Entropy factor for randomness quantification in neuronal data.

A novel measure of neural spike train randomness, an entropy factor, is proposed. It is based on the Shannon entropy of the number of spikes in a time window and can be seen as an analogy to the Fano factor. Theoretical properties of the new measure are studied for equilibrium renewal processes and further illustrated on gamma and inverse Gaussian probability distributions of interspike intervals. Finally, the entropy factor is evaluated from the experimental records of spontaneous activity in macaque primary visual cortex and compared to its theoretical behavior deduced for the renewal process models. Both theoretical and experimental results show substantial differences between the Fano and entropy factors. Rather paradoxically, an increase in the variability of spike count is often accompanied by an increase of its predictability, as evidenced by the entropy factor.

Randomness of spontaneous activity and information transfer in neurons.

The analysis of information coding in neurons requires methods that measure different properties of neuronal signals. In this paper we review the recently proposed measure of randomness and compare it to the coefficient of variation, which is the frequently employed measure of variability of spiking neuronal activity. We focus on the problem of the spontaneous activity of neurons, and we hypothesize that under defined conditions, spontaneous activity is more random than evoked activity. This hypothesis is supported by contrasting variability and randomness obtained from experimental recordings of olfactory receptor neurons in rats.

Effect of rooibos tea (Aspalathus linearis) on Japanese quail growth, egg production and plasma metabolites.

1. Birds have been proposed as a suitable model for studies on ageing because of their long life in comparison with similar-sized mammals. However, some weak fliers, such as Galliformes, are the exception to this rule. The aim of the present study was to determine the effects of the treatment with rooibos tea (Aspalathus linearis), a natural source of flavonoid antioxidants and compounds with phyto-oestrogenic activity, on postnatal development and egg production of aged Japanese quail (Coturnix coturnix japonica). 2. Substitution of drinking water with traditional rooibos tea or diet supplementation with ground rooibos tea affected body weight of Japanese quail up to 100 d of age. The body weight of males drinking rooibos tea or eating rooibos-supplemented food decreased significantly. There was a trend toward increased body weight of tea drinking females and a significant increase in the body weight of hens fed the rooibos-supplemented diet. Although rooibos treatment did not significantly increase egg production in young hens, the decrease in egg production of rooibos-treated aged hens (360 d of age) was significantly reduced, regardless of the egg production levels (high - 80%; low - 20%) before the treatment. 3. The results suggest that treatment with rooibos tea positively affected body weight and egg production in quail hens and prolonged the productive period of aged animals. Further studies would be needed to address the question whether these effects are due to the antioxidant or phyto-oestrogenic activities of rooibos.

Circadian variation in heart rate, blood pressure, body temperature and EEG of immature broiler breeder chickens in restricted-fed and ad libitum-fed states.

1. Heart rate, intra-aortic blood pressure, deep body temperature and telencephalic EEG were monitored by radiotelemetry in 6 freely moving immature broiler breeders (three in each of two years), during routine food restriction and then ad libitum feeding, over two 24-h periods in each feeding state.2. Heart rate, blood pressure and body temperature were all higher during ad libitum than restricted feeding, and heart rate and body temperature were higher by day (12 h) than at night (12 h). The decreases in heart rate and body temperature at night were greater during restricted than ad libitum feeding. Blood pressure tended to be higher at night, except in year 2 during restricted feeding. Body temperature and ambient temperature were higher in year 2 than year 1.3. During restricted feeding, marked peaks in heart rate, blood pressure and body temperature in the 15 min after provision of the daily food ration at 09:00 h, when birds were eating, were equivalent to corresponding values seen during ad libitum feeding.4. Relative powers in delta (1 to 4 Hz) and theta (4 to 8 Hz) frequency bands of the EEG power spectrum were higher at night in year 2 only, while power in the alpha (8 to 12 Hz) band was higher at night in both years.5. It is concluded that most of the variation in heart rate, blood pressure and body temperature between feeding states and times of day/night can be accounted for in terms of variation in food intake and energy expenditure. The greater slow wave (delta, theta) EEG activity seen after lights-off in year 2 may reflect non-paradoxical sleep at that time.

Influence of food restriction on dopamine receptor densities, catecholamine concentrations and dopamine turnover in chicken brain.

