Beta frequency

Electrophysiological Tobacco smoking produces cortical activation on the EEG. Broadly, it reduces slow-wave activity (theta and delta) and increases activity in alpha and beta frequency bands (Knott et al. 1998 Pritchard et al. 1999). Other studies have found more isolated effects in alpha frequencies (Domino and Matsuoka 1994 Foulds et al. 1994). 

Figure 8 Mean changes over baseline in percentage of EEG amplitude falling in the beta frequency range (13-30 cycles/sec) during each of the five trials, as discussed in the text and in Fig. 4. Abbreviations EEG, electroencephalographic TRZ, triazolam CLAR, clarithromycin ERY, erythromycin AZ, azithromycin PL, placebo. Source From Ref. 77.

This rather straightforward chain of situation-reaction relationship can be modified by characteristics of the situation such as additional emotional load caused by danger or time pressure. The "effort" system has the property to disconnect Arousal Systems 1 and 3 to prevent immediate action and dlitate deliberate analysis performed by certain cortical-subcortical brain circuits (Gray, 1982). However, Arousal System 1 facilitates the focusing of attention to the situational demands. In this case, an increase of spontaneous, nonstimulus-specific EDRs will indicate an emotional load that comes with the situation (Fowles, 1980). The ongoing central information processing will be reflected both by the dominance of the beta frequency band over the alpha band in the EEG and a decrease in heart rate variabihly (HRV). 

In Fig. 4, NEUT means that the participants in the study were experiencing neutral emotions, NEG indicates that they were experiencing negative emotions, while POS indicates that they were experiencing positive emotions. The black color in the brain map of Fig. 4 illustrates higher power values, while the light gray color indicates lower values. There are four power values from different frequency bands which include the theta, alpha 1, alpha 2, and beta frequencies illustrated in the research of Aftanas et al. (1998). The results of their research provide evidence that the EEG power values of different brain maps could indicate different human emotions. 

In patterns containing small symmetrical, continuous repeating square shapes, higher Theta and Alpha brain frequencies were found, which exhibits lower level of alertness, promoting a calm response, whilst asymmetrical patterns with irregular random intense blocks exhibit high Beta frequency in the visual brain, which indicates high arousal with increased emotional excitement. 

Symmetrical patterns with regularly repeating large square shapes exhibit lower Beta frequencies, which is related to calmness. Patterns of the same squares but nonrepeating, irregularly intense and smaller trigger higher arousal and excitement, which is also consistent with self-evaluation. 

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