Discrimination of Velocity and Spectral Composition of a Sound Stimulus during Its Movement in the Vertical Plane

Differential sensitivity to the velocity of a sound source image in the vertical plane was studied by using two signals with different spectral bandwidths: 0.25–4 kHz (signal 1) and 4–12.5 kHz (signal 2). Five subjects were tested. Sequential switching of loudspeakers with similar frequency characteristics simulated movement of a sound source. Differential velocity thresholds were determined for two reference velocities: 58 and 115°/s. Significant differences in the absolute values of these thresholds were found for signals with different spectral compositions. The threshold for signal 1 (0.25–4.0 kHz) exceeded that for signal 2 (4.0–12.5 kHz) twofold at 58°/s and 1.6-fold at 115°/s.     

The subjective auditory space of epileptic patients with lesions in both the temporal cortical area and the hippocampus

Parameters of the subjective auditory space formed under the conditions of dichotic stimulation during movement of the acoustic image in different directions were studied in 13 epileptic patients with lesions in both the temporal cortex and the hippocampus. The pattern and degree of the movement trajectory of the subjective acoustic image (SAI) were determined in two groups of patients (in seven patients with the right-side focus and six patients with the left-side focus of convulsive activity, depending on the direction of moving and the initial interauricular delay (700, 400, and 200 μs)). A significant decrease in the SAI movement trajectory was observed in patients with right-or the left-side lesions in the temporal cortex and hippocampus as compared to healthy subjects or patients with temporal cortical epilepsy in the cases when the SAI movement stopped at the side of the epileptic focus. The analysis of the parameters of the SAI movement in each hemisphere showed a highly significant difference between the movement trajectories for all values of initial delays as compared to the control group of healthy subjects (p < 0.01) and patients with a relatively isolated lesion of the right temporal cortex (p < 0.05). A significant role of the epileptic lesion of the hippocampus (which is not an auditory structure) in the impairment of spatial hearing was demonstrated. The characteristics of the functional asymmetry because of simultaneous epileptic lesion of the temporal cortex and hippocampus, which led to the impairment of the binaural effect, are discussed.     

Effect of the human cumulus oophorus on movement characteristics of human capacitated spermatozoa

The effect of human cumulus oophorus on movement characteristics of human spermatozoa previously incubated in vitro under capacitating conditions was studied using automated digital image analysis. When spermatozoa were incubated for a short time with whole cumuli, most of those that penetrated the cumulus intercellular matrix were characterized by a linear movement with small amplitudes of lateral head displacement, but with elevated values of beat cross frequency. Short (5 min) incubation with solubilized cumulus intercellular matrix of spermatozoa preincubated in capacitating conditions (6 h) significantly reduced the percentage of spermatozoa showing the 'hyperactivated' type of motility characterized by high curvilinear velocity, low progressive velocity and elevated values of lateral head displacement. Moreover, a subpopulation of spermatozoa with very high values of progressive velocity and beat cross frequency and with reduced amplitudes of lateral head displacement appeared in these conditions. This cumulus-related motility pattern was not seen in fresh spermatozoa or in those incubated in the absence of cumulus material. Changes in the sperm movement characteristics similar to those observed in the presence of the solubilized cumulus matrix could also be induced by some of its h.p.l.c. fractions. These results show that the intercellular matrix of the human cumulus oophorus exerts a specific effect on human sperm motility, probably acting preferentially on the 'hyperactivated' sperm subpopulation.     

Evoked potentials of the cat inferior colliculus to acoustic stimuli simulating sound source movement with different velocities in opposite directions

Amplitude changes of inferior colliculus evoked potentials (EPs) in anaesthetized adult cats were studied under presentation of acoustic stimuli simulating both azimuth-moving and stationary sound source. The movement was simulated with gradual changes of interaural time delay between binaurally presented click trains. It was shown that the amplitude of EPs elicited by "moving" signals depended on the velocity of movement. Amplitude differences between EPs to "moving" and stationary stimuli were observed under motion velocities up to 320 deg./s. The greatest response amplitudes in different experiments took place under velocities within the range of 67-320 deg./s with most of them recorded under velocities of 170 and 125 deg./s. Amplitude of the responses to lateral-medial movement with any velocity were always greater than those to opposite direction of movement with the same velocity.     

