| Comments |
p.764 right column 2nd paragraph:"As an example of the energetic cost of information transmission through synapses, if [investigators] set typical physiological values of s = 0.01 (implying a firing rate of S = 4 Hz) and p = 0.25, Equation 3 states that, out of the 32 bits/s arriving at the synapse, 6.8 bits/s are transmitted, and from the estimate by Attwell and Laughlin (2001) of the underlying synaptic energy cost (Evesicle = 1.64 × 10^5 ATP molecules per vesicle released BNID 108667), this is achieved at a cost of S·p·Evesicle = 1.64 × 10^5 ATP/s. Thus, information transmission typically costs ~24,000 ATP per bit, similar to the estimate of Laughlin et al. (1998). Increasing the release probability to 1 leads to an information transmission rate of 32 bits/s, at a cost of 20,500 ATP/bit." p.763 left column bottom paragraph:"If the mean spike firing rate is S, the probability of an action potential arriving in any given interval is s = S?t (with 0 < s < 1)." p.763 right column bottom paragraph:"For a synapse with a single release site (e.g., to the orange cell
in Figure 3), if each time a presynaptic action potential arrives
a vesicle is released with probability p, then for p < 1 information
is lost during synaptic transmission." |