Observation of others’ threat reactions recovers memories previously shaped by firsthand experiences

Information about dangers can spread effectively by observation of others’ threat responses. Yet, it is unclear if such observational threat information interacts with associative memories that are shaped by the individual’s direct, firsthand experiences. Here, we show in humans and rats that the mere observation of a conspecific’s threat reactions reinstates previously learned and extinguished threat responses in the observer. In two experiments, human participants displayed elevated physiological responses to threat-conditioned cues after observational reinstatement in a context-specific manner. The elevation of physiological responses (arousal) was further specific to the context that was observed as dangerous. An analogous experiment in rats provided converging results by demonstrating reinstatement of defensive behavior after observing another rat’s threat reactions. Taken together, our findings provide cross-species evidence that observation of others’ threat reactions can recover associations previously shaped by direct, firsthand aversive experiences. Our study offers a perspective on how retrieval of threat memories draws from associative mechanisms that might underlie both observations of others’ and firsthand experiences.

Evidence for Magnetoreception in Red Drum (Sciaenops ocellatus), Black Drum (Pogonias cromis), and Sea Catfish (Ariopsis felis)

<p>Over the past few decades, magnetoreception has been discovered in several species of teleost and elasmobranch fishes by employing varied experimental methods including conditioning experiments, observations of alignment with external fields, and experiments with magnetic deterrents. Biogenic magnetite has been confirmed to be an important receptor mechanism in some species, but there is ongoing debate regarding whether other mechanisms are at work. This paper presents evidence for magnetoreception in three additional species, red drum (<em>Sciaenops</em><em> ocellatus</em>), black drum (<em>Pogonias</em><em> </em><em>cromis</em>), and sea catfish (<em>Ariopsis</em><em> </em><em>felis</em>), by employing experiments to test whether fish respond differently to bait on a magnetic hook than on a control. In red drum, the control hook outcaught the magnetic hook by 32-18 for Χ²=3.92 and a <em>P</em>-value of 0.048. Black drum showed a significant attraction for the magnetic hook, which prevailed over the control hook by 11-3 for Χ²=4.57 and a <em>P</em>-value of 0.033. Gafftopsail catfish (<em>Bagre</em><em> marinus</em>) showed no preference with a 31-35 split between magnetic hook and control for Χ²=0.242 and a <em>P</em>-value of 0.623. In a sample of 100 sea catfish in an analogous experiment using smaller hooks, the control hook was preferred 62-38 for Χ²=5.76 and a <em>P</em>-value of &lt; 0.001. Such a simple method for identifying magnetoreceptive species may quickly expand the number of known magnetoreceptive species and allow for easier access to magnetoreceptive species and thus facilitate testing of magnetoreceptive hypotheses.</p>

Transport of Heap Formed by Granular Materials on an Inclined Surface

We study experimentally the transport of heap formed by granular materials vertically vibrated on an inclined surface. A relationship is presented of how the velocity of heap changing with driving acceleration and frequency. The shape of the heap bottom is measured by detecting the colliding phase of the heap bottom with plane. An analogous experiment is performed with a heap shape block of Plexiglas. The mechanism for transport of the heap is presented.

Why so much oestriol? A comparison of the aromatisation of androstenedione and 16α-hydroxyandrostenedione when incubated alone or together with human placental microsomes

Estimates of the relative abundance of 16α-hydroxy- and 16-deoxyoestrogens in late pregnancy urine lie between 13:1 and 5:1, yet the ratio of the concentrations of the major precursors 16α-hydroxydehydroepiandrosterone sulphate and dehydroepiandrosterone sulphate in cord blood is about 2·5:1. This discrepancy might imply that 16α-hydroxy-C19 steroids are used more efficiently for placental oestrogen biosynthesis than are the 16α-deoxy-C19 steroids. On testing this hypothesis by incubation of placental microsomes with 16α-hydroxy- and 16-deoxy- precursors together (concentration ratios 128:1 to 1:1), initial rates of oestrogen formation were highest from the 16-deoxy-C19 steroid. Additionally, whilst each substrate appeared to inhibit the aromatisation of the other, the 16-deoxy-C19 steroid was the more potent inhibitor. These findings were supported by an analogous experiment with placental slices. When each precursor was examined separately with microsomes from 4 placentae, aromatisation of the 16α-hydroxy-C19 steroid (Michaelis constant, (Km) 0·75–1·24 μmol/l, maximum reaction velocity (Vmax) 28–69 pmol product/min/mg protein) was less efficient than that of the 16-deoxy-C19 steroid (Km 0·10–0·15 μmol/l, Vmax 71–145 pmol product/min/mg protein). To reconcile the disparity between the measured utilisation of precursors in vitro and expectations drawn from precursor availability and urinary excretion rates, sources of urinary 16α-hydroxyoestrogens additional to placental aromatisation need to be considered. Hydroxylation of 16-deoxyoestrogens (the phenolic pathway) appears limited but aromatisation in fetal liver of 16α-hydroxyandrostenedione not utilised by the placenta appears to be worth attention. Journal of Endocrinology (1996) 148, 399–407

Decomposition of peroxobenzoic acid in benzene catalyzed by transition metal 2,4-pentanedionates

The decomposition of peroxobenzoic acid in benzene was studied, and catalytic effects of Fe(III), Mn(III), Co(II), Co(III), and Cr(III) on the reaction rate and the composition of the reaction mixture were investigated. An analogous experiment carried out in perdeuterobenzene and determination of the distribution of deuterium in the reaction products provided evidence for the participation of the solvent in peroxobenzoic acid decomposition.

V. Researches on the colouring matters derived from coal-tar.—No. IV. Phenyltolylamine

The discovery of diphenylamine among the products of decomposition furnished by the destructive distillation of aniline-blue (triphenylic rosaniline) which I have lately communicated to the Royal Society (Proceedings, June 16, 1864), naturally suggested the investigation of analogously constituted bodies in a similar direction. My attention has in the first place been directed to the study of a compound which, from its mode of formation, ought to be designated as toluidine-blue. When a salt of rosaniline (the acetate for instance) is heated with double its weight of toluidine, phenomena present themselves which are similar to those observed in the analogous experiment with aniline. In the course of a few hours the rosaniline passes through all the different shades of violet, and is ultimately converted into a dark lustrous mass, which dissolves in alcohol with a deep indigo-blue colour. This substance is the acetate of tritolylrosaniline. By treatment with alcoholic ammonia, and subsequently addition of water to the solution, the free base is easily obtained, from which the several salts may be prepared by the usual processes. I have examined only one of these salts, viz. the hydrochlorate. Repeatedly crystallized from boiling alcohol, this salt is obtained in small blue crystals insoluble in water, which at 100° C. contain C 41 H 38 N 3 Cl = C 20 H 16 (C 7 H 7 ) 3 } N 3 , HCl .