A sensory map based on velocity threshold of sensory neurones from a chordotonal organ in the tailfan of the crayfish

The central projections of sensory neurones innervating a strand chordotonal organ (CO) in the tailfan of the crayfish, Procambarus clarkii (Girard) have been investigated. The CO monitors movement of the exopodite of the tailfan relative to the endopodite. Intracellular recording and staining were used to characterise the response of the sensory neurones to applied stretches of the chordotonal organ and to reveal their morphology. Two gross morphological types of afferents were found: those that terminated in the terminal (6th) abdominal ganglion on the side ipsilateral to the sensory receptor, and those that had branches in the terminal ganglion and an intersegmental axon that ascended rostrally. Afferents responded to position, velocity and direction of imposed CO displacement. Afferents with particular physiological properties had similar morphologies in different crayfish. Irrespective of their directional responses, afferents had central projection areas dependent upon their velocity thresholds. Many afferents responded only during movement of the CO, and those with the lowest velocity thresholds (2°/s) had branches that projected most anteriorly, while those with progressively higher velocity thresholds (up to 200°/s) projected progressively more posteriorly. Afferents that responded to low velocity ramp movements and spiked tonically projected to more posterior areas of the ganglion than those that responded only to movements.Abbreviations A6SCI sixth abdominal sensory commissure I - CO chordotonal organ - DMT dorsal medial tract - G6 sixth abdominal ganglion - LDT lateral dorsal tract - MDT medial dorsal tract - MVT medial ventral tract - R1–4 nerve roots 1–4 - VLT ventral lateral tract - VMT ventral medial tract     

Critical threshold effects of benthiscape structure on stream herbivore movement

In landscape ecology, substantial theoretical progress has been made in understanding how critical threshold levels of habitat loss may result in sudden changes in landscape connectivity to animal movement. Empirical evidence for such thresholds in real systems, however, remains scarce. Streambed landscapes provide a strong testing ground for studying critical thresholds because organisms are faced with substantial environmental heterogeneity while attempting to overcome the physical force of water. In this study, I report on the results from a series of experiments investigating the influence of habitat abundance and current velocity on the movement dynamics of two stream herbivores (caddisfly larva Agapetus boulderensis and snail Physa sp.) that differ substantially in how they perceive landscape structure. Specifically, I ask whether critical thresholds to herbivore movement exist in streambed landscapes. By exploiting the pattern recognition capabilities of artificial neural networks, I found that the rate, sinuosity and directionality of movement by Agapetus and Physa varied nonlinearly according to the abundance of habitat patches, current velocity and habitat-current interaction. Both the study organisms exhibited threshold responses to habitat abundance, yet the location and slope of these thresholds differed between species and with respect to different current velocities. These results suggest that a critical threshold in functional connectivity (i.e. the connection of habitat patches by dispersal) is not an inherent property of the landscape, but in fact emerges from the interplay of species' interactions with landscape structure. Moreover, current velocity interacted with habitat abundance to elicit strong upstream-oriented movement for both the species. This suggests that dispersing individuals may be polarized in the upstream direction and therefore functional connectivity is not equal in all directions. Such results highlight the need for future research addressing the sources of variability of critical threshold effects in ecological phenomena.     

Unit activity in the superior colliculus of the cat following passive eye movements.

Unit response in the superior colliculus and underlying structures has been examined in the choralose-anaesthetized cat following passive movement of an occluded eye. One group of units was sensitive to small saccadic movements, responded regardless of the initial postion of the eye, and in most instances responded to movements in opposit directions. A second numerically smaller group also responded when they eye was moved at saccadic velocity but only when the eye passed a fixed point. Such units with fixed positional thresholds were found following movements in both nasal and temporal directions as well as to both upward and downward movement. Both types of unit response were found after transection of the optic nerve and were also recorded when individual extraocular muscles were subjected to controlled stretch. It is assumed that most unit activity seen after passive movement of the occluded eye is due to activity in extraocular muscle receptors. In the deep layers of the superior colliculus responses to small eye movements were found to be due to the activation of very low threshold receptors sensitive to vibration in the facial area.     

