How Taste Works on The Tongue:
How taste works in the brain:
“Tastants,” or chemicals in foods, are picked up by taste buds, which are located on the tongue and are also called papillae. We have between 5,000–10,000 taste buds and each one has between 50–100 specialized sensory cells.
When the sensory cells are stimulated, they transmit signals to the ends of nerve fibers, sending impulses along cranial nerves to taste regions in the brainstem. From here, the impulses are communicated to the thalamus and on to the cerebral cortex, thus accounting for our conscious experience of taste.
The olfactory bulb is located within this region of the brain, which is responsible for the conscious experience of smell. You’ll note that when you have a cold, or hold your nose, food tastes different. This is because the two systems work in tandem.
For a much longer review, please see How Stuff Works: How Taste Works (http://science.howstuffworks.com/life/human-biology/taste4.htm)
Where Do We Experience Pleasure in the Brain ?
Reward Circuits in the Brain:
Image Credits: Thanks to Gary Lange, PhD for this wonderful image- the brain diagrams can be a little abstract, but this helps clarify the issue significantly.
Affective neuroscientists are currently careening through the brain, mapping locations that identify where pleasure is experienced. In addition to general brain research, this element of study helps explain key aspects of human motivation.
We are gaining increased insight into the way pleasure is felt in the brain: what kinds of activities can cause corrosive damage (the end result of which is brain atrophy) versus those that stimulateneurogeneration and longer term brain health.
Significant research is devoted to understanding the precise locations of pleasure circuitry within the brain. How, where, and why we experience pleasure is important in the context of addictive and eating behaviour. Why we eat too many biscuits in place of fruits and vegetables is an exceedingly complex question, and we are only beginning to gain real insights into this fascinating realm of science.
If used in a compulsive way, both food and rewarding substances can cause neuro-degeneration. Changes in brain plasticity can be the result of chronic over stimulation. Over stimulation is the result of overeating or ingestion of ‘hyper’ palatable foods. Significant advances in neuroscience has allowed us to gain key understanding of brain systems responsible for creating the feeling of pleasure, and new research is devoted to uncovering healthy stimulation of the brain to induce neuro-generation and brain growth.
Pleasure Pathways in the Brain
In the broadest sense, understanding the neural circuitry of pleasure can provide a key insight into how the brain works. We do a lot of things because they ‘feel good’; identifying the neural origins of pleasure lends fascinating insight into the human brain and motivation.
Advances in neuroscience research have begun to illuminate some of the locations of where pleasure is experienced in the brain. With animal surgery, researchers have found the ventral pallidum and the nucleus accumbens each contain ‘hedonic hot spots’ for taste rewards. Here is where activation of u-opioid receptors occurs. The activation of these receptors causes an increased feeling of pleasure when we taste sweet foods, which can be seen when babies smile upon the ingestion of sucrose. The pleasure centers in the accumbens and pallidum interact with one another in their opioid-mediated heightened sense of ‘liking’ with reactions to sweetness. Those limbic hot spots have connections to other potential hot spots distributed elsewhere in the brain, which then contribute to your decision to seek, find, and eat high fat high sugar foods.
This is what pleasure centers look like within the rats’ cortex:
click to enlarge – Taken from Kringelbach, 2010 ‘Functional Neuroanatomy of Pleasure and Happiness’ (Discovery Medicine, http://www.discoverymedicine.com/Morten-L-Kringelbach/2010/06/25/the-functional-neuroanatomy-of-pleasure-and-happiness/)
What Else Elicits Pleasure?
While there are numerous activities that elicit pleasure (from social interaction, to shopping, to travel) researchers have unanimous accord on the importance of physical exercise. It is hugely important in brain health! For more specific information, please see this post. In brief, exercise elicits endorphins, Brain Derived Neurotrophic factor, enhances insulin profiles, and can reduce impulsivity. For these reasons, it needs to be included in your daily routine; impulsivity alone is a huge precursor to problematic relationships with food and drugs. By engaging in physical activity you may diminish depressive affect and lift your mood through natural means. If you are having chronic issues with mood regulation, please seek help from your physician.
With the information here, I hope you have gained a greater understanding of how food and pleasure interact to stimulate your brain. For further insights into your own eating motivation please see the self reports quizzes or my blog for greater detail.