Szyszka P, Galizia CG (2018)
The Role of the Sucrose-Responsive IR60b Neuron for Drosophila melanogaster: A Hypothesis
Chemical senses 43 (5), 311-312

We share an alternative hypothesis to a recently published one, about how IR60b may be a gatekeeper for the fly crop and for predigestion, rather than for obesity control.

Lüdke A, Raiser G, Nehrkorn J, Galizia CG, Herz AVM, Szyszka P (2018)
Calcium in Kenyon Cell Somata as a Substrate for an Olfactory Sensory Memory in Drosophila
Frontiers in cellular neuroscience 12, 128

In a tour-de-force along the olfactory path, we show how olfactory information is represented in receptor neuron axon terminals, in projection neuron dendrites, in projection neuron somata, in kenyon cell dendrites and kenyon cell somata. We show that, based on calcium concentration, only the kenyon cell somata may form a substrate for a still elusive form of memory: trace sensory memory.

Egea-Weiss A, Renner A, Kleineidam CJ, Szyszka P (2018)
High Precision of Spike Timing across Olfactory Receptor Neurons Allows Rapid Odor Coding in Drosophila
iScience 4, 76-83

We show that odor-evoked spikes in olfactory receptor neurons show an unexpected precision in terms of response time. As a consequence, response time may be used to increased odorant sensitivity by at least two orders of magnitude!

Sehdev A, Mohammed YG, Triphan T, Szyszka P (2018)
Olfactory object recognition based on fine-scale stimulus timing in Drosophila
IScience 2019, 13:113-124. doi: 10.1016/j.isci.2019.02.014

A behavioral study in the fruit fly Drosophila shows that temporal disparities as short as 5 ms allow the fly to segragate two odorants, irrespective of whether their valence is innately different, or learned.

Biergans SD, Galizia CG, Reinhard J, Claudianos C (2015)
Dnmts and Tet target memory-associated genes after appetitive olfactory training in honey bees
Sci.Rep. 5.

Olfactory memory is mediated by methylation and de-methylation of specific genes in the honeybee brain. There is a Corrigendum in Sci.Rep. 6:21656 because two figures were inverted.

Schubert M, Sandoz JC, Galizia CG, Giurfa M (2015)
Odourant dominance in olfactory mixture processing: what makes a strong odourant?
Proc Biol Sci 282:(1892).

An analysis of how odor components contribute to an odor mixture's percept.

Wehmann HN, Gustav D, Kirkerud NH, Galizia CG (2015)
The sound and the fury - bees hiss when expecting danger.
PLoS ONE 10(3):e0118708.

In an aversive training protocol on freely moving bees, running away is not the only response: they also hiss, a finding that expands the known behavioral repertoire, and allows for additional readout functions.

Afify A, Galizia CG (2015)
Chemosensory Cues for Mosquito Oviposition Site Selection. 
J. Med. Entomol. 1–11, DOI: 10.1093/jme/tju024

A review about all chemicals so far published that influence oviposition site selection.

Shen M, Szyszka P, Deussen O, Galizia CG Merhof D (2015)
Automated tracking and analysis of behavior in restrained insects.
J Neurosci Methods 239C:194-205. doi: 10.1016

We developed a new software to track the movement of antennae and mandibles in restrained bees, allowing for quantitative and graded behavioral readouts in classical conditioning experiments.

Shen M, Huang W, Szyszka P, Galizia CG, Merhof D (2014)
Interactive Framework for Insect Tracking with Active Learning.
IEEE International Conference on Pattern Recognition (ICPR), pp. 2733-2738, Aug. 24-28, 2014, Stockholm, Sweden. (oral presentation)

Szyszka P, Gerkin RC, Galizia CG, Smith BH (2014)
High-speed odor transduction and pulse tracking by insect olfactory receptor neurons.
Proc Natl Acad Sci U S A 111: doi: 10.1073/pnas.1412051111

We demonstrate that odor transduction in insect can be as fast as 1.6ms, and pulses can be tracked way over 100 Hz, showing that olfaction is a fast sense in insects.

Galizia CG (2014)
Olfactory coding in the insect brain: data and conjectures.
Eur J Neurosci : pp 1-12 / doi: 10.1111/ejn.12558

A review about the neural networks in the insect olfactory system, explaining the functional role of the different kind of synapses and cells that are known, in the antennal lobe, the mushroom bodies and the lateral protocerebrum. Learning and Memory are localized in all of these networks, but for different purposes and with different properties.

