scholarly journals Synaptic Linkages Between Corticomotoneuronal Cells Affecting Forelimb Muscles in Behaving Primates

2009 ◽  
Vol 102 (2) ◽  
pp. 1040-1048 ◽  
Author(s):  
W. S. Smith ◽  
E. E. Fetz
Keyword(s):  
Motor Cortex ◽  
Synaptic Input ◽  
Action Potentials ◽  
The Other ◽  
Response Patterns ◽  
Cortical Cells ◽  
Synaptic Interactions ◽  
Corticomotoneuronal Cells ◽  
Synergistic Muscles ◽  
Forelimb Muscles

To elucidate the cortical circuitry controlling primate forelimb muscles we investigated the synaptic interactions between neighboring motor cortex cells that had postspike output effects in target muscles. In monkeys generating isometric ramp-and-hold wrist torques, pairs of cortical cells were recorded simultaneously with independent electrodes and corticomotoneuronal (“CM”) cells were identified by their postspike effects on target forelimb muscles in spike-triggered averages (SpTAs) of electromyographs (EMGs). The response patterns of the cells were determined in response-aligned averages and their synaptic interactions were identified by cross-correlograms of action potentials. The possibility that synchronized firing between cortical cells could mediate spike-correlated effects in the SpTA of EMG was examined in several ways. Sixty-two pairs consisted of one CM cell and a non-CM cell; 15 of these had correlogram peaks of the same magnitude as that of other pairs, but the synchrony peaks did not mediate any postspike effect from the non-CM cell. Twelve pairs of simultaneously recorded CM cells were cross-correlated. Half had features (usually synchrony peaks) in their cross-correlograms and the cells of these pairs also shared some target muscles in common. The other half had flat correlograms and, in most of these pairs, the CM cells affected different muscles. The latter group included pairs of CM cells that facilitated synergistic muscles. These results indicate that common synaptic input specifically affects CM cells that have overlapping muscle fields. Reconstruction of the cortical locations of CM cells affecting 12 different muscles showed a wide and overlapping distribution of cortical colonies of forelimb muscles.

scholarly journals Synaptic Interactions Between Forelimb-Related Motor Cortex Neurons in Behaving Primates

2009 ◽  
Vol 102 (2) ◽  
pp. 1026-1039 ◽  
Author(s):  
W. S. Smith ◽  
E. E. Fetz
Keyword(s):  
Motor Cortex ◽  
Central Peak ◽  
Response Patterns ◽  
Cortical Cells ◽  
Common Input ◽  
Excitatory Connection ◽  
Synaptic Interactions ◽  
Central Trough ◽  
Linear Fit ◽  
Layer V

We investigated the synaptic interactions between neighboring motor cortex cells in monkeys generating isometric ramp-and-hold torques about the wrist. For pairs of cortical cells the response patterns were determined in response-aligned averages and their synaptic interactions were identified by cross-correlation histograms. Cross-correlograms were compiled for 215 cell pairs and 84 (39%) showed significant features. The most frequently found feature (65/84 = 77%) was a central peak, straddling the origin and representing a source of common synaptic input to both cells. One third of these also had superimposed lagged peaks, indicative of a serial excitatory connection. Pure lagged peaks and lagged troughs, indicative of serial excitatory or inhibitory linkages, respectively, both occurred in 5% of the correlograms with features. A central trough appeared in 13% of the correlograms. The magnitude of the synaptic linkage was measured as the normalized area of the correlogram feature. Plotting the strength of synaptic interaction against response similarity during alternating wrist torques revealed a positive relationship for the correlated cell pairs. A linear fit yielded a positive slope: the pairs with excitatory interactions tended to covary more often than countervary. This linear fit had a positive offset, reflecting a tendency for both covarying and countervarying cells to have excitatory common input. Plotting the cortical location of the cell pairs showed that the strongest interactions occurred between cells separated by <400 microns. The correlational linkages between cells of different cortical layers showed a large proportion of common input to cells in layer V.

Identifiable neurons controlling penile eversion in the leech

1979 ◽  
Vol 42 (2) ◽  
pp. 455-464 ◽  
Author(s):  
B. Zipser
Keyword(s):  
Motor Neurons ◽  
Synaptic Input ◽  
Reproductive Behavior ◽  
Action Potentials ◽  
Muscle Fibers ◽  
Ventral Side ◽  
The Other ◽  
Electrophysiological Evidence ◽  
Electrophysiological Studies ◽  
Male Organ

1. This paper describes the neuroanatomy and electrophysiology of motor neurons causing penile eversion in the leech. 2. The male organ is innervated by ganglia 5 and 6 of the 34 ganglia in the leech brain through special sex nerves deriving from anterior roots. These sex ganglia have at least 200 more neurons than the other midbody ganglia. Many of the extra neurons are involved in reproductive behavior. 3. Two pairs of motor neurons on the ventral side of ganglion 6, named rostral and lateral neurons, are the only ones that elicit full penile eversion. Evidence that the lateral and rostral neurons are, in fact, motor neurons comes from HRP and electrophysiological studies. HRP injections reveal that each neuron's single primary axon grows into the sex nerve. Electrophysiological evidence is twofold: a) action potentials of lateral and rostral cells can still contract the genitalia after the neurons are deafferented from chemical synaptic input in the ganglion by high Mg2+, b) their action potentials are followed by junction potentials in male organ muscle fibers.