Muscle-contraction properties in overarm throwing movements

On the basis of dynamic and kinematic data, this study identifies the type of muscle contraction in unloaded overarm throwing movements. An unloaded throw or nearly unloaded throw is defined as the throw in which the external resistance is too small (e.g., the team handball, baseball, and water polo throws as well as the tennis and badminton smashes). A special arm-force-measuring apparatus was constructed to imitate an overarm throw. Forty-two subjects were placed into 3 groups: untrained subjects, weight-trained athletes, and team handball players. The measured parameters included the velocity of the initial movement, the release velocity, the velocity of the first 50 milliseconds of the concentric phase, the force value at the moment of deceleration of the initial movement, and the impulse values during the eccentric and concentric phases of the test movement. Statistically significant higher values of the above parameters (p < 0.05) were determined in that test at which the initial speed of movement was higher. Also, the correlation coefficients of the parameters of the initial phase of the throw movement were very high (p < 0.001), especially the parameters related with the movement's first 50 milliseconds. The results support the thesis that the stretch-shortening cycle is the type of muscle contraction in unloaded overarm throws. Furthermore, it is possible to increase the throw velocity by increasing the velocity of the initial movement (i.e., by provoking higher inertia forces).     

Evoked Potential Audiograms of the Nurse Shark (Ginglymostoma cirratum) and the Yellow Stingray (Urobatis jamaicensis)

The hearing thresholds of the nurse shark, Ginglymostoma cirratum, and the yellow stingray, Urobatis jamaicensis, were measured using auditory evoked potentials (AEP). Stimuli were calibrated using a pressure-velocity probe so that the acoustic field could be completely characterized. The results show similar hearing thresholds for both species and similar hearing thresholds to previously measured audiograms for the lemon shark, Negaprion brevirostris, and the horn shark, Heterodontis francisi. All of these audiograms suggest poor hearing abilities, raising questions about field studies showing attraction of sharks to acoustic signals. By extrapolating the particle acceleration thresholds into estimates of their equivalent far-field sound pressure levels, it appears that these sharks cannot likely detect most of the sounds that have attracted sharks in the field.     

Acoustic microscope study of the elastic properties of fluorapatite and hydroxyapatite, tooth enamel and bone.

Measurements of Rayleigh velocity and attenuation were taken in single mineral crystals of hydroxyapatite and fluorapatite at angular intervals relative to their c axes, using an acoustic microscope. These results are compared with the values that were calculated using the elastic constants of apatite from Yoon and Newnham [(1969) Am. Miner. 54, 1193-1197.] and Katz and Ukraincik [(1971) J. Biomechanics 4, 221-227.]. The slowness curves of various wave modes are plotted and discussed in relation to cross-coupling effects that were found to cause instability in measurements of attenuation for the c axes direction. Velocity measurements were taken in specimens of tooth enamel and bone. Here comparisons are made with the values that were calculated by modelling the 'z' scan response of the microscope, using published data for the elastic and acoustic properties. Comparisons are also made with the measurements on single crystals, since apatite is a major component of enamel and bone.     

Various characteristics of the control of cyclic movements

It was shown by studying control forces and phasic trajectories during oscillation of human forearm, locomotion and rocking of the body on the support that there was an image of accomplished movement in the central nervous system. This image seems to be realized by linear connected displacements of the muscle tension level and threshold of tonic stretch reflex. During the control process, velocity of the threshold and tension level is similarly transformed to that of the body part. The piece constant similarity coefficient is regulated centrally. The main result of such control is moving of the body along energy optimal trajectories.     

Long-lasting inhibition of the soleus muscle H reflex related to realization of voluntary arm movements in humans

In healthy humans, we recorded the H reflex induced by transcutaneous stimulation of the tibial nerve (recording from the soleus muscle). In subjects in the lying position, we studied changes in the H reflex values after preceding voluntary arm movements realized with a maximum velocity after presentation of an acoustic signal. On the 200th to 300th msec after forearm flexion, long-lasting inhibition of the H reflex developed following a period of initial facilitation and reached the maximum, on average, 700 msec from the moment of the movement. Flexion of the contralateral upper limb in the elbow joint induced deeper inhibition than analogous movement of the ipsilateral arm. Long-lasting clear inhibition of the H reflex developed after arm flexion in the elbow joint but was slightly expressed after finger clenching. After inhibition reached the maximum, its time course was satisfactorily approximated by a logarithmic function of the time interval between the beginning of the conditioning voluntary movement and presentation of the test stimulus. Durations of inhibition calculated using a regression equation were equal to 6.6 sec and 8.5 sec after ipsilateral and contralateral elbow-joint flexions, respectively. Inhibition was not eliminated under conditions of tonic excitation of motoneurons of the tested muscle upon voluntary foot flexion. Long-lasting inhibition of the H reflex was also observed after electrical stimulation-induced flexions of the upper limb. The obtained data indicate that movements of the upper limb cause reflex long-lasting presynaptic inhibition of the soleus-muscle H reflex that can play a noticeable role in redistribution of the muscle tone during motor activity. Neirofiziologiya/Neurophysiology, Vol. 40, No. 3, pp. 221–227, May–June, 2008.     