Lüdke A, Galizia CG (2014)
Sniffing cancer: Will the fruit fly beat the dog?
ChemoSense 15(4):3-15

A review about how animals can be used to detect cancer smell, and how recently fruit flies were added to the list of animals that could be used for this purpose.

Ignatious Raja JS, Katanayeva N, Katanaev VL, Galizia CG (2014)
Role of Go/i subgroup of G proteins in olfactory signaling of Drosophila melanogaster.
European J. Neurosci pp 1-11 DOI: 10.1111/ejn.12481.

We find that G_o/i contributes to the odor response in Drosophila melanogaster OR22a receptor neurons, adding to another transduction cascade, which may be ionotropic. Odor transduction thus appears to be a complex cascade with many players working in parallel.

Strauch M, Lüdke A, Münch D, Laudes T, Galizia CG, Martinelli E, Lavra L, Paolesse R, Ulivieri A, Catini A, Capuano R, Di Natale C (2014)
More than Apples and Oranges - Detecting Cancer with a Fruit Fly’s Antenna.
Scientific Reports 4: 3576 1-9. DOI: 10.1038/srep03576

We show that fruit fly odor receptors can be used to differentiate between cells from cancer patients and cells from healthy patients.

Strauch M, Müthing C, Broeg MP, Szyszka P, Münch D, Laudes T, Deussen O, Galizia CG, Merhof D (2013)
The looks of an odour - Visualising neural odour response patterns in real time.
BMC Bioinformatics 2013, 14(Suppl 19):S6 

Fast processing of imaging data with a direct data stream will allow for future interactive experiments combining imaging and behavioral manipulations.

Meyer A, Galizia CG, Nawrot MP (2013)
Local interneurons and projection neurons in the antennal lobe from a spiking point of view.
J Neurophysiol 110: 2465-2474 DOI: 10.1152/jn.00260.2013

We identify five characteristic features in single cell recordings that allow for separating functional groups of neurons, in particular local and projection neurons in the honeybee antennal lobe.

Okle O, Rath L, Galizia CG, Dietrich DR (2013)
The cyanobacterial neurotoxin beta-N-methylamino-l-alanine (BMAA) induces neuronal and behavioral changes in honeybees.
Toxicol Appl Pharmacol 270: 9-15. doi: 10.1016/j.taap.2013.04.003.

We find that the neurotoxin BMAA affects learning and memory in honeybees, it also affects odor processing, and generates reactive oxigen species. The results suggest that honeybees can be used as model animals to study BMAA action, a toxin that in humans leads to neurodegenerative diseases.

Burger H, Ayasse M, Doetterl, Kreissl S, Galizia CG (2013)
Perception of floral volatiles involved in host-plant finding behaviour: comparison of a bee specialist and generalist.
J Comp Physiol 199: 751-761

We show that the antennal lobes of Andrena vaga, a bee species that collects pollen only from Salix (willows), are particularly sensitive to 1,4-dimethoxybenzene, a behaviour-mediating odorant of host flowers.

Kirkerud NH, Wehmann HN, Galizia CG, Gustav D (2013)
APIS - a novel approach for conditioning honey bees
Front Behav Neurosci 7:29. doi: 10.3389/fnbeh.2013.00029.

We develop a new tool to study honeybee learning, with an automated approach and aversive conditioning. The tool is adaptable to other insects too.

Shen M, Szyszka P, Galizia CG, Merhof D (2013)
Automatic framework for tracking honeybee's antennae and mouthparts from low framerate video
IEEE International Conference on Image Processing (ICIP) 2013, Sept. 15-18, Melbourne, Australia.

We develop a framework to analyze behavioral responses in PER training in a quantitative manner, using automatic image analysis.

Nowotny T, Stierle J, Galizia CG, Szyszka P (2013)
Data-driven honeybee antennal lobe model suggests how stimulus-onset asynchrony can aid odour segregation
Brain Res 1536: 119-134.  DOI: dx.doi.org/10.1016/j.brainres.2013.05.038

We construct a computational model of the antennal lobe in honeybees, and show that this network can enhance elemental odor information when the odors are not sinchronous in an odour mixture.