Comparable patterns of muscle facilitation evoked by individual corticomotoneuronal (CM) cells and by single intracortical microstimuli in primates: evidence for functional groups of CM cells

1985 ◽  
Vol 53 (3) ◽  
pp. 786-804 ◽  
Author(s):  
P. D. Cheney ◽  
E. E. Fetz
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Action Potentials ◽  
Relative Strength ◽  
Emg Activity ◽  
Base Line ◽  
Onset Latency ◽  
Wrist Flexion ◽  
Forelimb Muscles ◽  
The Mean

We compared the averaged responses of forelimb muscles to action potentials of single motor cortex cells and to single intracortical microstimuli (S-ICMS). Activity of precentral neurons and 12 identified forelimb muscles (6 flexors and 6 extensors of wrist and fingers) was recorded in macaques while they performed alternating ramp-and-hold wrist movements. Action potentials of cells that covaried reliably with wrist flexion or extension were used to compile spike-triggered averages (spike-TAs) of rectified electromyographic (EMG) activity of six synergistically coactivated muscles. Cells whose spikes were followed by a clear postspike facilitation (PSF) of rectified muscle activity were designated corticomotoneuronal (CM) cells. CM cells typically facilitated a subset of the coactivated muscles called the cell's target muscles. The relative strength of the PSF in different target muscles ranged from clear increases above base-line fluctuations to weak but significant effects. For each CM cell we characterized the "PSF profile" of facilitation across different muscles, defined as the relative strength of PSF in each of the coactivated agonist muscles. After identifying the CM cell's target muscles, we delivered S-ICMS through the microelectrode at the same site. Biphasic stimuli were delivered during the same wrist movements in which the recorded CM cell had been active. Stimulus intensities were too weak (typically 5-10 microA) and their repetition rate too slow (5-15 Hz) to evoke muscle excitation evident in the raw EMG record. However, stimulus-triggered averages (stimulus-TAs) of the rectified EMGs of coactivated muscles revealed consistent patterns of poststimulus facilitation (PStimF). In most cases the muscles facilitated by the CM cell in spike-TAs (n = 60) were also facilitated by S-ICMS in stimulus-TAs. At sites of CM cells the threshold stimulus intensities for evoking a statistically significant effect were between 0.5 and 2 microA. S-ICMS of 5 microA evoked PStimF that was, on the average, six times stronger than the PSF of the CM cell. The height of the facilitation peak relative to base-line fluctuations was 5-60 times greater for the stimuli than the spikes of the CM cell. The average onset latency of PStimF (8.0 +/- 1.2 ms) was 1.3 ms longer than the mean latency of PSF (6.7 +/- 1.4 ms). At two-thirds of the cortical sites where both spike- and stimulus-TAs were computed (n = 30), the PStimF profile exactly matched the PSF profile.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Stability of Output Effects from Motor Cortex to Forelimb Muscles in Primates

2009 ◽  
Vol 29 (6) ◽  
pp. 1915-1927 ◽  
Author(s):  
D. M. Griffin ◽  
H. M. Hudson ◽  
A. Belhaj-Saif ◽  
P. D. Cheney
Keyword(s):  
Motor Cortex ◽  
Forelimb Muscles

Electrical interactions between the giant axons of a polychaete worm (Sabella penicillus L.)

1980 ◽  
Vol 84 (1) ◽  
pp. 119-136
Author(s):  
D. Mellon ◽  
J. E. Treherne ◽  
N. J. Lane ◽  
J. B. Harrison ◽  
C. K. Langley
Keyword(s):  
Safety Factor ◽  
Nerve Cord ◽  
Action Potentials ◽  
Divalent Cations ◽  
Muscular Contraction ◽  
The Body ◽  
The Other ◽  
Intracellular Recordings ◽  
Giant Axons ◽  
Other Hand

