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PubMed1977

Increased intracellular sodium mimics some but not all aspects of photoreceptor adaptation in the ventral eye of Limulus.

The effects of the intracellular iontophoretic injection of Na+ ions have been quantitatively compared with adaptation in ventral photoreceptors of Limulus. We find that: (a) both light adaptation and sodium injection are associated with a decrease in the variability of the threshold response amplitued; (b) both light adaptation and sodium injection are associated with a decrease in the absolute value of the temporal dispersion of the threshold response time delay; (c) the same template curve adequately fits the intensity response relationships measured under light adaptation and Na+ injection; (d) both light adaptation and Na+ injection produce a fourfold decrease in response time delay for a desensitization of 3 log units; (e) the time coures of light adaptation and dark adaptation is significantly faster than the onset of and recovery from desensitization produced by Na+ injection; (f) unlike local illumination, Na+ injection does not produce localized desensitization of the photoreceptor. These findings suggest that a rise in intracellular Na+ concentration makes at most only a minor contribution (probably less than 5%) to the total adaptation of these receptors in the intensity range we have examined (up to 3 log units above absolute threshold). However, changes in intracellular Na+ concentration may contribute to certain components of light and dark adaptation in these receptors.

Action Potentials↗
PubMed1979

[A report on studies on the child's adaptation to school and family environment after neoplastic disease].

The objective of this study was to learn the course of child's adaptation process to school and family environment following the neoplastic disease. The study also aimed select the environment and personality factors influencing adaptation effect. The study pertains to the child's personality and how it works at home and at school. It also tries to get to know the child's environment. 65 children of different social environment were studied. Motor functions of these children were limited as the result of tumour disease. Special scale of adaptation was prepared when the research was over. By means of this sale two groups of children were distinguished: those who were well adapted to the environment and those who were not. Statistical analysis was used to compare the groups on account of the following factors: health factors including: a kind of tumour, duration of the disease, prevalence of pain, manipulation and locomotive abilities, visibility of handicap; sociological factors including: age and sex of studied persons, the place of residence and education of parent's, living standard of the family, a degree of family participation in cultural life of the society, mother's attitude towards the insane child. These factors allow to formulate the following dependences: The more a level of the child's locomotive functions, following neoplastic disease approaches to the standard, the more favourable course takes the process of child's adaptation to the family and peers. If a neoplastic disease leaves permanent and always visible handicap then child's adaptation effect to the environment is not favourable. An active participation of the family in socially life is beneficial for regular adaptation of a child. Personality development as the result of participation in cultural life allows socially accepted defence mechanism to work in stress situations connected with the disease. Parent's rational attitude towards an insane child correlates with a beneficial child's adaptation to an environment. Other factors did not differentiate the two groups statistically. During clinicalontgenetic analysis concerning particular studied cases, 3 models of nonfunctional adaptation were distinguished: maladjustment of aggressive type prevailing among the children with permanent physical handicap coming of families characteristic for socially nonaccepted standard of behaviour; maladjustment of neurotic type prevailing among the children coming of compliant families whose adult members manifest neurotic vegetative reactions in difficult situations.(ABSTRACT TRUNCATED AT 400 WORDS)

Activities of Daily Living↗
PubMed2025

Constraints in temperature adaptation reinforce differences in thermal niche between mesophilic and psychrotolerant Bacillus cereus group species.

Experimental evolution has demonstrated that mesophilic microbes readily adapt to increases in temperature. However, many microbes are psychrotolerant and resistant to cold, which is associated with physiological specializations, suggesting constraints in thermal adaptation. We hypothesized that constraints would limit adaption differently in a mesophilic species (Bacillus thuringiensis) compared with its psychrotolerant relative B. mycoides-with adaptation at cooler temperatures and adaptation at higher temperatures being constrained in each species, respectively. To test this hypothesis, we imposed 140 generations of selection at temperatures at and below the optimum for productivity for both species. The fitness and thermal performance of evolved bacteria showed ancestral thermal niche plays a role in thermal adaptation over this time scale, in support of our hypothesis of adaptive constraints. Temperature-dependent trade-offs appeared common in B. mycoides, with fitness gains associated with decreases in operational niche width; fitness gains at one temperature caused a decrease in the range of temperatures that the bacterium showed appreciable growth. Genome resequencing showed that variation in mutation supply and selection strength could not explain temperature-dependent responses to selection. Importantly, metabolic theory only held true for mesophilic B. thuringiensis, showing abundant but less studied psychrotolerant species could follow different adaptive trajectories.

