After eclosion, adult flies (5-7 days old) were transferred into the T-maze part of a designed T maze (MazeEngineers™) and allowed to habituate for 60 s.
Maze Engineers, the maker named in the paper, is part of ConductScience.
Train groups of fruit flies to avoid an odor paired with electric shock, then test what they learned, and how long they remember it, at the T-maze choice point. Labs use the test to study the genes and brain circuits behind memory.
How It Works
Training happens in a tube lined with a copper grid. A vacuum pump draws the first odor from its odor cup through the tube. At the same time, the shock controller, run from a PC, shocks the flies through the grid. A second odor follows without shock.
An elevator in the T-maze then moves the flies to the choice point, where both odors arrive and the flies pick a side. You count the flies in each choice tube. You set the airflow with the pump's knob and read it on the flow meter.
Add-ons and modifications
Add-on
Price
Details
Complete system
$4,900
T-maze choice area, copper-grid training tube, shock controller and software, vacuum pump with airflow knob and flow meter, odor cups, tubing and clamp
T maze Choice Area only
$1,499
T-maze choice area, odor cups, vacuum and tubing, clamp
Light Dark T maze Choice
$1,599
T-maze choice area with a manual light switch for one chamber, odor cups, vacuum and tubing, clamp
Add any of these to your quote request.
Maze Type
binary T-maze
Training tube
Copper shock grid on the inner surface
Grid Material
copper
Tube size
2 cm inner diameter, 9 cm long
Odor delivery
Vacuum pump with airflow knob and flow meter
Odor cups
For liquid odors
Shock control
Shock controller and software, run from a PC
Behavioral Construct
associative learning
aversive conditioning
olfactory discrimination
memory formation
classical conditioning
shock avoidance learning
Automation Level
semi-automated
Material
copper
Perspex
Species
Drosophila
Research Domain
Aging Research
Behavioral Genetics
Behavioral Neuroscience
Behavioral Pharmacology
Learning and Memory
Neurodegeneration
Compatible Tracking Software
ConductVision
Shipping weight
25.0 lb
Shipping box
L: 43.18 cm
W: 43.18 cm
H: 27.94 cm
Behavioral Genetics
Test how gene mutations change learning and each phase of memory.
Behavioral Neuroscience
Pair the test with genetic tools that switch neurons on or off to map memory circuits.
Aging Research
Measure age-related memory decline. Memory 1 h after training is the usual measure, because it appears especially vulnerable to aging (Malik and Hodge 2014).
Neurodegeneration
Test how fly models of neurodegenerative disease change memory.
Behavioral Pharmacology
Test how drug treatments, diet and sleep change memory.
Practical Tips
Shock
Check with a voltmeter that the grid delivers 60 V.
Grids
Check and clean the copper grids regularly, and replace any that have oxidized.
Seals
Check the tube fittings regularly for an airtight seal.
Odor cups
After experiments, wash the odor cups with hot water and odorless detergent, let them dry, and coat each with 10 µl Sigmacote.
Tubes
Now and then, clean the Perspex tubes with hot water and odorless detergent.
What’s in the Box
T-maze with elevator and choice point
Training tube with copper shock grid
Shock controller and software
Vacuum pump
Odor cups
Tubing
Clamp
Warranty
ConductScience provides a standard 1-year manufacturer warranty covering defects in materials and workmanship, with technical support for protocol optimization and troubleshooting.
Haiko Poppinga, Rotem Mika, Maria Schwartz et al. · Biology Open · 2026
From the methods
After eclosion, adult flies (5-7 days old) were transferred into the T-maze part of a designed T maze (MazeEngineers™) and allowed to habituate for 60 s.
Laura Tamberg, Carl Sander Kiir, Jürgen Tuvikene et al. · eNeuro · 2026
From the methods
...paper previously soaked with deionized water and dried. The vial was attached to a T-maze (Maze Engineers) and left to rest while air flow was applied for 30 s. Then, first odor presented.
Quinn, Harris and Benzer showed in 1974 that fruit flies learn to avoid an odor paired with electric shock, and that the memory lasts 24 h 1. Labs have used odor conditioning since then to study the genetics of memory 4.
Tully and Quinn turned the test into a classical (Pavlovian) design in 1985. Flies received twelve shock pulses during the first odor and none during the second, then chose between the two odors at a T-maze choice point. In their experiments, 95% of trained flies typically avoided the shock-paired odor 2.
Flies with mutations in amnesiac, rutabaga or dunce show appreciable learning, but their memory fades quickly over the first 30 min 2. In mushroom body neurons, one particular adenylyl cyclase combines the odor and shock signals 5.
§ 2
Methods
2.1 Procedure
Steps and timings from Malik and Hodge (2014).
Pre-test setup
1.Collect flies: Collect flies 1 to 2 days before the test and sort them into groups of about 25 under mild CO₂.
2.Dilute the odors: Dilute 4-methylcyclohexanol 1:67 and 3-octanol 1:100 in mineral oil. Ethyl acetate and isoamyl acetate are other common odors.
3.Fill the odor cups: Pipette 30 µl of each diluted odor into its own odor cup.
