So, let's start with mice. The most famous kind of maze for mice these days, especially in dealing with the hippocampus, is called the Morris water maze. It's basically a round swimming pool filled with water, with a hidden platform that allows the animal to escape. When a rodent engages its hippocampus, it actually switches from a sort of random strategy of looking at the hidden platform to swimming directly to the hidden platform no matter where it was put into the swimming pool.
But what about the human maze? These days, we like to [study brains] in brain scanners. So we have to use virtual-reality goggles and we can create an entire town, like the city of London, for example, using [these] goggles. The human subject is in a functional MRI scanner, and they can navigate themselves around the city of London. If you think about the environment we find ourselves in every day, the work environment or home environment, and the environment between those two places, unless they are the same, that represents a maze that's changing every single day.
It's quite a complicated maze, if you think about it. I'm 15 miles from my house right now, and I've got a very busy urban area that I have to navigate home. It's potentially different every day. If you're not trained on that maze, it's very difficult for you—even if you have signs saying "This way to Washington, D.
On the other hand, if you've lived in Washington for 25 years, you don't even have to think about it. Humans can solve a maze using a number of strategies. One such strategy is to take note of environmental cues [such as the position of the stars at night]. Another strategy is to use a salient cue [like a big red ball hanging directly over a goal box] or, for certain mazes, a very simple strategy such as only taking right-hand turns works.
All rights reserved. As a neuroscientist, how do you define a maze? Both your parents were also neuroscientists. Did this shape your own interest in the brain? What kind of mazes exist outside of the laboratory, in everyday life? What strategies do humans use to solve mazes? This interview has been edited and condensed. Share Tweet Email. Video-based mazes and software are also available from such companies as Clever Sys in Reston, Virginia, and Noldus in Wageningen, the Netherlands.
Scientists often have to fiddle with settings including lighting and visual contrast to get video-tracking software to work, Rhodes says. And they must measure how accurate their systems are at recognizing behaviours. It took about six months for the group to feel confident with the system, says Cotella. IntelliCage fits inside any conventional lab cage. Each of its four corners houses devices that can run rodents through some of the tests they might experience in mazes — for example, they might receive an unpleasant puff of air in one place, but not others.
Each corner can also be keyed to respond only to specific animals, so that different rodents undergo different tests. The ability to keep multiple mice in one cage is a plus, notes behavioural neuroscientist David Wolfer of the University of Zurich in Switzerland, because they are social animals.
For instance, it cannot detect when an animal rears up on its hind legs. But Oettler counters that video analysis is more open to observer bias in terms of interpreting results.
Behavioural scientists have also automated dietary monitoring. Kravitz, for instance, investigates obesity by tracking mouse food intake and activity levels.
But because mice eat very little, even tiny mistakes in measurements can throw results off, he says. But it can have a high price-tag, making studies of many animals at once economically impractical.
Instructions are available on OpenBehavior, a site co-founded by Kravitz that is dedicated to open-source behavioural-science projects.
But, cautions Kravitz, do-it-yourselfers are usually on their own if the system has technical hiccups. At Western University in London, Canada, cognitive neuroscientists Tim Bussey and Lisa Saksida have developed chambers containing touchscreens, which researchers can use to test rodents on 20 or so cognitive tasks, covering memory, learning, attention and even gambling.
Alternatively, researchers can use software called the Animal Behavior Environment Test System to program their own tasks, says Bussey. These exploratory turns can be seen in traces that were captured from above. The tracking, in this case, is not unlike. Instead of a motion sensing camera above the maze, Theseus carried a small lamp and was photographed at long exposure to capture the trace.
Shannon originally developed Theseus in an effort to further understand how the technology that drove those old telephones carried information, so that, ultimately they could make it better and more efficient.
The mouse in a maze is truly an apt metaphor to connect this endeavor to behavioral science. When Dr. Willard Small first published the rodent maze, he wanted to understand the mental processes of the rat during natural behaviors. How does the brain, with its finite number of cells, synapses, and neurotransmitters, possess the ability to produce and transmit such an incredibly wide array of information?
