Small-World Networks and Their Relationship With Hippocampal Glutamine/Glutamate Concentration in Healthy Adults With Varying Genetic Risk for Alzheimer's Disease.

BACKGROUND: Apolipoprotein E ɛ4 allele (ApoE4) is the most common gene polymorphism related to Alzheimer's disease (AD). Impaired synaptic dysfunction occurs in ApoE4 carriers before any clinical symptoms. It remains unknown whether ApoE4 status affects the hippocampal neuromodulation, which further influences brain network topology. PURPOSE: To study the relationship of regional and global network properties by using graph theory analysis and glutamatergic (Glx) neuromodulation in the ApoE isoforms. STUDY TYPE: Prospective. SUBJECTS: Eighty-four cognitively normal adults (26 ApoE4 and 58 non-ApoE4 carriers). FIELD STRENGTH/SEQUENCE: Gradient-echo echo-planar and point resolved spectroscopy sequence at 3 T. ASSESSMENT: Glx concentration in bilateral hippocampi were processed with jMRUI (4.0), and graph theory metrics (global: γ, λ, small-worldness in whole brain; regional: nodal clustering coefficient (Ci ) and nodal characteristic path length (Li )) in top 20% highly connected hubs of subgroups (low-risk: non-ApoE4; high-risk: APOE4) were calculated and compared. STATISTICAL TESTS: Two-sample t test was used to compare metrics between subgroups. Correlations between regional properties and Glx by Pearson's partial correlation with false discovery rate correction. RESULTS: Significant differences (P < 0.05) in Ci between subgroups were found in hubs of left inferior frontal, bilateral inferior temporal, and bilateral precentral gyri, right parahippocampus, and bilateral precuneus. In addition, there was a significant correlation between Glx in the left hippocampus and Ci in inferior frontal gyrus (r = -0.537, P = 0.024), right inferior temporal (r = -0.478, P = 0.043), right parahippocampus (r = -0.629, P = 0.016), left precentral (r = -0.581, P = 0.022), right precentral (r = -0.651, P = 0.003), left precuneus (r = -0.545, P = 0.024), and right precuneus (r = -0.567, P = 0.022); and Li in left precuneus (r = 0.575, P = 0.032) and right precuneus (r = 0.586, P = 0.032) in the high-risk group, but not in the low-risk group. DATA CONCLUSION: Our results suggested that healthy ApoE4 carriers exhibit poorer local interconnectivity. Moreover, the close relationship between glutamate and small-world network properties in ApoE4 carriers might reflect a compensatory response to the impaired network efficiency. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 3.

Trace Ratio Linear Discriminant Analysis for Medical Diagnosis: A Case Study of Dementia.

Dementia is one of the most common neurological disorders among the elderly. Identifying those who are of high risk suffering dementia is important to the administration of early treatment in order to slow down the progression of dementia symptoms. However, to achieve accurate classification, significant amount of subject feature information are involved. Hence identification of demented subjects can be transformed into a pattern recognition problem with high-dimensional nonlinear datasets. In this paper, we introduce trace ratio linear discriminant analysis (TR-LDA) for dementia diagnosis. An improved ITR algorithm (iITR) is developed to solve the TR-LDA problem. This novel method can be integrated with advanced missing value imputation method and utilized for the analysis of the nonlinear datasets in many real-world medical diagnosis problems. Finally, extensive simulations are conducted to show the effectiveness of the proposed method. The results demonstrate that our method can achieve higher accuracies for identifying the demented patients than other state-of-art algorithms.

Stuttered swallowing: electric stimulation of the right insula interferes with water swallowing. A case report.

BACKGROUND: Various functional resonance imaging, magnetoencephalographic and lesion studies suggest the involvement of the insular cortex in the control of swallowing. However, the exact location of insular activation during swallowing and its functional significance remain unclear. CASE PRESENTATION: Invasive electroencephalographic monitoring was performed in a 24-year-old man with medically intractable stereotyped nocturnal hypermotor seizures due to a ganglioglioma. During stimulation of the right inferior posterior insular cortex with depth electrodes the patient spontaneously reported a perception of a "stutter in swallowing". Stimulation of the inferior posterior insular cortex at highest intensity (4 mA) was also associated with irregular and delayed swallows. Swallowing was not impaired during stimulation of the superior posterior insular cortex, regardless of stimulation intensity. CONCLUSIONS: These results indicate that the right inferior posterior insular cortex is involved in the neural circuitry underlying the control of swallowing.

The cardioinhibitory responses of the right posterior insular cortex in an epileptic patient.

