This protocol follows any and all animal care and use guidelines and regulations set by IACUC at the University of Cincinnati. This work is funded by NIH/NINDS NS07722 and the Gardner Family Center for Parkinson&#8217;s Disease and Movement Disorders.

All steps of the protocol follow the animal care and use guidelines and regulations set by the IACUC of the University of Cincinnati.
1. General Considerations
<ol>
	<li>If possible, test mice during their active phase in the dark cycle. Typically, perform testing under low light and at least 1 hr into the dark cycle. However, if testing in the dark cycle is not feasible, perform all three tests during the light cycle. Keep in mind that sniffing times may decrease when mice are tested during their sleep cycle. NOTE: While the tests can be performed during the sleep cycle the mice may show less interest in the buried pellet, blocks, or scented cartridge.</li>
	<li>In order to reduce any effect of outside olfactory cues, wear a base pair of gloves at all times throughout each test and then place a clean pair of gloves over the base pair for each mouse and each trial. As a general rule, when in doubt, put on a clean set of gloves. Have a box of gloves readily available since they will be changed frequently. NOTE: We use nitrile gloves for all animal handling.</li>
	<li>Cleaning test materials and cages between subjects with a disinfectant/sterilizing agent is also an important step in this battery of tests in order to reduce the potential for spreading disease as well as remove undesired olfactory cues.</li>
</ol>
2. Buried Pellet Test
<ol>
	<li>At least two days before testing, record the weight of each mouse and then food restrict to 90% of body weight. Prior to testing and during food restriction, give each mouse 1-2 pieces of the pellets to be used during the test (e.g., a piece of sweetened cereal). Do not skip this step because mice are neophobic with food and may not search for the pellet during the test if they have not eaten the pellets previously.</li>
	<li>On all test days, habituate the mice for 1 hr prior to testing by placing their cage in the testing room with no water bottle or feeder bin. House them in their home cage with just a filter top lid.</li>
	<li>During habituation, fill a clean mouse cage ~3 cm high with clean bedding making certain the bedding is evenly distributed throughout the cage. Set a timer for 5 min.</li>
	<li>Following 1 hr of habituation, bury 1 sweetened cereal pellet 0.5 cm below the bedding so that it is not visible.</li>
	<li>Remove the test mouse from its home cage, place it in the center of the test cage, place the filter top lid on the cage and start the timer.</li>
	<li>Stop the timer when the mouse uncovers the pellet and begins eating it. Note the time to uncover the buried pellet.</li>
	<li>If the mouse does not find the pellet within 5 min, end the trial and note a score of 300 sec for that mouse. Move the pellet to the top of the bedding so the mouse has access to it, and allow the mouse to eat the pellet.</li>
	<li>Following the trial, return the mouse to its home cage.</li>
	<li>Empty the bedding from the test cage and clean the cage with animal room cleaning solution.</li>
	<li>Repeat steps 2.4 to 2.9 for each mouse, and change gloves before and after each mouse.</li>
	<li>After all mice are tested, give them just enough food to maintain them at 90% body weight.</li>
	<li>Perform testing on days 2-5 the same way as test day 1 with one exception; bury the pellet in a different spot in the cage for each trial.</li>
	<li>On testing day 6, perform the surface pellet trial.</li>
	<li>For the surface pellet trial, follow the same procedure for test day 1 but instead of burying the pellet under the bedding place it on top of the bedding. Record the time for the mouse to find and start eating the pellet.</li>
</ol>
3. Block Test
<ol>
	<li>Individually house mice in clean cages and place 5 blocks in the cage (labeled A-E), changing gloves before setting up each cage.</li>
	<li>Perform the test 24 hr later. Move test mice to the testing area, remove the water bottle and feeder bin, and place all 5 blocks from the cage along with a handful of bedding into a plastic bag labeled with the animal&#8217;s identification. Place the sealed plastic bag on top of the mouse&#8217;s home cage.</li>
	<li>Habituate the animals in their home cage without the water bottle, feeder bin, and blocks for 1 hr prior to testing.</li>
	<li>Change gloves between each cage so that the scents are not exchanged between animals/blocks.</li>
	<li>Line up the mouse cages beside each other on a table with at least 10 cm between each cage. Position a video camera so that the front of the cage (not the long side of the cage) is in clear view.</li>
