Influences of attention on auditory aftereffects following purely visual adaptation

Recently, Kitagawa and Ichihara (2002) demonstrated that visual adaptation to an expanding or contracting disk produces a cross-modal visually-induced auditory loudness aftereffect (VALAE), which they attributed to cross-correlations of motion in three-dimensional space. Our experiments extend their results by providing evidence that attending selectively to one of two competing visual stimuli of the same saliency produces a cross-modal VALAE that favors the attended stimulus. These cross-modal attentional effects suggest the existence of integrative spatial mechanisms between vision and audition that are affected by attention.     

Evoked potentials of the auditory cortex on paired stimuli

Changes in the responsiveness of the auditory cortex to an acoustic click and to direct stimulation of the medial geniculate body were studied by the method of evoked potentials in an extended experiment on cats with implanted electrodes. It is shown that the minimum interval between two stimuli for which a second click produces an EP in the auditory cortex is from 30 to 50 msec. The relative refractory period consists of two parts. The first (50–100 msec) is characterized by a rapid recovery, and the second (about 500 msec) by a slow recovery. In contrast with a click, direct stimulation of the geniculate body does not produce a refractory condition but one of facilitation. The effects of Nembutal and chloralose anesthesia and the state of alertness on the recovery of auditory cortex responsiveness were investigated. The reason for the absence and the reduction of an EP from the auditory cortex to a testing click during absolute and relative refractory periods is not a passive decrease of excitability of the usual refractory kind, but an active interplay of excitatory and inhibitory processes in the cerebral cortex, geniculate bodies, and reticular formation of the brain stem.A. A. Bogomolets' Institute of Physiology, Academy of Sciences, Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 54–64, July–August, 1969.     

Effects of auditory stimuli on the lifespan of Drosophila melanogaster

It is well known that music can have calming effects on humans, other mammals and birds. Reducing environmental stress or enhancing the resistance to certain stressors has been shown to extend lifespan in several organisms. Evidence also suggests that mild temporary stress may also enhance stress resistance and ultimately slow the aging process. This study explored the possibility that music may influence the lifespan of the fruit fly Drosophila melanogaster, possibly by affecting responses to stress. Flies received either background sounds (control), or background sounds supplemented with music (experimental). The experimental group had classical music playing constantly at an average of 20 dB above background sound. The median lifespan of females receiving music was 42 days compared to the median of 45 days without music, but the difference was not significant. For males median lifespans were 42 days with music exposure, and 47 days without music and the difference was significant. These results suggest that exposure to classical music decreased the lifespan of male Drosophila. Both experimental and control populations showed age-dependent increases in mortality, indicating that music affects the normal aging process rather than showing overt toxicity. These results suggest that certain auditory stimuli may be stressful and can be used as insect management.     

Updating fearful memories with extinction training during reconsolidation: a human study using auditory aversive stimuli

Learning to fear danger in the environment is essential to survival, but dysregulation of the fear system is at the core of many anxiety disorders. As a consequence, a great interest has emerged in developing strategies for suppressing fear memories in maladaptive cases. Recent research has focused in the process of reconsolidation where memories become labile after being retrieved. In a behavioral manipulation, Schiller et al., (2010) reported that extinction training, administrated during memory reconsolidation, could erase fear responses. The implications of this study are crucial for the possible treatment of anxiety disorders without the administration of drugs. However, attempts to replicate this effect by other groups have been so far unsuccessful. We sought out to reproduce Schiller et al., (2010) findings in a different fear conditioning paradigm based on auditory aversive stimuli instead of electric shock. Following a within-subject design, participants were conditioned to two different sounds and skin conductance response (SCR) was recorded as a measure of fear. Our results demonstrated that only the conditioned stimulus that was reminded 10 minutes before extinction training did not reinstate a fear response after a reminder trial consisting of the presentation of the unconditioned stimuli. For the first time, we replicated Schiller et al., (2010) behavioral manipulation and extended it to an auditory fear conditioning paradigm.     

