In this series of articles we have illustrated how physiological processes enable adaptation to changing situations such as those associated with surgery. Homeostasis has formed the central theme for relating physiology to well being, and the articles have largely been concerned with the homeostatic regulation of specific systems or processes ...

Oscillations in many regions of the cortex have common temporal characteristics with dominant frequencies centered around the 40 Hz (gamma) frequency range and the 5-10 Hz (theta) frequency range. Experimental results also reveal spatially synchronous oscillations, which are stimulus dependent (Gray & Singer, 1987; Gray, Konig, Engel, & Singer, 1989; ...

The ability of a species to adapt to stress factors such as exposure to toxicants depends to a large extent on the presence of individuals that are able to respond to the exposure in a successful way. Several strategies can be employed to cope with different stress factors. Investments on ...

Extracellular recordings of action potentials were made from directional neurons in the nucleus of the optic tract (NOT) of the wallaby, Macropus eugenii, while stimulating with moving sine-wave gratings. When a grating was moved at a constant velocity in the preferred direction through a neuron's receptive field, the firing rate ...

Probe-flash threshold curves were used to show that adaptation to textured fields consists not only of adaptation to the steady local constituents but also of a process that is similar to habituation to prolonged temporal modulation, which in this case could be caused by miniature eye movements across element boundaries. ...

Two functionally and anatomically distinct types of lateral inhibition contribute to the receptive field organization of ganglion cells in the vertebrate retina: sustained lateral inhibition (SLI), which is present during steady illumination and transient lateral inhibition (TLI), evoked by changes in illumination. We studied adaptive changes in these two lateral ...

The concepts of stress and distress are integral parts of consideration of animal well-being. Generally, stress refers to a state of threatened homeostasis, but precise clinical definitions, causes, and biological measurements have been controversial and confusing. Numerous factors associated with needs, life in captivity, threatening events, or aversive stimuli may ...

Studies of mechanisms of adaptive behavior generally focus on neurons and circuits. But adaptive behavior also depends on interactions among the nervous system, body and environment: sensory preprocessing and motor post-processing filter inputs to and outputs from the nervous system; co-evolution and co-development of nervous system and periphery create matching ...

We investigated the constraints for visuo-motor adaptation in human pointing movements. Subjects pointed at sequentially presented visual targets while visual feedback about their finger position was either absent (pre- and post-period), or was manipulated such as to require a gradual reduction of response amplitude (per-period). We found that response amplitudes ...

Hair cells of inner ear organs sensitive to frequencies above 10 Hz adapt to maintained hair bundle deflections at rates that reduce their responses to lower frequencies. Mammalian vestibular organs detect head movements at frequencies well below 10 Hz. We asked whether hair cells of the mouse utricle adapt, and ...

The characteristics of biological systems of adaptation are developed from the principle that the manifestations of life are modified by and must conform with their environment in order to enable organismic persistence. The two roles of the environment, termed "modifying" and "adaptive", give rise to the distinction of three elementary ...

OBJECTIVE: To study whether an electrosurgery device interferes with the operation of a low-power spread-spectrum wireless network adapter. METHODS: Nonrandomized, unblinded trials with controls, conducted in the corridor of our institution's operating suite using two portable computers equipped with RoamAbout omnidirectional 250 mW spread-spectrum 928 MHz wireless network adapters. To ...

An investigation of adaptation to palatal modification in [s] production was conducted using acoustic and perceptual analyses. The experiment assessed whether adaptation would occur subsequent to a brief period of intensive, target-specific practice. Productions of [sa] were elicited at five time intervals, 15 min apart, with an artificial palate in ...

We demonstrate a marked effect of prior adaptation upon the perceived position of subsequently presented stimuli using both first-order (luminance-defined) and second-order (texture-defined) stimuli. The effect of varying the contrast of the adapting and test stimuli depends only upon the ratio of adapting/test contrast. Adaptation effects for the two types ...

Many tissues and cells adapt to their mechanical environment, i.e. the stresses and strains to which the tissues are exposed during daily activities. Simple mechanical explanations of such adaptation naturally provide appeal, yet fail to predict accurately tissue appearance and behaviour. Continuum mechanics, the field from which our concepts of ...

There are marked similarities in the adaptation to motion observed in wide-field directional neurons found in the mammalian nucleus of the optic tract and cells in the insect lobula plate. However, while the form and time scale of adaptation is comparable in the two systems, there is a difference in ...

Caenorhabditis elegans uses a variety of attractive olfactory cues to detect food. We show here that the responses to olfactory cues are regulated in a dynamic way by behavioral context and the animal's previous experience. Prolonged exposure to an odorant leads to a decreased response to that odorant, a form ...

