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M R Cook

Publications and source records attributed to M R Cook.

At least 37 records · Page 2Linked to original sources
PubMed1995

Smoking and EEG power spectra: effects of differences in arousal seeking.

Reversal theory, a general theory of motivation, emotion and action, has recently been shown to predict lapses in smoking cessation. Individuals are less likely to lapse if they are in the telic (serious-minded, arousal avoidant, goal-oriented) state than when they are in the paratelic (playful, arousal seeking, spontaneous) state. The literature indicates that people can smoke in such a way as to either increase or decrease central nervous system arousal; smoking in the telic and paratelic states might therefore differentially affect the resting electroencephalograph, as quantified by Fast Fourier Transform analysis. The basic hypothesis was supported. Theta power was decreased when subjects in the telic state smoked, while beta 2 power was increased when subjects in the paratelic state smoked; the latter finding was, however, true only for men. The results have important implications for research on changing health behaviors and for smoking cessation programs.

Adolescent↗
PubMed1995

Reversal theory's mastery and sympathy states in smoking cessation.

Relapse is the most frequent outcome of smoking cessation attempts. This study tests the usefulness of the mastery and sympathy concepts of Apter's reversal theory to explain whether subjects lapse or abstain during highly tempting situations. Descriptions of the highly tempting situations of 57 individuals who were attempting to quit smoking were assigned to mastery or sympathy categories. Situations were also coded for availability of cigarettes. Logit modeling revealed that both the mastery/sympathy variable and the availability of cigarettes were necessary to fit the data. Being in the mastery state and having to exert effort to get cigarettes were significantly related to resisting the urge to smoke. The smoking status of 36% of the subjects was correctly classified using both variables. The usefulness of mastery/sympathy states in explaining relapses in behavior change is discussed.

Adult↗
PubMed1994

Dose response study of human exposure to 60 Hz electric and magnetic fields.

This human exposure study examined the relationship between field strength and biological response and tested whether the exposure levels at which the greatest effects occur differ for different endpoints. Three matched groups of 18 men each participated in two 6 h exposure test sessions. All subjects were sham exposed in one session. In the other session, each group of subjects was exposed at a different level of combined electric and magnetic field strength (low group:6 kV/m, 10 microT; medium group:9 kV/m, 20 microT; and high group: 12 kV/m, 30 microT). The study was performed double blind, with exposure order counterbalanced. Significant slowing of heart rate, as well as alternations in the latency and amplitude of event-related brain potential measures derived from the electro encephalogram (EEG), occurred in the group exposed to the 9 kV/m, 20 microT combined field (medium group). Exposure at the other field strength levels had no influence on cardiac measures and differential effects on EEG activity. Significant decrements in reaction time and in performance accuracy on a time estimation task were observed only in the low group. These results provide support for the hypothesis that humans may be more responsive to some combinations or levels of field strength than to others and that such differences in responsivity may depend, in part, on the endpoint of interest.

Action Potentials↗
PubMed1992

ELF exposure facility for human testing.

A laboratory facility specifically designed for controlled human exposure to 60-Hz electric (0 to 16 kV/m) and magnetic (0 to 32 A/m, B = 0 to 40 microT) fields has been constructed. The facility presents uniform fields under controlled temperature and humidity. Special control systems allow collection of physiological data during, as well as before and after, exposure to electric fields at strengths to 16 kV/m under verified double-blind control. Exposure to continuous or intermittent fields is possible in the facility. The capability of obtaining physiological data during actual exposure to constant or intermittent, 60-Hz fields, and of doing so without either the subject or the experimenter being aware of actual field conditions, is a critical factor in valid experimentation.

Electromagnetic Fields↗
PubMed1992

A replication study of human exposure to 60-Hz fields: effects on neurobehavioral measures.

The purpose of this study was to reproduce and extend an earlier investigation of the effects of human exposure to combined, 60-Hz electric and magnetic fields. This paper presents the neurobehavioral results. Thirty men participated in one training session and four testing sessions. Subjects were randomly assigned to two groups. The 18 subjects in Group I were exposed (9 kV/m, 20 microT) and sham exposed in two counterbalanced orders. In Group II, half of 12 subjects were exposed (9 kV/m, 20 microT) every session, and the remaining half were sham exposed every session. The study was doubly blinded. Measures of cardiac interbeat interval, event-related brain potentials, and performance were obtained before, during, and after exposures. As in the earlier study, exposure to the combined field resulted in a statistically significant slowing of heart rate, in changes in late components of event-related brain potentials, and in decreased errors on a choice reaction-time task. In addition, field effects on several other measures approached statistical significance. The physiological measures obtained during exposure indicated that effects were greatest soon after the field was switched on, and again when it was switched off. The data indicate that changes in exposure level may be more important than duration of exposure for producing effects in human beings.

