Phasic dopamine signals are reduced in the spontaneously hypertensive rat and increased by methylphenidate.

The spontaneously hypertensive rat (SHR) is a selectively bred animal strain that is frequently used to model attention-deficit hyperactivity disorder (ADHD) because of certain genetically determined behavioural characteristics. To test the hypothesis that the characteristically altered response to positive reinforcement in SHRs may be due to altered phasic dopamine response to reward, we measured phasic dopamine signals in the SHRs and Sprague Dawley (SD) rats using in vivo fast-scan cyclic voltammetry. The effects of the dopamine reuptake inhibitor, methylphenidate, on these signals were also studied. Phasic dopamine signals during the pairing of a sensory cue with electrical stimulation of midbrain dopamine neurons were significantly smaller in the SHRs than in the SD rats. Over repeated pairings, the dopamine response to the sensory cue increased, whereas the response to the electrical stimulation of dopamine neurons decreased, similarly in both strains. However, the final amplitude of the response to the sensory cue after pairing was significantly smaller in SHRs than in the SD rats. Methylphenidate increased responses to sensory cues to a significantly greater extent in the SHRs than in the SD rats, due largely to differences in the low dose effect. At a higher dose, methylphenidate increased responses to sensory cues and electrical stimulation similarly in SHRs and SD rats. The smaller dopamine responses may explain the reduced salience of reward-predicting cues previously reported in the SHR, whereas the action of methylphenidate on the cue response suggests a potential mechanism for the therapeutic effects of low-dose methylphenidate in ADHD.

An Improved Sensing Method of a Robotic Ultrasound System for Real-Time Force and Angle Calibration.

An ultrasonic examination is a clinically universal and safe examination method, and with the development of telemedicine and precision medicine, the robotic ultrasound system (RUS) integrated with a robotic arm and ultrasound imaging system receives increasing attention. As the RUS requires precision and reproducibility, it is important to monitor the real-time calibration of the RUS during examination, especially the angle of the probe for image detection and its force on the surface. Additionally, to speed up the integration of the RUS and the current medical ultrasound system (US), the current RUSs mostly use a self-designed fixture to connect the probe to the arm. If the fixture has inconsistencies, it may cause an operating error. In order to improve its resilience, this study proposed an improved sensing method for real-time force and angle calibration. Based on multichannel pressure sensors, an inertial measurement unit (IMU), and a novel sensing structure, the ultrasonic probe and robotic arm could be simply and rapidly combined, which rendered real-time force and angle calibration at a low cost. The experimental results show that the average success rate of the downforce position identification achieved was 88.2%. The phantom experiment indicated that the method could assist the RUS in the real-time calibration of both force and angle during an examination.

Enhancement of PVDF Sensing Characteristics by Retooling the Near-Field Direct-Write Electrospinning System.

This research aimed to develop a direct-write near-field electrospinning system (DW-NFES) with three-axis positioning of controllable speed, torque and position to produce sizable and high-quality piezoelectric fibers for sensing purposes. Sensor devices with high electrical response signals were developed and tested. To achieve DW-NFES purpose, a servo motor controller was designed to develop a high response rate, accurate positioning, and stable mobile device through the calculation of bandwidth and system time delay. With this retooled system of DW-NFES, controllable and uniform size fibers in terms of diameters, stretching force, and interspaces can be obtained. Sensor devices can be made selectively without a complicated lithography process. The characteristics of this DW-NFES platform were featured by high response rate, accurate positioning, and stable movement to make fibers with high piezoelectric property. In this study, polyvinylidene fluoride (PVDF) was used to explore and enhance their sensing quality through the platform. The parametric study of the process factors on piezoelectric sensing signals mainly included the concentration of electrospinning PVDF solution, high voltage electric field, and collection speed. Finally, the surface morphology and piezoelectric properties of the as-electrospun PVDF fibers were examined by scanning electron microscopy (SEM) and characterized by electrical response measurement techniques. The results showed that the fiber spinning speed of the DW-NFES system could be increased to ~125 from ~20 mm/s and the accuracy precision was improved to ~1 from ~50 µm, compared to conventional step motor system. The fiber diameter reached ~10 µm, and the electrospinning pitch reached to as small as ~10 µm. The piezoelectric output voltage of the electrospun fibers was increased ~28.6% from ~97.2 to ~125 mV; the current was increased ~27.6% from ~163 to ~208 nA, suggesting that the piezoelectric signals can be enhanced significantly by using this retooled system. Finally, an external control module (Arduino-MAGE) was introduced to control the PVDF piezoelectric fiber sensors integrated as a sensing array. The behavior of long-term sedentary patients can be successfully detected by this module system to prevent the patients from the bedsores.

