Monkey flexor and abductor pollicis brevis motoneuron pools: Proximal dendritic trees and small motoneurons.

Transverse sections of the monkey cervical spinal cord from a previous study (Jenny and Inukai, 1983 [1]) were reanalyzed using Neurolucida to create a three-dimensional display of flexor pollicis brevis and abductor pollicis brevis (FAbPBr) motoneurons and dendrites that had been jointly labeled with horse radish peroxidase (HRP). These data were correlated with similar data from a reanalysis of an extensor digitorum communis (EDC) motoneuron pool (Jenny, Cheney, and Jenny, 2018 [2]). The FAbPBr motoneuron columns were located in the C8 (caudal) and T1 segments of the spinal cord and within the most dorsal and medial regions of the motor column pools that innervate hand muscles.

Morphine Potentiates Dysbiotic Microbial and Metabolic Shifts in Acute SIV Infection.

Human Immunodeficiency Virus (HIV) pathogenesis has been closely linked with microbial translocation, which is believed to drive inflammation and HIV replication. Opioid drugs have been shown to worsen this symptom, leading to a faster progression of HIV infection to Acquired Immunodeficiency Syndrome (AIDS). The interaction of HIV and opioid drugs has not been studied at early stages of HIV, particularly in the gut microbiome where changes may precede translocation events.

Muscle Synergies Obtained from Comprehensive Mapping of the Cortical Forelimb Representation Using Stimulus Triggered Averaging of EMG Activity.

Neuromuscular control of voluntary movement may be simplified using muscle synergies similar to those found using non-negative matrix factorization. We recently identified synergies in electromyography (EMG) recordings associated with both voluntary movement and movement evoked by high-frequency long-duration intracortical microstimulation applied to the forelimb representation of the primary motor cortex (M1). The goal of this study was to use stimulus-triggered averaging (StTA) of EMG activity to investigate the synergy profiles and weighting coefficients associated with poststimulus facilitation, as synergies may be hard-wired into elemental cortical output modules and revealed by StTA.

Monkey extensor digitorum communis motoneuron pool: Proximal dendritic trees and small motoneurons.

Transverse sections of the monkey cervical spinal cord from a previous study (Jenny and Inukai, 1983) were reanalyzed using Neurolucida to create a three-dimensional display of extensor digitorum communis (EDC) motoneurons and proximal dendrites that had been labeled with horse radish peroxidase (HRP). The EDC motoneuron pool was located primarily in the C8 and T1 segments of the spinal cord. Small motoneurons (cell body areas less than 500 μm and presumed to be gamma motoneurons) comprised about ten percent of the motoneurons and were located throughout the length of the motoneuron pool.

Perspectives on classical controversies about the motor cortex.

Primary motor cortex has been studied for more than a century, yet a consensus on its functional contribution to movement control is still out of reach. In particular, there remains controversy as to the level of control produced by motor cortex ("low-level" movement dynamics vs. "high-level" movement kinematics) and the role of sensory feedback.

Muscle synergies obtained from comprehensive mapping of the primary motor cortex forelimb representation using high-frequency, long-duration ICMS.

Simplifying neuromuscular control for movement has previously been explored by extracting muscle synergies from voluntary movement electromyography (EMG) patterns. The purpose of this study was to investigate muscle synergies represented in EMG recordings associated with direct electrical stimulation of single sites in primary motor cortex (M1). We applied single-electrode high-frequency, long-duration intracortical microstimulation (HFLD-ICMS) to the forelimb region of M1 in two rhesus macaques using parameters previously found to produce forelimb movements to stable spatial end points (90-150 Hz, 90-150 μA, 1,000-ms stimulus train lengths).

Representation of individual forelimb muscles in primary motor cortex.

Stimulus-triggered averaging (StTA) of forelimb muscle electromyographic (EMG) activity was used to investigate individual forelimb muscle representation within the primary motor cortex (M1) of rhesus macaques with the objective of determining the extent of intra-areal somatotopic organization. Two monkeys were trained to perform a reach-to-grasp task requiring multijoint coordination of the forelimb. EMG activity was simultaneously recorded from 24 forelimb muscles including 5 shoulder, 7 elbow, 5 wrist, 5 digit, and 2 intrinsic hand muscles.

Effects of Morphine on Behavioral Task Performance in SIV-Infected Rhesus Macaques.

