Eye blink startle responses in behaviorally inhibited and uninhibited children

The present study examined the startle reflex as a physiological marker of behavioral inhibition. Participants were 7to 12-year-old children who had been previously identified as inhibited or uninhibited as part of an ongoing longitudinal study on the role of behavioral inhibition in the development of anxiety disorders. Analysis of their scores on the Behavioral Inhibition Scale revealed that the children were stable in their behavioral inhibition categorization as compared to the beginning of the longitudinal study. An experiment was carried out to study startle modulation effects in response to novel and familiar pictures of threatening and non-threatening facial expressions in inhibited and uninhibited children. The main results can be summarized as follows. To begin with, no modulation effect was found. That is, children did not show the expected (adult-like) startle facilitation while viewing unpleasant pictures. Second, a habituation effect was found: that is, during the testing phase children responded more intensely to the first block of slides than to the second block of slides (irrespective of slide content). Third, unexpectedly behaviorally inhibited children displayed smaller eye blink magnitudes in response to novel slides than uninhibited children. Fourth and finally, no meaningful differences were found in the patterns of startle responses of both genders.

The Role of Temperament in the Etiopathogenesis of Bipolar Spectrum Illness

Bipolar disorder constitutes a challenge for clinicians in everyday clinical practice. Our knowledge concerning this clinical entity is incomplete, and contemporary classification systems are unable to reflect the complexity of this disorder. The concept of temperament, which was first described in antiquity, provides a helpful framework for synthesizing our knowledge on how the human body works and what determines human behavior. Although the concept of temperament originally included philosophical and sociocultural approaches, the biomedical model is dominant today. It is possible that specific temperaments might constitute vulnerability factors, determine the clinical picture, or modify the course of illness. Temperaments might even act as a bridge between genes and clinical manifestations, thus giving rise to the concept of the bipolar spectrum, with major implications for mental health research and treatment. More specifically, it has been reported that the hyperthymic and the depressive temperaments are related to the more "classic" bipolar disorder, whereas cyclothymic, anxious, and irritable temperaments are related to more complex manifestations and might predict poor response to treatment, violent or suicidal behavior, and high comorbidity. Incorporating of the concept of temperament and the bipolar spectrum into the standard training of psychiatric residents might well result in an improvement of everyday clinical practice.

Childhood predictors of states of anxiety

Development of the characteristics of social phobia often requires a diathesis in the form of a temperamental bias. A behavioral profile marked by vigorous motor activity and crying to unfamiliar stimuli at 4 months of age - called high reactivity- is characteristic of about 20% of healthy, Caucasian infants. This pattern predicts shy behavior in preschool children and symptoms of social anxiety at age 7, and, at age 11, a subdued personality and biological features that are consonant with a hypothesis of amygdalar excitability. The biological variables that best characterize the children who had been high-reactive infants are right-hemisphere activity in the electroencephalogram (EEC), a larger evoked potential from the inferior colliculus, higher sympathetic tone in the cardiovascular system, and larger event-related potentials to discrepant stimuli. About a quarter of 11-year-olds who had been high reactives displayed behavioral and biological characteristics that are in theoretical accord with the hypothesis of amygdalar excitability, while only 1 of 20 displayed a profile characterized by features in opposition to their temperament. The evidence points to a modest temperamental contribution to the development of symptoms currently regarded as diagnostic of social phobia.

Electrophysiological responses to auditory novelty in temperamentally different 9-month-old infants

Behavioral reactivity to novel stimuli in the first half-year of life has been identified as a key aspect of early temperament and a significant precursor of approach and withdrawal tendencies to novelty in later infancy and early childhood. The current study examines the neural signatures of reactivity to novel auditory stimuli in 9-month-old infants in relation to prior temperamental reactivity. On the basis of the assessment of behavioral reactivity scores at 4 months of age, infants were classified into groups of high negatively reactive and high positively reactive infants. Along with an unselected control group, these groups of temperamentally different infants were given a three-stimulus auditory oddball task at 9 months of age which employed frequent standard and infrequent deviant tones as well as a set of complex novel sounds. In comparison to high positively reactive and control infants, high negatively reactive infants displayed increased amplitude of a positive slow wave in the ERP response to deviant tones compared to standard tones. In contrast, high positively reactive infants showed a larger novelty P3 to the complex novel sounds. Results are discussed in terms of optimal levels of novelty for temperamentally different infants.