We are still using mazes to understand how a real, living animal processes information and makes decisions. Figure 5: A photographed trace of Theseus exploring a maze [4].
Claude Shannon recognized the potential of merging new technology with established protocols to investigate new questions. The use of animal models for studying human physiology enjoys a long history — over thousands of years [5]. Relatively speaking, mazes are still rather new, having only been adopted just over a century ago. However, the scientific world moves rapidly when it comes to methodologies.
The cutting-edge technology one day could be considered outdated ten or fifteen years down the line. Yet the maze is still commonly employed by behavioral scientists to this day, due in no small part to its flexibility to be adapted to modern work. The employment of the rodent maze as a scientific method has two foundational levels of flexibility that have allowed it to keep pace with the times. The first level has to do with the maze itself.
A great many varieties of maze exist today for use in rodent research, each specifically designed to probe distinct behavioral traits. The capacity to design a maze to suit specific scientific inquiries has been appreciated almost since the dawn of its creation; Dr.
Hunter exemplified this concept as he adapted his simple and double alternation mazes into three dimensions. Claude Shannon, among other options. For more straightforward decision-making studies, a T-maze or Y-maze may be the right fit for the experiment. Even more effective processes have mazes designed to investigate their biological and psychological underpinnings. Anxiety, for example, can be quantified more or less in rodents using elevated plus or zero mazes.
The second key aspect of rodent mazes that have rendered it an enduring technique are the rodents themselves. The mouse particularly has become a fixture, not only in behavioral science but in biological research more broadly. Due to the impressive technological advancements that have been made with the mouse, the mouse is an applicable model organism to an incredible variety of studies.
One could fill an encyclopedia with the amount of knowledge we have collected about mouse behavior and physiology as well as its precise genome. It is hard to adequately describe how essential the full characterization of the lab mouse genome is to expanding the boundaries of feasible research.
This knowledge has enabled us to map behaviors onto specific genes that have then been relevant to human physiology. For example, this command of the mouse genome allowed scientists to map disrupted circadian rhythms onto a gene we now call Clock.
Just this year, the value of such work investigating the mechanisms controlling circadian rhythms was recognized with the Nobel Prize in Physiology or Medicine.
Our fluency in the mouse genome has also allowed scientists to manipulate the genome to create superior models of human disease. Such mice are regularly characterized using a battery of behavioral tests , often including mazes, to assess the effect of these human genes in behavior and disease progression.
Scientists have also developed tools that allow them to manipulate mouse brain functions in ways that can be temporally controlled. Some of these tools, such as optogenetics , allow a scientist to promote or inhibit the firing of a neuron on a near-immediate timescale by shining a laser onto a part of the brain that has been engineered to express genes that will respond to that particular wavelength of light. Mice engineered with DREADDs have unique receptors in specific areas of their brains that work like a lock and key; certain cell types are given this distinct lock the DREADD , and those locks can only be opened by one key a specific drug administered by the scientist.
Animals engineered for optogenetic or DREADD experiments often undergo behavioral characterization to see what the impact of manipulating those brain cells will have. For example, a scientist could train a mouse engineered for an optogenetic test to run a maze until it has mastered it.
Then, the scientist could place the mouse at the start but this time turn on the laser in an area crucial for spatial navigation, like the hippocampus.
Suddenly, the mouse may forget where it must go, highlighting the importance of this brain region for spatial navigation. Scientific tools are constantly developing and changing. The cutting-edge technology of one day can be rendered obsolete by progress just a decade later.
The methods that stand the test of time are the ones that can address fundamental questions in versatile ways and evolve with time. Over the last century, scientists have shown that mazes possess exactly those qualities. While the bells and whistles appended to the rodent maze have changed with time to meet growing scientific demands, the fundamental aspects of the maze have remained relevant and valuable with the passage of time. How can we be helpful? Close Search. History of Mazes.
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