Periocular milia en plaque successfully treated by erbium:YAG laser ablation.

Milia en plaque in the periocular region represent a cosmetically disturbing skin condition of unknown origin characterized by numerous tiny milia grouped around the inner canthus and the medial aspect of both eyelids. While conservative treatment and manual expression often result in local recurrence, invasive approaches harbor the risk of mechanical or thermal injury of periocular skin and lid margins. A 32-year-old female patient with refractory periocular milia was treated with the erbium:YAG laser and followed-up for 12 months. Ablative laser treatment led to nearly complete resolution of the milia and an excellent clinical result. Importantly, no scarring, dyspigmentation or ocular complications were noted. This report demonstrates the efficacy and safety of erbium:YAG laser ablation of periocular milia. The precise control of tissue ablation with minimal thermal damage makes the erbium:YAG laser an ideal tool for the treatment of the delicate periocular region where even minimal scarring can result in ocular complications.

Responding in configural discrimination problems depends on density of reinforcement in time.

Previous research has shown that conditioned responding in differential skin conductance conditioning increased for reinforced stimuli (CSs+) but remained constant for nonreinforced stimuli (CSs-) due to decreasing reinforcement density. The present two experiments (Experiment 1: Negative patterning; Experiment 2: Positive patterning) were designed to disentangle a possible confound of reinforcement density with stimulus frequency. In order to achieve this, we varied the intertrial interval (18 s, 24 s, or 48 s) and held constant the numbers of CSs+ and of CSs- in each of both discrimination problems. With increasing intertrial intervals, we found higher responding both to CSs+ and to CSs- as well as increased response differentiation. We discuss these results with respect to two mechanisms offered by Wagner's SOP model and conclude that the observed effects are due to variations in density of reinforcement in time.

Effects of stimulus probability on pupillary dilation and reaction time in categorization.

Stimuli presented with a low frequency elicit larger pupillary responses than those presented with a high frequency. Similar effects are known for motor responses observed in reaction time experiments. Utilizing this stimulus probability effect, we conducted a Go/NoGo reaction time experiment and measured pupillary dilation to evaluate categorization. We found no probability effect when participants used distinctive features to classify stimuli with different frequencies into the same category. If no distinctive features could be applied, however, the effect was observed in both pupillary and reaction time data. The stimulus probability effect can serve as a tool for the evaluation of categorization and is discussed in the context of orienting.

Tracking stimulus processing in Pavlovian pupillary conditioning.

The aim of the present study was to evaluate whether the anticipatory pupillary dilation response is a useful indicator for the examination of complex differential conditioning problems like patterning. A human fear conditioning procedure with six groups (n=20 each) was used to examine conditioned stimulus (CS) processing when a compound stimulus was reinforced, but not its elements (positive patterning) or when the elements were reinforced, but not the compound (negative patterning), as well as modifications in which the compound was replaced by either a new compound or by a new element. We found evidence for conditioning within 2 s after CS onset. Group differences in differential conditioning indicated systematic differences in CS processing due to different discrimination task difficulties. This study showed that the pupil response is a suitable indicator for human Pavlovian conditioning with high time resolution within and between trials.

Cellular immunotherapy after autologous hematopoietic stem cell transplantation: experimental strategies and clinical experiences.

Recurrence of disease after autologous hematopoietic stem cell transplantation is at least partly due to contamination of the reinfused transplant with tumor cells, thereby limiting the clinical outcome after transplantation. On the other hand, immunological effector cells are capable of purging bone marrow transplants in vitro and of destroying disseminated tumor cells in vivo. Cellular immunotherapy subsequent to autologous stem cell transplantation is therefore expected to have a major impact on recurrence rates of the disease. In this review, we present various strategies utilizing immunologic effector cells for elimination of disseminated tumor cells and discuss the advantages and limitations of cellular immunotherapy after autologous hematopoietic stem cell transplantation.

Evidence for the utilization of distinctive features in nonlinear discrimination problems.

