Biophysical mechanisms and computational principles of weak signal detection.

• Applicant: Dr. Sarah Nicola Jung
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2013 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 237638727

The nature of the neural code is one of the fundamental questions in neuroscience. Understanding the neural code for sensory systems requires both specifying a map between external signals and the resulting spike trains and demonstrating that downstream neural circuits can interpret or decode this mapping and therefore direct behavioral output. By combining electrophysiology, modeling and pharmacology I want to understand explicitly on a cellular level how decoding of a temporal neural code is performed by downstream neurons. Weak signal detection in pyramidal cells (PC) of weakly electric fish is an excellent model to study this question. Neuroanatomical work has thoroughly described the network connectivity of the electrosensory circuits. The input neurons (primary afferents) to PCs have been investigated electrophysiologically and modeled in great detail. Using a relatively simple model system (e.g. as compared to mammalian cortex) will enable me to link cellular coding mechanisms to a specific sensory task, e.g. amplification of weak signals. The project will consist of three major elements: 1) determining the neuronal code of PCs for weak signals using extracellular recordings; 2) using these data to develop a model of the cellular dynamics that transforms the primary afferent code into the PC code; 3) using the model to make strong predictions as to the cellular basis of decoding and testing these predictions by intracellular recordings and pharmacological manipulations. Since the cellular basis of PC synaptic input amplification (e.g. AMPA, NMDA and GABA receptors plus various voltage-gated ion channels) is found in all mammalian sensory systems, the decoding algorithm I will develop should be generally applicable and neuroscientists working on other systems will be able to evaluate whether it is realized by the synaptic dynamics in the visual, auditory or somatosensory system.

• DFG Programme: Research Fellowships
• International Connection: Canada
• Hosts: Professor Andre Longtin, Ph.D.; Professor Leonard Maler, Ph.D.