The Effect of Outcome Probability on Generalization in Predictive Learning

Author(s):  
Hadar Ram ◽  
Dieter Struyf ◽  
Bram Vervliet ◽  
Gal Menahem ◽  
Nira Liberman

Abstract. People apply what they learn from experience not only to the experienced stimuli, but also to novel stimuli. But what determines how widely people generalize what they have learned? Using a predictive learning paradigm, we examined the hypothesis that a low (vs. high) probability of an outcome following a predicting stimulus would widen generalization. In three experiments, participants learned which stimulus predicted an outcome (S+) and which stimulus did not (S−) and then indicated how much they expected the outcome after each of eight novel stimuli ranging in perceptual similarity to S+ and S−. The stimuli were rings of different sizes and the outcome was a picture of a lightning bolt. As hypothesized, a lower probability of the outcome widened generalization. That is, novel stimuli that were similar to S+ (but not to S−) produced expectations for the outcome that were as high as those associated with S+.

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1230
Author(s):  
Araceli Posadas-Mondragón ◽  
José Leopoldo Aguilar-Faisal ◽  
Gerardo Zuñiga ◽  
Jonathan Javier Magaña ◽  
José Angel Santiago-Cruz ◽  
...  

Dengue manifestations range from a mild form, dengue fever (DF), to more severe forms such as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). The ability of the host to present one of these clinical forms could be related to polymorphisms located in genes of the Toll-like receptors (TLRs) which activate the pro-inflammatory response. Therefore, the genotyping of single nucleotide genetic polymorphisms (SNPs) in TLR3 (rs3775291 and rs6552950), TLR4 (rs2737190, rs10759932, rs4986790, rs4986791, rs11536865, and rs10983755), TLR7 (rs179008 and rs3853839), and TLR8 (rs3764880, rs5741883, rs4830805, and rs1548731) was carried out in non-genetically related DHF patients, DF patients, and general population (GP) subjects. The SNPs were analyzed by real-time PCR by genotyping assays from Applied Biosystems®. The codominance model showed that dengue patients had a lower probability of presenting the TLR4-rs2737190-G/G genotype (odds ratio (OR) (95% CI) = 0.34 (0.14–0.8), p = 0.038). Dengue patients showed a lower probability of presenting TLR4-rs11536865-G/C genotype (OR (95% CI) = 0.19 (0.05–0.73), p = 0.0092) and had a high probability of presenting the TACG haplotype, but lower probability of presenting the TGCG haplotype in the TLR4 compared to GP individuals (OR (95% CI) = 0.55 (0.35–0.86), p = 0.0084). In conclusion, the TLR4-rs2737190-G/G and TLR4-rs11536865-G/C genotypes and TGCG haplotype were associated with protection from dengue.


Author(s):  
Dieter Struyf ◽  
Carlos Iberico ◽  
Bram Vervliet

The peak of learned responding normally occurs at the learning stimulus itself, but can shift to a different stimulus after discriminative learning. This provides important information about the nature of the generalization mechanism, and reveals alternative pathways through which learned responses can increase. Over two experiments, we established the peak-shift effect in a human predictive learning paradigm. Participants were asked to predict the occurrence of a neutral outcome (drawing of a lightning bolt) based on preceding geometrical figures (rings of different sizes). During learning, the middle-sized ring was sometimes followed by the outcome, whereas a larger ring was never followed by the outcome. At test, we presented larger and smaller rings (Experiment 1), or only a slightly smaller ring (Experiment 2). We consistently observed highest prediction of the outcome to the slightly smaller ring. Predictive estimations in humans can reach their height to stimuli that have never actually participated in the learning experiences. We argue that the results are most in line with an associative learning account, rather than an adaptation-level or a rule-learning account.


Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Eleonora Savio-Galimberti ◽  
Joshua I Goldhaber ◽  
John H Bridge

We tested the hypothesis that sarcoplasmic reticulum (SR) Ca release triggered by cardiac action potentials is significantly affected by Na influx through brain isoforms of the Na channel. These channels are reportedly located in the t-tubules and could therefore activate reverse Na-Ca exchanger (NCX) and contribute to triggered release. In the complete absence of a Na gradient (Li replacement) Ca transients evoked by action potentials were delayed, their upstrokes slowed and their peak values diminished (SR Ca content not depleted under these conditions). Ca spikes recorded under these conditions occurred at significantly lower probability and became asynchronous (see figure ). Tetrodotoxin 200 nM (this concentration selectively blocks brain Na channel isoforms Nav 1.1, 1.3 and 1.6) reduced the magnitude and rate of rise of Ca transients in a way that resembled the effect of removing the Na gradient. We suggest that early activation of brain type Na channels leads to elevation of Na in the dyadic cleft. This causes reverse NCX, which primes the junction with Ca before L-type Ca channels (LCC) have opened. Since the junction has been primed with Ca, short LCC openings can effectively gate ryanodine receptors (RyRs). Because these LCC openings have short latencies and occur with high probability they produce spikes with short latencies at high probability. In the absence of a Na gradient longer LCC openings are required to fill the junction and gate RyRs. These occur with lower probability and greater latency. We conclude that brain Na channels together with NCX significantly increase LCC-RyR coupling fidelity and synchronize spikes.


1989 ◽  
Vol 16 (3) ◽  
pp. 289 ◽  
Author(s):  
CP Catterall ◽  
RJ Green ◽  
DN Jones

Habitat use by birds in suburbs of Brisbane, Queensland was studied during winter, at sites with relatively similar habitat features near to (0.25-0.5km) and far from (2-3km) a eucalypt forest. Variation in other factors was restricted. Distance from native forest was found to have little influence on abundance of birds in suburban habitats. House sparrows and willie wagtails were relatively more abundant at the far sites. Most of the more common forest-dwelling species were not common in either near or far suburbs. There was little similarity in relative abundance of bird species between the forest and either the near or far suburbs. A similarity in species diversity and positive correlations in species abundance between near and far sites indicate that most species are either forest or suburb 'specialists'. Native birds were more selective in their choice of plant category than introduced birds, and had a high probability of using certain native and exotic plant species, and a lower probability of using others. Although generally more abundant, introduced birds did not have a high probability of using any plant genus or type. Birds in the area studied are probably altering their patterns of habitat use in response to changes in food availability.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 1832-1832
Author(s):  
Meletios A. Dimopoulos ◽  
Efstathios Kastritis ◽  
Maria Roussou ◽  
Erasmia Psimenou ◽  
Maria Gavriatopoulou ◽  
...  

