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This Article Full Text Full Text (PDF) Supplemental data Supplemental data All Versions of this Article: 574/1/195    most recent jphysiol.2006.108480v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sasaki, T. Articles by Ikegaya, Y. Search for Related Content PubMed PubMed Citation Articles by Sasaki, T. Articles by Ikegaya, Y. Related Collections Neuroscience

¹ Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan

The brain operates through a coordinated interplay of numerous neurons, yet little is known about the collective behaviour of individual neurons embedded in a huge network. We used large-scale optical recordings to address synaptic integration in hundreds of neurons. In hippocampal slice cultures bolus-loaded with Ca²⁺ fluorophores, we stimulated the Schaffer collaterals and monitored the aggregate presynaptic activity from the stratum radiatum and individual postsynaptic spikes from the CA1 stratum pyramidale. Single neurons responded to varying synaptic inputs with unreliable spikes, but at the population level, the networks stably output a linear sum of synaptic inputs. Nonetheless, the network activity, even though given constant stimuli, varied from trial to trial. This variation emerged through time-varying recruitment of different neuron subsets, which were shaped by correlated background noise. We also mapped the input-frequency preference in spiking activity and found that the majority of CA1 neurons fired in response to a limited range of presynaptic firing rates (20–40 Hz), acting like a band-pass filter, although a few neurons had high pass-like or low pass-like characteristics. This frequency selectivity depended on phasic inhibitory transmission. Thus, our imaging approach enables the linking of single-cell behaviours to their communal dynamics, and we discovered that, even in a relatively simple CA1 circuit, neurons could be engaged in concordant information processing.

(Received 27 February 2006; accepted after revision 7 April 2006; first published online 13 April 2006)
Corresponding author Y. Ikegaya: Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan. Email: ikegaya{at}mol.f.u-tokyo.ac.jp

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