Back to all research

Functional imaging of gustatory perception and imagery: “top-down” processing of gustatory signals

DOI: 10.1016/j.neuroimage.2004.08.002
Kobayashi, M., Takeda, M., Hattori, N., Fukunaga, M., Sasabe, T., Inoue, N., Nagai, Y., Sawada, T., Sadato, N., & Watanabe, Y. (2004). Functional imaging of gustatory perception and imagery: “top-down” processing of gustatory signals. NeuroImage, 23(4), 1271–1282. doi:10.1016/j.neuroimage.2004.08.002

Abstract

By recalling gustatory memories, it is possible to generate vivid gustatory perceptions in the absence of gustatory inputs. This gustatory image influences our gustatory processing. However, the mechanism of the "top-down" modulation of gustatory perception in the human is still unclear. Our findings propose a new perspective on the neural basis of gustatory processing. Although gustatory imagery and gustatory perception shared common parts of neural substrates, there was an asymmetrical topography of activation in the insula: the left insula was predominantly activated by gustatory imagery tasks. In addition, the middle and superior frontal gyri were not activated by gustatory perception but they participated in the generation of gustatory hallucinations. These regions in the frontal cortex may mediate the "top-down" control of retrieving gustatory information from the storage of long-term memories.

Authors

  • Masayuki Kobayashi2
  • Masaaki Tanaka2
  • Noriaki Hattori1
  • Masaki Fukunaga1
  • Tetsuya Sasabe2
  • Noriko Inoue1
  • Yasuo Nagai1
  • Tohru Sawada1
  • Norihiro Sadato1
  • Yasuyoshi Watanabe2

Understanding How Our Brain Processes Taste: A New Perspective

Overview/Introduction

Have you ever imagined the taste of your favorite food without actually eating it? This ability to recall tastes vividly is known as gustatory imagery, and it plays a crucial role in how we process taste. Recent research has explored how our brains manage this "top-down" process, where memories influence our perception of taste. This study sheds light on the brain regions involved in gustatory processing and how they interact to create taste perceptions, even without direct taste input.

Methodology

The study involved 25 healthy Japanese volunteers, aged 21-31, who participated in experiments designed to explore both gustatory perception (actual tasting) and gustatory imagery (imagining tastes). Using advanced brain imaging techniques, researchers measured brain activity while subjects tasted different fruit juices and imagined various tastes. The experiments were conducted using a specialized system to deliver taste solutions without requiring swallowing, and brain activity was recorded using a 3.0-Tesla MRI scanner.

Key Findings

  • Shared Brain Regions: Both actual tasting and imagined tastes activate similar brain areas, particularly the insula, a region deep within the brain.
  • Asymmetrical Activation: The left insula showed more activity during gustatory imagery, suggesting it plays a key role in processing imagined tastes.
  • Frontal Cortex Involvement: The middle and superior frontal gyri were active during gustatory imagery but not during actual tasting. This suggests these areas are involved in retrieving taste memories and generating imagined tastes.
  • Top-Down Processing: The study suggests that the frontal cortex helps control the retrieval of taste information from long-term memory, influencing how we perceive taste.

Implications

These findings provide a deeper understanding of how our brains process taste, highlighting the significant role of memory and imagination. This research could have practical applications in areas such as:
  • Food Industry: Enhancing flavor experiences by understanding how taste memories influence perception.
  • Therapeutics: Developing treatments for taste disorders by targeting specific brain regions involved in taste processing.
  • Cognitive Training: Using gustatory imagery exercises to improve memory and cognitive function.

Limitations

While the study provides valuable insights, it is limited by its small sample size and specific demographic (young, healthy Japanese adults). Future research could explore diverse populations and investigate how different factors, such as age or cultural background, influence gustatory processing.
In summary, this research offers a new perspective on how our brains create and process taste experiences, emphasizing the powerful role of memory and imagination in shaping our perception of flavors.