Brain and Nerve最新文献

The development of high-performance magnetic resonance imaging (MRI) scanners is ongoing. The strength of the magnetic field is the most important factor in the use of this technology. Ultra-high magnetic fields provide many benefits, including high spatial and temporal resolution. In this chapter, we describe the characteristics and images obtained using ultra-high-field MRI.

Two-photon calcium imaging is widely used to observe neural activity in animal brains. Improvements in two-photon microscopy and calcium indicators in recent years have led to higher sensitivity, faster speed, and larger field-of-view imaging, which have facilitated observation of large-scale neuronal activity in three dimensions on a micrometer to millimeter scale. In this paper, we describe these novel two-photon imaging techniques and their applications to neuroscience.

Japanese basic researchers, known for their dedication to the advancement of science without any expectation of economic benefit, are conventionally regarded as virtuous professionals. However, current social demand requires researchers to adopt a venture mindset, implement their research outcomes for societal benefit, and contribute to society through business. In this paper, I highlight the importance of overcoming the "valley of death" between society and researchers to create useful intersections between science and business, aimed at application of research outcomes to the society and encouraging a lifestyle and challenges as venture scientists who can contribute to the generation of new industries.

Positron emission tomography (PET) refers to a noninvasive imaging modality that enables ultrahigh-sensitivity quantitative evaluation of the spatiotemporal dynamics of targeted molecules within living organisms from outside the body. In this review, we explain the principles of PET imaging technology and the basic properties of ultrahigh sensitivity and quantifiability. Furthermore, we have outlined PET imaging-based integrated approaches to elucidate the fundamental neurobiological mechanisms underlying neuropsychiatric activity, as well as the usefulness of PET imaging in pharmacokinetic analysis and theranostics during drug development.

All-optical methods that provide deeper understanding of neural activity are currently being developed. Optogenetics is a biological technique useful to control neuronal activity or life phenomena using light. Microbial rhodopsins are light-activated membrane proteins used as optogenetic tools. Microbial rhodopsins such as channelrhodopsin2 (ChR2) consist of seven-pass transmembrane proteins with a covalently bound retinal. Light absorption is followed by photoisomerization of the all-trans retinal to a 13-cis configuration and subsequent conformational changes in the molecule, with consequent permeability of the channel structure to ions. Recent studies have reported the discovery of microbial rhodopsins with novel functions. Microbial rhodopsin diversity has also increased. We describe the characteristics of microbial rhodopsins used as optogenetic tools and the latest research in this domain.

The brain comprises a complex network of anatomically distinct regions (each with specialized functions) that collaborate to support various cognitive processes. Therefore, it is important to understand the brain from the perspective of a complex network. Functional magnetic resonance imaging (fMRI) is increasingly being accepted for its ability to provide useful insights into brain function. Among the fMRI techniques available in clinical practice, resting-state fMRI (rsfMRI) represents the core method for mapping brain activity in the absence of specific tasks; studies have reported the usefulness of rsfMRI in the investigation of various human diseases. Functional brain networks, which consist of interconnected regions that show correlated activities, are typically depicted as functional connectivity (FC). FC analysis using rsfMRI data provides extensive information, revealing intrinsic resting-state networks and highlights deviations in network structure among patients with psychiatric disorders. Such network insights not only deepen our understanding of the brain but also facilitate assessment of network alterations associated with psychiatric and neurodegenerative diseases.

The concept of attention in cognitive science encompasses a bidirectional nature: bottom-up attention based on the salience of sensory stimuli, and top-down attention, which involves voluntary control over aspects such as intensity, allocation, selectivity, and duration. Top-down attention is believed to be primarily realized through the frontal lobes that monitor on-going information processing. This monitoring helps detect situations requiring intervention and manipulates lower-level information processing systems as a part of executive functions.

Unilateral spatial neglect (USN) is a symptom of unilateral brain damage resulting in failure to report sensory phenomena in the contra-lesional space. It is associated with motor impairment as well as sensory deficits. Recent research suggests that USN, may be caused by a disruption in the interhemispheric balance of the visual attention network. Based on this hypothesis, non-invasive brain stimulation (NIBS), such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), is utilized in the rehabilitation of USN patients. Presently, inhibitory stimulation by continuous theta burst stimulation (cTBS) on contra-lesional parietal cortex are believed to be the most promising method. Conversely, compensation by attentional network of the non-lesioned hemisphere plays an important role in the recovery of USN. Recent imaging studies revealed that functional and structural connectivity of attentional networks within a lesioned hemisphere and between lesioned and non-lesioned hemispheres affects spontaneous recovery and effectiveness of rehabilitation approach such as prism adaptation therapy. These findings are useful in elucidating the pathophysiology of USN and predicting functional outcome. Furthermore, we hope that understanding the pathophysiology will enable the development of new rehabilitation strategies and appropriate treatment selection.

Unilateral spatial neglect is the failure of brain-damaged patients to report, respond, or orient to novel or meaningful stimuli presented to the contralateral side of the lesion. This usually involves the right cerebral hemisphere. Neglect presents with no restriction in gaze direction and results in difficulty across various aspects of daily activities, distinguishing it from simple homonymous hemianopia. The basic mechanisms underlying neglect is rightward bias of spatial attention, while non-direction-specific cognitive problems may contribute to clinical expressions of neglect.

Several evidence-based guidelines of rehabilitative intervention for attentional disturbance following acquired brain injury have been published. The author introduced two cutting-edge guidelines: Japan Stroke Society Guideline 2021 for the Treatment of Stroke [Revised version 2023]; and INCOG 2.0 Guideline for Cognitive Rehabilitation Following Traumatic Brain Injury, PartII: Attention and Information Processing Speed (2023). The effect of the cognitive rehabilitation should be evaluated by change of performance in real-world tasks and activities as well as measures of various neuropsychological tests including paced auditory serial addition task (PASAT) and trail making test. Direct attention training such as Attention Process Training (APT) series or computer-based training may be useful especially for stroke patients. Dual-task training may specifically improve multi-tasking performance. Time pressure management can improve speed of performance on everyday tasks for patients with slowed information processing. Metacognitive training using everyday activities may be recommended for mild to moderate impairments. Modifications of environment and/or tasks may also be helpful to decrease errors in daily activities.