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Results for “Information Processing”

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At least 1,045 records · Page 58Linked to original sources
PubMed1977

Primate information processing under sodium pentobarbital and chlorpromazine: differential drug effects with tachistoscopically presented discriminative stimuli.

Sodium pentobarbital and chlorpromazine were evaluated for the degree to which they differentially reduce the speed or efficiency with which sensory information can be processed. Rhesus monkeys were tested under comparable doses of sodium pentobarbital and CPZ on a visual discrimination problem with varying durations of tachistoscopically presented stimulus information. When unlimited stimulus information was available, no effects of the two drugs were observed at the doses used, but as the duration of stimulus presentation was progressively decreased, the effects of sodium pentobarbital became more severe, whereas CPZ did not differe from the saline control an any presentation duration. While previously published literature indicates that CPZ impairs performance by intermittantly blocking sensory input or transmission, the present data provide the first direct behavioral confirmation that barbiturates impair performance by retarding the rate at which sensory stimuli can be processed and utilized.

Animals↗
PubMed1985

Image gathering and processing: information and fidelity.

In this paper we formulate and use information and fidelity criteria to assess image gathering and processing, combining optical design with image-forming and edge-detection algorithms. The optical design of the image-gathering system revolves around the relationship among sampling passband, spatial response, and signal-to-noise ratio (SNR). Our formulations of information, fidelity, and optimal (Wiener) restoration account for the insufficient sampling (i.e., aliasing) common in image gathering as well as for the blurring and noise that conventional formulations account for. Performance analyses and simulations for ordinary optical-design constraints and random scenes indicate that (1) different image-forming algorithms prefer different optical designs; (2) informationally optimized designs maximize the robustness of optimal image restorations and lead to the highest-spatial-frequency channel (relative to the sampling passband) for which edge detection is reliable (if the SNR is sufficiently high); and (3) combining the informationally optimized design with a 3 by 3 lateral-inhibitory image-plane-processing algorithm leads to a spatial-response shape that approximates the optimal edge-detection response of (Marr's model of) human vision and thus reduces the data preprocessing and transmission required for machine vision.

Humans↗
PubMed2002

On spectroscopy, control, and molecular information processing.

Implementing a logic machine on a single molecule was recently discussed with experimental roadmarks. Lasers were used to control the input and sometimes also the output of information with additional processing done via inter- and intramolecular dynamics. We examine the special requirements for an experiment that mimics a logic circuit. We use two-photon processes as physical examples of our considerations and discuss both combinational and sequential logic machines.

Journal Article↗
PubMed1990

Information processing to rare and frequent warning stimuli in a C.N.V. paradigm.

Seven normal young men were submitted to standard and target paired auditory stimuli. The warning stimulus of paired tones informed subjects whether or not the impending unconditional stimulus implied a motor response. Subjects were instructed to execute the motor response at less one second after the unconditional stimulus occurrence, and were informed that the standard warning stimulus was always followed by an additional stimulus which confirmed its detection. Components of target warning and imperative stimuli responses presented a significant increase in amplitude with regard to evoked potential components elicited by standard warning and unconditional tones. P3 waves observed in response to standard warning and unconditional stimuli culminated over fronto-central cortex, while P3 of target warning and imperative tone responses peaked over centro-parietal cortex. These results suggest that manipulating warning stimulus significance by assigning to it a discriminative function, can modify processing of the information carried out by paired stimuli.

Acoustic Stimulation↗
PubMed1982

Evolution of aversive information processing: a temporal trade-off hypothesis.

There is often a temporal relation in survival probabilities in life-threatening situations such as predator-prey encounters. As a situation intensifies or becomes more immediately dangerous, reflex responses usually dominate behavior, resulting in there being less time available to gather information for more complex processing by higher brain substrates. The only information to form a memory of such a threatening experience may be some neural code for 'avoid' (or a negative emotional attribute) and the context in which the experience has occurred. Hence, memory for aversive experiences may be more labile while reflexive responses to danger become much less labile to experimental manipulation as the severity of the threat increases. Natural selection may have preferentially acted on escape and avoidance responses such that plasticity to make decisions concerning other options in increasingly dangerous arenas may be much more limited. The possibility that time becomes a trade-off in an organism's attempt to more fully evaluate characteristics of a perceived threat underlies the 'temporal trade-off hypothesis'.

Amygdala↗
PubMed1991

Haptic information processing in direct and indirect memory tests.

Effects of learning can show up in a direct, i.e., an explicit, way or they can be expressed indirectly, i.e., in an implicit way. It was investigated whether motor processes underlie effects of repetition priming in haptic information exploration. In the test phase, blindfolded subjects had to handle objects in order to answer questions as fast as possible about their properties (e.g., temperature, texture, weight, or form), exploring the object with their hands. Some of the objects were old ones (presented in a study phase); others were added as new objects to the test phase. In addition, recognition judgements were required. The results demonstrated reliable effects of repetition priming in terms of reaction times to old, in comparison with new, objects for subjects who had been treated the same way in the study phase (active touch). Passive touch at encoding or studying the names or the visible objects themselves did not lead to effects of repetition priming in the test phase. On the other hand, performing adequate hand movements during the study improved recognition memory. The role of motor processes in indirect and direct tests of memory is discussed and related to research on memory of action events.

Adult↗
PubMed1986

Information processing in magnetic resonance imaging.

Techniques of image processing have been developed for the extraction of information from magnetic resonance images. The response of nuclei to a sequence of magnetic stimulations has been modeled and used to predict the effects of changing magnetic resonance parameters on signal intensity. This allows the calculation of new images from a small set of acquired data without additional acquisition. These images can be used to predict the results of new imaging techniques before actual implementation and to simulate the effects of parameter variations which are unfeasible or impractical, such as variable field strength. New forms of representation, for example, a tissue type map in which each homogeneous tissue category has been identified and labeled, can be used for more direct interpretation.

Algorithms↗
PubMed1994

Complex information processing by the transmembrane signaling system involving G proteins.

Much of the information cells receive is transduced by a membranous signaling system that uses heterotrimeric guanine nucleotide binding proteins (G proteins) to functionally couple cell surface receptors to a variety of effectors. During recent years it has been shown that receptors, G protein alpha, beta and gamma subunits as well as effectors involved in this signaling system exhibit a remarkable structural diversity and that the interactions of these components display a bewildering complexity. Even though many questions remain to be answered, it is becoming obvious that G proteins form the basis of a complex membranous signaling network which allows the cell to coordinate and to process incoming signals already on the level of the plasma membrane.

Animals↗
PubMed1992

Informational processing of complex sound. III: interference.

In this study, theoretical results from information theory and detection theory are applied to provide a formal analysis of the interaction of target and context uncertainty on the discrimination of brief multitone sequences. The experiments employ a sample-discrimination task in which the performance of an ideal observer is held constant while the relative variability of the target sigmaT and context sigmaC is varied. Listener performance in these experiments was less than ideal but increased monotonically with sigmaT/sigmaC whether the task was to discriminate the frequency or the intensity of the target. Performance was also constant for a constant sigmaT/sigmaC regardless of the target's position in the sequence. The results are consistent with a class of models in which the decision variable is a weighted sum of the tone values comprising the sequence. Weighting functions computed from the trial-by-trial date suggest that limits in performance result from trial-by-trial variability in the weights. The decision variable also serves as the basis for an analysis in which performance is linearly related to the information rate of the context independent of target position or task. In this analysis, target and context uncertainty contribute additively to the overall uncertainty associated with the decision variable.

Adult↗