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PubMed1996

Pemenone and androstenone do not cross-adapt reciprocally.

Explorations of the qualitative and quantitative differences between the odors of pemenone (PEM), androstenone (AND) and isovaleric acid (IVA) show that they share a number of common perceptual characteristics. Among these are similarities in their odor quality and relative intensity ratings. PEM is also an efficient cross-adaptor and modulator of a subject's AND sensitivity. Here we evaluate the reciprocal efficacy of AND adaptation to alter the perceived intensity and quality of PEM, IVA and AND. Twenty-three people, including both those osmic and allosmic (n = 11) for the putrid odor quality of PEM, were tested. Following training in odor quality and intensity rating techniques, subjects sampled a selected substance for 2 min to obtain adaptation and then reported quality and intensity ratings for the three test stimuli. There was significant self-adaptation by PEM and IVA in all subjects, but self-adaptation by AND was only observed in the PEM-osmic subjects. AND did not cross-adapt PEM or IVA to any significant extent. Collectively, these results contrast with our earlier study in which PEM was an efficient cross-adaptor of AND. Here, AND was no more efficient than the control as an adapting substance for PEM, despite significant self-adaptation of PEM by itself. This lack of reciprocity in the effectiveness of PEM and AND as cross-adapters is not related to differences in odor intensity, as the PEM and AND concentrations were adjusted for each subject to elicit comparable intensity reports. These results support the notion that PEM, AND and IVA share certain perceptual characteristics, but interact differentially with three or more sets of perceptual channels that are now thought to result in a putrid odor quality.

Adaptation, Physiological↗
PubMed1999

Mutational adaptation of Escherichia coli to glucose limitation involves distinct evolutionary pathways in aerobic and oxygen-limited environments.

Mutational adaptations leading to improved glucose transport were followed with Escherichia coli K-12 growing in glucose-limited continuous cultures. When populations were oxygen limited as well as glucose limited, all bacteria within 280 generations contained mutations in a single codon of the ptsG gene. V12F and V12G replacements in the enzyme IIBC(Glc) component of the glucose phosphotransferase system were responsible for improved transport. In stark contrast, ptsG mutations were uncommon in fully aerobic glucose-limited cultures, in which polygenic mutations in mgl, mlc, and malT (regulating an alternate high-affinity Mgl/LamB uptake pathway) spread through the adapted population. Hence the same organism adapted to the same selection (glucose limitation) by different evolutionary pathways depending on a secondary environmental factor. The clonal diversity in the adapted populations was also significantly different. The PtsG V12F substitution under O(2) limitation contributed to a universal "winner clone" whereas polygenic, multiallelic changes led to considerable polymorphism in aerobic cultures. Why the difference in adaptive outcomes? E. coli physiology prevented scavenging by the LamB/Mgl system under O(2) limitation; hence, ptsG mutations provided the only adaptive pathway. But ptsG mutations in aerobic cultures are overtaken by mgl, mlc, and malT adaptations with better glucose-scavenging ability. Indeed, when an mglA::Tn10 mutant with an inactivated Mgl/LamB pathway was introduced into two independent aerobic chemostats, adaptation of the Mgl(-) strain involved the identical ptsG mutation found under O(2)-limited conditions with wild-type or Mgl(-) bacteria.

Adaptation, Physiological↗
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↗
PubMedDate not supplied

Factors that influence adolescent adaptation to sickle cell disease.

OBJECTIVE: To examine whether psychosocial factors play a more important role than biomedical risk factors in predicting adolescent adaptation to sickle cell disease (SCD); to determine whether psychosocial factors moderate the relationship between biomedical risk factors and adaptation. METHODS: Ninety African American adolescents from the multisite Cooperative Study of Sickle Cell Disease were recruited to complete a battery that included measures of psychosocial status and psychological adaptation. Data regarding their health status were collected from medical records. RESULTS: The findings revealed that intrapersonal (self-esteem, social assertiveness), stress-processing (use of social support), and social ecological factors (family relations) were significant predictors of adaptation; however, biomedical factors did not predict adaptation. There was no evidence that psychosocial factors moderated the relationship between biomedical risk factors and adaptation. CONCLUSIONS: Psychosocial factors proved to be better predictors of adaptation than biomedical risk factors. Additional research is needed to better understand the nature of the interrelationships among biomedical risk factors, psychosocial factors, and adaptation.

