Pollination Under Pressure: Grazing and Nutrient Enrichment Reshape Arctic Pollinator Communities and Interaction Networks.

Alzheimer’s Disease (AD) is the most common form of dementia worldwide, characterised by specific neuropathological changes and a gradual decline in cognitive, behavioural, and functional abilities []. Extensive research has focused on identifying specific biomarkers during the presymptomatic phase to enable early diagnosis of the disorder []. Several studies have also examined the neuropsychological impairment in the earliest stages of the disease. Patients with AD typically exhibit a distinctive pattern of cognitive decline predominantly involving episodic memory []. This pattern aligns with evidence indicating that the medial temporal lobe, particularly the perirhinal and hippocampal regions, is among the brain regions most susceptible to the initial neuropathological alterations associated with AD []. Although episodic memory impairment is widely recognised as one of the most robust and predictive cognitive markers of conversion to AD in its prodromal stages, its diagnostic specificity remains limited, as similar impairments are also observed in a range of other neurodegenerative disorders []. Consequently, there is growing interest in identifying additional cognitive markers as promising hallmarks for the early identification of individuals at risk of developing dementia. Spatial navigation abilities are gaining recognition as a cost-effective cognitive marker for identifying AD in its preclinical stages [–]. Indeed, navigational difficulties involving egocentric and allocentric representations of the environment have been described in preclinical AD and MCI [–]. Egocentric navigation relies on route-based representations anchored to the individual’s body, whereas allocentric navigation involves survey-based representations that encode spatial relationships between landmarks independently of the observer’s position []. Findings regarding the relative involvement of egocentric and allocentric strategies in preclinical and prodromal AD remain inconsistent. Allison and colleagues [] reported selective impairments in allocentric wayfinding in individuals at preclinical stages of AD, whereas Weniger and colleagues [] observed pronounced deficits in egocentric navigation and route-based strategies in patients with amnestic MCI. Fewer studies have examined the effects of AD and MCI on other spatial representations. Following the conceptual distinction proposed by Tversky and colleagues [], different types of space can be identified: the navigational space, the space around the body, and the body space—the latter being experienced both internally, through interoception, and externally, through exteroception.