Biomedical subjects

M Langella

Publications and source records attributed to M Langella.

14 recordsLinked to original sources

PubMed1992

The sequential hypothesis of sleep function. III. The structure of postacquisition sleep in learning and nonlearning rats.

EEG methods were used to examine the structure of postacquisition sleep in learning (L) and nonlearning (NL) rats previously exposed to a session of two-way active avoidance training, and in control rats (C) left in their home cages. In agreement with literature data, the number and total amount of paradoxical sleep (PS) episodes were higher in L rats than in NL rats. In addition, significant differences between L and NL rats concerned the episodes of synchronized sleep followed by wakefulness or by PS (SS-W and SS-PS, respectively). The average duration and related parameters of SS-W episodes, and the average duration, number, amount and related parameters of SS-PS episodes increased in NL and L rats in comparison with C rats. Longer SS-W episodes occurred early in NL and L rats, but the effect lasted longer in NL rats. On the other hand, the increments concerning SS-PS episodes occurred earlier, were more pronounced and laster longer in L rats. The results support a role of SS in brain information processing, as envisaged by the sequential hypothesis on the role of sleep. They suggest, furthermore, that memory traces lacking adaptive value may be destabilized and cleared away during SS-W and SS-PS episodes, while the remaining memory traces may be retained and eventually stored again in more integrated form during SS-PS and PS episodes, respectively.

Animals↗

PubMed1992

The sequential hypothesis of sleep function. IV. A correlative analysis of sleep variables in learning and nonlearning rats.

Female adult rats were trained for a two-way active avoidance task (4 h), and allowed free sleep (3 h). Control rats (C) were left in their home cages during the acquisition period. Dural electrodes and an intraventricular cannula, implanted one week in advance, were used for EEG recording during the period of sleep and for the injection of [3H]thymidine at the beginning of the training session, respectively. Rats were killed at the end of the sleep period, and the DNA-specific activity was determined in the main brain regions and in liver. Correlations among sleep, behavioral and biochemical variables were assessed using Spearman's nonparametric method. In learning rats (L), the number of avoidances was negatively correlated with SS-W variables, and positively correlated with SS-PS variables (episodes of synchronized sleep followed by wakefulness or paradoxical sleep, respectively) and with PS variables. An inverse pattern of correlations was shown by the number of escapes or freezings. No correlations occurred in rats unable to achieve the learning criterion (NL). In L rats, the specific activity of brain DNA was negatively correlated with SS-W variables and positively correlated with SS-PS variables, while essentially no correlation concerned PS variables. On the other hand, in NL rats, comparable correlations were positive with SS-W variables and negative with SS-PS and PS variables. Few and weak correlations occurred in C rats. The data support a role of SS in brain information processing, as postulated by the sequential hypothesis on the function of sleep. In addition, they suggest that the elimination of nonadaptive memory traces may require several SS-W episodes and a terminal SS-PS episode. During PS episodes, adaptive memory traces cleared of nonadaptive components may be copied in more suitable brain sites.

Animals↗

PubMed1991

Active polysomes in the axoplasm of the squid giant axon.

Axons and axon terminals are widely believed to lack the capacity to synthesize proteins, relying instead on the delivery of proteins made in the perikaryon. In agreement with this view, axoplasmic proteins synthesized by the isolated giant axon of the squid are believed to derive entirely from periaxonal glial cells. However, squid axoplasm is known to contain the requisite components of an extra-mitochondrial protein synthetic system, including protein factors, tRNAs, rRNAs, and a heterogeneous family of mRNAs. Hence, the giant axon could, in principle, maintain an endogenous protein synthetic capacity. Here, we report that the squid giant axon also contains active polysomes and mRNA, which hybridizes to a riboprobe encoding murine neurofilament protein. Taken together, these findings provide direct evidence that proteins (including the putative neuron-specific neurofilament protein) are also synthesized de novo in the axonal compartment.

Animals↗

PubMed1984

Innervation pattern of intrinsic laryngeal musculature of the rabbit.

The intrinsic laryngeal musculature of rabbit was studied using various neurohistological techniques. The vegetative and sensory nerve terminals are present in abundance, while the proprioceptors are seemingly absent. Furthermore, simple motor endplates, sometimes furnished with ultraexpansional fibers, complex endplates, or 'en grappe' are described. Their abundance within a musculature lacking in muscle-spindles is indicative of a possible vicarious function.

Animals↗

PubMed1983