The Gustatory System

Basic Anatomy

The sensory system of taste consists of food being dissolved in saliva, and stimulating the taste receptors of the taste buds.

Taste Buds are located in the papillae, and each bud contains 50-150 receptor cells (that are replaced every 10-11 days).

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Signals from taste receptor cells travel along various cranial nerves. These pathways first synapse in the brain stem, and then in the thalamus, before terminating in areas in the frontal lobe (including the orbitofrontal cortex).

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Uniform Distribution of Receptors

The distribution of taste receptors across the tongue is even, meaning there is no 'sweet' or 'salty' sections.

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We are not equally sensitive to each of the five kinds of taste, our detection thresholds differ dramatically;

  • Sweetness we detect 1/200
  • Saltiness 1/400
  • Sourness 1/130,000
  • Bitterness 1/2,000,000
  • Umami (pleasant savoury) is currently unknown.

The sense of taste features importantly in the development of a complex emotion of disgust. Some taste fibres directly link to the amygdala and the hypothalamus (hence the emotional connection and reward functions). We are, however, able to overcome our aversion to some bitter/sour flavours with practice - adaptability.

Hard-Wiring of Responses

Similarly to olfactory responses, newborns show similar reactions to sweet/bitter/sour (although less to salty) as do adults. Other mammals do similar.

Beauchamp, Cowart, & Schmidt measured this in 1991.

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Tasters v Super-Tasters

Based on reaction to PROP (a bitter-tasting chemical formulae; 6-n-propylthiouracil), we can identify that some people have an above-average experience of taste intensity. These super tasters are more likely to be women, and those of non-caucasian descent. The reason is currently unknown, but the number of fungiform papillae is suspected to be relevant.