Unraveling the True Nature of Sex Differences in Spatial Memory: A Lesson from Birds

downloadThough 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.

In a new spatial task designed by my lab to eliminate all confounding factors (see Figure), we found that female and male zebra finches showed no differences in either learning of a spatial memory or overall ability to memorize the location of a goal. Since zebra finches live in huge flocks and do not have to seek out their mates, it makes sense to see no sex difference in spatial ability and adds strength to the idea that spatial memory ability is based on the spatial memory requirements of the animal.

  1. Guigueno, M. F., Snow, D. A., MacDougall-Shackleton, S. A., & Sherry, D. F. (2014). Female cowbirds have more accurate spatial memory than males. Biology Letters, 10(2). doi:10.1098/rsbl.2014.0026
  2. Kosarussavadi, S., Pennington, Z. T., Covell, J., Blaisdell, A. P., & Schlinger, B. A. (2017). Across sex and age: Learning and memory and patterns of avian hippocampal gene expression. Behavioral Neuroscience, 131, 483.
  3. Rensel, M. A., Ellis, J. M. S., Harvey, B., & Schlinger, B. A. (2015). Sex, estradiol, and spatial memory in a food-caching corvid. Hormones and Behavior, 75, 45.

Chyna-Rae Dearman

Department of Biology

University of Mississippi

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