The Haptic Intensity Order Illusion Is Caused by Amplitude Changes

Thalamo-cortical mechanisms underlying changes in amplitude and frequency of human alpha oscillations

As one of the serial experiments on the osmotic constancy within the body, the effects of intraabdominal injection of the solutions which were prepared by combining different amounts and osmolarities on the contractile property of the lymph heart were investigated in the anaesthetized toad. The properties of the peritoneal surface, respectively sensitive to the change in the volume and osmolarity in the abdominal cavity, were examined with respect to the change in amplitude and in frequency of the mechanical properties of the lymph heart.1. The lymph heart activity is controlled essentially by the spinal cord, and hence the changes occurred were reflexive in nature, except for few cases of which change in lymph heart motility was supposed to be caused by a direct effect of the solution injected on the lymph heart muscle itself.2. Heterotonic solutions which were injected into the abdominal cavity caused the change in frequency of the rhythmical lymph heart activity. Hypertonic solutions affected more strongly than hypotonic solutions. The increase in the volume of the solutions injected resulted in the addition of the increase in amplitude. The amount exceeding about 3 ml was enough to generate the volumetric response. The change in frequency was equivalent to the osmoceptive response and the change in amplitude the volumoceptive response.Isotonic solutions, either electrolytic or nonelectrolytic, when the amount was excessive, caused only volumetric response.3. Volumoceptive response was occurred immediately after the procedure, while osmoceptive response was relatively delayed even under the condition capable of producing both responses. The change in osmotic pressure of the solutions injected resulted always in the change in frequency of the motility even if the solution was hypertonic or hypotonic. The functional distinction of the osmoceptive and volumoceptive properties on the peritoneal surface was evident.

Frequency-change in DPOAE evoked by 1 s/octave sweeping primaries in newborns and adults

This paper attempts to define acoustic properties of laterals in English that are adjacent to vowels and in syllabic nuclei. When the tongue is in the lateral configuration, there is an increased bandwidth and decreased prominence of the second formant (due to increased losses) and some irregularities in the F3–F4 region (divided acoustic path). When a lateral consonant is produced adjacent to a vowel, there is a rapid change in the acoustic spectrum as these attributes appear or disappear. A series of acoustic analyses has investigated the nature of this discontinuity, particularly the change in amplitude and frequency of the first two spectral prominences. An abrupt change in F2 amplitude of about 10 dB at consonant release (less at closure) is a salient attribute. The attributes that distinguish a syllabic lateral and a nonlow back vowel /o/ have been examined through acoustic analyses and through perceptual experiments in which F2 bandwidth and other properties are manipulated in synthetic utterances. F2 bandwidth again appears to play a significant role in signalling this distinction. The common acoustic attributes associated with the lateral configuration appear to be used in different ways by listeners depending on the context. [Research supported in part by NIDCD.]

The Fourier analysis of period histograms of spike discharges of single cochlear nerve fibers in response to continuous, single sinusoidal stimuli reveals properties that are remarkably similar to those of the cochlear microphonic (CM) as measured in individual turns of the cochlea. We compare phase shift, as a function of stimulus frequency, for the fundamental component of response of single fibers (as obtained by us) to that for the CM from different turns of the cochlea (from the literature). Curves from both sets of data can be closely approximated by two straight lines. The changes in slopes, and the positions of the break points of the straight line segments behave similarily with changes in characteristic frequency (CF) of the fibers (0.37–5.4 kHz) and changes in the frequency of maximum sensitivity of the CM. For both sets of data, intercepts of extrapolations of the straight lines depart from the origin; for one, as CF increases; for the other, as turn number decreases. Relative amplitudes of the fundamental and second and third harmonics versus stimulus level and versus stimulus frequency also behave in a manner similar to the corresponding CM measurements. These data, resulting from single sinusoidal stimuli, suggest that CM is closely associated with the mechanisms affecting the structure of the spike discharge trains sent to the brain. [This investigation was supported by PHS research grants from the National Institutes of Health.]

