Avoidance of stomas and delayed anastomosis for bowel necrosis: the ''clip and drop-back'' technique

Necrotizing enterocolitis (NEC) and midgut volvulus (MGV) often are associated with extensive bowel necrosis. These cases may require extensive enterectomy and the formation of high or multiple stomas, and frequently are complicated by short bowel syndrome, excessive fluid losses, fistulas, stenosis, and skin breakdown. This report describes a "clip and drop-back" technique, followed by delayed anastomosis performed 48 to 72 hours later. The technique was successful in five severely ill infants (3 NEC, 2 MGV) with extensive necrosis, bowel perforation(s), and peritonitis, who required either a high stoma near the ligament of Treitz or multiple resections and enterostomies. This method removes obvious necrotic perforated bowel, controls contamination, avoids stomas (and their inherent complications in this age group), and preserves bowel length. All five babies survived. The technique is a useful addition to the pediatric surgeon's operative armamentarium in selective cases.     

Effect of reinforcer devaluation on discriminative control of instrumental behavior.

Two experiments examined the effect of reinforcer devaluation on the ability of a discriminative stimulus (Sd) to control instrumental behavior in Sprague-Dawley rats. In Experiment 1 reinforcer devaluation reduced, but did not eliminate, the ability of the Sd to control performance of the original response and to transfer its control to a new response trained with the same reinforcer. The effect of devaluation was more complete in Experiment 2, in which the reinforcer was delivered directly into the oral cavity. However, retraining the response with a different reinforcer partially restored the ability of the Sd to control performance of that response. These results suggest that an Sd may not augment its trained responses when the reinforcer has been completely devalued but may promote responses with which it shares a reinforcer, as long as those responses are associated with some reinforcer that retains its value. The implications of these results for the way that discriminative stimuli control instrumental behavior are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative changes in excitors and inhibitors differ when they are conditioned in compound.

When an AB stimulus compound is reinforced or nonreinforced, there are associative changes in both A and B elements. In many contemporary theories those changes are viewed as governed by a common error term, computed as the discrepancy between the total associative strength of the AB compound and that supported by the trial consequence. This implies that if A and B are equally salient, then the magnitude of their associative change should be the same, whatever their strengths prior to the AB trial. This implication was explored for a compound consisting of an excitatory A and an inhibitory B. A novel assessment procedure avoided the difficulty of making comparisons at different locations on the performance scale. Three experiments using a magazine approach preparation in rats and 3 using autoshaping in pigeons found evidence contradicting this implication. The excitatory A changed less than the inhibitory B when the compound was reinforced but more than B when the compound was nonreinforced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning of stimuli with nonzero initial value.

In five experiments, rats received conditioning of either moderately attractive or moderately aversive flavors using either a strongly negative lithium chloride (LiCl) or a strongly positive Polycose as the reinforcer. In each case, testing was done with a compound of the two moderately valued stimuli to determine the amount of associative change produced by the pairing. In both within-subject and between-subjects designs, the amount of associative change was greater for a signal whose moderate value was opposite in valence from that of the reinforcer. This suggests that, like learned stimulus value, inherent stimulus value can modulate further associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facilitation and excitation.

Conducted 3 experiments using an autoshaping procedure in 46 female Carneaux pigeons to examine the facilitation that develops to B in an ABA+ paradigm. Results indicate that when B is a diffuse stimulus and A is a localized key light, this paradigm results in B's facilitating the pecking at A. Prior Pavlovian excitatory conditioning of B interfered with its developing facilitation. However, prior Pavlovian excitatory conditioning of A allowed even an excitatory B to develop facilitation. Results suggest that there is a functional reciprocal relation between B's excitation and facilitation. However, that relation is apparently mediated by the conditioning of A. To the degree that B develops excitatory strength, it can block the conditioning of A. That in turn will undermine B's ability to develop facilitory control over responding to A. As a result, an ABA+ discrimination can be solved either by B's becoming excitatory (and A's remaining neutral) or by B's becoming a facilitator (of the excitatory A). However, no evidence was found for an inherent competition between excitation and facilitation. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phonetic profiles of toddlers with specific expressive language impairment (SLI-E)

Spontaneous language samples of 30 24-month-old toddlers diagnosed with Specific Expressive Language Impairment (SLI-E) were compared with samples produced by an age-matched group of 30 typically developing toddlers. Vocalization patterns, phonetic inventories, and syllable formation patterns were compared. Toddlers with SLI-E vocalized significantly less often than their typically developing peers, had proportionately smaller consonantal and vowel inventories, and used a more restricted and less mature array of syllable shapes. Although the mean incidence of phoneme usage varied significantly in all comparisons, profiles of consonant usage were similar between the two groups for initial phoneme usage, but considerably different for final consonant closure. Such patterns of vocal and phonetic behavior confirm earlier reports of phonetic delay in SLI-E, and suggest that nongrammatical factors contribute to the development of expressive language deficits in toddlers. We further propose a bidirectional model for the expressive deficits in SLI-E, in which the child's limited phonetic capacity interacts with propensities in caretaker interaction to further reduce opportunities for expressive language learning and practice.     

Effect of inflation of the unconditioned stimulus value following conditioning.

Conducted 3 experiments using a conditioned suppression procedure in male Sprague-Dawley rats. Exp I and II (N = 56) found that exposure to a more severe shock either before or after conditioning elevated the CR established by a moderate shock. Exp III (n = 32) found 2nd-order conditioning immune to such modification. These findings parallel earlier results with habituation of the UCS in the absence of the CS. They encourage the view that organisms form memories of the UCS independently of associative connections with the CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Redundant treatment of neutral and excitatory stimuli in autoshaping.

Five autoshaping experiments with pigeons exposed excitatory and neutral stimuli to treatments that made those stimuli uninformative with respect to the unconditioned stimulus (US). Experiment 1 found that adding sufficient USs in the absence of the conditioned stimulus (CS) to make it uninformative prevented conditioning of that CS but did not undermine conditioning of a previously trained CS. Experiment 2 found a similar data pattern when an excitatory or neutral B stimulus was embedded in an A+/BA+ paradigm with an excitatory A. Experiments 3–5 verified that finding when the salience of A and B or the conditioning level of B was varied. These results, which are largely unanticipated by current theories of conditioning, suggest that the consequences of making a stimulus redundant depend on its conditioning level prior to that treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of context in autoshaping.

Three experiments used an autoshaping procedure in 64 female White Carneaux pigeons to investigate the conditioning of the context and of a discrete CS with a food UCS. CS–UCS associations were measured by directed pecking at the key light CS; context–UCS associations were assessed by general activity in the context. Exp I investigated the influence of context–UCS associations on performance to a previously trained CS. The same CS produced greater keypecking in a context of higher associative strength. Exp II examined the influence of context–UCS associations on learning of CS–UCS associations. When tested in a context of fixed associative strength, a CS that had been trained in a context of high associative strength elicited less responding than one trained in a context of low associative strength. Exp III found that signaling a UCS by a discrete CS interfered with the formation of context–UCS associations, as measured both in terms of general activity and ability to promote responding to another CS. Results suggest that the context and the CS compete for association with the UCS. They also suggest that context–UCS associations facilitate the exhibition of CS–UCS associations. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)