[Endovascular stent-assisted angioplasty after cervical arteries dissection]. / Angioplastie-stenting transluminale percutanée après dissection des troncs supra-aortiques.

INTRODUCTION: Spontaneous dissection of cervical arteries is one of the major causes of stroke in young patients. The recommended treatment is curative anticoagulation. However, in selected cases, this treatment could fail or meet contraindications. In such cases, an endovascular stent-assisted angioplasty could be successful. CASE REPORT: We report the case of a 47-year-old patient with spontaneous dissection of the carotid and vertebral arteries. Despite optimized anticoagulant therapy, cerebral perfusion was low. An endovascular stent-assisted angioplasty was performed in the intra- and extracranial segments of the right internal carotid artery. Consequently by improving the intracranial circulation, normal functioning was restored with no immediate complications and the patient remained free of complications at 16-month follow-up. CONCLUSION: Dissections of cervical arteries that lead to a chronic reduction in brain perfusion might benefit from endovascular stent-assisted angioplasty.

The behavioral economics of choice and interval timing.

The authors propose a simple behavioral economic model (BEM) describing how reinforcement and interval timing interact. The model assumes a Weber-law-compliant logarithmic representation of time. Associated with each represented time value are the payoffs that have been obtained for each possible response. At a given real time, the response with the highest payoff is emitted. The model accounts for a wide range of data from procedures such as simple bisection, metacognition in animals, economic effects in free-operant psychophysical procedures, and paradoxical choice in double-bisection procedures. Although it assumes logarithmic time representation, it can also account for data from the time-left procedure usually cited in support of linear time representation. It encounters some difficulties in complex free-operant choice procedures, such as concurrent mixed fixed-interval schedules as well as some of the data on double bisection, which may involve additional processes. Overall, BEM provides a theoretical framework for understanding how reinforcement and interval timing work together to determine choice between temporally differentiated reinforcers.

[Gaucher Disease type 1 mimicking immune thrombocytopenia: Role of hyperferritinemia and hypergammaglobulinemia in the initial evaluation of an isolated thrombopenia]. / Maladie de Gaucher de type 1 simulant une thrombopénie immunologique : intérêt de l'hyperferritinémie et de l'hypergammaglobulinémie dans le bilan d'une thrombopénie isolée.

INTRODUCTION: Gaucher disease type 1 is a rare genetic disease. It can cause thrombocytopenia. Current guidelines do not support bone marrow examination in front of isolated thrombocytopenia if no evidence suggests malignant hemopathy. This strategy aiming at sparing unnecessary investigations makes such rare diseases more difficult to diagnose. CASE REPORT: A 31-year-old woman was diagnosed with immune thrombocytopenia according to current guidelines. She presented later with mild splenomegaly. Bone marrow aspirate smears showed Gaucher cells. Gaucher disease was then confirmed. Looking backward, initial biological clues (hyperferritinemia, hypergammaglobulinemia) should have enabled to consider the diagnosis. CONCLUSION: Gaucher disease type 1 can be responsible for apparently isolated thrombocytopenia. The disease must be looked for if the thrombocytopenia is associated with unexplained hypergammaglobulinemia or hyperferritinemia. Diagnosing immune thrombocytopenia without bone marrow sample requires to systematically pay attention to any clinical or biological abnormality, not to ignore rare differential diagnoses.

Chlordiazepoxide and dizocilpine, but not morphine, selectively impair acquisition under a novel repeated-acquisition and performance task in rats.

RATIONALE: Some classes of drugs can selectively affect learning (i.e., acquisition of behavior) at doses that do not affect performance (i.e., previously learned behavior). Some drugs (e.g., benzodiazepines) show selective effects on acquisition across a wide variety of tasks. Other drugs [e.g., N-methyl-D-aspartate (NMDA) antagonists and opiate agonists], however, show selective effects under some tasks, but not others. OBJECTIVES: The purpose of this study was to examine the effects of the NMDA-antagonist dizocilpine (0.01-0.3 mg/kg), the opiate-agonist morphine (1.0-17.0 mg/kg), and the benzodiazepine chlordiazepoxide (3.0-30.0 mg/kg) in rats under a novel repeated-acquisition and performance task. METHODS: Nose pokes to a correct location within a 2x3 stimulus array on a computer touch screen were reinforced with food. In the acquisition component, the correct location changed across sessions but remained constant within sessions; in the performance component, the correct location was constant both across and within sessions. RESULTS: Both chlordiazepoxide and dizocilpine selectively impaired accuracy in the acquisition component at doses that did not affect accuracy in the performance component or overall response speed. Morphine, however, did not affect acquisition without affecting performance or response speed. CONCLUSIONS: These results with rats resembled those previously obtained for response-sequence learning in primates, rather than those previously reported for spatial learning in rats. Therefore, previous discrepancies in results for NMDA antagonists and opiate agonists across tasks probably were not a function of the species studied, but, rather, they more likely were a function of unique variables controlling acquisition within each task.