Infrared dielectric function of photochromic thiazolothiazole-embedded polymer

A dorsal column (DC) lesion has lasting effects on behavioral tasks that require temporal processing of tactile information (e.g., frequency and duration discrimination). The present experiments describe physiological correlates of these deficits in temporal discrimination. Compound action potentials evoked by electrocutaneous stimulation were recorded from the major white matter subdivisions of the spinal cord in anesthetized monkeys, and relationships between stimulation frequency and evoked potential (EP) amplitude were determined for the ascending pathways. At 10 pulses per second (Hz) EPs recorded in the lateral spinal columns were attenuated slightly (by 15% or less, relative to 1.5 Hz), whereas potentials recorded from the DCs were not attenuated. The attenuation increased with stimulation frequencies up to 50 Hz, reaching 80% for the anterolateral column and 38% for the dorsolateral column, but only 15% for the DC. Epidural EPs were recorded, before and after interruption of the contralateral DC, from awake animals with electrodes chronically implanted over primary somatosensory cortex (SI). Following the lesion. EP responses to 1.5-Hz stimulation were 46% of preoperative responses to the same stimulus. At 10 Hz, EP amplitudes were attenuated even more, to 27% of the preoperative amplitude at 1.5 Hz. Principal components analysis was employed to quantify alterations in EP conformation and stimulus frequency was varied from 1.5 to 10 Hz, before and after a DC lesion. Interruption of the DC resulted in a significant decrease in the information provided by the EP about changes in stimulus frequency. EPs were also recorded from different locations along the anterior-posterior dimension of the hindlimb region of SI in lightly anesthetized animals. Principal components analysis revealed that there was less information present in the EP about changes in stimulus frequency (1.5-10 Hz) at all recording locations in animals with a DC lesion, compared with the cortex of normal animals. The DC lesion significantly decreased the amplitude of cortical EPs evoked by repetitive stimulation. At 10 Hz the EP was nearly buried in noise, consistent with behavioral deficits in discrimination of the duration of 10 Hz stimulation following interruption of the DC. Also, significantly less information was present in the cortical EPs about changes in stimulus frequency in the absence of intact DCs, which is consistent with deficits in frequency discrimination. This reduction could be explained in part by a lesser capacity of spinal pathways in the lateral column to follow repetitive stimulation above 10 Hz. However, more rostral manifestations of a DC lesion, at either the thalamus or the cortex, are likely to contribute to the reduced capacity of animals with DC lesions to make temporal discriminations.

The orexin neuropeptide family consists of orexin-A and orexin-B, which are coded from the same prepro-mRNA. Although peripherally administered orexin-A abolishes small intestinal interdigestive contractions in rats, it still remains unclear whether orexin-A of lateral hypothalamic area(LHA) effects on the gastric motility in rats. We selected Wistar rats as our subjects. A stainless-steel injection cannula was implanted unilaterally into the LHA. A force transducer was embedmented into the stomach to record circular muscle contractiontions in freely moving conscious rats. The gastric motility was monitored by administration of ghrelin into LHA. The changes of amplitude of constriction and frequency of gastric motility were monitored in conscious rats by a transducer. Subdiaphragmatic vagotomy was performed to elucidate the neural pathways of orexin-A. After microinjection of orexin-A into LHA 5-20 min later, Orexin-A dose-dependently increased the amplitude of contraction and accelerated frequency of gastric motility in the stomach. The effect of orexin-A on promoting the amplitude and frequency of gastric contraction disappeared after 0.5μg orexin-A +6.0μg SB-334867 mixture was microinjection into LHA. However, there was no significant changes of amplitude and frequency of gastric contraction while injection of orexin-A receptor antagonists SB-334867 alone. The stimulatory effect of orexin-A on gastric motility was abolished by subdiaphragmatic vagotomy. It is suggested that exogenous orexin-A of LHA may promote gastric motility, the effect may be accomplished through the LHA-vagus pathway.

The secretion of LH during the preovulatory surge has been shown to be pulsatile in several species. We confirmed this phenomenon in intact ewes in two experiments in which we studied the LH surge in detail. In the first experiment, the levels of LH were measured in discrete blood samples taken every 5 min around the onset of oestrus in 5 intact Merino ewes. For 2-5 h immediately prior to the onset of the surge, the median pulse interval was 17.5 min (range 10-55) and the median pulse amplitude was 0.70 ng/ml (range 0.28-1.33 ng/ml). During the ascending phase of the surge, the pulse interval did not change significantly (median 18.3 min) but the median pulse amplitude increased 20 fold to 18.0 ng/ml. During the descending phase, the median pulse interval was 22.5 min and the median amplitude decreased to 8.1 ng/ml (P less than 0.005). During the surge, intervals of 10 min and amplitudes over 30 ng/ml were common. In the second experiment with 2 oestrous Romanov x Préalpes-du-Sud ewes, blood was withdrawn continuously and samples were pooled over 4 min periods for 19-27 h. In the resulting profiles, individual pulses were better defined but the pulse frequencies (median interval 15.2 min during ascending phase) and amplitudes (median 35.0 ng/ml) varied in similar fashion to the Merinos. Using a simple mathematical description of pulsatile secretion, and assuming that LH is only released in pulses, we also found that the high concentrations normally achieved during the surge can only be explained by pulse frequencies and amplitudes well above those normally observed in other physiological situations, including the follicular phase or following ovariectomy. These findings strongly support the experimental data and the combined results of the two studies suggest that the initiation and execution of the LH surge is probably accomplished by changes in the amplitude of pulses. A high frequency is also essential and our data suggest that it may be established some time before the onset of the surge proper, but this requires confirmation. Respectively, the changes in amplitude and frequency reflect the pituitary and hypothalamic components of the positive feedback mechanism. The theoretical study suggested that a change in clearance rate could also contribute to the surge and this awaits further investigation.