Rein J, Mustard JA, Strauch M, Smith BH, Galizia CG (2013)
Octopamine modulates activity of neural networks in the honey bee antennal lobe,
J Comp Physiol.A 199: 947-962. DOI: 10.1007/s00359-013-0805-y

We show that the neuromodulator octopamine affects network activity in the antennal lobe in an experience dependent way, and propose a synaptic circuit model for its action on local neurons.

Stierle JS, Galizia CG, Szyszka P (2013)
Millisecond stimulus onset-asynchrony enhances information about components in an odor mixture.
J Neurosci 33: 6060-6069

We show that an asynchrony of 6 ms between the components of an odor mixture is sufficient to increase information about the odor component, as measured in neurophysiological calcium responses in olfactory projection neurons.

Locatelli FF, Villareal F, Mezzinoglu K, Huerta R, Galizia CG, Smith BH (2013)
Nonassociative plasticity alters competitive interactions among mixture components in early olfactory processing.
Europ J Neurosci 37:63-79. doi: 10.1111/ejn.12021. epub 2012

We show that in an odor mixture the representation of a component is dependent on the previous exposure to this component. We use a computational model of the AL to understand the synapses involved in this plasticity.

Strauch M, Rein J, Lutz C, Galizia CG (2013)
Signal extraction from movies of honeybee brain activity by convex analysis: The ImageBee plugin for KNIME,
extended journal version, BMC Bioinformatics 14: (Suppl 18):S4

We propose an open-source tool to the neuroscience community for analyzing optical imaging data from honeybees.

Girardin CC, Kreissl S, Galizia CG (2013)
Inhibitory connections in the honeybee antennal lobe are spatially patchy.
J Neurophyiol 109:332-343. Epub 2012 Oct. 24.

We combine calcium imaging with focalized neurotransmitter application to map inhibitory connections in the antennal lobe network. We find that these connections are patchy, and different among individuals, suggesting that they derive from learning experiences.

Münch D, Schmeichel B, Silbering AF, Galizia CG (2013).
Weaker ligands can dominate an odor blend due to syntopic interactions.
Chem Senses. doi: 10.1093/chemse/bjs138

Using a detailed analysis of mixture interactions across concentrations we show how mixtures are preceived - e.g. which component of a banana-odor blend is the dominant one in perception, even though not being the  dominant one in concentration.

Strauch M, Ditzen M, Galizia CG (2012)
Keeping their distance? Odor response patterns along the concentration range.
Front Syst Neurosci 6:71. doi: 10.3389 / fnsys.2012.00071. Epub 2012 Oct 18.

We analyze odor-concentration coding and generalization across similar odorants based on calcium imaging data of olfactory projection neurons, and show that with increasing concentration more information is coded in the antennal lobe network.

Strauch M, Broeg MP, Müthing C, Szyszka P, Deussen O, Galizia, CG, Merhof D (2012)
INCIDE the brain of a bee: Visualising honeybee brain activity in real time by semantic segmentation.
Proceedings of BioVis 2012, Seattle (USA)
(download preprint)

Using fastPCA we extract olfactory glomeruli on-line during measurements, in real time, preparing the ground for future close-loop experiments.

Biergans SD, Jones JC, Treiber N, Galizia CG, Szyszka P (2012)
DNA Methylation Mediates the Discriminatory Power of Associative Long-Term Memory in Honeybees.
PLoS ONE 7(6): e39349. doi: 10.1371/journal.pone.0039349. Epub 2012 Jun 18.

We show that DNA methilation is not involved in the associative component of long term memory in bees, but it is involved in the odor-coding memory component that prevents the animals from generalizing to different odors

Strauch M, Galizia CG (2012)
Fast PCA for processing calcium-imaging data from the brain of Drosophila melanogaster
BMC Med Inform Decis Mak 2012, 12(Suppl 1):S2, doi: 10.1186/1472-6947-12-S1-S2

Invited follow-up paper

Silbering AF, Bell R, Galizia CG, Benton R (2012)
Calcium Imaging of Odor-evoked Responses in the Drosophila Antennal Lobe.
J Vis Exp 61: pii: 2976. doi: 10.3791/2976 Video

A methods paper in video format about our technique to record antennal lobe calcium imaging data.

