A novel rat robot controlled by electrical stimulation of the nigrostriatal pathway.

OBJECTIVE: Artificial manipulation of animal movement could offer interesting advantages and potential applications using the animal's inherited superior sensation and mobility. Although several behavior control models have been introduced, they generally epitomize virtual reward-based training models. In this model, rats are trained multiple times so they can recall the relationship between cues and rewards. It is well known that activation of one side of the nigrostriatal pathway (NSP) in the rat induces immediate turning toward the contralateral side. However, this NSP stimulation-induced directional movement has not been used for the purpose of animal-robot navigation. In this study, the authors aimed to electrically stimulate the NSP of conscious rats to build a command-prompt rat robot. METHODS: Repetitive NSP stimulation at 1-second intervals was applied via implanted electrodes to induce immediate contraversive turning movements in 7 rats in open field tests in the absence of any sensory cues or rewards. The rats were manipulated to navigate from the start arm to a target zone in either the left or right arm of a T-maze. A leftward trial was followed by a rightward trial, and each rat completed a total of 10 trials. In the control group, 7 rats were tested in the same way without NSP stimulation. The time taken to navigate the maze was compared between experimental and control groups. RESULTS: All rats in the experimental group successfully reached the target area for all 70 trials in a short period of time with a short interstimulus interval (< 0.7 seconds), but only 41% of rats in the control group reached the target area and required a longer period of time to do so. The experimental group made correct directional turning movements at the intersection zone of the T-maze, taking significantly less time than the control group. No significant difference in navigation duration for the forward movements on the start and goal arms was observed between the two groups. However, the experimental group showed quick and accurate movement at the intersection zone, which made the difference in the success rate and elapsed time of tasks. CONCLUSIONS: The results of this study clearly indicate that a rat-robot model based on NSP stimulation can be a practical alternative to previously reported models controlled by virtual sensory cues and rewards.

Dual closed-loop sliding mode control for a decoupled three-link wheeled mobile manipulator.

This paper presents a dual closed-loop sliding mode control strategy for a wheeled mobile manipulator with three-wheeled mobile platform (WMP) and three-link manipulator. The Euler-Lagrange method combined partially with the Newtonian method is applied to obtain full dynamic model and decoupled model is constructed in order to provide simple dynamic model for controller's structure to be simplified. Instead of the conventional velocity command trajectory based kinematic backstepping control method, a dual closed-loop control system is designed. A virtual velocity command based on sliding mode surface is generated in outer loop and the gap between a generated virtual command velocity and real velocity is compensated by an inner loop sliding mode controller. Outer loop helps to faster posture trajectory generation for locomotion of the WMP. Next, a finite-time sliding mode controller with an assumed feedforward dynamic gain method is designed for joint trajectory tracking for three-link manipulator by adding finite-time control terms in the designed controllers to obtain faster settling time and stronger robustness. The designed controllers were implemented into microprocessor connected to DC and dynamixel motor systems equipped in mobile platform and manipulator, respectively. Comparative simulation and experiment with a conventional sliding mode control show the effectiveness of the proposed dual closed-loop finite time sliding mode control scheme.

Cross detection for odor of metabolic waste between breast and colorectal cancer using canine olfaction.

Although several studies have been performed to detect cancer using canine olfaction, none have investigated whether canine olfaction trained to the specific odor of one cancer is able to detect odor related to other unfamiliar cancers. To resolve this issue, we employed breast and colorectal cancer in vitro, and investigated whether trained dogs to odor related to metabolic waste from breast cancer are able to detect it from colorectal cancer, and vice versa. The culture liquid samples used in the cultivation of cancerous cells (4T1 and CT26) were employed as an experimental group. Two different breeds of dogs were trained for the different cancer odor each other. The dogs were then tested using a double-blind method and cross-test to determine whether they could correctly detect the experimental group, which contains the specific odor for metabolic waste of familiar or unfamiliar cancer. For two cancers, both dogs regardless of whether training or non-training showed that accuracy was over 90%, and sensitivity and specificity were over 0.9, respectively. Through these results, it was verified that the superior olfactory ability of dogs can discriminate odor for metabolic waste of cancer cells from it of benign cells, and that the specific odor for metabolic waste of breast cancer has not significant differences to it of colorectal cancer. That is, it testifies that metabolic waste between breast and colorectal cancer have the common specific odor in vitro. Accordingly, a trained dogs for detecting odor for metabolic waste of breast cancer can perceive it of colorectal cancer, and vice versa. In order to the future work, we will plan in vivo experiment for the two cancers and suggest research as to what kind of cancers have the common specific odor. Furthermore, the relationship between breast and colorectal cancer should be investigated using other research methods.

Decoding intravesical pressure from local field potentials in rat lumbosacral spinal cord.

