, 1996). An integrator receiving synchronous input may appear to use a narrow window, but the window size is really a property of the neuron, not of the stimulus, which supports a neuron-centric definition of operating mode as opposed to a stimulus-centric one (Rudolph and Destexhe, 2003). The importance of a neuron-centric definition becomes clear when comparing synchrony transfer: integrators respond to synchronous input, but they do not transfer that synchrony as robustly as coincidence detectors do (see Figure 1). Before proceeding, it is worth noting that simply
Selleckchem Trametinib having a spike threshold endows the neuron with sensitivity to the derivative of the input current or membrane potential (Agüera y Arcas and Fairhall, 2003; Hong et al., 2007). In line with this, it has been shown that the simple threshold-and-fire model as well as leaky integrate-and-fire models can transfer synchrony under the appropriate stimulus conditions (Burak et al., 2009; Goedeke and Diesmann, 2008; Schultze-Kraft et al., 2013; this website Tchumatchenko et al., 2010). However, as Tchumatchenko et al. and Schultze-Kraft et al. note, this is true only for limited (and arguably unrealistic) stimulus conditions, i.e., high input synchrony driving large membrane potential fluctuations. In real neurons and in more sophisticated
Methisazone models whose spike initiation dynamics implement band-pass filtering, and which are therefore preferentially sensitive to relevant stimulus frequencies, the stimulus requirements for robust synchrony transfer are much less stringent (and more plausible). Rate coding is broadly accepted as the pre-eminent coding strategy in the brain; by comparison, synchrony coding is contentious and often considered applicable only to particular systems like the
auditory midbrain. We contend that synchrony coding occurs more broadly based on several lines of evidence. We will organize our discussion of that evidence around the 3-fold requirements for synchrony coding (Figure 3A): (1) principal neurons must have coincidence detector traits (in order to reliably transfer synchrony under realistic stimulus conditions), (2) they must receive synchronous input that contains information, and (3) they must produce synchronous output that can be decoded. Note that rate coding and synchrony coding are not mutually exclusive even though factors that facilitate one often do so at the expense of the other. The feasibility and utility of each coding strategy should be gauged independently, contrary to many past debates. Requirement 1 is satisfied insofar as principal neurons can and do operate as imperfect coincidence detectors.