To investigate further a putative role of dopamine in control of food restriction-induced behavioural stereotypies, chickens were fed during rearing on either a daily restricted ration recommended by a breeding company, twice the recommended restricted ration, or ad libitum food. They were killed at 60 days of age and their excised brains were dissected into six regions and homogenized. Densities of dopamine D1 and D2 receptors were assessed, after first estimating binding parameters for [3H]SCH 23390 (D1) and [3H]spiperone (D2) in chicken brain homogenates. Specific binding of both ligands was highest in basal telencephalon. Concentrations of dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid were also highest in basal telencephalon, whereas noradrenaline and adrenaline levels were highest in diencephalon. Dopamine concentration in basal telencephalon and noradrenaline concentration in diencephalon were increased significantly in response to food restriction, but no effect of feeding treatment was found in dopamine turnover, adrenaline levels, or D1 and D2 receptor densities in any brain region studied. The observed changes in brain catecholamine levels are consistent with roles for dopaminergic and adrenergic mechanisms in the control of food restriction-induced behavioural stereotypies in chickens.

Application of a radiotelemetry system for chronic measurement of blood pressure, heart rate, EEG, and activity in the chicken.

This paper reports the first successful chronic monitoring (for 30 days) of blood pressure, heart rate, EEG, and physical activity in a freely moving bird, following (described) implantation of a commercially available (Data Sciences International) radiotelemetry device in a 1.6-kg broiler chicken. The tip of the device's pressure sensing catheter was introduced into the descending aorta via a leg (ischiadic) artery and, although the catheter was tied in place, circulation in the leg was maintained and leg function was not impaired. EEG was recorded from the device's paired sensing electrodes positioned on the surface of the telencephalon. Physiological and activity data collected by the radiotelemetry system over 2 complete 24-h periods, 1 and 4 weeks after implantation of the device, were analyzed with the system's own (Dataquest LabPRO) analysis software. The results presented are discussed mainly in terms of variation between light and dark periods.

Behavioral responses of restricted-fed fowls to pharmacological manipulation of 5-HT and GABA receptor subtypes.

Effects on environmentally induced oral stereotypies (object pecking and drinker-directed activity) and other behavior (sitting, standing, pacing, preening), of preferential antagonists and agonists of central 5-HT and GABA receptor subtypes, were examined in individually caged broiler breeder fowls subjected to chronic food restriction. All drugs were injected intravenously at three doses, and their effects compared with a saline control treatment. The only significant (p < 0.05) effect of 5-HT antagonists [NAN-190 (5-HT1A), ketanserin (5-HT2), MDL-72222 (5-HT3)] was an increase in pacing with ketanserin (0.8 mg/kg). With 5-HT agonists, 8-OH-DPAT (5-HT1A) suppressed the two oral stereotypies and increased standing (all 1.0 mg/kg) and preening (0.2 mg/kg), alpha-methylserotonin (5-HT2) suppressed the oral stereotypies and increased sitting (all 1.0 mg/kg), and m-CPBG (5-HT3) suppressed drinker-directed activity (1.0 mg/kg). The GABA antagonists (bicuculline (GABAA), 5-aminovaleric acid (GABAB) had no effect, and of the GABA agonists [muscimol (GABAA), baclofen (GABAB)], muscimol suppressed preening and increased sitting, standing (all 1.0 mg/kg), and pacing (0.2 mg/kg). Most of the significant effects of serotonergic and GABAergic agents on behavior here appeared to reflect at least some degree of sedation, and there was no real evidence of any specific influence of these compounds on the oral stereotypies within the range of doses tested.

The role of adrenoreceptors in control of stereotyped oral behavior in restricted-fed fowls.

