The accommodation index is a

statistic A statistic (singular) or sample statistic is any quantity computed from values in a sample which is considered for a statistical purpose. Statistical purposes include estimating a population parameter, describing a sample, or evaluating a hypo ...

used in the

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, development ...

s for describing

spike train An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, c ...

data. Many methods of experimental neuroscience, such as voltage clamp recordings, give their output in the form of measured voltages of individual neurons. Generally, the only important element of these voltage traces is the occurrence of spikes in the voltage, representing

action potentials An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, c ...

. It is often useful to be able to describe the data in terms of the spike timings; for instance, when optimizing a compartmental model towards observed behaviour, statistics such as this can be used to gauge error. Various statistics are used to do this, such as spike rate, average interspike interval, and the accommodation index. It is similar to other measures of accommodation such as the local variance introduced by Shinomoto et al. in 2003. It is defined by the average of the difference in length of two consecutive interspike intervals (ISIs) normalized by the summed duration of these two ISIs. The equation for the accommodation index is

A=\frac\displaystyle\sum_^\frac

Where N is the number of APs and k determines the number of ISIs that will be disregarded in order not to take into account possible transient behavior as observed in Markram et al., 2004. A reasonable value for k is either four ISIs or one-fifth of the total number of ISIs, whichever is the smaller of the two.

References

* * *{{cite journal , last1=Markram , first1=Henry , last2=Toledo-Rodriguez , first2=Maria , last3=Wang , first3=Yun , last4=Gupta , first4=Anirudh , last5=Silberberg , first5=Gilad , last6=Wu , first6=Caizhi , title=Interneurons of the neocortical inhibitory system , journal=Nature Reviews Neuroscience , date=October 2004 , volume=5 , issue=10 , pages=793–807 , doi=10.1038/nrn1519 Metrics Neuroscience