Blink startle modulation during anticipation of pleasant and unpleasant stimuli

The present research investigated blink startle modulation during the anticipation of pleasant, unpleasant, or neutral pictures. In Experiment 1 (N = 18), participants were presented with three different tone-picture pairings. Tones differed in pitch and were followed by pleasant, neutral or unpleasant pictures. Acoustic blink reflexes were elicited during some tones and during stimulus free intervals. Blink facilitation during tones that preceded pleasant and unpleasant pictures was larger than during the tone that preceded neutral pictures. Experiment 2 (N = 10) assessed whether this difference was due to a difference in the presentation frequency of the three conditions. No difference in blink facilitation between the conditions was found when pictures of flowers and mushrooms replaced the pleasant and unpleasant pictures, indicating that picture content was instrumental in causing the differential blink facilitation in Experiment 1. The results from Experiment 1 seem to indicate that startle modulation during the anticipation of pictorial material reflects the interest in or the arousal associated with the pictures rather than picture valence.

Rebreathing potential of infant mattresses and bedcovers

Objective : To establish the CO2 dispersion and retention properties of some mattresses and bed coverings commercially available in Australia. Methods : Five mattresses were studied in (i) an in vivo model in which an infant's head was covered by a headbox, rebreathing was allowed to occur, and the final steady state CO2 concentration was measured; and (ii) an in vitro model in which 5% CO2 in a headbox was allowed to disperse, and the time taken for the concentration to reach 1% was measured. Five types of bedcover were studied in (i) an in vivo model in which an infant's head was covered by a bedcover and the final steady state CO2 concentration was measured; and (ii) an in vitro model in which 5% CO2 under a bedcover was allowed to disperse, and the time taken for the concentration to reach 1% was measured. Results : The steady state CO2 concentrations ranged from 0.6% to 3.0% for the mattresses (P < 0.05). The time for CO2 to disperse ranged from 5.5 min to 30.4 min (P < 0.05). Steady state CO2 concentrations ranged from 2.5% to 3.6% for the bedcoverings (P > 0.05). The time for CO2 to disperse ranged from 5.4 min to 7.7 min (P > 0.05). Conclusions : Some commercial cot mattresses and bedcoverings allow high concentrations of CO2 to accumulate in rebreathing environments. Some mattress types studied were more diffusive to CO2 , whereas there was no difference between the bedcovers studied. This may have implications for vulnerable infants at risk of sudden infant death syndrome.

Barriers to effective cancer pain management: A survey of hospitalized cancer patients in Australia

The purpose of this study was to examine attitudinal barriers to effective pain management in a consecutively recruited cohort of 114 cancer patients from four Australian hospitals. When surveyed, 48% of this sample reported experiencing pain within the previous 24 hours. Of these, 56% reported this pain to be distressing, horrible or excruciating, with large proportions indicating that this pain had affected their movement, sleep and emotional well-being. Three factors were identified as potentially impacting on patients responses to pain-poor levels of patient knowledge about pain, low perceived control over pain, and a deficit in communication about pain. A trend for older patients to experience more severe pain was also identified. These older patients reported being more willing to tolerate pain and perceive less control over their pain. Suggestions are made for developing patient education programs and farther research using concepts drawn from broader social and behavioral models. J Pain Symptom Manage 2002:23:393-405. (C) U.S. Cancer Pain Relief Committee, 2002.

Contribution of cholinergic systems to state-dependent modulation of respiratory control

Respiration is altered during different stages of the sleep-wake cycle. We review the contribution of cholinergic systems to this alteration, with particular reference to the role of muscarinic acetylcholine receptors (MAchRs) during rapid eye movement (REM) sleep. Available evidence demonstrates that MAchRs have potent excitatory effects on medullary respiratory neurones and respiratory motoneurones, and are likely to contribute to changes in central chemosensitive drive to the respiratory control system. These effects are likely to be most prominent during REM sleep, when cholinergic brainstem neurones show peak activity levels. It is possible that MAchR dysfunction is involved in sleep-disordered breathing, Such as obstructive sleep apnea. (C) 2002 Elsevier Science B.V. All rights reserved.