Adaptation, Psychological↗
PubMed2001

Only UCP1 can mediate adaptive nonshivering thermogenesis in the cold.

Adaptive nonshivering thermogenesis may have profound effects on energy balance and is therefore therefore is a potential mechanism for counteracting the development of obesity. The molecular basis for adaptive nonshivering thermogenesis has remained a challenge that sparked acute interest with the identification of proteins (UCP2, UCP3, etc.) with high-sequence similarity to the original uncoupling protein-1 (UCP1), which is localized only in brown adipose tissue. Using UCP1-ablated mice, we examined whether any adaptive nonshivering thermogenesis could be recruited by acclimation to cold. Remarkably, by successive acclimation, the UCP1-ablated mice could be made to subsist for several weeks at 4C during which they had to constantly produce heat at four times their resting levels. Despite these extreme requirements for adaptive nonshivering thermogenesis, however, no substitution of shivering by any adaptive nonshivering thermogenic process occurred. Thus, although the existence of, for example, muscular mechanisms for adaptive nonshivering thermogenesis has recurrently been implied, we did not find any indication of such thermogenesis. Not even during prolonged and enhanced demand for extra heat production was any endogenous hormone or neurotransmitter able to recruit any UCP1-independent adaptive nonshivering thermogenic process in muscle or in any other organ, and no proteins other than UCP1-not even UCP2 or UCP3-therefore have the ability to mediate adaptive nonshivering thermogenesis in the cold.

Adaptation, Physiological↗
PubMed2006

Long-term outcomes of adaptive functions for children with mucopolysaccharidosis I (Hurler syndrome) treated with hematopoietic stem cell transplantation.

Advances in medical treatment have prolonged the lives of children with Hurler syndrome or mucopolysaccharidosis I requiring increased attention to the assessment of their long-term outcomes and functional abilities. Adaptive functions are critical for understanding functional outcomes after treatment and developing focused interventions. We investigated the development of various adaptive functions in children who have had hematopoietic stem cell transplant (HSCT) for Hurler syndrome and risk factors that are associated with the development of these functions. We examined the development of 41 children who had 3 or more Vineland Adaptive Behavior Scales records assessed before and after transplant. Communication, daily living skills, socialization, and motor functions were measured. While standard scores decline over time, development of skills continue with a slower than average rate compared with peers. A cross-sectional nontransplanted comparison group showed more deficits after age 2 years than the transplanted group. In contrast to cognitive ability, age at transplant was not significantly associated with ultimate adaptive level. Baseline cognitive level before HSCT and growth of cognition after HSCT were associated with adaptive functions especially for communication and daily living skills. Socialization was predicted by cumulative medical risk factors, likely due to restricted social exposure in children with complicated transplant courses. Overall, measurement of adaptive behaviors demonstrated that HSCT allows long-term slow improvement of functional outcomes for children with Hurler syndrome. Children with Hurler syndrome with good cognitive levels before HSCT and continued growth of cognition after HSCT show good adaptive functions. Although cognitive and orthopedic problems as well as medical complications limit adaptive ability, identifying these problems early allow beneficial targeted interventions.

Activities of Daily Living↗
PubMed1999

Dietary lipids influence intestinal adaptation after massive bowel resection.

