Brain and heart responses to real vs. artificial flowers in elderly women
image: An elderly woman participates in horticulture therapy while brain measurements are taken to assess neural responses.
Credit: Osaka Metropolitan University
Horticultural therapy is widely used in geriatric care, yet the neurophysiological mechanisms distinguishing natural from artificial plant materials remain inadequately characterized.
An Osaka Metropolitan University-led research team conducted a within-subject crossover study, which examined electroencephalographic (EEG) source activity and heart rate variability (HRV) in 29 community-dwelling elderly women (mean age, 77.66 ± 3.71 years) during flower arrangement (FA) tasks using fresh and artificial flowers. A subset of 16 women (mean age, 78.13 ± 3.30 years) provided sufficient artifact-free HRV data. EEG source localization using exact, low-resolution electromagnetic tomography with statistical nonparametric mapping revealed a significantly greater current source density in the left frontal lobe delta band (2–4 Hz) during AQ3 fresh vs. artificial FA, localized at the Montreal Neurological Institute coordinates (X, Y, Z) = (–20, 60, 25 mm).
The fresh-flower condition also elicited significantly higher cardiac vagal index values, indicating a medium-to-large effect on parasympathetic activity. No significant difference appeared in the cardiac sympathetic index. Although frontal delta enhancement during tasks is traditionally associated with drowsiness or reduced cortical efficiency, converging evidence suggests context-dependent roles in homeostatic and motivational processes. The left-sided localization is a pattern that has been associated with approach-related neural systems in the alpha-band literature, although extrapolation to delta oscillations remains speculative. This finding may suggest the possible engagement of motivational processing alongside parasympathetic relaxation, but alternative interpretations, including mild hypoarousal, cannot be excluded.
These findings are consistent, but do not uniquely confirm the biophilia hypothesis or approach motivation, and alternative interpretations including mild hypoarousal remain plausible. Nonetheless, the results provide preliminary neurophysiological corroboration for the therapeutic value of authentic botanical materials in horticultural interventions for elderly populations.
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