There is evidence that in human Pavlovian conditioning positive patterning (A-, B-, AB+) as well as negative patterning (A+, B+, AB-) are solved by applying abstract rules. In the present report we further investigated how humans solve patterning discriminations by conducting two Go/NoGo reaction time experiments that utilized the stimulus probability effect: stimuli presented with a low probability of occurrence elicit larger pupil dilations than those presented with a high frequency. In decreasing the ratio of compound and elemental trials from 1/1 (24 A, 24 B, 48 AB) in Experiment 1 to 1/2 (32 A, 32 B, 32 AB) in Experiment 2 we manipulated stimulus probability. The results of both experiments indicate that humans utilize distinctive features such as number information in order to classify the stimuli.

The impact of reinforcement density on response differentiation in configural discrimination problems.

Two human Pavlovian conditioning experiments investigated the impact of reinforcement density (the number of reinforced trials divided by the total number of trials) on discrimination learning. Experiment 1 used a negative patterning problem (A+, B+, AB-) and Experiment 2 used a positive patterning problem (A-, B-, AB+). In both experiments, reinforcement density varied across four levels. Response differentiation between reinforced and non-reinforced stimuli was linearly related to the decrease in reinforcement density. Responses to nonreinforced stimuli did not differ between the four groups in either experiment. In contrast to this, responses to reinforced stimuli were considerably more pronounced in conditions with lower reinforcement density. For negative patterning, this replicates and extends similar observations from other species. For positive patterning, this is a finding that has not yet been reported in other experiments. The results are in agreement with the comparator hypothesis (Miller & Matzel, 1988) and with Wagner's (1981) "standard operating procedures" (SOP) model.

The effect of stimulus probability on pupillary response as an indicator of cognitive processing in human learning and categorization.

Stimuli presented with a low probability of occurrence elicit larger pupillary dilations than those presented with a high frequency. Utilizing this stimulus probability effect, we conducted two Go/NoGo reaction time experiments to analyze category learning and compound coding in the context of associative learning. Experiment 1 showed no stimulus probability effect when participants used an abstract rule to classify stimuli with different probabilities into the same category. When no rules could be applied, however, the stimulus probability effect was observed. Hence, this effect can be utilized to identify the application of rules in category learning. Experiment 2 demonstrated that the stimulus probability effect can also be used in determining whether compounds are processed in terms of elemental stimuli or as new entities. The results of Experiment 2 supported elemental rather than configural processing. Obviously, the probability effect can be used as a tool for the evaluation of categorization and compound processing.

Are rules applied in Pavlovian electrodermal conditioning with humans general or outcome specific?

There is growing evidence that in human skin conductance response (SCR) conditioning positive patterning (A-, B-, AB+) and negative pattering (A+, B+, AB-) are solved by applying two different rules. The present experiments investigated whether the representations of such rules are specific or general with regard to outcomes and response systems. In Experiment 1, we investigated SCR and eyelid conditioning with different types of training administered in an interleaved fashion. We found that positive patterning SCR conditioning interfered with negative patterning SCR conditioning, whereas eyeblink conditioning had no effect on SCR conditioning. In Experiment 2, in which eyeblink and SCR conditioning were administered in sequential fashion, the same result was obtained. We conclude that the rules involved in solving patterning tasks might be specific to outcomes and/or response systems.

Differential conditioning of anticipatory pupillary dilation responses in humans.

The purpose of the present experiments was to demonstrate conditioning of anticipatory pupillary dilation responses in humans as previous efforts to condition pupillary dilation had yielded inconsistent results. In those studies, using an aversive unconditioned stimulus (US) had yielded more promising results than using non-aversive USs. In three experiments we utilized a reaction time task as a non-aversive US and observed reliable differential conditioning of anticipatory pupillary dilation. Differential responding was evident within very few trials and was largest late in the anticipatory interval. Experiment 4 replicated these findings using an aversive US (electric shock). In measuring anticipatory responses in a differential conditioning preparation all four experiments provided clear evidence for Pavlovian conditioning of pupillary dilation in humans.