The time course and extent of brightness fading in a Ganzfeld were determined for adapting luminances ranging from 0.01 to 100 cd/m2. Magnitude estimation and interocular brightness matching were used. During Ganzfeld adaptation, perceived brightness decreased slowly and leveled off, on average, after 5-7 min (adapting time increasing with luminance). ...

Spontaneous perceptual change was studied by measuring the probabilities of the first two spontaneous pattern switches as a function of time following the onset of a bistable apparent quartet for which either horizontal or vertical motion is perceived. Contrary to the classical satiation hypothesis (Köhler & Wallach, 1944), differential time-dependent ...

Simple loudness adaptation for pure tones was measured at frequencies from 0.125 to 16 kHz and at sensation levels from 5 to 60 dB. Sixteen young listeners with normal hearing participated in four experiments. Most of the loudness measurements were obtained by the method of successive magnitude estimation; some were ...

Owing to the limited dynamic range of a neuron's output, neural circuits are faced with a trade-off between encoding the full range of their inputs and resolving gradations among those inputs. For example, the ambient light level varies daily over more than nine orders of magnitude, whereas the firing rate ...

Alpha ganglion cells from the midperiphery of the rabbit retina were recorded intracellularly under visual control, in a superfused everted eyecup, and labeled with HRP. Their physiology and large somata with broad dendritic arbors identified them as uniform populations of ON- and OFF-center alpha ganglion cells, which typically displayed transient/sustained ...

Several animal studies have shown an anatomical and functional separation between the ON- and OFF-pathways in the retina and in the lateral geniculate nucleus. Psychophysical studies in humans have also documented separate pathways that process increments and decrements of light. However, at the level of the visual cortex, there is ...

The ability of scallop hyperpolarizing photoreceptors to respond without attenuation to repetitive flashes, together with their low light sensitivity, lack of resolvable quantum bumps and fast photoresponse kinetics, had prompted the suggestion that these cells may be constitutively in a state akin to light adaptation. We here demonstrate that their ...

The degree of adaptation and the time course of recovery after adaptation to NaCl solutions of various intensities were examined by magnitude estimation and simple sensory reaction time using a test stimulus of constant intensity. The results show that the degree of adaptation increased with the adapting concentration following a ...

Adaptation of perceived movement during head motion (apparent concomitant motion, ACM) and the subsequent elimination of adaptation were studied in two experiments. During the adaptation phase of both experiments, subjects performed voluntary 1-Hz head oscillations for 6 min while fixating a stimulus moving either in the same (with) direction as ...

The recent surge in knowledge of cellular and molecular mechanisms of intestinal sugar transport has fueled an enormous interest in adaptive mechanisms regulating sugar transport. We first review several functional considerations that help us interpret the different patterns of adaptation for different nutrients. We then distinguish nonspecific adaptive mechanisms leading ...

The effects of weightlessness on vestibular function have been studied since the beginning of manned spaceflight. The results of these studies have been highly variable and to some extent even contradictory, which makes it difficult to draw unambiguous conclusions. This variability is probably due to at least three factors: (1) ...

Light-induced changes in the input resistance (Rin) of external, luminosity (i.e. H1) type horizontal cell (HC) perikarya were studied by the bridge-balance method in light-adapted and dark-adapted retinae of carp. Changes in input resistance (delta Rin) induced by short-(460 nm) and long-wavelength (674 nm) flashes, adjusted in intensity to elicit ...

A central unanswered question in phototransduction is how photosensitive molecules, visual pigments, regulate their absorption spectra. In nature, there exist various types of visual pigments that are adapted to diverse photic environments. To elucidate the molecular mechanisms involved in the adaptive selection of these pigments, we have to identify amino ...

Adaptations during phylogenesis or ontogenesis can occur either by maintaining constant or by increasing the informational content of the organism. In the former case the increasing adaptations to external perturbation are achieved by increasing the rate of genome replication; the increased amount of DNA reflects an increase of total but ...

On-line speaker adaptation is desirable for speech recognition dictation applications, because it o#ers the possibilityto improve the system with the speaker-speci#c data obtained from the user. Since the user will work with such a device over a long period, for a dictation system the long term speed. In contrast to ...

The threshold intensity for large-long incremental stimuli rises proportionally to adapting background luminance IB (Weber adaptation), but the intensity required to evoke a criterion high-brightness sensation rises much less steeply. We propose that this difference originates in the very first stage of visual processing, in the phototransduction and adaptation properties ...

