High visual perceptual load reduces prepulse inhibition induced by task-unrelated and task-related sound.

Prepulse inhibition (PPI) is an automatic and pre-attentive sensorimotor gating process. Several studies have shown that advanced cognitive functions can modulate PPI. This study aimed to further elucidate the modulatory effect of attentional resource allocation on PPI. We examined the differences in PPI between high and low attentional loads. First, we verified that the adapted feature versus combination visual search paradigm could produce high and low perceptual load differences according to the task demands. Second, we measured the participants' task-unrelated PPI during the visual search task and found that the PPI in the high-load condition was significantly lower than that in the low-load condition. To further elucidate the role of attentional resources, we tested task-related PPI using a dual-task paradigm in which participants were instructed to complete a visual task with an auditory discrimination task. We found a result similar to that of the task-unrelated experiment. The participants in the high-load condition had less PPI than those in the low-load condition. Finally, we ruled out the possibility that the working memory load explains the modulation of PPI. In line with the theory of PPI modulation, these results suggest that allocating limited attentional resources to the prepulse modulates PPI. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Negative emotion-conditioned prepulse induces the attentional enhancement of prepulse inhibition in humans.

Prepulse inhibition (PPI) is a reduction of the acoustic startle reflex (ASR) when the startling stimulus is preceded by a weaker and non-startling stimulus (i.e., prepulse). Previous studies have revealed that PPI can be top-down modulated by selective attention to the fear-conditioned prepulse in animals. However, few researchers have tested this assumption in humans. Thus, in this study, the negative emotional-conditioned prepulse (CS+) was used to explore whether it could improve participants' attention, and further improve the PPI. The results showed that the CS+ prepulse increased the PPI only in females, PPI produced by CS+ prepulse was larger in females than in males, and the perceptual spatial attention further improved the PPI in both females and males. The results suggested that the PPI was affected by emotional, perceptual spatial attention, and sex. These findings highlight an additional method to measure top-down attentional regulation of PPI in humans. Which may offer a useful route to enhance the diagnosis of affective disorders, such as anxiety, depression, and post-traumatic stress disorder.

Different binaural processing of the envelope component and the temporal fine structure component of a narrowband noise in rat inferior colliculus.

Complex broadband sounds are decomposed by peripheral auditory filters into a series of relatively narrowband signals, each with a slowly varying envelope (ENV) and a rapidly fluctuating temporal fine structure (TFS). ENV and TFS information at the bilateral ears contribute differentially to auditory perception. However, whether the difference could attribute to mechanisms of binaural integration remains an open question. As a potential neural correlate, subsets of neurons in the central nucleus of the inferior colliculus (ICC) are known to integrate binaural information with binaural inhibition or binaural summation. Therefore, we recorded the frequency-following responses (FFRs) to the ENV and TFS components of narrowband noises in the ICC of anesthetized rats and examined changes in FFR amplitude and stimulus-response coherence under various sound-delivery settings. We showed that binaural FFRENV was predominantly elicited by contralateral inputs and inhibited by ipsilateral inputs, exhibiting a "binaural-inhibition" like property. On the other hand, binaural FFRTFS received a balanced contribution from both sides, echoing the "binaural-summation" mechanism. What is more, binaural FFRENV was significantly correlated with contralateral-evoked but not ipsilateral-evoked FFRENV, while binaural FFRTFS correlated with both contralateral- and ipsilateral-evoked FFRTFS. Overall, these results suggest distinct binaural processing of ENV and TFS information at the midbrain level.

Impaired interaural correlation processing in people with schizophrenia.

Detection of transient changes in interaural correlation is based on the temporal precision of the central representations of acoustic signals. Whether schizophrenia impairs the temporal precision in the interaural correlation process is not clear. In both participants with schizophrenia and matched healthy-control participants, this study examined the detection of a break in interaural correlation (BIC, a change in interaural correlation from 1 to 0 and back to 1), including the longest interaural delay at which a BIC was just audible, representing the temporal extent of the primitive auditory memory (PAM). Moreover, BIC-induced electroencephalograms (EEGs) and the relationships between the early binaural psychoacoustic processing and higher cognitive functions, which were assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), were examined. The results showed that compared to healthy controls, participants with schizophrenia exhibited poorer BIC detection, PAM and RBANS score. Both the BIC-detection accuracy and the PAM extent were correlated with the RBANS score. Moreover, participants with schizophrenia showed weaker BIC-induced N1-P2 amplitude which was correlated with both theta-band power and inter-trial phase coherence. These results suggested that schizophrenia impairs the temporal precision of the central representations of acoustic signals, affecting both interaural correlation processing and higher-order cognitions.

Attribute capture underlying the precedence effect in rats.

In a reverberant environment, humans with normal hearing can perceptually fuse the soundwave from a source with its reflections off nearby surfaces into a single auditory image, whose location appears to be around the source. This phenomenon is called the precedence effect, which is based on the perceptual capture of the reflected (lagging) sounds' attributes by the direct wave from the source. Using the paradigm of attentional modulation of the prepulse inhibition (PPI) of the startle reflex, with both the prepulse-feature specificity and the perceived-prepulse-location specificity, this study was to examine whether the perceptual attribute capture underlying the precedence effect occurs in rats. One broadband continuous noise was delivered by each of two spatially separated left and right loudspeakers with a 1-ms inter-loudspeaker delay. A silent gap was embedded in one of the two noises as the prepulse stimulus. The results showed that regardless of whether the gap was physically in the leading or lagging noise when the leading noise was either the left or right one, fear conditioning the gap enhanced PPI only when the leading noise was delivered from the loudspeaker that was the leading but not the lagging loudspeaker during the conditioning, indicating that due to the spatial specificity (either left or right) in the attentional enhancement of PPI, the perceived location of the conditioned gap was always on the leading side even though the gap was physically on the lagging side. Thus, rats have the same perceptual ability of attribute capture, thereby experiencing the auditory precedence effect as humans.

