Characterization of the development of the high-acuity area of the chick retina.

The fovea is a small region within the central retina that is responsible for our high acuity daylight vision. Chickens also have a high acuity area (HAA), and are one of the few species that enables studies of the mechanisms of HAA development, due to accessible embryonic tissue and methods to readily perturb gene expression. To enable such studies, we characterized the development of the chick HAA using single molecule fluorescent in situ hybridization (smFISH), along with more classical methods. We found that Fgf8 provides a molecular marker for the HAA throughout development and into adult stages, allowing studies of the cellular composition of this area over time. The radial dimension of the ganglion cell layer (GCL) was seen to be the greatest at the HAA throughout development, beginning during the period of neurogenesis, suggesting that genesis, rather than cell death, creates a higher level of retinal ganglion cells (RGCs) in this area. In contrast, the HAA acquired its characteristic high density of cone photoreceptors post-hatching, which is well after the period of neurogenesis. We also confirmed that rod photoreceptors are not present in the HAA. Analyses of cell death in the developing photoreceptor layer, where rods would reside, did not show apoptotic cells, suggesting that lack of genesis, rather than death, created the "rod-free zone" (RFZ). Quantification of each cone photoreceptor subtype showed an ordered mosaic of most cone subtypes. The changes in cellular densities and cell subtypes between the developing and mature HAA provide some answers to the overarching strategy used by the retina to create this area and provide a framework for future studies of the mechanisms underlying its formation.

High temporal frequency light response in mouse retina is mediated by ON and OFF bipolar cells and requires FAT3 signaling.

Vision is initiated by the reception of light by photoreceptors and subsequent processing via parallel retinal circuits. Proper circuit organization depends on the multi-functional tissue polarity protein FAT3, which is required for amacrine cell connectivity and retinal lamination. Here we investigated the retinal function of Fat3 mutant mice and found decreases in physiological and perceptual responses to high frequency flashes. These defects did not correlate with abnormal amacrine cell wiring, pointing instead to a role in bipolar cell subtypes that also express FAT3. Indeed, similar deficits were observed in mice lacking the bipolar cell glutamate receptors GRIK1 (OFF-bipolar cells) and GRM6 (ON-bipolar cells). Mechanistically, FAT3 binds to the synaptic protein PTPσ and is required to localize GRIK1 to OFF-cone bipolar cell synapses with cone photoreceptors. How FAT3 impacts ON-cone bipolar cell function at high temporal frequency remains to be uncovered. These findings expand the repertoire of FAT3's functions and reveal the importance of both ON- and OFF-bipolar cells for high frequency light response.

Effects of Music Therapy on Quality of Life in Adults with Sickle Cell Disease (MUSIQOLS): A Mixed Methods Feasibility Study.

PURPOSE: To investigate the feasibility, acceptability, and preliminary efficacy of a 6-session music therapy protocol on self-efficacy, quality of life, and coping skills in adults with sickle cell disease (SCD). PATIENTS AND METHODS: Using a mixed-methods intervention design, adults with SCD (ages 21-57; mean age 32.33) were randomized (1:1) to either 1) a 6-session music therapy (MT) intervention (n = 12) or 2) waitlist control (WLC) (n = 12) using stratified randomization where factors were age in years (≤30 vs >30), and sex (male, female). All participants completed two weeks of daily electronic pain diary entries and self-efficacy, quality of life, and coping skills measures before and after their assigned study condition to explore preliminary efficacy. MT participants were taught music exercises accessed via smartphone and subsequently interviewed to determine feasibility and acceptability. RESULTS: The enrollment rate was 89%. All study measures were completed, with high rates of electronic pain diary completion at baseline (70%) and 2-week follow-up (66%). Interviews revealed two overall themes related to MT participants' experience: 1) participants learned new self-management skills and 2) MT improved participants' ability to cope with pain. MT participants demonstrated 100% attendance. In preliminary analyses, MT participants demonstrated significant improvements (means ± SD) in self-efficacy (5.42 ± 5.43, p = 0.008, d = 1.20), PROMIS sleep disturbance (-1.49 ± 6.68, p = 0.023, d = -0.99), PROMIS pain interference (-2.10 ± 4.68, p = 0.016, d = -1.06), and ASCQ-Me social functioning impact scores (2.97 ± 6.91, p = 0.018, d = 1.05) compared to WLC participants. CONCLUSION: Preliminary findings support the feasibility and acceptability of music therapy for home use in adults with SCD. While music therapy may assist adults with SCD in improving self-efficacy and quality of life, subsequent, fully-powered clinical research is needed to determine its efficacy.

Synaptic Diversity Suppresses Complex Collective Behavior in Networks of Theta Neurons.

Comprehending how the brain functions requires an understanding of the dynamics of neuronal assemblies. Previous work used a mean-field reduction method to determine the collective dynamics of a large heterogeneous network of uniformly and globally coupled theta neurons, which are a canonical formulation of Type I neurons. However, in modeling neuronal networks, it is unreasonable to assume that the coupling strength between every pair of neurons is identical. The goal in the present work is to analytically examine the collective macroscopic behavior of a network of theta neurons that is more realistic in that it includes heterogeneity in the coupling strength as well as in neuronal excitability. We consider the occurrence of dynamical structures that give rise to complicated dynamics via bifurcations of macroscopic collective quantities, concentrating on two biophysically relevant cases: (1) predominantly excitable neurons with mostly excitatory connections, and (2) predominantly spiking neurons with inhibitory connections. We find that increasing the synaptic diversity moves these dynamical structures to distant extremes of parameter space, leaving simple collective equilibrium states in the physiologically relevant region. We also study the node vs. focus nature of stable macroscopic equilibrium solutions and discuss our results in the context of recent literature.