Simultaneous Long-term Recordings at Two Neuronal Processing Stages in Behaving Honeybees

Abstract

In both mammals and insects neuronal information is processed in different higher and lower order brain centers. These centers are coupled via convergent and divergent anatomical connections including feed forward and feedback wiring. Furthermore, information of the same origin is partially sent via parallel pathways to different and sometimes into the same brain areas. To understand the evolutionary benefits as well as the computational advantages of these wiring strategies and especially their temporal dependencies on each other, it is necessary to have simultaneous access to single neurons of different tracts or neuropiles in the same preparation at high temporal resolution. Here we concentrate on honeybees by demonstrating a unique extracellular long term access to record multi unit activity at two subsequent neuropiles 1 , the antennal lobe (AL), the first olfactory processing stage and the mushroom body (MB), a higher order integration center involved in learning and memory formation, or two parallel neuronal tracts 2 connecting the AL with the MB. The latter was chosen as an example and will be described in full. In the supporting video the construction and permanent insertion of flexible multi channel wire electrodes is demonstrated. Pairwise differential amplification of the micro wire electrode channels drastically reduces the noise and verifies that the source of the signal is closely related to the position of the electrode tip. The mechanical flexibility of the used wire electrodes allows stable invasive long term recordings over many hours up to days, which is a clear advantage compared to conventional extra and intracellular in vivo recording techniques.

Extracting the Behaviorally Relevant Stimulus: Unique Neural Representation of Farnesol, a Component of the Recruitment Pheromone of Bombus terrestris

“…The extracellular electrode consisted of three micro wires (polyurethane-coated copper wire, 14 μm in diameter, Electrisola, Escholzmatt, Switzerland). Detailed instructions of electrode building and visualization of the recording position are described in detail elsewhere [ 49 ]. A silver wire with a diameter of 25 μm (Nilaco, Tokyo, Japan) was used as reference electrode and inserted into one compound eye.…”

Analysis of Synaptic Microcircuits in the Mushroom Bodies of the Honeybee

“…The combination of behavioral manipulations, neuroanatomical circuit analyses and neurophysiology is particularly promising. The refinement of long-term multi-unit recording techniques has been an important step in this direction [105] and has led to simultaneous recordings of groups of neurons at multiple sites (neuropils) within the brain [106][107][108]. Multi-unit recordings over long time periods offer the advantage of analyzing functional consequences of structural synaptic plasticity in MB microcircuits.…”

It takes two—coincidence coding within the dual olfactory pathway of the honeybee

“…Tetrodes to record from the olfactory tracts were inserted outside the AL where l- and m-tract run in separate loops to the MB. Following electrode placement the brain was either covered with two component low viscosity silicone (Kwik-Sil, WPI, USA) or left untreated (Brill et al, 2014 ).…”

“…Electrodes consisted of three micro-wires made of copper (polyurethane-coated, 15 μm diameter, Elektrisola, Germany) and glued together with melted dental wax (Brill et al, 2014 ). One of these electrode shanks was placed to record from the l-, a second from the m-ALT, both of which were connected to a switchable headstage (SH16, Tucker-Davis-Technologies, USA).…”