A one-hour walk in nature reduces amygdala activity in women, but not in men

Can a nature walk change your brain? Investigating hippocampal brain plasticity after one hour in a forest

In cities, the incidence of mental disorders is higher, while visits to nature have been reported to benefit mental health and brain function. However, there is a lack of knowledge about how exposure to natural and urban environments affects brain structure. To explore the causal relationship between exposure to these environments and the hippocampal formation, 60 participants were sent on a one hour walk in either a natural (forest) or an urban environment (busy street), and high-resolution hippocampal imaging was performed before and after the walks. We found that the participants who walked in the forest had an increase in subiculum volume, a hippocampal subfield involved in stress response inhibition, while no change was observed after the urban walk. However, this result did not withstand Bonferroni correction for multiple comparisons. Furthermore, the increase in subiculum volume after the forest walk was associated with a decrease in self-reported rumination. These results indicate that visits to nature can lead to observable alterations in brain structure, with potential benefits for mental health and implications for public health and urban planning policies.

How does the macroenvironment influence brain and behaviour-a review of current status and future perspectives

The environment influences brain and mental health, both detrimentally and beneficially. Existing research has emphasised the individual psychosocial 'microenvironment'. Less attention has been paid to 'macroenvironmental' challenges, including climate change, pollution, urbanicity, and socioeconomic disparity. Notably, the implications of climate and pollution on brain and mental health have only recently gained prominence. With the advent of large-scale big-data cohorts and an increasingly dense mapping of macroenvironmental parameters, we are now in a position to characterise the relation between macroenvironment, brain, and behaviour across different geographic and cultural locations globally. This review synthesises findings from recent epidemiological and neuroimaging studies, aiming to provide a comprehensive overview of the existing evidence between the macroenvironment and the structure and functions of the brain, with a particular emphasis on its implications for mental illness. We discuss putative underlying mechanisms and address the most common exposures of the macroenvironment. Finally, we identify critical areas for future research to enhance our understanding of the aetiology of mental illness and to inform effective interventions for healthier environments and mental health promotion.

The role of connection with nature in empirical studies with physiological measurements: a systematic literature review

It is well described that exposure to nature reduces physiological stress, and connectedness to nature can have a moderating effect. However, few studies have so far examined the construction of the connection with nature in relation to physiological processes. In this systematic review, we collected studies that used a physiological measure and included a scale to measure connectedness to nature. Our aim was to assess the role of nature relatedness at the level of physiological processes and to summarize the results published so far. Our review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A literature search was conducted in 3 different databases (PubMed, ScienceDirect and Google Scholar). As keywords, we used all the different questionnaires that measure connectedness to nature, combined with terms related to physiological measures. After final screening, 28 articles met the inclusion criteria for the review. The studies were very diverse in terms of purpose, intervention and methods, so narrative synthesis was conducted without measures of effect. We found evidence for a mediating effect of nature connectedness on the associations between nature exposure and cognitive function, brain activity, blood pressure, cortisol level and mental health. Studies investigating nature relatedness as state-like characteristics have shown that exposure to nature increases the level of connection to nature. Eye-tracking studies have confirmed that this measurement method can be used to investigate nature relatedness at a physiological level, which could be a useful complement to self-report questionnaires in future studies.

Exercise therapy for chronic pain: How does exercise change the limbic brain function?

We are exposed to various external and internal threats which might hurt us. The role of taking flexible and appropriate actions against threats is played by "the limbic system" and at the heart of it there is the ventral tegmental area and nucleus accumbens (brain reward system). Pain-related fear causes excessive excitation of amygdala, which in turn causes the suppression of medial prefrontal cortex, leading to chronification of pain. Since the limbic system of chronic pain patients is functionally impaired, they are maladaptive to their situations, unable to take goal-directed behavior and are easily caught by fear-avoidance thinking. We describe the neural mechanisms how exercise activates the brain reward system and enables chronic pain patients to take goal-directed behavior and overcome fear-avoidance thinking. A key to getting out from chronic pain state is to take advantage of the behavioral switching function of the basal nucleus of amygdala. We show that exercise activates positive neurons in this nucleus which project to the nucleus accumbens and promote reward behavior. We also describe fear conditioning and extinction are affected by exercise. In chronic pain patients, the fear response to pain is enhanced and the extinction of fear memories is impaired, so it is difficult to get out of "fear-avoidance thinking". Prolonged avoidance of movement and physical inactivity exacerbate pain and have detrimental effects on the musculoskeletal and cardiovascular systems. Based on the recent findings on multiple bran networks, we propose a well-balanced exercise prescription considering the adherence and pacing of exercise practice. We conclude that therapies targeting the mesocortico-limbic system, such as exercise therapy and cognitive behavioral therapy, may become promising tools in the fight against chronic pain.