Auditory aftereffects of approaching and withdrawing sound sources: Dependence on the trajectory and location of adapting stimuli

Perception of approaching and withdrawing sound sources and their action on auditory aftereffects were studied in the free field. Motion of adapting stimuli was mimicked in two ways: (1) simultaneous opposite changes of amplitude of broadband noise impulses at two loudspeakers placed at 1.1 and 4.5 m from the listener; (2) an increase or a decrease of amplitude of broadband noise impulses in only one loudspeaker, the nearer or the remote one. Motion of test stimuli was mimicked in the former way. Listeners determined direction of the test stimuli motion without any adaptation (control) or after adaptation to stationary, slowly moving (with an amplitude change of 2 dB) and rapidly moving (amplitude change of 12 dB) stimuli. Percentages of “withdrawal” reports were used for construction of psychometric curves. Three phenomena of auditory perception were observed. In the absence of adaptation, a growing-louder effect was revealed, i.e., listeners reported more frequently the test sounds as the approaching ones. Once adapted to stationary or slowly moving stimuli, listeners showed a location-dependent aftereffect. Test stimuli were reported as withdrawing more often as compared with control. The effect was associated with the previous one and was weaker when the distance to the loudspeaker producing adapting stimuli was greater. After adaptation to rapidly moving stimuli, a motion aftereffect was revealed. In this case, listeners reported a direction of test stimuli motion as being opposite to that of adapting stimuli. The motion aftereffect was more pronounced when the adapting stimuli motion was mimicked in the former way, as this method allows estimation of their trajectory. There was no relationship between the motion aftereffect and the growing-louder effect, whichever way the adapting stimuli were produced. There was observed a tendency for reduction of aftereffects of approaching and for intensification of aftereffects of withdrawal with growing distance from source of adapting stimuli.     

Effects of acoustic stimuli on neuronal activity in the auditory cortex of the rat

Spontaneous activity of cortical neurons exhibits alternative fluctuations of membrane potential consisting of phased depolarization called "up-state" and persistent hyperpolarization called "down-state" during slow wave sleep and anesthesia. Here, we examined the effects of sound stimuli (noise bursts) on neuronal activity by intracellular recording in vivo from the rat auditory cortex (AC). Noise bursts increased the average time in the up-state by 0.81+/-0.65 s (range, 0.27-1.74 s) related to a 10 s recording duration. The rise times of the spontaneous up-events averaged 69.41+/-18.04 ms (range, 40.10-119.21 ms), while those of the sound-evoked up-events were significantly shorter (p<0.001) averaging only 22.54+/-8.81 ms (range, 9.31-45.74 ms). Sound stimulation did not influence ongoing spontaneous up-events. Our data suggest that a sound stimulus does not interfere with ongoing spontaneous neuronal activity in auditory cortex but can evoke new depolarizations in addition to the spontaneous ones.     

Modulation of perception and neurophysiological correlates of brief CO2 laser stimuli in humans using concurrent large fiber stimulation

It has been postulated that peripheral large fiber stimulation could modulate pain perception, probably by gating the input from AS-and C-fibers. The present study examined the effects of concurrent large fiber stimulation on the perception and neurophysiological correlates of brief CO2 laser stimuli known to activate A- and C-nociceptor endings selectively. Four test stimuli of brief non-painful and painful CO2 laser pulses (duration 50 ms; diameter 5 mm; intensity range 0.116-0.212J) were delivered at random every 5-10s on the dorsum of the left forearm of ten healthy subjects. Large fiber stimulation was performed by a dynamic soft brush applied either adjacently to test stimuli (segmental brush condition) or on the dorsum of the contra-lateral foot (extrasegmental brush condition). Perception, reaction time (RT) and laser-evoked potentials (EPs) were examined for conditions with brush and without brush (control condition). The signal detection theory (SDT) was used to evaluate the discrimination performance and the decision criterion. During extrasegmental brushing, these variables were unaffected as compared with control conditions. During segmental brushing, the absolute detection threshold increased, the probability of detection decreased and the RT increased. Interestingly, the stimulus-response curve of detected stimuli and late LTPs did not change significantly. SDT analysis showed that segmental brushing did not change the discrimination performance or sensitivity but increased significantly the subject's decision criterion for reporting sensation. It was concluded that segmental brushing acted primarily at supra-spinal levels and not by gating the input from small primary afferents activated selectively by brief CO2 laser stimuli.     

Behavioral determination of stimulus pair discrimination of auditory acoustic and electrical stimuli using a classical conditioning and heart-rate approach