The abuse of opiates such as morphine in synergy with HIV infection not only exacerbates neuropathogenesis but significantly impacts behavioral attributes in HIV infected subjects. Thus, the goal of the current study was to characterize behavioral perturbations in rhesus macaques subjected to chronic morphine and SIV infection. Specifically, we assessed three behavioral tasks: motor skill (MS), forelimb force (FFT) and progressive ratio (PR) tasks.

Timing of Cortico-Muscle Transmission During Active Movement.

Numerous studies have reported large disparities between short cortico-muscle conduction latencies and long recorded delays between cortical firing and evoked muscle activity. Using methods such as spike- and stimulus-triggered averaging of electromyographic (EMG) activity, previous studies have shown that the time delay between corticomotoneuronal (CM) cell firing and onset of facilitation of forelimb muscle activity ranges from 6.7 to 9.

Cortical Effects on Ipsilateral Hindlimb Muscles Revealed with Stimulus-Triggered Averaging of EMG Activity.

While a large body of evidence supports the view that ipsilateral motor cortex may make an important contribution to normal movements and to recovery of function following cortical injury (Chollet et al. 1991; Fisher 1992; Caramia et al. 2000; Feydy et al.

Equilibrium-based movement endpoints elicited from primary motor cortex using repetitive microstimulation.

High-frequency, long-duration intracortical microstimulation (HFLD-ICMS) is increasingly being used to deduce how the brain encodes coordinated muscle activity and movement. However, the full movement repertoire that can be elicited from the forelimb representation of primary motor cortex (M1) using this method has not been systematically determined. Our goal was to acquire a comprehensive M1 forelimb representational map of movement endpoints elicited with HFLD-ICMS, using stimulus parameters optimal for evoking stable forelimb spatial endpoints.

Properties of primary motor cortex output to hindlimb muscles in the macaque monkey.

The cortical control of forelimb motor function has been studied extensively, especially in the primate. In contrast, cortical control of the hindlimb has been relatively neglected. This study assessed the output properties of the primary motor cortex (M1) hindlimb representation in terms of the sign, latency, magnitude, and distribution of effects in stimulus-triggered averages (StTAs) of electromyography (EMG) activity recorded from 19 muscles, including hip, knee, ankle, digit, and intrinsic foot muscles, during a push-pull task compared with data reported previously on the forelimb.

Recovery of precision grasping after motor cortex lesion does not require forced use of the impaired hand in Macaca mulatta.

We investigated recovery of precision grasping of small objects between the index finger and thumb of the impaired hand without forced use after surgically placed lesions to the hand/arm areas of M1 and M1 + lateral premotor cortex in two monkeys. The unilateral lesions were contralateral to the monkey's preferred hand, which was established in prelesion testing as the hand used most often to acquire raisins in a foraging board (FB) task in which the monkey was free to use either hand to acquire treats. The lesions initially produced a clear paresis of the contralesional hand and use of only the ipsilesional hand to acquire raisins in the FB task.

EMG activation patterns associated with high frequency, long-duration intracortical microstimulation of primary motor cortex.

The delivery of high-frequency, long-duration intracortical microstimulation (HFLD-ICMS) to primary motor cortex (M1) in primates produces hand movements to a common final end-point regardless of the starting hand position (Graziano et al., 2002). We have confirmed this general conclusion.

Deep brain stimulation lead-contact heating during 3T MRI: single- versus dual-channel pulse generator configurations.

Background: Magnetic resonance imaging (MRI) after deep brain stimulation (DBS) carries the risk of heating at the lead-contacts within the brain.

Objective/hypothesis: To compare the effect of single- and dual-channel DBS implantable pulse generator (IPG) configurations on brain lead-contact heating during 3T MRI.

Methods: A phantom with bilateral brain leads and extensions connected to two single-channel IPGs or a dual-channel right or left IPG was utilized.

Effective intracortical microstimulation parameters applied to primary motor cortex for evoking forelimb movements to stable spatial end points.

High-frequency, long-duration intracortical microstimulation (HFLD-ICMS) applied to motor cortex is recognized as a useful and informative method for corticomotor mapping by evoking natural-appearing movements of the limb to consistent stable end-point positions. An important feature of these movements is that stimulation of a specific site in motor cortex evokes movement to the same spatial end point regardless of the starting position of the limb. The goal of this study was to delineate effective stimulus parameters for evoking forelimb movements to stable spatial end points from HFLD-ICMS applied to primary motor cortex (M1) in awake monkeys.