	<li>Set the timer for 30 sec and label a card with the important experiment details (date, mouse ID, trial, etc.). Videotape the label for 2-3 sec.</li>
	<li>Remove blocks A-D from the plastic bag with that mouse&#8217;s identification and place them in the middle of the cage so that they are clearly visible on the video camera. Make sure there is ~1 cm of space between each of the blocks. Place the filter top back on the cage. Start the timer and videotape for 30 sec.</li>
	<li>After 30 sec, stop recording and remove the blocks from the cage and place them back into the plastic bag.</li>
	<li>Change gloves and then move on to the next mouse, repeating the same procedure used for the first trial. Do this for a total of 6 trials for each mouse making sure there is an inter-trial interval of ~5 min.</li>
	<li>On the 7th trial, follow the same procedure for the trials 1-6 except instead of placing block D from the mouse&#8217;s own cage add block E from another mouse&#8217;s cage so that the mouse is exposed to blocks A, B, and C from its own home cage and block E from another mouse&#8217;s cage. Note in the lab book whose block E each mouse is exposed to and alternate where block E is placed in each mouse&#8217;s cage (e.g., ABCE or AEBC). Take block E from a mouse of the same sex but not from an original cagemate. Videotape for 30 sec.</li>
	<li>Following the 7 trials, return animals to a new clean cage with their original cagemates. Clean blocks used in the test with mild detergent and water and allow to air dry for use in later tests.</li>
</ol>
4. Habituation/Dishabituation
<ol>
	<li>Perform the habituation/dishabituation test in a similar manner to the block test but instead of using blocks that have the odor of a mouse, use tissue cartridges holding cotton scented with different pairs of extracts.</li>
	<li>Follow steps 3.1-3.4 using a single, unscented tissue cartridge instead of the blocks.</li>
	<li>Habituate mice in the test room.</li>
	<li>Prepare the scented tissue cartridges in a separate room. Place a small cotton ball into a clean cartridge and then add 5 &#956;l&#160;of extract (e.g., almond extract) into the cotton. Snap the cartridge top over the cotton and place in a dedicated box or bag labeled with that scent.</li>
	<li>Do the same procedure for a second scent (e.g., anise extract). Change gloves between handling different scents. Make sure the cotton ball is completely encased in the tissue cartridge. NOTE: Exposed fibers from the cotton ball may cause the animal to have interest in the cotton ball for nesting purposes rather than the scent itself.</li>
	<li>Then, follow steps 3.6-3.10 using one scented tissue cartridge for the first six trials, and the second scented tissue cartridge for the seventh trial.</li>
</ol>
5. Analysis of Videotapes
<ol>
	<li>For the block and habituation/dishabituation tests, have a rater blind to experimental condition measure the time spent sniffing each block, with sniffing defined as nasal contact with that block. If desired, measure other behaviors such as time to approach the novel block (E) during Trial 7 and total activity (the number of movements made along the length and width of the home cage) during each trial. Score&#160;the time spent sniffing and time to approach from the videotape using a stopwatch.</li>
	<li>Similarly, for the habituation/dishabituation test, have a rater blind to experimental condition measure the time spent sniffing the cartridge, time to approach the cartridge, and locomotor activity.</li>
</ol>
6. Statistics
<ol>
	<li>Analyze the buried pellet test using nonparametric statistics because the latency to find the pellet scores tend to show heterogeneity of variance. Average the latency to locate the pellet across days 3&#8211;5 and then compare between groups of mice using a Mann&#8211;Whitney U-test. Similarly, for the surface pellet part of the test, analyze latency to find the pellet using a Mann&#8211;Whitney U-test to compare genotypes.</li>
	<li>For the block test, analyze the data from Trial 7 (introduction of the novel-scented block). Typically, employ nonparametric analyses to account for heterogeneity of variance. In order to analyze differences in time spent sniffing the novel block as well as time to approach the blocks for different experimental groups, use the Mann&#8211;Whitney U-test. Use the Wilcoxon Signed Rank test to compare time spent sniffing the novel block to time spent sniffing the familiar blocks.</li>
	<li>For the habituation/dishabituation test, conduct parametric analyses on Trials 1, 6 and 7, similar to previous studies20. If mice exhibit little to no sniffing, use nonparametric analyses.</li>
</ol>