Acute animal preparations have been used in research prospectively investigating electrode designs and stimulation techniques for integration into neural auditory prostheses, such as auditory brainstem implants and auditory midbrain implants. While acute experiments can give initial insight to the effectiveness of the implant, testing the chronically implanted and awake animals provides the advantage of examining the psychophysical properties of the sensations induced using implanted devices. Several techniques such as reward-based operant conditioning, conditioned avoidance, or classical fear conditioning have been used to provide behavioral confirmation of detection of a relevant stimulus attribute. Selection of a technique involves balancing aspects including time efficiency (often poor in reward-based approaches), the ability to test a plurality of stimulus attributes simultaneously (limited in conditioned avoidance), and measure reliability of repeated stimuli (a potential constraint when physiological measures are employed). Here, a classical fear conditioning behavioral method is presented which may be used to simultaneously test both detection of a stimulus, and discrimination between two stimuli. Heart-rate is used as a measure of fear response, which reduces or eliminates the requirement for time-consuming video coding for freeze behaviour or other such measures (although such measures could be included to provide convergent evidence). Animals were conditioned using these techniques in three 2-hour conditioning sessions, each providing 48 stimulus trials. Subsequent 48-trial testing sessions were then used to test for detection of each stimulus in presented pairs, and test discrimination between the member stimuli of each pair. This behavioral method is presented in the context of its utilisation in auditory prosthetic research. The implantation of electrocardiogram telemetry devices is shown. Subsequent implantation of brain electrodes into the Cochlear Nucleus, guided by the monitoring of neural responses to acoustic stimuli, and the fixation of the electrode into place for chronic use is likewise shown.     

Effect of contingent auditory stimuli on concurrent schedule performance: an alternative punisher to electric shock

This study explored whether load auditory stimuli could be used as functional punishing stimuli in place of electric shock. Three experiments examined the effect of a loud auditory stimulus on rats’ responding maintained by a concurrent reinforcement schedule. In Experiment 1, overall response rate decreased when a concurrent 1.5 s tone presentation schedule was superimposed on the concurrent variable interval (VI) 180-s, VI 180-s reinforcement schedule. On the contrary, response rate increased when a click presentation schedule was added. In Experiment 2, the extent of the response suppression with a 1.5 s tone presentation varied as a function of the frequency of the reinforcement schedule maintaining responses; the leaner the schedule employed, the greater the response suppression. In Experiment 3, response suppression was observed to be inversely related to the duration of the tone; response facilitation was observed when a 3.0-s tone was used. In Experiments 1 and 2, a preference shift towards the alternative with richer reinforcement was observed when the tone schedule was added. In contrast, the preference shifted towards the leaner alternative when the click or longer duration stimulus was used. These results imply that both the type and duration of a loud auditory stimulus, as well as the reinforcement schedule maintaining responses, have a critical role in determining the effect of the stimuli on responding. They also suggest that a loud auditory stimulus can be used as a positive punisher in a choice situation for rats, when the duration of the tone is brief, and the reinforcement schedule maintaining responses is lean.     

Convergence of visual and auditory stimuli on the neurons of the visual cortex in the conscious rabbit

We investigated the visual-cortex neurons of the conscious rabbit during simultaneous stimulation with a clicking sound and a light flash (complex) and during separate application of these stimuli. We tested the development of the reflex with time and of the sound-light association during prolonged rhythmic application of the sound and light. Fifty visual-cortex neurons were studied; 20% of the cells responded with a specific phased reaction and 16% exhibited a specific response to the complex different from the responses to each of its components. Development of a sound-light association was observed in 18% of the cells and a temporal reflex was induced in 25%. In most cases, the conditioned reaction evoked was similar to some informational element in the neuronal response to the complex.M. V. Lomonosov Moscow State University. Institute of Cybernetics, Academy of Sciences of the GruzSSR. Translated from Neirofiziologiya, Vol. 2, No. 4, pp. 391–398, July–August, 1970.     

The effects of supplementary olfactory and auditory stimuli on the stimulus value and mating success of the young boar

The aim of this study was to investigate the stimulus value and mating success of young boars in the presence or absence of exogenous boar-originating stimuli. Ten Large White × Landrace boars were exposed to each of the following treatments at 6 – 7 months of age (Period 1) and again at 9 – 10 months of age (Period 2): (1) no added boar stimuli; (2) added auditory stimuli; (3) added olfactory stimuli; (4) added auditory and olfactory stimuli. The efficacy of each treatment was determined by subjecting each boar to 2 × 5-min mating tests during each age-period, and assessing gilt proceptivity and sexual receptivity. Gilts used in these tests had been ovariectomized and were induced into behavioural oestrus using a threshold dose of oestradiol benzoate.The addition of both exogenous boar-originating stimuli (Treatment 4) significantly (P<0.05) increased gilt proceptivity and sexual receptivity in Period 1. This indicates that young post-pubertal boars may be deficient in both the auditory and olfactory stimulation that they provide to the female pig. No significant differences were observed between treatments during Period 2. These results therefore suggest that young boars (6–7 months of age) may have a lower stimulus value than their older counterparts, and that this may adversely affect mating success.     

