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Biomedical subjects

C Franzini

Publications and source records attributed to C Franzini.

At least 91 records · Page 5Linked to original sources
PubMed1983

Automatic analysis of time-sequence parameters in unit cell activity.

A method is presented which allows to automatically evaluate, by the aid of a small computer, parameters concerning the way a sequence of spikes is organized in time. This method stands on few simple assumptions: Interspike Time Intervals (ITIs) and/or clusters of ITIs that are either "too large" or "too short" so as to be unlikely at 0.05 level on the basis of a Poissonian firing hypothesis are selected and assumed as "Low Firing Periods" (LFP) and "High Firing Periods" (HFP), respectively. General information is obtained about both LFPs and HFPs. Results on real cases are in agreement with previous studies on unit cell activity.

Animals↗
PubMed1983

Septal influences on the activity of hippocampal neurones during sleep.

Septal influences on CA1 and DG neurones were studied in sleeping cats before and after septal lesions suppressing the theta rhythm. Septal influences tonically gauge the activity level of a discrete group of CA1 and DG neurones, regardless of sleep stages. The observed splitting of each CA1 and DG population into two groups of units showing opposite changes in firing rate from SS to DS may be related to extraseptal inputs.

Animals↗
PubMed1982

Neural control of vasomotion in rabbit ear is impaired during desynchronized sleep.

In a warm environment the skin vessels of the rabbit ear, dilated during synchronized sleep (SS), reduce their caliber during desynchronized sleep (DS). In a cold environment the ear skin vessels, constricted during SS, increase their caliber during DS. These vascular changes contrast with thermoregulatory homeostasis. They can be accounted for by the decrease in both local transmural pressure and sympathetic vasoconstrictor discharge accompanying the DS phase. A decrease in local transmural pressure prevails in a warm environment and a decrease in sympathetic discharge in a cold environment. Accordingly, the vessel caliber decreases in the heat and increases in the cold. The results of the sympathetic denervation of the ear and of the alpha-receptor blockade confirm the passive nature of vascular changes in the rabbit ear during DS.

Animals↗
PubMed1981

Short-term thermoregulatory adjustments to ambient temperature changes in the rabbit. I. Theoretical model.

A model of thermoregulation is proposed, based on additive features found both in the processing of thermal information and in the interaction between thermoregulation and other vegetative functions. According to this model, it may be expected that, if temperature changes are induced in some thermal inputs, other thermal inputs will show specular temperature changes. The model has been experimentally tested.

Animals↗
PubMed1981

Short-term thermoregulatory adjustments to ambient temperature changes in the rabbit. II. Experimental results.

Rabbits housed at constant ambient temperature (Ta = 22 +/- 1 degree C) were exposed, in different sessions, to different Ta's, ranging from 0 to 25 degrees C. The steady values of both ear skin (Ts) and hypothalamic (Thy) temperature were measured. Ts appeared to be positively correlated with Ta, while, on the contrary, Thy was found to be negatively correlated with Ta. specular changes, therefore, were induced on Ts and Thy by Ta changes, according to the additive model proposed in a previous paper.

Animals↗
PubMed1981

Interactions between temperature regulation and emotional arousal in the rabbit.

In our study we examined, in the rabbit, the interactions between temperature regulation and the state of increased vigilance and emotional arousal induced by a Classical Aversive Conditioning Procedure. A Delay Conditioning Procedure was used. The Conditioned Stimulus (CS) was a 1350 Hz, 85 dB tone, the Unconditioned Stimulus (UCS) a 1 mA, 0.5 s shock. Testing sessions were run at different ambient temperatures from 5 to 30 degrees C. At all ambient temperatures considered the CS induced desynchronisation of the EEG and stereotyped changes in all the autonomic variables studied. Hypothalamic temperature (Thy) first increased, then decreased below its initial value, whereas ear skin temperature (Ts) showed opposite changes. Respiratory frequency (RF) initially increased, then tended to revert to its original value. The average time course of this complex pattern was 300 s from the CS. The overall effect of the CS sequence in a session was a significant decrease in Thy and Ts and a significant increase in RF compared to control values at the beginning of the session. Both in the short (single trial) and long terms (whole session) the autonomic responses induced by the emotional stress (polypnoea and vasoconstriction) were not coherent from the point of view of thermoregulation. The hypothesis of an effect of emotional arousal in shifting set point temperatures can therefore be discarded in favour of a direct action of emotional stress on effector controllers for respiration and vasomotion.

Animals↗
PubMed1981

[Evaluation of the methylthymol blue and orthocresolphthalein direct methods of determination of serum calcium].