BACKGROUND: Certain lipids, primarily long chain fatty acids and especially long chain polyunsaturated fatty acids (LCPUFAs) from marine oils, stimulate gut adaptation after resection. The goal of this study was to define the degree of resection that provides an optimal model for adaptation and to determine if dietary LCPUFAs improve intestinal adaptation after resection. METHODS: One hundred and fifty-g male Sprague-Dawley rats were divided into groups receiving 60%, 70%, and 80% bowel resection. After resection, each group was subdivided into two dietary groups and pair fed diets containing either safflower oil or docosahexaenoic acid (DHA) and arachidonic (AA). RESULTS: After 2 weeks, mucosal mass, protein, DNA, and disaccharidase activity were measured in the remaining intestine. Rats receiving 80% resection responded with the highest level of intestinal adaptation. Within the 80% resection group, diet containing DHA and AA stimulated adaptation significantly more than safflower diet. A second study further evaluated the effect on LCPUFAs on intestinal adaptation. Diets included a control group 10% soy oil, and three diets differing in their AA-DHA fat blend ratio at 5% AA and 3.3% DHA, 15% AA and 10% DHA, and 45% AA and 30% DHA. The addition of LCPUFAs to diets enhanced intestinal adaptation in a linear, dose-dependent manner after an 80% small bowel resection. Rats fed a diet containing 30% DHA-45% AA had significantly enhanced mucosal mass compared to rats fed a diet containing 10% soy oil, and considerably higher compared to rats fed 3.3% DHA-5% AA. CONCLUSIONS: These studies suggest that modification of dietary LCPUFAs may enhance intestinal adaptation in short bowel syndrome.

Adaptation, Physiological↗
PubMed1988

Imbalanced adaptation of accommodation and vergence produces opposite extremes of the AC/A and CA/C ratios.

It is customary to describe abnormal interactions between accommodation and convergence according to the Duane-White classification of convergence excess and insufficiency or divergence excess and insufficiency. However, recent studies indicate that these extremely high and low categories of accommodative vergence may result from adaptive disorders of accommodation and convergence. The AC/A ratio is shown in this paper to vary inversely with adaptability of accommodation and to vary directly with adaptability of vergence. Extremely high AC/A ratios can result from an imbalance in which vergence adapts readily to prism, whereas accommodation does not adapt to minus lenses. Similarly, extremely high values for convergence accommodation (the CA/C ratio) are observed when there is robust adaptation of accommodation to lenses and little adaptation of vergence to prism. Furthermore, in these extreme cases the AC/A and CA/C ratios tend to be inversely related. For example, abnormally high AC/A ratios are often accompanied by extremely low CA/C ratios and vice versa. These observations suggest that equalizing the adaptability of accommodation and vergence with orthoptics may prove to be an effective means of restoring the AC/A and CA/C ratios to normal values.

Accommodation, Ocular↗
PubMed1994

Effect of vitamin A treatment on the prolongation of dark adaptation in Stargardt's dystrophy.

BACKGROUND: Prolongation in recovery of rod thresholds has been demonstrated in Stargardt's dystrophy. One possible explanation for this finding includes an impairment of vitamin A transport by the retinal pigment epithelium (RPE). By delivering an increased amount of vitamin A to the RPE, it might be possible to overcome a relative deficiency of vitamin A utilization or transport, and thus improve rod dark adaptation. METHODS: Baseline dark-adapted rod final thresholds were measured for five patients with Stargardt's dystrophy after 60 minutes of dark adaptation. A full dark-adaptation curve was then measured after exposure to a bleaching light for 5 minutes. Time of recovery to within 0.2 log units of the prebleach dark-adapted rod threshold was determined. Each subject then took a 14- to 18-day course of oral vitamin A, 50,000 IU daily. Dark adaptation was then reassessed using the same pretreatment protocol. RESULTS: Before treatment, all five patients had a prolongation of their rod recovery curve. There was no statistically significant difference between subjects in mean time taken to reach prebleach rod baseline thresholds before and after vitamin A treatment. CONCLUSIONS: These findings do not rule out the possibility that a delay in rod dark adaptation in Stargardt's dystrophy results from an inability to transport vitamin A from the RPE to photoreceptor cells. Nevertheless, a high dose of oral vitamin A taken for at least 14 days did not provide any objective improvement in dark-adaptation function in five such patients.

