TY - JOUR
T1 - Spontaneous activity does not predict morphological type in cerebellar interneurons
AU - Haar, Shlomi
AU - Givon-Mayo, Ronit
AU - Barmack, Neal H.
AU - Yakhnitsa, Vadim
AU - Donchin, Opher
N1 - Publisher Copyright:
©2015 the authors.
PY - 2015/1/28
Y1 - 2015/1/28
N2 - The effort to determine morphological and anatomically defined neuronal characteristics from extracellularly recorded physiological signatures has been attempted with varying success in different brain areas. Recent studies have attempted such classification of cerebellar interneurons (CINs) based on statistical measures of spontaneous activity. Previously, such efforts in different brain areas have used supervised clustering methods based on standard parameterizations of spontaneous interspike interval (ISI) histograms. We worried that this might bias researchers toward positive identification results and decided to take a different approach.Werecorded CINs from anesthetized cats. We used unsupervised clustering methods applied to a nonparametric representation of the ISI histograms to identify groups of CINs with similar spontaneous activity and then asked how these groups map onto different cell types. Our approach was a fuzzy C-means clustering algorithm applied to the Kullbach–Leibler distances between ISI histograms. We found that there is, in fact, a natural clustering of the spontaneous activity of CINs into six groups but that there was no relationship between this clustering and the standard morphologically defined cell types. These results proved robust when generalization was tested to completely new datasets, including datasets recorded under different anesthesia conditions and in different laboratories and different species (rats). Our results suggest the importance of an unsupervised approach in categorizing neurons according to their extracellular activity. Indeed, a reexamination of such categorization efforts throughout the brain may be necessary. One important open question is that of functional differences of our six spontaneously defined clusters during actual behavior.
AB - The effort to determine morphological and anatomically defined neuronal characteristics from extracellularly recorded physiological signatures has been attempted with varying success in different brain areas. Recent studies have attempted such classification of cerebellar interneurons (CINs) based on statistical measures of spontaneous activity. Previously, such efforts in different brain areas have used supervised clustering methods based on standard parameterizations of spontaneous interspike interval (ISI) histograms. We worried that this might bias researchers toward positive identification results and decided to take a different approach.Werecorded CINs from anesthetized cats. We used unsupervised clustering methods applied to a nonparametric representation of the ISI histograms to identify groups of CINs with similar spontaneous activity and then asked how these groups map onto different cell types. Our approach was a fuzzy C-means clustering algorithm applied to the Kullbach–Leibler distances between ISI histograms. We found that there is, in fact, a natural clustering of the spontaneous activity of CINs into six groups but that there was no relationship between this clustering and the standard morphologically defined cell types. These results proved robust when generalization was tested to completely new datasets, including datasets recorded under different anesthesia conditions and in different laboratories and different species (rats). Our results suggest the importance of an unsupervised approach in categorizing neurons according to their extracellular activity. Indeed, a reexamination of such categorization efforts throughout the brain may be necessary. One important open question is that of functional differences of our six spontaneously defined clusters during actual behavior.
KW - Cerebellar cortex interneurons
KW - Fuzzy C-means clustering
KW - Inter-spike interval
UR - http://www.scopus.com/inward/record.url?scp=84921931982&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84921931982&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.5019-13.2015
DO - 10.1523/JNEUROSCI.5019-13.2015
M3 - Article
C2 - 25632121
AN - SCOPUS:84921931982
SN - 0270-6474
VL - 35
SP - 1432
EP - 1442
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 4
ER -