Role of inhibition in the antennal lobe: gain control and odor invariance across concentrations

RAMON HUERTA; AYELEN NALLY; MARACHLIAN EMILIANO; LOCATELLI FERNANDO

San Diego

Congreso; 46th Meeting of the American Society for Neuroscience; 2016

American Society for Neuroscience

Role of inhibition in the antennal lobe:gain control and odor invariance across concentrations  Emiliano Marachlian1,2,3,Ayelen Nally1, Ramón Huerta4,Fernando Locatelli1,31.Departamento de Fisiología, Biología Molecular y Celular, FCEyN , UBA, Argentina2.Departamento de Física, FCEyN , UBA, Argentina.3. IFIByNE-CONICET, Argentina4.Biocircuits Institute, UCSD, USA. Animals need to extract informationfrom complex and noisy environments. Even though the animals form theirinternal image of the surroundings through a multisensory system, each senseneeds to be able to recognize (in some range) the identity of one stimulusregardless of its intensity and independently of complex or noisy background(if the stimulus is biologically relevant). Therefore the first processinglevel, where the sensory signal is adapted and organized, plays a fundamentalrole in sensory systems. In the olfactory system thechemical cues are detected and primarily encoded by the olfactory sensoryneurons. Each specific odor recruits a particular combination of receptors thatprovides the input for its internal representation. The great neuronalconvergence in the Antennal Lobe (approximately 60,000 olfactory sensoryneurons converge into around 800 projection neurons organized in 160 glomeruliin the honey bee) requires a signal adaptation. In insects the first processingis done by the local inhibitory neurons located in the Antennal Lobe.Nevertheless the specific form in which the signal is adapted is not fully known.In this work we investigate the action of the different GABA components andtheir role in gain control and stabilization of neural activity patternselicited by a range of odor concentrations. We use honey bees as model animaland perform calcium imaging to measure the neural representations from low tohigh odor concentrations in the projection neurons of the Antennal Lobe. Withdifferent GABA blockers we isolate and identify the specific contributions ofGABA-A and GABA-B components. We also introduce math and computational modelswith which we confirm experiment interpretations, study the networkcontribution and evaluate the robustness of this mechanism for different inputpatterns. We show that the GABAergic neuronsplay an important role, stabilizing the pattern representation and regulatinglevels of activity, allowing animals to generalize the odor identity acrossconcentrations. The simplicity of the system under study suggests thatanalogous versions could be involved in other sensory systems and even inhigher levels of processing.