The Insula: An Underestimated Brain Area in Clinical Neuroscience, Psychiatry, and Neurology

Supported by recent human neuroimaging studies, the insula is re-emerging as an important brain area not only in the physiological understanding of the brain, but also in pathological contexts in clinical research. The anterior insula has a core role in supporting subjective feeling states. It can also regulate the introduction of feelings into cognitive and motivational processes. Understanding of mental conditions through multiple distinct dimensions of function associated with the insula may be important. To overcome the limitations in human neuroimaging studies, computational and statistical efforts in human brain image processing and analysis are expected. With recent technological advances in preclinical studies using rodents, we expect a better understanding of causal roles for the insula in higher brain function. Such understanding consists of the information at multiple levels spanning from the gene, molecule, cell, circuitry, physiology to behavior. Supported by recent human neuroimaging studies, the insula is re-emerging as an important brain area not only in the physiological understanding of the brain, but also in pathological contexts in clinical research. In this opinion article, we briefly introduce the anatomical and histological features of the human insula. We then summarize the physiological functions of the insula and underscore its pathological roles in psychiatric and neurological disorders that have long been underestimated. We finally propose possible strategies through which the role of the insula may be further understood for both basic and clinical neuroscience. Supported by recent human neuroimaging studies, the insula is re-emerging as an important brain area not only in the physiological understanding of the brain, but also in pathological contexts in clinical research. In this opinion article, we briefly introduce the anatomical and histological features of the human insula. We then summarize the physiological functions of the insula and underscore its pathological roles in psychiatric and neurological disorders that have long been underestimated. We finally propose possible strategies through which the role of the insula may be further understood for both basic and clinical neuroscience. an isocortical region with a relatively undifferentiated layer II and layer III, and lack of layer IV. a brain network that includes the dorsolateral prefrontal cortex and the posterior parietal cortex, which is responsible for high-level cognitive functions, such as attention and working memory. a set of all mental abilities and resources related to knowledge (e.g., attention, memory, working memory, reasoning). a brain network including the ventromedial prefrontal cortex and the posterior cingulate cortex, which is responsible for self-related activities such as autobiographical processing and self-monitoring. an approach to explore causal interactions between neural activities from time-series functional magnetic resonance imaging data. It implements a statistical, predictive notion of causality whereby causes precede and help predict their outcomes. an isocortical region with six differentiated layers, including a well-defined layer IV that contains many stellate granule cells receiving thalamocortical inputs. appetitive or aversive values assigned to stimuli that underlie particular behaviors. For example, appetitive incentive value is anticipated pleasure in particular behaviors, such as eating foods and drinking water. the perception and integration of autonomic, hormonal, visceral, and immunological homeostatic signals that collectively describe the physiological state of the body. A posterior-to-anterior progression of neural processing through the insula has been proposed: the posterior insula supports primary (objective) mappings of interoceptive signals, whereas the anterior insula supports its secondary re-representations and integration with emotional, cognitive, and motivational signals. the process of mapping body states topographically onto the central nervous system, particularly on the upper brainstem and cerebral cortex including the insula. For example, body responses elicited by thermal or visceral stimulation are mapped on subregions of the insula. Changes in these neural maps are constantly monitored and regulated for maintenance of the body’s physiology within an optimal homeostatic range. a brain network that includes the anterior insula and the anterior cingulate cortex, which is responsible for identifying salient stimuli and coordinating cognitive resources, such as attention and working memory, between the central executive network and the default mode network. the conscious perception of one’s own being. Subjective feeling states constantly updated by body states enable an awareness of the physical self. the conscious perception of body states elicited by interoceptive stimuli (e.g., thirst, dyspnea, air hunger, sensual touch, itch, penile stimulation, sexual arousal, coolness, warmth, exercise, heartbeat, wine tasting, distension of the bladder, stomach, and so on). The Insula: An Underestimated Brain Area in Clinical Neuroscience, Psychiatry, and Neurology: (Trends in Neuroscience , 200–207, 2017)Namkung et al.Trends in NeurosciencesJune 9, 2018In BriefDue to an oversight in the preparation of this Opinion article, the authors inadvertently omitted the following image credits and references [72–77]. The authors apologize for the oversight. The corrected figure legends and references [72–77] are also shown below. Full-Text PDF