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Bipedal (Bp) locomotion is one of the most characteristic motor behaviors in human beings. Innate quadrupedal (Qp) four-legged animals also often walk bipedally. The walking posture, however, is significantly different between the two. This suggests that although both have a potential to walk bipedally, however, the human has a body scheme suitable for Bp locomotion, probably its skeletal system. The skeletal system includes the lumbar lordosis, sacral kyphosis, a round pelvis, a large femur neck angle, short feet, and so on. To verify this hypothesis, we compared kinematic and EMG activities between rats and humans during Qp and Bp locomotion on a treadmill belt. The rat is a representative Qp animal, but it is able to acquire Bp walking capability with motor learning. Although the mobile ranges of the hindlimb joint are different during each locomotor pattern between rats and humans, both showed replicable flexion and extension excursion patterns for each joint depending on the locomotor phase. There are many phase-locked EMG bursts between rats and humans during the same walking task and these are observed in the proximal rather than the distal muscles. This suggests that both rats and humans utilize similar neuronal systems for the elaboration of Qp and Bp locomotion. It was interesting that both subjects showed more muscle activities during non-natural locomotor patterns; Qp < Bp for rats and Bp < Qp for humans. This indicates that rat Bp and human Qp walking need more effort and we may be able to find its reason in their skeletal system.

ABSTRACT. We studied the reflex actions of the cutaneous afferents innervating the trunk to hindlimb motoneurons in the spinal cat using an intracellular recording technique. Stimulation of the trunk cutaneous afferents entering into the L2-L5 spinal segment produced different types of polysynaptic potentials in hindlimb motoneurons via polysynaptic neuronal pathways. The trunk cutaneous afferents predominantly caused excitatory PSPs in the flexor motoneurons and inhibitory PSPs in the extensor motoneurons. The size and latency of polysynaptic potentials were related to the proximity of the spinal segments of the nerves stimulated to the spinal segments of motoneurons. These findings suggest that the neuronal pathways from trunk cutaneous afferents to hindlimb motoneurons play an important role in coordinating between the trunk and hindlimbs. The trunk represents a large part of the body mass and constitutes an integral part of the motor system. Study of neuronal control of trunk movements and posture is very important to understand body balance. Trunk movements are controlled by trunk muscle activities [2,3,5,8]. We previously reported that the motoneurons innervating the erector spine muscles are strongly influenced by stimulation of the muscle and cutaneous afferent nerves innervating the trunk, limbs and tail [6,7,9,10]. These facts indicate the convergence of peripheral afferent inputs from various parts on motoneurons of the trunk muscles. Studies of how the afferent inputs from the trunk influence limb muscle activities are very important to understanding body balance. In the present experiments, we studied the effects of stimulation of the cutaneous afferent from trunk to hindlimb motoneurons.Experiments were performed on 27 adult cats (BW: 2.0-4.2 kg) of either sex in accordance with the Yamaguchi University guide for the care and use laboratory animals. Under anesthesia with halothane-nitrous oxide, the animals were decerebrated by passing a spatula rostroventrally from a line approximately 1 mm rostral to the superior colliculus and removing the tissue rostral to the transection. Anesthesia was then discontinued, and the animals were further spinalized at the T10 spinal segment. The cutaneous nerves innervating the dorsal (DC) and ventral part of the trunk (VC) originated from the dorsal and ventral branches of nn. lumbales. DC and VC entering into the L2-L5 spinal segment on both sides were isolated from the surrounding tissue and mounted into cuff bipolar electrodes. Furthermore, the nerves innervating the anterior part of the biceps femoris and semimenbranosus (ABSm), posterior biceps and semitendinosus (PBSt) and medial and lateral gastrocnemius (GS) were isolated and mounted on bipolar stimulating electrodes. A laminectomy was preformed between L1 and L5. The animals were fixed in stereotaxic frames, paralyzed with pancuronium bromide (0.4 mg/kg/hr) and artificially ventilated. The end-tidal CO 2 concentration was monitored and maintained at 4.0% by adjusting the respiratory rate. The rectal temp...

Background Feline leukemia virus (FeLV) is a retrovirus with global impact on the health of domestic cats and is usually examined by serology. In our daily clinical practice, we noticed that cats infected with FeLV often possess wavy whiskers (sinus hairs on the face). To investigate the relationship between wavy whiskers (WW) and FeLV infection, the association between the presence or absence of wavy changes in whiskers and serological FeLV infection was examined in a total of 358 cats including 56 cats possessing WW, using the chi-square test. The results of blood tests from 223 cases were subjected to multivariate analysis (logistic analysis). Isolated whiskers were observed under light microscopy, and upper lip tissues (proboscis) were subjected to histopathological and immunohistochemical analyses. Results The prevalence of WW was significantly correlated with FeLV antigen positivity in the blood. Of 56 cases with WW, 50 (89.3%) were serologically positive for FeLV. The significant association between WW and serological FeLV positivity was also confirmed by multivariate analysis. In WW, narrowing, degeneration, and tearing of the hair medulla were observed. Mild infiltration of mononuclear cells in the tissues, but no degeneration or necrosis, was found. By immunohistochemistry, FeLV antigens (p27, gp70 and p15E) were observed in various epithelial cells including the sinus hair follicular epithelium of the whisker. Conclusions The data suggest that the wavy changes in whiskers, a unique and distinctive external sign on a cat’s face, were associated with FeLV infection.