Journal of neurophysiology
-
Clinical Trial Controlled Clinical Trial
Proprioceptive coordination of movement sequences: role of velocity and position information.
1. Recent studies have shown that the CNS uses proprioceptive information to coordinate multijoint movement sequences; proprioceptive input related to the kinematics of one joint rotation in a movement sequence can be used to trigger a subsequent joint rotation. In this paper we adopt a broad definition of "proprioception," which includes all somatosensory information related to joint posture and kinematics. ⋯ The results from experiments with unpredictable velocity trajectories indicate that the CNS extracts proprioceptive information related to both the velocity and the angular position of the joint to trigger the hand movement in this movement sequence. 4. To determine the generality of proprioceptive triggering in movement sequences, we estimated the minimal movement duration with which proprioceptive information can be used as well as the amount of learning required to use proprioceptive input to perform the task. The temporal limits for proprioceptive processing in this movement task were established by determining the minimal movement time during which the task could be performed.(ABSTRACT TRUNCATED AT 400 WORDS)
-
1. Neurons (n = 142) were recorded with extracellular micropipettes in the parabrachial (PB) area, in the anesthetized rat, some of them being antidromically driven from the centralis nucleus of the amygdala (Ce). The spontaneous activity of these neurons was low, (10th percentile < median frequency < 90th percentile; 0.01 < 0.3 < 11 Hz), and the activity of a very high proportion of the PB neurons (89%, 127/142) were affected by mechanical or thermal cutaneous stimuli almost exclusively in the noxious range; most of them were activated and received inputs from A delta and/or C fibers. 2. ⋯ The visceral activated neurons exhibited a clear capacity to encode the colorectal distension in noxious range: 1) the stimulus-response function was almost always positive and monotonic; 2) as for the individual curves, the slope of the mean curve progressively increased up to the highest interval of pressure tested (100-125 mmHg); and 3) the threshold for neuronal response to colorectal distension was between 25-100 mmHg with a mean pressure threshold of 56 +/- 24 (SD) mmHg (n = 19). Viscerosomatic convergence was observed for 84% of these neurons: they were also activated by thermal and/or mechanical cutaneous noxious stimuli while only 16% of them were activated only by visceral noxious stimulation. 4. Thirty-one percent (44/142) of the whole population of PB neurons were inhibited by both strong colorectal distension and intraperitoneal bradykinin (82%) or only by one of the stimuli being unresponsive to the other (18%).(ABSTRACT TRUNCATED AT 400 WORDS)
-
1. Discharges of neurons in the peripheral auditory system contain information about the temporal features of acoustic stimuli. Phase-locking of neurons in the anteroventral cochlear nucleus (AVCN) is usually reported to be less robust than in auditory nerve (AN) fibers, which provide their major input. ⋯ For a subset of these fibers (1/3 in total: 23 of 70) phase-locking was higher than is ever observed in the AN (R500 > or = 0.95); these fibers were defined as showing synchronization "enhancement." Virtually all fibers showing synchronization enhancement had primary-like-with-notch (PLN) PST histograms. Chopper and primary-like fibers showed high-sync tails for CFs > 3 kHz. 5. Synchronization filter functions were obtained for high-CF AN fibers by determining maximum synchronization for a range of stimuli below CF.(ABSTRACT TRUNCATED AT 400 WORDS)
-
1. The goal of this study was to gather data that would increase our understanding of nociceptive processing by spinothalamic tract (STT) neurons that receive inputs from the hand and arm. Fifty neurons in the cervical enlargement of urethan-anesthetized rats were antidromically activated from the contralateral posterior thalamus. ⋯ WDR and HT neurons were recorded in both the SDH and DDH, including nucleus proprius, an area not typically associated with nociceptive transmission at other levels of the cord. Sixty percent (9/15) of the units recorded in the SDH were classified as WDR neurons; the other 40% (6/15) were classified HT. Forty-eight percent (15/31) of the units recorded in the DDH were classified as WDR neurons and 42% (13/31) as HT.(ABSTRACT TRUNCATED AT 400 WORDS)
-
1. Neurophysiological recordings were undertaken to determine how neurons in the central nucleus of the inferior colliculus (ICc) of the little brown bat, Myotis lucifugus, extract amplitude modulations that span across a series of tone pulses (i.e., signals that simulate echoes from fluttering targets). Two types of stimuli were presented to the bats. ⋯ In contrast, PL neurons showed mostly high-pass response functions, but one third displayed band-pass response functions. 4. The ability of ICc neurons to time-lock their discharges to the individual pulses in a train was characterized by using the synchronization coefficient (SC) as a measure. The SC was plotted against the repetition rate to construct units' synchronization-based response function.(ABSTRACT TRUNCATED AT 400 WORDS)