Habituation: effects of regular and stochastic stimulation

The different effects of regular and stochastic stimulation on the flexor reflex of patients with the spinal cord totally divided and of normal subjects and on the blink reflex of normal subjects were studied. When the cutaneous stimulus was above but less than twice threshold, with regular stimulation habituation occurred; with stochastic stimulation, habitutaion either did not occur or it was minimal. Stochastic stimulation was at random stimulus intervals or with random stimulus intensities. When stimulus intensity was around threshold, habituation occurred with both kinds of stimulation, the response to stimulation soon ceasing to occur. When stimulus intensity was greater than twice threshold, habituation did not occur with both kinds of stimulation. When regular stimulation was given after the response had ceased to occur, extinction of the response beyond zero occurred. When a dishabituating stimulus was repeatedly applied in a regular manner, habituation to the dishabituating stimulus occurred. With regular and stochastic stimulation given as conditioning and test series, it was seen that stochastic stimulation caused, in addition to the short-term excitatory effect, the same long-term cumulative depressing effect on excitability as did regular stimulation

On Common Sense, Estimation, and the Soul’s Unity in Avicenna

This paper addresses two questions related to Themistius’ alleged influence on Avicenna’s theory of the common sense. The first question concerns the phenomenon of incidental perception, which Themistius explained by means of the common sense. For Avicenna, on the contrary, the explanation of cases like our perceiving something yellow as honey involves the faculty of estimation and the entire system of the internal senses that he coined, and this results in an analysis that is considerably more complex than Themistius’. The second question concerns Themistius’ claim according to which an incorporeal spirit is the primary subject of perception. I argue that Avicenna departs from such a view both because for him spirit is a corporeal substance and because he insists that the subject of all cognition is the soul, not any of its faculties. Finally, I conclude by briefly considering other, more general ways in which Themistius could have influenced Avicenna’s psychology.peerReviewe

Disorders of hemostasis during the surgical management of severe necrotizing pancreatitis

Objectives: Several clinical studies of severe necrotizing pancreatitis ( SNP) suggest profound activation of coagulation as well as activation of the fibrinolytic system. The aim of this study was to evaluate the hemostatic derangements in patients who were managed for SNP. Methods: Forty-one operated-on patients with SNP were analyzed regarding clinical outcome and activation of the coagulation systems. Serial measurement of coagulation, anticoagulation, and fibrinolysis parameters: prothrombin time ( PT), activated partial thromboplastin time (APTT), fibrinogen, antithrombin III ( AT III), protein C, plasminogen activator inhibitor-1 (PAI-1), D-dimer, alpha(2)-antiplasmin, and plasminogen were performed on days 1, 3, 5, 7, 10, and 14 after the initial operation. According to treatment outcome at the end of study, groups of 26 survivors and 15 nonsurvivors were compared. Results: Nonsurvivors had significantly lower levels of activity of protein C and AT III, and higher concentrations of D-dimer and PAI-1 than survivors. The other measured parameters did not show significant differences between the compared groups of patients. Conclusions: Changes in protein C, AT III, D-dimer and PAI-1 levels indicate exhaustion of fibrinolysis and coagulation inhibitors in patients with poor outcome during the course of SNP

Common Sense in Themistius and its Reception in the pseudo-Philoponus and Avicenna

In his paraphrase of the De anima Themistius provides an account of Aristotle’s doctrine of common sense that combines Alexander of Aphrodisias and Plotinus. The Aristotelian koine aisthesis is interpreted as the unifying power of an incorporeal pneuma that receives the information from the senses, the messengers of the soul. On the basis of this Plotinian tenet, Themistius describes the koine aisthesis as a spiritual power that unifies diverse and even opposite sensorial inputs, and discriminates between them. This interpretation of koine aisthesis was influential in subsequent Greek works on the De anima from late Antiquity (pseudo-Philoponus) to Byzantine times (Sophonias) and inspired Avicenna