The random transitions of ion channels between conducting and nonconducting states generate a source internal fluctuations in neuron, known as channel noise. standard method for modeling the nonlinearly couples continuous-time Markov chains to differential equation voltage. Beginning with work R. F. Fox Y.-N. Lu [Phys. Rev. E 49, 3421 (1994)], there have been attempts simpler models that use stochastic (SDEs) approximate spiking activity produced by chain models. Recent numerical...

The ongoing activity of neurons generates a spatially and time-varying field extracellular voltage (Ve). This Ve reflects population-level neural activity, but does it modulate dynamics the function circuits? We provide cable theory framework to study how bundle model this feeds back influences membrane potential (Vm). find that these "ephaptic interactions" are small not negligible. population can generate with millivolt-scale amplitude, perturbs Vm "nearby" cables effectively increases...

Locomotion generates adventitious sounds which enable detection and localization of predators prey. Such contain brisk changes or transients in amplitude. We investigated the hypothesis that ill-understood temporal specializations binaural circuits subserve lateralization such sound transients, based on different time arrival at ears (interaural differences, ITDs). find Lateral Superior Olive (LSO) neurons show exquisite ITD-sensitivity, reflecting extreme precision reliability excitatory...

Model-based studies of responses auditory nerve fibers to electrical stimulation can provide insight into the functioning cochlear implants. Ideally, these identify limitations in sound processing strategies and lead improved methods for providing information implant users. To accomplish this, models must accurately describe spiking activity while avoiding excessive complexity that would preclude large-scale simulations populations obscure mechanisms influence neural encoding information. In...

Local field potentials are important indicators of in vivo neural activity. Sustained, phase-locked, sound-evoked extracellular fields the mammalian auditory brainstem, known as neurophonic, reflect activity neurons medial superior olive (MSO). We develop a biophysically based model neurophonic that accounts for features recordings cat brainstem. By making plausible idealizations regarding spatial symmetry MSO and temporal synchrony their afferent inputs, we reduce challenging problem...

Extracellular voltage recordings ( V e ; field potentials) provide an accessible view of in vivo neural activity, but proper interpretation potentials is a long-standing challenge. Computational modeling can aid identifying generators potentials. In the auditory brainstem cats, spatial patterns sound-evoked resemble, strikingly, generated by current dipoles. Previously, we developed biophysically-based model binaural nucleus, medial superior olive (MSO), that accounts qualitatively for...

Coincidence detector neurons transmit timing information by responding preferentially to concurrent synaptic inputs. Principal cells of the medial superior olive (MSO) in mammalian auditory brainstem are superb coincidence detectors. They encode sound source location with high temporal precision, distinguishing submillisecond differences among We investigate computationally how dynamic coupling between input region (soma and dendrite) spike-generating output (axon axon initial segment) can...

Understanding the consumption needs of retirees is critical to assessing adequacy retirement income and possible impact Social Security reform on well-being older Americans. This study uses data from Health Retirement Study, including a recent supplemental expenditure survey, analyze spending patterns for adults ages 65 older. Results indicate that typical married spend 84 percent after-tax household income, nonmarried 92 income. Even at individuals devote larger share their expenditures...

Purpose: Retirees in traditional pension plans must generally choose between single life annuities, which provide regular payments until death, and joint survivor pay less each month but continue to make the spouse after death of retired worker. This article examines payout decision measures share married retirees with annuities who forego protection. Design Methods: The analysis consists a probit model decision, based on data from 1992–2000 waves Health Retirement Study. Results: More than...

Neurons process and convey information by transforming barrages of synaptic inputs into spiking activity. Synaptic inhibition typically suppresses the output firing activity a neuron, is commonly classified as having subtractive or divisive effect on neuron's Subtractive can narrow range that evoke eliminating responses to non-preferred inputs. Divisive form gain control: it modifies rates while preserving Since these two "modes" have distinct impacts neural coding, important understand...

Employment rates for single mothers with dependent children have risen steadily in recent years, due part to welfare reform and expansions the Earned Income Tax Credit. This paper examines this increase analyzes implications future retirement security. The results show that increases employment earnings during late 1990s will translate into modestly higher Social Security benefits better outcomes when they reach later life, assuming these trends persist. Despite improvement, however, most...

This project uses dynamic microanalytic simulation techniques to explore the distributional consequences of Plan 2 President's Commission Strengthen Social Security. plan includes a voluntary personal account that would be carved out currently-scheduled benefit contributions, new minimum benefit, and an increase in widow(er)s benefits. It also shifts current wage-indexed initial formula price-indexed address most system's long-term solvency problem. The analysis begins by adopting...

with a production error in the denominator second line of Eq. ( 21).The 21) should read as "μ chan (1μ )".The equation has been corrected 14 April 2011.

Abstract Synaptic and neural properties can change during periods of auditory deprivation. These changes may disrupt the computations that neurons perform. In brainstem chickens, deprivation lead to in size biophysics axon initial segment (AIS) sound source localization circuit. This is phenomenon plasticity. Individuals who use cochlear implants (CIs) experience hearing loss, so we ask whether AIS plasticity medial superior olive (MSO), a key stage location processing, would impact time...

Neural adaptation in sensory systems can potentially improve the efficiency and fidelity of neural encoding (e.g. [1]). In auditory system, for instance, firing rates peripheral midbrain neurons shift to better represent range most likely stimulus levels [2,3]. Adaptation has long been known exist throughout system response acoustic stimulation, now studies have revealed that nerve exhibits rate electric stimulation [4]. Adaptation may, therefore, important implications function design...

Illusions give intriguing insights into perceptual and neural dynamics. In the auditory continuity illusion, two brief tones separated by a silent gap may be heard as one continuous tone if noise burst with appropriate characteristics fills gap. This illusion probes conditions under which listeners link related sounds across time maintain in face of sudden changes sound mixtures. Conceptual explanations this have been proposed, but its basis is still being investigated. work we provide...

The ongoing activity of neurons generates a spatially- and time-varying field extracellular voltage ($V_e$). This $V_e$ reflects population-level neural activity, but does it modulate dynamics the function circuits? We provide cable theory framework to study how bundle model this feeds back influences membrane potential ($V_m$). find that these "ephaptic interactions" are small not negligible. population can generate with millivolt-scale amplitude perturbs $V_m$ "nearby" cables effectively...