Summary of “Smell Training Improves Olfactory Function and Alters Brain Structure”

The human brain retains an impressive degree of neuroplasticity, adapting to sensory experiences, learning, and training. While research has shown that sensory training can induce brain changes, little is known about how olfactory training (OT) affects both smell function and brain structure. This study by Al Aïn et al. investigates the impact of six weeks of intensive OT on both olfactory performance and neuroanatomical changes using magnetic resonance imaging (MRI).

The study recruited 36 healthy young adults (ages 18–35) and randomly assigned them to three groups: (1) an olfactory training group, (2) a visual training control group, and (3) a no-training control group. Participants in the OT group engaged in daily 20-minute training sessions for six weeks, performing three specific tasks: odor intensity classification, odor quality classification, and target odor detection. Before and after the training, all participants underwent olfactory function tests (odor detection, discrimination, and identification) and MRI scans to assess changes in brain structure.

Findings and Results

Results showed that OT significantly improved olfactory function, particularly in odor identification tasks, demonstrating intramodal transfer—where training on one task enhances performance on related but untrained tasks. Compared to the control groups, participants in the OT group showed greater accuracy and sensitivity in odor detection and identification.

MRI scans revealed that olfactory training induced structural changes in key brain regions associated with olfactory processing. These changes included increased cortical thickness in the right inferior frontal gyrus, bilateral fusiform gyrus, and the right entorhinal cortex. These findings suggest that OT enhances neuroplasticity in areas critical for odor perception, learning, and memory.

Additionally, the study confirmed that olfactory training engages higher-order cognitive functions, supporting previous research that has linked olfactory function to memory, attention, and semantic processing. Unlike previous studies that primarily focused on olfactory dysfunction, this research demonstrates that even healthy individuals can benefit from OT, both in terms of sensory perception and brain adaptation.

Neurological and Cognitive Implications

The findings suggest that olfactory processing is not isolated to the olfactory bulb and piriform cortex but also involves frontal and temporal brain regions, which are essential for cognitive functions such as memory, attention, and decision-making. This supports the idea that olfactory training could be used as a cognitive enhancement tool.

Additionally, the right entorhinal cortex—a key region affected in early Alzheimer’s disease—exhibited increased cortical thickness following OT. This suggests that olfactory training might have potential applications in delaying or mitigating cognitive decline in neurodegenerative diseases.

Study Limitations and Future Research

While the study provides strong evidence that OT can enhance both olfactory function and brain plasticity, there are some limitations. The sample size was small (n = 36), and the training duration was relatively short (6 weeks). Future research should explore longer-term effects of OT and its potential benefits for older adults or individuals with cognitive impairments. Additionally, further studies could investigate whether OT enhances white matter connectivity using advanced neuroimaging techniques.

Conclusion

This study provides strong evidence that olfactory training is an effective method for improving smell function and inducing neuroplastic changes in the brain. The findings suggest that OT could be a valuable tool for cognitive enhancement and may have therapeutic applications for aging and neurodegenerative diseases. The research highlights the interconnected nature of sensory and cognitive functions, reinforcing the idea that training one sensory modality can influence broader brain function.