Adult↗
PubMed1991

State-outcome consistency in smoking relapse crises: a reversal theory approach.

Previous investigations of smoking relapse crises have found limited within-subject consistency. Several investigators have suggested that greater consistency might be observed if situations were described phenomenologically. Reversal theory provides one phenomenological framework. Two relapse crises from each of 49 ex-smokers were compared, using reversal theory constructs. Maintaining abstinence in both crises was consistently associated with being in serious-minded (telic) and conformist states. Smoking in both crises was consistently associated with being in playful (paratelic) or negativistic states. Crises with different outcomes occurred in different state combinations. The findings suggest that coping strategies should be state-tailored for optimal effectiveness.

Adaptation, Psychological↗
PubMed1991

Effects of methanol vapor on human neurobehavioral measures.

Methanol could become an important motor fuel. The objective of this exploratory study was to provide preliminary information about whether or not acute exposure to methanol at 250 mg/m3 for 75 minutes would have adverse effects on human neurobehavioral functions important in everyday life. This concentration level was selected because it is at the upper limit of the traffic scenario estimates provided by the U.S. Environmental Protection Agency (EPA)2 (86 to 240 mg/m3), but is below the maximum concentrations for eight-hour average exposures currently recommended by the National Institute of Occupational Safety and Health (NIOSH) and the American Conference of Government and Industrial Hygienists (ACGIH) (260 mg/m3). Although traffic scenario exposure estimates suggest that such high levels of exposure last less than 15 minutes, we used a 75-minute exposure to increase the probability of identifying dependent measures that should be studied in more detail in a future confirmatory study. Twelve healthy young men, each serving as his own control, participated in two sham exposures and two methanol exposures under counterbalanced, double-blind control conditions. Because methanol is present in many foods, and because high preexposure levels of methanol or formate might obscure exposure effects, subjects were required to strictly limit their diets for 12 hours before each experimental session. The following endpoints were examined before, during, and after exposure to methanol and sham vapors: blood and urinary methanol; plasma formate; oral temperature; blood pressure; subjective mood, alertness, fatigue, workload, and symptom scales; spectral analysis of the electroencephalogram; visual- and auditory-event-related potentials; contingent negative variation; respiration; cardiac interbeat interval; Symbol Digit substitution task; three-choice reaction time; Stroop color-word test; simple reaction time; visual function; critical flicker fusion frequency; hand steadiness; visual search task; Gamberale reaction time task; visual tracking task; Sternberg memory task; interval production task; and speeded addition task. Two dual tasks were also included in the task batteries. These endpoints were selected from those indicated in the literature to be sensitive to solvents, and from those that are widely used in other neurobehavioral test batteries to identify the effects of environmental pollutants. Because the number of endpoints examined was large and the number of subjects was small, procedures designed to reduce the number of statistical tests performed were used. Mean methanol concentration in the exposure room during methanol exposures was 249 mg/m3 (SD +/- 7 mg/m3). Exposure produced significant increases in blood and urine methanol concentration. As expected, no changes in plasma formate were observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Measurement of salivary thiocyanate during the process of smoking cessation.

The changes in salivary thiocyanate (SCN) following smoking cessation were determined for 70 people recruited from community-based smoking cessation programs. Data collected over 3 months following cessation showed a half value of 5 days for abstainers, a strong linear relationship between SCN level and number of days since quitting, and considerable individual variation in precessation SCN level. It is concluded that SCN has value as an inexpensive, initial screening test of smoking behavior.

Humans↗
PubMed1990

Reversal theory and smoking: a state-based approach to ex-smokers' highly tempting situations.