Galizia CG, Franke T, Menzel R, Sandoz JC (2012)
Optical imaging of concealed brain activity using a gold mirror in honeybees.
J Insect Physiol 58: 743-749

By introducing a gold-sputtered cover-slip we succeeded in measuring areas of the brain that otherwhise would be inaccessible, in particular olfactory glomeruli. We can show that for the odors that we use both the frontal as well as the lateral glomeruli participate in the code.

Szyszka P, Stierle JS, Biergans S, Galizia CG (2012)
The Speed of Smell: Odor-Object Segregation within Milliseconds.
PLoS ONE, 7: e36096. doi:10.1371/journal.pone.0036096. Epub 2012 Apr 27

We show that 6 ms onset difference of two odors are sufficient for the animal to extract the information of single components in an odor mixture, with important implication for the speed of odor-information processing in the brain.

Strauch M, Rein J, Galizia CG (2012)
Signal extraction from movies of honeybee brain activity by convex analysis.
Proceedings of ICCABS, Las Vegas (USA), IEEE, 2012

A new procedure to extract glomerular areas from optical imaging data.

Girardin CC, Galizia, CG (2012)
The "Where" and "Who" in Brain Science: Probing Brain Networks with Local Perturbations.
Cogn Comput 4: 63-70

A conceptional paper about the implication that combinatorial coding has on our thinking of what it means to localize a particular function in the brain. 

Meyer A, Galizia CG (2012)
Elemental and configural olfactory coding by antennal lobe neurons of the honeybee (Apis mellifera).
J Comp Physiol A 198:159-171

Single cell analysis of odor-mixture coding in the honeybee antennal lobe, showing that depending on the mixture some cells have elemental, others configural mixture coding properties. This was one of the ten most frequently cited papers in 2013 of the published articles 2011-12 in this journal.

Proske JH, Wittmann M, Galizia CG (2012)
Olfactory sensor processing in neural networks: lessons from modeling the fruit fly antennal lobe.
Front Neuroeng 5: 2 . doi: 10.3389/fneng.2012.00002. Epub 2012 Feb 8

Modeling the antennal lobe in a computational approach using linear algebra we show that stochastic lateral inhibitory connections perform, on average, equally well as networks based on odor similarity.

Strauch M, Galizia CG (2011) A
Fast PCA for Processing Calcium-imaging Data from the Brain of Drosophila Melanogaster.
Proceedings of DTMBIO'11, ISBN: 978-1-4503-0717-8, pp. 3-10, ACM, 2011 

A new computational technique to analyze optical imaging data on-line while the experiment is being done will allow for interactive imaging experiments.

Münch D, Galizia CG (2011)
DoOR: The Database of Odorant Responses.
Chemo Sense 13: 2-6

We created a meta-database, open to the community, to collect, combine, and research odor-response profiles of olfactory receptors. The servece has been received enthusiastically by the community.

Rath L, Galizia CG, Szyszka P (2011)
Multiple memory traces after associative learning in the honey bee antennal lobe.
Eur J Neurosci 34: 352-360

We show that following associative olfactory learning, activity patterns in the antennal lobe change, and explain the changes quantitatively with two separate synaptic mechanisms, one at the orn-ln synapse, one at the orn-pn synapse.

Galili D, Lüdke A, Galizia CG, Szyszka P, Tanimoto H (2011)
Olfactory trace conditioning in Drosophila. 
J. Neuroscience 31:7240-7248 

We analyze trace conditioning in Drosophila, including its neurophysiological implementation.

Szyszka P, Demmler C, Oemisch M, Sommer L, Biergans S, Birnbach B, Silbering AF, Galizia CG (2011)
Mind the gap: olfactory trace conditioning in honeybees.
J Neurosci 31: 7229-7239

We analyze trace conditioning in great detail, showing among others that the trace is plastic (i.e. can be extended), and that it is active already with single trial conditioning.

Lehmann M, Gustav D, Galizia CG (2011)
The early bee catches the flower - circadian rhythmicity influences learning performance in honey bees, Apis mellifera.
Behavioral Ecology and Sociobiology 65: 205-215

We show that learn better in the morning – even if they expect food in the afternoon.

Najar-Rodriguez AJ, Galizia CG, Stierle J, Dorn S (2011)
Behavioral and neurophysiological responses of an insect to changing ratios of constituents in host plant-derived volatile mixtures. (vol 213, pg 3388, 2010)
J Exp Biol 214: 162

Here, we show how complex interactions in the antennal lobe affect odor mixture processing, and relate this to behavioral selectivity for particular component ratios in odor mixtures. The corrigendum addresses a typo.