1. The responses of neurons located in the rostral part of the fastigial nucleus to sinusoidal tilt of the animal were recorded in precollicular decerebrate cats and compared with those elicited by the same stimulation in Purkinje (P) cells located in the vermal cortex of the cerebellar anterior lobe. In particular, by fixing the head and the body of the animal to the tilting table and by rotating the animal around its longitudinal axis, it was possible to elicit a selective labyrinth input without eliciting a neck input. 2. Among the 60 fastigial neurons tested, 43 units responded to sinusoidal tilt at the frequency of 0.026 Hz and at the peak amplitude of displacement of 10°–15°. On the other hand, among 106 P-cells tested for a mossy fiber (MF) response to the labyrinth input, 32 units were affected by the same parameters of stimulation. In both instances the response consisted in a periodic modulation of the discharge frequency, which was related to the position of the animal. Most of the responses of the fastigial units to the labyrinth input were characterized by a peak excitation in phase with side-down tilt of the animal and by inhibition during side-up tilt, whereas most of the MF-responses of the P-cells to the labyrinth input showed just the opposite behavior. 3. The threshold amplitude of tilt responsible for these responses varied in different units from 1° to 3° at the frequency of 0.026 Hz. The sensitivity of the first harmonic of the unit responses to tilt, expressed in percentage change of the average firing rate per degree of displacement, corresponded on the average to 1.73±1.16, S.D., for the fastigal neurons and to 1.61±0.94, S.D., for the P-cells. These values did not change or were only slightly modified as a result of increasing amplitude of stimulation from 1°–3° to 15°–25° at a frequency of 0.026 Hz. Moreover, changes in amplitude of stimulation at the parameters reported above did not greatly modify the phase angle of the first harmonic of the responses relative to the side-down position of the animal. Units located in the medial corticonuclear zone of the cerebellum did not show any change in sensitivity and phase angle of the responses by increasing the frequency of tilt from 0.015 to 0.20 Hz at the fixed amplitude of 10°–15°, thus indicating that these responses depended upon stimulation of macular receptors. In other units, however, these changes in frequency of rotation modified the phase angle of the responses, which became related to velocity rather than to the positional signal, due to stimulation of semicircular canal receptors. 4. The observation that most of the responsive fastigial neurons increased their firing rate, while most of the responding P-cells located in the vermal cortex of the cerebellar anterior lobe decreased their firing rate during side-down rotation of the animal is discussed in relation to the postural changes of the limbs elicited during asymmetric stimulation of macular receptors.

Effects of partial occlusion of circulation on frequency and amplitude of surface electromyography

Local Presynaptic Activity Gates Homeostatic Changes in Presynaptic Function Driven by Dendritic BDNF Synthesis

An adaptive gain control system of a proprioceptive feedback system, the femur­tibia control loop, is investigated. It enables the joint control loop to work with a high gain but it prevents instability oscillations. In the inactive stick insect, the realisation of specific changes in gain is described for tibial torque, for extensor tibiae muscle force and for motoneuronal activity. In open-loop experiments, sinusoidal stimuli are applied to the femoral chordotonal organ (fCO). Changes in gain that depend on fCO stimulus parameters (such as amplitude, frequency and repetition rate), are investigated. Furthermore, spontaneous and touch-induced changes in gain that resemble the behavioural state of the animal are described. Changes in gain in motoneurones are always realised as changes in the amplitude of modulation of their discharge frequency. Nevertheless, depending on the stimulus situation, two different mechanisms underlie gain changes in motoneurones. (i) Changes in gain can be based on changes in the strength of the sensorimotor pathways that transmit stimulus-modulated information from the fCO to the motoneurones. (ii) Changes in gain can be based on changes in the mean activity of a motoneurone by means of its spike threshold: when, during the modulation, the discharge of a motoneurone is inhibited for part of the stimulus cycle, then a change in mean activity subsequently causes a change in modulation amplitude and gain. A new neuronal mechanism is described that helps to compensate the low-pass filter characteristics of the muscles by an increased activation, especially by a sharper distribution of spikes in the stimulus cycle at high fCO stimulus frequencies.

EMG activity of low back extensor muscles during cyclic flexion/extension

: A passive environmental sensor was evaluated as an input device capable of presenting tactile data to a human. The experiment provided information on the ability of the human to detect differences within the range of the vibratory transducer. Frequency discrimination thresholds showed wide differences between subjects and a significant increase in human sensitivity at one point of the frequency input levels. This increases sensitivity was explained in terms of the resonant frequency of the vibratory and also in terms of the generally known high human sensitivity for amplitude and frequency changes at 200-300 cps. It was concluded that for fine-grain data discrimination individual differences may influence the final design of the sensor. However, these differences may be reduced and the sensitivity of the user improved if its electronic design and its transducers provide redundancy to the human.