Auditory guidance systems for the visually impaired people / 生物医学工程学杂志

Visually impaired people face many inconveniences because of the loss of vision. Therefore, scientists are trying to design various guidance systems for improving the lives of the blind. Based on sensory substitution, auditory guidance has become an interesting topic in the field of biomedical engineering. In this paper, we made a state-of-technique review of the auditory guidance system. Although there have been many technical challenges, the auditory guidance system would be a useful alternative for the visually impaired people.

Spatio-temporal distribution of chromatic VEPs / 生物医学工程学杂志

The VEPs evoked by different colors are differently distributed on human cerebral cortex. This study sought to shed light on the spatio-temporal distribution of chromatic VEPs and compare the distribution characteristics of chromatic VEPs evoked by different colors in different cerebral cortex regions. The subjects were asked to stare at the red, green, black gradient bars against a white background. The results show that the latency periods and the amplitudes of P1 and N1 peaks from different chromatic VEPs exhibit significant differences (P<0.001). The speed and intensity of cognitive task of red are higher than those of green. The latency periods and the amplitudes of P1 and N1 peaks from different cerebral cortex regions also display remarkable differences (P<0.001). The intensity of reaction in the temporal and occipital regions is stronger than that in other regions, and the latency periods in frontal area and central area are shorter than those in temporal and occipital regions.

Entropy analysis of the EEG alpha activity in depression patients / 生物医学工程学杂志

The alpha rhythm in electroencephalograph has been associated with the mental state of the brain. The aim of the present study was to analyze the complexity of the alpha activity in depression patients by Renyi entropy (RE) under two conditions, i.e., resting with eyes closed followed by a simple mental arithmetic. The EEGs were recorded in 20 depression patients and 20 age-matched control subjects. Results showed that the alpha activity of depression patients is more complex during resting and is more regular during the mental arithmetic than that of the controls. RE analysis can well characterize the alpha activity in depression patients and could be a valuable tool to study cognitive process and also a potential effective approach for the diagnosis of depression.

Gender difference in face recognition / 生物医学工程学杂志

The method of event-related potentials (ERP) was used to study the gender difference in face recognition. The stimuli in the experiment were 10 upright and 10 inverted face photos. The subjects, half female and half male, were asked to judge whether the face was upright or inverted. The results showed that the N170 wave forms were observed in the occipito-temporal regions and they were found exhibiting brain's right hemispheric dominance. The stimuli of different gender photos were noticed to have no significant impact on the N170 wave forms, but there were significant differentce in the amplitude and latency period of N170 between different gender participants. Moreover, there was marked difference in the latency period of the male participants watching the same gender face and different gender face. Similar results were not found in the ERP's latency period of female participants.

Recurrence plot analysis of HRV for brain ischemia and asphyxia / 生物医学工程学杂志

Heart rate variability (HRV) is the tiny variability existing in the cycles of the heart beats, which reflects the corresponding balance between sympathetic and vagus nerves. Since the nonlinear characteristic of HRV is confirmed, the Recurrence Plot method, a nonlinear dynamic analysis method based on the complexity, could be used to analyze HRV. The results showed the recurrence plot structures and some quantitative indices (L-Mean, L-Entr) during asphyxia insult vary significantly as compared to those in normal conditions, which offer a new method to monitor brain asphyxia injury.

Review of visual prosthesis (I)--retinal prosthesis / 生物医学工程学杂志

Research on how to totally or partially restore the vision has attracted more attention in the fields of neural engineering and tissue engineering. Neural interface and visual prosthesis offer alternative ways for partially repairing the visual impairment. The most widely used visual prosthetics are based on retinal stimulation. This article is a state-of-art review of the principles, technical details and the limitations of retinal prosthesis.

Review of visual prosthesis (II)--cortical visual prosthesis, optic nerve prosthesis and vision substitution devices / 生物医学工程学杂志

Cortical visual prosthesis, optic nerve visual prosthesis and vision substitution devices are alternative ways for repairing the visual impairment in case of optic nerve injury, retina lose or blindness without fully developed central visual system. This article is a state-of-art review of the principles, technical details and the limitations of different types of prostheses beyond the retinal prosthesis.

Review of researches on retinal model / 生物医学工程学杂志

Retinal model is an essential part in the retinal prosthesis. Based on the retinal physiology and the experimental data, the model is able to simulate the information processing in the retina, and can be used to investigate the relation between the input image and the neuron firing. We can categorize the models into circuit realization and algorithm realization. This article is a state-of-art review of different types of retinal models.

Removal of artifacts from EEG signal / 生物医学工程学杂志

As a kind of physiological signals, the electroencephalogram (EEG) represents the electrical activity of the brain. Because of its higher time-varying sensitivity, EEG is susceptible to many artifacts, such as eye-movements, blinks, cardiac signals, muscle noise. These noises in recording EEG pose a major embarrassment for EEG interpretation and disposal. A number of methods have been proposed to overcome this problem, ranging from the rejection of various artifacts to the effect estimate of removing artifacts. This paper reviews many kinds of methods for artifact rejection in the EEC recently, including regression-based methods, artifact subtraction, principal component analysis (PCA), independent component analysis (ICA) and wavelet transform. The specific assumptions of each method and its advantage/disadvantage are also summarized.

Nonlinear dynamics characteristics in alpha rhythm of scalp electroencephalogram / 生物医学工程学杂志

In regard to the controls and schizophrenia EEGs, we have got alpha rhythm from three points of view and verified the nonlinearity of the three kinds of rhythms. The results show that neither normal EEG alpha nor patients EEG alpha have the typical nonlinear characteristics. Therefore, we could not blindly use the theories of nonlinear dynamics to analyze the rhythm of brain wave.

Analysis of HRV from brain injury by use of nonextensive relative entropy / 生物医学工程学杂志

Due to its great clinical significance, brain injury following cardiac arrest (CA) has attracted more attention now. Meanwhile, there are currently no approved real time objective methods used to monitor brain injury following CA. In this study, we adopt the method of nonextensive Kullback-Leibler Entropy in investigating the HRV signals from brain injury and compare the result with that of corresponding EEG analysis. The comparative analysis shows that Kullback-Leibler Entropy can reveal the injury level of brain following CA. And we propose a novel quantitative approach for monitoring brain injury.

Development of PET scanner for small animals / 医疗卫生装备

In comparison with the clinical PET scanner,PET scanner for small animals puts forward a higher demand in spacial resolution and sensitivity. This article describes the development of the PET scanner for small animals and compares the characteristics of several kinds of contemporary typical PET scanners for small animals in different aspects based on the development of detectors. Meanwhile,it also introduces the development of the detectors designed for measuring depth of interaction (DTC) to reduce parallax error.