Tactile experience shapes prey-capture behavior in Etruscan shrews

A crucial role of tactile experience for the maturation of neural response properties in the somatosensory system is well established, but little is known about the role of tactile experience in the development of tactile behaviors. Here we study how tactile experience affects prey capture behavior in Etruscan shrews, Suncus etruscus. Prey capture in adult shrews is a high-speed behavior that relies on precise attacks guided by tactile Gestalt cues. We studied the role of tactile experience by three different approaches. First, we analyzed the hunting skills of young shrews' right after weaning. We found that prey capture in young animals in most, but not all, aspects is similar to that of adults. Second, we performed whisker trimming for 3–4 weeks after birth. Such deprivation resulted in a lasting disruption of prey capture even after whisker re-growth: attacks lacked precise targeting and had a lower success rate. Third, we presented adult shrews with an entirely novel prey species, the giant cockroach. The shape of this roach is very different from the shrew's normal (cricket) prey and the thorax—the preferred point of attack in crickets—is protected by a heavy cuticle. Initially shrews attacked giant roaches the same way they attack crickets and targeted the thoracic region. With progressive experience, however, shrews adopted a new attack strategy targeting legs and underside of the roaches while avoiding other body parts. Speed and efficiency of attacks improved. These data suggest that tactile experience shapes prey capture behavior

Kin-Avoidance in Cannibalistic Homicide

Cannibalism in the animal kingdom is widespread and well characterized, whereas the occurrence of human cannibalism has been controversial. Evidence points to cannibalism in aboriginal societies, prehistory, and the closely related chimpanzees. We assembled a non-comprehensive list (121 offenders, ~631 victims) of cannibalistic homicides in modern societies (since 1900) through internet-searches, publications, and expert questioning. Cannibalistic homicides were exceedingly rare, and often sex-related. Cannibalistic offenders were mainly men and older than offenders of non-cannibalistic homicides, whereas victims were comparatively young. Cannibalistic offenders typically killed manually (stabbing, strangulating, and beating) rather than using a gun. Furthermore, they killed more strangers and fewer intimates than conventional offenders. Human cannibals, similar to cannibalism in other species, killed and ate conspecifics, occasionally vomited and only rarely (2.5% of victims) ate kin. Interestingly, cannibalistic offenders who killed their blood relatives had more severe mental problems than non-kin-cannibals. We conclude that cannibalistic homicides have a unique pattern of murder methods, offenders, and victims

Bright Integrated Photon-Pair Source for Practical Passive Decoy-State Quantum Key Distribution

We report on a bright, nondegenerate type-I parametric down-conversion source, which is well suited for passive decoy-state quantum key distribution. We show the photon-number-resolved analysis over a broad range of pump powers and we prove heralded higher-order $n$-photon states up to $n=4$. The inferred photon click statistics exhibit excellent agreements to the theoretical predictions. From our measurement results we conclude that our source meets the requirements to avert photon-number-splitting attacks.Comment: 5 pages, 4 figure

Active Touch During Shrew Prey Capture

Although somatosensation in multiple whisker systems has been studied in considerable detail, relatively little information is available regarding whisker usage and movement patterns during natural behaviors. The Etruscan shrew, one of the smallest mammals, relies heavily on its whisker system to detect and kill its highly mobile insect prey. Here, we tracked whisker and body motion during prey capture. We found that shrews made periodic whisker movements (whisking) with frequencies ranging from 12 to 17 Hz. We compared shrew and rat whisking and found that shrew whisking was smaller amplitude and higher frequency than rat whisking, but that the shrew and rat whisking cycle were similar in that the velocity was higher during retraction than protraction. We were able to identify four phases during the shrew hunting behavior: (i) an immobile phase often preceding hunting, (ii) a search phase upon the initiation of hunting, (iii) a contact phase defined by whisker-to-cricket contact, and (iv) an attack phase, characterized by a rapid head movement directed toward the cricket. During the searching phase, whisking was generally rhythmic and whiskers were protracted forward. After prey contact, whisking amplitude decreased and became more variable. The final strike was associated with an abrupt head movement toward the prey with high head acceleration. Prey capture proceeded extremely fast and we obtained evidence that shrews can initiate corrective maneuvers with a minimal latency <30 ms. While the shrew's rostrum is straight and elongated during most behaviors, we show for the first time that shrews bend their rostrum during the final strike and grip their prey with a parrot beak shaped snout

Annealing-Induced Changes in the Nature of Point Defects in Sublimation-Grown Cubic Silicon Carbide

In recent years, cubic silicon carbide (3C-SiC) has gained increasing interest as semiconductor material for energy saving and optoelectronic applications, such as intermediate-band solar cells, photoelectrochemical water splitting, and quantum key distribution, just to name a few. All these applications critically depend on further understanding of defect behavior at the atomic level and the possibility to actively control distinct defects. In this work, dopants as well as intrinsic defects were introduced into the 3C-SiC material in situ during sublimation growth. A series of isochronal temperature treatments were performed in order to investigate the temperature-dependent annealing behavior of point defects. The material was analyzed by temperature-dependent photoluminescence (PL) measurements. In our study, we found a variation in the overall PL intensity which can be considered as an indication of annealing-induced changes in structure, composition or concentration of point defects. Moreover, a number of dopant-related as well as intrinsic defects were identified. Among these defects, there were strong indications for the presence of the negatively charged nitrogen vacancy complex (NC–VSi)−, which is considered a promising candidate for spin qubits