Ample active acoustic space of a frog from the South American temperate forest

The efficiency of acoustic communication depends on the power generated by the sound source, the attributes of the environment across which signals propagate, the environmental noise and the sensitivity of the intended receivers. Eupsophus emiliopugini, an anuran from the temperate austral forest communicates by means of an advertisement call of moderate intensity within the range for anurans. To estimate the range over which these frogs communicate effectively, we conducted measurements of call sound levels and of auditory thresholds to pure tones and to synthetic conspecific calls. The results show that E. emiliopugini produces advertisement calls of about 84 dB SPL at 0.25 m from the caller. The signals are affected by attenuation as they propagate, reaching average values of about 47 dB SPL at 8 m from the sound source. Midbrain multi-unit recordings show quite sensitive audiograms within the anuran range, with thresholds of about 44 dB SPL for synthetic imitations of conspecific calls, which would allow communication at distances beyond 8 m. This is an extended range as compared to E. calcaratus, a related syntopic species for which a previous study has shown to be restricted to active acoustic spaces shorter than 2 m. The comparison reveals divergent strategies for related taxa communicating amid the same environment.     

Effects of passive and active movement on vibrotactile detection thresholds of the Pacinian channel and forward masking

Abstract

We investigated the gating effect of passive and active movement on the vibrotactile detection thresholds of the Pacinian (P) psychophysical channel and forward masking. Previous work on gating mostly used electrocutaneous stimulation and did not allow focusing on tactile submodalities. Ten healthy adults participated in our study. Passive movement was achieved by swinging a platform, on which the participant’s stimulated hand was attached, manually by a trained operator. The root-mean-square value of the movement speed was kept in a narrow range (slow: 10–20?cm/s, fast: 50–60?cm/s). Active movement was performed by the participant him-/herself using the same apparatus. The tactile stimuli consisted of 250-Hz sinusoidal mechanical vibrations, which were generated by a shaker mounted on the movement platform and applied to the middle fingertip. In the forward-masking experiments, a high-level masking stimulus preceded the test stimulus. Each movement condition was tested separately in a two-interval forced-choice detection task. Both passive and active movement caused a robust gating effect, that is, elevation of thresholds, in the fast speed range. Statistically significant change of thresholds was not found in slow movement conditions. Passive movement yielded higher thresholds than those measured during active movement, but this could not be confirmed statistically. On the other hand, the effect of forward masking was approximately constant as the movement condition varied. These results imply that gating depends on both peripheral and central factors in the P channel. Active movement may have some facilitatory role and produce less gating. Additionally, the results support the hypothesis regarding a critical speed for gating, which may be relevant for daily situations involving vibrations transmitted through grasped objects and for manual exploration.     

Movements of bonnetheads, <Emphasis Type="Italic">Sphyrna tiburo</Emphasis>, as a response to salinity change in a Florida estuary

The movement of bonnetheads, Sphyrna tiburo, within an estuarine system on the Gulf of Mexico coast of Florida was examined to define response to salinity change. Shark presence and movements were evaluated by acoustic monitoring and gillnet sampling. Acoustic monitoring data were used to investigate active selection of different zones within the estuary based on differences in salinity among zones. Sharks were monitored for 187 days in 2003 and 217 days in 2004 in salinities ranging from 11.0 to 31.0 ppt in 2003 and 15.8 to 34.6 ppt in 2004. Monitoring data supported the hypothesis that salinity played a role in the distribution and movement of S. tiburo. Catch per unit effort (CPUE) data obtained from gillnet sampling from 1995 to 2004 were examined to determine affinity or avoidance of specific salinities within the study site as calculated using an electivity index. Electivity analysis showed almost no affinity or avoidance for specific salinity values. The difference in results between the CPUE and acoustic monitoring in relation to the potential effects of salinity likely relate to the nature of the data, with acoustic monitoring providing continuous data and CPUE providing snapshot location data. The results of this study suggest that although S. tiburo are collected within a wide range of salinity levels, salinity may affect movement and distribution. Salinity effects may be more pronounced during periods of prolonged and/or large changes in salinity as detected by long-term monitoring.     

