Better safe than sorry: Risky function exploitation through safe optimization

Exploration-exploitation of functions, that is learning and optimizing a mapping between inputs and expected outputs, is ubiquitous to many real world situations. These situations sometimes require us to avoid certain outcomes at all cost, for example because they are poisonous, harmful, or otherwise dangerous. We test participants' behavior in scenarios in which they have to find the optimum of a function while at the same time avoid outputs below a certain threshold. In two experiments, we find that Safe-Optimization, a Gaussian Process-based exploration-exploitation algorithm, describes participants' behavior well and that participants seem to care firstly whether a point is safe and then try to pick the optimal point from all such safe points. This means that their trade-off between exploration and exploitation can be seen as an intelligent, approximate, and homeostasis-driven strategy.Comment: 6 pages, submitted to Cognitive Science Conferenc

A linear model for event-related respiration responses

AbstractBackgroundCognitive processes influence respiratory physiology. This may allow inferring cognitive states from measured respiration. Here, we take a first step towards this goal and investigate whether event-related respiratory responses can be identified, and whether they are accessible to a model-based approach.New methodWe regard respiratory responses as the output of a linear time invariant system that receives brief inputs after psychological events. We derive average responses to visual targets, aversive stimulation, and viewing of arousing pictures, in interpolated respiration period (RP), respiration amplitude (RA), and respiratory flow rate (RFR). We then base a Psychophysiological Model (PsPM) on these averaged event-related responses. The PsPM is inverted to yield estimates of cognitive input into the respiratory system. This method is validated in an independent data set.ResultsAll three measures show event-related responses, which are captured as non-zero response amplitudes in the PsPM. Amplitude estimates for RA and RFR distinguish between picture viewing and the other tasks. This pattern is replicated in the validation experiment.Comparison with existing methodsExisting respiratory measures are based on relatively short time-intervals after an event while the new method is based on the entire duration of respiratory responses.ConclusionOur findings suggest that interpolated respiratory measures show replicable event-related response patterns. PsPM inversion is a suitable approach to analysing these patterns, with a potential to infer cognitive processes from respiration

Analytic measures for quantification of arousal from spontaneous skin conductance fluctuations

AbstractAutonomic arousal is often indexed by spontaneous fluctuations in skin conductance. Here, we derive a simple measure of sympathetic arousal, using a convolution model of how sudomotor bursting causes fluctuations in skin conductivity. Under this model, the time-integral of measured conductance is proportional to the frequency and amplitude of sudomotor bursts. We demonstrate the validity of this measure in relation to finite impulse response models, and show that it is a better predictor of autonomic arousal, relative to conventional measures

PENGARUH PEMBERIAN EKSTRAK DAUN KENDAL(Cordia dichotoma)SEBAGAI PESTISIDA NABATI PENGENDALI HAMA Spodoptera litura F PADA TANAMAN SAWI CAISIM (Brassica juncea (L.))

Penelitian ini bertujuan untuk mengetahui pengaruh perlakuan preventif dan kuratif pemberian ekstrak daun kendal (Cordia dichotoma) terhadap persentase mortalitas larva Spodoptera litura F, persentase pupa Spodoptera litura F, tingkat kerusakan tanaman sawi caisim (Brassica juncea (L.)), dosis ekstrak daun kendal(Cordia dichtoma) yang berpengaruh optimal sebagai pengendali hama Spodoptera Litura F.Jenis Penelitian ini adalah Rancangan Penelitian Eksperimen dengan 2 perlakuan yaitu preventif dan kuratif, 5 variasi dosis dan 5 kali pengulangan. Objek penelitian ini adalah 250 ekor larva instar III Spodoptera litura F yang diperoleh dari perkebunan tanaman sawi caisim di jl.Ketep,Ketep,Sawangan, Magelang,Jawa Tengah. Ekstrak daun kendal (Cordia dichotoma) dibuat dari 1000 gram daun kendal segar yang dicampur dengan 10 ml alkohol 95% dan 1000 ml air dan didiamkan selama 24 jam. Starter ekstrak daun kendal diencerkan menjadi 5 variasi dosis yaitu 0%, 10%, 20%, 25% dan pestisida sintetik. Penginfeksian hama dilakukan pada tanaman sawi yang berumur 21 hari setelah tanam yang ditanam di green house FMIPA UNY. Hama diinfeksikan pada tanaman sawi masing-masing 5 ekor larva Spodoptera litura F. Hasil uji statistik Oneway Anova pada pengamatan pertama dan ke dua pada perlakuan kuratif diperoleh p=0,00<0,005, dan pada pengamatan ke dua dan ke tiga perlakuan preventif diperoleh p=0,18 dan p=0,000<0,005 artinya terdapat perbedaan yang nyata ekstrak daun kendal (Cordia dichotoma) terhadap mortalitas larva Spodoptera litura F. Hasil uji statistik Oneway Anova pada pengamatan ke dua pada perlakuan kuratif yaitu 0,01 dan pada pengamatan ke tiga perlakuan preventif diperoleh p=0,000<0,05 artinya terdapat perbedaan yang nyata ekstrak daun kendal (Cordia dichotoma) terhadap persentase pupa Spodoptera litura F. Pemberian ekstrak daun kendal (Cordia dichotoma) memberikan pengaruh terhadap tingkat kerusakan tanaman sawi caisim. Ekstrak daun kendal (Cordia dichotoma) pada dosis 25% merupakan dosis efektif mengakibatkan kematian larva di atas 80%

