Task-dependent presynaptic inhibition.
نویسندگان
چکیده
This study compares the level of presynaptic inhibition during two rhythmic movements in the cat: locomotion and scratch. Dorsal rootlets from L6, L7, or S1 segments were cut, and their proximal stumps were recorded during fictive locomotion occurring spontaneously in decerebrate cats and during fictive scratch induced by d-tubocurarine applied on the C1 and C2 segments. Compared with rest, the number of antidromic spikes was increased (by 12%) during locomotion, whereas it was greatly decreased (31%) during scratch, and the amplitude of dorsal root potentials (DRPs), evoked by stimulating a muscle nerve, was slightly decreased (7%) during locomotion but much more so during scratch (53%). When compared with locomotion, the decrease in the number of antidromic spikes (45%) and the decrease in DRP amplitude (43%) during scratch were of similar magnitude. Also, the amplitude of primary afferent depolarization (PAD), recorded with micropipettes in axons (n = 13) of two cats, was found to be significantly reduced (60%) during scratch compared with rest. During both rhythms, there were cyclic oscillations in dorsal root potential the timing of which was linearly related to the timing of rhythmic activity in tibialis anterior. The amplitude of these oscillations was significantly smaller (34%) during locomotion compared with scratch. These results suggest that the reduction in antidromic activity during scratch was attributable to a task-dependent decrease in transmission in PAD pathways and not to underlying potential oscillations related to the central pattern generator. It is concluded that presynaptic inhibition and antidromic discharge may have a more important role in the control of locomotion than scratch.
منابع مشابه
Task- and time-dependent modulation of Ia presynaptic inhibition during fatiguing contractions performed by humans.
Presynaptic modulation of Ia afferents converging onto the motor neuron pool of the extensor carpi radialis (ECR) was compared during contractions (20% of maximal force) sustained to failure as subjects controlled either the angular position of the wrist while supporting an inertial load (position task) or exerted an equivalent force against a rigid restraint (force task). Test Hoffmann (H) ref...
متن کاملBrief Communication GABAB Receptor-Mediated Presynaptic Inhibition Has History-Dependent Effects on Synaptic Transmission during Physiologically Relevant Spike Trains
Presynaptic inhibition is a form of neuromodulation that interacts with activity-dependent short-term plasticity so that the magnitude, and sometimes even the polarity, of that activity-dependent short-term plasticity is changed. However, the functional consequences of this interaction during physiologically relevant spike trains are poorly understood. We examined the effects of presynaptic inh...
متن کاملEFFECTS OF CATECHOLAMINES ON DOPAMINE AND SEROTONIN SYNTHESIS IN RAT BRAIN STRIATAL SYNAPTOSOMES: THE ROLE OF PRESYNAPTIC RECEPTORS AND THE SYNAPTOSOMAL REUPTAKE MECHANISM.
The regulation of dopamine and serotonin synthesis in rat brain striatal synaptosomes has been studied using HPLC methods. Noradrenaline was shown to markedly inhibit both the synthesis of dopamine and serotonin. The response of the synaptosomes to the concentrations of noradrenaline appeared to be biphasic, a very effective inhibition occurring at low concentrations (1-5 µm) and a relativ...
متن کاملTask-related changes in intracortical inhibition assessed with paired- and triple-pulse transcranial magnetic stimulation.
Recent research has demonstrated a task-related modulation of postsynaptic intracortical inhibition within primary motor cortex for tasks requiring isolated (abduction) or synergistic (precision grip) muscle activation. The current study sought to investigate task-related changes in pre- and postsynaptic intracortical inhibition in motor cortex. In 13 young adults (22.5 ± 3.5 yr), paired-pulse ...
متن کاملFunctional consequences of presynaptic inhibition during behaviorally relevant activity.
Presynaptic inhibition is a widespread mechanism for regulating transmitter release in the CNS. Presynaptic inhibitors act as a high-pass filter, but the functional consequence of this filtering during the synaptic processing of behaviorally relevant activity remains unknown. Here we use analytical approaches to examine the effects of presynaptic inhibition on synaptic output in response to act...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of neuroscience : the official journal of the Society for Neuroscience
دوره 23 5 شماره
صفحات -
تاریخ انتشار 2003