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At least 991 records · Page 55Linked to original sources
PubMed1981

Effects of stimulus frequency, level, and duration on auditory temporal ordering.

Auditory temporal ordering was investigated in 5 normal-hearing young adults. Ss made diotic 2IFC judgments for pure tones of 0.5, 1, 2, or 4 kc/s and critical-band noises centered at those frequencies, on duration (standard: 40 msec; variables: 10, 20, or 30 msec), level (standard: 70 db HL; variables: 40, 50 or 60 HL), and frequency (standard: 0.5 kc/s; variables: 1,2, or 4 kc/s). Interstimulus interval (ISI) was 5, 10, 20, 50, 100, or 200 msec. All stimuli were at 70 db HL except of course the variable stimuli in the level judgments. Performance improved with increasing ISI. Mean threshold ISIs (performance at 75%-correct) collapsed across pure tones and noise bands were 12.5, 6.25, and 6.25 msec for duration, level, and frequency, respectively. With ISI constant at 100 msec, ANOVAs revealed statistically significant differences among the variables for duration and for level but not for frequency (performance for frequency was nearly perfect at the shortest ISI). There were statistically significant differences between mean performance, and between mean threshold ISIs, for duration, level, and frequency, indicating that auditory temporal acuity is not independent of the kinds of sound, as has been suggested (Hirsh, J. Acoust. Soc. Am., 1959, 31, p. 759).

Adult↗
PubMed1980

A developmental study of interhemispheric transfer in children aged five to ten.

In light of anatomical evidence that the corpus callosum does not become fully mature until about age 10, the present study attempted to find evidence of a developmental increase in the efficiency with which information is transferred between the 2 hands (hemispheres). Children were tested at ages 5, 7, and 9 on a battery of 4 tasks which measured the interhemispheric transfer of information necessary to (1) perform a simple size discrimination, (2) reproduce a temporal pattern, (3) reproduce a linear motor movement, and (4) reconstruct a 2-dimensional spatial pattern. All tasks were performed without visual guidance and utilized unilateral tactual and/or kinesthetic input and a 1-handed response. 2 tasks--the motor movement task and the spatial pattern task--showed evidence of a developmental increase in interhemispheric transfer, but the developmental pattern seen on these 2 tasks differed. Possible reasons for the between-task differences are discussed as well as their possible developmental implications.

Cerebral Cortex↗
PubMed1994

[How do we read? Study of eye movement in reading].

Reading associates a perceptive time, a motor time and a cognitive time, all three phenomena being extremely interdependent. After a review of the physiological mechanisms of reading, the authors discuss, on the basis of experimentation in the normal subject, the results of a study involving electro-oculographic recording of reading.

Adult↗
PubMed1993

Spatiotemporal observation of guinea pig auditory cortex with optical recording.

The spatiotemporal characteristics of neural activity in the guinea pig auditory cortex were studied in order to clarify neural processing and coding mechanisms of complex sounds. We used a multi-channel optical recording system for a voltage-sensitive dye: RH795. The experimental results showed that a boomerang-shaped moving pattern of optical response appeared on the cortical surface in response to complex sounds (clicks) stimulation, but a rather fixed pattern appeared in response to tone burst stimulation. The tonotopical organization observed using microelectrode was not directly visible, but a similar topographic pattern was evidenced by selecting regions of a strong response evoked by tone-bursts. The correlative functions of regionwide responses may indicate a parallel and serial neural processing structure.

Acoustic Stimulation↗
PubMed1993

Two-dimensional spatiotemporal coding of linear acceleration in vestibular nuclei neurons.

Response properties of vertical (VC) and horizontal (HC) canal/otolith-convergent vestibular nuclei neurons were studied in decerebrate rats during stimulation with sinusoidal linear accelerations (0.2-1.4 Hz) along different directions in the head horizontal plane. A novel characteristic of the majority of tested neurons was the nonzero response often elicited during stimulation along the "null" direction (i.e., the direction perpendicular to the maximum sensitivity vector, Smax). The tuning ratio (Smin gain/Smax gain), a measure of the two-dimensional spatial sensitivity, depended on stimulus frequency. For most vestibular nuclei neurons, the tuning ratio was small at the lowest stimulus frequencies and progressively increased with frequency. Specifically, HC neurons were characterized by a flat Smax gain and an approximately 10-fold increase of Smin gain per frequency decade. Thus, these neurons encode linear acceleration when stimulated along their maximum sensitivity direction, and the rate of change of linear acceleration (jerk) when stimulated along their minimum sensitivity direction. While the Smax vectors were distributed throughout the horizontal plane, the Smin vectors were concentrated mainly ipsilaterally with respect to head acceleration and clustered around the naso-occipital head axis. The properties of VC neurons were distinctly different from those of HC cells. The majority of VC cells showed decreasing Smax gains and small, relatively flat, Smin gains as a function of frequency. The Smax vectors were distributed ipsilaterally relative to the induced (apparent) head tilt. In type I anterior or posterior VC neurons, Smax vectors were clustered around the projection of the respective ipsilateral canal plane onto the horizontal head plane. These distinct spatial and temporal properties of HC and VC neurons during linear acceleration are compatible with the spatiotemporal organization of the horizontal and the vertical/torsional ocular responses, respectively, elicited in the rat during linear translation in the horizontal head plane. In addition, the data suggest a spatially and temporally specific and selective otolith/canal convergence. We propose that the central otolith system is organized in canal coordinates such that there is a close alignment between the plane of angular acceleration (canal) sensitivity and the plane of linear acceleration (otolith) sensitivity in otolith/canal-convergent vestibular nuclei neurons.

Acceleration↗
PubMedDate not supplied

[The electroencephalographic correlates of the intellectual abilities of adolescents].

Analysis of correlation between intellectual faculties of schoolchildren and spatiotemporal organization of their brain electrical activity was carried out. The less intelligent teen-agers showed more expressed alpha-activity in the EEG of rest, higher level of EEG coherence, and insignificant restructuring of the rhythmical activity under conditions of "open eyes" as compared with the "closed eyes". In the resting EEG of highly intelligent teen-agers beta-frequencies were more expressed and desynchronization after opening the eyes was clearly detectable.

Adolescent↗
PubMed1997

Retooling Social Security for the 21st century.

Because of the imbalance between promised benefits and available taxes, some reform of Social Security is inevitable. At the same time, perceptions of Social Security are changing rapidly as it moves away from a system where all recipients--whether rich or poor--received more in benefits than they paid in taxes, and where those who were richer consistently received larger net transfers than those who were poorer. Reform is most likely to succeed if it returns to basic principles such as progressivity, equity, and efficiency. Although these principles sometime conflict, they also provide much common ground. For example, if Social Security is meant to meet the greatest needs of the elderly, then increasing the retirement age (which mainly affects the younger and richer elderly) would be preferable to removal of the cost-of-living adjustment (which mainly affects the older and poorer elderly). Efficiency and equity principles, in turn, call attention to some groups--second earners in households, those with few employee tax preferences, those who work many years, and elderly workers--whose net benefits are lower than others who should have less claim to Social Security resources.

Aged↗