Intracellular recordings demonstrated a transfer of impulses between the paired giant axons of Sabella, apparently along narrow axonal processes contained within the paired commissures which link the nerve cords in each segment of the body. This transfer appears not to be achieved by chemical transmission, as has been previously supposed. This is indicated by the spread of depolarizing and hyperpolarizing voltage changes between the giant axons, the lack of effects of changes in the concentrations of external divalent cations on impulse transmission and by the effects of hyperpolarization in reducing the amplitude of the depolarizing potential which precedes the action potentials in the follower axon. The ten-to-one attenuation of electronic potentials between the giant axons argues against the possibility of an exclusively passive spread of potential along the axonal processes which link the axons. Observation of impulse traffic within the nerve cord commissures indicates, on the other hand, that transmission is achieved by conduction of action potentials along the axonal processes which link the giant axons. At least four pairs of intact commissures are necessary for inter-axonal transmission, the overall density of current injected at multiple sites on the follower axon being, it is presumed, sufficient to overcome the reduction in safety factor imposed by the geometry of the system in the region where axonal processes join the giant axons. The segmental transmission between the giant axons ensures effective synchronization of impulse traffic initiated in any region of the body and, thus, co-ordination of muscular contraction, during rapid withdrawal responses of the worm.

Neural Patterns Associated with Ventilatory Movements in Dragonfly Larvae

1970 ◽  
Vol 52 (1) ◽  
pp. 167-175
Author(s):  
P. J. MILL
Keyword(s):  
Control System ◽  
Motor Activity ◽  
Action Potentials ◽  
Motor Units ◽  
The Other ◽  
Ventilatory Control ◽  
Expiratory Phase ◽  
Segmental Nerve ◽  
Ventral Muscle ◽  
Stimulation Of

1. Rhythmic bursts of motor activity associated with the expiratory phase of ventilation have been recorded from the second lateral segmental nerves of posterior abdominal ganglia in Aeshna and Anax larvae. 2. In Aeshna the rhythmic expiratory bursts contain one, or sometimes two, motor units; whereas in Anax there are almost invariably three units. In both animals only one unit is associated with action potentials in the respiratory dorso-ventral muscle. 3. Motor activity synchronized with the expiratory bursts in the second nerves has been recorded from the other lateral nerves and from the last unpaired nerve. In addition the fifth lateral nerves carry inspiratory bursts. 4. It has been confirmed that stimulation of a first segmental nerve can re-set the ventilatory rhythm by initiating an expiratory burst in the second nerves. The original frequency is immediately resumed on cessation of stimulation. 5. The nature of the ventilatory control system in dragonfly larvae is discussed in relation to other rhythmic systems in the arthropods.

scholarly journals Independent theta phase coding accounts for CA1 population sequences and enables flexible remapping

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Angus Chadwick ◽  
Mark CW van Rossum ◽  
Matthew F Nolan
Keyword(s):  
Traveling Wave ◽  
Action Potentials ◽  
Theta Rhythm ◽  
Place Cells ◽  
Population Activity ◽  
Phase Coding ◽  
Synaptic Interactions ◽  
Spike Sequences ◽  
Rate Coding ◽  
Theta Phase

Hippocampal place cells encode an animal's past, current, and future location through sequences of action potentials generated within each cycle of the network theta rhythm. These sequential representations have been suggested to result from temporally coordinated synaptic interactions within and between cell assemblies. Instead, we find through simulations and analysis of experimental data that rate and phase coding in independent neurons is sufficient to explain the organization of CA1 population activity during theta states. We show that CA1 population activity can be described as an evolving traveling wave that exhibits phase coding, rate coding, spike sequences and that generates an emergent population theta rhythm. We identify measures of global remapping and intracellular theta dynamics as critical for distinguishing mechanisms for pacemaking and coordination of sequential population activity. Our analysis suggests that, unlike synaptically coupled assemblies, independent neurons flexibly generate sequential population activity within the duration of a single theta cycle.

Ultrastructural features of the sensori-motor cortex of the primate

1979 ◽  
Vol 285 (1006) ◽  
pp. 123-139 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Motor Cortex ◽  
Thin Layer ◽  
Liquid Helium ◽  
Thermal Insulation ◽  
Solid Surfaces ◽  
The Other ◽  
Experimental Chamber ◽  
Short Discussion ◽  
Inside Wall

cooled to 2°K or lower. Rollin (1936) found that the thermal insulation of vessels containing liquid helium was much worse below than above the A point. He explained his observation by assuming the existence of a thin layer of liquid helium on the inside wall of the connecting tube, and thought it probable that the change in thermal conductivity of this film at the A point gave rise to the anomalous effects observed. As the result of more recent (unpublished) experiments Rollin and Simon* have put forward the other explanation that the film creeps up the tube and evaporates eventually. It is obvious that all these phenomena may have a common explanation and it was the object of the experiments described in this paper and the following paper to investigate the behaviour of He 11 in contact with solid surfaces systematically. The phenomena had to be investigated from various aspects and this made experiments necessary which varied in purpose and character to some extent. For simplicity’s sake we will therefore give, together with the description of each experiment, a short discussion and summarize at the end of the second paper all results in a general discussion on the whole phenomenon. All experiments were carried out in the same cryostat; and for different experiments only the experimental chamber and the experimental arrangement in it were altered.

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