Brain and Nerve最新文献

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.

Classical evidence for neural mechanisms of attention resulted from findings that attention to sensory signals modulated sensory neuronal responses in both humans and non-human animals. These findings led scientists to propose a variety of sophisticated information-processing and mathematical models of attention. Recent advances in neuroimaging and studies including hemispatial neglect and attention deficits in patients have also facilitated understanding of neural mechanisms of attention in terms of functional specialization and large-scale brain network. Here, we reviewed neural mechanisms of attention from classical literature up to recent advances.

Diagnosis of ADHD in adulthood is increasing rapidly in Japan. The ADHD symptoms occur on a continuum with those of normal development and are likely to fluctuate with the growth process and environment at the time of diagnosis. Especially in adult cases, comorbid psychiatric disorders tend to influence the characteristics of ADHD. ADHD has diverse clinical manifestations and a heterogeneous biological background. In addition to the RDoC approach to elucidate the pathogenesis and etiology of the disorder, we expect that attempts will be made to classify the disorder into relatively homogeneous biological subcategories.

The subcategories of attention function have various classification methods. In this section, we have listed subcategories that are easily applicable to neuropsychology, namely selective, sustained, spatial, and divided attention, attentional inhibition, and attention shifting. Among them, selective attention is a function excluding unnecessary information from a myriad of data while selecting essential information. Sustained attention, in contrast, is a function directing attention to information over a certain period and maintaining it during task execution, are the two basic subfunctions in attention. Attentional inhibition, divided attention, and attention shifting are regarded as attentional control functions or executive control of attention, which are closely related with working memory and executive function. However, there is also an overlap observed among these subfunctions. Since our cognitive activities are intertwined with attention functions, it is challenging to purely extract specific attention functions.

Impairment of attention, especially complex attention, appears in the early stage of dementia. Complex attention is one of the six neurocognitive domains, which are disturbed in dementia. Impairment of complex attention promotes symptoms of dementia, difficulties in activities of daily living (ADLs), and disturbed communication in dementia due to Alzheimer disease, Lewy body disease, and cerebrovascular diseases. Despite its importance, research on "impairment of attention in dementia" is scarce. We look forward to future studies addressing this topic. In this article, we emphasized on providing care for ADL and communication for people with dementia, who have attention deficits.

The aggregation of α-synuclein (α-syn), associated with Parkinson's disease (PD) extends from the peripheral autonomic nervous system to the cerebral cortex, indicating a neural circuit-based mechanism of spread. However, recent studies, have proposed alternative propagation routes beyond neural pathways, including transmission via bodily fluids, such as the blood. This notion expands our understanding of PD progression, underscoring the complexity of α-syn spread and its implications in disease management and therapeutic strategies.

Visual search is a useful experimental paradigm investigating various aspects of attention. For efficient search, participants must avoid revisiting previously viewed objects. Inhibitory tagging and inhibition of return are phenomena related to this process, but their neural mechanisms are yet to be elucidated. Recent studies have shown that the rate of revisit behavior during visual search correlates with working memory capacity. This suggests that top-down signals from the frontal executive system alter the priority map that guides attention and eye movements. With this in mind, we have developed a novel visual search paradigm with many identical distractors and an evaluation model that assesses multiple parameters of working memory. The model incorporated memory capacity, memory decay, and utility rate, and when applied to data obtained from experimental animals, these parameters could be reliably evaluated. Furthermore, using the behavioral paradigm and model, we found that systemic administration of subanesthetic dose of ketamine decreased utility rate and memory capacity, while nicotine administration increased utility rate. Since our behavioral paradigm does not require complex instruction, it can be applied to a variety of patients in future clinical studies.