Evoked potentials from cat cerebellum following non-medullated C fiber stimulation of peripheral nerve (original) (raw)
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The Journal of Physiology, 1984
1. Previous studies of input on to spinocervical tract neurones have been extended by investigating the post-synaptic actions of non-cutaneous afferent fibres and of descending tracts on to these neurones, using intracellular recording. In particular, actions of group II muscle, joint and Pacinian afferent fibres and rubro-and corticospinal tract fibres were investigated. 2. Group II muscle afferent fibres evoked excitation and inhibition at a minimal latency compatible with a disynaptic linkage. Increasing the stimulus strength to include group III afferent fibres enhanced these post-synaptic actions only modestly. Inhibition was evoked less frequently and/or required trains of stimuli. 3. Weak stimulation of the interosseous nerve evoked short latency (disynaptic) inhibition or excitation, the latter less frequently. Post-synaptic potentials evoked below threshold for group III afferent fibres of the interosseous nerve are attributed to the actions of Pacinian corpuscles. 4. Low threshold joint afferent fibres evoked excitation at short latency. Higher threshold joint afferent fibres usually evoked inhibition at longer latency, although high threshold excitation was sometimes observed. 5. Stimulation of the pyramidal tract evoked constant latency, unitary e.p.s.p.s which followed high frequencies. The evidence suggests that such e.p.s.p.s are evoked monosynaptically. Polysynaptic excitation and inhibition were also observed. 6. No convincing evidence could be found of actions evoked directly by the rubrospinal tract, although actions mediated via other descending systems could be induced from the red nucleus. 7. A large degree of convergence was seen from different peripheral and descending systems on to individual neurones.
The Cerebellum 9 218 231, 2010
In the present study, a non-pulsatile arterially perfused hindbrain and upper body rat preparation is described which is an extension of the brainstem preparation reported by Potts et al., (Brain Res Bull 53(1):59-67), 1. The modified in situ preparation allows study of cerebellar function whilst preserving the integrity of many of its interconnections with the brainstem, upper spinal cord and the peripheral nervous system of the head and forelimbs. Evoked mossy fibre, climbing fibre and parallel fibre field potentials and EMG activity elicited in forelimb biceps muscle by interpositus stimulation provided evidence that both cerebellar inputs and outputs remain operational in this preparation. Similarly, the spontaneous and evoked single unit activity of Purkinje cells, putative Golgi cells, molecular interneurones and cerebellar nuclear neurones was similar to activity patterns reported in vivo. The advantages of the preparation include the ability to record, without the complications of anaesthesia, stabile single unit activity for extended periods (3 h or more), from regions of the rat cerebellum that are difficult to access in vivo. The preparation should therefore be a useful adjunct to in vitro and in vivo studies of neural circuits underlying cerebellar contributions to movement control and motor learning.
Myelinated fiber types in the superficial radial nerve of the cat and their central projections
Brain Research, 1974
Systematic examination and classification of primary afferent fibers in hindlimb cutaneous nerves of the cat has provided a comprehensive understanding of the fiber types present and their central projection patternsZ-4,v-a,14,1a, 19. This has aided investigations of the properties of second-order neurons receiving primary afferent input 1,z,5,6,1°-lz,17,19. Less is known about fiber types in cat forelimb cutaneous nerves, particularly those innervating haired skin. The process of fiber classification itself has received relatively little attention.
Electroencephalography and clinical neurophysiology, 1996
The purpose of this study was to standardize the method of spinal cord monitoring with evoked potentials in the rat. Seventeen male Wistar rats were anesthetized with alpha-chloralose and urethane. Somatosensory evoked potential (SEP) and cerebellar evoked potential (CEP) following sciatic nerve stimulation were mapped at different time points after induction of anesthesia. SEP peaks at latencies of 13-18 ms (P13, N18) were localized to an extremely small area over the sensory cortex. In contrasts, a negative peak of the SEP at 11 ms (N11) and the CEP were widely distributed over the cerebral or cerebellar surface. Anesthesia significantly influenced the cortical components of the SEP. In 10 rats, MEP or posterior fossa evoked potential (PFEP) following stimulation of the sensorimotor or cerebellar cortices respectively, were recorded at T9. Stimulation of different points produced little change on the waveforms of the MEP or PFEP. Successive recordings of MEP and SEP revealed that ...
Evoked potentials from direct cerebellar stimulation for monitoring of the rodent spinal cord
Journal of Neurosurgery, 1992
✓ Although the assessment of spinal cord function by electrophysiological techniques has become important in both clinical and research environments, current monitoring methods do not completely evaluate all tracts in the spinal cord. Somatosensory and motor evoked potentials primarily reflect dorsal column and pyramidal tract integrity, respectively, but do not directly assess the status of the ventral funiculus. The present study was undertaken to evaluate the use of evoked potentials, elicited by direct cerebellar stimulation, in monitoring the ventral component of the rodent spinal cord. Twenty-nine rats underwent epidural anodal stimulation directly over the cerebellar cortex, with recording of evoked responses from the lower thoracic spinal cord, both sciatic nerves, and/or both gastrocnemius muscles. Stimulation parameters were varied to establish normative characteristics. The pathways conducting these “posterior fossa evoked potentials” were determined after creation of var...
Climbing fibres projecting to cat cerebellar anterior lobe activated by cutaneous A and C fibres
The Journal of physiology, 1987
1. Climbing fibre responses evoked on stimulation of the ipsilateral superficial radial nerve were examined in the forelimb area of the C3 zone in the barbiturate-anaesthetized cat. Climbing fibre responses were recorded in sixty-five Purkinje cells and as field potentials from the surface of the cerebellum. 2. In addition to the previously described A beta-fibre-evoked climbing fibre response, late climbing fibre responses were consistently evoked in all Purkinje cells studied when C fibres were stimulated. The latencies of the A beta- and C-fibre-evoked climbing fibre responses were 11-20 ms and 110-220 ms, respectively. In most experiments climbing fibre responses with an intermediate latency (20-30 ms) were evoked. It was demonstrated that this response depended on A delta fibres. 3. The long-latency climbing fibre response generated by electrical stimulation at C-fibre strength was evoked also during selective anodal block of conduction in A fibres (Brown & Hamman, 1972). Hence...
Acta neurobiologiae experimentalis, 2002
Patterns of afferent connections from receptors of the distal forelimb were investigated in neurones located in C6-C7 segments of the spinal cord with branching axons projecting to the lateral reticular nucleus and the cerebellum. Experiments were made on five adult cats under alpha-chloralose anaesthesia. After antidromic identification, EPSPs and IPSPs were recorded from 22 neurones following stimulation of deep radial, superficial radial, median and ulnar nerves. Both excitatory and inhibitory effects were found in the majority of the cells, however, in 2 cases no synaptic actions were recorded. EPSPs were evoked from group I or II muscle, or cutaneous afferents - mostly monosynaptically. IPSPs from muscle, cutaneous or flexor reflex afferents were mostly polysynaptic. Seven various types of convergence were established in the cells investigated. Significance of parallel transmission of integrated information from various receptors of the distal forelimb to the reticular formatio...