Asymmetric representation of aversive prediction errors in Pavlovian threat conditioning

Learning to predict threat is important for survival. Such learning may be driven by differences between expected and encountered outcomes, termed prediction errors (PEs). While PEs are crucial for reward learning, the role of putative PE signals in aversive learning is less clear. Here, we used functional magnetic resonance imaging in humans to investigate neural PE signals. Four cues, each with a different probability of being followed by an aversive outcome, were presented multiple times. We found that neural activity only at omission - but not at occurrence - of predicted threat related to PEs in the medial prefrontal cortex. More expected omission was associated with higher neural activity. In no brain region did neural activity fulfill necessary computational criteria for full signed PE representation. Our result suggests that, different from reward learning, aversive learning may not be primarily driven by PE signals in one single brain region

Threat memory reminder under matrix metalloproteinase 9 inhibitor doxycycline globally reduces subsequent memory plasticity

Associative memory can be rendered malleable by a reminder. Blocking the ensuing re-consolidation process is suggested as a therapeutic target for unwanted aversive memories. Matrix metalloproteinase (MMP)-9 is required for structural synapse remodelling involved in memory consolidation. Inhibiting MMP-9 with doxycycline is suggested to attenuate human threat conditioning. Here, we investigate whether MMP-9 inhibition also interferes with threat memory re-consolidation. N=78 male and female human participants learned the association between two visual conditioned stimuli (CS+) and a 50% chance of an unconditioned nociceptive stimulus (US), and between CS- and the absence of US. On day 7, one CS+ was reminded without reinforcement 3.5 hours after ingesting either 200 mg doxycycline, or placebo. On day 14, retention of CS memory was assessed under extinction, by fear-potentiated startle. Contrary to our expectations, we observed a greater CS+/CS- difference in participants who were reminded under doxycycline, compared to placebo. Participants who were reminded under placebo showed extinction learning during the retention test, which was not observed in the doxycycline group. There was no difference between the reminded and the non-reminded CS+ in either group. In contrast, during re-learning after the retention test, CS+/CS- difference was more pronounced in the placebo than the doxycycline group. To summarize, a single dose of doxycycline appeared to have no specific impact on re-consolidation, but to globally impair extinction learning, and threat re-learning, after drug clearance.MMP-9 inhibition appears to attenuate memory consolidation. It could also be a target for blocking reconsolidation. Here, we test this hypothesis in human threat conditioning. We find that doxycycline has no specific impact on a reminded cue, but confers a global reduction in extinction learning and threat learning beyond the clearance of the drug. This may point towards a more long-lasting impact of doxycycline treatment on memory plasticity

Effect of the Matrix Metalloproteinase Inhibitor Doxycycline on Human Trace Fear Memory

Learning to predict threat is of adaptive importance, but aversive memory can also become disadvantageous and burdensome in clinical conditions such as posttraumatic stress disorder (PTSD). Pavlovian fear conditioning is a laboratory model of aversive memory and thought to rely on structural synaptic reconfiguration involving matrix metalloproteinase (MMP)9 signaling. It has recently been suggested that the MMP9-inhibiting antibiotic doxycycline, applied before acquisition training in humans, reduces fear memory retention after one week. This previous study used cued delay fear conditioning, in which predictors and outcomes overlap in time. However, temporal separation of predictors and outcomes is common in clinical conditions. Learning the association of temporally separated events requires a partly different neural circuitry, for which the role of MMP9 signaling is not yet known. Here, we investigate the impact of doxycycline on long-interval (15 s) trace fear conditioning in a randomized controlled trial with 101 (50 females) human participants. We find no impact of the drug in our preregistered analyses. Exploratorypost hocanalyses of memory retention suggested a serum level-dependent effect of doxycycline on trace fear memory retention. However, effect size to distinguish CS+/CS− in the placebo group turned out to be smaller than in previously used delay fear conditioning protocols, which limits the power of statistical tests. Our results suggest that doxycycline effect on trace fear conditioning in healthy individuals is smaller and less robust than anticipated, potentially limiting its clinical application potential

Predictors of risky foraging behaviour in healthy young people

During adolescence and early adulthood, learning when to avoid threats and when to pursue rewards becomes crucial. Using a risky foraging task, we investigated individual differences in this dynamic across 781 individuals aged 14-24 years who were split into a hypothesis-generating discovery sample and a hold-out confirmation sample. Sex was the most important predictor of cautious behaviour and performance. Males earned one standard deviation (or 20%) more reward than females, collected more reward when there was little to lose and reduced foraging to the same level as females when potential losses became high. Other independent predictors of cautiousness and performance were self-reported daringness, IQ and self-reported cognitive complexity. We found no evidence for an impact of age or maturation. Thus, maleness, a high IQ or self-reported cognitive complexity, and self-reported daringness predicted greater success in risky foraging, possibly due to better exploitation of low-risk opportunities in high-risk environments

Prazosin during threat discrimination boosts memory of the safe stimulus

The α-1 adrenoreceptor antagonist prazosin has shown promise in the treatment of post-traumatic stress disorder (PTSD) symptoms, but its mechanisms are not well understood. Here we administered prazosin or placebo prior to threat conditioning (day 1) and tested subsequent extinction (day 2) and reextinction (day 3) in healthy human participants. Prazosin did not affect threat conditioning but augmented stimulus discrimination during extinction and reextinction, via lower responding to the safe stimulus. These results suggest that prazosin during threat acquisition may have influenced encoding or consolidation of safety processing in particular, subsequently leading to enhanced discrimination between the safe and threatening stimuli