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We have no conflicts of interest.

Each of the tests described in this study measure different aspects of olfactory function in mice. The buried pellet test measures the food motivation aspect of olfaction, testing the ability of hungry (food restricted, not food deprived) mice to detect a palatable piece of sweetened cereal buried under bedding. The block test measures more of the social aspect of olfactory function, testing the ability of mice to discriminate between their own scent and that of a conspecific. The habituation/dishabituation test assesses the ability of the mouse to discriminate between familiar and novel, innocuous scents. Using multiple tests is important when characterizing a new model because anomalies in food motivation or fear could contribute to differences observed in mutant mice compared to controls. For example, if only the block test is performed and decreased sniffing of the block that has the odor of another mouse is observed, it is unclear whether there is an olfactory deficit or an enhanced fear response to the conspecific that may lead to avoidance of that block. When multiple tests are performed and deficits are observed in all tests, it strongly supports an interpretation of olfactory impairment. However, if differences are observed in only one test but not the others then there may be a more subtle olfactory impairment but it will be essential to rule out other explanations (i.e., enhanced fear or reduced food motivation). Additional important factors to keep in mind when testing olfactory function mice include the background strain and sex of the mice. Different genetic background strains (i.e., C57BL/6, DBA, etc.) can have profound effects on mouse behavior therefore, it is recommended to adapt each protocol in wildtype mice of the same background before performing the entire experiment. It is also recommended that male and female mice be tested separately from each other because the male olfactory system is highly sensitive to females in estrous and olfactory detection of a female in estrous could interfere with performance in all three tests.
Some steps are absolutely critical to follow when testing olfaction in mice. It is important to be cognizant of the odors the experimenter is introducing to the animals. Wearing gloves for the procedures is essential and frequent changing of gloves between animals is required. It is always a good practice for the experimenter not to wear cologne or perfume on olfaction testing days. While some parts of the procedure are inflexible, there are other parts that can be modified and adapted without reducing the validity or sensitivity of the test. For example, the number of habituation trials can be increased or decreased depending on the strain of mice being tested and how quickly they habituate to the stimuli. The major limitation of these tests is that they are all driven by some form of motivation, be it food or social, making it difficult to completely rule out anomalies in motivation as an explanation when an altered response observed. This can be minimized by analyzing additional parameters, such as activity during testing and time to approach stimuli.
Once mastered, the tests can be easily used in examining the phenotype of novel mouse models of neurodegenerative disease. In addition, the tests that have the highest power can be included in preclinical studies testing potential therapeutics (for an example see ref. 25).

