according to the state of monoamine activity: the 1-st subgroup with a combination of hypofunction of the dopaminergic and hyperfunction of the noradrenergic systems — 120 children, the 2-nd subgroup with a combination of hyperfunction of the noradrenergic system with relative balance dopamine — 136 children, and the 3-d with a combination of hyperfunction of the dopamine and hypofunction of the noradrenergic systems — 148 children. In the selected groups, the serotonin system plays an inhibitory and modulating role in relation to the catecholamine metabolism systems. The control group consisted of 90 children (54 boys and 36 girls). An electroencephalographic study was carried out, where the following ranges and subranges were differentiated: theta rhythm (4–8 Hz) and beta1 rhythm (14–20 Hz). The power ratios of theta — and — beta1 rhythms (theta/beta1) were calculated.Results. It was the serotonin system that turned out to be the determining factor in the neurophysiological characteristics of HD. Moreover, the division into subgroups, based on the biochemical characteristics of children with HD, did not allow us to obtain significant differences. The only feature that globally distinguishes the subgroups from each other was the increase in the theta/beta1 activity index, corresponding to an increase in the tension and activity of the serotonin system from subgroup 1 to 3. The data obtained allow us to assert that the electroencephalographic index theta / beta1 can serve as a marker of inattention in children with hyperkinetic disorder and reflects the established state of imbalance of all monoamine systems, but better characterizes the behavior of the tryptophan system.Conclusion. The data on the relationship between the power of theta/beta1 rhythms in the EEG may indicate the nature of the activity of the serotonin system in prospective studies, providing a personalized approach to the selection of drug therapy in children with HD.

Power spectral densities of electroencephalographic theta and alpha frequency waves during information processing of language comprehension

A cross sectional study was conducted to assess electroencephalograph (EEG) Power Spectral Densities (PSD) of alpha and theta frequency bands for an integrative functional role of working memory (WM) in the architectonics of a synthesized and coordinated communication system as exemplified by the observable phenomenon of the evolved structured Language of Human Mind by using Visuo-Spatial Delayed Match to Sample (DMTS) task. The analysis exhibited significant Event Related Synchronization (ERS) along theta wave-form at temporal region along with Lateral Asymmetry Index (LAI) of Alpha Event Related Desynchronization (ERD) at parietal region suggestive of the phenomenal singularity of ERS of theta along temporal regions that seems to be intricately interwoven onto the spectacle of LAI of alpha ERD, presumably evolving a synthesized enveloped working memory, along the virtual phase-space of Human Mind and eventually translating into the comprehensible means of communication of Humans, i.e., Language.

Alterations in Electroencephalography Theta as Candidate Biomarkers of Acute Cannabis Intoxication.

The trend toward cannabis legalization in the United States over the past two decades has unsurprisingly been accompanied by an increase in the number of cannabis users and use patterns that potentially pose wider risks to the public like driving under the influence. As such, it is becoming increasingly important to develop methods to accurately quantify cannabis intoxication and its associated impairments on cognitive and motor function. Electroencephalography (EEG) offers a non-invasive method for quantitatively assessing neurophysiological biomarkers of intoxication and impairment with a high degree of temporal resolution. Twelve healthy, young recreational cannabis users completed a series of neurocognitive tasks with concurrent EEG acquisition using the ABM STAT X24 EEG headset in a within-subject counterbalanced design. The 1-h testbed consisted of resting state tasks and tests of attention and memory. Spectral densities were computed for resting state tasks, and event-related potentials (ERPs) were obtained for the attention and memory tasks. Theta band power (3–5 Hz) was decreased during cannabis intoxication compared to placebo during resting state tasks, as were average P400 and late positive potential (LPP) amplitudes during attention and memory tasks. Cannabis intoxication was also associated with elevated frontal coherence and diminished anterior–posterior coherence in the Theta frequency band. This work highlights the utility of EEG to identify and quantify neurophysiological biomarkers from recordings obtained during a short neurocognitive testbed as a method for profiling cannabis intoxication. These biomarkers may prove efficacious in distinguishing intoxicated from non-intoxicated individuals in lab and real-world settings.