Bacillus thuringiensis↗
PubMed2025

Laboratory Evolution Reveals Transcriptional Mechanisms Underlying Thermal Adaptation of Escherichia coli.

Adaptive laboratory evolution is able to generate microbial strains, which exhibit extreme phenotypes, revealing fundamental biological adaptation mechanisms. Here, we use adaptive laboratory evolution to evolve Escherichia coli strains that grow at temperatures as high as 45.3 °C, a temperature lethal to wild-type cells. The strains adopted a hypermutator phenotype and employed multiple systems-level adaptations that made global analysis of the DNA mutations difficult. Given the challenge at the genomic level, we were motivated to uncover high-temperature tolerance adaptation mechanisms at the transcriptomic level. We employed independently modulated gene set (iModulon) analysis to reveal five transcriptional mechanisms underlying growth at high temperatures. These mechanisms were connected to acquired mutations, changes in transcriptome composition, sensory inputs, phenotypes, and protein structures. They are as follows: (i) downregulation of general stress responses while upregulating the specific heat stress responses, (ii) upregulation of flagellar basal bodies without upregulating motility and upregulation fimbriae, (iii) shift toward anaerobic metabolism, (iv) shift in regulation of iron uptake away from siderophore production, and (v) upregulation of yjfIJKL, a novel heat tolerance operon whose structures we predicted with AlphaFold. iModulons associated with these five mechanisms explain nearly half of all variance in the gene expression in the adapted strains. These thermotolerance strategies reveal that optimal coordination of known stress responses and metabolism can be achieved with a small number of regulatory mutations and may suggest a new role for large protein export systems. Adaptive laboratory evolution with transcriptomic characterization is a productive approach for elucidating and interpreting adaptation to otherwise lethal stresses.

Escherichia coli↗
PubMed2025

The Relationship Among Range Adaptation, Social Anhedonia, and Social Functioning: A Combined Magnetic Resonance Spectroscopy and Resting-State fMRI Study.

BACKGROUND AND HYPOTHESIS: Social anhedonia is a core feature of schizotypy and correlates significantly with social functioning and range adaptation. Range adaptation refers to representing a stimulus value based on its relative position in the range of pre-experienced values. This study aimed to examine the resting-state neural correlates of range adaptation and its associations with social anhedonia and social functioning. STUDY DESIGN: In study 1, 60 participants completed resting-state magnetic resonance spectroscopy and fMRI scans. Range adaptation was assessed by a valid effort-based decision-making paradigm. Self-reported questionnaires was used to measure social anhedonia and social functioning. Study 2 utilized 26 pairs of participants with high (HSoA) and low levels of social anhedonia (LSoA) to examine the group difference in range adaptation's neural correlates and its relationship with social anhedonia and social functioning. An independent sample of 40 pairs of HSoA and LSoA was used to verify the findings. STUDY RESULTS: Study 1 showed that range adaptation correlated with excitation-inhibition balance (EIB) and ventral prefrontal cortex (vPFC) functional connectivity, which in turn correlating positively with social functioning. Range adaptation was specifically determined by the EIB via mediation of ventral-medial prefrontal cortex functional connectivities. Study 2 found HSoA and LSoA participants exhibiting comparable EIB and vPFC connectivities. However, EIB and vPFC connectivities were negatively correlated with social anhedonia and social functioning in HSoA participants. CONCLUSIONS: EIB and vPFC functional connectivity is putative neural correlates for range adaptation. Such neural correlates are associated with social anhedonia and social functioning.

Humans↗
PubMed1979

Comparison and adaptation.

It has sometimes been suggested that the term adaptation should be reserved for differences with a known genetic basis. We argue that adaptation should be defined by its effects rather than by its causes as any difference between two phenotypic traits (or trait complexes) which increases the inclusive fitness of its carrier. This definition implies that some adaptations may arise by means other than natural selection. It is particularly important to bear this in mind when behavioural traits are considered. Critics of the 'adaptationist programme' have suggested that an important objection to many adaptive explanations is that they rely on ad-hoc arguments concerning the function of previously observed differences. We suggest that this is a less important problem (because evolutionary explanations generally claim some sort of generality and are therefore testable) than the difficulties arising from confounding variables. These are more widespread and more subtle than is generally appreciated. Not all differences between organisms are directly adapted to ecological variation. The form of particular traits usually constrains the form of value that other traits can take, presenting several obstacles to attempts to relate variation in morphological or behavioural characteristics directly to environmental differences. We describe some of the repercussions of differences in body size among vertebrates and ways in which these can be allowed for. In addition, a variety of evolutionary processes can produce non-adaptive differences between organisms. One way of distinguishing between these and adaptations is to investigate adaptive trends in phylogenetically different groups of species.