Olfactory dysfunction is linked to a number of neurodegenerative disorders including Parkinson&#8217;s disease (PD), Alzheimer&#8217;s disease, and Huntington&#8217;s disease1. In PD, olfactory impairments include deficits in odor identification, detection, and discrimination and are found in up to 70&#8211;95% of patients2-5. These deficits can precede the cardinal motor symptoms of PD by up to 4 years, indicating that olfactory dysfunction may signal the early stages of PD6-10. The early occurrence of olfactory deficits in PD has led to a keen interest in olfactory dysfunction and the underlying mechanisms involved. In preclinical studies in rodents, olfactory dysfunction could be a sensitive outcome measure to predict the therapeutic potential of novel therapeutic strategies.
Many tests have been designed and extensively used to characterize sensorimotor impairments in rodent models of PD and to test the therapeutic potential of novel treatments11-15. Even though olfactory deficits are well documented in PD, olfactory function has not been routinely measured in many models. This view is changing though with the discovery of genetic forms of PD and the more accepted notion that PD is a systemic disorder affecting more than just sensorimotor function. Currently, there are numerous studies in genetic mouse models of PD and other neurodegenerative disorders that now include analysis of olfaction in the characterization16-24. Given the growing interest of olfactory dysfunction in neurodegenerative disorders, we sought to assemble a battery of olfactory tests that can be used to characterize novel models of neurodegeneration as well as test potential disease-modifying therapies in preclinical studies. The tests described in the present study have been used in both characterization and preclinical studies18,25.
The tests highlighted in this study have been shown to be sensitive in detecting olfactory dysfunction in a frequently utilized alpha-synuclein overexpressing mouse model of Parkinson&#8217;s disease18. They include the buried pellet test26,27, an adapted version of the block test23,24,28,29, and the habituation/dishabituation test30. It is important to note that there are several adaptations of the tests described in this study that are sensitive measures of olfactory function in mice, the ones highlighted in this study are the tests our laboratory has the most experience with and routinely use.

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olfactory assays for mouse models of neurodegenerative disease

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process and may be a useful behavioral marker for early detection. Earlier detection in neurodegenerative disease is a major goal in the field because this is when neuroprotective therapies have the best potential to be effective. Therefore, in preclinical studies testing novel neuroprotective strategies in rodent models of neurodegenerative disease, olfactory assessment could be highly useful in determining therapeutic potential of compounds and translation to the clinic. In the present study we describe a battery of olfactory assays that are useful in measuring olfactory function in mice. The tests presented in this study were chosen because they measure olfaction abilities in mice related to food odors, social odors, and non-social odors. These tests have proven useful in characterizing novel genetic mouse models of Parkinson&#8217;s disease as well as in testing potential disease-modifying therapies.

The buried pellet, block, and habituation/dishabituation tests are all highly advantageous evaluations of olfaction in mice. Using these tests, we have found significant changes in olfaction in multiple genetic mouse models of Parkinson&#8217;s disease, including alpha-synuclein overexpressing (Thy1-aSyn)18 and Atp13a2 knockout mice. Both Thy1-aSyn and Atp13a2 knockout mice take longer to find the buried pellet than controls18. Figures 1-3 show data collected from wildtype and Atp13a2 knockout mice. In the buried pellet test, Atp13a2 knockout mice show increased latency to find the buried pellet compared to wildtype control mice (Figure 1). In the block test both wildtype and Atp13a2 knockout mice sniff the novel block from another mouse&#8217;s cage compared to blocks from their own home cage (Figure 2). In the habituation/dishabituation test wildtype mice show habituation to one odor and then increased sniffing when a novel odor is introduced (Figure 3).
<img alt="Figure 1" fo:content-width="5in" src="/files/ftp_upload/51804/51804fig1highres.jpg" width="500" /> 
Figure 1. Buried pellet test. Latency to find the pellet in wildtype (n = 10) and Atp13a2 KO (n = 14) at 20-27 m of age. * p &#60; 0.05, Mann-Whitney U.
<img alt="Figure 2" fo:content-width="5in" src="/files/ftp_upload/51804/51804fig2highres.jpg" width="500" /> 
Figure 2. Block test. Time sniffing the novel block (E) in the block test in wildtype (n = 10) and Atp13a2 KO (n = 12) female mice at 20 - 27m of age. &#916;&#916; represents p &#60; 0.01 compared to blocks A, B, and C from the same genotype. Mann-Whitney U.
<img alt="Figure 3" fo:content-width="5in" src="/files/ftp_upload/51804/51804fig3highres.jpg" width="500" /> 
Figure 3. Habituation/dishabituation test. Mean time sniffing a scented cartridge in wildtype mice (age 9 m, n = 7) across 6 trials and the introduction of a cartridge with a novel scent on trial 7.