Prenatally stress-exposed male rats present lower theta prefrontal activity during attention behaviors to receptive females

Prenatal stress affects brain functionality and sexual behavior. The medial prefrontal cortex (mPFC) participates in the integration and processing of sexual stimuli. Electroencephalographic (EEG) theta activity has been associated with attention as well as rewarding and sexually motivated states. Considering that the induction of sexual motivation requires attention to, and the adequate processing of, sexual stimuli, this study aimed to evaluate the effects of exposure to stress during the prenatal period on EEG activity in the mPFC during nose pokes in adulthood, actions which are indicators of attention to a receptive female. Eighteen sexually experienced male rats were used, nine stressed prenatally by immobilization during days 14–21 of gestation (stress-exposed group). The other nine formed the control group. All rats were implanted bilaterally in the mPFC (specifically in prelimbic areas) and were allowed one intromission with a receptive female to induce a sexually motivated state before the experimental session. During this session, both nose pokes and non-contact erections in the male rats were evaluated in the presence of an inaccessible receptive female. EEGs were recorded only during nose pokes. The stress-exposed group presented lower nose poke duration, fewer non-contact erections, and lower relative power of the theta band (4–7 Hz) in both prefrontal areas. Considering that the prevalence of this band is associated with attention and motivational processes, these data confirm the deleterious effect of prenatal stress on attention and sexual activation to sexually relevant stimuli in male rats during adulthood.

Extended Visual Sequence Learning Leaves a Local Trace in the Spontaneous EEG.

We have previously demonstrated that, in rested subjects, extensive practice in a motor learning task increased both electroencephalographic (EEG) theta power in the areas involved in learning and improved the error rate in a motor test that shared similarities with the task. A nap normalized both EEG and performance changes. We now ascertain whether extensive visual declarative learning produces results similar to motor learning. Thus, during the morning, we recorded high-density EEG in well rested young healthy subjects that learned the order of different visual sequence task (VSEQ) for three one-hour blocks. Afterward, a group of subjects took a nap and another rested quietly. Between each VSEQ block, we recorded spontaneous EEG (sEEG) at rest and assessed performance in a motor test and a visual working memory test that shares similarities with VSEQ. We found that after the third block, VSEQ induced local theta power increases in the sEEG over a right temporo-parietal area that was engaged during the task. This local theta increase was preceded by increases in alpha and beta power over the same area and was paralleled by performance decline in the visual working memory test. Only after the nap, VSEQ learning rate improved and performance in the visual working memory test was restored, together with partial normalization of the local sEEG changes. These results suggest that intensive learning, like motor learning, produces local theta power increases, possibly reflecting local neuronal fatigue. Sleep may be necessary to resolve neuronal fatigue and its effects on learning and performance.

Suppression of Circadian Timing and Its Impact on the Hippocampus.

In this article, I describe the development of the disruptive phase shift (DPS) protocol and its utility for studying how circadian dysfunction impacts memory processing in the hippocampus. The suprachiasmatic nucleus (SCN) of the Siberian hamster is a labile circadian pacemaker that is easily rendered arrhythmic (ARR) by a simple manipulation of ambient lighting. The DPS protocol uses room lighting to administer a phase-advancing signal followed by a phase-delaying signal within one circadian cycle to suppress clock gene rhythms in the SCN. The main advantage of this model for inducing arrhythmia is that the DPS protocol is non-invasive; circadian rhythms are eliminated while leaving the animals neurologically and genetically intact. In the area of learning and memory, DPS arrhythmia produces much different results than arrhythmia by surgical ablation of the SCN. As I show, SCN ablation has little to no effect on memory. By contrast, DPS hamsters have an intact, but arrhythmic, SCN which produces severe deficits in memory tasks that are accompanied by fragmentation of electroencephalographic theta oscillations, increased synaptic inhibition in hippocampal circuits, and diminished responsiveness to cholinergic signaling in the dentate gyrus of the hippocampus. The studies reviewed here show that DPS hamsters are a promising model for translational studies of adult onset circadian dysfunction in humans.

The Effect of Transcranial Pulsed Current Stimulation at 4 and 75 Hz on Electroencephalography Theta and High Gamma Band Power: A Pilot Study.

