Externally and internally controlled attention in infants: an EEG study

This work was designed to investigate EEG indices of Internally and Externally Controlled Attention in infancy. EEG was recorded in 15 infants aged 7-8 months under three experimental conditions: (1) visual attention to a new stimulation (Externally Controlled Attention or baseline condition); (2) attention guided by internal cognitive schemata during 'anticipatory' phase of the peek-a-boo game (Internally Controlled Attention); and (3) 'reappearance' phase of the peek-a-boo game when the experimenter talked and smiled to an infant (reappearance). The relative power (RP) in 4-5 single-Hz theta sub-band increased under both phases of the peek-a-boo game. The reactive changes of 4-5 single-Hz RP at prefrontal and frontal leads under the Internally Controlled Attention condition positively correlated with the total time during which an infant was able to maintain ICA. The RP in 5-6 single-Hz theta sub-band significantly increased only under the Internally Controlled Attention condition and did not correlate with the total time of this type of attention. The results support the concept of 'Diffuse Theta-Response System' that is active during expectancy and effortfully focused attention. In contrast to theta, the RP in 6-7, 7-8, and 8-9 single-Hz bands decreased during both phases of the game. The decrease was maximal at precentral leads and most probably reflected blockage of the sensorimotor (mu) rhythm due to higher motility and muscular tension in the game situation. It is concluded that EEG is an adequate vehicle for investigation of brain mechanisms of attention and voluntary control in infants.     

Poverty, cultural disadvantage and brain development: a study of pre-school children in Mexico

Forty-two children, who had been studied previously at the age of 18-30 months, were studied again at 4 years of age. Twenty-two belonged to low socioeconomic strata and were classified as high-risk children (HRC) the other 20 were classified as low-risk children (LRC), and belonged to middle and middle-high socioeconomic strata. Ten minutes of EEG using reference derivations (with linked earlobes) were recorded from each subject. Twenty EEG segments of 3.2 s each were selected by visual inspection for Fourier analysis. Absolute power (AP) was computed for the total EEG energy (1.5-19 Hz) as well as each reference derivation in 4 frequency bands: delta (1.5-3.5 Hz), theta (4-7.5 Hz), alpha (7.5-12.5 Hz) and beta (12.5-19 Hz). HRC had significantly more delta AP than LRC in frontal and central leads, and higher values of theta AP in frontal leads. Alpha AP was higher in LRC in occipital areas and in F8 and T4. This study suggests a maturational lag in HRC.     

Electrophysiological, behavioral, and subjective indexes of workload when performing multiple tasks: manipulations of task difficulty and training

This study examined whether alpha event-related desynchronization (ERD) and theta event-related synchronization (ERS) could successfully measure changes in cognitive workload and training while an operator was engaged in a continuous, interactive, control task(s). Alpha 1 (8-10 Hz) ERD, alpha 2 (10-12 Hz) ERD, and theta (3-7 Hz) ERS were determined for a communications event that occurred during multiple task workload conditions or as a single task. Other measures (alpha and theta EEG power, heart rate, respiration, eye blinks, behavioral performance, and subjective workload ratings) were also evaluated. Results showed that alpha 2 EEG, heart rate, behavioral, and subjective measures were sensitive to changes in workload in the multiple tasks. In addition, eye blink rate and behavioral measures were sensitive to training. Alpha ERD and theta ERS were not sensitive to workload and training in our interactive, multiple task environment. However, they were effective indexes of cognitive/behavioral demands within an interactive single task.     