Timescale invariance and Weber's law in choice.

Pigeons were exposed to concurrent schedules for which reinforcement was alternately available at different times for each of two choices. In Experiment 1 (in which reinforcement times progressed arithmetically), overall, but not relative, response rate was timescale invariant. In Experiment 2 (in which reinforcement times progressed geometrically and were more spaced out), there was temporal control at all reinforcement times, but the amplitude of left-right response alternation decreased as time in the trial increased. These results indicate that the temporal regulation of both overall and relative response rates conforms to Weber's law although relative rate is heavily influenced by processes other than timing. It also adds support to the idea that overall and relative response rate reflects the operation of two independent processes.

Assessing spatial vision - automated measurement of the contrast-sensitivity function in the hooded rat.

The contrast-sensitivity function (CSF) provides a concise and thorough description of an organism's spatial vision; it is widely used to describe vision in animals and humans, to track developmental changes in vision, and to compare vision among different species. Despite the predominance of rats in neuroscience research, their vision is not thoroughly studied due to the complexity of psychophysical measurement and a generally held notion that rat vision is poor. We therefore designed an economical and rapid method to assess the hooded rat's CSF, using a computer monitor to display stimuli and an infrared touch screen to record responses. A six-alternative forced-choice task presented trials in which a sine-wave grating (S+), varying in spatial frequency and contrast, was displayed at different locations along with five gray stimuli (S-). Nose pokes to the S+ but not the S- produced water reinforcers. Contrasts were tested at each spatial frequency with a simple adaptive procedure until stimulus detection fell below chance. Psychometric functions were obtained by maximum-likelihood fitting of a logistic function to the raw data, obtaining the threshold as the function's point of inflection. As in previous studies with rats, CSFs showed an inverse-U shape with peak sensitivity at 0.12 cyc/deg and acuity just under 1 cyc/deg. The results indicate the present computer-controlled behavioral testing device is a precise and efficient instrument to assess spatial visual function in rats.

Immediacy versus anticipated delay in the time-left experiment: a test of the cognitive hypothesis.

In the time-left experiment (J. Gibbon & R. M. Church, 1981), animals are said to compare an expectation of a fixed delay to food, for one choice, with a decreasing delay expectation for the other, mentally representing both upcoming time to food and the difference between current time and upcoming time (the cognitive hypothesis). The results of 2 experiments support a simpler view: that animals choose according to the immediacies of reinforcement for each response at a time signaled by available time markers (the temporal control hypothesis). It is not necessary to assume that animals can either represent or subtract representations of times to food to explain the results of the time-left experiment.

Opioid antagonist effects on self-injury in adults with mental retardation: response form and location as determinants of medication effects.

The opioid antagonist naltrexone was administered to 8 adults with severe or profound mental retardation and extensive histories of self-injurious behavior. Five-minute behavioral samples were observed randomly out of every hour from 8 a.m. through 3 p.m., Monday through Friday, for four 2-week phases (baseline, placebo, 50 mg, and 100 mg). During naltrexone administration, there were fewer days with frequent head-banging and self-biting, whereas there were more days on which blows to the head or self-biting were infrequent. Self-injurious participants slept 1.38 hours less per night during baseline, which was unaffected by naltrexone.

Discrimination theory of rule-governed behavior.

In rule-governed behavior, previously established elementary discriminations are combined in complex instructions and thus result in complex behavior. Discriminative combining and recombining of responses produce behavior with characteristics differing from those of behavior that is established through the effects of its direct consequences. For example, responding in instructed discrimination may be occasioned by discriminative stimuli that are temporally and situationally removed from the circumstances under which the discrimination is instructed. The present account illustrates properties of rule-governed behavior with examples from research in instructional control and imitation learning. Units of instructed behavior, circumstances controlling compliance with instructions, and rule-governed problem solving are considered.