Adaptation, Biological↗
PubMed2026

Polygenic and monogenic adaptation drive evolutionary rescue at different magnitudes of environmental change.

Understanding the genetic basis of rapid adaptation is key to predicting species' evolutionary responses to environmental change. However, it is still debatable whether many small-effect mutations or a few large-effect mutations underlie rapid adaptation, and how this knowledge can predict population survival or extinction. To address this question, we performed a series of ecologically grounded forward-in-time genetic simulations to study rapid adaptation and extinction with increasing magnitudes of environmental change. These simulations were seeded with genomic variation of the plant Arabidopsis thaliana to have a realistic genomic structure, with one (monogenic) to 1,000 (polygenic) variants with varying heritabilities contributing to an environmental adaptive trait. Our results revealed two distinct scenarios of rapid adaptation and population rescue. Under small-to-moderate environmental shifts, high polygenic traits increased evolutionary rescue probability. Under extreme environmental shifts, high polygenic traits lead predictably to extinction, yet monogenic traits sometimes produce one-off winning adaptive genotypes. We interpret our rapid evolutionary rescue findings in terms of the fundamental theorem of natural selection, where trait polygenicity shapes the distribution of genetic variance in fitness across replicates and, in turn, the probability of population survival, with polygenic architectures producing more stable and predictable fitness variance and monogenic architectures generating highly skewed and variable outcomes. These results highlight the insights genomics gives us into the (un)predictability of species' evolutionary responses to global change, with management implications for assisted adaptation and conservation.

Arabidopsis↗
PubMed1977

Alterations of alkaline phosphatase activity during adaptation of Escherichia coli to phosphite and hypophosphite.

When Escherichia coli cells were grown in media containing either phosphite or hypophosphite as the sole source of phosphorus, the responded to this situation primarily in the same way as phosphate-limited cultures: The activity of alkaline phosphatase increased drastically, which under natural conditions would enable the cells to compensate for the shortage of phosphate. Subsequent transfers, however, resulted in a quite different response: While the phosphatase activity of phosphate-limited cells stays at a high derepressed level, its increase was followed by a gradual decline in organisms grown on phosphite of hypophosphite. After eight to ten transfers on these P-compounds, phosphatase activity was back to its initial, repressed, low level, indicating that the cells were fully adapted to these substrates. Adaptation to either PO3-3 or PO3-2 was completely abolished if the cells were again grown with PO3-3 as P-source, whereafter the entire process of adaptation had to be repeated. The observed adaptation pattern, reflected by the alterations of phosphatase activity, was qualitatively equal with PO3-3 and PO3-2, but quantitatively different, because the response to hypophosphite gave much higher values than the increase obtained with phosphite. Phosphite-adapted cells are not simultaneously adapted to hypophosphite, but their response to the latter was less intense than observed after direct transfers from PO3-4 to PO3-2. Adaptation to hypophosphite, however, led simultaneously to phosphite adaptation, so that these cells can utilize both P-compounds as a substitute for phosphate.

Adaptation, Physiological↗
PubMed2026

Genetically diverse populations hold the keys to climatic adaptation in the Western barn owl (Tyto alba).

Although local adaptation influences species distributions, its role in driving evolutionary resilience under climate change remains unclear. Current predictive models focus on genetic adaptation to present climates, providing limited insight into future adaptive capacity. We hypothesise that historical responses to climatic shifts can reveal candidate loci for local adaptation in the future. Combining ecological niche modelling and genomic analyses, we investigate spatiotemporal patterns and mechanisms of local adaptation of the Western Palearctic barn owl (Tyto alba). Ecological modelling reveals that barn owls now occupy a broader climatic niche than during the Last Glacial Maximum. Genomic analyses indicate ongoing adaptation, with regions under selection linked to environmental factors across all populations. We find that local adaptation drives evolutionary changes across populations, enabling colonisation of new habitats and shaping responses to climate change in resident populations. We show that standing genetic diversity plays a crucial role in adaptation to past, present, and future environmental shifts.

Animals↗
PubMed2026

Comparative analysis of olfactory receptor repertoires reveals evolutionary dynamics and high-altitude adaptation in Schizopygopsis younghusbandi based on the chromosome-level genomes.