Adaptation was studied in a paradigm in which the adapting stimulus was a variably biased version of a bistable apparent motion stimulus, a motion quartet, and the post-adaptation test stimulus was a "neutral" motion quartet. Either horizontal or vertical motion was perceived, never both at the same time. When only ...

The present report describes psychobiological studies of behavior around the time of birth. An adaptive, ecological perspective is presented in which stimulation of the fetus and newborn is purported to instigate adaptive postpartum behavior. Studies describing the perinatal sensory environment are reviewed, with a consideration of emergent sensory function of ...

A computational model is proposed to account for the adaptive properties of the fly motion system. The response properties of motion-sensitive neurons in the fly are modelled using an underdamped adaptive scheme to adjust the time constants of delay filters in an array of Reichardt detectors. It is shown that ...

Light adaptation in vertebrate photoreceptors is commonly attributed to a feedback mechanism that reduces the amplitude of the receptor potential by speeding the inactivation of the transduction cascade and hastening the recovery process. Recent studies have challenged this model and suggest instead that desensitization originates mainly from changes in the ...

We have measured the spread of contrast adaptation across the dimension of spatial frequency. Threshold elevation was tightly tuned to the adapting spatial frequency but became much broader as test contrast was increased. This means that, for a given test frequency, there are some frequencies which do not raise threshold ...

This report adds to existing evidence that a monocular, feature-sensitive motion mechanism is involved in two-dimensional (2-D) motion processing, and also accounts for an earlier, unexplained result [Alais et al.(1994) Vision Research, 34, 1823-1834]. The central finding is that the perceived direction of a monocularly viewed type II plaid changes ...

The application of an electronic real time emulator for biology-inspired pulse processing neural networks (BPN) to recognition and temporal tracking of discrete impulse patterns via delay adaptation is demonstrated. The electronic emulation includes biologically plausible features, such as asynchronous impulses, membrane potentials and adaptive weights, as well as a mechanism ...

Cross-adaptation, the decrease in sensitivity to one odorant following exposure to a different odorant, is affected by odorant similarity, both perceptual and structural, but the precise relationship is obscure. The present series of studies was designed to explore various aspects of perceptual and structural similarity as they relate to cross-adaptation. ...

Adapting to a chromatic light can alter the color appearance of other lights in view. The chromatic adapting effect is measured here with the test and adapting field perceived in the same depth plane, or perceived in different depth planes (using stereo disparity). The measurements show only a weak, though ...

The importance of the pattern of light stimulus in inducing light-adaptive morphological (cellular and sub-cellular) changes in the outer retina of the carp was assessed. Thus, the effects of steady and flickering backgrounds (of the same intensity) on cone photomechanical movements (PMMs) and horizontal cell (HC) spinules were compared by ...

Respiratory sensation was studied in seven European lowlanders during a Himalayan expedition at over 6000 m. At rest, the ability to detect added inspiratory resistive loads can be used to create a sensitivity index P(A) taking response bias (B) into account based on Sensory Decision Theory. The data indicate that ...

We propose a Boolean cellular automation to model an artificial adaptive living organism in order to investigate the development of cyclic vital functions during a simulated evolutionary process. The organism is endowed with a basic architecture consisting of several sensor (input), motor (output) and processing Boolean gates whose connectivity pattern ...

Modulation of stimulus luminance in a tachistoscopic face discrimination task has been found to significantly invert visual hemifield advantage in reaction time (RT) (Sergent, 1982a, Sergent, 1982b). However, there is no more physiological rationale for that than for a similar effect, say, of retinal adaptation, and it is even conceivable ...

Changes in latency of evoked potentials (EP) may indicate clinically and diagnostically important changes in the status of the nervous system. A low signal-to-noise ratio of the EP signal makes it difficult to estimate small, transient, time-varying changes in latency, or delays. Here, we present an adaptive algorithm that estimates ...

Brightness of uniform fields during normal and stabilized viewing was determined as a function of adapting luminance, field size, and luminance gradient of the edges of the adapting field. In one set of experiments, it was found that, over a range of adapting luminances from 6 to 9600 td, a ...

This brief essay explores some of the subtler ramifications of the notion of order or information. It starts out by arguing that and why a system's information or order must be one of the central determinants of its power and productivity, hence of its capacity to survive. Furthermore, such information ...

When bowel is lost due to disease or surgery, the residual bowel increases its functional capacity in order to compensate for the loss of absorptive capacity. The success and extent of this adaptive process is critical to recovery. This article reviews the current understanding of the intestinal adaptation. Adaptation is ...