Distinct Somatic Discrimination Reflected by Laser-Evoked Potentials Using Scalp EEG Leads.

Discrimination is an important function in pain processing of the somatic cortex. The involvement of the somatic cortex has been studied using equivalent dipole analysis and neuroimaging, but the results are inconsistent. Scalp electroencephalography (EEG) can reflect functional changes of particular brain regions underneath a lead. However, the responses of EEG leads close to the somatic cortex in response to pain have not been systematically evaluated. The present study applied CO2 laser stimulation to the dorsum of the left hand. Laser-evoked potentials (LEPs) of C4, T3, and T4 leads and pain ratings in response to four stimulus intensities were analyzed. LEPs started earlier at the C4 and T4 leads. The onset latency and peak latency of LEPs for C4 and T4 leads were the same. Only 10 of 22 subjects (45 %) presented equivalent current dipoles within the primary somatosensory or motor cortices. LEP amplitudes of these leads increased as stimulation intensity increased. The stimulus-response pattern of the C4 lead was highly correlated with pain rating. In contrast, an S-shaped stimulus-response curve was obtained for the T3 and T4 leads. The present study provides supporting evidence that particular scalp channels are able to reflect the functional characteristics of their underlying cortical areas. Our data strengthen the clinical application of somatic-cortex-related leads for pain discrimination.

The effect of tenocyte/hyaluronic acid therapy on the early recovery of healing Achilles tendon in rats.

The aim of this study was to explore the potential for a better recovery outcome for the Achilles tendon at an early healing stage when a mixed biomaterial-tenocyte injection is used. The experimental animals underwent single limb Achilles tendon transection followed by suturing repair. A solution of either hyaluronic acid with or without tenocytes or normal saline was randomly chosen to be injected around the injury site after surgery. To obtain the comprehensive recovery condition of the rats on different management protocols, the animals were evaluated histologically, mechanically, and functionally. A significant difference in the recovery condition was found in the injured tendon injected with the hyaluronic acid solution with tenocytes compared with the other groups. Tendon stiffness and the locomotion abilities of the rats with healing Achilles tendons were improved in the hyaluronic acid with tenocyte transplantation group. The acceleration of the inflammatory phase in rats with the hyaluronic acid with tenocyte injections might be the major reason for the better functional outcomes.

Sexually dimorphic urethral activity in response to pharmacological activation of 5-HT1A receptors in the rat.

In this study, we examined the possibility that 5-HT1A receptors may underlie sexually dimorphic mechanisms affecting the regulation of urethral functions in anesthetized rats. Simultaneous recordings of intravesical pressure under isovolumetric conditions, external urethral sphincter-electromyography, and urethral perfusion pressure were used to examine the effects of a 5-HT1A receptor agonist [8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT)] and antagonist (WAY-100635) on bladder and urethral functions. This research also evaluated the effects of 8-OH-DPAT and α-bungarotoxin (a neuromuscular blockade agent) on urethral continence using leak point pressure testing, and the distribution of 5-HT1A receptors in the lower urinary tract was assessed by immunohistochemistry. The serotonergic mechanism that controls the urinary bladder and external urethral sphincter-electromyography activity showed no significant sexual differences, but urethral activity in urethral perfusion pressure and leak point pressure values exhibited some sexual differences. 8-OH-DPAT enhanced urethral pressure during continence in rats of both sexes, but the drug elevated the pressure during voiding in male rats and reduced it in female rats. The distribution of 5-HT1A receptors in the spinal cord also showed some sexual differences. The present study contributes to our understanding of the role of 5-HT1A receptors in physiological and immunohistochemical properties of urethral smooth muscle in rats of different sexes. These findings may be a basis for the future development of pharmacotherapies for stress urinary incontinence in men.

The cortical control of cycling exercise in stroke patients: an fNIRS study.