Pigeons' preference for free choice: number of keys versus key area.

In concurrent-chains schedules, pigeons prefer terminal links that provide two keys correlated with reinforcers (free choice) over those that provide only one key (forced choice), terminal-link reinforcement rates being equal. With same-size keys, free choice provides a larger area available for pecking. Preferences were examined using terminal links that differed in key number only (one or two) or key size only (small and medium or medium and large), or that equated the area of the two free-choice keys with that of the forced-choice key. Medium (standard) keys were typically preferred to small keys, but indifference was typically obtained between medium and large keys. The size preference usually overrode free-choice preference with one medium key pitted against two small keys, but free-choice preference was reliably observed with one large key pitted against two medium keys. In other words, preferences were a joint function of key number and key area, implying that free-choice preference is not reducible to preference for larger key areas. Free-choice preference requires separate keys rather than larger areas; the relevant behavioral units are the discriminated operants correlated with each terminal-link key rather than classes defined by topographical features such as area or perimeter.

Rapid determinations of preference in multiple concurrent-chain schedules.

With concurrent chains arranged for a pigeon's key pecks, pecks on two concurrently available initial-link keys (left and right) respectively produce separately operating terminal links (A and B). Preferences for terminal link A over terminal link B are usually calculated as deviations of relative initial-link response rates (left divided by total pecks) from those during baseline conditions, when A equals B. Baseline preferences, however, are often variable and typically are determined indirectly (e.g., with unequal A and B, reversing left-right assignments of A and B over sessions and estimating the baseline from differences between the relative rates generated). Multiple concurrent-chain schedules, with components each consisting of a pair of concurrent chains, speed the determination of preferences by arranging A and B and their reversal within sessions. In two experiments illustrating the feasibility of this procedure, one component operated with circles projected on initial-link keys and the other with pluses; when left and right initial-link pecks respectively produced terminal links A and B in one component, they produced B and A in the other. Even as the baselines fluctuated, preference was observable within sessions as the difference between relative initial-link response rates in the two components. The first experiment demonstrated the rapid development of preferences when terminal links A and B consisted of fixed-interval 15-s and 30-s schedules. The second demonstrated the sensitivity of the procedure to preference for a fixed-interval 30-s schedule operating for pecks on either of two keys (free choice) over its operating for pecks on only a single key (forced choice).

Time and rate measures in choice transitions.

Three experiments with pigeons studied the relation between time and rate measures of behavior under conditions of changing preference. Experiment 1 studied a concurrent chain schedule with random-interval initial links and fixed-interval terminal links; Experiment 2 studied a multiple chained random-interval fixed-interval schedule; and Experiment 3 studied simple concurrent random-interval random-interval schedules. In Experiment 1, and to a lesser extent in the other two experiments, session-average initial-link wait-time differences were linearly related to session-average response-rate differences. In Experiment 1, and to a lesser extent in Experiment 3, ratios of session-average initial-link wait times and response rates were related by a power function. The weaker relations between wait and response measures in Experiment 2 appear to be due to the absence of competition between responses. In Experiments 1 and 2, initial-link changes lagged behind terminal-link changes. These findings may have implications for the relations between fixed- and variable-interval procedures and suggest that more attention should be paid to temporal measures in studies of free-operant choice.

[Serious clinical manifestations of vitamin deficiency after a "sleeve" gastrectomy: role of psychogenic anorexia]. / Anorexie psychogène et carences vitaminiques sévères dans les suites d'une gastrectomie longitudinale.

INTRODUCTION: Morbid obesity is an emerging condition in the general population. Bariatric surgery, which has demonstrated its effectiveness for weight loss, mortality and morbidity related to obesity, is required in some patients. However, it may be associated with various adverse effects, including vitamin deficiencies. CASE REPORT: We report a 33-year old man who presented central and peripheral neurological deficits and cardiac manifestations related to multiple vitamin deficiencies, following "sleeve" gastrectomy. The vitamin deficiencies were related to insufficient ingesta secondary to psychogenic anorexia. The patient improved with vitamins, antidepressant drugs and atypical neuroleptics. CONCLUSION: Post-operative complications of "sleeve" gastrectomy include vitamin deficiencies that can develop in the context of psychogenic anorexia and ingesta reduction, in the absence of any digestive malabsorption.

