PMID- 2299377
OWN - NLM
STAT- MEDLINE
DCOM- 19900306
LR  - 20171213
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 63
IP  - 1
DP  - 1990 Jan
TI  - Characteristics of background and evoked discharges of multireceptive neurons in 
      lumbar spinal cord of cat.
PG  - 1-15
AB  - 1. Intracellular recordings were made in laminae III-V of the dorsal horn of the 
      cat spinal cord from a group of multireceptive neurons that exhibited similar 
      physiological properties. The background discharge contained irregular and 
      occasional clusters of action potentials, each arising from a complex excitatory 
      postsynaptic potential (EPSP); brushing elicited more frequent clusters 
      containing more action potentials, whereas noxious heating elicited more regular 
      firing, with action potentials arising singly. The distribution of interspike 
      intervals (ISIs) was measured for the background and heat-evoked discharges and 
      revealed characteristic differences in pattern between the two states. 2. 
      Statistical tests were applied to the point process of times of occurrence of 
      spikes within a discharge to establish stationary, to identify renewal instants, 
      and to describe the process between renewal instants. In each case, the 
      statistical description of the discharge was related to the physiological state 
      of the neuron as revealed by recording of synaptic potentials and analysis of the 
      different activating inputs. 3. Background discharge was stationary, and spikes 
      occurred singly or occasionally in clusters. The data were therefore analyzed as 
      a series of "bursts," where a burst could be made up of one or more spikes. 
      Examination of the pattern of serial dependence led to the conclusion that the 
      point process renewed itself after each burst. This, together with the 
      distribution of the intervals between bursts, suggested that bursts were 
      triggered by single, distinct events, which occurred randomly at a slightly and 
      randomly varying average rate. The variation in the number of spikes in a burst 
      suggested random variation in the strength of the physiological trigger. 4. 
      Clusters of action potentials arising from a complex EPSP could be produced by 
      simultaneous stimulation of a number of fast-conducting A beta fibers in the 
      periphery and gentle mechanical stimulation, whereas stimulation of slow C fibers 
      and noxious heat evoked discrete EPSPs from which action potentials arose singly. 
      It was, therefore, concluded that background activity was, at least in part, the 
      result of random activity in a randomly varying number of A beta primary afferent 
      fibers, which could arise from operative procedures. 5. The discharge evoked by 
      heat was stationary, and the absence of serial dependence established that the 
      point process renewed itself after every spike and was, therefore, a simple 
      renewal process. The distribution of the ISIs suggested that each spike was 
      triggered by a randomly occurring physiological event.(ABSTRACT TRUNCATED AT 400 
      WORDS)
FAU - Steedman, W M
AU  - Steedman WM
AD  - Department of Preclinical Veterinary Sciences, University of Edinburgh, United 
      Kingdom.
FAU - Zachary, S
AU  - Zachary S
LA  - eng
GR  - Wellcome Trust/United Kingdom
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
SB  - IM
MH  - Animals
MH  - Cats
MH  - Electrophysiology
MH  - Neurons, Afferent/*physiology
MH  - Spinal Cord/*cytology
EDAT- 1990/01/01 00:00
MHDA- 1990/01/01 00:01
CRDT- 1990/01/01 00:00
PHST- 1990/01/01 00:00 [pubmed]
PHST- 1990/01/01 00:01 [medline]
PHST- 1990/01/01 00:00 [entrez]
AID - 10.1152/jn.1990.63.1.1 [doi]
PST - ppublish
SO  - J Neurophysiol. 1990 Jan;63(1):1-15. doi: 10.1152/jn.1990.63.1.1.