Stroke survivors suffering from deficits in motor control typically have limited functional abilities, which could result in poor quality of life. Cycling exercise is a common training paradigm for restoring locomotion rhythm in patients. The provision of speed feedback has been used to facilitate the learning of controlled cycling performance and the neuromuscular control of the affected leg. However, the central mechanism for motor relearning of active and passive pedaling motions in stroke patients has not been investigated as extensively. The aim of this study was to measure the cortical activation patterns during active cycling with and without speed feedback and during power-assisted (passive) cycling in stroke patients. A frequency-domain near-infrared spectroscopy (FD-NIRS) system was used to detect the hemodynamic changes resulting from neuronal activity during the pedaling exercise from the bilateral sensorimotor cortices (SMCs), supplementary motor areas (SMAs), and premotor cortices (PMCs). The variation in cycling speed and the level of symmetry of muscle activation of bilateral rectus femoris were used to evaluate cycling performance. The results showed that passive cycling had a similar cortical activation pattern to that observed during active cycling without feedback but with a smaller intensity of the SMC of the unaffected hemisphere. Enhanced PMC activation of the unaffected side with improved cycling performance was observed during active cycling with feedback, with respect to that observed without feedback. This suggests that the speed feedback enhanced the PMC activation and improved cycling performance in stroke patients.

Impedimetric monitoring of IGF-1 protection of in vitro cortical neurons under ischemic conditions.

Microelectrode arrays (MEAs) incorporated with the electric cell substrate impedance sensing (ECIS) technique provide a method for acquiring cellular electrophysiological information, which is useful for the time-course monitoring of cellular outgrowth and damage. This research utilizes the ECIS technique for monitoring the time-course impedimetric changes in normal and insulin-like growth factor 1 (IGF-1)-protected cortical neurons under the ischemic insult of oxygen glucose deprivation (OGD) created in a microperfusion environment. The neuronal apoptosis is reflected by the relatively low cell viability (28 ± 11.5 %) after 30-min OGD followed by 24 h of re-oxygenation. Also the hyperpolarization phase of mitochondrial membrane potential (MMP) occurs during 2 h of the re-oxygenation period. In contrast, cortical neurons treated with 50 and 100 ng/mL IGF-1 show higher survival rates of 45 ± 5.2 % and 49 ± 9.2 %, respectively, and no occurrence of the hyperpolarization of MMP during the re-oxygenation period. The ECIS results demonstrate that the measured impedance of cortical neurons decreased from 826 ± 86 kΩ to 224 ± 32 kΩ due to cell detachment under the insult of OGD. The measured impedance of IGF-1-protected cortical neurons slowly decreased to about 50 % of the original value (560 ± 45 kΩ for 50 ng/mL and 593 ± 44 kΩ for 100 ng/mL) compared to saline control of 232 ± 37 kΩ, which indicates improved cell adhesion under OGD conditions. The time-course impedimetric results show that the proposed ECIS-based MEAs platform incorporated with a microperfusion environment can be used for the real-time monitoring of cortical neurons under in vitro OGD and the IGF-1 protective effect against OGD-induced ischemic neuronal death.

Microelectrodes with gold nanoparticles and self-assembled monolayers for in vivo recording of striatal dopamine.

Electrochemical determination of in vivo dopamine (DA) using implantable microelectrodes is essential for monitoring the DA depletion of an animal model of Parkinson's disease (PD), but faces substantial interference from ascorbic acid (AA) in the brain area due to similar electroactive characteristics. This study utilizes gold nanoparticles (Au-NPs) and self-assembled monolayers (SAMs) to modify platinum microelectrodes for improving sensitivity and specificity to DA and alleviating AA interference. With appropriate choice of ω-mercaptoalkane carboxylic acid chain length, our results show that a platinum microelectrode coated with Au-NPs and 3-mercaptopropionic acid (MPA) has approximately an 881-fold specificity to AA. During amperometric measurements, Au-NP/MPA reveals that the responsive current is linearly dependent on DA over the range of 0.01-5 µM with a correlation coefficient of 0.99 and the sensitivity is 2.7-fold that of a conventional Nafion-coated electrode. Other important features observed include fast response time (below 2 s), resistance to albumin adhesion and low detection limit (7 nM) at a signal to noise ratio of 3. Feasibility of in vivo DA recording with the modified microelectrodes is verified by real-time monitoring of electrically stimulated DA release in the striatum of anesthetized rats with various stimulation parameters and administration of a DA uptake inhibitor. The developed microelectrodes present an attractive alternative to the traditional options for continuous electrochemical in vivo DA monitoring.