Watch this Scientific Journal Video about Olfactory Assays for Mouse Models of Neurodegenerative Disease at JoVE.com

Olfactory Assays for Mouse Models of Neurodegenerative Disease

Impairment in olfactory function is a common feature in many neurodegenerative disorders including Parkinson, Alzheimer, and Huntington diseases. In the present article, we describe a set of tests for assessing olfaction discrimination and detection in mice that can be used to measure olfactory abilities in mouse models of neurodegenerative diseases.

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process ...

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21.9K Views.  University of Cincinnati. Impairment in olfactory function is a common feature in many neurodegenerative disorders including Parkinson, Alzheimer, and Huntington diseases. In the present article, we describe a set of tests for assessing olfaction discrimination and detection in mice that can be used to measure olfactory abilities in mouse models of neurodegenerative diseases.

Video: Olfactory Assays for Mouse Models of Neurodegenerative Disease

Assessment of Sensorimotor Function in Mouse Models of Parkinson's Disease

Sensitive and reliable behavioral outcome measures are essential to the evaluation of potential therapeutic treatments in preclinical trials for many neurodegenerative diseases. In Parkinson's disease, sensorimotor tests sensitive to varying degrees of nigrostriatal dysfunction are fundamental for testing the efficacy of potential therapeutics. Reliable and quite elegant sensorimotor measures exist for rats, however many of these tests measure sensorimotor asymmetry within the rat and are not entirely suitable for the newer genetic mouse models of PD. We have put together a battery of sensorimotor tests inspired by the sensitive tests in rats and adapted for mice. The test battery highlighted in this study is chosen for a) its sensitivity in a wide variety of mouse models of PD, b) its ease in implementing into a study, and c) its low expense. These tests have proven useful in characterizing novel genetic mouse models of PD as well as in testing potential disease-modifying therapies.

In Parkinson's disease and movement disorders in general, sensitive and reliable behavioral assays are essential for testing novel potential therapeutics. Here, we describe a manageable battery of sensorimotor tests for mice that are sensitive to varying degrees of injury to the nigrostriatal system and useful for preclinical studies.

Sensitive and  reliable behavioral outcome measures are essential to the evaluation of  potential therapeutic treatments in preclinical trials for many  ...

Behavior

Testing for Odor Discrimination and Habituation in Mice

This video demonstrates a technique to establish the presence of a normally functioning olfactory system in a mouse. The test helps determine whether the mouse can discriminate between non-social odors and social odors, whether the mouse habituates to a repeatedly presented odor, and whether the mouse demonstrates dishabituation when presented with a novel odor. Since many social behavior tests measure the experimental animal&#8217;s response to a familiar or novel mouse, false positives can be avoided by establishing that the animals can detect and discriminate between social odors. There are similar considerations in learning tests such as fear conditioning that use odor to create a novel environment or olfactory cues as an associative stimulus. Deficits in the olfactory system would impair the ability to distinguish between contexts and to form an association with an olfactory cue during fear conditioning. 
In the odor habitation/dishabituation test, the mouse is repeatedly presented with several odors. Each odor is presented three times for two minutes. The investigator records the sniffing time directed towards the odor as the measurement of olfactory responsiveness. A typical mouse shows a decrease in response to the odor over repeated presentations (habituation). The experimenter then presents a novel odor that elicits increased sniffing towards the new odor (dishabituation). After repeated presentation of the novel odor the animal again shows habituation. This protocol involves the presentation of water, two or more non-social odors, and two social odors. In addition to reducing experimental confounds, this test can provide information on the function of the olfactory systems of new knockout, knock-in, and conditional knockout mouse lines.