The olfactory receptor (OR) gene represent a significant multigene family in vertebrates, forming the core molecular basis of olfactory perception and playing a crucial role in the environmental adaptation of species. High-altitude ecosystems represent extreme habitats characterized by specific abiotic stresses, including low oxygen levels, low temperatures, and intense ultraviolet radiation. These environments also exhibit low aquatic biodiversity and a limited variety of odor molecules, factors that have influenced the adaptive evolution of the sensory systems in endemic species. However, the genetic mechanisms underlying olfactory adaptation in high-altitude freshwater fish remained inadequately understood. In this study, we performed comparative genomics analyses to reveal the evolutionary processes underlying the adaptive and functional evolution of OR genes in S. younghusbandi, a cyprinid fish endemic to the Qinghai-Xizang Plateau. The results indicated that, compared to their low-altitude relatives, S. younghusbandi possessed a significantly smaller number of OR genes, with only 98 genes, which revealed the contraction of the gene family. Phylogenetic analysis revealed that the OR genes of cyprinid fish could be categorized into two major lineages: type I and type II. The η and δ families, which perceive water-soluble odors, in S. younghusbandi underwent significant and specific expansion, while the ε family was completely absent. This pattern reflected adaptive changes in olfactory recognition to accommodate the simplified odor spectrum of high-altitude water bodies. Chromosomal localization analysis demonstrated that OR genes were clustered, and collinearity analysis confirmed the presence of conserved genomic fragments among species. Selection pressure analysis revealed that the Ka/Ks values of all homologous gene pairs were less than 1, indicating that the OR genes of S. younghusbandi underwent strong purifying selection as a group to preserve core olfactory function. A few genes exhibited relaxed selection characteristics, which may have facilitated the fine-tuning of adaptability to high-altitude environments. In conclusion, this study elucidated the evolutionary dynamics and adaptive characteristics of the OR gene in S. younghusbandi, offering a new perspective on the molecular mechanisms underlying olfactory adaptation at high altitudes and enriching the research on sensory evolution in vertebrates.

Schizopygopsis younghusbandi↗
PubMed1978

Intracellular restriction of ecotropic murine leukemia virus in rat NRK cells and its abolishment by adaptation.

Ecotropic murine leukemia viruses, both N-tropic FN-2 (purified helper component of Friend leukemia virus) and B-tropic WNB-2 (purified WN1802B BALB/c-derived endogenous virus), were partially restricted in rat NRK cells. In NRK cells, they produced obscure small plaques at reduced efficiencies relative to their plaque-producing efficiencies in mouse SC-1 cells (10-fold for FN-2 and 100-fold for WNB-2). After three or four passages in NRK cells, the plaquing efficiencies of the viruses in NRK cells increased to levels close to their efficiencies in mouse cells, and the plaques in NRK cells became larger and clearer. The adaptation was more complete with FN-2 than with WNB-2. The adaptation was not due to simple selection of a virus in the FN-2 stock, but was host induced, as the viruses had been submitted to successive limiting dilutions in SC-1 cells before propagation in NRK cells. Possible commitment of xenotropic virus in the adaptation was excluded. The change was stable, even if the adapted viruses were propagated back into SC-1 cells. The NRK-adapted viruses were restricted in other rat cell lines of different origins, and the virus adapted in another rat cell line, RFL, was still restricted in NRK cells. The adaptation was mainly brought about by increased viral growth within the rat cells and not by an increased efficiency of viral penetration into the rat cells. This inversely suggests that the restriction of the ecotropic murine leukemia viruses in NRK cells was a mainly intracellular event. The mobilities of gp69/71 and p30 in sodium dodecyl sulfatepolyacrylamide gel electrophoresis remained unchanged after adaptation of FN-2 in NRK cells.

Adaptation, Biological↗
PubMed1979

Effects of noradrenaline and nicotinic acid on plasma free fatty acids and oxygen consumption in cold-adapted rats.

A 3-h noradrenaline (NA) infusion (1.5 microgram kg-1 min-1) produced a sustained enhanced oxygen consumption (O2 cons.) in cold-adapted rats. Plasma free fatty acid (FFA) levels were elevated by NA in control and in cold-adapted rats, but to lesser extent in cold-adapted rats; the increase was maintained at a plateau in both groups during the entire period of NA infusion. A 1-h nicotinic acid (Nic A) infusion (1.5 mg kg-1 min-1) added to the NA infusion inhibited the calorigenic response to NA in cold-adapted rats and reduced the elevated plasma FFA concentration in control and in cold-adapted rats to values below basal levels. However, when the Nic A infusion was stopped, the O2 cons. was increased again in cold-adapted rats by the uninterrupted NA infusion, without the simultaneous increase of the plasma FFA concentration; the plasma FFA concentration was maintained in cold-adapted rats below basal values and merely brought back to basal levels in control rats. From these results, it is suggested that plasma FFA are not an essential substrate to the calorigenic response to NA observed in cold-adapted rats, as 85% of the response can occur when the plasma FFA concentration is very low.

