Neuroscience and Biomedical Engineering (Discontinued) - Current Issue

Brief cognitive screening tests performed by primary care physicians provide effective information for Alzheimer's patients and families regarding recent changes in daily living, behavior, intellectual functioning, and mood. In this review, we consider information in the literature concerning the practicality and accuracy of brief cognitive screening instruments currently utilized in primary care. Nine brief screening tests met our inclusion criteria and we discuss the characteristics, applicability, challenges, and development of each. We also review the relevance of the tactile sense, a novel element that improves the sensitivity of current screening methods. Finally, we discuss how new approaches involving tactile discrimination may offer the ability to discriminate patients with Alzheimer's disease from normal subjects.

Background: Osteonecrosis of the femoral head (ONFH) is a severe bone disease that may induce bone collapse. Early-stage ONFH (ARCO I-II) commonly involves conservative treatment. Evaluation of the treatment effects mainly relies on medical scans, which can provide morphologic information of the bone, but, there is lack of presentations of mechanical capabilities. Objective: The current study aims to propose mechanical parameters that can be used in evaluating the effectiveness of medical treatment on ONFH. Methods: Patient-specific models were established based on medical scans and anisotropic elastic properties of the bone are assigned based spatial-variant HU value. Finite element analysis was conducted in each model and the mechanical behavior of femur was compared between pre- and post-medical treatment. Results: Positive morphologic effects were found on all the studied patients after medical treatment; the necrosis-to-femoral head volume ratio was reduced. However, the stress distribution presents difference among cases. The stress index, defined as the ratio between the equivalent stress and compressive strength, is proposed and used to assess mechanical capability of the bone, the smaller value of which indicates better strength of the bone. In cases with necrosis at the superior region, the stress index reduces; while in the case with anteromedial-located necrosis, the stress index increases, indicating lesseffective treatment results and consistent to follow-up examinations. Conclusion: This study implicates that to evaluate the effectiveness of the medical treatment, morphologic change should be considered but mechanical capability of the bone, which is related to the size, elasticity and position of the necrosis, play a more important role.

Introduction: The wide-field visual cortex, known as MT+/V5 and V6 plays a major role in the visual processing of motion in the brain. In the current study, we located the MT+/V5 complex, which was divided into three sub-regions: the middle temporal (MT) area for central stimuli and the medial superior temporal (MST) area and V6 for peripheral stimuli. Previous studies of these areas were typically limited to the central (eccentricity is from 8° to 30°) visual fields. Methods: Using a wide-view presentation system, we presented a horizontal and vertical visual angle up to 120° in a functional magnetic resonance imaging (fMRI) environment. Result: Our results suggest that the MT+ area is significantly larger than indicated by previous studies on wide-field stimuli. The MST and V6 areas responded strongly to peripheral stimulation, and the MST responded strongly to ipsilateral stimulation, while MST also responded to central stimulation. Conclusion: Furthermore, we also used retinotopic mapping with stimuli consisting of motion dots to localize the MT+ and the wide-field motion area V6. The retinotopic maps divided the composition of the visual field maps into four segments within a functionally subdivided MT+.

Background: The integration of sound and visual information is an essential component of cognition. It has been proved that sound and visual stimuli features play key roles in the audiovisual integration.With regard to the color perception in visual stimuli, there are two cone pathways: a red-green and a blue-yellow at the level of the retina and the lateral geniculate nucleus. However, the effects of two color pathways on the audiovisual integration remain unclear. Objective: This study focused on studying the effects of the red-green and blue-yellow pathway on audiovisual integration. Methods: In this study, unimodal visual (three visual conditions: black-white, blue-yellow and redgreen), unimodal auditory, and bimodal audiovisual stimuli with three visual conditions were randomly presented at a 12-degree visual angle to the left or right of the center. The participants were asked for responding to the presented stimuli quickly and accurately. We used cumulative distribution functions to analyze the response times as a measure of audiovisual integration. In addition, the pairwise differences and t-tests were performed in cumulative distribution functions to compare the audiovisual integration with different visual conditions. Results: The statistical analysis results indicated that the facilitation of audiovisual integration in blackwhite condition was significant larger than red-green in the early stage and blue-yellow in the later stage. Additionally, the behavioral facilitation in red-green condition was significant larger than blueyellow condition in the later stage. Conclusion: These results suggested that the different color pathways affect both the behavioral facilitation and time of audiovisual integration.