Rapid, accurate time estimation in zebrafish (Danio rerio).

Zebrafish were tested in an appetitive Pavlovian delayed conditioning task. After an intertrial interval of k*T s (k=11.25; T=8, 16 or 32 s), a small, translucent vertical pole was illuminated (CS) for T s. Food was presented at T/2 s. Pole-biting response latencies from CS onset were a linear function of the food delay T/2, with slope approximating unity (proportional timing), and standard deviation proportional to latency (scalar timing). Response latencies tracked changes in food delays even when they changed every other day. These findings are significant because the zebrafish genome has recently been sequenced, opening the door to studies in the genetics of interval timing.

Effects of MDMA, methamphetamine and methylphenidate on repeated acquisition and performance in rats.

Repeated-acquisition procedures that include performance controls for effects not specific to acquisition permit the assessment of drug effects on learning on a within-subject, within-session basis. Despite the advantages of this methodology, few studies have examined effects of psychomotor stimulants on repeated acquisition in rodents. The purpose of the present study was to investigate the effects of methylenedioxymethamphetamine (MDMA, 0.3-10mg/kg), methamphetamine (MA, 0.1-3mg/kg) and methylphenidate (MPD,1-17 mg/kg) using repeated-acquisition procedures with performance controls in rats using a touch-screen apparatus. Rats were presented a 2x3 array of stimuli using a computer touch-screen and nose-pokes to target locations within the array were reinforced. In the acquisition component, the correct location changed across sessions, whereas during the performance component, the correct location was constant across sessions. All three drugs reduced accuracy of responding to target locations in a dose-dependent fashion. None of the compounds enhanced learning at any dose. MPD and MA produced significant disruptions of acquisition accuracy only at doses that also disrupted performance, but the 3mg/kg dose of MDMA impaired acquisition of target responding without affecting performance. The selective impairment of acquisition found in the present study adds to the evidence of learning and memory disruption produced by acute MDMA administration and raise questions about the mechanisms for these actions.

Operant conditioning.

Operant behavior is behavior "controlled" by its consequences. In practice, operant conditioning is the study of reversible behavior maintained by reinforcement schedules. We review empirical studies and theoretical approaches to two large classes of operant behavior: interval timing and choice. We discuss cognitive versus behavioral approaches to timing, the "gap" experiment and its implications, proportional timing and Weber's law, temporal dynamics and linear waiting, and the problem of simple chain-interval schedules. We review the long history of research on operant choice: the matching law, its extensions and problems, concurrent chain schedules, and self-control. We point out how linear waiting may be involved in timing, choice, and reinforcement schedules generally. There are prospects for a unified approach to all these areas.

Cytoskeletal features of rat aortic cells during development. An electron microscopic, immunohistochemical, and biochemical study.

Actin, vimentin, desmin, and tropomyosin distribution in rat aortic endothelial and smooth muscle cells has been studied during development using fetal (18 to 20 days of gestation), and 5- and 14-day-, and 5-, and 12-week-old rats. Endothelial cells of newborn animals actively replicate and contain many actin stress fibers, whereas, in adult animals, replication is minimal and actin stress fibers are rare. The actin, vimentin, desmin, and tropomyosin content of smooth muscle cells increases gradually from fetal to adult animals. The number of desmin-containing cells also increases from 13% in fetal rats to 51% in adult rats. The beta-actin isoform is predominant in fetal and newborn animals, but gradually the alpha-isoform becomes quantitatively the most important, as seen by bidimensional polyacrylamide gels. Several analogies exist between the features of developing smooth muscle and what is known for developing striated muscle cells. The evolution of cytoskeletal features from fetal to adult animals is remarkably the opposite of what takes place in: (1) rat aortic smooth muscle cells proliferating after an endothelial injury, (2) human arterial smooth muscle cells present in atheromas, and (3) actively growing rat aortic smooth muscle cells in vitro. Thus, the assumption that pathological or cultured smooth muscle cells are "dedifferentiated" is supported by our biochemical observations.