Two methods for the direct colorimetric determination of serum calcium (BMT and OCFT) have been evaluated and compared with atomic absorption spectrophotometry (AAS). Both colorimetric methods resulted simple to use, but temperature-sensitive: values for the ratio absorbance at 10 degrees C/absorbance at 45 degrees C were 1.6 (BMT) and 1.8 (OCFT). When readings were taken at 37 degrees C good precision was achieved with both methods (between-the-series coefficients of variation were 3.5 divided by 2.2% for OFCT and 1.9 divided by 3.4% for BMT). No interference from bilirubin (up to 180 mumol/l) was observed with both methods; slight positive interference from haemoglobin (1 g/l) was observed only with OCFT method. Results from the two colorimetric methods closely agreed in the range 1.0 divided by 4.5 mmol/l: statistical analysis of comparison data gave BMT = 0.0963 + 0.9521 OCFT, r = 0.9820. From the results of direct comparison with AAS (103 serum specimens, concentration spanning from 1.0 to 4.5 mmol/l) statistical analysis gave: BMT (y)/AAS(x): y = 0.0721 + 1.0226x (r = 0.9678); OCFT(y)AAS(x): y = -0.0208 + 1.0720x (r = 0.9836): it is concluded that both methods show a slight positive bias with respect to AAS.

Bromthymol Blue↗
PubMed1980

Cutaneous vasomotion during REM sleep in the rabbit's ear, after alpha-receptor blockade.

Cutaneous vasoconstriction in the rabbit's ear during REM sleep in a warm environment is not abolished by alpha-receptor blockade (phenoxybenzamine 6 mg/kg i.v.), thus confirming that the vasomotor response during REM sleep is independent of the activity of circulating catecholamines. The decrease in cardiac output during REM sleep may be responsible for the slight fall in transmural pressure which underlies cutaneous ear vasoconstriction during REM sleep.

Adrenergic alpha-Antagonists↗
PubMed1980

Emotional hypothermia induced by classical aversive conditioning in the rabbit.

The CS induces a stereotyped change in all the autonomic variables studied: Ts decreases, RF and Thy increase. Within an average 300 sec from the CS a new steady state is reached, characterized by a lower Thy and a higher RF compared to the respective control values before the CS. Throughout the session the CS sequence determine a significant decrease in Thy which is analogous in our opinion with the "emotional hypothermia" induced in rabbits and rats by restraint.

Animals↗
PubMed1980

Analysis of differences between sequences of evoked unit responses.

Differences between sequences of evoked unit responses may concern the average number of spikes per response, the spike distribution inside the response, the "regularity" of such responses, etc. "Regularity" is defined and measured on the basis of the "distances" between consecutive responses. Each response can be characterized by a set of numbers allowing to represent it as a point in a multidimensional space. Distances between consecutive points are then measured in a euclidean way. Differences are eventually evaluated by proper statistical tests.

Computers↗
PubMed1980

Vasomotor adjustments in the rabbit's ear during REM sleep.

In the rabbit auricolar vessels constrict during REM sleep at high ambient temperatures (26-30 degrees C) and dilate a low ambient temperatures (0-5 degrees C). These opposite vasomotor adjustments during REM sleep are inconsistent with the logic of a thermoregulatory mechanism; they can only be understood as new equilibria of the vessels calibre to the drop in sympathetic vasoconstrictor tone and fall in transmural pressure during REM sleep. By cutting the sympathetic nerve supply to the ear we can rule out the neurogenic origin of ear vasoconstriction during REM sleep.

Animals↗
PubMed1980

[Number of retinal ganglion cells and visual discriminative performance in split-chiasma rats].

The relationship between post-operative retention, learning and transfer of visual discriminative tasks and number of retinal ganglion cells undegenerated after chiasma section was analyzed with a multiple linear regression program, stepwise procedure. Post-op retention of an intensity discrimination task significantly depends on the number of retinal ganglion cells in the most spared eye. Post-op learning and transfer of an orientation discrimination task significantly depends on 1) the total number of undegenerated ganglion cells and 2) their uniform distribution in both eyes.

Animals↗
PubMed1979

The retinal origin of uncrossed optic nerve fibres in rats and their role in visual discrimination.

An attempt was made to sever the optic chiasma in the mid-sagittal plane in 12 rats. This was successful in 8 animals. Provided there was no additional substantial damage to the uncrossed optic fibres the rats were able to relearn an intensity discrimination and to learn or relearn an orientation discrimination, although optokinetic following was abolished. The results unequivocally demonstrate that the uncrossed optic fibres can mediate two kinds of visual discrimination. The area of retina giving rise to the uncrossed fibres was determined from the position of undegenerated retinal ganglion cells in each eye following section of the chiasma, and in one eye of 4 rats in which one optic tract was entirely or extensively destroyed. The ganglion cells giving rise to the uncrossed optic fibres occupy about 40 degrees of the temporal retina, corresponding to the binocular overlap in the visual field.

Animals↗
PubMed1979

[The ipsilateral optic tracts in the rat. - I) Area of retinal origin].

An attempt was made to sever the optic chiasma in the mid-sagittal plane in 12 rats. This was successful in 8 animals. The area of retina giving rise to the uncrossed fibres was determined from the position of undegenerated retinal ganglion cells in each eye following section of the chiasma. The ganglion cells giving rise to the uncrossed optic fibres occupy about 40 degrees of the temporal retina, corresponding to the the binocular overlap in the visual field.

Animals↗