Administration, Oral↗
PubMed2005

Dynamics of saccadic adaptation: differences between athletes and nonathletes.

PURPOSE: The aim of the study was to delineate differences in saccadic adaptation characteristics between a population of racquet sports athletes and nonathletes. METHODS: Eye movements were recorded at 120 Hz using a video-based eye tracker (ELMAR 2020) in a sample of 27 athletes (varsity badminton and squash players) and 14 nonathletes (<3 hours/week participation in recreational sports). Responses to negative positional error and positive positional error were studied in two sessions on separate days. Negative positional errors were induced by displacing the stimuli backwards by 3 degrees from the initial target step (12 degrees). Likewise, positive positional errors were induced by displacing the stimuli forward by 3 degrees . Amplitude gains were calculated for trials before, during, and after the adaptation phase. The magnitude and the rate of change of saccadic adaptation were determined from the amplitude gains. Differences between the groups were compared using regression analysis. RESULTS: No significant differences were found between the two groups in the magnitude of saccadic adaptation, both for negative (athletes -60%, nonathletes -57%) and positive (athletes +26%, and nonathletes +27%) positional error. Racquet sports athletes showed a significantly faster rate of adaptation for the positive positional error. A significant difference was not observed in the rate of adaptation for the negative positional error. CONCLUSIONS: Racquet sports athletes and nonathletes adapt to positional error signals by similar amounts. However, racquet sports athletes respond to positive positional errors at a faster rate, suggesting that a strategic component or environmental influences (such as practice) may play a role in saccadic adaptation.

Adaptation, Ocular↗
PubMed1995

Studies on adaptation to complete dentures. Part II: Oral stereognosis and tactile sensibility.

High oral perception is thought to contribute to poor adaptation to new dentures. The aim of this study was to evaluate the oral stereognosis and tactile sensibility in edentate subjects and relate these to patient age and capability of adaptation to new prostheses. A total of 67 patients were provided with new complete dentures 2-3 weeks before the experiment. In 54 subjects, the oral stereognosis was evaluated by 12 different test-pieces, which were placed unseen on the tongue and had to be recognized. In 38 patients, the oral tactile sensibility was determined in the premolar area using copper foils. The capability of adaptation was evaluated by a questionnaire. Denture retention was assessed by clinical examination. The number of correctly identified test-pieces and the average identification time were related to the age, but no relation was found to patients' capability of adaptation. The tactile sensibility was found to be impaired with age and diminished capability of adaptation. Both adaptation and oral tactile sensibility were significantly lower in subjects with poor lower-denture retention. In conclusion, the results cannot support a relationship between high oral stereognosis and adaptation problems. However, good denture retention facilitates the adaptation process.

Adaptation, Psychological↗
PubMed1986

Effects of prolonged forced vergence upon the adaptation system.

In previous studies the ability of the oculomotor system to adapt to prism-induced heterophoria has been shown. The 'phoria that occurs immediately after a prism has been placed before one eye gradually reduces and returns to its original baseline value as the subject is allowed binocular experience while wearing the prism. Little work has been carried out to determine when the adaptation is complete. In this study we report on the results of two experiments designed to determine when adaptation is complete. In the first, the rate of decay of adaptation, i.e. loss of slow fusional vergence, is measured after varying periods of forced vergence. In the second experiment the rate of adaptation to an additional disparity is measured; this should be the same as that before the induced effect if adaptation is complete. The results of this study indicate that although adaptation may appear complete by the criterion that the 'phoria has returned to its baseline value, the adaptation is unlikely to be truly complete for a much longer period of time has passed.

Adaptation, Ocular↗
PubMed1989

Adaptive disorders of accommodation and vergence in binocular dysfunction.