Adaptation, Physiological↗
PubMed2025

Pan-Genome Analysis Reveals Local Adaptation to Climate Driven by Introgression in Oak Species.

The genetic base of local adaptation has been extensively studied in natural populations. However, a comprehensive genome-wide perspective on the contribution of structural variants (SVs) and adaptive introgression to local adaptation remains limited. In this study, we performed de novo assembly and annotation of 22 representative accessions of Quercus variabilis, identifying a total of 543,372 SVs. These SVs play crucial roles in shaping genomic structure and influencing gene expression. By analyzing range-wide genomic data, we identified both SNPs and SVs associated with local adaptation in Q. variabilis and Quercus acutissima. Notably, SV-outliers exhibit selection signals that did not overlap with SNP-outliers, indicating that SNP-based analyses may not detect the same candidate genes associated with SV-outliers. Remarkably, 29%-37% of candidate SNPs were located in a 250 kb region on chromosome 9, referred to as Chr9-ERF. This region contains 8 duplicated ethylene-responsive factor (ERF) genes, which may have contributed to local adaptation of Q. variabilis and Q. acutissima. We also found that a considerable number of candidate SNPs were shared between Q. variabilis and Q. acutissima in the Chr9-ERF region, suggesting a pattern of repeated selection. We further demonstrated that advantageous variants in this region were introgressed from western populations of Q. acutissima into Q. variabilis, providing compelling evidence that introgression facilitates local adaptation. This study offers a valuable genomic resource for future studies on oak species and highlights the importance of pan-genome analysis in understating mechanism driving adaptation and evolution.

Quercus↗
PubMed2025

Resource presentation dictates genetic and phenotypic adaptation in yeast.

BACKGROUND: Environments shape adaptive trajectories of populations, often leading to adaptive parallelism in identical, and divergence in different environments. However, how does the likelihood of these possibilities change with minute changes in the environment remain unclear. RESULTS: In this study, we evolved Saccharomyces cerevisiae in environments which differed only in the manner in which the sugar source is presented to the population. In one set of populations, carbon was presented as a mixture of glucose-galactose, and in the other, as melibiose, a glucose-galactose disaccharide. Since the two environments differed in how the two monosaccharides are packaged, we call these environments 'synonymous'. Our results show that even subtle environmental differences can lead to differing phenotypic responses between the two sets of evolved populations. However, despite different adaptive responses, pleiotropic effects of adaptation are largely predictable. We also show that distinct genomic targets of adaptation between the two sets of evolved populations are functionally convergent. CONCLUSION: This study highlights how subtle environmental differences dictate phenotypic and genetic adaptation of populations. Additionally, these results also suggest the predictive potential of ancestor's fitness in understanding pleiotropic responses. Our work underscores the importance of studying more such environments to understand the generality of adaptive responses in populations.

Saccharomyces cerevisiae↗
PubMed1979

Relationship between adaptation and the percept and transformations of stop consonant voicing: effects of the number of repetitions and intensity of adaptors.

Important issues in selective adaptation research concern the relative contribution of response related (perceptual) and stimulus related (acoustic) effects of the adaptor in the adaptive process. Two response related issues pertain to the effects of the adaptor percept and verbal transformations on adaptation. This investigation systematically examined perceptual and acoustic contributions of the adaptor on the adaptation of the voicing feature. Subjects rated the degree of voicing/voicelessness of end-point VOT adaptors, i.e., 5- and 55-ms VOT, and an acoustically neutral adaptor, i.e., 25-ms VOT, during periods of repetitions. The number of adaptor repetitions during each of ten trials was either 5, 32, or 95, and the intensity of the adapting stimulus was either 50, 70, or 90 dB SPL. The major findings were as follows: (1) No significant correlations were found between ratings of voicing percept of the adaptor and magnitude of boundary shift; (2) Increases in repetitions and relative intensity level of end-point adaptors produced significantly greater phonetic boundary shifts and generally greater affects on ratings of test stimuli; and (3) The end-point adaptors produced significant shifts in rating of boundary and nonboundary stimuli. The findings indicate that neigher the adaptor percept or verbal transformations affected the magnitude of adaptation. These results and those for acoustic parameters strongly suggest an acoustic as opposed to a phonetic basis of adaptation of the voicing feature. Furthermore, the effects of end-point adaptors on boundary and nonboundary stimuli support the generalized change in feature sensitivity assumed by a fatigue model of adaptation.

