Lack of protein can harm outward appearance, stress sensitivity, and learning by impairing brain growth and plasticity. While protein enrichment is well studied in mammals and poultry birds, little is known about protein impacts for most birds. Thus, we are studying protein enrichment in the zebra finch, a common avian lab model because its song learning mimics human language learning. While zebra finches mainly eat seeds, protein is increased by consuming insects and young seeds, especially during breeding, and may be beneficial in captivity.
A poor diet results in an unhealthy appearance in humans? Normally, female zebra finches are attracted to males with big, bright, red cheek patches. Since low protein may reduce attractiveness, we will quantify the size and color of male cheek patches and test mate preferences of birds on low and high protein diets. We expect males and females will prefer to associate with mates fed high protein diets.
Ever go on a fad diet and find yourself irritated and jumpy? If a healthy diet lowers stress in zebra finches, baseline and reactive stress hormone levels, the latter induced by holding birds in a breathable cloth bag for 30 minutes, will be lower when fed high protein.
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| The Escape Maze | Fear Conditioning Chamber |
We will test two forms of learning: spatial learning and classical conditioning to determine if, like mammals, protein aids learning. The Escape Maze tests birds’ spatial learning, the ability to store and recall locations. We test spatial ability by seeing how many trials it takes for birds to learn to escape a clear cylinder using visual cues hanging around the maze to triangulate the escape hole’s position. In Fear Conditioning, birds are placed in a box, a tone plays, and a small shock is delivered. Birds should learn to take flight to avoid the shock when they hear the tone, similar to Pavlov’s dogs salivating when a bell rang. We expect that a high protein diet will help birds learn at a faster rate than a low protein diet.
After behavioral tests, we will determine if high protein aided brain growth and plasticity in the areas of the brain involved in anxiety, spatial ability, and fear conditioning. If protein has positive impacts, we suggest all lab zebra finches be providing protein supplementation. Such results would suggest that despite inconsistent protein in the wild, zebra finches, like mammals, have an evolutionarily conserved benefit from protein, the building block of life.
Citations:
- Bonaparte, K. M., Riffle-Yokoi, C., & Burley, N. T. (2011). Getting a Head Start: Diet, Sub-Adult Growth, and Associative Learning in a Seed-Eating Passerine. PLoS ONE, 6(9). https://doi.org/10.1371/journal.pone.0023775
- Burley, N. T., Hamedani, E., & Symanski, C. (2018). Mate choice decision rules: Trait synergisms and preference shifts. Ecology and Evolution, 8(5), 2380–2394. https://doi.org/10.1002/ece3.3831
- Paula-Barbosa, M. M., Andrade, J. P., Castedo, J. L., Azevedo, F. P., Camões, I., Volk, B., & Tavares, M. A. (1989). Cell Loss in the Cerebellum and Hippocampal Formation of Adult Rats after Long-Term Low-Protein Diet. Experimental Neurology, 103, 186–193.
Belinda Bagwandeen
PhD Student, Day Lab
Biology
It is no secret that everyone ages. Humans do not stay frozen at a specific age. They age, and when they age there are declines in processes such as metabolism and cognition. A recent study investigated why there may be a loss of cognition with age. One answer is the length of the telomere!
Ischemia is a condition characterized by insufficient blood flow, which causes a shortage of oxygen that is necessary for cellular metabolism; therefore, ischemia leads to dysfunction and death of cells including neurons. CART expression after ischemia reduced neuronal cell death and DNA damage by 37-59% (see Figure). CART-related neuroprotection was greatly increased by the presence of estradiol. Further, CART inhibition reduced the neuroprotective effects of estradiol. Therefore, CART is believed to be an important component in estradiol-mediated neuroprotection.
Imagine a wild dog is running towards you and there is no escape. You are helpless and will have to face the consequence of the attacking dog. Now imagine that you are standing in an open doorway. Now you know that you have control of the situation and can prevent the dog from attacking you by closing the door. In this hypothetical example of the wild dog, how does your brain respond the moment it knows you have control over the outcome of the situation? Currently, few studies have compared the brain’s response to cues indicating aversive (or rewarding) events in uncontrollable and controllable circumstances.
One of the primary ways we learn a new skill is through our teachers providing feedback in the form encouragement or criticism. This feedback is very valuable to learning and is meant to incentivize the learner to improve their upcoming performance. But are there some types of feedback that can hinder to skill learning? Recently, researchers have focused on how reward and punishment affect skill learning and retention. These studies demonstrate that punishment feedback enables faster learning but diminishes task preservation. Whereas reward feedback, promotes both learning and retention (1). Additionally, reward and punishment feedback activate different areas of the brain (2). Collectively, these studies suggest reward and punishment have distinguished effects behavior and our brains. However one question still remains: How are these types of feedback actually changing our brain during the process of learning and retention? Currently, no study has looked at how reward and punishment affect the moment to moment processes of the brain after receiving the feedback.
Though we come to realize more and more how similar we are to one another, there remain certain slight differences between sexes across the animal kingdom. In humans and other mammals like mice and monkeys, many studies have revealed a sex difference in spatial memory. Spatial memory is how you know where things are in relation to yourself and other things, whether they be objects, places, or other people, and the ability to use this information to navigate yourself wherever you want to go. It appears that while overall spatial memory performance is similar between sexes, males have an initial upper hand due to the use of more efficient strategies to acquire a new spatial memory. The reason for this difference seems to be the simple fact that male mammals use their spatial memory more than females, most often for seeking out females across their territory. This reflects a property of the brain that many refer to as “use it or lose it” but that might be more accurately put as “don’t need it, don’t develop it,” though not quite as catchy. In birds, this feature of spatial memory can be seen even more clearly. For example, brown-headed cowbirds are brood parasites such that the female seeks out suitable host nests in which to lay her eggs and then remembers the location of the nest until she is ready to lay. In these birds, females perform better on spatial memory tests than males, who do not participate in the nest seeking (1). In two other studies on birds, there were some slight differences in how males and females learned a new spatial memory but overall performance was the same (2, 3). However, there were many outside factors involved in these tasks that could have affected the birds’ ability to learn.