Disturbances of binocular vision are described clinically by the Duane-White classification in terms of the magnitude of the accommodative-convergence ratio (AC/A). Convergence excess and convergence insufficiency are assumed to result from high and low AC/A ratios respectively. It is assumed that the abnormal AC/A ratio is an independent variable that underlies abnormal phorias. However, recent studies have demonstrated that the AC/A ratio is inversely related to the adaptability of tonic accommodation (lens adaptation) and directly related to adaptability of tonic vergence (prism adaptation). We have tested whether clinical categories of convergence excess and convergence insufficiency are associated with insufficient and excessive adaptation of tonic accommodation and tonic vergence. Results demonstrate greater amplitude and duration of accommodative after-effects (lens adaptation) in the convergence insufficiency than the convergence excess group. Vergence after-effects (prism adaptation) had the reverse trend for the two groups. These results indicate that adaptive disorders of accommodation and vergence may underlie binocular disorders in symptomatic patients categorized as convergence excess and convergence insufficiency.

Accommodation, Ocular↗
PubMed1993

Accommodative adaptation and age of onset of myopia.

Tonic accommodation in an empty field and accommodative adaptation, defined as accommodation shift after 2 min viewing of a 4 D near task, were measured using an infrared optometer. Subjects were classified into three types: emmetropes (n = 18), early onset myopes (n = 18) and late onset myopes (n = 15). The relationship between accommodative adaptation and the onset age of myopia were compared. There was no statistical difference in the pre-task tonic accommodation among the three subject groups. However, the accommodative adaptation differed in the three groups during the 5 min post-task period. The average accommodative adaptation of emmetropia, early onset myopia and late onset myopia were 0.66, 0.27 and 1.19 D, respectively. Accommodative adaptation in the late onset myopia group was significantly higher than in the emmetropia group. Furthermore, the accommodative adaptation in the early onset myopia group was significantly lower than in the emmetropia group. Two possible aetiologies of myopia are discussed: one for the group which shows low accommodative adaptation that has no relationship with the age of onset and another for the group which shows high accommodative adaptation that has a relationship to an onset age of 15 years or later. The aetiology is also considered with regard to a potentiating chemical effect on the synapses of the ciliary muscle.

Accommodation, Ocular↗
PubMed2005

Adaptation of muscle size and myofascial force transmission: a review and some new experimental results.

This paper considers the literature and some new experimental results important for adaptation of muscle fiber cross-sectional area and serial sarcomere number. Two major points emerge: (1) general rules for the regulation of adaptation (for in vivo immobilization, low gravity conditions, synergist ablation, tenotomy and retinaculum trans-section experiments) cannot be derived. As a consequence, paradoxes are reported in the literature. Some paradoxes are resolved by considering the interaction between different levels of organization (e.g. muscle geometrical effects), but others cannot. (2) An inventory of signal transduction pathways affecting rates of muscle protein synthesis and/or degradation reveals controversy concerning the pathways and their relative contributions. A major explanation for the above is not only the inherently limited control of the experimental conditions in vivo, but also of in situ experiments. Culturing of mature single Xenopus muscle fibers at high and low lengths (allowing longitudinal study of adaptation for periods up to 3 months) did not yield major changes in the fiber cross-sectional area or the serial sarcomere number. This is very different from substantial effects (within days) of immobilization in vivo. It is concluded that overall strain does not uniquely regulate muscle fiber size. Force transmission, via pathways other than the myotendinous junctions, may contribute to the discrepancies reported: because of substantial serial heterogeneity of sarcomere lengths within muscle fibers creating local variations in the mechanical stimuli for adaptation. For the single muscle fiber, mechanical signalling is quite different from the in vivo or in vitro condition. Removal of tensile and shear effects of neighboring tissues (even of antagonistic muscle) modifies or removes mechanical stimuli for adaptation. It is concluded that the study of adaptation of muscle size requires an integrative approach taking into account fundamental mechanisms of adaptation, as well as effects of higher levels of organization. More attention should be paid to adaptation of connective tissues within and surrounding the muscle and their effects on muscular properties.

Adaptation, Physiological↗
PubMed2005

Crystal structure of a subtilisin-like serine proteinase from a psychrotrophic Vibrio species reveals structural aspects of cold adaptation.

