Inferences Training Affects Memory, Rumination, and Mood

Making negative inferences for negative events, ruminating about them, and retrieving negative aspects of memories have all been associated with depression. However, the causal mechanisms that link negative inferences to negative mood and the interplay between inferences, rumination, and memory have not been explored. In the current study, we used a cognitive-bias modification (CBM) procedure to train causal inferences and assessed training effects on ruminative thinking, memory, and negative mood among people with varying levels of depression. Training had immediate effects on negative mood and rumination but not after recall of a negative autobiographical memory. Note that training affected memory: Participants falsely recalled inferences presented during the training in a training-congruent manner. Moreover, among participants with high levels of depression, training also affected causal inferences they made for an autobiographical memory retrieved after training. Our findings shed light on negative cognitive cycles that may contribute to depression

Comparable Ages for the Independent Origins of Electrogenesis in African and South American Weakly Electric Fishes

One of the most remarkable examples of convergent evolution among vertebrates is illustrated by the independent origins of an active electric sense in South American and African weakly electric fishes, the Gymnotiformes and Mormyroidea, respectively. These groups independently evolved similar complex systems for object localization and communication via the generation and reception of weak electric fields. While good estimates of divergence times are critical to understanding the temporal context for the evolution and diversification of these two groups, their respective ages have been difficult to estimate due to the absence of an informative fossil record, use of strict molecular clock models in previous studies, and/or incomplete taxonomic sampling. Here, we examine the timing of the origins of the Gymnotiformes and the Mormyroidea using complete mitogenome sequences and a parametric Bayesian method for divergence time reconstruction. Under two different fossil-based calibration methods, we estimated similar ages for the independent origins of the Mormyroidea and Gymnotiformes. Our absolute estimates for the origins of these groups either slightly postdate, or just predate, the final separation of Africa and South America by continental drift. The most recent common ancestor of the Mormyroidea and Gymnotiformes was found to be a non-electrogenic basal teleost living more than 85 millions years earlier. For both electric fish lineages, we also estimated similar intervals (16–19 or 22–26 million years, depending on calibration method) between the appearance of electroreception and the origin of myogenic electric organs, providing rough upper estimates for the time periods during which these complex electric organs evolved de novo from skeletal muscle precursors. The fact that the Gymnotiformes and Mormyroidea are of similar age enhances the comparative value of the weakly electric fish system for investigating pathways to evolutionary novelty, as well as the influences of key innovations in communication on the process of species radiation

Chronic Exposure to Low Frequency Noise at Moderate Levels Causes Impaired Balance in Mice

We are routinely exposed to low frequency noise (LFN; below 0.5 kHz) at moderate levels of 60–70 dB sound pressure level (SPL) generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans. However, there is limited information about the influence of chronic exposure to LFN at moderate levels for balance. In this study, we investigated whether chronic exposure to LFN at a moderate level of 70 dB SPL affects the vestibule, which is one of the organs responsible for balance in mice. Wild-type ICR mice were exposed for 1 month to LFN (0.1 kHz) and high frequency noise (HFN; 16 kHz) at 70 dB SPL at a distance of approximately 10–20 cm. Behavior analyses including rotarod, beam-crossing and footprint analyses showed impairments of balance in LFN-exposed mice but not in non-exposed mice or HFN-exposed mice. Immunohistochemical analysis showed a decreased number of vestibular hair cells and increased levels of oxidative stress in LFN-exposed mice compared to those in non-exposed mice. Our results suggest that chronic exposure to LFN at moderate levels causes impaired balance involving morphological impairments of the vestibule with enhanced levels of oxidative stress. Thus, the results of this study indicate the importance of considering the risk of chronic exposure to LFN at a moderate level for imbalance

