Hangyalab had it’s first FENS poster in Copenhagen!

Bursting cholinergic neurons of the basal forebrain show synchronous activity in an auditory detection task

Tamás Laszlovszky 1
1Institute of Experimental Medicine of the Hungarian Academy of Sciences, Department of Cellular and Network Neurobiology Lendület Laboratory of Systems Neuroscience, Budapest, Hungary
Tamás Laszlovszky 2
2Pázmány Péter Catholic University, Faculty of Information Technology and Bionics, Budapest, Hungary
Adam Kepecs 3
3Cold Spring Harbor Laboratory, Neuroscience Program, Cold Spring Harbor, USA
Balazs Hangya 4
4Institute of Experimental Medicine of the Hungarian Academy of Sciences, Department of Cellular and Network Neurobiology Lendület Laboratory of Systems Neuroscience, Budapest, Hungary
The cholinergic basal forebrain (CBF) has been implicated in diverse cognitive functions through its influence on cortical information processing. Earlier studies differentiated tonic and phasic effects of the CBF based on the varying timescales of cortical acetylcholine release (Parikh et al., 2007). In accordance, in vitro experiments described an early- and a late firing cholinergic group, likely corresponding to bursting and non-bursting neurons (Unal et al., 2012), proposing that bursting neurons convey phasic information while non-bursting neurons set tonic levels of cortical acetylcholine. However, this theory has not been tested in vivo, therefore it remains unclear how bursting and non-bursting groups of CBF contribute to cholinergic effects at different time scales (Hangya et al., 2015).

To address this question we analyzed optogenetically identified and putative CBF neurons (n = 44) in mice performing an auditory detection task requiring sustained attention. Our analysis of autocorrelations (Royer et al., 2012) uncovered three types of cholinergic neurons: ‘tonic’ neurons showing long refractory periods, ‘phasic bursting’ neurons showing classical bursting phenotype and ‘phasic non-bursting’ neurons exhibiting short refractory but no prominent burst shoulders. By analyzing cross-correlations of concurrently recorded pairs of neurons (n = 16) we discovered that the bursting ones were synchronously active at a short timescale, unlike the tonically active cholinergic neurons. However, all three cell types were capable of fast and precise responses to behaviorally salient events. Thus, bursts of cholinergic neurons likely reflect strong bottom-up excitatory drive that, with the added synchrony, leads to stronger and more wide-spread cortical activation.