Brainstem correlates of defensive states in humans

BACKGROUND

Brainstem auditory evoked potentials (BAEP) reflect the activation of brainstem nuclei in the first milliseconds after presentation of an auditory stimulus. These electrophysiological correlates of neural processing are highly automatic and not influenced by cognitive factors or task demands; however, data from patients with anxiety disorders suggest deviations in the BAEP. It has been hypothesized that these differences reflect heightened activation of structures involved in defensive states, such as the amygdala and locus coeruleus, projecting to the inferior colliculus, one of the brainstem generators of wave V of the BAEP. The present study investigated this possibility by testing BAEP during experimentally induced anxiety in healthy volunteers.

METHODS

In this study, BAEP were recorded from healthy normal volunteers under threat of shock, compared with safe conditions.

RESULTS

The first experiment (n = 12) showed that shock anticipation increased the amplitude of wave V. A replication experiment (n = 13) confirmed this finding.

CONCLUSIONS

Although BAEP are highly robust with respect to attentional manipulations, they are affected by transient activation of the fear system due to threat of shock. This finding indicates that some of the electrophysiological brainstem abnormalities observed in anxiety disorders can be replicated in healthy control subjects by inducing a transient state of anxiety.

Transdermal nicotine administration enhances automatic auditory processing reflected by mismatch negativity

Mismatch negativity (MMN) is a component of event-related potentials (ERPs) with a wide-ranging applicability to the investigation of neuronal substrates of information processing in normal and psychopathological states. Nicotine has been shown to be implicated in the pathophysiology of psychiatric disorders as schizophrenia or Alzheimer's disease, and has also been proposed as a self-administered drug in schizophrenia. The goal of the present study is to elucidate the effect of nicotine on the auditory automatic processing reflected by MMN. Nicotine was administered transdermally under controlled dosage. Ten healthy volunteers attended the laboratory for one baseline session and two test sessions. The test sessions involved administration of a placebo patch and a nicotine skin patch, which were counter-balanced. The ERPs were recorded passively during an auditory oddball paradigm. Nicotine administration shortened the MMN latencies, and these effects were independent of the earlier ERP components, N100 and P200. In conclusion, nicotine enhances preattentive and automatic processing such as MMN system and these effects appear to be quite specific and independent of earlier cognitive stages than preattentive mismatch processing. The shortened MMN latency may be interpreted as a reduction of the amount of time required to complete a neuronal mismatch process through the ascending auditory pathway.

Behavioral Inhibition: Linking Biology and Behavior within a Developmental Framework

Behavioral inhibition refers to a temperament or style of reacting that some infants and young children exhibit when confronted with novel situations or unfamiliar adults or peers. Research on behavioral inhibition has examined the link between this set of behaviors to the neural systems involved in the experience and expression of fear. There are strong parallels between the physiology of behaviorally inhibited children and the activation of physiological systems associated with conditioned and unconditioned fear. Research has examined which caregiving behaviors support the frequency of behavioral inhibition across development, and work on the interface of cognitive processes and behavioral inhibition reveal both how certain cognitive processes moderate behavioral inhibition and how this temperament affects the development of cognition. This research has taken place within a context of the possibility that stable behavioral inhibition may be a risk factor for psychopathology, particularly anxiety disorders in older children. The current chapter reviews these areas of research and provides an integrative account of the broad impact of behavioral inhibition research.

Epigenetic Inheritance and the Intergenerational Transfer of Experience

Currently, behavioral development is thought to result from the interplay among genetic inheritance, congenital characteristics, cultural contexts, and parental practices as they directly impact the individual. Evolutionary ecology points to another contributor, epigenetic inheritance, the transmission to offspring of parental phenotypic responses to environmental challenges-even when the young do not experience the challenges themselves. Genetic inheritance is not altered, gene expression is. Organismic pathways for such transmission exist. Maternal stress during the latter half of a daughter's gestation may affect not only the daughter's but also grand-offspring's physical growth. The author argues that temperamental variation may be influenced in the same way. Implications for theory and research design are presented along with testable predictions.

