Pigeons Can Identify Cancerous Breast Tissue as Well as Doctors

November 20, 2015 | Joanne Kennell

Pigeon being trained to detect cancer in diagnostic images
Photo credit: Copyright Univ. Iowa/Wassermann Lab

In only 15 days, scientists trained pigeons to distinguish between cancerous and noncancerous images with 85 percent accuracy.

When most of us think of pigeons, we imagine these dopey birds cooing and hanging out on the streets of major cities, not assisting researchers in a medical lab.  Now, however, you’ll have to toss that image out the window because a study found that pigeons can accurately distinguish between normal and cancerous breast tissue.  In fact, they are just as good at it as humans.  Mind blown, right?

According to Richard Levenson, lead author of the study and professor of pathology and laboratory medicine at UC Davis Health System, “With some training and selective food reinforcement, pigeons do just as well as humans in categorizing digitized slides and mammograms of benign and malignant human breast tissue".

A pigeon’s brain is about the size of the tip of your index finger, but the study reveals that their brains work very similar to humans in how the neural pathways transmit information in the basal ganglia and cortical-striatal synapses.  "The pigeons were able to generalize what they had learned, so that when we showed them a completely new set of normal and cancerous digitized slides, they correctly identified them," said Levenson.

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According to study co-author Edward Wasserman, professor of psychology and brain science at the University of Iowa who has been studying pigeons for more than 40 years, pigeons are not limited to cancer identification. "Research over the past 50 years has shown that pigeons can distinguish identities and emotional expressions on human faces, letters of the alphabet, misshapen pharmaceutical capsules, and even paintings by Monet vs. Picasso".

The study involved “operant conditioning” of each pigeon until they learned to distinguish from cancerous and noncancerous images and slides.  They were tested using a variety of sample magnifications, monochrome and color, varying brightness, and samples with different levels of compression to rule out that the birds were looking for certain cues rather than understanding the images.  Remarkably, the accuracy on day one was 50 percent which improved to 85 percent by day 15.  What is even more impressive is that when researchers showed a group of four pigeons a set of uncompressed images, the group accuracy skyrocketed to 99 percent.

Using a similar training process, the birds were also trained to detect images with and without microcalcifications — deposits of minerals that can be an early indicator of breast cancer. Their accuracy was about 84 percent for images with microcalcifications used in training, and 72 percent for new images — a level equal to that of radiologists and radiology students who were given the same set of images.

Although the birds were very good at distinguishing between cancerous and noncancerous breast cancer slides at all magnifications, which is undoubtedly amazing, they had a more difficult time classifying abnormal masses in mammograms.  Identifying masses is not an easy task — even the most trained radiologists only achieve an accuracy rate of near 80 percent.  Unfortunately, even with weeks of training, the pigeons were never able to accurately identify suspicious masses which suggest the birds were just memorizing the masses from the training slides.

So, can pigeons be used instead of humans in the lab?  According to Levenson, "Pigeons' sensitivity to diagnostically salient features in medical images suggest that they can provide reliable feedback on many variables at play in the production, manipulation, and viewing of these diagnostically crucial tools, and can assist researchers and engineers as they continue to innovate."

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