The value of dual-energy computed tomography angiography-based virtual monoenergetic imaging for evaluations after cerebral aneurysm clipping.

Purpose: This study aimed to research the optimal energy range of dual-energy computed tomography angiography (DECTA)-based virtual monoenergetic imaging (VMI) for evaluations after cerebral aneurysm clipping.

Methods: Sixty patients who underwent DECTA after cerebral aneurysm clipping were analyzed retrospectively. Conventional computed tomography angiography (CTA) was compared with VMIs at 60, 70, 80, 90, and 100 keV.

[Sound duration and sound pattern affect the recovery cycles of inferior collicular neurons in leaf-nosed bat, Hipposideros armiger].

The effects of sound duration and sound pattern on the recovery cycles of inferior collicular (IC) neurons in constant frequency-frequency modulation (CF-FM) bats were explored in this study. Five leaf-nosed bats, Hipposideros armiger (4 males, 1 female, 43-50 g body weight), were used as subjects. The extracellular responses of IC neurons to paired sound stimuli with different duration and patterns were recorded, and the recovery was counted as the ratio of the second response to the first response.

[Perception and selectivity of sound duration in the central auditory midbrain].

Sound duration plays important role in acoustic communication. Information of acoustic signal is mainly encoded in the amplitude and frequency spectrum of different durations. Duration selective neurons exist in the central auditory system including inferior colliculus (IC) of frog, bat, mouse and chinchilla, etc.

Effects of modulation range and presentation rate of FM stimulus on auditory response properties of mouse inferior collicular neurons.

In natural acoustical environments, most biologically related sounds containing frequency-modulated (FM) components repeat over periods of time. They are often in rapid sequence rather than in temporal isolation. Few studies examined the neuronal response patterns evoked by FM stimuli at different presentation rates (PR).

[Selectivity for the rate of frequency-modulated sweeps and its affecting factors in the inferior collicular neurons of mouse].

Both animal communication sounds and human speech contain frequency-modulated (FM) sweeps. Although the selectivity for the rate of FM sweeps in neurons has been found in many kinds of animals at different levels of the central auditory structures, the underlying neural mechanism is still not clear. Using extracellular single unit recording techniques, we examined the selectivity for the rate of FM sweeps in the inferior colliculus (IC) neurons of the Kunming mouse (Mus musculus, Km) in the free-field stimulation conditions and determined its affecting factors.

Involvement of GABA-mediated inhibition in shaping the frequency selectivity of neurons in the inferior colliculus of the big brown bat, Eptesicus fuscus.

In central auditory signal processing, neural inhibition plays an important role in sharpening the selectivity of auditory neurons. The present study examines the involvement of GABA-mediated inhibition in shaping the frequency selectivity of neurons in the bat inferior colliculus (IC) using forward masking paradigm and bicuculline application. At each study session, we recorded two IC neurons with a pair of electrodes and reciprocally studied whether a sound that served as a probe to elicit response of one neuron might serve as a masker to affect the frequency tuning curve (FTC) of the other paired neuron.

GABA-mediated modulation of the discharge pattern and rate-level function of two simultaneously recorded neurons in the inferior colliculus of the big brown bat, Eptesicus fuscus.

Neurons in the central nucleus of the inferior colliculus (IC) receive excitatory and inhibitory inputs from both lower and higher auditory nuclei. Interaction of these two opposing inputs shapes response properties of IC neurons. In this study, we examine the interaction of excitation and inhibition on the responses of two simultaneously recorded IC neurons using a probe and a masker under forward masking paradigm.

The recovery cycle of bat duration-selective collicular neurons varies with hunting phase.

During hunting, duration selectivity and recovery cycle underlie a bat's ability to determine echo duration and target distance (echo ranging). This study shows that the recovery cycle of most duration-selective neurons in the bat central nucleus of the inferior colliculus neurons varies with biologically relevant pulse-echo (P-E) duration and amplitude. As such, neurons with short best duration recover rapidly when stimulated with P-E pairs with short duration and small P-E amplitude difference, whereas neurons with long best duration recover rapidly when stimulated with P-E pairs with long duration and large P-E amplitude difference.

