The CTHs are expressed in terms of percent of peak discharge frequency (Fn), since the emphasis is on the contour of the discharge pattern rather than absolute discharge frequency (amplitude). Timing pulses triggered at the upstroke and post-peak downstroke of the phrenic neurogram were used to create cycle-triggered histograms (CTHs) with 50 or 100 ms bins. The spikes were sorted using Cambridge Electronic Design (CED) Spike2, version 7 software. The electrodes were linearly arranged with an inter-electrode spacing of 100 µm. Extracellular spike activity was recorded from the PB-KF region using a 16-electrode NeuroNexus probe. The data were recorded from vagotomized dogs ventilated with an air-O2 mixture and maintained in hyperoxic isocapnia (F IO2>0.6, end-tidal CO 2 range 40-50 mmHg).
The discharge patterns of 135 PRG neurons obtained from recordings in a decerebrated dog model (n=12 preparations) were used to develop a method to automatically classify discharge patterns according to their contours. In general, clustering involves grouping data into categories based on some measure of inherent similarity or distance. 2010) and it is implemented via SigmaPlot User-Defined transform scripts (SigmaPlot 11.0, Systat Software, Inc. It is based on the K-means clustering technique ( Aravind et al. The purpose of this report is to present a method that automatically classifies neurons according to their discharge patterns and derives an average subgroup contour of each class. Due to the variety of patterns, it can be difficult to classify them into distinct subgroups according to their discharge contours. Also found in this region are non-respiratory related (NRM) neurons, which show tonic activity patterns ( Segers et al. The neuronal activities of these pontine respiratory group (PRG) neurons exhibit a variety of discharge patterns, including inspiratory (I), expiratory (E) and phase spanning patterns ( Segers et al.
2004 Cohen 1971 Dutschmann and Dick 2012 Prkic et al. Respiratory-related neurons in the parabrachial-Kölliker-Fuse (PB-KF) region of the pons play a key role in the control of phase timing and breathing frequency ( Alheid et al. Analysis of the results suggests that the k-means clustering method offers a robust objective means of both automatically categorizing neuron patterns and establishing the underlying archetypical contours of subtypes based on the discharge patterns of group of neurons.
Additional methods for choosing the optimal number of clusters are described. The discharge patterns of 135 canine PRG neurons were classified into 7 distinct subgroups. It is based on the K-means clustering technique and it is implemented via SigmaPlot User-Defined transform scripts. This report presents a method that automatically classifies neurons according to their discharge patterns and derives an average subgroup contour of each class. The neuronal activities of these pontine respiratory group (PRG) neurons exhibit a variety of inspiratory (I), expiratory (E), phase spanning and non-respiratory related (NRM) discharge patterns. Respiratory-related neurons in the parabrachial-Kölliker-Fuse (PB-KF) region of the pons play a key role in the control of breathing.