Two experiments, both presenting diotic, harmonic tone complexes (100 Hz fundamental), were conducted to explore the envelope-related component of the frequency-following response (FFR ENV ), a measure of synchronous, subcortical neural activity evoked by a periodic acoustic input. Experiment 1 directly compared two common analysis methods, computing the magnitude spectrum and the phase-locking value (PLV). Bootstrapping identified which FFR ENV frequency components were statistically above the noise floor for each metric and quantified the statistical power of the approaches. Across listeners and conditions, the two methods produced highly correlated results. However, PLV analysis required fewer processing stages to produce readily interpretable results. Moreover, at the fundamental frequency of the input, PLVs were farther above the metric's noise floor than spectral magnitudes. Having established the advantages of PLV analysis, the efficacy of the approach was further demonstrated by investigating how different acoustic frequencies contribute to FFR ENV , analyzing responses to complex tones composed of different acoustic harmonics of 100 Hz (Experiment 2). Results show that the FFR ENV response is dominated by peripheral auditory channels responding to unresolved harmonics, although low-frequency channels driven by resolved harmonics also contribute. These results demonstrate the utility of the PLV for quantifying the strength of FFR ENV across conditions.

The Eph family of receptors is the largest family of RTKs. Eph receptors are stimulated by a family of membrane-linked ligands designated ephrins (6, 7). Both biochemical and genetic studies have established the central role that ephrins have in the control of cell contact repulsion, boundary formation, cell migration, and repulsive axon guidance (6). Repulsive axon guidance appears to be caused by modulation of cytoskeletal organization leading to regulation of neural growth-cone development (8). Eph-receptors also regulate cell-matrix interaction and cell proliferation by affecting signaling by integrins (9-11) and by modulation of MAPK response (12)(13)(14).In this article, we demonstrate that EphA4 binds directly and specifically via the N-terminal portion of its protein tyrosine kinase core to the juxtamembrane (JM) region of FGFRs. In cells that express EphA4 and FGFRs, the interactions between the cytoplasmic domains of EphA4 and FGFRs can lead to transreceptor activation, resulting in tyrosine phosphorylation of FRS2␣ and MAPK activation. The synergistic effect of ephrin-A1 stimulation on FGF2-induced cellular responses may influence the biological outcome of the activation of these two families of RTKs. Materials and MethodsYeast Two-Hybrid Experiments. The yeast two-hybrid system was used as described (15). The bait used for screening was 81 aa (amino acids 398-478), derived from the JM domain of human FGFR3. A human brain cDNA library in a pJG4-5 vector consisting of 3.5 ϫ 10 6 primary transformants (Clontech) was used for screening for proteins that interact with the JM domain of FGFR3. Fig. 1A shows the constructs used to detect interactions between the cytoplasmic domain of EphA4 and the JM domain of FGFR3.Cells. HEK293 cells were maintained in DMEM supplemented with 10% calf serum. For neural differentiation, P19 cells were maintained in ␣-MEM supplemented with 10% FBS containing 0.5 M retinoic acid for 3 days. Rat L6 myoblasts were maintained in DMEM supplemented with 10% FBS.Preparation of Ephrin-A1. Ephrin-A1 fused to human IgG-Fc was purchased from Sigma-Aldrich. Before application to the cells, 5 g of ephrin-A1-Fc was oligomerized by mixing with 12 g of rabbit anti-human IgG-Fc (Jackson ImmunoResearch) in 1 ml of PBS at 4°C for at least 1 h. As a control, a human IgG-Fc fragment (Jackson ImmunoResearch) was also applied after oligomerization.Expression Plasmids. Full-length cDNA of human EphA4 was prepared by RT-PCR using total RNA from a human brain extract (Clontech) as the template. The cDNA of human FGFR4 was prepared by RT-PCR using K562 cell-derived RNA as the template. The cDNAs for FGFR1 and FGFR2 were provided by W. McKeehan (Texas A&M University, College Station, TX). The cDNA for FGFR3 was provided by D. E. Johnson (University of Pittsburgh, Pittsburgh). Receptor mutants were prepared by applyConflict of interest statement: No conflicts declared.

Eosinophil infiltration, a hallmark of allergic asthma, is essential for type 2 immune responses. How the initial eosinophil recruitment is regulated by lung dendritic cell (DC) subsets during the memory stage after allergen challenge is unclear. Here, we show that the initial eosinophil infiltration is dependent on lung cDC1s, which require nitric oxide (NO) produced by inducible NO synthase from lung CD24−CD11b+ DC2s for inducing CCL17 and CCL22 to attract eosinophils. During late phase responses after allergen challenge, lung CD24+ cDC2s inhibit eosinophil recruitment through secretion of TGF-β1, which impairs the expression of CCL17 and CCL22. Our data suggest that different lung antigen-presenting cells modulate lung cDC1-mediated eosinophil recruitment dynamically, through secreting distinct soluble factors during the memory stage of chronic asthma after allergen challenge in the mouse.

Cells of the neural stem cell lineage in the adult subventricular zone (SVZ) respond to brain insult by increasing their numbers and migrating through the rostral migratory stream. However, in most areas of the brain other than the SVZ and the subgranular zone of the dentate gyrus, such a regenerative response is extremely weak. Even these two neurogenic regions do not show extensive regenerative responses to repair tissue damage, suggesting the presence of an intrinsic inhibitory microenvironment (niche) for stem cells. In the present study, we assessed the effects of injection of clustered ephrin-A1-Fc into the lateral ventricle of rats with unilateral nigrostriatal dopamine depletion. Ephrin-A1-Fc clustered by anti-IgG(Fc) antibody was injected stereotaxically into the ipsilateral lateral ventricle of rats with unilateral nigrostriatal lesions induced by 6-hydroxydopamine, and histologic analysis and behavioral tests were performed. Clustered ephrin-A1-Fc transformed the subventricular niche, increasing bromodeoxyuridine-positive cells in the subventricular area, and the cells then migrated to the striatum and differentiated to dopaminergic neurons and astrocytes. In addition, clustered ephrin-A1-Fc enhanced angiogenesis in the striatum on the injected side. Along with histologic improvements, behavioral derangement improved dramatically. These findings indicate that the subventricular niche possesses a mechanism for regulating both stem cell and angiogenic responses via an EphA–mediated signal. We conclude that activation of EphA receptor–mediated signaling by clustered ephrin-A1-Fc from within the lateral ventricle could potentially be utilized in the treatment of neurodegenerative diseases such as Parkinson's disease.