Arousal Pathways Research Articles

The interactive relations between trait hostility, pain, and aggressive thoughts

A recent model of affective aggression [Anderson et al., 1996] proposes that individual differences and situational factors can affect aggressive behavior through cognitive, affective, and arousal pathways. An experiment tested the relations of trait hostility and physical pain to aggressive thoughts (the cognitive path) and state hostility (the affective path). The experiment found an interaction between pain and trait hostility on aggressive thoughts. Trait hostile participants who experienced pain rated ambiguous words (e.g., alley) as more similar to aggressive words (e.g., hit) than did the other groups. State hostility was positively related to trait hostility and was increased by the experience of pain. These results demonstrate the heuristic utility of the Anderson et al. Model. Aggr. Behav. 24:161–171, 1998. © 1998 Wiley-Liss, Inc.

Projections of Giant Fibers, a Class of Reticular Interneurons, in the Brain of the Silver Hatchetfish

Giant fibers are large reticular interneurons that mediate excitatory input from the Mauthner cells to pectoral-fin motoneurons. The present study revealed extensive giant-fiber projections to central targets other than the pectoral-fin motoneurons. Physiologically identified giant fibers were filled intracellularly with Lucifer Yellow. The presence of numerous dendrites suggests that there may be significant integration of non-Mauthner inputs in the giant-fiber cell body. The axon decussates and then bifurcates to form a descending process, that innervates pectoral-fin motoneurons, and an ascending process with collaterals that terminate in the rostral trigeminal, rostral facial and, in some cases, oculomotor and trochlear motor nuclei. The projections are consistent with a role for the giant fibers as mediators of all the cranial components of the Mauthner-initiated startle response. There are also extensive projections to cells near the Mauthner cell and to the medial reticular formation. The latter projections may participate in longer-latency components of the Mauthner-initiated startle response, or they may constitute part of a general arousal pathway. The morphology of giant fibers suggests that they are homologous to cranial relay neurons in the goldfish and T reticular interneurons in zebrafish larvae. Non-Mauthner inputs to giant fibers may participate in non-Mauthner startle responses and contribute to the variability of Mauthner-mediated startle responses.

Serious-mindedness and the effect of self-induced respiratory changes upon parietal EEG.

The role of serious-mindedness (so-called telic dominance) in regulation of parietal cortex EEG was investigated. Ten telic (serious-minded) and 10 paratelic (playful state-dominant) individuals were selected on the basis of their responses to the Telic Dominance Scale. They all performed instructed breathholding (hypopnea) and excessive breathing (hyperpnea) in counterbalanced order. The paratelic individuals yielded relatively high scores of integral EEG power; theta power was markedly increased in the left hemisphere during hyperpnea, and reduced in the right hemisphere during hypopnea. Both hyperpnea and hypopnea were reported to be more aversive to the paratelic than to the telic subjects, but no group difference in respiratory activity was found. The electrocortical and hedonic tone differences between the groups are discussed in relation to the distinction between the prefrontal (dopamine) activation pathway and frontoparietal (noradrenalin) arousal pathway, as well as in relation to changes in cortical blood flow and proprioceptive feedback.

Arousal changes in the locust optomotor system

The activity of the optomotor interneurons in the locust optic lobe varies with arousal states. Two behaviourally different arousal situations can be readily reproduced in the locust, a spontaneous and an evoked arousal change. These produce different neuronal correlates in the optomotor interneurons, suggesting the presence of different arousal pathways possibly acting at different sites in the motion detection chain. Furthermore, an additional arousal effect can be demonstrated at the motoneurons showing that a reflex system is sensitive to arousal modulation at several levels.

Reserpine action on the central nervous system of the cat.

Recordings of spontaneous activity and induced arousal in cats with permanently implanted electrodes have failed to demonstrate any effect by reserpine on arousal pathways. Recordings of spontaneous and induced activity of the rhinencephalon have indicated that this region is not involved in any specific fashion by reserpine. Evidence is presented that the miotic effect of reserpine requires the integrity of most of diencephalon but that the effect may be produced with the central sympathetic connections interrupted.