Activity of the Motor Cortex During Scratching

2006 ◽  
Vol 95 (2) ◽  
pp. 753-765 ◽  
Author(s):  
Mikhail G. Sirota ◽  
Galina A. Pavlova ◽  
Irina N. Beloozerova
Keyword(s):  
Motor Cortex ◽  
Hind Limb ◽  
Pyramidal Tract ◽  
Average Depth ◽  
Simple Correlation ◽  
Population Activity ◽  
Ankle Muscles ◽  
Pyramidal Tract Neurons ◽  
Awake Cats ◽  
Stimulation Of

In awake cats sitting with the head restrained, scratching was evoked using stimulation of the ear. Cats scratched the shoulder area, consistently failing to reach the ear. Kinematics of the hind limb movements and the activity of ankle muscles, however, were similar to those reported earlier in unrestrained cats. The activity of single neurons in the hind limb representation of the motor cortex, including pyramidal tract neurons (PTNs), was examined. During the protraction stage of the scratch response, the activity in 35% of the neurons increased and in 50% decreased compared with rest. During the rhythmic stage, the motor cortex population activity was approximately two times higher compared with rest, because the activity of 53% of neurons increased and that of 33% decreased in this stage. The activity of 61% of neurons was modulated in the scratching rhythm. The average depth of frequency modulation was 12.1 ± 5.3%, similar to that reported earlier for locomotion. The phases of activity of different neurons were approximately evenly distributed over the scratch cycle. There was no simple correlation between resting receptive field properties and the activity of neurons during the scratch response. We conclude that the motor cortex participates in both the protraction and the rhythmic stages of the scratch response.

scholarly journals Slowly-conducting pyramidal tract neurons in macaque and rat

2019 ◽  
Author(s):  
A Kraskov ◽  
D Soteropoulos ◽  
I Glover ◽  
RN Lemon ◽  
SN Baker
Keyword(s):  
Motor Cortex ◽  
Pyramidal Tract ◽  
Recurrent Inhibition ◽  
Anatomical Studies ◽  
Slow Conduction ◽  
Pyramidal Tract Neurons ◽  
Conduction Velocities ◽  
Myelinated Fibres ◽  
Anaesthetised Rats

SummaryAnatomical studies report a large proportion of fine myelinated fibres in the primate pyramidal tract (PT), while very few pyramidal tract neurons (PTNs) with slow conduction velocities (CV) (< ∼10 m/s) are reported electrophysiologically. This discrepancy might reflect recording bias towards fast PTNs or prevention of antidromic invasion by recurrent inhibition of slow PTNs from faster axons. We investigated these factors in recordings made with a polyprobe (32 closely-spaced contacts) from motor cortex of anaesthetised rats (n=2) and macaques (n=3), concentrating our search on PTNs with long antidromic latencies. We identified 21 rat PTNs with antidromic latencies > 2.6 ms and estimated CV 3-8 m/s, and 67 macaque PTNs (> 3.9ms, CV 6-12 m/s). Spikes of most slow PTNs were small and present on only some recording contacts, while spikes from simultaneously recorded fast-conducting PTNs were large and appeared on all contacts. Antidromic thresholds were similar for fast and slow PTNS, while spike duration was considerably longer in slow PTNs. Most slow PTNs showed no signs of failure to respond antidromically. A number of tests, including intracortical microinjection of bicuculline (GABAA antagonist), failed to provide any evidence that recurrent inhibition prevented antidromic invasion of slow PTNs. Our results suggest that recording bias is the main reason why previous studies were dominated by fast PTNs.

scholarly journals Inhibitory influence of the ipsilateral motor cortex on responses to stimulation of the human cortex and pyramidal tract

1998 ◽  
Vol 510 (1) ◽  
pp. 249-259 ◽  
Author(s):  
Christian Gerloff ◽  
Leonardo G. Cohen ◽  
Mary Kay Floeter ◽  
Robert Chen ◽  
Brian Corwell ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Pyramidal Tract ◽  
Inhibitory Influence ◽  
Human Cortex ◽  
Stimulation Of

Contribution of the Motor Cortex to the Structure and the Timing of Hindlimb Locomotion in the Cat: A Microstimulation Study

2005 ◽  
Vol 94 (1) ◽  
pp. 657-672 ◽  
Author(s):  
Frédéric Bretzner ◽  
Trevor Drew
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Pyramidal Tract ◽  
Cycle Duration ◽  
Step Cycle ◽  
Standard Glass ◽  
Level Of Activity ◽  
Flexor Muscles ◽  
Multijoint Movements ◽  
Stimulation Of

We used microstimulation to examine the contribution of the motor cortex to the structure and timing of the hindlimb step cycle during locomotion in the intact cat. Stimulation was applied to the hindlimb representation of the motor cortex in 34 sites in three cats using either standard glass-insulated microelectrodes (16 sites in 1 cat) or chronically implanted microwire electrodes (18 sites in 2 cats). Stimulation at just suprathreshold intensities with the cat at rest produced multijoint movements at a majority of sites (21/34, 62%) but evoked responses restricted to a single joint, normally the ankle, at the other 13/34 (38%) sites. Stimulation during locomotion generally evoked larger responses than the same stimulation at rest and frequently activated additional muscles. Stimulation at all 34 sites evoked phase-dependent responses in which stimulation in swing produced transient increases in activity in flexor muscles while stimulation during stance produced transient decreases in activity in extensors. Stimulation with long (200 ms) trains of stimuli in swing produced an increased level of activity and duration of flexor muscles without producing changes in cycle duration. In contrast, stimulation during stance decreased the duration of the extensor muscle activity and initiated a new and premature period of swing, resetting the step cycle. Stimulation of the pyramidal tract in two of these three cats as well as in two additional ones produced similar effects. The results show that the motor cortex is capable of influencing hindlimb activity during locomotion in a similar manner to that seen for the forelimb.

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