The locus coeruleus-noradrenergic system: modulation of behavioral state and state-dependent cognitive processes.

Spontaneous discharge of norepinephrine-containing locus coeruleus (NE-LC) neurons was examined during the sleep-walking cycle (S-WC) in behaving rats. Single unit and multiple unit extracellular recordings yielded a consistent set of characteristic discharge properties. (1) Tonic discharge co-varied with stages of the S-WC, being highest during waking, lower during slow wave sleep, and virtually absent during paradoxical sleep. (2) Discharge anticipated S-WC stages as well as phasic cortical activity, such as spindles, during slow wave sleep. (3) Discharge decreased within active waking during grooming and sweet water consumption. (4) Bursts of impulses accompanied spontaneous or sensory-evoked interruptions of sleep, grooming, consumption, or other such ongoing behavior. (5) These characteristic discharge properties were topographically homogeneous for recordings throughout the NE-LC. (6) Phasic robust activity was synchronized markedly among neurons in multiple unit populations. (7) Field potentials occurred spontaneously in the NE-LC and were synchronized with bursts of unit activity from the same electrodes. (8) Field potentials became dissociated from unit activity during paradoxical sleep, exhibiting their highest rates in the virtual absence of impulses. These results are generally consistent with previous proposals that the NE-LC system is involved in regulating cortical and behavioral arousal. On the basis of the present data and those described in the following report (Aston-Jones, G., and F. E. Bloom (1981) J. Neurosci.1: 887-900), we conclude that these neurons may mediate a specific function within the general arousal framework. In brief, the NE-LC system may globally bias the responsiveness of target neurons and thereby influence overall behavioral orientation.

https://www.jneurosci.org/content/jneuro/1/8/876.full.pdf

Activity of norepinephrine-containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-waking cycle

The author explores the viability of a comparative approach to personality research. A review of the diverse animal-personality literature suggests that (a) most research uses trait constructs, focuses on variation within (vs. across) species, and uses either behavioral codings or trait ratings; (b) ratings are generally reliable and show some validity (7 parameters that could influence reliability and 4 challenges to validation are discussed); and (c) some dimensions emerge across species, but summaries are hindered by a lack of standard descriptors. Arguments for and against cross-species comparisons are discussed, and research guidelines are suggested. Finally, a research agenda guided by evolutionary and ecological principles is proposed. It is concluded that animal studies provide unique opportunities to examine biological, genetic, and environmental bases of personality and to study personality change, personality-health links, and personality perception.

From mice to men: what can we learn about personality from animal research?

https://www.reed.edu/biology/professors/srenn/pages/teaching/2008_syllabus/2008_readings/1_MorganTromborg2008.pdf

Sources of stress in captivity

The circadian rhythm of body temperature.

Phases and states of sleep in the rat

Influence of environmental temperature on the sleep-wakefulness cycle in the rat.

Handling and Isolation in Three Strains of Rats Affect Open Field, Exploration, Hoarding and Predation

Adult male hooded (Long-Evans) rats (Rattus norvergicus) were used to compare the efficiency of three types of tests (plain open field - OF, open field with a refuge - OD, and complex environment with a refuge - EX), for the evaluation of exploratory behaviour. The results confirmed that OF is a highly aversive situation with the animals showing elevated emotional response (defecation and urination) when compared to situations containing a refuge (OD and EX). Presence of a plain arena (OF and OD) does not elicit high exploratory performance, as shown by the delayed and reduced exit from the refuge in OD when compared to EX. Thus locomotor activity in OF (covered distance, number of rearings) probably reflects more of an escape reaction than a genuine exploratory behaviour. Conversely the presence of a complex environment seems to elicit a high exploratory performance expressed as a quick exit from the refuge, an increased time in the environment (more than 75% of the observation time) and intense locomotor patterns (large covered distances, great number of rearings) but with little emotional display (reduced defecation and urination). The results thus show the importance of considering ethological factors in the choice or development of laboratory tests.

Exploratory Activity of Rats in Three Different Environments

http://www.grupoetco.org.br/arquivos_br/pdf/suckling.pdf

W R Schmidek

Papers

Phases and states of sleep in the rat

Influence of environmental temperature on the sleep-wakefulness cycle in the rat.

Handling and Isolation in Three Strains of Rats Affect Open Field, Exploration, Hoarding and Predation

Exploratory Activity of Rats in Three Different Environments

Suckling and allosuckling in river buffalo calves and its relation with weight gain