Biology, context, and developmental inquiry

This chapter summarizes some of the conceptual changes in developmental research over the last half-century. These advances include an acknowledgment of the role of maturation; also recognized have been the need for positing distinct psychological structures, the influence of temperament, the malleability of the infant, the role of the local context, and the dynamic nature of the categories describing human psychological types.

Mismatch negativity in socially withdrawn children

BACKGROUND

Individual differences in auditory processing have been associated with social withdrawal, introversion, and other forms of dysfunction in social engagement. The goal of this study was to investigate the characteristics of an electrophysiologic response that is seen to index early cortical auditory processing (mismatch negativity, MMN) among socially withdrawn and more sociable control children.

METHODS

Auditory event-related potentials to standard and deviant tone stimuli were computed for 23 socially withdrawn children and 22 control subjects. We calculated MMN difference waveforms for frontal, central, and parietal electrode sites.

RESULTS

Socially withdrawn children had smaller MMN amplitude and longer MMN latencies compared with more sociable control children.

CONCLUSION

The findings point to the involvement of individual differences in early cortical auditory processing in childhood social withdrawal. Reduced MMN amplitude and delayed latency may index a component of social withdrawal seen in socially withdrawn children and in depressed and schizophrenic patients. The existence of a secondary MMN generator in the frontal cortex may provide a link between the hypothesized frontal lobe involvement in childhood social withdrawal, schizophrenia, and depression and the MMN reductions seen in these conditions.

Introversion and individual differences in middle ear acoustic reflex function

A growing body of psychophysiological evidence points to the possibility that individual differences in early auditory processing may contribute to social withdrawal and introverted tendencies. The present study assessed the response characteristics of the acoustic reflex arc of introverted-withdrawn and extraverted-sociable individuals. Introverts displayed a greater incidence of abnormal middle ear acoustic reflexes and lower acoustic reflex amplitudes than extraverts. These findings were strongest for stimuli presented at a frequency of 2000 Hz. Results are discussed in light of the controversy concerning the anatomic loci (peripheral vs. central neuronal activity) of the individual differences between introverts and extraverts in early auditory processing.

Temperamental contributions to the affect family of anxiety

The discovery of pharmacologic interventions that mute the intensity of anxiety and guilt in some individuals has been a benevolent gift to those who suffer from these disabling states. Although some commentators have wondered about the social consequences of large numbers of asymptomatic persons taking these drugs, few have questioned the advantages for the smaller group of anguished patients. It is likely, however, that, during the next century, scientists will discover a drug that eliminates the feeling components of guilt and remorse while leaving intact the semantic knowledge that certain acts are ethically improper. An individual who took this drug regularly would continue to know that deceiving a friend, lying to a client, and stealing from an employer are morally wrong but would be protected from the uncomfortable feeling of guilt or remorse that accompanies a violation of a personal moral standard. It is reasonable to wonder, therefore, whether our society would be changed in a major way if many citizens were protected from guilt and remorse. Most Western philosophers, especially Kant, made reason the bedrock of conscience. People acted properly, Kant believed, because they knew that the behavior was morally right. All individuals wish to regard the self as virtuous and try to avoid the uncertainty that follows detection of the inconsistency that is created when they behave in ways that are not in accord with their view of the self's desirable attributes. Kant believed that, although the moral emotions restrain asocial acts, they were not necessary for the conduct of a moral life. On the other hand, some philosophers, such as Peirce and Dewey, argued that anticipation of anxiety, shame, and guilt motivate a continued loyalty to one's ethical standards. A person who was certain that he or she was protected from these uncomfortable emotions would find it easier to ignore the moral imperatives acquired during childhood and adolescence. It is not obvious that a drug that blocks remorse also will eliminate the mutual social obligations that make a society habitable; nonetheless, a posture of vigilance that is appropriate for--unlike gorillas--humans can hold representations of envy, anger, and dislike toward people they have never met for a very long time. While we wait for future inquiry to resolve this issue, it is useful to acknowledge that a satisfying analysis of this problem will require a deeper appreciation of the differences between the representations of the biological events that are the foundation of an emotion and the representations that define the semantic networks for the concepts good and bad.