Effect of sectioning the brachia of the inferior colliculi on the formation of auditory conditioned reflexes to amplitude-modulated stimuli

Elaboration of differentiation of tonal and amplitude-modulated stimuli with a frequency modulation of 5 Hz conducted on laboratory rats in five months after section of brachii colliculi proved to be impossible. The rate of correct reactions did not differ from the probability of random choice during 500 presentations of conditioned stimuli but significantly differed from the values obtained during differentiation of these signals in rats after control operation. Electrophysiological control showed that while in the control group and in intact animals at the presentation of amplitude-modulated stimuli with modulation frequency of 1-20 Hz summary potentials were recorded in the auditory cortex synchronized with their modulation frequency,--in rats after section of brachii colliculi only on- and off-responses were observed. It may be suggested that sensory providing of conditioned activity during the action of amplitude-modulated stimuli with low modulation frequency may be achieved only with the participation of specific pathways.     

Speech-intelligibility improvements using a binaural adaptive-scheme based conceptually on human auditory processing

A speech enhancement scheme is presented using diverse processing in sub-bands spaced according to a human-cochlear describing function. The binaural adaptive scheme decomposes the wide-band input signals into a number of band-limited signals, superficially similar to the treatment the human ears perform on incoming signals. The results of a series of intelligibility and formal listening tests are presented in which acoustic speech signals corrupted with recorded automobile noise were presented to 15 normal hearing volunteer subjects. For the experimental cases considered, the proposed binaural adaptive sub-band processing scheme delivers a statistically significant improvement in terms of both speech-intelligibility and perceived quality when compared with both the conventional wide-band processed and the noisy unprocessed case. The scheme is capable of extension to a potentially more flexible sub-band processing method based on a constrained artificial neural network (ANN).     

The effect of short-term sleep fragmentation produced by intense auditory stimuli on the arousal response to upper airway obstruction in lambs

Upper airway obstruction is recognized to cause apnoea in newborns as well as in adults. However, very little is known about factors that influence the arousal response from sleep during upper airway obstruction in newborns. Experiments were therefore done to investigate the effect of short-term sleep fragmentation on the arousal response to upper airway obstruction in six lambs aged 8 to 14 days. Each lamb was anaesthetized and instrumented for recordings of electrocorticogram, electro-oculogram, nuchal and diaphragm electromyograms and measurements of systemic arterial blood pressure and oxygen saturation (fiberoptic catheter oximeter). A tracheostomy was done and a fenestrated tracheostomy tube placed in the trachea. Experiments were not done before the third postoperative day. During a study, a 5F balloon tipped catheter was inserted into the tube so that airflow could be obstructed by inflating the balloon. Measurements were made during 30 s control periods and during experimental periods of upper airway obstruction in at least three epochs of quiet sleep and active sleep in each animal. These measurements were made following a period of uninterrupted sleep and repeated following a 36-42 h period of sleep fragmentation. Sleep fragmentation was produced by 30 s of noise separated by 2 min of quiet. Sleep fragmentation produced small but statistically significant increases in the time to arousal and decreases in the haemoglobin oxygen saturation at arousal during upper airway obstruction in quiet sleep but not active sleep. However, these changes, although consistent, were small and are of questionable biological significance. Therefore, I believe it is unlikely that short-term sleep fragmentation per se significantly impairs the arousal response to respiratory stimuli in newborns.     

Speech recognition by an artificial neural network using findings on the afferent auditory system

An artificial neural network which uses anatomical and physiological findings on the afferent pathway from the ear to the cortex is presented and the roles of the constituent functions in recognition of continuous speech are examined. The network deals with successive spectra of speech sounds by a cascade of several neural layers: lateral excitation layer (LEL), lateral inhibition layer (LIL), and a pile of feature detection layers (FDL's). These layers are shown to be effective for recognizing spoken words. Namely, first, LEL reduces the distortion of sound spectrum caused by the pitch of speech sounds. Next, LIL emphasizes the major energy peaks of sound spectrum, the formants. Last, FDL's detect syllables and words in successive formants, where two functions, time-delay and strong adaptation, play important roles: time-delay makes it possible to retain the pattern of formant changes for a period to detect spoken words successively; strong adaptation contributes to removing the time-warp of formant changes. Digital computer simulations show that the network detect isolated syllables, isolated words, and connected words in continuous speech, while reproducing the fundamental responses found in the auditory system such as ON, OFF, ON-OFF, and SUSTAINED patterns.