Abstract
Many neurons possess dendrites enriched with sodium channels and are capable of generating action potentials. However, the role of dendritic sodium spikes remain unclear. Here, we study computational models of neurons to investigate the functional effects of dendritic spikes. In agreement with previous studies, we found that point neurons or neurons with passive dendrites increase their somatic firing rate in response to the correlation of synaptic bombardment for a wide range of input conditions, i.e. input firing rates, synaptic conductances, or refractory periods. However, neurons with active dendrites show the opposite behavior: for a wide range of conditions the firing rate decreases as a function of correlation. We found this property in three types of models of dendritic excitability: a Hodgkin-Huxley model of dendritic spikes, a model with integrate and fire dendrites, and a discrete-state dendritic model. We conclude that fast dendritic spikes confer much broader computational properties to neurons, sometimes opposite to that of point neurons.
Highlights
Increasing evidence shows that nonlinear integration of synaptic inputs in dendrites is crucial for the computational properties of neurons
Calcium imaging allowed for the direct observation of calcium spikes (Jaffe et al 1992; Miyakawa et al 1992; Regehr et al 1989; Regehr and Tank 1990; 1992), while glutamate uncaging and voltage sensitive dyes led to the discovery of NMDA spikes (Schiller et al 2000; Polsky et al 2004)
We investigate the impact of the refractory period duration on inverse processing using a multi-compartment integrate and fire model. We show that this phenomenon is present in simplified discrete-state dendritic models
Summary
Increasing evidence shows that nonlinear integration of synaptic inputs in dendrites is crucial for the computational properties of neurons. A major role in the integration is played by dendritic spikes: regenerative currents through Na+, Ca2+ or NMDAr channels. Dendritic spikes allow for more subtle integration of synaptic input than in a passive dendrite. A single dendritic branch can act as a coincidence detector, generating a spike when exposed to synchronized input (Williams and Stuart 2002; Losonczy and Magee 2006; Polsky et al 2004). After the initiation of a dendritic spike, sodium channels inactivate and the branch switches into a refractory state which crucially affects integration (Remy et al 2009). Backpropagating action potentials play an essential role in spike time-dependent plasticity (Magee et al 1997; Bi and Poo 1998; Markram et al 1997), and the participation of local dendritic spikes has been implicated in long-term potentiation (Golding et al 2002; Kim et al 2015)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
