Periodicity and memory in mice

Abstract

Mice given ECS after training on an inhibitory avoidance task showed greater retrograde amnesia when training and treatments were given near the crest of the daily activity rhythm as measured by rectal temperature.Evidence has accumulated in recent years that fluctuations in activity levels along the 24-h continuum are characteristic of many organs and organ systems (Halberg, 1960;Halberg, Albrecht, & Bittner, 1959;Harner, 1961).Several studies have indicated that a number of biologic variables may be related to learning and memory and to the response to amnesic agents such as electroconvulsive shock (ECS). An interaction between strain and phase of the activity cycle has been shown to influence maze learning performance in two strains of inbred mice (Hostetter, 1966). Thresholds to electroshock convulsions in rats were observed to be significantly lower at night than in the early afternoon (Woolley & Timiras, 1962). Age (Tattan, 1957) and strain (Hudspeth, McGaugh, & Thomson, 1964; OliveriO, McGaugh, & Bovet, in preparation;Thompson & Dean, 1955) have been shown to influence the degree of amnesia produced by electroconvulsive shock.The preliminary experiments reported here were designed to investigate: (1) whether learning and memory in an inhibitory avoidance task in routine-standardized animals will vary with the rectal temperature rhythm, and (2) whether the amnesic effects of electroconvulsive shock following avoidance training will vary as a function of this rhythm. SubjectsSwiss Webster male mice approximately 60 days of age were used as Ss. They were housed four animals per cage with ad lib food and water. Cages were kept on open shelves in a small quiet room lighted by a fluorescent ceiling fixture from 4 a.m. to 4 p.m. and completely dark from 4 p.m. to 4 a.m. Room temperature was maintained at about 22 o C. Animals were taken from the colony room at least eight days prior to the experiments, and kept in this standardization room prior to and during the experimental period. The rectal temperature rhythm was spot checked with a Yellow Springs Telethermometer. In these animals, under these conditions, rectal temperature averaged 34.9±.69 0 C at 1 p.m. and 36.5 ± 1.7 o C at 9 p.m. ApparatusThe apparatus for inhibitory avoidance training was that described by McGaugh & Alpern (1966 GWEN STEPHENS, JAMES L. McGAUGH AND H. P. ALPERN UNIVERSITY OF CALIFORNIA, IRVINEtraining electroshock consisted of a current of apprOximately 8 rnA delivered for .8 sec by way of corneal electrodes. The animal was held in the E's hand during ECS administration. Resuscitation via the nose and mouth by means of a plastic bottle and tube was administered to all animals immediately after the shock.EXPERIMENT 1 Seventy-two animals were divided into SIX groups of 12 animals each. starting at 1 p.m. each animal of the first three groups was given three training trials in immediate succession on the inhibitory avoidance learning task. For each trial the mouse was placed on a small lighted metal platform in front of a hole leading into...

A Diurnal Rhythm of Immunoreactive <i>α</i>-Melanocyte-Stimulating Hormone in Discrete Regions of the Rat Brain

“…Both sleep-waking behavior and at tention processes demonstrate obvious circa dian rhythmic patterns [1,5,23,24], Further more, Sandman et al [23] have shown that a-MSH selectively improves a passive avoid ance response in the dark but not in the light period of the light cycle. These data may in dicate a role for a-MSH in circadian varia tions in behavioral processes.…”

“…Dra matic circadian rhythms of adaptive altera tions in skin color have been observed through out the animal kingdom and was suggested to be due, in part, to diurnal variation in secre tion of a-MSH from the intermediate lobe of the pituitary gland [10]. Recently, extrapigmentary effects of a-MSH were described which include potent central nervous system effects such as increased behavioral arousal, attention and vigilance -adaptive behaviors, which all seem to have circadian components [1,5,23,24], As very little of the a-MSH in the brain is derived from the pituitary, the a-MSH neuronal system of the brain may partic ipate in the manifestation of such diurnal rhythms. In this experiment, therefore, a diur nal variation of a-MSH concentrations in dis crete areas of the brain has been investigated.…”

Developing Standardized Behavioral Tests for Knockout and Mutant Mice

“…Behavior may be influenced by the time of testing during the L:D cycle (Miyamoto et al 1986;Rosenwasser et al 1979;Sandman et al 1971;Stephens et al 1967). For example, Kriegsfeld et al (1999) found that nitric oxide synthase knockout mice had deficits in motor coordination when tested in the dark phase of the L:D cycle but not when tested in the light phase.…”

Vertebrate Behavioral Rhythms

“…In one study, performance efficiency, but not acquisition, was affected by time of day of testing (Ghiselli and Patton, 1976); in another, initial performance was equivalent among groups, but resistance to extinction varied dramatically with time of training (Ternes, 1976). Electroconvulsive shock (ECS) given to mice immediately after training disrupted memory equally well at two times of day, but ECS given 3 min after training disrupted memory only in mice tested during the D phase and not in those tested in L (Stephens, McGaugh, and Alpern, 1967). It is possible that memory consolidation proceeds at different rates at different times of day.…”