Beyeler M, Stefanini F, Proske H, Galizia CG, Chicca E (2010)
Exploring olfactory sensory networks: simulations and hardware emulation.
IEEE Transactions on Biomedical Circuits and Systems 270 - 273

Using biomorph chips we emulate the network in the antennal lobe in a hardware implementation, and compare it to a simplified computational model.

Galizia CG, Münch D, Strauch M, Nissler A, Ma S (2010)
Integrating heterogeneous odor response data into a common response model: A DoOR to the complete olfactome.
Chemical Senses 35: 551-563

We generate an open-access database for all known odor-response spectra in drosophila, introducing a new technique that is able to combine data from different labs. The database is a service to the community, available at https://neuro.uni-konstanz.de/door.

Kreissl S, Strasser Chr, Galizia CG (2010)
Allatostatin-immunoreactivity in the honeybee brain.
Journal of Comparative Neurology 518: 1391 - 1417

We characterize a peptidergic system in the honeybee brain from an anatomical point of view. We find that allatostatin positive neurons play a diverse role, with morphologically distinct neuron groups, in different brain areas.

Galizia CG, Rössler W (2010)
Parallel Olfactory Systems in Insects: Anatomy and Function.
Annu Rev Entomol 55: 399-420

Most insects have at least two parallel information streams in the olfactory system. This is particularly pronounced in hymenopterans. In this review, we collect what is known about the anatomy of parallel systems and analyze the putative role that they may play.

Guerrieri FJ, Nehring V, Jørgensen CG, Nielsen J, Galizia CG, d'Ettorre P (2009)
Ants recognize foes and not friends
Proc Biol Sci 276: 2461-2468

Ants protect their nest by analysing body odors of intruders. Here we show that they do not perform a simple odor-similarity computation, nor that they have distinct key-odors to recognize their nestmates (such as an "odor-passport"). Rather, they only recognize non-nestmates based on additionally present cuticular odors. Thus, there is no nestmate recognition, but only a non-nestmate recognition at a hive entrance.

Silbering AF, Okada R, Ito K, Galizia CG (2008).
Olfactory information processing in the Drosophila antennal lobe: anything goes?
J. Neurosci. 28:13075-13087.

We recorded from 5 disjunct, genetically defined cell populations (receptor neurons, 3 local neurons, projection neurons) in the antennal lobe, and showed that the transfer function can be linear, sharpening, broadening or complex, in an odor and glomerulus specific manner.

Strauch M, Galizia CG (2008)
Registration to a neuroanatomical reference atlas - identifying glomeruli in optical recordings of the honeybee brain.
Lecture Notes in Informatics, P-136, pp 85-95 (2008) 2:3.

A major advance in data-analysis technology: we developed a computational pipeline that is able to recognize glomeruli in optical imaging data, and also to register with reference to the 3D digital atlas.

Szyszka P, Galkin A, Menzel R (2008)
Associative and non-associative plasticity in Kenyon cells of the honeybee mushroom body.
Front. Syst. Neurosci. 2:3.

This is the first paper from the group where I am not a coauthor, though a part of this research was done in my group in Konstanz. Olfactory memory traces in the mushroom bodies are revealed using optical recording of selectively stained neural populations.

Piñero J, Galizia CG, Dorn S (2008)
Synergistic behavioural responses of female moths to synthetic host-plant derived mixtures are mirrored by odour-evoked calcium activity in their antennal lobes
J. Ins. Physiol. 54:333-343.

Here, we exported our expertise to applied entomology: moths use specific odorant mixtures for host finding, and we found glomeruli in the moth antennal lobe that were mixture specific and thus could be part of the physiological basis for this very specific behavior.

Galizia CG, Szyszka P (2008)
Olfactory coding in the insect brain: molecular receptive ranges, spatial and temporal coding.
Entomologia Experimentalis et Applicata 128: 81-92.

Review

Silbering A, Galizia CG (2007)
Processing of odor mixtures in the Drosophila antennal lobe reveals both global inhibition and glomerulus specific interactions
J. Neurosci. 44:11966-11977.