Spatial specificity in attentional modulation of prepulse inhibition of the startle reflex in rats.

Prepulse inhibition (PPI), the suppression of the startle reflex when the startling stimulus is shortly preceded by a weaker non-startling sensory stimulus (prepulse), can be enhanced by selective attention to the prepulse with a marked prepulse-feature specificity. To determine if the attentional modulation of PPI in rats can also be perceptual location specific, this study investigated whether fear-conditioning of a prepulse perceived at a location can enhance PPI only when the conditioned prepulse is perceived at that conditioned location. A continuous narrowband noise (NBN) was delivered by each of the two spatially separated loudspeakers in the frontal azimuth with a silent gap embedded in each NBN. The inter-loudspeaker interval was 1 ms (either left or right loudspeaker leading). Due to the precedence effect, both the NBN and gap images were perceived at the leading loudspeaker. The perceptually fused gap was used as the prepulse. To fear-condition one gap prepulse, which was perceived at one loudspeaker, the prepulse was paired with footshock in a temporally precise manner and the other gap (the conditioning-control prepulse) perceived at the other (opposite) loudspeaker was paired with footshock in a random manner. Compared to PPI before conditioning, PPI induced by the fear-conditioned gap perceived at the fear-conditioned loudspeaker, but not that by the conditioning-control gap, was significantly enhanced. Thus, attentional modulation of PPI can be not only prepulse-feature specific, but also perceptual location specific, and involves combined central processes for content and location information.

The medial agranular cortex mediates attentional enhancement of prepulse inhibition of the startle reflex.

The startle reflex, which interferes with on-going cognitive/behavioral activities, is of important protective function for humans and animals. Prepulse inhibition (PPI), as an operational measure of sensorimotor gating, is the suppression of the startle reflex in response to an intense startling stimulus (pulse) when this startling stimulus is shortly preceded by a weaker non-startling stimulus (prepulse). In both humans and laboratory animals, PPI can be enhanced by facilitating selective attention to the prepulse, suggesting that higher-order cognitive/perceptual processes modulate PPI. It has been well known that both the cholinergic system located in the basal forebrain and the deep layers of the superior colliculus in the PPI-mediating circuit are top-down modulated by the medial agranular cortex (AGm), which is a subdivision of the medial prefrontal cortex (PFC) and has wide axonal connections with both cortical regions (including the posterior parietal cortex) and subcortical structures critical for attention/orientation processes. This study investigated whether the AGm is involved in attentional modulation of PPI. The results showed that PPI was enhanced by fear conditioning of the prepulse, and then further enhanced by perceived spatial separation between the conditioned prepulse and a back-ground masking noise based on the auditory precedence effect. Bilateral injection of 2-mM kynurenic acid, a broad spectrum antagonist of glutamate receptors, into the AGm, but not the primary somatosensory cortex, eliminated these two types of attentional enhancement of PPI. Thus, the AGm plays a role in facilitating attention to the prepulse and is involved in the top-down modulation of PPI.

Single frequency thermal wave radar: A next-generation dynamic thermography for quantitative non-destructive imaging over wide modulation frequency ranges.

Single-Frequency Thermal Wave Radar Imaging (SF-TWRI) was introduced and used to obtain quantitative thickness images of coatings on an aluminum block and on polyetherketone, and to image blind subsurface holes in a steel block. In SF-TWR, the starting and ending frequencies of a linear frequency modulation sweep are chosen to coincide. Using the highest available camera frame rate, SF-TWRI leads to a higher number of sampled points along the modulation waveform than conventional lock-in thermography imaging because it is not limited by conventional undersampling at high frequencies due to camera frame-rate limitations. This property leads to large reduction in measurement time, better quality of images, and higher signal-noise-ratio across wide frequency ranges. For quantitative thin-coating imaging applications, a two-layer photothermal model with lumped parameters was used to reconstruct the layer thickness from multi-frequency SF-TWR images. SF-TWRI represents a next-generation thermography method with superior features for imaging important classes of thin layers, materials, and components that require high-frequency thermal-wave probing well above today's available infrared camera technology frame rates.

Electro- and photodriven phase change composites based on wax-infiltrated carbon nanotube sponges.

Organic phase change materials are usually insulating in nature, and they are unlikely to directly trigger latent heat storage through an electrical way. Here we report a multifunctional phase change composite in which the energy storage can be driven by small voltages (e.g., 1.5 V) or light illumination with high electro-to-heat or photo-to-thermal storage efficiencies (40% to 60%). The composite is composed of paraffin wax infiltrated into a porous, deformable carbon nanotube sponge; the latter not only acts as a flexible encapsulation scaffold for wax but also maintains a highly conductive network during the phase change process (for both solid and liquid states). Uniform interpenetration between the nanotube network and paraffin wax with high affinity results in enhanced phase change enthalpy and thermal conductivity compared to pure paraffin wax. Our phase change composite can store energy in practical ways such as by sunlight absorption or under voltages applied by conventional lithium-ion batteries.