Evaluating interhemispheric synchronization and cortical activity in acute stroke patients using optical hemodynamic oscillations.

Objective.An understanding of functional interhemispheric asymmetry in ischemic stroke patients is a crucial factor in the designs of efficient programs for post-stroke rehabilitation. This study evaluates interhemispheric synchronization and cortical activities in acute stroke patients with various degrees of severity and at different post-stroke stages.Approach.Twenty-three patients were recruited to participate in the experiments, including resting-state and speed finger-tapping tasks at week-1 and week-3 post-stroke. Multichannel near-infrared spectroscopy (NIRS) was used to measure the changes in hemodynamics in the bilateral prefrontal cortex (PFC), the supplementary motor area (SMA), and the sensorimotor cortex (SMC). The interhemispheric correlation coefficient (IHCC) measuring the synchronized activities in time and the wavelet phase coherence (WPCO) measuring the phasic activity in time-frequency were used to reflect the symmetry between the two hemispheres within a region. The changes in oxyhemoglobin during the finger-tapping tasks were used to present cortical activation.Main results.IHCC and WPCO values in the severe-stroke were significantly lower than those in the minor-stroke at low frequency bands during week-3 post-stroke. Cortical activation in all regions in the affected hemisphere was significantly lower than that in the unaffected hemisphere in the moderate-severe stroke measured in week-1, however, the SMC activation on the affected hemisphere was significantly enhanced in week-3 post-stroke.Significance.In this study, non-invasive NIRS was used to observe dynamic synchronization in the resting-state based on the IHCC and WPCO results as well as hemodynamic changes in a motor task in acute stroke patients. The findings suggest that NIRS could be used as a tool for early stroke assessment and evaluation of the efficacy of post-stroke rehabilitation.

Effect of a 5-HT1A receptor agonist (8-OH-DPAT) on external urethral sphincter activity in a rat model of pudendal nerve injury.

Although serotonergic agents have been used to treat patients with stress urinary incontinence, the characteristics of the external urethral sphincter (EUS) activity activated by 5-HT receptors have not been extensively studied. This study examined the effects of the 5-HT(1A) receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), on the EUS-electromyography and resistance of the urethra in a rat model with bilateral pudendal nerve injury (BPNI). Two measurements were utilized to assess the effects of the drug on bladder and urethral functions: the simultaneous recordings of transvesical pressure under isovolumetric conditions [isovolumetric intravesical pressure (IVP)] and urethral perfusion pressure, and the simultaneous recordings of IVP during continuously isotonic transvesical infusion with an open urethra (isotonic IVP) and EUS-electromyography. This study also evaluated the urethral continence using leak point pressure testing. The urethral perfusion pressure and leak point pressure measurements of BPNI rats reveal that 8-OH-DPAT significantly increased urethral resistance during the bladder storage phase, yet decreased resistance during the voiding phase. The entire EUS burst period was significantly prolonged, within which the average silent period increased and the frequency of burst discharges decreased. 8-OH-DPAT also improved the voiding efficiency, as evidenced by the detection of decreases in the contraction amplitude and residual volume, with increases in contraction duration and voided volume. These findings suggest that 8-OH-DPAT not only improved continence function, but also elevated the voiding function in a BPNI rat model.

Designing and pilot testing a novel high-definition transcranial burst electrostimulation device for neurorehabilitation.