Acoustic Stimulation↗
PubMed1979

Functional profile of the isolated uremic nephron: potassium adaptation in the rabbit cortical collecting tubule.

As a renal function declines in patients and experimental animals with chronic renal disease, potassium homeostasis is maintained by a progressive increase in potassium secretion by the surviving nephrons, a phenomenon known as potassium adaptation. To determine the nephron site and the underlying mechanisms responsible for this phenomenon, studies were performed on normal and 75% nephrectomized rabbits maintained on normal or high-potassium diets. Cortical collecting tubules (CCT) were dissected from the normal and remnant kidneys and perfused in vitro in an artificial solution. In normal CCT mean (+/- SE) net K secretion, JK, (peq/cm per s) was 1.26 +/- 0.43 (normal diet) and 3.27 +/- 0.66 (high-K diet). In uremic CCT, JK was 3.55 +/- 0.60 (normal diet) and 6.83 +/- 0.58 (high-K diet). By reducing the dietary intake of potassium in proportion to the reduction of renal mass in these uremic animals, the adaptation in K secretion was prevented (JK: 1.22 +/- 0.40). Transepithelial potential difference was similar in CCT from normal and uremic animals on a normal diet despite the fact that JK was significantly greater in the latter group. However, in both normal and uremic CCT, the increase in JK caused by potassium loading was associated with an increase in luminal negativity. Uremic CCT underwent significant compensatory hypertrophy regardless of the dietary intake or potassium secretory rates. Plasma aldosterone levels were elevated only in the uremic-high potassium rabbits suggesting that a mineralocorticoid effect on the CCT may be exaggerated when potassium loading is superimposed upon decreased excretory capacity. The activity of Na-K ATPase was comparable in normal and uremic CCT from rabbits on either normal or high-K diets indicating that potassium adaptation may occur independently of changes in the activity of this enzyme. Intracellular potassium content measured chemically and by 42K exchange, was not significantly altered in either normal or uremic CCT when dietary potassium intake was increased, despite the fact the JK was increased under these circumstances. These data indicate that the CCT is an important site of potassium adaptation in the surviving nephrons of animals with reduced renal mass. This adaptation is an intrinsic property of the CCT and is expressed in the absence of a uremic milieu. Potassium adaptation by the uremic CCT is not fixed according to the degree of compensatory hypertrophy but varies according to the excretory requirements of the animal. Transepithelial potential difference and circulating aldosterone levels contribute to the adaptation but neither factor can entirely account for the phenomenon. Potassium adaptation by the CCT occurs in the absence of changes in Na-K ATPase activity and intracellular potassium content.

Animals↗
PubMed1978

Ear dominance effects in loudness following auditory adaptation.

In recent years there has been much attention to the study of ear differences in the response to auditory stimuli. However, the possibly of ear differences in auditory adaptation effects has apparently not been investigated. The present authors used a monaural heterophonic balance to investigate the adaptation of a 500 Hz adapting tone. Ten subjects were tested in the left ear, ten in the right. Left ear adaptation was 4.20 dB, while right ear adaptation was 12.88 dB (p is less than or equal to .001). Previous differences in binaural adaptation studies could conceivably have been partially influenced by the ear adapted. It is suggested that the possibility of ear differences in loudness adaptation be taken into account in future studies.

Adolescent↗
PubMed1978

[Influence of adaption level upon oscillatory potential in the electroretinogram (author's transl)].

Oscillatory potentials (OP's) were recorded using constant energy stimulating from 2.5 J at different levels of adaptation from 400 to 30 fl, as well as pre-dark adaptation. O1, O2, and O3 regularly appear in the ascending branch of the b-wave complex, and after pre-dark adaptation the less differentiated O4 and O5 appear as well, exhibiting variable potental heights and durations as the dark time progresses. With intensive pre-light adaptation there is a relative reduction of potential, as is also true following weak prelight adaptation or dark adaptation; the culmination time in the former case being more rapid, and in the latter case slower. Good discrimination of the OP with a concurrent diminution in the amplitudes was only observed after a pre-dark adaptation.

Adaptation, Physiological↗