Introduction: Transcranial pulsed current stimulation (tPCS) is an emerging noninvasive brain stimulation technique that has shown significant effects on cortical excitability. To date, electrophysiological measures of the efficiency of monophasic tPCS have not been reported. Objective: We aimed to explore the effects of monophasic anodal and cathodal-tPCS (a-tPCS/c-tPCS) at theta (4 Hz) and gamma (75 Hz) frequencies on theta and high gamma electroencephalography (EEG) oscillatory power. Methods: In a single-blind, randomized, sham-controlled crossover design, 15 healthy participants were randomly assigned into 5 experimental sessions in which they received a-PCS/c-tPCS at 4 and 75 Hz or sham stimulation over the left primary motor cortex (M1) for 15 min at an intensity of 1.5 mA. Changes in theta and high gamma oscillatory power were recorded at baseline, immediately after, and 30 min after stimulation using EEG at rest with eyes open. Results: a-tPCS at 4 Hz showed a significant increase in theta power compared with sham, whereas c-tPCS at 4 Hz had no significant effect on theta power. a-tPCS at 75 Hz produced no changes in high gamma power compared with sham. Importantly, c-tPCS at 75 Hz led to a significant reduction in high gamma power compared with baseline, as well as compared with c-tPCS at 4 Hz and sham stimulation. Conclusion: The results demonstrate the modulation of oscillatory brain activity by monophasic tPCS, and highlight the need for future studies on a larger scale to confirm these initial findings. Impact statement Transcranial pulsed current stimulation (tPCS) is a novel brain stimulation technique. Recently, tPCS has been introduced to directly modulate brain oscillations by applying pulsatile current over the target brain area. Using both anodal and cathodal monophasic tPCS at theta and gamma frequencies, we demonstrate the ability of the stimulation to modulate brain activity. The present findings are the first direct electroencephalography evidence of an interaction between tPCS and ongoing oscillatory activity in the human motor cortex. Our work recommends tPCS as a tool for investigating human brain oscillations and open more studies in this area.

Predicting Trial-by-Trial Variation in Oculomotor Behavior Using Multivariate Electroencephalography Theta Phase

When we interact with our environment, there is often a significant amount of variations in our behavioral responses to incoming sensory input even when inputs are identical. Variations in sensory-motor behavior can be caused by several factors, including changes in cognitive status and intrinsic neural variations in the brain. The correct identification of neural sources of behavioral variations is important for understanding the underlying neural mechanisms of sensory-motor behavior and for practical applications (e.g., the development of a precise brain-computer interface). However, studies on humans that investigate the neural sources of the trial-by-trial variation of the sensory-motor behavior are scarce. In this study, we explored the neural correlates of behavioral variations in smooth pursuit eye movements. We collected electroencephalography (EEG) activity from 15 participants while they performed a smooth pursuit eye movement task, wherein they tracked randomly selected visual motion targets that moved radially from the center of the screen. We isolated neural components that are specific to the trial-by-trial variation of smooth pursuit latency, speed, and direction using a novel multivariate pattern-analysis technique. We found that the phase of the spatially distributed multivariate theta oscillation was correlated with the trial-by-trial variation of pursuit latency and direction. This suggests that the changing patterns of the theta phase across EEG sensors can predict upcoming behavioral variations.