Structure, function, and cortical representation of the rat submandibular whisker trident

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Neuroscience 33 (2013): 4815-4824, doi:10.1523/JNEUROSCI.4770-12.2013.Although the neurobiology of rodent facial whiskers has been studied intensively, little is known about sensing in other vibrissae. Here we describe the under-investigated submandibular “whisker trident” on the rat's chin. In this three-whisker array, a unique unpaired midline whisker is laterally flanked by two slightly shorter whiskers. All three whiskers point to the ground and are curved backwards. Unlike other whiskers, the trident is not located on an exposed body part. Trident vibrissae are not whisked and do not touch anything over long stretches of time. However, trident whiskers engage in sustained ground contact during head-down running while the animal is exploring or foraging. In biomechanical experiments, trident whiskers follow caudal ground movement more smoothly than facial whiskers. Remarkably, deflection angles decrease with increasing ground velocity. We identified one putative trident barrel in the left somatosensory cortex and two barrels in the right somatosensory cortex. The elongated putative trident-midline barrel is the longest and largest whisker barrel, suggesting that the midline trident whisker is of great functional significance. Cortical postsynaptic air-puff responses in the trident representation show much less temporal precision than facial whisker responses. Trident whiskers do not provide as much high-resolution information about object contacts as facial whiskers. Instead, our observations suggest an idiothetic function: their biomechanics allow trident whiskers to derive continuous measurements about ego motion from ground contacts. The midline position offers unique advantages in sensing heading direction in a laterally symmetric manner. The changes in trident deflection angle with velocity suggest that trident whiskers might function as a tactile speedometer.This work was supported by the Marine Biological Laboratory, the National Institute of Mental Health (Training Grant 5R25MH059472), Humboldt Universita¨t zu Berlin, the Bernstein Center for Computational Neuroscience Berlin, the German Federal Ministry of Education and Research (Fo¨rderkennzeichen 01GQ1001A), the Deutsche Forschungsgemeinschaft (EXC 257, Neurocure), and the European Research Council (grant to M.B.). M.L.W. was supported by a National Research Service Award from National Institute of Neurological Disorders and Stroke (1F31NS077847).2013-09-1

Revealing the radiative and non-radiative relaxation rates of the fluorescent dye Atto488 in a λ/2 Fabry-Pérot-resonator by spectral and time resolved measurements

Using a Fabry-Pérot-microresonator with controllable cavity lengths in the λ/2-regime, we show the controlled modification of the vibronic relaxation dynamics of a fluorescent dye molecule in the spectral and time domain. By altering the photonic mode density around the fluorophores we are able to shape the fluorescence spectrum and enhance specifically the probability of the radiative transitions from the electronic excited state to distinct vibronic excited states of the electronic ground state. Analysis and correlation of the spectral and time resolved measurements by a theoretical model and a global fitting procedure allows us to reveal quantitatively the spectrally distributed radiative and non-radiative relaxation dynamics of the respective dye molecule under ambient conditions at the ensemble level

Coevolution of rostrum and brain in pig species

Domestic pigs have a prominent cortical gyrus (the rostrum gyrus) isomorphic to the contralateral hemirostrum. It is unclear, however, if the size and shape of the rostrum gyrus are of evolutionary/functional relevance. Here, we address this question by assessing the relationship of rostrum and rostrum gyrus across eight pig species. To this end, we quantified rostrum morphology in fresh and alcohol-preserved pig specimens by surface scans, microfocus computed tomography scans, and photography. We establish that the size and shape of the rostrum gyrus can be precisely inferred from endocasts. We then took advantage of the accessibility of pig skulls and endocasts to assess features of the rostrum gyrus across species. Our investigation led to the following results: (i) The rostra of pig species show basic similarities. (ii) A cortical rostrum gyrus is apparent in all pigs. (iii) The size of the rostrum gyrus differs across species and outgroups of the evolutionary dominant suinae (i.e., peccaries and the babirusa) have a noticeably smaller rostrum gyrus. (iv) Warthogs have a derived rostrum morphology with an extra fold and a very wide rostrum; the warthog rostrum gyrus recapitulates these rostrum features. (v) Domestic pigs have relatively smaller rostrum gyrus than wild boars. We also provide indications for a conserved cytoarchitectonic patterning of the rostrum gyrus. We conclude that the rostrum gyrus is a neural module that was putatively present in the common ancestor of pigs and that this neural module is conserved across pig species. Natural selection maintains the rostrum gyrus’ size and its exact isomorphism to the rostrum.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Humboldt‐Universität zu Berlin http://dx.doi.org/10.13039/501100006211Peer Reviewe