摘要：

1. (1) The present paper is concerned with the behavioural and pharmacological data relating to the dorsal ascending noradrenergic bundle (DB), and thus supplements Amaral and Sinnamon's 1977 review of the neurobiology of the locus coeruleus (LC). For completeness, discussion of the neuroanatomy and neurophysiology of the DB has also been included. 2. (2) Neuroanatomy: The DB contains efferents from the LC which have been reported to project, largely ipsilaterally, to the neocortex (frontal, sensorimotor, cingulate, pyriform), rhinecephalon (hippocampus, septum, amygdala, olfactory bulb) and various subcortical areas (thalamus, hypothalamus, colliculi, geniculate bodies and probably the habenula). It appears that not all LC cells project to all these areas. Cells in some parts of LC may project specifically to particular areas. 3. (3) Neurophysiology: In such areas as have been investigated, activation of the DB results in inhibition of the spontaneous activity of single cells by the release of noradrenaline. In the cortex, the released NA may act on some neurones by a process of extra-synaptic diffusion, but this is less likely to be the case in the hippocampus. Despite the inhibition of spontaneous activity, activation of the DB can produce increased rather than decreased responses to subsequent activation of other inputs to the same cells. Thus the main effect of DB input does not appear to be a reduction in the general excitability of target cells, but may be, e.g., a reduction in noise level. The DB appears to provide some type of frequency-specific modulatory influence with respect to hippocampal theta rhythm, but this does not involve obvious changes in the spontaneous occurrence or frequency of the rhythm, and its exact nature remains to be clarified. 4. (4) Physiological functions: The possible involvement of the DB in a number of physiological processes (sensory transmission, visual plasticity, sleep, sexual behaviour, homeostasis) was considered, but cannot be resolved at the present time because few experiments in these areas have employed neurotoxic lesions of the DB alone. There is, however, good evidence for interaction between the DB and the pituitary-adrenal axis. In many cases combination of DB lesion and adrenalectomy impaired avoidance responses which the individual lesions did not affect to any great extent. 5. (5) Pharmacology: Dopaminergic, cholinergic, opiate, intoxicating, convulsant, minor tranquilizing and antidepressant drugs were considered. As might be expected, the DB is not clearly involved with the entire behavioural profile of any of these groups, nor, surprisingly, does it have a uniform influence with respect to similar responses induced by different classes of drug. Thus, the nature of the interaction of DB lesions with drug-induced changes depends on the class of drug for catalepsy, taste aversion, locomotor stimulation and self administration. However, DB lesions potentiate seizures whatever the inducing agent. The clearest involvement of the dorsal bundle is with the behavioural effects of the minor tranquillizers; many of these effects are reproduced by DB lesions, the main exceptions being paradigms involving noxious stimuli. 6. (6) Behavioral functions: Self stimulation and the acquisition of a number of learned responses survive neurotoxic lesion of the DB. Changes are obtained in extinction of almost all simple appetitively- and aversively-reinforced responses, in some reactions to novelty (spontaneous alternation, response to stimulus change, rearing, distraction of licking by a tone), and in some reactions to complex tasks (successive brightness discrimination, spatial alternation, fixed ratio, variable interval, partial reinforcement extinction effect with small numbers of trials) but not others (acquisition of fixed interval, variable ratio or differential reinforcement of low rates schedules, extinction of Sidman avoidance, partial reinforcement extinction effect with large numbers of trials). While forebrain noradrenaline systems may be involved in fear and avoidance res

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