Temperature Effects on Neuronal Network Activity
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1
RIKEN , Quantitative Biology Center, Germany
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2
ETH Zurich, Department of Biosystems Science and Engineering, Switzerland
Motivation
Hibernation enables animals to survive winter food shortage by reducing their metabolism. During torpor, profound hypothermia suppresses electrical brain activity, which leads to a sleep deficit (Daan et al., 1991). Torpor also triggers Tau-protein-phosphorylation-associated spine regression as it occurs in the event of Alzheimer's disease. Both effects of hypothermia are reversible upon arousal and do not impair memory (Bullmann et al., 2015). We studied cultured neurons in vitro, which exhibit synchronized bursts (SBs) reminiscent of sleep (Hinard et al., 2012). Furthermore, we measured axonal delays and connectivity in order to simulate the temperature dependence of the SBs (Izhikevich, 2006).
Material and Methods
Dissociated neurons from E16-18 rat neocortex were cultured at low density on high-density microelectrode arrays (HDMEAs, Frey et al., 2010). After identification of the axon initial segments, network activity was recorded, and action potentials were tracked along complete axonal arbors of single neurons at subcellular resolution. Recordings were performed over a wide temperature range (10~35°C) within 4~16 hours. Morphological and functional connectivity was quantified by axonal delay τAxon and time lag between spike trains τISI, as described elsewhere (Huber et al., 2016).
Results
Axonal delays, period and length of SBs as well as inter spike interval showed different temperature dependencies. Morphological and functional connections overlapped and the axonal delay τAxon correlated with the time lag τISI. Functional connectivity was affected by cooling. SBs were observed over a wide temperature range with significant changes in their temporal structure, which was reversible upon rewarming suggesting persistence of network memories during cooling.
Discussion
Next, we will investigate the role of axonal delays by incorporation the network structure and temperature dependence of axonal conduction into neuronal network simulations.
Conclusion
Temperature plays a fundamental role in physiology and medicine and HDMEAs are very suitable to study temperature effects on neuronal characteristics in vitro.
References
Bullmann, T., Seeger, G., Stieler, J., Hanics, J., Reimann, K., Kretzschmann, T.P., Hilbrich, I., Holzer, M., Alpár, A., Arendt T. 2016. Tau phosphorylation-associated spine regression does not impair hippocampal-dependent memory in hibernating golden hamsters. Hippocampus. 26(3): 301-18.
Daan, S., Barnes, B.M., Strijkstra, A.M. 1991. Warming up for sleep? Ground squirrels sleep during arousals from hibernation. Neuroscience Letters 128(2): 265-268.
Frey, U., Heer, F., Pedron, R., Ballini, M., Müller, J., Bakkum, D., Hafizović, S, Faraci, F.D., Greve, F. Kirstein, K.-U., Hierlemann, A. 2010. Switch-matrix-based high-density microelectrode array in CMOS technology. IEEE Journal of Solid-State Circuits 45(2): 467?482.
Hinard, V., Mikhail, C., Pradervand, S., Curie, T., Houtkooper, R.H., Auwerx, J., Franken, P., Tafti, M. 2012. Key electrophysiological, molecular, and metabolic signatures of sleep and wakefulness revealed in primary cortical cultures. The Journal of Neuroscience 32(36): 12506-12517.
Huber, S., Bullmann, T., Deligkaris, K., Hierlemann, A., Frey, U. 2016. Assessment of Connectivity in Neuronal Cultures by Recording from Axonal Arbors. 10th international Meeting on Substrate-integrated Microelectrode Arrays, Reutlingen, Germany
Izhikevich, E.M. 2006. Polychronization: computation with spikes. Neural computation 18(2): 245?82.
Figure
Changes in synchronized bursting are fully reversible upon rewarming.
Rasterplot of spike for neuron number vs. time showing bursts at different temperatures during cooling (upper row) and subsequent rewarming (lower row). Network decorrelation is measured by the SPIKE distance.
Keywords:
temperature,
Axonal delay,
Synchronized bursts,
polychronous groups
Conference:
MEA Meeting 2016 |
10th International Meeting on Substrate-Integrated Electrode Arrays, Reutlingen, Germany, 28 Jun - 1 Jul, 2016.
Presentation Type:
Poster Presentation
Topic:
MEA Meeting 2016
Citation:
Bullmann
T,
Huber
S,
Deligkaris
K,
Hierlemann
A and
Frey
U
(2016). Temperature Effects on Neuronal Network Activity.
Front. Neurosci.
Conference Abstract:
MEA Meeting 2016 |
10th International Meeting on Substrate-Integrated Electrode Arrays.
doi: 10.3389/conf.fnins.2016.93.00096
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Received:
22 Jun 2016;
Published Online:
24 Jun 2016.
*
Correspondence:
Dr. Urs Frey, RIKEN, Quantitative Biology Center, Kobe, Germany, urs.frey@mxwbio.com