Assessing the validity of subjective reports in the auditory streaming paradigm

Here, we tested three possible biasing effects on perceptual reports in the auditory streaming paradigm: errors due to imperfect understanding of the instructions, voluntary perceptual biasing, and susceptibility to implicit expectations. 1) Analysis of the responses to catch trials separately promoting each of the possible percepts allowed us to exclude participants who likely have not fully understood the instructions. 2) Explicit biasing instructions led to markedly different behavior than the conventional neutral-instruction condition, suggesting that listeners did not voluntarily bias their perception in a systematic way under the neutral instructions. Comparison with a random response condition further supported this conclusion. 3) No significant relationship was found between social desirability, a scale-based measure of susceptibility to implicit social expectations, and any of the perceptual measures extracted from the subjective reports. This suggests that listeners did not significantly bias their perceptual reports due to possible implicit expectations present in the experimental context. In sum, these results suggest that valid perceptual data can be obtained from subjective reports in the auditory streaming paradigm

PDE approximation of large systems of differential equations

A large system of ordinary differential equations is approximated by a parabolic partial differential equation with dynamic boundary condition and a different one with Robin boundary condition. Using the theory of differential operators with Wentzell boundary conditions and similar theories, we give estimates on the order of approximation. The theory is demonstrated on a voter model where the Fourier method applied to the PDE is of great advantage.Comment: reviewer requests incorporated, to appear in "Operators and Matrices

Auditory multistability and neurotransmitter concentrations in the human brain

Multistability in perception is a powerful tool for investigating sensory–perceptual transformations, because it produces dissociations between sensory inputs and subjective experience. Spontaneous switching between different perceptual objects occurs during prolonged listening to a sound sequence of tone triplets or repeated words (termed auditory streaming and verbal transformations, respectively). We used these examples of auditory multistability to examine to what extent neurochemical and cognitive factors influence the observed idiosyncratic patterns of switching between perceptual objects. The concentrations of glutamate–glutamine (Glx) and γ-aminobutyric acid (GABA) in brain regions were measured by magnetic resonance spectroscopy, while personality traits and executive functions were assessed using questionnaires and response inhibition tasks. Idiosyncratic patterns of perceptual switching in the two multistable stimulus configurations were identified using a multidimensional scaling (MDS) analysis. Intriguingly, although switching patterns within each individual differed between auditory streaming and verbal transformations, similar MDS dimensions were extracted separately from the two datasets. Individual switching patterns were significantly correlated with Glx and GABA concentrations in auditory cortex and inferior frontal cortex but not with the personality traits and executive functions. Our results suggest that auditory perceptual organization depends on the balance between neural excitation and inhibition in different brain regions. This article is part of the themed issue ‘Auditory and visual scene analysis'

Fényérzékeny molekulák és fotoreceptorok a gerincesek retinájában és tobozmirigyében = Photosensitive molecules and photoreceptors in the vertebrate retina and pineal gland

Míg az emlősök legtöbbjében, amelyekben legalább kétféle színérzékenységű fotoreceptor található, kimutatható a transzdifferenciáció, vagyis a rövidhullám-érzékeny (kék) csapok korai megjelenése, és ezek egy részében a középhullám-érzékeny (zöld) pigment későbbi expressziója. Az eredeti kék pigment eltűnése eredményezi a definitív zöld csapokat, míg azok, amelyekben a zöld pigment egyáltalán nem jelenik meg, adják a kék csap-populációt. Elvetettük a hipotézist, hogy a monokromatikus fajokan is a kék-pigment expresszióján keresztül vezet az út. Felnőttben is előfordulnak két pigmentet tartalmazó csapok. A transzdifferenciáció (csap-fejlődés) nem áll meg újszülött korban, hanem folytatódik felnőttben is. Ezek idegi őssejtek, amelyek a retina regenerációjában játszhatnak szerepet (anti-PCNA). A csapok differenciálódásában közrejátszó tényezők közül a BDNF, az NT-3 és a TrkB szerepet játszanak a kék-zöld átalakulásban. Tenyésztés és immuncitokémia bizonyítja, hogy a kék csapok fejlődéséhez elegendő a megfelelő feltételek fennállása. A zöld csapok megjelenéséhez azonban az említett tényezők is szükségesek. A nem-vizuális fotoreceptorok feladata a diurnális ritmus beállítása. A bennük lévő cryptochromok kék-érzékenyek. Az ékszakai megvilágítás patológiás hatásait (emlőrák, colorectalis tumorok, stb.) a pineális melatonin gátlása okozza. Ezek redukálhatók kék fény-mentes megvilágítással, azaz megfelelő színszűrők használatával. | In mammals that possess two color-specific photoreceptors, transdifferentiation is present. That means the early appearance of short wave (blue) cones and the later expression of middle wave (green) pigment in some of them. The disappearance of the original blue pigment results in the development of definitive green cones. Those in which no green pigment appears at all will make the blue cone population. The hypothesis that in monochromatic species green cones come about through the transitory appearance of blue pigment has been rejected. Dual cones expressing two visual pigments occur also in adults. Obviously, the transdifferentiation does not come to an end in the early postnatal period, rather it goes on in the adulthood. These might be neuronal stem cells playing a role in the regeneration of the retina (anti-PCNA). Of the factors having a role in the cone differentiation, BDNF, NT-3 and TrkB seem to be effective in the blue-green transition. Immunocytochemistry and tissue culture prove that proper culture technique is enough for the development of blue cones, however the above factors are indispensable for the green cones. Non-visual photoreceptors play a role in the entrainment of the diurnal clock. Their cryptochromes proved to be blue-sensitive. The pathologic effects of night work are attributed to the inhibition of pineal melatonin. The adverse reactions might be reduced with blue light-free illumination, with proper color filters

Mean-field approximation of counting processes from a differential equation perspective

Deterministic limit of a class of continuous time Markov chains is considered based purely on differential equation techniques. Starting from the linear system of master equations, ordinary differential equations for the moments and a partial differential equation, called Fokker–Planck equation, for the distribution is derived. Introducing closures at the level of the second and third moments, mean-field approximations are introduced. The accuracy of the mean-field approximations and the Fokker–Planck equation is investigated by using two differential equation-based and an operator semigroup-based approach