An attempt of complex assessment of eye-movements following perinatal ischemic

Motor functions affection is frequent consequence of ischemic stroke. Spectrum of post-stroke movement disorders often includes disturbances of eye movements. Motor functions are strongly interconnected with social abilities, including social interaction (SI). Electroencephalographic (EEG) theta activity (4–6 Hz) is thought to reflect SI in infancy. This frequency band can therefore be viewed as an indirect correlate of gaze following as a factor underlying SI. This work aims to evaluate theta power and gaze following in infants with perinatal ischemic stroke. Experimental group (EG:n = 8/mean age = 6.3 months/SD = 1.4): full-term infants with perinatal ischemic stroke in the basin of the middle cerebral artery (confirmed by MRI in the acute phase, signed information consent); control group (CG:n = 22/mean age = 5.7months/SD = 0.2): full-term typically developed infants. EEG (128-channel) background were registered in infants at the age of 5 months. EEG spectral power (4.02-5.98 Hz) was calculated using fast Fourier transform algorithm (Hanning window) in several regions, which are predominantly projected into cortical areas: premotor cortex, supplementary motor area (electrodes: 6,13,28,29,112,111,117), sensorimotor cortex (electrodes: 7,30,31,35,36,37,41,55,80,87,103,104,105,106,110). Gaze following was measured using eye tracking (CG: N = 7/ma = 5.7months/SD = 0.2; EG: N = 3/ma = 6.7months/SD = 1.7). The Mann–Whitney U test revealed significant between-group differences for premotor cortex and supplementary motor area (р = 0.016), sensorimotor cortex (p = 0.004); between-group differences in gaze following (р = 0.024). Brain injury affecting gaze following, especially during infants’ early development. It can be concluded that theta power (4–6 Hz) at least in part reflects functioning of basic anatomical substrates (predominantly cortical motor areas) of gaze following.

Phase of electroencephalography theta oscillation during stimulus encoding affects accuracy of memory recall.

Oscillatory activity is a ubiquitous property of brain signals, and yet relatively few studies have investigated how the phase of such ongoing oscillations affects our cognition. One of the main findings in this field is that the phase of electroencephalography (EEG) in the alpha band can affect perception of milliseconds-long stimuli. However, the importance of the phase of EEG for processing more naturalistic stimuli, which have a much longer duration, is still not clear. To address this question here, we presented word-nonword pairs, each of which was visible for 5 s and measured the effect of EEG phase during stimulus onset on later memory recall. The task consisted of an encoding (learning) phase in which 20 novel word-nonword pairs were presented, followed by a test phase in which participants were shown one of the seen words with four target nonwords to choose from. We found that memory recall performance was higher when the words during encoding were presented at a descending phase of the theta oscillation. This effect was the strongest in the frontal cortex. These results suggest that the phase of ongoing cortical activity can affect memorization of seconds-long stimuli that are an integral part of many daily tasks.

Administration of Alphas1-Casein Hydrolysate Increases Sleep and Modulates GABAA Receptor Subunit Expression.

Sleep is the most basic and essential physiological requirement for mental health, and sleep disorders pose potential risks of metabolic and neurodegenerative diseases. Tryptic hydrolysate of αS1-casein (αS1-CH) has been shown to possess stress relieving and sleep promoting effects. However, the differential effects of αS1-CH on electroencephalographic wave patterns and its effects on the protein levels of γ-aminobutyric acid A (GABAA) receptor subtypes in hypothalamic neurons are not well understood. We found αS1-CH (120, 240 mg/kg) increased sleep duration in mice and reduced sleep-wake cycle numbers in rats. While αS1-CH (300 mg/kg) increased total sleeping time in rats, it significantly decreased wakefulness. In addition, electroencephalographic theta (θ) power densities were increased whereas alpha (α) power densities were decreased by αS1-CH (300 mg/kg) during sleep-wake cycles. Furthermore, protein expressions of GABAA receptor β1 subtypes were elevated in rat hypothalamus by αS1-CH. These results suggest αS1-CH, through GABAA receptor modulation, might be useful for treating sleep disorders.

Electroencephalographic theta oscillatory dynamics reveal attentional bias to angry faces.

Although previous studies have reported the temporal neural dynamics (e.g., N2pc component) of threat-detection orientation for face-processing (e.g., the "anger superiority effect"), little is known about the neural oscillatory features of this phenomenon. Here, we extracted the event-related potentials and event-related oscillatory power dynamics from electroencephalographic data when participants performed a visual search task consisting of realistic angry, happy, and neutral facial expressions. We observed a shorter response time and a larger N2pc for angry faces than for happy faces, suggesting the existence of preferential processing for angry faces. Similarly, elevated theta synchronization was observed for angry faces compared to happy faces, while both angry and happy faces elicited heightened theta oscillatory activity on contralateral location of target face compared to ipsilateral location. Moreover, the theta oscillation difference negatively correlated with the amplitude of the N2pc difference. Our findings suggest that the occipital theta oscillation is engaged in the search advantage of angry facial expressions. Further, our results provide evidence that the theta oscillation may reflect the processing dynamics of threat-stimuli orientation in an ever-changing environment.