Infants of depressed and nondepressed mothers exhibit differences in frontal brain electrical activity during the expression of negative emotions

Studies have shown that infants of depressed mothers express negative emotions more frequently than infants of nondepressed mothers. The present study examined electrical brain activity during expression of negative and positive emotions in infants of depressed and nondepressed mothers. Infants, 11 to 17 months of age, were exposed to conditions designed to elicit positive and negative emotions while electroencephalographic (EEG) activity was measured from left and right, frontal and parietal regions. EEG activity was analyzed when infants were displaying prototypic expressions of emotions. Compared with infants of nondepressed mothers, infants of depressed mothers exhibited increased EEG activation in the frontal but not parietal region when expressing negative emotions (unfelt smiles and anger). The two groups of infants did not show reliable differences is brain activation during the expression of positive emotions (happiness, surprise) or neutral expressions. Compared with infants of nondepressed mothers, infants of depressed mothers exhibit greater frontal EEG activation during the expression of negative emotions.     

EEG stability in infants/children of depressed mothers

The stability of EEG was examined in infants of depressed (BDI > 16) and non-depressed mothers (BDI < 9) from 3 months to 3 years. Of the 32 infants seen at 3 months, 15 were seen again at 3 years of age. Seven of the eight children who had exhibited right frontal EEG asymmetry as infants still showed that EEG asymmetry pattern at the 3 year visit. Children with right frontal EEG asymmetry at 3 years were observed to be more inhibited during an exploratory play task, and children of depressed versus non-depressed mothers were less empathetic during simulated maternal distress.     

Behavioral reactivity and approach-withdrawal bias in infancy.

Seven hundred seventy-nine infants were screened at 4 months of age for motor and emotional reactivity. At age 9 months, infants who showed extreme patterns of motor and negative (n = 75) or motor and positive (n = 73) reactivity and an unselected control group (n = 86) were administered the Laboratory Temperament Assessment Battery, and baseline electroencephalogram data were collected. Negatively reactive infants showed significantly more avoidance than positively reactive infants and displayed a pattern of right frontal electroencephalogram asymmetry. Positively reactive infants exhibited significantly more approach behavior than controls and exhibited a pattern of left frontal asymmetry. Results support the notion that approach-withdrawal bias underlies reactivity in infancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

EEG activity and heart rate during recall of emotional events in hypnosis: relationships with hypnotizability and suggestibility

The purpose of the present research was to find physiological and cognitive correlates of hypnosis, imaginative suggestibility and emotional experiences. After the administration of a standard hypnotic induction, the EEG and heart rate (HR) were recorded during self-generated happy and sad emotions using a relaxation condition as a control. Physiological recordings were also obtained during three eyes-open and eyes-closed baseline periods: (1) waking rest; (2) early-rest in hypnosis (just after the hypnotic induction); (3) late-rest hypnosis (at the end of hypnotic condition). EEG was recorded at frontal (F3, F4), central (C3, C4), and posterior sites (middle of O1-P3-T5 and O2-P4-T6 triangles). Using log transform of mean spectral amplitude, eight EEG frequency bands (4-44 Hz) were evaluated. High hypnotizable subjects, as compared to the lows, produced a higher theta1 amplitude (4-6 Hz) across both left- and right-frontal and right-posterior areas. These subjects also produced smaller alpha1 amplitude (8.25-10 Hz) over both left and right frontal recording sites. High suggestible subjects, during resting conditions, disclosed higher theta2 (6.25-8 Hz) and alpha1 amplitudes in eyes-closed as compared to an eyes-open condition than did low suggestible subjects. High suggestible subjects also showed, in hypnosis-rest condition, higher 40-Hz amplitudes (36-44 Hz) and HR activity than did low suggestible subjects. Hypnotizability and not suggestibility was found to moderate emotional processing: high hypnotizable individuals self-reported greater levels of emotional experiences than did low hypnotizables especially in terms of negative emotion. High hypnotizables, during processing of emotional material, also disclosed opposite 40-Hz hemispheric asymmetries over anterior and posterior regions of the scalp. These subjects during happiness showed an increased production of 40-Hz activity in the left frontal and central regions of the scalp, while during sadness they showed an increased activity in the right central and posterior regions. The hemispheric asymmetries for relaxation condition were similar, but less marked, to those obtained for happiness. No significant interactions involving both hypnotizability and imaginative suggestibility were found for physiological variables considered in this study. This demonstrates that hypnotizability and suggestibility reflect different underlying psychophysiological activities.     