The crystal structure of a subtilisin-like serine proteinase from the psychrotrophic marine bacterium, Vibrio sp. PA-44, was solved by means of molecular replacement and refined at 1.84 A. This is the first structure of a cold-adapted subtilase to be determined and its elucidation facilitates examination of the molecular principles underlying temperature adaptation in enzymes. The cold-adapted Vibrio proteinase was compared with known three-dimensional structures of homologous enzymes of meso- and thermophilic origin, proteinase K and thermitase, to which it has high structural resemblance. The main structural features emerging as plausible determinants of temperature adaptation in the enzymes compared involve the character of their exposed and buried surfaces, which may be related to temperature-dependent variation in the physical properties of water. Thus, the hydrophobic effect is found to play a significant role in the structural stability of the meso- and thermophile enzymes, whereas the cold-adapted enzyme has more of its apolar surface exposed. In addition, the cold-adapted Vibrio proteinase is distinguished from the more stable enzymes by its strong anionic character arising from the high occurrence of uncompensated negatively charged residues at its surface. Interestingly, both the cold-adapted and thermophile proteinases differ from the mesophile enzyme in having more extensive hydrogen- and ion pair interactions in their structures; this supports suggestions of a dual role of electrostatic interactions in the adaptation of enzymes to both high and low temperatures. The Vibrio proteinase has three calcium ions associated with its structure, one of which is in a calcium-binding site not described in other subtilases.

Adaptation, Physiological↗
PubMed1991

Potential-dependent potassium currents in the rapidly adapting stretch receptor neuron of the crayfish.

The outward current was analysed in the rapidly adapting stretch receptor neuron of the crayfish Pacifastacus leniusculus with a two-micropipette potential clamp technique and K(+)-selective microelectrodes in an attempt to establish if the properties of this current could explain the difference in adaptive behaviour compared to the slowly adapting receptor. A fast activating outward current carried by K+ was revealed. The time constant of activation(tau n) was dependent on potential and had a mean value of 0.5 ms at potential steps to 0 mV. Activation followed a second-order process according to the Hodgkin-Huxley model. The potential dependence of activation (n infinity) followed by a sigmoid curve n infinity = 1/(1 + exp/[(E - En)/a]) with a half maximal activation potential En = -44 mV and a = -13 mV. When long pulses were applied the outward potassium current decreased with two time constants, one that was potential independent (0.2 s) and one that was potential dependent (2-8 s). The latter could be explained by accumulation of K+ in the extracellular space of the neuron. The potential dependence of inactivation followed a sigmoid function infinity = 1/(1 + exp[(E - Ek)/+a]) with Ek = -36 mV and a = 13 mV. The inactivation properties are different from those of the classical fast transient (IA) current. The transport system for the outward potassium current during depolarizing potential steps in the rapidly adapting stretch receptor is similar to the current found in the slowly adapting receptor neuron. However, the activation is faster and seems to occur at potentials more negative than in the slowly adapting receptor. These differences can contribute to but not entirely explain the difference in adaptive behaviour between the slowly and rapidly adapting receptor.

Action Potentials↗
PubMed1968

Adaptation in the goldfish retina.

1. Isolated photopic goldfish retinas were stimulated and adapted by red light, and the spike activity of single ganglion cells was monitored by micro-electrodes.2. A unit's threshold to illumination of one part of its receptive field was often raised by adapting spots which fell elsewhere. An adapting spot of fixed area and intensity always desensitized the unit most when focused at the test position.3. When adapting and testing spots were given concentrically, the large adapting spots raised the test threshold more than the smaller adapting spots, even though all completely covered the test spot. Quantitative considerations rule out scattered light as an explanation; there must be a neural mechanism, an adaptation pool, which sets the sensitivity on the basis of quanta received over a field hundreds of microns in diameter.4. The desensitization is a non-linear function of area and intensity.5. The adaptation pool's field is not coincident with the ganglion cell's receptive field.

Action Potentials↗