Laboratory-induced learned helplessness attenuates approach motivation as indexed by posterior versus frontal theta activity.

Research suggests that midline posterior versus frontal electroencephalographic (EEG) theta activity (PFTA) may reflect a novel neurophysiological index of approach motivation. Elevated PFTA has been associated with approach-related tendencies both at rest and during laboratory tasks designed to enhance approach motivation. PFTA is sensitive to changes in dopamine signaling within the fronto-striatal neural circuit, which is centrally involved in approach motivation, reward processing, and goal-directed behavior. To date, however, no studies have examined PFTA during a laboratory task designed to reduce approach motivation or goal-directed behavior. Considerable animal and human research supports the hypothesis put forth by the learned helplessness theory that exposure to uncontrollable aversive stimuli decreases approach motivation by inducing a state of perceived uncontrollability. Accordingly, the present study examined the effect of perceived uncontrollability (i.e., learned helplessness) on PFTA. EEG data were collected from 74 participants (mean age = 19.21 years; 40 females) exposed to either Controllable (n = 26) or Uncontrollable (n = 25) aversive noise bursts, or a No-Noise Condition (n = 23). In line with prediction, individuals exposed to uncontrollable aversive noise bursts displayed a significant decrease in PFTA, reflecting reduced approach motivation, relative to both individuals exposed to controllable noise bursts or the No-Noise Condition. There was no relationship between perceived uncontrollability and frontal EEG alpha asymmetry, another commonly used neurophysiological index of approach motivation. Results have implications for understanding the neurophysiology of approach motivation and establishing PFTA as a neurophysiological index of approach-related tendencies.

Theta and Alpha Alterations in Amnestic Mild Cognitive Impairment in Semantic Go/NoGo Tasks.

Growing evidence suggests that cognitive control processes are impaired in amnestic mild cognitive impairment (aMCI); however the nature of these alterations needs further examination. The current study examined differences in electroencephalographic theta and alpha power related to cognitive control processes involving response execution and response inhibition in 22 individuals with aMCI and 22 age-, sex-, and education-matched cognitively normal controls. Two Go/NoGo tasks involving semantic categorization were used. In the basic categorization task, Go/NoGo responses were made based on exemplars of a single car (Go) and a single dog (NoGo). In the superordinate categorization task, responses were made based on multiple exemplars of objects (Go) and animals (NoGo). Behavioral data showed that the aMCI group had more false alarms during the NoGo trials compared to controls. The EEG data revealed between group differences related to response type in theta (4–7 Hz) and low-frequency alpha (8–10 Hz) power. In particular, the aMCI group differed from controls in theta power during the NoGo trials at frontal and parietal electrodes, and in low-frequency alpha power during Go trials at parietal electrodes. These results suggest that alterations in theta power converge with behavioral deterioration in response inhibition, whereas alterations in low-frequency alpha power appear to precede behavioral changes in response execution. Both behavioral and electrophysiological correlates combined provide a more comprehensive characterization of cognitive control deficits in aMCI.

Lexical tonal discrimination in Zapotec children. A study of the theta rhythm

BackgroundZapotec is a language used mainly in the state of Oaxaca in Mexico of tonal characteristic; homophone words with difference in fundamental frequency with different meanings. Our objective was to analyze changes in the electroencephalographic (EEG) theta rhythm during word discrimination of lexical tonal bi-syllabic homophone word samples of Zapotec. MethodsWe employed electroencephalography analysis during lexical tonal discrimination in 12 healthy subjects 9-16 years of age. ResultsWe observed an increase in theta relative power between lexical discrimination and at rest eyes-open state in right temporal site. We also observed several significant intra- and inter-hemispheric correlations in several scalp sites, mainly in left fronto-temporal and right temporal areas when subjects were performing lexical discrimination. ConclusionsOur data suggest more engagement of neural networks of the right hemisphere are involved in Zapotec language discrimination.