Objective.Non-invasive brain stimulation has been promoted to facilitate neuromodulation in treating neurological diseases. Recently, high-definition (HD) transcranial electrical stimulation and a novel electrical waveform combining a direct current (DC) and theta burst stimulation (TBS)-like protocol were proposed and demonstrated high potential to enhance neuroplastic effects in a more-efficient manner. In this study, we designed a novel HD transcranial burst electrostimulation device and to preliminarily examined its therapeutic potential in neurorehabilitation.Approach.A prototype of the transcranial burst electrostimulation device was developed, which can flexibly output a waveform that combined a DC and TBS-like protocol and can equally distribute the current into 4 × 1 HD electrical stimulation by automatic impedance adjustments. The safety and accuracy of the device were then validated in a series ofin vitroexperiments. Finally, a pilot clinical trial was conducted to assess its clinical safety and therapeutic potential on upper-extremity rehabilitation in six patients with chronic stroke, where patients received either active or sham HD transcranial burst electrostimulation combined with occupational therapy three times per week for four weeks.Main results.The prototype was tested, and it was found to comply with all safety requirements. The output parameters were accurate and met the clinical study needs. The pilot clinical study demonstrated that the active HD transcranial burst electrostimulation group had greater improvement in voluntary motor function and coordination of the upper extremity than the sham control group. Additionally, no severe adverse events were noted, but slight skin redness under the stimulus electrode immediately after stimulation was seen.Conclusions.The results demonstrated the feasibility of incorporating the HD electrical DC and TBS-like protocol in our device; and the novel neuromodulatory device produced positive neurorehabilitation outcomes in a safe fashion, which could be the basis for the future clinical implementation for treating neurological diseases.Trial registration:ClinicalTrials.gov Identifier: NCT04278105. Registered on 20 February 2020.

Measurement of intrinsic optical backscattering characteristics of cells using fiber-guided near infrared light.

BACKGROUND: Intrinsic optical signals (IOS), which reflect changes in transmittance and scattering light, have been applied to characterize the physiological conditions of target biological tissues. Backscattering approaches allow mounting of the source and detector on the same side of a sample which creates a more compact physical layout of device. This study presents a compact backscattering design using fiber-optic guided near-infrared (NIR) light to measure the amplitude and phase changes of IOS under different osmotic challenges. METHODS: High-frequency intensity-modulated light was guided via optic fiber, which was controlled by micromanipulator to closely aim at a minimum cluster of cortical neurons. Several factors including the probe design, wavelength selection, optimal measuring distance between the fiber-optical probe and cells were considered. Our experimental setup was tested in cultured cells to observe the relationship between the changes in backscattered NIR light and cellular IOS, which is believed mainly caused by cell volume changes in hypo/hyperosmotic solutions (+/- 20, +/- 40 and +/- 60 mOsm). RESULTS: The critical parameters of the current setup including the optimal measuring distance from fiber-optical probe to target tissue and the linear relationship between backscattering intensity and cell volume were determined. The backscattering intensity was found to be inversely proportional to osmotic changes. However, the phase shift exhibited a nonlinear feature and reached a plateau at hyperosmotic solution. CONCLUSIONS: Our study indicated that the backscattering NIR light guided by fiber-optical probe makes it a potential alternative for continuous observation of intrinsic optical properties of cell culture under varied physical or chemical challenges.

Impaired regulation function in cardiovascular neurons of nucleus tractus solitarii in streptozotocin-induced diabetic rats.

This study characterizes neural firing activity of the nucleus tractus solitarii (NTS) and baroreflex sensitivity (BRS) in streptozotocin (STZ)-induced diabetic rats relative to control rats by implantation of multi-wire electrode into rat NTS for direct monitoring of barosensitive NTS neurons before and after baroreflex system challenge by phenylephrine (PE) injection. NTS firing data is correlated with arterial pressure for both control and diabetic rats. In control rats, NTS firing rate and systolic arterial pressure correlate significantly with both pre-PE (baseline) and post-PE (p<0.01). In STZ-induced diabetic rats, positive correlation is observed only after PE injection (p<0.05). Although NTS firing rate was not significantly different between control and diabetic rats (p=0.085) in the baseline condition, it was significantly reduced in STZ-induced diabetic rats (p=0.042) with adjustment for BRS. After PE injection, NTS firing rate is significantly lower in diabetic rats relative to control rats (p<0.01). With adjustment for BRS, multivariate analysis shows that diabetes is independently associated with NTS firing rate after PE injection (p=0.034). Prior physiological and immunofluorescent studies found differing NTS data for control and diabetic rat only after PE challenge, but our data show diabetes-induced barosensitive NTS impairment in the baseline condition for STZ-induced diabetic rats. This latter finding suggests greater sensitivity of multi-wire electrode study of NTS relative to earlier methods.

Improved bladder emptying in urinary retention by electrical stimulation of pudendal afferents.