We recorded combinatorial odor responses in the input (receptor neurons) and output (projection neurons) of the fruit fly antennal lobe. Using odor mixtures, we revealed inhibitory and excitatory interactions across glomeruli, and present the first functional connectivity map in this structure.

Galizia CG (2007)
Brainwashing, honeybee style.
Science 317:326-327.

Sachse S, Peele P, Silbering AF, Guhmann M, Galizia CG (2006)
Role of histamine as a putative inhibitory transmitter in the honeybee antennal lobe.
Front Zool. 3:22.

This is the first study that addresses multiple inhibitory populations in the antennal lobe network. Here, we show that not only GABA, but also histamine has an inhibitory effect in the honeybee antennal lobe.

Kim YJ, Zitnan D, Galizia CG, Cho KH, Adams ME (2006)
A command chemical triggers an innate behavior by sequential activation of multiple peptidergic ensembles.
Curr Biol. 16:1395-1407.

Here, we recorded individual cells in Drosophila during development, and analyzed the role of peptides in generating motor patterns for ecdysis control.

Peele P, Ditzen M, Menzel R, Galizia CG (2006)
Appetitive odor learning does not change olfactory coding in a subpopulation of honeybee antennal lobe neurons.
J Comp Physiol A 192:1083-103.

How plastic are odor responses? In a comprehensive series of combined behavioral and physiological experiments, we show that odor-coding is stable in lACT projection neurons during 15 minutes after appetitive learning.

Pelz D, Roeske T, Syed Z, de Bruyne M, Galizia CG (2006)
The molecular receptive range of an olfactory receptor in vivo (Drosophila melanogaster Or22a).
J. Neurobiology 66:1544-1563.

In our first step towards the entire olfactome, we developed a new recording technique for odor-responses in receptor cells in intact animals, and combined this with a novel stimulation technology that allows to record hundreds of odors in an automated fashion. As a result, we could record complete dose-response curves for over 100 substances for a genetically defined odor-receptor cell class.

Vetter RS, Sage AE, Justus KA, Cardé RT, Galizia CG (2006)
Temporal integrity of an airborne odor stimulus is greatly affected by physical aspects of the odor delivery system
Chem. Senses 31:359-69.

Stimulus control is key in sensory physiology, and particularly difficult in olfaction. We developed a new technique to monitor the temporal properties of an odor stimulus. We show that even in controlled conditions, turbulences are likely to generate complex temporal patterns which will, in turn, influence physiological odor responses.

Galán RF, Weidert M, Menzel R, Herz AVM, Galizia CG (2006)
Sensory memory for odors is encoded in spontaneous correlated activity between olfactory glomeruli.
Neural Comput. 18:10-25.

We found a hitherto unknown dynamical memory trace in the antennal lobe: a single odor exposure influences patterns of spontaneous activity across projection neurons for at least two minutes after stimulation.

Szyszka P, Ditzen M, Galkin A, Galizia CG, Menzel R (2005)
Sparsening and temporal sharpening of olfactory representations in the honeybee mushroom bodies.
J Neurophysiol. 94:3303-3313.

In a further technological breakthrough, we succeeded in measuring projection neurons in the antennal lobe and in their target area, the mushroom bodies, and also measured their targets, the Kenyon cells. We show that odor representation is increasingly sharper, both as a combinatorial pattern and in its temporal structure.

Menzel R, Galizia G, Müller D, Szyszka P (2005)
Odor coding in projection neurons of the honeybee brain.
Chem. Senses 30 Suppl. 1:i301-i302.

Review

Galizia CG, J Kunze, Gumbert A, Borg-Karlson A-K, Sachse S, Markl Chr, Menzel R (2005)
Relationship of visual and olfactory signal parameters in a food-deceptive flower mimicry system.
Behav. Ecol. 16:159-168.

Here, we took an ecological approach, analyzing the responses to natural odors. We show that food-deceptive orchids use visual mimicry, but not olfactory mimicry.

Linster C, Sachse S, Galizia CG (2005)
Computational modeling suggests that response properties rather than spatial position determine connectivity between olfactory glomeruli.
J. Neurophysiol. 93:3410-3417.

Using a computational approach, we analyzed the difference in odor representation in the input and the output of the antennal lobe. We show that inhibitory interaction among glomeruli is strongest between glomeruli that are functionally similar, and not between spatial neighbors.

