PMID- 4346990
OWN - NLM
STAT- MEDLINE
DCOM- 19730406
LR  - 20190511
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 228
IP  - 2
DP  - 1973 Jan
TI  - Synaptic action on Clarke's column neurones in relation to afferent terminal 
      size.
PG  - 343-60
AB  - 1. Excitatory post-synaptic potentials (e.p.s.p.s) were recorded intracellularly 
      from Clarke's column neurones (DSCT neurones) of the cat in response to adequate 
      stimuli applied to a variety of sensory receptors.2. The amplitude of e.p.s.p.s 
      so produced varied from less than 0.2 mV to more than 2-3 mV. The amplitude 
      distribution of e.p.s.p.s suggested that the mean number of ;quanta' of 
      transmitter released by one impulse varied widely from one fibre to another 
      arising from a given type of sensory receptor.3. The average amplitude of 
      e.p.s.p.s evoked by single afferent impulses was significantly smaller for 
      cutaneous inputs than for muscle or joint inputs. However, synaptic action on 
      DSCT neurones produced by different sensory inputs was equally greater, on the 
      average, than that on spinal motoneurones.4. Both small and large e.p.s.p.s in 
      DSCT neurones failed to increase in amplitude during post-synaptic 
      hyperpolarization applied through the cell body. This failure could not be 
      attributed to possible anomalous rectification in the post-synaptic membrane.5. 
      Small and large e.p.s.p.s were comparable in half-decay time, but there was a 
      positive correlation between amplitude and time-to-peak of e.p.s.p.s. It is 
      suggested that the locations of synapses responsible for small and large 
      e.p.s.p.s are intermingled on the dendrites and that large e.p.s.p.s are 
      associated with a longer duration of transmitter action than small e.p.s.p.s.6. 
      Degenerating terminals of primary afferent fibres on DSCT neurones and 
      motoneurones were examined with the electron microscope after chronic section of 
      the dorsal roots.7. Dendritic degenerating terminals showed no significant 
      difference in size between motoneurones and DSCT neurones. Degenerating ;giant' 
      terminals were found on DSCT neurones, but they were located only on or very 
      close to the cell body.8. It is concluded that the major factor responsible for a 
      large number of ;quanta' of transmitter released at synapses on DSCT neurones is 
      the number of multiple synaptic contacts formed by one afferent fibre rather than 
      the size of individual synapses.
FAU - Kuno, M
AU  - Kuno M
FAU - Munoz-Martinez, E J
AU  - Munoz-Martinez EJ
FAU - Randic, M
AU  - Randic M
LA  - eng
PT  - Journal Article
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
SB  - IM
MH  - Animals
MH  - Cats
MH  - Electrophysiology
MH  - Microscopy, Electron
MH  - Mitochondria
MH  - Motor Neurons/physiology
MH  - Muscles/innervation
MH  - Nerve Degeneration
MH  - Nerve Endings/anatomy & histology
MH  - Neurons/*physiology
MH  - Neurons, Afferent/physiology
MH  - Sensory Receptor Cells/physiology
MH  - Skin/innervation
MH  - Spinal Cord/*physiology
MH  - *Synaptic Transmission
MH  - Time Factors
PMC - PMC1331301
EDAT- 1973/01/01 00:00
MHDA- 1973/01/01 00:01
PMCR- 1974/01/01
CRDT- 1973/01/01 00:00
PHST- 1973/01/01 00:00 [pubmed]
PHST- 1973/01/01 00:01 [medline]
PHST- 1973/01/01 00:00 [entrez]
PHST- 1974/01/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1973.sp010090 [doi]
PST - ppublish
SO  - J Physiol. 1973 Jan;228(2):343-60. doi: 10.1113/jphysiol.1973.sp010090.