Reversal theory provides a new approach to understanding ex-smokers' behavior during highly tempting situations. Hypotheses derived from the theory were tested in 2 studies of the highly tempting situations of ex-smokers drawn from community smoking cessation programs. Study 1 consisted of interviews with 55 Ss (25 men and 30 women, mean age 37 years) conducted 3 months after cessation. Study 2 consisted of interviews with 104 Ss (45 men and 59 women, mean age 41 years) conducted 6, 9, 12, and 15 months after cessation. All interviews were coded using reversal theory constructs. Results supported the hypotheses that individuals in paratelic or negativistic states were more likely to lapse than individuals in telic/conformist states and that cigarette availability was related to lapses in paratelic, but not telic, states. Reversal theory constructs accurately classified 93% and 85% of the cases, suggesting that the theory provides an improved model for understanding behavior during highly tempting situations.

Adult↗
PubMed1988

The influence of salivary stimulation on the validity of thiocyanate as an index of smoking status.

This study investigated the effects of salivary stimulation on thiocyanate (SCN) levels. A device for collecting parotid saliva that allowed for the measurement of flow rate was used in stimulated and nonstimulated conditions with six subjects. Results indicated that SCN levels exhibited considerable within-subject variability and were inversely related to flow rate. Under stimulated conditions, SCN levels stabilized in 3 min. Under nonstimulated conditions. SCN levels stabilized in 26 min. Although mean SCN levels were higher for smokers than nonsmokers, considerable overlap was observed such that misclassification of both smokers and nonsmokers could occur if cut-off points were not adjusted for flow rate conditions. Suggestions for standardizing stimulated conditions for collecting salivary SCN samples are discussed.

Adult↗
PubMed1988

Exercise testing in the evaluation of human responses to powerline frequency fields.

The present study used exercise testing to examine the effects of 60-Hz electric and magnetic field exposure. Eleven males, 21-29 years, were tested during four experimental sessions (counterbalanced order and double-blind design). These included either 45-min exercise (50% of VO2 max) or no-exercise periods followed by either real field (9-kV/m, 16-A/m) or sham exposure for 2 h in a 60-Hz human exposure facility. Exercise produced a decrease in plasma volume and increases (p less than 0.05) in lactic acid, cortisol, growth hormone and testosterone levels, but these were not different under real and sham field conditions during the 2-h recovery periods. During no-exercise sessions, cardiac interbeat interval was increased (p less than 0.05), i.e., heart rate was slower, when subjects were exposed to real fields. Our results suggest that future studies should focus on evaluation of the effects of 60-Hz fields on the entire process of exercise-induced activation and recovery.

Adult↗
PubMed1987

Evaluation of salivary thiocyanate as an indicator of smoking behavior.

Salivary samples from three placement sites and under stimulated and unstimulated flow-rate conditions were collected from 36 participants (18 smokers, 18 nonsmokers) on each of 3 days. These samples were used to determine the best collection methodology for discriminating smokers from nonsmokers, the reliability of salivary thiocyanate (SCN) over days, and the stability of SCN given varying storage treatments. Results showed that SCN levels were significantly higher in smokers than in nonsmokers, in parotid site collections than either sublingual or mixed collections, and in unstimulated collections. Stimulated, mixed samples were reliable across days and were the best discriminator of smokers and nonsmokers. SCN levels did not differ under varying storage treatments. It is recommended that a standard methodology for collecting stimulated, mixed saliva be used when measuring SCN levels.

Female↗
PubMed1986

Effects of variation in physical effort on frontalis EMG activity.

The physiological mechanisms underlying forehead muscle biofeedback for stress reduction are not well understood. A common hypothesis considers the frontales to be "key muscles" uniquely indexing the degree of tension present in the general musculature. We tested this hypothesis under conditions ranging from relaxation to maximum physical effort. The hypothesis was not supported. Changes in forehead muscle activity were limited primarily to reflecting changes in head and neck muscle tension.

Adult↗
PubMed1983

Melanotic neuro-ectodermal tumour of infancy. A case report.

A case of melanotic neuro-ectodermal tumour of infancy (retinal anlage tumour, melanotic ameloblastoma) is described. Although a well recognized entity, the biological origin of this tumour is still disputed. A confusing array of names has been awarded to this tumour which characteristically occurs in infants under one year of age, commonly arising from the maxilla but also from the mandible, frontal bone, mediastinum, shoulder and cerebellum. While the origin of the tumour remains unclear, the ultra-structural evidence of Haywood et al. (1969) supports a neural crest origin. Consistent with this are the findings by Borello and Gorlin (1966) of high urinary vanillylmandelic acid excretion in one case and the correlation of tumour enzyme patterns with those of paragangliomas, neuroblastomas and phaeochromocytomas.

Humans↗