Chronic monitoring of intravesical pressure is required to detect the onset of intravesical hypertension and the progression of a more severe condition. Recent reports demonstrate the bladder state can be monitored from the spiking activity of the dorsal root ganglia or lumbosacral spinal cord. However, one of the most serious challenges for these methods is the difficulty of sustained spike signal acquisition due to the high-electrode-location-sensitivity of spikes or neuro-degeneration. Alternatively, it has been demonstrated that local field potential recordings are less affected by encapsulation reactions or electrode location changes. Here, we hypothesized that local field potential (LFP) from the lumbosacral dorsal horn may provide information concerning the intravesical pressure. LFP and spike activities were simultaneously recorded from the lumbosacral spinal cord of anesthetized rats during bladder filling. The results show that the LFP activities carry significant information about intravesical pressure along with spiking activities. Importantly, the intravesical pressure is decoded from the power in high-frequency bands (83.9-256 Hz) with a substantial performance similar to that of the spike train decoding. These findings demonstrate that high-frequency LFP activity can be an alternative intravesical pressure monitoring signal, which could lead to a proper closed loop system for urinary control.

Detecting bladder fullness through the ensemble activity patterns of the spinal cord unit population in a somatovisceral convergence environment.

OBJECTIVE: Chronic monitoring of the state of the bladder can be used to notify patients with urinary dysfunction when the bladder should be voided. Given that many spinal neurons respond both to somatic and visceral inputs, it is necessary to extract bladder information selectively from the spinal cord. Here, we hypothesize that sensory information with distinct modalities should be represented by the distinct ensemble activity patterns within the neuronal population and, therefore, analyzing the activity patterns of the neuronal population could distinguish bladder fullness from somatic stimuli. APPROACH: We simultaneously recorded 26-27 single unit activities in response to bladder distension or tactile stimuli in the dorsal spinal cord of each Sprague-Dawley rat. In order to discriminate between bladder fullness and tactile stimulus inputs, we analyzed the ensemble activity patterns of the entire neuronal population. A support vector machine (SVM) was employed as a classifier, and discrimination performance was measured by k-fold cross-validation tests. MAIN RESULTS: Most of the units responding to bladder fullness also responded to the tactile stimuli (88.9-100%). The SVM classifier precisely distinguished the bladder fullness from the somatic input (100%), indicating that the ensemble activity patterns of the unit population in the spinal cord are distinct enough to identify the current input modality. Moreover, our ensemble activity pattern-based classifier showed high robustness against random losses of signals. SIGNIFICANCE: This study is the first to demonstrate that the two main issues of electroneurographic monitoring of bladder fullness, low signals and selectiveness, can be solved by an ensemble activity pattern-based approach, improving the feasibility of chronic monitoring of bladder fullness by neural recording.

Clinical characteristics of the causes of plantar heel pain.

OBJECTIVE: The objectives of this study were to investigate the causes of plantar heel pain and find differences in the clinical features of plantar fasciitis (PF) and fat pad atrophy (FPA), which are common causes of plantar heel pain, for use in differential diagnosis. METHOD: This retrospective study analyzed the medical records of 250 patients with plantar heel pain at the Foot Clinic of Rehabilitation Medicine at Bundang Jesaeng General Hospital from January to September, 2008. RESULTS: The subjects used in this study were 114 men and 136 women patients with a mean age of 43.8 years and mean heel pain duration of 13.3 months. Causes of plantar heel pain were PF (53.2%), FPA (14.8%), pes cavus (10.4%), PF with FPA (9.2%), pes planus (4.8%), plantar fibromatosis (4.4%), plantar fascia rupture (1.6%), neuropathy (0.8%), and small shoe syndrome (0.8%). PF and FPA were most frequently diagnosed. First-step pain in the morning, and tenderness on medial calcaneal tuberosity correlated with PF. FPA mainly involved bilateral pain, pain at night, and pain that was aggravated by standing. Heel cord tightness was the most common biomechanical abnormality of the foot. Heel spur was frequently seen in X-rays of patients with PF. CONCLUSION: Plantar heel pain can be provoked by PF, FPA, and other causes. Patients with PF or FPA typically show different characteristics in clinical features. Plantar heel pain requires differential diagnosis for appropriate treatment.

Odor-Dependent Hemodynamic Responses Measured with NIRS in the Main Olfactory Bulb of Anesthetized Rats.

In this study, we characterize the hemodynamic changes in the main olfactory bulb of anesthetized Sprague-Dawley (SD) rats with near-infrared spectroscopy (NIRS, ISS Imagent) during presentation of two different odorants. Odorants were presented for 10 seconds with clean air via an automatic odor stimulator. Odorants are: (i) plain air as a reference (Blank), (ii) 2-Heptanone (HEP), (iii) Isopropylbenzene (IB). Our results indicated that a plain air did not cause any change in the concentrations of oxygenated (Δ[HbO(2)]) and deoxygenated hemoglobin (Δ[Hbr]), but HEP and IB induced strong changes. Furthermore, these odor-specific changes had regional differences within the MOB. Our results suggest that NIRS technology might be a useful tool to identify of various odorants in a non-invasive manner using animals which has a superb olfactory system.