Central blockade of (methyl-)atropine on carbachol drinking: A dose-response study

Administration of carbachol in the tractus diagonalis in rats elicited drinking and no eating. Norepinephrine administered in the same place did not induce drinking or eating. The specific drinking response induced by stimulation with 7.2 nmol (= 1.3 μg) of carbachol was gradually inhibited by preceding injections of graded doses of atropine and methylatropine at the same site. A 90% inhibiting action of atropine and methylatropine was possible with a 3–10 times lower dose (0.18 μg) than used in earlier studies. Significant differences between the inhibition by atropine and methylatropine could not be demonstrated. A possible difference in inhibition at the lowest dose of atropine and methylatropine used (= 0.04 μg) was discussed

The reinforcing effect of electrical stimulation of the tongue in thirsty rats : brief communication

Thirsty rats repeatedly closed the electric circuit of a drinkometer with their tongue in the absence of water. The hypothesis that electrical stimulation of the tongue has reinforcing properties was tested. The results indicate that persistent licking by a thirsty rat is dependent on a current as low as 1 μA

The role of the tractus diagonalis in drinking behaviour induced by central chemical stimulation, water deprivation and salt injection

The role of the tractus diagonalis in drinking behaviour induced by central chemical stimulation, 23-hr water deprivation and injection of a hypertonic sodium chloride solution was investigated by means of central and peripheral administration of atropine and methylatropine. The effect of the same doses of centrally and peripherally administered anticholinergics was greater on carbachol-induced drinking than on deprivation-induced drinking. Salt-induced drinking was only influenced by peripheral administration of the anticholinergics. The results indicate the presence of a central cholinergic and a peripheral cholinergic active mechanism in carbachol-induced drinking; a central cholinergic, a peripheral cholinergie and a non-cholinergic mechanism in deprivation-induced drinking; and a central cholinergic, a peripheral cholinergic and a non-cholinergic mechanism in salt-induced drinking. It is concluded that a cholinergic system cannot be the system that has an overall control over water intake behaviour. The results obtained make it questionable whether the tractus diagonalis has a specific function in the series of events that lead to water intake after water deprivation or a salt injection

The Ro 15-1788 cue: Evidence for benzodiazepine agonist and inverse agonist properties

Rats discriminating Ro 15–1788 (10 mg/kg, i.p.) from vehicle completely generalized this cue to typical benzodizepines, and partially generalized it to barbiturates, pentylenetetrazol, CGS 8216, β-CCM and PK 8165. CL 218 872, Ro 5–4864, phenytoine, progabide, propranolol, yohimbine and various CNS stimulants predominantly induced vehicle-appropriate responding. Chlordiazepoxide, pentobarbital, CL 218 872, PK 8165, pentylenetetrazol, CGS 8216 and β-CCM failed to block the Ro 15–1788 cue. Generalization to both anxiolytics/anticonvulsants and anxiogenics/(pro) convulsants suggests that Ro 15–1788 has benzodiazepine agonist and inverse agonist properties

Removal of the ocular artifact from the EEG: a comparison of time and frequency domain methods with simulated and real data

Constructed 2 data sets from simulated data, in which the transfer from electrooculogram (EOG) to EEG was either frequency-independent (constant gain) or frequency-dependent. Three different correction methods were applied: simple regression analysis (RA) in the time domain, a multiple-lag RA in the time domain, and an RA in the frequency domain. For Data Set 1, the 3 methods constructed the original EEG equally well. With Data Set 2, reconstruction of the original EEG was achieved reasonably well with the frequency domain method and the time domain multiple-lag method, but not with simple time domain regression. These 3 correction procedures were also applied to real data, consisting of concomitantly recorded EEG and high-variance EOG series. There were no differences in outcome of the 3 methods

Eye-movements in a two-dimensional plane: A method for calibration and analysis using the vertical and horizontal EOG

A method for calibration, orthogonalization and standardization of eye movements is described. The method is based on linear transformation of the horizontal and vertical EOG. With this method it is possible to measure the locus of eye fixation on a TV screen and its associated fixation time. Because of the used time constant (TC) of 36 sec, subjects must look at the centre of the TV screen or at random places on the screen during the interstimulus intervals (ISIs). For the EOG registration pre-amplifiers with a long TC were used to cut off slow changes in polarization caused by the electrode-electrolyte combination. In the calibration procedure only four orthogonal stimulus points were used. In an experiment to evaluate this method, subjects had to fixate letters on a TV screen in 12 different pre-determined positions. The distance between the measured locus of fixation and the coordinates of the stimulus was measured. The mean horizontal errors ranged from 1.4–2.2 degrees of arc and the mean vertical errors from 2.4–3.8 degrees of arc across subjects. It was concluded that accuracy was within acceptable limits, despite the fact that eye movement behaviour during the ISI was free. It was shown that the method is insensitive to non-orthogonality of the vertical and horizontal EOG. Calibration and transformation can be done by any real time computer system. The method is suitable for measuring, e.g. the visual orienting reaction (VOR), and it can also be applied in event related potential (ERP) studies where ocular fixation is use

Norepinephrine uptake by hypothalamic tissue from the rat related to feeding

Norepinephrine (NE) uptake by rat hypothalamus in vitro was studied in relation to food intake. Significant daily variations in NE uptake were observed in caudal hypothalamus from freely feeding rats. A maximal elevation occurred at the beginning of the night when food intake is also increasing to a maximum. NE uptake by caudal hypothalamus from relatively hungry rats previously adjusted to restricted feeding during the daytime was enhanced in afternoon and evening when compared with uptake by tissue from ad lib feeding animals. Determination of NE uptake by caudal hypothalamus from freely feeding individual rats and registration of individual meals taken by these rats revealed a relation between hypothalamic neuronal activity and the feeding pattern of the rat. A positive correlation was observed between NE uptake in vitro and feeding rate during a 2- to 4-hr interval. It also appeared that NE uptake by caudal hypothalamus is dependent on the time elapsed after the last meal. The data were evaluated in view of physiological studies concerning the onset of feeding and the hypothesis of hypothalamic adrenergic control of food intake