Skiri HT, Galizia CG, Mustaparta H (2004)
Representation of primary plant odorants in the antennal lobe of the moth Heliothis virescens using calcium imaging.
Chem. Senses 29:253-267.

Odorant receptor responses were previously known from electrophysiological measurements. Here we followed these responses into the antennal lobe using calcium imaging.

Galan RF, S Sachse, Galizia CG, Herz AVM (2004)
Odor-driven attractor dynamics in the antennal lobe allow for simple and rapid olfactory pattern classification.
Neural Comp. 16:999-1012.

A computational analysis of odor responses shows that a support vector machine would be a perfect pattern classifier. The insect mushroom bodies could implement such a support vector machine.

Galizia CG, Kimmerle B (2004)
Physiological and morphological characterization of honeybee olfactory neurons combining electrophysiology, calcium imaging and confocal microscopy.
J.Comp.Physiol.A 190:21-38.

Here, individual neurons were recorded electrophysiologically, and than imaged using calcium sensitive dyes, thus merging information about fast, electrical activity and intracellular, spatial calcium concentration.

Ditzen M, Evers JF, Galizia CG (2003)
Odor similarity does not influence the time needed for odor processing.
Chem. Senses 28:781-789.

Here, we show that in bees difficult olfactory tasks do not lead to longer behavioral delays. The result has important implication for our understanding of temporal odor-response components

Sachse S, Galizia CG (2003)
The coding of odour-intensity in the honeybee antennal lobe: local computation optimizes odour representation.
Europ. J. Neurosci. 18:2119-2139.

Another technological breakthrough: we simultaneously measured two neuron populations, the projection neurons (backfills), and a compound signal related to receptor neurons (bath application). The comparison reveals the logic of antennal lobe computation in odor-concentration coding.

Sandoz JC, Galizia CG, Menzel R (2003)
Side-specific olfactory conditioning leads to more specific odor representation between sides but not within sides in the honeybee antennal lobes.
Neuroscience 120:1137-148.

In a within-animal balanced design, we could show that learning affects glomerular responses in the antennal lobe after 24 hours.

Fiala A, Spall T, Diegelmann S, Eisermann B, Sachse S, Devaud J-M, Buchner E, Galizia CG (2002)
Genetically expressed cameleon in Drosophila melanogaster is used to visualize olfactory information in projection neurons.
Current Biology 12:1877-1884.

This is the first study ever to optically record neurons in the brain of Drosophila melanogaster. The field has boomed ever since, including two landmark papers from other groups being published later in 2002 and early 2003.

Malun D, Giurfa M, Galizia CG, Plath N, Brandt R, Gerber B, Eisermann B (2002)
Hydroxyurea-induced partial mushroom body ablation does not affect acquisition and retention of olfactory differential conditioning in honeybees
Jounal of Neurobiology 53:343-360.

In a manipulative study, we showed that learning is not affected by removing large parts of the mushroom bodies, and olfactory odor responses remain spatially invariant despite this lesion.

Sachse S, Galizia CG (2002)
The role of inhibition for temporal and spatial odor representation in olfactory output neurons: a calcium imaging study.
Journal of Neurophysiology 87:1106-1117.

Here, we succeeded in selectively recording a homogeneous population of neurons: the projection neurons. This is a step toward the cellular dissection of olfactory networks. We also used pharmacology to understand the role of local GABAergic circuits.

Carlsson MA, Galizia CG, Hansson BS (2002)
Spatial representation of odors in the antennal lobe of the moth Spodoptera littoralis (Lepidoptera: Noctuidae).
Chemical Senses 27:231-244..

In collaboration with Bill Hansson's group, we ported in vivo optical imaging to insects other than bees. Today, this technique is being used in many groups around the world.

Berg BG, Galizia CG, Brandt R, Mustaparta H (2002)
Digital atlases of the antennal lobe in two species of tobacco budworm moths, the Oriental Helicoverpa assulta (male) and the American Heliothis virescens (male and female).  
J. Comp. Neurol. 446:123-134.

As in bees, we need digital atlases for the glomerulus identity of other insects too. In collaboration with the University Trondheim we published the first atlas for two moth species. Again, this atlas is downloadable in the internet.

Laska M, Galizia CG (2001)
Enantioselectivity of odor perception in honeybees.
Behavioral Neuroscience 115:632-639.