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 asymmetry and heart rate during experience of hypnotic analgesia in high and low hypnotizables

This study evaluates the effects of hypnotic analgesia and hypnosis on bilateral EEG activity recorded from frontal, central and posterior areas during three painful electrical stimulation conditions: waking, hypnosis/no-analgesia, hypnosis/analgesia. Eight high-hypnotizable and eight low-hypnotizable (right handed) subjects participated in the experiment. The following measures were obtained: pain and distress tolerance ratings; EEG spectral amplitudes for the frequency bands: delta (0.5-3.75 Hz), theta 1 (4-5.75 Hz), theta 2 (6-7.75 Hz), alpha 1 (8-9.75 Hz), alpha 2 (10-12.75 Hz), beta 1 (13-15.75 Hz), beta 2 (16-31.75 Hz), total band (0.5-31.75 Hz), '40-Hz' (36-44 Hz); cardiac interbeat interval (ms); mid-frequency and high-frequency peaks from power spectral analysis of heart period variability. During hypnosis/analgesia, high hypnotizable subjects displayed significant reductions in pain and distress scores compared to hypnosis/no-analgesia and waking conditions. In each experimental condition these subjects displayed significant lower total and beta 1 amplitudes compared to low hypnotizables. High hypnotizables, on central and posterior recording sites, during both hypnosis/analgesia and hypnosis/no-analgesia conditions also showed total and delta EEG amplitude reductions in both hemispheres and a theta 1 amplitude reduction in the left hemisphere. However, for total, delta and beta 1 bands in the hypnosis/analgesia condition the amplitude reduction was more pronounced in the right hemisphere as shown by hemispheric asymmetry in favor of the left hemisphere. Low hypnotizables, on posterior recording sites, displayed a delta amplitude reduction during hypnosis/no-analgesia and hypnosis/analgesia conditions. These subjects also showed, for all recording sites, a reduction in theta 1 amplitude during hypnosis/no-analgesia compared to the waking condition. Lows, however, failed in evidencing amplitude differences between hypnosis/no-analgesia and hypnosis/analgesia conditions. During hypnotic analgesia the hemispheric asymmetry found in high hypnotizables was parallel to a significant reduction in the spectral mid-frequency peak of heart period variability which indicated a decrease in the level of sympathetic activity. In contrast, during hypnosis/no-analgesia the EEG amplitude reduction was not paralleled by a decrease in sympathetic activity.     

Workplace smoking policies in the United States: results from a national survey of more than 100,000 workers

To investigate the activity of cortical regions in the control of movement, we studied event-related desynchronization/synchronization (ERD/ERS), event-related coherence (ERC), and phase coherence in 29-channel EEGs from 9 subjects performing self-paced movements of the right index finger. Movement preparation and execution produced ERD over the sensorimotor areas at 10 Hz and 20 Hz, followed by ERS. ERD corresponded spatiotemporally to an increase in coherence over the frontocentral areas. For both frequency bands, ERD began over the left sensorimotor areas and became bilateral at the time of movement onset. The coherence increase with frontal areas began in the left central areas and became symmetrical after EMG onset. The ERD and coherence increase was longer at 10 Hz than at 20 Hz. Phase coherence at 10 Hz showed a lead of anterior regions to posterior regions throughout the time period, and at 20 Hz showed a tendency toward zero phase delay corresponding with the movement. EEG desynchronization parallels functional coupling over sensorimotor and frontal areas. Event-related coherence and phase coherence findings implicate the frontal lobes in control of movement planning and execution. The involvement of different frequency bands with different timings may represent parallel changes in the cortical network.     