Parallel Evolution of Auditory Genes for Echolocation in Bats and Toothed Whales

The ability of bats and toothed whales to echolocate is a remarkable case of convergent evolution. Previous genetic studies have documented parallel evolution of nucleotide sequences in Prestin and KCNQ4, both of which are associated with voltage motility during the cochlear amplification of signals. Echolocation involves complex mechanisms. The most important factors include cochlear amplification, nerve transmission, and signal re-coding. Herein, we screen three genes that play different roles in this auditory system. Cadherin 23 (Cdh23) and its ligand, protocadherin 15 (Pcdh15), are essential for bundling motility in the sensory hair. Otoferlin (Otof) responds to nerve signal transmission in the auditory inner hair cell. Signals of parallel evolution occur in all three genes in the three groups of echolocators—two groups of bats (Yangochiroptera and Rhinolophoidea) plus the dolphin. Significant signals of positive selection also occur in Cdh23 in the Rhinolophoidea and dolphin, and Pcdh15 in Yangochiroptera. In addition, adult echolocating bats have higher levels of Otof expression in the auditory cortex than do their embryos and non-echolocation bats. Cdh23 and Pcdh15 encode the upper and lower parts of tip-links, and both genes show signals of convergent evolution and positive selection in echolocators, implying that they may co-evolve to optimize cochlear amplification. Convergent evolution and expression patterns of Otof suggest the potential role of nerve and brain in echolocation. Our synthesis of gene sequence and gene expression analyses reveals that positive selection, parallel evolution, and perhaps co-evolution and gene expression affect multiple hearing genes that play different roles in audition, including voltage and bundle motility in cochlear amplification, nerve transmission, and brain function

Toward a Multifaceted Heuristic of Digital Reading to Inform Assessment, Research, Practice, and Policy

In this commentary, the author explores the tension between almost 30 years of work that has embraced increasingly complex conceptions of digital reading and recent studies that risk oversimplifying digital reading as a singular entity analogous with reading text on a screen. The author begins by tracing a line of theoretical and empirical work that both informs and complicates our understanding of digital literacy and, more specifically, digital reading. Then, a heuristic is proposed to systematically organize, label, and define a multifaceted set of increasingly complex terms, concepts, and practices that characterize the spectrum of digital reading experiences. Research that informs this heuristic is used to illustrate how more precision in defining digital reading can promote greater clarity across research methods and advance a more systematic study of promising digital reading practices. Finally, the author discusses implications for assessment, research, practice, and policy

Supplementary Material for: South American Weakly Electric Fish (Gymnotiformes) Are Long-Wavelength-Sensitive Cone Monochromats

Losses of cone opsin genes are noted in animals that are nocturnal or rely on senses other than vision. We investigated the cone opsin repertoire of night-active South American weakly electric fish. We obtained opsin gene sequences from genomic DNA of 3 gymnotiforms <i>(Eigenmannia virescens, Sternopygus macrurus, Apteronotus albifrons)</i> and the assembled genome of the electric eel <i>(Electrophorus electricus)</i>. We identified genes for long-wavelength-sensitive (LWS) and medium-wavelength-sensitive cone opsins (RH2) and rod opsins (RH1). Neither of the 2 short-wavelength-sensitive cone opsin genes were found and are presumed lost. The fact that <i>Electrophorus</i> has a complete repertoire of extraretinal opsin genes and conservation of synteny with the zebrafish <i>(Danio rerio)</i> for genes flanking the 2 short-wavelength-sensitive opsin genes supports the supposition of gene loss. With microspectrophotometry and electroretinograms we observed absorption spectra consistent with RH1 and LWS but not RH2 opsins in the retinal photoreceptors of <i>E. virescens. </i>This profile of opsin genes and their retinal expression is identical to the gymnotiform's sister group, the catfish, which are also nocturnally active and bear ampullary electroreceptors, suggesting that this pattern likely occurred in the common ancestor of gymnotiforms and catfish. Finally, we noted an unusual N-terminal motif lacking a conserved glycosylation consensus site in the RH2 opsin of gymnotiforms, a catfish and a characin <i>(Astyanax mexicanus)</i>. Mutations at this site influence rhodopsin trafficking in mammalian photoreceptors and cause retinitis pigmentosa. We speculate that this unusual N terminus may be related to the absence of the RH2 opsin in the cones of gymnotiforms and catfish