BACKGROUND: The insular cortex (IC) has long been implicated in the central regulation of the autonomic nervous system but its precise role remains to be determined. We studied the role of IC in cardiovascular control using a multimodality approach consisting of isometric handgrip exercises, functional magnetic resonance imaging (fMRI) activation during handgrip exercises, and direct electrical stimulations of the posterior right IC in a single patient. METHOD: A 24-year-old patient had medically intractable epilepsy secondary to a small ganglioglioma in the right posterior IC. His cardiovascular responses to 30 and 70% maximum voluntary contraction (MVC) handgrip exercises were recorded in the lab and during fMRI and compared to those of 10 healthy control subjects. He subsequently underwent stereo-electroencephalography with depth electrodes in the right posterior IC and further study of the cardiovascular responses to electrical stimulation at rest and during MVC handgrip exercises. RESULT: fMRI data showed nearly absent activation in the right IC relative to healthy subjects. At rest, electrical stimulation of the right posterior inferior IC but not the superior IC suppressed heart rate (HR) by 3 beats per minute. During exercise, the HR response to isometric handgrip contraction was weakened when the right posterior inferior IC was simultaneously stimulated. CONCLUSION: This study shows that, in this patient, the right posterior inferior IC is an important cardioinhibitory center and interference with this region alters the cardiac response to handgrip exercise. Further investigations are required to examine the cardiovascular control of the IC.

Preservice teachers' neuroscience literacy and perceptions of neuroscience in education: Implications for teacher education.

BACKGROUND: Owing to the prevalence of neuromyths in education, there has been a call for more teacher training in neuroscience. However, neuroscience is rarely featured in teacher education. This study investigated the neuroscience literacy and perceptions of neuroscience in education among preservice teachers in order to inform future development of initial teacher education. METHOD: Neuroscience literacy of 968 preservice teachers and their perceptions towards applying neuroscience in education were examined using survey items adapted from studies addressing similar constructs. Rasch item response theory and classical test theory techniques were employed for data analysis. RESULTS: Most of the preservice teachers had limited brain knowledge and subscribed to many common neuromyths but were positive towards applying neuroscience in education. General brain knowledge was the only predictor for ability to identify neuromyths (ß = .564). CONCLUSION: Neuroscience knowledge can help safeguard preservice teachers against neuromyths. Neuroscience training deserves a place in teacher education.

An evaluation of mental workload with frontal EEG.

Using a wireless single channel EEG device, we investigated the feasibility of using short-term frontal EEG as a means to evaluate the dynamic changes of mental workload. Frontal EEG signals were recorded from twenty healthy subjects performing four cognitive and motor tasks, including arithmetic operation, finger tapping, mental rotation and lexical decision task. Our findings revealed that theta activity is the common EEG feature that increases with difficulty across four tasks. Meanwhile, with a short-time analysis window, the level of mental workload could be classified from EEG features with 65%-75% accuracy across subjects using a SVM model. These findings suggest that frontal EEG could be used for evaluating the dynamic changes of mental workload.

Cross-frequency information transfer from EEG to EMG in grasping.

This paper presents an investigation into the cortico-muscular relationship during a grasping task by evaluating the information transfer between EEG and EMG signals. Information transfer was computed via a non-linear model-free measure, transfer entropy (TE). To examine the cross-frequency interaction, TEs were computed after the times series were decomposed into various frequency ranges via wavelet transform. Our results demonstrate the capability of TE to capture the direct interaction between EEG and EMG. In addition, the cross-frequency analysis revealed instantaneous decrease in information transfer from EEG to the high frequency component of EMG (100-200Hz) during the onset of movement.

Spectral modulation of frontal EEG during motor skill acquisition: a mobile EEG study.

This study investigates the modulation of frontal EEG dynamics with respect to progress in motor skill acquisition using a wireless EEG system with a single dry sensor. Participants were required to complete repeated trials of a computerized visual-motor task similar to mirror drawing while the EEG was collected. In each trial, task performance of the participants was summarized with a familiarity index which took into account the performance accuracy, completion rate and time. Our findings demonstrated that certain EEG power spectra decreased with an increase in motor task familiarity. In particular, frontal EEG activities in delta and theta bands of the whole trial and in gamma band in the middle of the trial are having a significant negative relationship with the overall familiarity level of the task. The findings suggest that frontal EEG spectra are significantly modulated during motor skill acquisition. Results of this study shed light on the possibility of simultaneous monitoring of brain activity during an unconstrained natural task with a single dry sensor mobile EEG in an everyday environment.

Spectral modulation of frontal EEG activities during motor skill acquisition: task familiarity monitoring using single-channel EEG.

This study investigates the modulation of frontal EEG dynamics with respect to progress in motor learning. Using a computerized visual-motor task similar to mirror drawing, our work demonstrated that overall EEG activities in all frequency bands decreased with an increase in motor task familiarity. In particular, frontal EEG activities in delta band of the whole trial and gamma band at the beginning of each trial are having a significant negative relationship with the overall familiarity level of the task. The findings suggest that frontal EEG spectra are significantly modulated during motor skill acquisition.

Integrating fMRI with psychophysiological measurements in the study of decision-making.

Neuroimaging techniques have recently been used to examine the neural mechanism of decision-making. Nevertheless, most of the neuroimaging studies overlook the importance of emotion and autonomic response in modulating the process of decision-making. In this paper, we discussed how to integrating fMRI with psychophysiological measurements in studying decision-making. We suggested that psychophysiological data would complement with fMRI findings in providing a more comprehensive understanding about the physiological and neural mechanisms of decision-making. Also, this technique would yield valuable information in examining the interplay among emotions, autonomic response and decision-making. The discussion is presented in a tutorial format with concrete technical recommendations for researchers who may consider to adopt the technique in their study of decision-making.