Analysis of fragmented images perception: local features and global description

Analysis of experimental investigations of the perception of incomplete images is presented. It illustrates two different approaches to work of the brain mechanisms involved: one approach is based on the perception of whole images and another on local informative features. These approaches describe two different mechanisms, which are possibly used by brain systems for incomplete image recognition. Performance on the Gollin test (measuring recognition thresholds for fragmented line drawings of everyday objects and animals) depends upon recognition based on image informational-statistical characteristics. We suggest that recognition thresholds for Gollin stimuli in part reflect the extraction of signal from noise. The brain uses local informative features as an additional source of information about them. We have suggested that fragmented images in the Gollin-test are perceived as whole structures. This structure is compared with a template in memory which is extracted with the help of selective attention mechanism in accordance with a matched filtration model. The Gollin-test is a tool for differential diagnosis of a various forms of cognitive disorders.     

Analysis of acoustic stimulus to Liriomyza trifolii (Diptera: Agromyzidae) through Electroantennogram (EAG) technique

The study utilized the Electroantennogram (EAG) technique as biological acoustic stimulus to Liriomyza trifolii (Diptera: Agromyzidae). Pure tone sounds and courtship songs were tested in the excised head of test specimens. Significant EAG stimuli were detected when released at 20 Hz pure tone sound together with the courtship song having long pulse train patterns of Cryptonevra inquilina and Lipara japonica (Chloropidae). For their biological effectiveness, movement behaviors were analyzed with stimulus taken from EAG recordings. No attraction effect was observed even with and without acoustic stimulus. However, movement activities were transformed by information entropy and observed to be clearly different when selected acoustic stimuli were broadcast. The combination of response to EAG and behavioral observation would be useful to determine effective movement modification through acoustic stimulus in insect pests that are necessary toward the development of an acoustic pest management tool in agriculture.     

DNA image cytometry in the differential diagnosis of endometrial hyperplasia and adenocarcinoma

OBJECTIVE: To test the value of DNA image cytometry in the differential diagnosis of hyperplastic endometrial lesions and endometrial carcinoma on a series of 153 cases of simple hyperplasia (n = 71), complex hyperplasia (n = 28), complex atypical hyperplasia (n = 11) and endometrial adenocarcinoma (n = 43). STUDY DESIGN: Monolayer smears were prepared from three 50-micron-thick sections by a cell separation technique and were stained according to Feulgen. The DNA content of 250 epithelial cells, chosen randomly, was determined using a TV image analysis system (CM-1, Hund, Wetzlar, Germany). The DNA content of 30 lymphocytes served as an internal standard for the normal diploid value in every case. Different DNA cytometric parameters and the mean nuclear area were calculated. RESULTS: Cases of adenocarcinoma and complex atypical hyperplasia (n = 54) were defined as clinically "positive" as these patients are normally treated by hysterectomy. The remaining cases of simple and complex hyperplasia (n = 99) were interpreted as clinically "negative" as conservative therapy is usually preferred. Requesting a specificity of > 90%, high sensitivity rates were calculated for ploidy imbalance (94%), mean ploidy (91%), diploid deviation quotient (91%), DNA stemline ploidy (87%) and 2c deviation index (85%), based on suitable thresholds. Entropy (76%), 5c exceeding events (63%), mean nuclear area (48%) and 9c exceeding events (6%) revealed lower sensitivity values. 5c Exceeding events (P = .0117) and mean nuclear area (P = .0392) were helpful in differentiating between atypical hyperplasia and endometrial carcinoma as the data distribution was significantly different with the U test. CONCLUSION: Our results indicate that DNA single cell cytometry is a highly relevant tool in the differential diagnosis of endometrial lesions and could be used as a complementary diagnostic method, especially in histomorphologically difficult cases.