Abstract Severe renal failure (RF) is a common complication of symptomatic myeloma and in approximately 1-5% of newly diagnosed patients, dialysis may be required. Severe RF is associated with significant morbidity and mortality; these patients are often excluded from clinical trials. Bortezomib/dexamethasone (VD) based regimens have been proposed as the backbone of the treatment of newly diagnosed MM patients who present with severe RF. In addition to VD-based regimens other means are also under investigation, mainly for patients who require dialysis. Such options include high cut-off hemodialysis combined with effective antimyeloma therapy based on VD. In the current analysis, we focused on the outcomes of patients with severe RF and of those requiring dialysis in order to evaluate the activity of VD-based combinations. Our study included 78 (39M/39F) consecutive patients with severe RF (eGFR <30 ml/min/1.73 m2 per the MDRD formula); 27 (35%) patients required dialysis. All these patients were treated in a single center (Alexandra Hospital, University of Athens, Greece), they received similar supportive care and started bortezomib-based therapy upon diagnosis. IMWG renal response criteria were used: renal complete response (CRrenal) was defined as a sustained increase of baseline eGFR to >60 ml/min/1.73 m2, renal partial response (PRrenal) as an increase of eGFR from <15 to 30-50 ml/min/1.73 m2 and renal minor response (MRrenal) as a sustained improvement of baseline eGFR of <15 ml/min/1.73 m2 to 15-29 ml/min/1.73 m2 or if baseline eGFR was 15-29 ml/min/1.73 m2, improvement to 30-59 ml/min/1.73 m2. The median age was 66 years (range: 37-88) and 27% were >75 years. The median eGFR was 11 ml/min/1.73 m2 (range: 1- 29 ml/min/1.73 m2); 65% had eGFR<15 ml/min/1.73 m2. The median age of patients who required dialysis was 66 years (range 37-88) and all these patients received dialysis with regular filters. Median level of proteinuria was 1.5 g/24h (range 0.2-12 g/24h) and of involved free light chain (iFLC) was 8,455 mg/l (range 44-201,000 mg/l). All patients received VD-based regimens: 22 (28%) received VD, while 56 (72%) received a triplet [33 (42%) VCD, 15 (19%) VTD, 6 (7%) PAD and 2 (2%) VMP). Among patients requiring dialysis, 70% received a triplet (10 VCD, 8 VTD and one PAD). At least MRrenal was recorded in 52 (67%) patients within a median of 23 days (range 4-238). CRrenal was documented in 36% of patients and PRrenal in 12% (major renal response rate of 48%). The median time to major renal response was 28 days (range 7-238 days). Fourteen of 27 (51%) patients became dialysis independent; the median time to dialysis independence was 140 days (range 11-474). Three-drug combinations vs VD alone were associated with higher probability of renal responses (72% vs 30%; p=0.006). Among patients who became dialysis independent 5 received VTD, 1 PAD, 5 VCD and 3 VD. A triplet was associated with higher probability of dialysis discontinuation (58% vs 35% for VD). ROC analysis indicated that iFLC ≥11,550 mg/L was associated with a lower probability of major renal response (14% vs 59%, p=0.002) and longer time to major renal response (>240 to 66 days, p=0.017). In patients requiring dialysis iFLC ≥11,550 mg/L was also associated with lower probability of dialysis discontinuation (37.5% vs 56%) and longer time to dialysis discontinuation (474 vs 93 days). Other factors associated with major renal response in univariate analysis were age <65 years (p=0.004) and myeloma response (p=0.001). Among patients requiring dialysis, age <65 years (p=0.072), male gender (p=0.037) and myeloma response (p=0.037) were associated with a higher probability of dialysis discontinuation. Early death (<2 months from treatment initiation) occurred in 9 (12%) patients. The median survival for all patients was 44 months. Excluding early deaths, the survival of patients who became dialysis-independent was longer than that of patients who remained on dialysis (90 vs 28 months, p=0.015). Our study suggests that three drug VD-based combinations are associated with a high probability of renal response and a >50% probability of dialysis discontinuation in MM patients requiring dialysis, without the use of high cut-off filters. Furthermore, patients who became dialysis independent have better overall survival. The levels of FLCs are predictive of the probability and of the time required for renal response, including dialysis independence. Disclosures Dimopoulos: Celgene: Honoraria; Onyx: Honoraria; Janssen: Honoraria; Genesis: Honoraria; Janssen-Cilag: Honoraria; Amgen: Honoraria; Novartis: Honoraria. Terpos:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel expenses; Celgene: Honoraria, Other: travel expenses; Novartis: Honoraria.


2002 ◽  
Vol 7 (3) ◽  
pp. 4-5

Abstract Different jurisdictions use the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) for different purposes, and this article reviews a specific jurisdictional definition in the Province of Ontario of catastrophic impairment that incorporates the AMA Guides. In Ontario, a whole person impairment (WPI) exceeding 54% or a mental or behavioral impairment of Class 4 or 5 qualifies the individual for catastrophic benefits, and individuals who do not meet the test receive a lesser benefit. By inference, this establishes a parity threshold among dissimilar injuries and dissimilar outcome assessment scales for benefits. In Ontario, the Glasgow Coma Scale (GCS) identifies patients who have a high probability of death or of severely disabled survival. The GCS recognizes gradations of vegetative state and disability, but translating the gradations for rating individual impairment on ordinal scales into a method of assessing percentage impairments cannot be done reliably, as explained in the AMA Guides, Fifth Edition. The AMA Guides also notes that mental and behavioral impairment in Class 4 (marked impairment) or 5 (extreme impairment) indicates “catastrophic impairment” by significantly impeding useful functioning (Class 4) or significantly impeding useful functioning and implying complete dependency on another person for care (Class 5). Translating the AMA Guides guidelines into ordinal scales cannot be done reliably.


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