EEG activation in 1-month-old infants of depressed mothers

Previous research has documented differences in the pattern of EEG activation between 3-month-old infants of depressed mothers and infants of nondepressed mothers. In the present study, EEG was recorded in even younger 1-month-old infants of depressed and nondepressed mothers. The infants of depressed mothers exhibited greater relative right frontal EEG asymmetry (due to reduced left frontal activation), and this pattern at 1 month was significantly related to 3-month EEG asymmetry. Right frontal EEG asymmetry was also related to more frequent negative facial expressions (sad and pre-cry faces) during the Brazelton exam. Finally, the infants of depressed mothers showed more indeterminate sleep, were less active, and cried less than infants of nondepressed mothers.     

Human electroencephalographic (EEG) response to olfactory stimulation: two experiments using the aroma of food

The present studies sought to examine the effect of olfactory stimulation on human Central Nervous System activity. In the first experiment (n = 21), EEG response to the 'synthetic' odours of chocolate, spearmint, almond, strawberry, vegetable, garlic and onion, and cumin or no odour was recorded from 19 electrodes (F3, F4, F7, F8, Fz, T3, T4, T5, T6, P3, P4, Pz, O1, O2, C3, C4, Cz) in all EEG frequencies (delta, theta, alpha, beta1 and beta2). Exposure to the odour of chocolate was associated with significant reductions in theta activity when compared with the odours of almond and cumin, with a trend towards significance when compared with no-odour control. Exposure to the odour of spearmint was associated with a significant reduction in EEG theta when compared with the no-odour control. No significant effects were observed in other frequencies. In a second experiment (n = 15), EEG response to the odours of real foods (chocolate, baked beans, rotting pork) and two controls (no odour and hot water) was recorded as in Experiment 1. The odour of chocolate was associated with significantly less theta activity than was any other stimulus. It is hypothesised that the alterations in theta reflect shifts in attention or cognitive load during olfactory perception, with a reduction in theta indicating a reduced level of attention.     

Studies on integrative functions of the human frontal association cortex with MEG

Our MEG studies on the human frontal association cortex are briefly reviewed. (1) The no-go potential was first found at go/no-go reaction-time hand movement task with discrimination between different colour light stimuli in the prefrontal cortex of monkeys. The potential was recorded in human subjects with EEG over the scalp, but its current dipoles could be localized only by use of MEG, in the dorsolateral part of the frontal association cortex in both cerebral hemispheres. The function for no-go decision and subsequent suppressor action was thus substantiated in the human frontal cortex. (2) Utterance of a short noun in Japanese was found to be initially preceded by an activity in the lower lateral part of the frontal lobe and then by that around the central sulcus. The area of the former, often in both hemispheres, appears to correspond to Broca's motor speech centre and that of the latter, always in both hemispheres, to correspond to the motor-somatosensory cortices. (3) Intensive and continuous concentration on mental calculation and some 'abstract' thinking for a few minutes were often associated with magnetic theta (5-7 Hz) wave bursts in the frontal part of the scalp. Dipole fitting suggested that the electrical current dipoles occur successively and scattered in wide areas of the frontal lobe on both sides. They are to be called "frontal mental theta wave", revealing dynamic and active participation of the frontal lobe in mental functions.     

Frontal brain asymmetry predicts infants' response to maternal separation.

Examined whether certain features of infant temperament might be related to individual differences in the asymmetry of resting frontal activation. EEG was recorded from the left and right frontal and parietal scalp regions of 13 normal 10-month-old infants. Infant behavior was then observed during a brief period of maternal separation. Those infants who cried in response to maternal separation showed greater right frontal activation during the preceding baseline period compared with infants who did not cry. Frontal activation asymmetry may be a state-independent marker for individual differences in threshold of reactivity to stressful events and vulnerability to particular emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tocopherol concentrations in adipose tissue. Relationships of tocopherol concentrations and fatty acid composition in serum in a reference population of Swedish men and women