Urinary retention is the inability to empty the bladder completely, and may result from bladder hypocontractility, increases in outlet resistance or both. Chronic urinary retention can lead to several urological complications and is often refractory to pharmacologic, behavioral and surgical treatments. We sought to determine whether electrical stimulation of sensory fibers in the pudendal nerve could engage an augmenting reflex and thereby improve bladder emptying in an animal model of urinary retention. We measured the efficiency of bladder emptying with and without concomitant electrical stimulation of pudendal nerve afferents in urethane-anesthetized rats. Voiding efficiency (VE = voided volume/initial volume) was reduced from 72 +/- 7% to 29 +/- 7% following unilateral transection of the sensory branch of the pudendal nerve (UST) and from 70 +/- 5% to 18 +/- 4% following bilateral transection (BST). Unilateral electrical stimulation of the proximal transected sensory pudendal nerve during distention-evoked voiding contractions significantly improved VE. Low-intensity stimulation at frequencies of 1-50 Hz increased VE to 40-51% following UST and to 39-49% following BST, while high-intensity stimulation was ineffective at increasing VE. The increase in VE was mediated by increases in the duration of distention-evoked voiding bladder contractions, rather than increases in contraction amplitude. These results are consistent with an essential role for pudendal sensory feedback in efficient bladder emptying, and raise the possibility that electrical activation of pudendal nerve afferents may provide a new approach to restore efficient bladder emptying in persons with urinary retention.

Time course analysis of the effects of botulinum toxin type a on elbow spasticity based on biomechanic and electromyographic parameters.

OBJECTIVE: To quantify changes of elbow spasticity over time after botulinum toxin type A (BTX-A) injection in the upper extremity of stroke patients. DESIGN: Before-after trial in which the therapeutic effects were followed up at 2, 6, and 9 weeks after the BTX-A injection (Botox). SETTING: Hospital. PARTICIPANTS: Chronic stroke patients (N=8) with upper-limb spasticity. INTERVENTION: BTX-A was injected in upper-limb muscles, including the biceps brachii. MAIN OUTCOME MEASURES: Treatment effects were quantified as the changes in the velocity and the length dependence of hyperexcitable stretch reflexes. Manual sinusoid stretches of the elbow joint at 4 frequencies (1/3, 1/2, 1, 3/2Hz) over a movement range of 60 degrees were performed on patients by using a portable device. The Modified Ashworth Scale (MAS), biomechanic viscosity, and the reflexive electromyography threshold (RET) of the biceps brachii were used to evaluate the degree of hypertonia. RESULTS: The statistical analyses of the MAS score, biomechanic viscosity, and RET revealed a significant decrease in spasticity after the injection (all P<.05). Moreover, our quantitative parameters (biomechanic viscosity, RET) revealed small changes in spasticity after the BTX-A injection that could not be observed from clinical MAS evaluations. Five of 8 subjects showed a maximal reduction in spasticity (in terms of biomechanic viscosity value) within 6 weeks after the injection, whereas it was notable that all subjects exhibited peak RET values at either 2 or 6 weeks after the injection with variable degrees of relapse of spasticity. CONCLUSIONS: Early relapse of spasticity (within 9 weeks of the injection) can be detected from biomechanic and neurophysiologic assessments in a clinical setup. These quantitative indices provide valuable information for clinicians when making decisions to perform additional rehabilitation interventions or another BTX-A injection in the early stages of treatment.

Bilateral changes in afterhyperpolarization duration of spinal motoneurones in post-stroke patients.

This paper extends the observations presented in the previously published work on the afterhyperpolarization (AHP) duration changes in motoneurones (MNs) on the paretic (more affected) side of 11 post-stroke patients by the same analysis on the non-paretic (less-affected) side. The estimated AHP duration for patients' MNs supplying more-affected muscles was significantly longer than control values and the elongation decreased with patient age and disorder duration. For MNs supplying less-affected muscles, dependency of AHP duration on age was closer to the control data, but the scatter was substantially bigger. However, the AHP duration estimate of less-affected MNs tended to be longer than that of controls in the short time elapsed since the stroke, and shorter than controls in the long time. Our results thus suggest that the spinal MNs on both sides respond to the cerebral stroke rapidly with prolongation of AHP duration, which tends to normalize with time, in line with functional recovery. This suggestion is in concert with the published research on post-stroke changes in brain hemispheres. To our knowledge, these dependencies have never been investigated before. Since the number of our data was limited, the observed trends should be verified in a larger sample of patients and such a verification could take into account the suggestions for data analysis that we provide in this paper. Our data are in line with the earlier published research on MN firing characteristics post-stroke and support the conclusion that the MUs of the muscles at the non-paretic side are also affected and cannot be considered a suitable control for the MUs on the paretic side.