The distribution and morphological characteristics of catecholaminergic cells in the brain of monotremes as revealed by tyrosine hydroxylase immunohistochemistry

The present study describes the distribution and cellular morphology of catecholaminergic neurons in the CNS of two species of monotreme, the platypus (Ornithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). Tyrosine hydroxylase immunohistochemistry was used to visualize these neurons. The standard A1-A17, C1-C3 nomenclature was used for expediency, but the neuroanatomical names of the various nuclei have also been given. Monotremes exhibit catecholaminergic neurons in the diencephalon (All, A12, A13, A14, A15), midbrain (A8, A9, A10), rostral rhombencephalon (A5, A6, A7), and medulla (A1, A2, C1, C2). The subdivisions of these neurons are in general agreement with those of other mammals, and indeed other amniotes. Apart from minor differences, those being a lack of A4, A3, and C3 groups, the catecholaminergic system of monotremes is very similar to that of other mammals. Catecholaminergic neurons outside these nuclei, such as those reported for other mammals, were not numerous with occasional cells observed in the striatum. It seems unlikely that differences in the sleep phenomenology of monotremes, as compared to other mammals, can be explained by these differences. The similarity of this system across mammalian and amniote species underlines the evolutionary conservatism of the catecholaminergic system. Copyright (C) 2002 S. Karger AG, Basel.

The distribution and morphological characteristics of serotonergic cells in the brain of monotremes

The distribution and cellular morphology of serotonergic neurons in the brain of two species of monotremes are described. Three clusters of serotonergic neurons were found: a hypothalamic cluster, a cluster in the rostral brainstem and a cluster in the caudal brainstem. Those in the hypothalamus consisted of two groups, the periventricular hypothalamic organ and the infundibular recess, that were intimately associated with the ependymal wall of the third ventricle. Within the rostral brainstem cluster, three distinct divisions were found: the dorsal raphe nucleus (with four subdivisions), the median raphe nucleus and the cells of the supralemniscal region. The dorsal raphe was within and adjacent to the periaqueductal gray matter, the median raphe was associated with the midline ventral to the dorsal raphe, and the cells of the supralemniscal region were in the tegmentum lateral to the median raphe and ventral to the dorsal raphe. The caudal cluster consisted of three divisions: the raphe obscurus nucleus, the raphe pallidus nucleus and the raphe magnus nucleus. The raphe obscurus nucleus was associated with the dorsal midline at the caudal-most part of the medulla oblongata. The raphe pallidus nucleus was found at the ventral midline of the medulla around the inferior olive. Raphe magnus was associated with the midline of the medulla and was found rostral to both the raphe obscurus and raphe pallidus. The results of our study are compared in an evolutionary context with those reported for other mammals and reptiles. Copyright (C) 2002 S. Karger AG, Basel.

The distribution and morphological characteristics of cholinergic cells in the brain of monotremes as revealed by ChAT immunohistochemistry

The present study employs choline acetyltransferase (ChAT) immunohistochemistry to identify the cholinergic neuronal population in the central nervous system of the monotremes. Two of the three extant species of monotreme were studied: the platypus (Omithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus). The distribution of cholinergic cells in the brain of these two species was virtually identical. Distinct groups of cholinergic cells were observed in the striatum, basal forebrain, habenula, pontomesencephalon, cranial nerve motor nuclei, and spinal cord. In contrast to other tetrapods studied with this technique, we failed to find evidence for cholinergic cells in the hypothalamus, the parabigeminal nucleus (or nucleus isthmus), or the cerebral cortex. The lack of hypothalamic cholinergic neurons creates a hiatus in the continuous antero-posterior aggregation of cholinergic neurons seen in other tetrapods. This hiatus might be functionally related to the phenomenology of monotreme sleep and to the ontogeny of sleep in mammals, as juvenile placental mammals exhibit a similar combination of sleep elements to that found in adult monotremes. Copyright (C) 2002 S. Karger AG, Basel.

Vicarious dissonance: Attitude change from the inconsistency of others

Three studies support the vicarious dissonance hypothesis that individuals change their attitudes when witnessing members of important groups engage in inconsistent behavior. Study 1, in which participants observed an actor in an induced-compliance paradigm, documented that students who identified with their college supported an issue more after hearing an ingroup member make a counterattitudinal speech in favor of that issue. In Study 2, vicarious dissonance occurred even when participants did not hear a speech, and attitude change was highest when the speaker was known to disagree with the issue. Study 3 showed that speaker choice and aversive consequences moderated vicarious dissonance, and demonstrated that vicarious discomfort-the discomfort observers imagine feeling if in an actor's place-was attenuated after participants expressed their revised attitudes.