Cortical output to fast and slow muscles of the ankle in the rhesus macaque.

The cortical control of fast and slow muscles of the ankle has been the subject of numerous reports yielding conflicting results. Although it is generally agreed that cortical stimulation yields short latency facilitation of fast muscles, the effects on the slow muscle, soleus, remain controversial. Some studies have shown predominant facilitation of soleus from the cortex while others have provided evidence of differential control in which soleus is predominantly inhibited from the cortex.

Photoacoustic detection of functional responses in the motor cortex of awake behaving monkey during forelimb movement.

Photoacoustic (PA) imaging was applied to detect the neuronal activity in the motor cortex of an awake, behaving monkey during forelimb movement. An adult macaque monkey was trained to perform a reach-to-grasp task while PA images were acquired through a 30-mm diameter implanted cranial chamber. Increased PA signal amplitude results from an increase in regional blood volume and is interpreted as increased neuronal activity.

Ondansetron oral dissolving tablets are superior to normal saline alone for prehospital nausea.

Background: Antiemetics have been shown to be effective in multiple hospital settings, but few studies have been done in the prehospital environment.

Objectives: Our hypotheses were 1) that the amount of normal saline administered during an emergency medical services (EMS) transport was not related to a change in nausea and vomiting and 2) that the addition of the ondansetron orally disintegrating tablet (ODT) would decrease the degree of nausea.

Methods: This was a pre-post study of two cohorts of consecutive patients with nausea in the prehospital setting.

Enhanced pulmonary arteriopathy in simian immunodeficiency virus-infected macaques exposed to morphine.

Rationale: HIV-associated pulmonary arterial hypertension (PAH) is likely a more prevalent noninfectious complication of AIDS than previously recognized. Furthermore, the majority of HIV-PAH cases occur in individuals with a history of intravenous drug use. In this study we used a simian immunodeficiency (SIV) macaque model and a primary cell-culture system to investigate the association between drug abuse and HIV infection in HIV-PAH development.

The use of chemical restraints reduces agitation in patients transported by emergency medical services.

Background: Agitated patients are the primary source of injury to patients and providers during ambulance transport.

Objective: Our primary hypothesis was that the addition of a chemical restraint agent (midazolam) to a restraint protocol would reduce agitation to a greater extent than a restraint protocol with physical restraint alone.

Methods: The local emergency medical services restraint protocol (RP) was implemented on October 1, 2006.

Hijacking cortical motor output with repetitive microstimulation.

High-frequency repetitive microstimulation has been widely used as a method of investigating the properties of cortical motor output. Despite its widespread use, few studies have investigated how activity evoked by high-frequency stimulation may interact with the existing activity of cortical cells resulting from natural synaptic inputs. A reasonable assumption might be that the stimulus-evoked activity sums with the existing natural activity.

Morphine potentiates neuropathogenesis of SIV infection in rhesus macaques.

Despite the advent of antiretroviral therapy, complications of HIV-1 infection with concurrent drug abuse are an emerging problem. Opiates are well known to modulate immune responses by preventing the development of cell-mediated immune responses. Their effect on the pathogenesis of HIV-1 infection however remains controversial.

Methods for chronic recording of EMG activity from large numbers of hindlimb muscles in awake rhesus macaques.

Studies of the neural control of movement often rely on the ability to record EMG activity during natural behavioral tasks over long periods of time. Increasing the number of recorded muscles and the time over which recordings are made allows more rigorous answers to many questions related to the descending control of motor output. Chronic recording of EMG activity from multiple hindlimb muscles has been reported in the cat but few studies have been done in non-human primates.

Forelimb muscle representations and output properties of motor areas in the mesial wall of rhesus macaques.

In this study, forelimb organizations and output properties of the supplementary motor area (SMA) and the dorsal cingulate motor area (CMAd) were assessed and compared with primary motor cortex (M1). Stimulus-triggered averages of electromyographic activity from 24 muscles of the forelimb were computed from layer V sites of 2 rhesus monkeys performing a reach-to-grasp task. No clear segregation of the forelimb representation of proximal and distal muscles was found in SMA.