Modulation of motor excitability by cortical optogenetic theta burst stimulation.

Intermittent theta burst stimulation (iTBS) and continuous theta burst stimulation (cTBS) are protocols used in repetitive transcranial magnetic stimulation (rTMS) or cortical electrical stimulation (CES) to facilitate or suppress corticospinal excitability. However, rTMS and CES excite all types of neuron in the target cortex probed by the coil or electrode, making it difficult to differentiate the effect of TBS on specific neural circuits involved in motor plasticity. In this study, TBS protocols were converted into an optogenetic model to achieve focalized and cell-type-specific cortical modulation. Light-sensitive channelrhodopsin-2 (ChR2) was expressed in the glutamatergic neuron in the primary motor cortex (M1) driven by the CaMKIIα promoter. A custom-made optrode comprising an optical fiber and a metal cannula electrode was fabricated to achieve optogenetic stimulation and simultaneous local field potential (LFP) recording. Single-pulse CES was delivered into M1 to elicit motor-evoked potential (MEP), which served as an indicator of motor excitability, before and after TBS intervention. Results show that both CES-iTBS and optogenetic iTBS (Opto-iTBS) can potentiate MEP activity. However, CES-cTBS suppressed MEP activity whereas Opto-cTBS enhanced it. This discrepancy may have resulted from the different neural networks targeted by the two TBS modalities, with CES-cTBS exciting all types of neuron and Opto-cTBS targeting excitatory neuron specifically. The results support the idea that intra-cortical networks determine the variation of TBS-induced neuroplasticity. This study shows that focalized and cell-type-specific brain stimulation using the optogenetic approach is viable and can be extended for further exploration of neuroplasticity.

Effects of functional electrical stimulation on peak torque and body composition in patients with incomplete spinal cord injury.

The aim of this study was to investigate the change in body composition, leg girths, and muscle strength of patients with incomplete spinal cord injury (SCI) after functional electrical stimulation cycling exercises (FESCE). Eighteen subjects with incomplete SCI were recruited. Each patient received FESCE three times per week for 8 weeks. Body composition, thigh and calf girths of bilateral legs, muscle strength of bilateral knee flexors and extensors were measured before and after 4 and 8 weeks of FESCE. A significant increase in bilateral thigh girth after 4 weeks of FESCE and significant increase in muscular peak torque of knee flexion and extension were found after 8 weeks of training. Besides, lean body mass increased significantly after complete treatment. FESCE can increase the thigh girth and muscular peak torque of patients with incomplete spinal cord injury.

Development of a quantitative assessment system for correlation analysis of footprint parameters to postural control in children.

It is known that neurological impairments impact postural stability, but few studies have observed the biomechanical influence of foot structure on balance. The aim of this study was to develop an integrated device for investigating the relationship between static balance and the foot structure, derived from a footprint image, under clinical tests of sensory interactions. Quantitative analysis of the footprint image acquired during balanced standing was developed as an indirect measure of the longitudinal arch, an important structural component of the foot. A data pool was collected from 64 children, 32 children from each of two age groups (4-5 years old versus 8-10 years old). Six common footprint parameters derived from the footprint angle or contact area were used to investigate the relationship between footprint parameters and postural stability. Postural balance ability was evaluated by analyzing sway area in posturography under visual or somatosensory confliction conditions. The footprint parameters, derived from the footprint image, inter-correlated well with each other (p < 0.01). The relationships between footprint parameters and sway area were correlated only for younger children under visually deprived (eye close) and cutaneous unreliable (standing on compliant foam) conditions. This implies that the correlations between footprint parameters and sway area are very subtle which can only be observed in unreliable visual and somatosensory conditions of younger children. In addition, younger children with a lower arch height would have a smaller sway area and better posture control which might result from more cutaneous somatosensation or a flexible biomechanical structure in low arch feet during conditioned static standing.