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Synaptic actions of peripheral nerve impulses upon Deiters neurones via the climbing fibre afferents
Author(s) -
Allen G. I.,
Sabah N. H.,
Toyama K.
Publication year - 1972
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1972.sp009986
Subject(s) - forelimb , antidromic , hindlimb , anatomy , stimulation , peripheral , inhibitory postsynaptic potential , spinal cord , excitatory postsynaptic potential , neuroscience , lateral funiculus , sensory system , receptive field , biology , chemistry , medicine
1. The cerebellar integration of sensory inputs to Deiters neurones was studied in cats under Nembutal anaesthesia. 2. Stimulation of peripheral nerves produced in the Deiters neurones a sequence of an initial excitatory post‐synaptic potential (e.p.s.p.) and a later inhibitory post‐synaptic potential (i.p.s.p.), or a relatively small e.p.s.p. 3. The Deiters neurones were classified as forelimb (FL)‐ or hind limb (HL)‐type cells according to the location of the most effective peripheral nerve. In the FL cells stimulation of the forelimb nerves produced the e.p.s.p.—i.p.s.p. sequence (dominant response), while stimulation of the hind limb nerves was ineffective or produced the small e.p.s.p. (non‐dominant response). In contrast, in the HL cells the non‐dominant response was evoked from the forelimb nerves, and the dominant response from the hind limb nerves. 4. The stimulus intensity—response relation indicates that Group I and II muscle afferents and low and high threshold cutaneous afferents contribute to the dominant and non‐dominant responses. 5. Antidromic identification of these Deiters neurones revealed that 90% of the HL cells and 85% of the FL cells project to the lumbo‐sacral and cervico‐thoracic segments of the spinal cord, respectively, while 10% of the HL cells and 15% of the FL cells innervate the cervico‐thoracic and lumbo‐sacral segments, respectively. 6. The mean latency of the e.p.s.p. evoked from the forelimb nerves was 14 msec in the FL cells and 13 msec in the HL cells, and the latency of the e.p.s.p. evoked from the hind limb nerves was 17 msec in the FL cells and 18 msec in the HL cells. The later i.p.s.p. regularly followed the onset of the e.p.s.p. with a delay of 3–5 msec. 7. The dominant and non‐dominant responses in both types of cells exhibited the following three characteristic features: (i) a strong depression after conditioning stimulation of the inferior olive, (ii) an increase of the inferior olivary excitability during the responses, and (iii) a striking frequency depression with stimulation at relatively low frequency (5–10/sec). 8. Consequently it was concluded that all of the responses were produced through the climbing fibres originating from the inferior olive, the i.p.s.p.s due to inhibition from Purkyně cells activated by the climbing fibres and the e.p.s.p.s due to excitation from the collaterals of the climbing fibres.