This manuscript describes a protocol to examine the olfactory system of rodents. The olfactory habituation/dishabituation test will allow investigators to determine whether a mouse habituates to a repeatedly presented odor and whether the mouse demonstrates dishabituation when presented a novel odor.

This video demonstrates a technique to establish the presence of a normally functioning olfactory system in a mouse. The test helps determine whether the ...

Simple and Computer-assisted Olfactory Testing for Mice

Olfaction is highly conserved among species and is required for reproduction and survival.
In humans, olfaction is also one of the senses that is affected with aging and is a strong predictor of neurodegenerative diseases. Thus, olfaction testing is used as a non-invasive diagnostic method to detect neurological deficits early on. In order to understand the mechanisms underlying olfactory network susceptibility, olfactory research in rodents has gained momentum in the past decade.
Here, we present a very simple, time efficient and reproducible olfactory testing method of innate odor perception and sensitivity in mice without the need of any prior food or water restriction. The tests are performed in a familiar environment to the mice, require only the scents and a 2 min session of odorant exposure. The analysis is performed, post-hoc, using computer-assisted commands on ImageJ and can be, therefore, carried out from start to end by one researcher.
This protocol does not require any special hardware or setup and is indicated for any laboratory interested in testing olfactory perception and sensitivity.

We present a simple and unbiased olfactory test in mice. With this protocol olfactory discrimination, preference, avoidance and sensitivity to a novel odor as compared to water can be assessed in single behavioral sessions. This method is indicated for a single experimenter and analysis is based on computer-assisted video processing.

Olfaction is highly conserved among species and is required for reproduction and survival.
In humans, olfaction is also one of the senses that is affected ...

Olfactory Behavioral Testing in the Adult Mouse

The rodent olfactory system is of increasing interest to scientists, studied, in part, in systems biology because of its stereotyped, yet accessible circuitry. In addition, this area's unique ability to generate new neurons throughout an organism's lifetime makes it an attractive system for developmental and regenerative biologists alike. Such interest necessitates a means for a quick, yet reliable assessment of olfactory function. Many tests of olfactory ability are complex, variable or not specifically designed for mice. Also, some tests are sensitive to memory deficits as well as defects in olfactory abilities, confounding obtained results.
Here, we describe a simple battery of tests designed to identify defects in olfactory sensitivity and preference. First, an initial general health assessment allows for the identification of animals suitable for further testing. Second, mice are exposed to various dilutions of scents to ascertain whether there is a threshold difference. Third, mice are presented with various scents, both attractive and aversive, that allow for the assessment of olfactory preference. These simple studies should make the initial characterization of olfactory behavior accessible for labs of varied resources and expertise.

Fundamental, yet unique properties of the rodent olfactory system have led to its increasing study among biologists. A relatively simple assessment of its function is then also needed. Here we describe sensitive tests for the characterization of mouse olfactory sensitivity and preference.

The rodent olfactory system is of increasing interest to scientists, studied, in part, in systems biology because of its stereotyped, yet accessible ...

Biology

Assessment of Social Transmission of Food Preferences Behaviors

Olfactory recognition deficits are suggested to be able to serve as clinical marker to differentiate Alzheimer&#39;s disease (AD) subjects from healthy aging groups. For example, olfactory dysfunction in AD can present as impairment in olfactory recognition, emerging during early stages of the disease and worsening while the disease progresses. The social transmission of food preferences (STFP) task is based on a rudimentary form of communication between rodents concerning distant foods dependent on the transmission of olfactory cues. Healthy wild-type mice would prefer to eat a novel, flavored food that was previously cued by a conspecific, and this food preference would be hampered in transgenic AD mice, such as the APP/PS1 model. Indeed, a strong preference for the cued food in C57Bl6/J mice of 3 months of age was found, and this was reduced in 3 months old transgenic APP/PS1 mice. In summary, STFP task could be a powerful measure to be integrated in present subclinical detection assays of AD.