The differences in EEG theta waves between concentrative and non-concentrative Qigong states were studied by means of power spectrum analysis and EEG mapping. The adult subjects included 20 practitioners of concentrative Qigong, 30 practitioners of non-concentrative Qigong and 23 control subjects. The results showed frontal mid-line theta rhythm was related to concentrative Qigong state. As the theta rhythm has been suggested to be one of the normal EEG patterns occurring in mental concentration, it is concluded that the theta rhythm is an indicator of mental concentration during Qigong state. This finding clarifies the implication of the theta rhythms appearing in Qigong and other meditation.     

The similarity and difference between dogs assessed by the indices of the summary electrical activity of the frontal cortex, hippocampus, amygdala and hypothalamus

Eight dogs were bilaterally implanted with stainless steel electrodes in dorsal and ventral hippocampi (DHp, VHp), basolateral amygdala (BLA), lateral hypothalamus (LH) and with silver spherical electrodes in the frontal cortex (FC). The EEG of these structures was recorded in the state of wakefulness without any stimulation. Rhythmical activity in the theta (4.4 +/- 0.05 Hz) and alpha (10.7 +/- 0.2 Hz) ranges was revealed in all the dogs. Rhythm of the beta-2 range (22.4 +/- 0.1 Hz) was recorded in four, and that of the beta-3 (37.8 +/- 0.5 Hz) only in two of the animals. The mean frequency of the theta-rhythm recorded in the LH was higher (p < 0.001) than that in the VHp and AMB. The spectral density in the theta range was higher in the VHp than that in the other structures (p < 0.01). The same values for the DHp and AMB were higher that for the LH (p < 0.001) and FC (p < 0.01). The spectral densities in the right DHp and VHp were higher than in the symmetrical left derivations (p < 0.001). The dogs were different in the expression of specific rhythms, their frequency and power. These characteristics depended on the degree of emotional excitation and motor activity of the dogs during recording of the electrical activity.     

Behaviour-related effects of nicotine on slow EEG waves in basal nucleus-lesioned rats

The basal magnocellular nucleus is assumed to play a crucial role in cholinergic activation of the cortical EEG. The aim of this study was to establish whether intraperitoneally applied nicotine may counteract the power asymmetry of the slow waves in the cortical EEG of both hemispheres after an unilateral lesion in the basal nucleus. In 17 rats the basal nucleus (substantia innominata/ventral pallidum) was unilaterally lesioned by ibotenic acid. The lesion produced unilateral power increases of all frequencies up to 20 Hz in the frontal EEG that increased with higher arousal level. Additionally, synchronized spike and wave discharges appeared in the frontal EEG. The results indicate that the basal nucleus suppresses especially the delta EEG waves in the frontal motor cortex during motor active behaviour. Nicotine (0.1 and 1 mg/kg) partially counteracts the power asymmetry of frontal slow waves (2-6 Hz) only during exploratory sniffing but not during grooming and waking immobility. Physostigmine (1 mg/kg) was also effective during exploratory sniffing. The results may indicate a role of nicotinic mechanisms in the information input component of exploratory behaviour.     

Rol' of the frontal lobe in synchronizing biopotentials in different regions of the dog brain

The role of the frontal cortex in formation of neocortical systemic processes has been studied by the method of sign correlation of the summate electrical activity. A distant EEG synchronization in the temporal and occipital zones sets in following strychninization of F2 zones (but not of Prc2 zones) in anaesthetized dogs or in cerveau isolé preparations. In dogs with elaborated conditioned reflexes a statistically significant distant synchronization of the neocortical EEG sets in during the delay period only in case of well expressed motivation (of hunger in case of food reinforcement, and of thirst in case of water reinforcement). No distant conditioned EEG synchronization was revealed in lobectomised dogs. The role of the frontal cortex in the intracerebral integration is discussed which is necessary for achievement of the forthcoming signal activity.