Background: Past studies of neurophysiological differences between the dominant (dM1) and non-dominant (NdM1) motor hemispheres in response to motor training have had equivocal results, possibly due to a lack of training task novelty. Understanding differences between brain hemispheres in the capacity for neural plasticity in response to motor learning is important for rehabilitation and occupational settings. Objective: Our first objective was to develop an index finger tracking task that was equally challenging to both hands. The second objective was to measure neurophysiological changes in the dM1 and NdM1 in response to task performance. Methods: In the first experiment, 12 right-handed males (mean age: 22.3, ±0.4 years; laterality index [LI] of 81.25±5.22) completed two training sessions of a tracing task designed to be equally novel and challenging for each hand, separated by 24 hours. In the second experiment, 20 right-handed males (M: 21.6 ±.0.4 years; [LI]=83.24±4.1) were randomly assigned to perform this training task with either hand. The slope of transcranial magnetic stimulation (TMS) input-output (IO) curves, was used to measure change in corticospinal excitability. Results: Both hands had similar improvement of motor performance across two days of training (40% decrease in motor error for dM1 and 41% decrease for NdM1). Only the right hand significantly decreased IO curve slope over time (F (1, 18)= 1.319 with p=0.034). Conclusion: This work suggests that the dM1 may adapt more quickly to tasks equally novel for each hand which has implications for the design of rehabilitation programs and devices.

Background: Studies of autistic populations have reported several findings related to the brain pathophysiology of autism, but knowledge of the brain characteristics of younger children with autism remains limited, especially for uncooperative children. Objective: To characterize inter- and intrahemispheric brain activity in children with autism and children with Typical Development (TD) using Electroencephalogram (EEG) recordings and peak coherence spectrum extraction. Methods: We studied 9 children with autism (mean age: 6.71 years) and 10 children with TD (mean age: 6.16 years). EEG recordings were obtained under sedation according to the standard clinical procedures. We measured cortical synchrony by comparing inter- and intrahemispheric peak amplitude coherence in the 2 groups. We also compared the children who were less than 6 years old to the older children. Results: We found that compared to children with TD, children with autism had significantly more peaks in both hemispheres but equally coherent connectivity strength. Younger children with autism had fewer peaks in the sigma band (9-16 Hz) than older children with autism did. This indicated greater connectivity and was apparent both within and between hemispheres. In certain regions, younger children with TD had more peaks than older children with TD. Conclusion: Sigma band coherence is abnormally related to age in children with autism. Significance: The neural coherence differences may reflect underlying brain abnormalities in children with autism. These abnormalities may mediate their sensory, cognitive, emotional, and motor difficulties.

Background: Cognition of surface roughness at the same time by the two senses (tactile and visual) is still undeclared, and how both effects on each other could be intriguing. The main factor for roughness estimation of fine surface (spatial features below 200 μm) is also unknown until present. Objective: In order to see the difference between cognition of both condition, we conducted two unimodal and two bimodal tasks involving both modalities using fine sandpapers. Tactile stimuli consisted of six types of different sandpapers that varied in their roughness, while visual stimuli are images of the correspondence tactile stimuli Methods: In unimodal task, subjects need to compare which stimulus perceived were rougher, visually and tactually, while multiple sensory of visual and tactile were mixed in bimodal task. We also varied the type of roughness in bimodal task into two categories to discover whether there is any acceleration or suppression by different stimuli. Results: We found that tactile sensory was dominant in the perception of roughness by fine surface. During cross modalities, visual information has almost no effects toward tactile sensory, but in the other hand tactile information had significance effects onto visual sensory. Furthermore, we found that stimuli with smaller particles bring more interference into subject's perception compared to bigger particles in fine surface. Conclusion: We suggest that particles sizes are as significant as the modalities in visual, tactile, or multisensory integration of both, in roughness perception of fine surface.