This paper presents a protocol for the investigation of social transmission of food preference in mice. The advantages and possible applications for this procedure, for instance, in detecting early changes in AD mouse models, are highlighted. To conclude, interpretation of the results in light of critical details are discussed.

Olfactory recognition deficits are suggested to be able to serve as clinical marker to differentiate Alzheimer&#39;s disease (AD) subjects from healthy ...

Assessing Olfactory Impairment in Mice Due to Inhaled Environmental Pollutants

Studying the Effects of Inhaled Environmental Pollutants on Olfactory Function in Mice

Olfactory impairment is a significant public health problem and independently predicts the risk of neurodegenerative diseases. Inhaled environmental pollutants exposure may impair olfaction; thereby, there is an urgent need for methods to evaluate the effects of inhaled environmental pollutants exposure on olfaction. Mice are ideal models for olfactory experiments because of their highly developed olfactory system and behavioral characteristics. To assess the effects of inhaled environmental pollutants exposure on olfactory function in mice, a detailed buried food test and social odor discrimination experiment is provided, including the experiment preparation, the selection and construction of experimental facilities, the testing process, and indexes of time. Meanwhile, timekeeping equipment, operational details, and the experimental environment are discussed to ensure the success of the assay. Zinc sulfate is used as the treatment to demonstrate the feasibility of the experimental approach. The protocol provides a simple and clear operational process for assessing the effects of inhaled environmental pollutants on olfactory function in mice.

Author Spotlight: Assessing the Olfactory Effects of Airborne Pollutants &#8212; Buried Food and Social Odor Tests

This paper provides a detailed description of the buried food test and social odor discrimination experiment to assess the effects of inhaled environmental pollutants exposure on olfactory function in mice.

Olfactory impairment is a significant public health problem and independently predicts the risk of neurodegenerative diseases. Inhaled environmental ...

Environment

Designing a Flexible, Cost-Effective Olfactometer for Rodent Olfactory Experiments

Constructing an Olfactometer for Rodent Olfactory Behavior Studies

The use of olfactometers to study rodent behavior and brain activity during olfactory tasks is crucial for understanding brain circuits. These sophisticated devices allow researchers to precisely control and deliver odor stimuli, enabling the investigation of complex olfactory processes in rodents. Although commercially available olfactometers are convenient, they present challenges when technical issues arise, often requiring costly assistance and potentially disrupting research timelines. This article details the construction of a custom olfactometer specifically designed for mouse olfactory behavior experiments, providing a comprehensive list of parts and step-by-step instructions. The olfactometer is controlled through MATLAB, offering a user-friendly interface for researchers. Importantly, the open-source code allows users to modify and adapt the system, tailoring behavioral tasks to meet specific experimental needs. Building a customized olfactometer empowers users with the knowledge and capability to perform custom experimental design and troubleshooting independently, saving both time and resources. This approach not only enhances research flexibility but also fosters a deeper understanding of the equipment's functionality, ultimately leading to more robust and reliable olfactory studies in rodents.

Constructing an Olfactometer for Rodent Olfactory Behavior Studies Near-Infrared Spectroscopy Hyperscanning Study in Psychological Counseling

This protocol describes the construction of an olfactometer for go/no-go olfactory behavior experiments. Step-by-step instructions, along with images, are provided to ensure the successful construction of the olfactometer. Information for troubleshooting issues encountered during the process is also included.

The use of olfactometers to study rodent behavior and brain activity during olfactory tasks is crucial for understanding brain circuits. These ...

