Frontal Theta Band Research Articles

Family-based genome-wide association study of frontal θ oscillations identifies potassium channel gene KCNJ6.

Event-related oscillations (EROs) represent highly heritable neuroelectric correlates of cognitive processes that manifest deficits in alcoholics and in offspring at high risk to develop alcoholism. Theta ERO to targets in the visual oddball task has been shown to be an endophenotype for alcoholism. A family-based genome-wide association study was performed for the frontal theta ERO phenotype using 634 583 autosomal single nucleotide polymorphisms (SNPs) genotyped in 1560 family members from 117 families densely affected by alcohol use disorders, recruited in the Collaborative Study on the Genetics of Alcoholism. Genome-wide significant association was found with several SNPs on chromosome 21 in KCNJ6 (a potassium inward rectifier channel; KIR3.2/GIRK2), with the most significant SNP at P = 4.7 × 10(-10)). The same SNPs were also associated with EROs from central and parietal electrodes, but with less significance, suggesting that the association is frontally focused. One imputed synonymous SNP in exon four, highly correlated with our top three SNPs, was significantly associated with the frontal theta ERO phenotype. These results suggest KCNJ6 or its product GIRK2 account for some of the variations in frontal theta band oscillations. GIRK2 receptor activation contributes to slow inhibitory postsynaptic potentials that modulate neuronal excitability, and therefore influence neuronal networks.

Neural oscillations involved in self-referential processing

Human adults remember better trait words that are referenced to the self than those referenced to others. To investigate whether non-phase-locked neural oscillations engage in the self-reference effect, we recorded electroencephalogram (EEG) from healthy adults during trait judgments of the self and a familiar other. The wavelet analysis was used to calculate non-phase-locked time–frequency power associated with encoding of trait adjectives referenced to the self or the familiar other at theta (5–7 Hz), alpha (8–13 Hz), beta (14–27 Hz) and gamma (28–40 Hz) bands. We found that, relative to other-referential traits, self-referential traits induced event-related synchronization of theta-band activity over the frontal area at 700–800 ms and of alpha-band activity over the central area at 400–600 ms. In contrast, event-related desynchronization associated with self-referential traits was observed in beta-band activity over the central–parietal area at 700–800 ms and in gamma-band activity over the fronto-central area at 500–600 ms. Moreover, valence of traits referenced to the self and self-relevance of traits respectively led to modulations of theta/alpha- and beta/gamma-band activity. Finally, event-related synchronization of frontal theta-band activity at 700–800 ms positively correlated with the self-reference effect observed during memory retrieval. Our results indicate that non-phase-locked neural activity is involved in self-reflexive thinking. In addition, low and high-frequency neural oscillations play different roles in emotional and cognitive aspects of self-reference processing.

Neural components underlying subjective preferential decision making

The objectives of the current study were twofold: (i) to investigate the neural precursors of the formation of a subjective preference of facial stimuli, and (ii) to characterize the spatiotemporal brain activity patterns distinguishing between preferred and non-preferred faces. Multivariate EEG signals were recorded while participants made preference decisions, based on approachability, between two faces presented sequentially with unrestricted viewing time; the decision being made after presentation of the second face. The paired faces were similar in their physical properties, emphasizing the role of the subjective experience of the participants in making the decisions. EEG signals were analyzed in terms of event-related-potential (ERP) components and wavelet-based time-frequency-representations (TFR). The behavioural data showed that the presentation order and the exposure duration did not influence preference formation. The EEG data showed three effects. The earliest effect, the sustained posterior ERP positivity for preferred first faces as compared to non-preferred first faces, was found following the onset of the first face, and this was interpreted as the formation of a positive first impression of the first face. The two later effects following the second faces were an increase of frontal theta band oscillations around 500 ms for preferred second faces and of posterior gamma band oscillations around 650 ms for preferred first faces; both of which were interpreted as being related to the formation of a preference. All of these effects occurred well before the moment of conscious decision, thereby suggesting the implicitness of these neurally identifiable components.

Quantitative EEG in occupational chronic solvent encephalopathy

The aim of this study was to characterize the quantitative analyzed EEG (electroencephalogram) findings (qEEG) in chronic solvent encephalopathy (CSE) patients and study whether the qEEG findings associate with the duration and intensity of the solvent exposure. Also, the diagnostic value of qEEG in CSE is discussed. The EEG of 47 male CSE patients was analyzed. The laboratory's own reference EEG values of 24 healthy male subjects formed the laboratory control group. We also used an age-matched control group of 100 male blue-collar workers without occupational solvent exposure. The main finding of our study was that the power of the frontal theta band is increased in the CSE patient group compared with the laboratory control group. This suggests that the frontal cortex may be susceptible to the noxious effects of solvents. However, this difference was not seen in comparison with the matched control group, and thus, the connection with solvent effects remains uncertain. The variables indicating the level of solvent exposure did not associate with the power of the theta activity in the frontal area. Because of the small amount and unspecificity of the observed abnormalities, qEEG cannot be recommended to be used in the clinical diagnostics of solvent encephalopathy.

Individual differences in perceptual switching rates; the role of occipital alpha and frontal theta band activity

Prolonged presentation of visually ambiguous figures leads to perceptual switching. Individual switching rates show great variability. The present study compares individuals with high versus low switching rates by investigating human scalp electroencephalogram and blink rates. Eight subjects viewed the Necker cube continuously and responded to perceptual switching by pressing a button. Frequent switchers showed characteristic occipital alpha and frontal theta band activity prior to a switch, whereas infrequent switchers did not. The alpha activity was specific to switching, the theta activity was generic to perceptual processing conditions. A negative correlation was observed between perceptual switching and blink rates. These results suggest that the ability to concentrate attentional effort on the task is responsible for the differences in perceptual switching rates.

Linkage and linkage disequilibrium of evoked EEG oscillations with CHRM2 receptor gene polymorphisms: implications for human brain dynamics and cognition

Event-related oscillations (ERO) offer an alternative theoretical and methodological approach to the analysis of event-related EEG responses. The P300 event-related potential (ERP) is elicited through the superposition of the delta (1–3 Hz) and theta (3–7 Hz) band oscillatory responses. The cholinergic neurotransmitter system has a key function in modulating excitatory post-synaptic potentials caused by glutamate, and therefore influences P300 generation and the underlying oscillatory responses. Here we report significant linkage and linkage disequilibrium between target case frontal theta band, visual evoked brain oscillations and a single nucleotide polymorphism (SNP) from the cholinergic muscarinic receptor gene ( CHRM2) on chromosome 7. We also demonstrate significant linkage disequilibrium between CHRM2 SNPs and target case parietal delta band visual evoked oscillations (LD P<0.001). These findings were not observed for the equivalent non-target case data, suggesting a role for the CHRM2 gene in higher cognitive processing in humans.