However, CFs fire about once per second whether or not an event occurs, raising the question of how sensory-driven signals might be distinguished from a background of ongoing spontaneous activity.
CFs fire bursts spontaneously at ∼1 Hz (Thach, 1968), a low rate that is barely modulated during sensory stimulation (Simpson et al., 1996).
Previous work has shown that some CFs fire a burst of spikes when the unexpected periocular airpuff is delivered (Sears and Steinmetz, 1991; Nicholson and Freeman, 2003), and that this signal is sufficient for conditioning (Mauk et al., 1986; Thompson et al., 1998).
Unfortunately, the adaptive timing model can be confused by the presence of noise in CF firing because it is based on individual, and not population learning of PCs.
Notably, both of them seem to measure the relative CF firing activity compared to its two temporal averages, giving the PC a chance to habituate to the prolonged changes in CF activity.
4) In the subsection "Ontogeny of Purkinje neuron spontaneous activity patterns", the argument is weak because the reduction in EPSP frequency could be due to a reduction in CF firing rate.
The CF-PC synapse is one of the most powerful and reliable in the brain (Schmolesky et al., 2002; Ohtsuki et al., 2009): each time the CF fires a burst, it evokes in PCs both a burst of sodium spikes in the soma known as a complex spike (Eccles et al., 1966; Thach, 1968), and a massive calcium-based spike in the dendrite (Llinás and Sugimori, 1980).
We have shown that the amplitude of sensory-driven calcium events in a PC dendrite is graded and provides analog information about stimulus strength in single trials, that is more dendritic calcium if CF input fires in response to a strong periocular airpuff, less calcium for weak airpuffs.
Cf. Gerard Baker, Britain Fires a Shot Heard Round the World, Wall St. J., June 25 , 2016 at A1 (describing the referendum result as a political earthquake for the United Kingdom); Steven Erlanger, Cameron to Quit as E.U.
First, they occurred spontaneously at about 1 Hz (0.4 1.4 Hz; median 0.7 Hz; Figure 1C), which is similar to the characteristic spontaneous firing rate of CFs reported previously in awake animals (Thach, 1968).
Control units tested with cooling or MDP did not differ in characteristic frequency (CF), FRA area or firing rate.