Effects on environmentally induced oral stereotypies (object pecking and drinker-directed activity) of preferential antagonists and agonists of adrenoreceptor subtypes were examined in individually caged broiler breeder fowls subjected to chronic food restriction. Three drugs in each category were injected intravenously at three doses, and their effects compared with a saline control treatment. With the antagonists, object pecking was suppressed more by prazosin (alpha 1) and propranolol (beta) than by yohimbine (alpha 2), while drinker-directed activity showed delayed stimulation with yohimbine and propranolol. With the agonists, drinker-directed activity was suppressed more by clonidine (alpha 2) than by isoproterenol (beta) and phenylephrine (alpha 1), while object pecking was inhibited by the high doses of clonidine and isoproterenol but showed delayed stimulation with the low dose of clonidine and (nonsignificantly) the high dose of phenylephrine. Initial suppression of both oral stereotypies by the high doses of yohimbine and isoproterenol, and high and medium doses of clonidine, may have been due to sedation, because in those instances it coincided with increased sitting, an activity not normally seen. Increased standing with clonidine and the medium dose of yohimbine may also reflect sedation. When there were no significant increases in sitting or standing to indicate sedation, responses of both stereotypies were essentially the same with all three adrenoreceptor subtypes; i.e., object pecking was inhibited by the antagonist but not the agonist, while drinker-directed activity was inhibited by the agonist but not the antagonist. It is concluded that alpha 1, alpha 2, and beta adrenoreceptors are all implicated in expression of these stereotypes, and that the two activities may be differentially controlled.

Influence of pharmacological manipulation of dopamine and opioid receptor subtypes on stereotyped behaviour of restricted-fed fowls.

Effects on environmentally induced oral stereotypes (object pecking and drinker directed activity) of antagonists and agonists of dopamine and opioid receptor subtypes were examined in individually caged broiler breeder fowls subjected to chronic food restriction. Three drugs in each category were injected intravenously at three doses, and their effects compared with those of a saline control treatment. With dopamine antagonists, inhibition of both stereotypes was most marked with haloperidol (D2), intermediate with clozapine (D4), and lowest with SCH 23390 (D1). Increased sitting with the high doses of these three drugs may reflect sedation. With dopamine agonists, SKF 38393 (D1) suppressed both stereotypes slightly, quinpirole (D3) did so consistently and potently, possibly reflecting preferential presynaptic action, while bromocriptine (D2) inhibited drinker-directed activity consistently, but its initial suppression of object pecking changed to delayed stimulation with the high dose. This biphasic effect of bromocriptine may reflect change from pre- to postsynaptic action. Two of the opioid antagonists, naltrexone (mu) and MR 2266 (kappa, but also mu), inhibited object pecking partially, while naltrindole (delta) and the opioid agonists fentanyl (mu), BUBU (delta), and PD 117302 (kappa) had delayed and minor effects. These results suggest that expression of object pecking, but not necessarily drinker-directed activity, depends more on activation of D2 dopamine receptors than D1 receptors, the role of D3 and D4 receptors is less clear, and activation of mu and possibly kappa opioid receptors may play a contributory role.

Effects of exogenous melatonin on some endocrine, behavioural and metabolic parameters in Japanese quail Coturnix coturnix japonica.

1. Melatonin administration in drinking water (5 micrograms/ml) to Japanese quail resulted in a 20-fold increase of plasma melatonin levels in comparison with the control, day time concentration (0.34 +/- 0.05 vs 6.88 +/- 1.10 nmol/l). 2. Plasma triiodothyronine levels increased (5.8 +/- 0.93 vs 7.97 +/- 0.64 nmol/l), corticosterone decreased (28.04 +/- 3.42 vs 15.96 +/- 2.56 nmol/l) and no significant changes were recorded in thyroxine concentration after the treatment. 3. A higher occurrence of sleeping and lower occurrence of pecking were found in melatonin treated quail. 4. Abdominal fat deposition as well as the content of total lipids in the breast muscle and triacylglycerols in plasma were decreased in treated birds indicating an inhibitory effect of melatonin on lipogenesis. 5. Melatonin increased RNA content in the breast muscle but did not affect plasma glucose concentration and body weight.

Behaviour of newly hatched and adult Japanese quail and the feasibility of adaptation to weightlessness.

The aim of cosmic biology is to create conditions necessary for the long-term stay of man on cosmic orbital complexes and planetary stations. Such conditions should be provided by the autonomous closed ecosystem--a simplified model of the terrestrial biocenosis. As an experimental model of the higher heterotrophic link of this ecosystem the Japanese quail was chosen. This paper presents recent knowledge on the behaviour of newly hatched and adult quails under conditions of weightlessness. Videorecords made as part of the experiments aboard the MIR orbital station do not meet the criteria of systematic behavioural observation required for qualitative and quantitative behavioural analysis on earth. Nevertheless, the data is highly interesting and original, and was therefore analysed and summarized.