Biomedical subjects

N A Fox

Publications and source records attributed to N A Fox.

9 recordsLinked to original sources

PubMed1992

Electroencephalogram asymmetry during emotionally evocative films and its relation to positive and negative affectivity.

The purpose of the present study was to determine if there were differences in hemispheric lateralization during the experience of emotions and if those differences were related to personality style. College-age adult subjects selected for high positive and negative affectivity on Tellegen's Multidimensional Personality Questionnaire (MPQ; Tellegen, 1982) viewed video stimuli selected for their emotionally evocative nature and rated the intensity of the emotions they experienced. The ongoing electroencephalogram (EEG) was recorded while they watched the video clips. Analyses of the EEG data revealed that there were differences in regional activation during the emotional video clips, especially for those stimuli selected to elicit either happy or disgust emotions. These results support the hypothesis that the right hemisphere is specialized for the experience of certain negative affects, whereas the left hemisphere is specialized for the experience of certain positive affects. The findings also indicated some support for the theory that individual differences in personality style are related to differing levels of hemispheric arousal.

Adolescent↗

PubMed1992

An easily removable ceramic bracket?

The use of ceramic brackets in fixed appliance orthodontics has highlighted several problems, amongst which are the problems of enamel damage and possible trauma to the patient during debonding. A ceramic bracket has recently been developed with a polycarbonate laminated base (Ceramaflex) claiming to make debond much easier, although there are no independent data to substantiate this claim. The in-vitro bond strength of these ceramic brackets to enamel was tested and compared with metal standard Edgewise brackets. The bond produced with the Ceramaflex bracket was similar in magnitude, but less reliable. No fracture of the bracket or damage to enamel was seen during debonding. Debonding of these brackets was easy to carry out, but it is possible that more debonds may occur during treatment than with the use of metal brackets.

Adhesives↗

PubMed1992

The relations between frontal brain electrical activity and cognitive development during infancy.

The relations between changes in the scalp-recorded electroencephalogram (EEG) and the development of the ability to perform successfully 2 cognitive tasks attributed to frontal lobe functioning were examined in 13 infants from 7 to 12 months of age. Infants successful in performing the A-not-B task with increasingly longer delays across the second half of the first year of life showed changes in power in scalp-recorded brain electrical activity in the frontal region and an increase in anterior/posterior EEG coherence. Infants with rapid mastery of object retrieval did not differ in frontal EEG development from infants who exhibited the normal developmental progression in object retrieval performance. In a task examining inhibition of reaching to a novel toy, there were no differences in frontal EEG as a function of performance. Results from a cross-sectional sample revealed similar findings. These data confirm work with nonhuman primates on the importance of maturation of frontal cortex in the successful performance on certain tasks (A-not-B), but do not confirm nonhuman primate data on the importance of frontal cortex for other tasks (object retrieval). The data also suggest that the electroencephalogram may be useful as a noninvasive measure of central nervous system development during the first year of life.

Brain↗

PubMed1992

The relations among infant temperament, security of attachment, and behavioral inhibition at twenty-four months.

The purpose of this study was to examine the relations among infant temperament, attachment, and behavioral inhibition. 52 infants were seen at 2 days, 5, 14, and 24 months of age. Assessments were made of temperament at 2 days and 5 months of age, and attachment and behavioral inhibition were assessed at 14 and 24 months, respectively. EKG was recorded at each assessment, and measures of heart period and vagal tone were computed. Distress to pacifier withdrawal at 2 days of age was related to insecure attachment at 14 months. 2 types of distress reactivity at 5 months, reactivity to frustration and reactivity to novelty, were identified and related to high vagal tone. Attachment classification at 14 months was directly related to inhibited behavior at 24 months. Infants classified as insecure/resistant were more inhibited than those classified as insecure/avoidant. In addition, an interaction of infant reactivity to frustration and attachment classification was found to predict inhibition at 24 months. Infants classified as insecure/resistant and who had not cried to the arm restraint procedure at 5 months were the most inhibited at 24 months. These findings are discussed in terms of hypotheses regarding multiple modes of distress reactivity and regulation in early infancy and their different social and behavioral outcomes.

Child Behavior↗

PubMed1991

If it's not left, it's right. Electroencephalograph asymmetry and the development of emotion.

Recent studies suggest that an initial component involving stimulus evaluation may precede subsequent steps in the generation of emotion. This article presents a model for the development of emotion that involves an initial decision of approach or withdrawal, which results in motor programs, including facial expression, that facilitate either approach or withdrawal. With development, more complex emotions arise, as products of these basic initial responses and interaction with the environment. Evidence is presented that suggests that there are brain asymmetries (as measured by scalp recorded EEG activity) localized to the frontal region that are associated with the generation of emotion in infants. Variability in the pattern of EEG asymmetry between infants may be an important marker of differences in temperament.

Cerebral Cortex↗

PubMed1991

Bond strengths of orthodontic bonding materials: an in-vitro study.

The shear bond strength of a conventional composite resin was compared in-vitro with the bond strength of a fluoride releasing composite and a glass ionomer cement. The results obtained showed that the conventional composite had the highest mean bond strength. The results were also analysed using the Weibull analysis which examines bond reliability rather than mean bond strength. It is likely that the two composites will behave in a similar manner in the clinical situation.

Acid Etching, Dental↗

PubMed1991

Attachment to mother/attachment to father: a meta-analysis.

An important tenet of attachment theory is that classification of security or insecurity as derived from the Strange Situation reflects the quality of an infant's relationship with its caregiver. One piece of evidence supporting this claim is the lack of concordance of classification between an infant and its mother and father. We performed a meta-analysis of the 11 studies that have examined the concordance of mother/father attachment to an infant. We found that security of attachment to one parent was dependent upon security to the other parent, that type of insecurity (avoidant/resistant) to one parent was dependent upon type of insecurity to the other, and that subcategory classification within the secure category (B1B2/B3B4) to one parent was dependent upon subcategory classification to the other. These data raise important questions regarding the meaning of infant attachment classification as derived from the Strange Situation. Among the possible explanations for the pattern of data are existence of concordant parenting styles and/or influence of infant temperament (possibly the tendency to cry upon separation) on classification of security/insecurity in the Strange Situation.

Child↗

PubMed1990

Electrophysiological indices of frontal lobe development. Relations to cognitive and affective behavior in human infants over the first year of life.

Over the past 8 years we have been involved in a study of the psychophysiological correlates of cognitive and affective behaviors during the first year of life. We have utilized recordings of brain electrical activity (the EEG) to describe differences in regional activation as well as, more recently, changes in regional connectivity. Our studies have indicated an important role for the frontal region in the expression of positive and negative emotions and in the regulation of emotional distress. In addition, individual differences in frontal EEG maturation seem to be associated with improved performance on tasks known to involve specific regions of frontal cortex. The corroborative data from different areas of study (studies of brain-damaged adults; studies of lesions in nonhuman primates) give us confidence that our measures of regional electrical activity are indeed reflecting true brain processes. Our continuing task is to understand the skills that are involved in these complex behaviors (such as AB performance or expression of affect) so as to better understand these important brain-behavior relationships.

Aging↗

PubMed1990

Fluoride release from orthodontic bonding materials. An in vitro study.

Decalcification of enamel continues to be a problem with fixed orthodontic appliances. An orthodontic bonding composite is now available which claims to release fluoride, although there are no data to substantiate this claim. Fluoride release from this new material (DIRECT) was measured and compared with two other orthodontic bonding materials. The amount of fluoride released was very small and unlikely to have a therapeutic effect.

Color↗