Trial sequence
1.Adapt: Load a group into the training tube and let the flies adapt to the tube and airflow for 90 s.3
2.First odor with shock: Present the first odor with 60 V shock, given as twelve 1.25 s pulses with 3.75 s between pulses, for 60 s in total.3
3.Second odor: Rest for 30 s with no odor or shock, then present the second odor for 60 s without shock.3
4.Choice test: Move the flies to the T-maze choice point and give them 120 s to choose between the two odors.3
5.Count and reverse: Count the flies in each choice tube. Then train a reciprocal group, with the shock paired to the other odor.3
Critical methodological constraints
Reciprocal groups. With one group alone, a preference for one odor cannot be told apart from learning. Averaging reciprocal groups, one with each odor shock-paired, cancels that preference.34
Red light only. Flies cannot see dim red light, so they choose by smell. Run training and testing under a red LED.3
Balanced odors. Set the dilutions so untrained flies split about evenly between the two odors, and check this each day. A clear preference before training weakens the score after training.34
2.2 Measurement & Analysis
Score memory with the performance index, and run two controls that rule out a smell or shock problem.
Performance index
Learning or memory score
Flies that avoided the shock-paired odor, minus flies that chose it, divided by the flies in both choice tubes. The two reciprocal groups are averaged into one index.3
Retention
Score after a delay
The performance index measured after a delay. The discussion below lists the memory phase each delay measures.3
Odor acuity
Sensory control
Untrained flies choose between one odor and air for 2 min. Avoiding the odor shows they can smell it.3
Shock reactivity
Sensory control
Flies choose between a tube with 60 V shock and one without for 2 min. Escaping the shock shows they can feel it.3
+ Record for each group: genotype, age, odor dilutions, shock voltage and the delay between training and test.
2.3 Percent avoiding the shock-paired odor
Enter the counts from one group. The note below turns the same counts into a performance index.
Inline calculator
Type the values your tracker recorded.
Avoided
80.0%
With 80 flies avoiding and 20 choosing the shock-paired odor, the performance index is (80 − 20) / (80 + 20) = 0.6 3. Average it with the reciprocal group's index to score the experiment.
§ 3
Results
3.1 Sample apparatus output
Tube counts from one experiment: two groups, each trained with a different shock-paired odor.
Illustrative counts that Malik and Hodge (2014) use to show the calculation. The experiment's performance index is the mean of the two groups: (0.6 + 0.5) / 2 = 0.55.
§ 4
Discussion
Limitations of the paradigm, methodological caveats, and current directions.
4.1 Common confounds
Variables that can shift Drosophila Olfactory Conditioning results apart from the effect under study.
Smell and shock sensing
A line that cannot smell the odors or feel the shock scores low even if its memory works, so run the odor acuity and shock reactivity controls alongside memory tests.3
Genetic background
Malik and Hodge outcross mutant and transgenic lines to a wild-type strain for at least six generations to control for genetic background.3
Room humidity
Okray et al. call humidity crucial for shock training: keep the room at or above 55%, with about 70% optimal.4
Shock and odor strength
Avoidance rises with shock intensity and odor concentration. Hold both constant across the groups you compare.2
4.2 Construct validity caveats
Each test delay reads a different memory phase. Testing right after training measures learning; 30 min or 1 h gives short-term memory, and 3 h gives mid-term memory 3. Spaced training builds long-term memory that needs CREB-dependent transcription and can last a week, while massed training builds anesthesia-resistant memory 3. After one training session, wild-type memory declines over about seven hours but is still present at 24 h 2.
4.3 Special considerations
How many flies go in one training group?
It varies by lab: about 25 flies in Malik and Hodge 3, about 100 in Okray et al. 4 and about 150 in the original Tully and Quinn design 2. Okray et al. add that most published olfactory memory data use at least 8 performance indices for each genotype or condition, each from 200 flies 4.
How is long-term memory tested?
Give 5 training cycles 15 min apart (spaced). Massed training, the same 5 cycles back to back, builds anesthesia-resistant memory instead. Keep the flies at 18 °C and 70% humidity in the dark, move them to 25 °C at least 1 h before testing, and test 24 h after training 3.
What does a performance index of 0 mean?
The flies split evenly between the two odors and showed no memory 4. By the Malik and Hodge formula, 1 means every fly avoided the shock-paired odor 3. Okray et al. subtract the other way, so their perfect score is −1 4.
Okray et al. (2025) note that memory studies have moved from single genes to the neural circuits behind memory, while the T-maze test has changed little.
Emerging
Color and odor together
A recent protocol pairs color cues with odors to study multisensory learning (Okray et al. 2025).
§ 5
Background references
5 selected methods and validation studies of the Drosophila Olfactory Conditioning, from any lab.
Quinn WG, Harris WA, Benzer S. Conditioned behavior in Drosophila melanogaster. Proc Natl Acad Sci U S A. 1974;71(3):708-712.PMID:4207071
Tully T, Quinn WG. Classical conditioning and retention in normal and mutant Drosophila melanogaster. J Comp Physiol A. 1985;157(2):263-277.doi:10.1007/BF01350033
Malik BR, Hodge JJL.Drosophila adult olfactory shock learning. J Vis Exp. 2014;(90):e50107.doi:10.3791/50107
Okray Z, Jacob PF, Moszynski JP, Talbot CB, Waddell S. Classical conditioning of adult Drosophila. Cold Spring Harb Protoc. 2025;2025(8):pdb.prot108566.doi:10.1101/pdb.prot108566
Busto GU, Cervantes-Sandoval I, Davis RL. Olfactory learning in Drosophila. Physiology (Bethesda). 2010;25(6):338-346.doi:10.1152/physiol.00026.2010
