Keith Oatley

Extinction induced drinking in hungry rats.

Rats undergoing extinction of instrumental behaviour previouly rewarded by food in Skinner boxes and consummatory behaviour in the home cage showed increased drinking compared with control animals. Also during extinction the number of bouts of licking increased above the levels observed before extinction of the food acquiring response. Increased drinking in extinction depended on a certain level of food deprivation, and did not occur substantially in only slightly hungry rats. It did occur in rats not allowed water while working for food and thus it could not be attributed principally to perseveration of drinking behaviour acquired while eating. These phenomena appear to be displacement activities by hungry rats whose expectations of receiving food are not fulfilled. The explanation of the behaviour observed as frustration induced displacement activity may be applicable both to starvation polydipsia and to schedule induced polydipsia.

The effect of hunger on water intake in rats

Although reciprocal inhibition between eating and drinking has been postulated, the commonly observed reduction of water intake by hungry rats may not be due to any direct inhibitory mechanism. In one experiment rats deprived of food for 24 hr. and then injected with 2 ml. of NaCl drank the same as rats that had received food ad lib. In the second experiment a stomach load of 10 ml. of water 3 hr. before the salt injection was designed to abolish any water deficit that might have occurred during food deprivation had there been inhibition of drinking by hunger. Here again rats deprived of food did not drink less than undeprived animals. In fact the hungry rats drank slightly but significantly more. This phenomenon may be related to the observation confirmed here that during food deprivation rats excrete about twice as much rather dilute urine as during ad lib food intake. This seems to indicate that though in general food deprived rats drink less than normal they actually drink more than they need. Schedule induced polydipsia also occurs during food deprivation and this too makes it unlikely that water-intake is actually inhibited during hunger.

The passage of food through the gut of rats and its uptake of fluid

Stomachs and small intestines were examined and weighed up to 6 h after rats had been allowed to eat for 30 min without water available. A meal of commercial rat food left the stomach with a time constant of about 4 h. Each gram of food eaten attracted approximately 1 ml of additional fluid into the gut. The time course of this fluid movement and of electrolyte absorption is such that much of the drinking associated with meals in conditions of ad lib intake of food and water seems to be in anticipation of changes in the body fluids, rather than in response to them.

Feeding and arteriovenous differences of blood glucose in rats after injection with 2-deoxy-D-glucose and after food deprivation

Abstract Normal and adrenally demedullated rats injected with approximately 200 mg per kg of 2-deoxy-D-glucose (2-DG) ate just over 1 g more food than controls in 3-hr eating tests. This eating response was unaffected by delaying access to food by 30 min. Injections of 6-deoxy-D-glucose also increased eating, but less than 2-DG. Rats deprived of food for 24 hr ate about twice as much food as those injected with 2-DG. Drinking was increased following 2-DG in some but not all the experiments. Ether anaesthesia at the time of the injection depressed subsequent drinking but not eating. Arteriovenous differences of blood glucose (measured between carotid artery and jugular vein, and between carotid artery and femoral vein) were decreased after 24 hr deprivation of food, but slightly increased after injections of 2-DG. 2-DG stimulates eating without decreasing the rate of uptake of glucose from the blood.

Air drinking and the measurement of thirst

Summary 1. Rats drinking air after deprivation of water show a similar pattern of performance to rats drinking water. Like the number of licks taken at a water spout in 1 hr, the number of air licks for both high and low pressure air streams was a nearly linear function of the length of deprivation. 2. Histograms of intervals between licks are also similar for water and air. Variation of motivation or incentive did not substantially affect the pattern of licking. Only rats drinking water in response to concentrated NaCl injections showed any change from normal in their local rate of licking. 3. Rats took more licks to air than to water, and the cumulative licking curves showed that the rate of drinking air did not diminish nearly as much as it did for water. This would be expected if air has its mildly satiating effect by providing decaying short-term feedback. 4. Part of the satiating effect of air may be due to simple gut distension. Rats swallowed a substantial quantity of air which was found in their stomachs and intestines after air drinking. There was no evidence that distension by air was aversive. 5. Air drinking, though it does not remove all feedback from drinking, provides a useful consummatory measure of thirst which is free of the absorptive effects of drinking water.

Inhibition of ad Libitum Feeding in Rats by Salt Injections and Water Deprivation

Inhibition of ad libitum feeding in rats was induced by hypertonic NaCl injections. Though osmotic loads of sufficient size were capable of abolishing feeding completely for a time, the effect was not as large as had been predicted from a hypothesis of strictly linear subtractive inhibition. Feeding at a low level of hunger seems to be somewhat less affected by osmotic inhibition than feeding on a deprivation schedule. Inhibition of feeding was also produced by deprivation of water, and both the inhibition of food intake during deprivation, and the disinhibition by subsequent drinking indicated that the amount of inhibition of food intake is a non-linear (accelerating) function of water deficit. A model of the process indicating that the thirst signal undergoes a non-linear transformation before being subtracted from the signal corresponding to food demand is proposed.

Judging the order of visual stimuli.

Psychometric functions obtained for judgements of the order of two long duration light flashes were about half as steep as those previously obtained for short flashes. The range from 50 to 75 per cent correct judgements corresponded to interstimulus intervals from 36 to 98 msec. in the 6 subjects tested. Stimuli ½ degree above and below the fixation point produced slightly more accurate judgements than pairs of stimuli 2 degrees above and below this point. The shape of the curves did not conform to a normal ogive of the kind normally expected in threshold determinations. These data may be explicable in terms of a visual sampling mechanism capable of being triggered by incoming stimuli.

Drinking in response to salt injections at different times of day

Drinking tests were carried out on rats at four times of day after NaCl injections of six concentrations. Contrary to what would be expected if a diurnal influence directly modulates the brain mechanisms cantrolling drinking, there was no potentiation or inhibition of drinking at any of the times when tests were made.

Experimental method and psychodynamic theory: discussion paper.

Introduction We live in a world of ambiguities, and in such a world the purpose of experiment is to allow appropriate interpretations of what is observed. Where there-may be underlying regularities, the experiment makes it easier to know which hypotheses about those regularities can sensibly be entertained and which need to be changed because they are mistaken. Control conditions in experiments function, simply, to control the range ofpossible interpretations of phenomena. It will be argued here that the idea of the experiment is of fundamental importance for understanding and advancing psychodynamic theory. It is important in two ways: first in evaluating the outcomes of therapy, and secondly as a description of the nature of psychodynamic therapy. Therapy is an activity in which the patient is both experimenter and subject of a kind of experiment.

Self-Help Groups for Agoraphobics: Their Role in Coping with Anxiety and Depression

“A group is the beginning of everything,” wrote Peter Uspenskii, “one man can do nothing, attain nothing… a group of people can do what one man can never do” (Uspenskii, 1950).