A behavioral study showing that bees can differentiate the odors of some, but not all enantiomeres.

Galizia CG, Menzel R (2001)
The role of glomeruli in the neural representation of odors: results from optical recording studies.
Journal of Insect Physiology 47:115-129.

Review

Stetter M, Greve H, Galizia CG, Obermayer K (2001)
Analysis of calcium imaging signals from the honeybee brain by nonlinear models.
Neuroimage 13:119-128.

A computational approach showed that our calcium imaging data contains two dynamically distinct components that can be isolated mathematically.

Galizia CG, Sachse S, Mustaparta H (2000)
Calcium responses to pheromones and plant odors in the antennal lobe of the male and female moth Heliothis virescens.
Journal of Comparative Physiology A 186:1049-1063.

The macroglomerular system in moths was the main reference system for olfaction in insects at the time. Our findings validated the proposed functions of its constituent glomeruli.

Galizia CG, Menzel R (2000)
Odor perception in honeybees: coding information in glomerular patterns.
Current Opinion in Neurobiology 10:504-510.

Review

Galizia CG, Menzel R (2000).
(commentary) Probing the olfactory code.
Nature Neuroscience 3:853-854.

Galizia CG, Küttner A, Joerges J, Menzel R (2000)
Odor representation in honeybee olfactory glomeruli shows slow temporal dynamics: an optical recording study using a voltage sensitive dye.
Journal of Insect Physiology 46:877-886.

Using voltage sensitive dyes, we analyzed how the spacial code evolves in the temporal domain (we only measured slow dynamics for technical reasons).

Sachse S, Rappert A, Galizia CG (1999)
The spatial representation of chemical structures in the antennal lobe of honeybees: steps towards the olfactory code.
European Journal of Neuroscience 11:3970-3982.

Here, we then showed that chemically similar odors indeed evoke similar physiological response profiles, and that the location of glomeruli is not random.

Galizia CG, Menzel R, Hölldobler B (1999)
Optical imaging of odour-evoked glomerular activity patterns in the antennal lobes of the ant Camponotus rufipes.
Naturwissenschaften 86:533-537.

In order to have a comparative approach, we ported the technology to other species. Ants are particularly interesting because of their rich repertoire of intraspecific olfactory communication.

Laska M, Galizia CG, Giurfa M, Menzel R (1999)
Olfactory discrimination ability and odor structure-activity relationships in honeybees.
Chemical Senses 24(4):429-38.

Next, the question was whether chemically similar odors are also perceptually similar. The answer is: yes, as shown in a behavioral study.

Galizia CG, Sachse S, Rappert A, Menzel R (1999)
The glomerular code for odor representation is species specific in the honeybee Apis mellifera.
Nature Neuroscience 2:473-478.

Using the digital atlas, we could show that within the species, it is always the same glomeruli that are activated: the odor-response of identified glomeruli is genetically encoded. Thus, we created the functional atlas of the antennal lobe.

Galizia CG, McIlwrath S, Menzel R (1999)
A digital three-dimensional atlas of the honeybee antennal lobe based on optical sections acquired using confocal microscopy.
Cell Tissue Research 295:383-394.

For inter-individual comparison, we needed identified glomeruli. Thus we pioneered the creation of digital atlases that can be used as reference for glomerulus identification. The atlas is freely available: https://neuro.uni-konstanz.de/honeybeealatlas.

Galizia CG, Nägler K, Hölldobler B, Menzel R (1998)
Odour coding is bilaterally symmetrical in the antennal lobes of honeybees (Apis mellifera).
European Journal of Neuroscience 10:2964-2974.

Here, we started the question of nature/nurture in the olfactory spatial map, by first showing that the two brain halves have the same spatial code.

Galizia CG, Joerges J, Küttner A, Faber T, Menzel R (1997)
A semi-in-vivo preparation for optical recording of the insect brain.
Journal of Neuroscience Methods 76:61-69.

We published the new techniques in detail, including measurements with voltage sensitive dyes.

Joerges J, Küttner A, Galizia CG, Menzel R (1997)
Representations of odours and odour mixtures visualized in the honeybee brain.
Nature 387:285-288

In this paper, we pioneered optical imaging in insects and in the olfactory system, physiologically demonstating the combinatorial nature of olfactory coding.