Environmental enrichment (EE) is a key strategy for enhancing animal welfare by promoting adaptive capacities across multiple functional systems, including behavior, immunity, and metabolism. In companion animals, enrichment improves emotional stability and mitigates behavioral issues; in farm animals, it enhances adaptability to intensive handling and housing systems; in laboratory animals, it reduces stress-induced physiological responses that may bias experimental outcomes; and in wildlife under human care - such as in zoos - it facilitates the expression of natural behavioral repertoires, reducing stereotypies and improving overall health.

In all these contexts, enrichment strengthens functional capacity, defined as the ability of biological systems to buffer environmental perturbations. This buffering capacity underpins resilience - the animal’s ability to maintain or restore physiological and behavioral stability in response to environmental challenges. In a world where human-animal interaction is increasingly close and constant, implementing environmental enrichment strategies is essential not only to protect physical health, but also to promote mental well-being. Ethically and scientifically, it is imperative to assess and mitigate negative emotional states such as fear, anxiety, frustration, or emotional pain in order to achieve a truly holistic approach to animal welfare.

This Research Topic aims to compile innovative studies that explore environmental enrichment as a neuroethological strategy to promote mental health, positive affective states, and well-being in companion animals, farm animals, laboratory animals, and wildlife under human care (zoos, sanctuaries, and conservation units). An integrative perspective will be emphasized, focusing on the relationship between environmental stimulation and the functional capacity of the animal to respond adaptively to its environment. We especially welcome contributions grounded in neurobiological, physiological, behavioral, and health-based approaches, with a particular focus on resilience, emotional regulation, and the mitigation of negative affective states such as fear, anxiety, frustration, emotional pain and distress.

This collection will prioritize studies that apply non-invasive assessment tools, including artificial intelligence for analyzing facial expressions and body language, infrared thermography, remote physiological monitoring, telemetry, motion-detecting cameras, triaxial accelerometry, GPS collars with activity sensors, automated systems for recording rumination, respiratory rate and heart rate, dynamic weighing platforms, bioacoustics for vocalization analysis, and integrated wearable devices. These technologies allow for the objective, non-intrusive quantification of multiple indicators of both physical and emotional welfare. This initiative seeks to generate solid, multidisciplinary evidence on effective enrichment strategies to support the development of ethical, sustainable, and scientifically validated practices that promote authentic animal welfare in increasingly complex human-animal interfaces.

Key thematic areas include:

• The human as a generator of positive and negative emotional states in animals
• Neurobiological plasticity induced by enrichment: neurogenesis, synaptogenesis, and functional remodeling
• Environmental regulation of the hypothalamic-pituitary-adrenal (HPA) axis
• Interactions between environmental enrichment, resilience, and systemic functional capacity
• Neurodevelopment in enriched contexts: epigenetic and cognitive effects
• Positive affective states and their biomarkers
• Play, exploration, and affiliative behaviors as expressions of emotional welfare
• Prevention of chronic distress through targeted environmental stimulation
• Non-invasive assessment: facial expressions, body posture, behavior, thermal responses, pupillary metrics
• Bioacoustics and the analysis of non-verbal animal communication
• Remote welfare monitoring: physiological sensors, accelerometry, infrared thermography, GPS, and wearable technologies
• Integration of enrichment into the Five Domains model of animal welfare
• Cognitive-emotional enrichment through positive reinforcement training
• Individualized enrichment programs based on neuroethological profiles and personality traits
• Gut-brain-microbiome axis: impact of enrichment on systemic health and emotion
• Enrichment as a tool in animal models of neurological injury: stroke, perinatal ischemia, hypoxia
• Enrichment for neurorehabilitation and neuroprotection
• Evidence-based enrichment strategies in laboratory, farm, companion, and captive wild animals
• Limitations and benefits of enrichment across mammals, birds, and fish
• Multimodal enrichment design: sensory, social, cognitive, physical, and feeding-based stimulation
• Ethical and scientific justification of enrichment as a biological need in companion animals
• Legal frameworks and policy perspectives on environmental enrichment

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Environmental Enrichment: Neurobiology, affective states, and positive animal welfare