A Free-breathing fMRI Method to Study Human Olfactory Function

The study of human olfaction is a highly complex and valuable field with applications ranging from biomedical research to clinical evaluation. Currently, evaluation of the functions of the human central olfactory system with functional magnetic resonance imaging (fMRI) is still a challenge because of several technical difficulties. There are some significant variables to take into account when considering an effective method for mapping the function of the central olfactory system using fMRI, including proper odorant selection, the interaction between odor presentation and respiration, and potential anticipation of or habituation to odorants. An event-related, respiration-triggered olfactory fMRI technique can accurately administer odorants to stimulate the olfactory system while minimizing potential interference. It can effectively capture the precise onsets of fMRI signals in the primary olfactory cortex using our data post-processing method. The technique presented here provides an efficient and practical means for generating reliable olfactory fMRI results. Such a technique can ultimately be applied in the clinical realm as a diagnostic tool for diseases associated with olfactory degeneration, including Alzheimer&#39;s and Parkinson&#39;s disease, as we begin to further understand the complexities of the human olfactory system.

We present the technical challenges and solutions for obtaining reliable functional magnetic resonance imaging (fMRI) data from the human central olfactory system. This includes special considerations in olfactory fMRI paradigm design, descriptions of fMRI data acquisition with an MRI-compatible olfactometer, odorant selection, and a special software tool for data post-processing.

The study of human olfaction is a highly complex and valuable field with applications ranging from biomedical research to clinical evaluation. Currently, ...

Assessment of Spontaneous Alternation, Novel Object Recognition and Limb Clasping in Transgenic Mouse Models of Amyloid-&#946; and Tau Neuropathology

Here we describe a staged, behavioral testing approach that can be used to screen for compounds that exhibit in vivo efficacy on cognitive and functional motor behaviors in transgenic mouse models of &#946;-amyloidosis and tauopathy. The paradigm includes tests for spontaneous alternation in a Y-maze, novel object recognition, and limb clasping. These tests were selected because they: 1) interrogate function of cognitive or motor domains and the correlate neural circuitry relevant to the human disease state, 2) have clearly defined endpoints, 3) have easily implementable quality control checks, 4) can be run in a moderate throughput format, and 5) require little intervention by the investigator. These methods are designed for investigators looking to screen compounds for activity in short-term and working memory tasks, or functional motor behaviors associated with Alzheimer's disease mouse models. The methods described here use behavioral tests that engage a number of different brain regions including hippocampus and various cortical areas. Investigators that desire cognitive tests that specifically assess cognition mediated by a single brain region could use these techniques to supplement other behavioral tests.

Described here is a staged, behavioral screening approach that can be used to screen for compounds that exhibit in vivo efficacy on cognitive and functional motor behaviors in transgenic mouse models of &#946;-amyloidosis and tauopathy. These methods are optimized to screen compounds for activity in short-term and working memory tasks.

Here we describe a staged, behavioral testing approach that can be used to screen for compounds that exhibit in vivo efficacy on cognitive and functional ...

Medicine

An Objective and Reproducible Test of Olfactory Learning and Discrimination in Mice

Olfaction is the predominant sensory modality in mice and influences many important behaviors, including foraging, predator detection, mating, and parenting. Importantly, mice can be trained to associate novel odors with specific behavioral responses to provide insight into olfactory circuit function. This protocol details the procedure for training mice on a Go/No-Go operant learning task. In this approach, mice are trained on hundreds of automated trials daily for 2&#8211;4 weeks and can then be tested on novel Go/No-Go odor pairs to assess olfactory discrimination, or be used for studies on how odor learning alters the structure or function of the olfactory circuit. Additionally, the mouse olfactory bulb (OB) features ongoing integration of adult-born neurons. Interestingly, olfactory learning increases both the survival and synaptic connections of these adult-born neurons. Therefore, this protocol can be combined with other biochemical, electrophysiological, and imaging techniques to study learning and activity-dependent factors that mediate neuronal survival and plasticity.

Here, we train mice on an associative learning task to test odor discrimination. This protocol also allows for studies on learning-induced structural changes in the brain.