GABAergic inhibition modulates intensity sensitivity of temporally patterned pulse trains in the inferior collicular neurons in big brown bats.

The echolocating big brown bats (Eptesicus fuscus) emit trains of frequency-modulated (FM) biosonar signals with duration, amplitude, repetition rate, and sweep structure changing systematically during interception of their prey. In the present study, the sound stimuli of temporally patterned pulse trains at three different pulse repetition rates (PRRs) were used to mimic the sounds received during search, approach, and terminal stages of echolocation. Electrophysiological method was adopted in recordings from the inferior colliculus (IC) of midbrain.

Duration-sensitive neurons in the inferior colliculus of horseshoe bats: adaptations for using CF-FM echolocation pulses.

The present study examines duration-sensitive neurons in the inferior colliculus (IC) of the least horseshoe bat, Rhinolophus pusillus, from China. In contrast to other bat species tested for duration selectivity so far, echolocation pulses emitted by horseshoe bats are generally longer and composed of a long constant-frequency (CF) component followed by a short downward frequency-modulated (FM) sweep (CF-FM pulse). We used combined CF-FM pulses to analyze the differential effects that these two pulse components had on the duration tuning in neurons of the horseshoe bat's IC.

The amplitude sensitivity of mouse inferior collicular neurons in the presence of weak noise.

Natural auditory environment consists of multiple sound sources that are embedded in ambient strong and weak noise. For effective sound communication and signal analysis, animals must somehow extract biologically relevant signals from the inevitable interference of ambient noise. The present study examined how a weak noise may affect the amplitude sensitivity of neurons in the mouse central nucleus of the inferior colliculus (IC) which receives convergent excitatory and inhibitory inputs from both lower and higher auditory centers.

Preceding weak noise sharpens the frequency tuning and elevates the response threshold of the mouse inferior collicular neurons through GABAergic inhibition.

In acoustic communication, animals must extract biologically relevant signals that are embedded in noisy environment. The present study examines how weak noise may affect the auditory sensitivity of neurons in the central nucleus of the mouse inferior colliculus (IC) which receives convergent excitatory and inhibitory inputs from both lower and higher auditory centers. Specifically, we studied the frequency sensitivity and minimum threshold of IC neurons using a pure tone probe and a weak white noise masker under forward masking paradigm.

Different forward masking patterns of sustained noise burst and segmental noise burst in the inferior collicular neurons of the mouse.

Although there has been a growing body of literature showing the neural correlation of forward masking caused by a pure tone masker in the auditory neurons, relative few studies have addressed the description of how the forward masking caused by a noise burst, especially a sequence of noise burst, is transformed into neuronal representation in the central auditory system. Using a noise forward masking paradigm under free field stimuli conditions, this in vivo study was devoted to exploring it in the inferior collicular (IC) neurons of the mouse (Mus musculus KM). A total of 96 IC neurons were recorded.

Effects of backward masking on the responses of the inferior collicular neurons in the big brown bat, Eptesicus fuscus.

Temporal features of sound convey information vital for behaviors as diverse as speech recognition by human and echolocation by bats. However, auditory stimuli presented in temporal proximity might interfere with each other. Although much progress has been made in the description of this phenomenon from psychophysical studies, the neural mechanism responsible for its formation at central auditory structures especially at the inferior colliculus (IC), a midbrain auditory nucleus which practically receives massive bilateral projections from all the major auditory structures in the brainstem, remains unclear.

Dynamic modulations on intensity sensitivity evoked by weak noise in the inferior collicular neurons.

In order to explore the possible mechanisms by which ethologically relevant sounds can be extracted from complex auditory environments, this study examined the effects of weak noise on the rate-intensity functions (RIFs) of neurons responding to tone burst in the inferior colliculus (IC) of nine mice (Mus musculus Km). Under free field stimuli conditions, a total of 112 IC neurons were recorded. RIFs with and without simultaneous presentation of weak noise, of which the intensity was relative to 5 dB below minimum threshold of tone burst, were measured in 44 IC neurons.