Alpha oscillations reflect similar mapping mechanisms for localizing touch on hands and tools

It has been suggested that our brain re-uses body-based computations to localize touch on tools, but the neural implementation of this process remains unclear. Neural oscillations in the alpha and beta frequency bands are known to map touch on the body in external and skin-centered coordinates, respectively. Here, we pinpointed the role of these oscillations during tool-extended sensing by delivering tactile stimuli to either participants' hands or the tips of hand-held rods. To disentangle brain responses related to each coordinate system, we had participants' hands/tool tips crossed or uncrossed at their body midline. We found that midline crossing modulated alpha (but not beta) band activity similarly for hands and tools, also involving a similar network of cortical regions. Our findings strongly suggest that the brain uses similar oscillatory mechanisms for mapping touch on the body and tools, supporting the idea that body-based neural processes are repurposed for tool use.

A Somatosensory Computation That Unifies Limbs and Tools

It is often claimed that tools are embodied by their user, but whether the brain actually repurposes its body-based computations to perform similar tasks with tools is not known. A fundamental computation for localizing touch on the body is trilateration. Here, the location of touch on a limb is computed by integrating estimates of the distance between sensory input and its boundaries (e.g., elbow and wrist of the forearm). As evidence of this computational mechanism, tactile localization on a limb is most precise near its boundaries and lowest in the middle. Here, we show that the brain repurposes trilateration to localize touch on a tool, despite large differences in initial sensory input compared with touch on the body. In a large sample of participants, we found that localizing touch on a tool produced the signature of trilateration, with highest precision close to the base and tip of the tool. A computational model of trilateration provided a good fit to the observed localization behavior. To further demonstrate the computational plausibility of repurposing trilateration, we implemented it in a three-layer neural network that was based on principles of probabilistic population coding. This network determined hit location in tool-centered coordinates by using a tool's unique pattern of vibrations when contacting an object. Simulations demonstrated the expected signature of trilateration, in line with the behavioral patterns. Our results have important implications for how trilateration may be implemented by somatosensory neural populations. We conclude that trilateration is likely a fundamental spatial computation that unifies limbs and tools.

Rapid adaptation of brain-computer interfaces to new neuronal ensembles or participants via generative modelling

For brain-computer interfaces (BCIs), obtaining sufficient training data for algorithms that map neural signals onto actions can be difficult, expensive or even impossible. Here we report the development and use of a generative model-a model that synthesizes a virtually unlimited number of new data distributions from a learned data distribution-that learns mappings between hand kinematics and the associated neural spike trains. The generative spike-train synthesizer is trained on data from one recording session with a monkey performing a reaching task and can be rapidly adapted to new sessions or monkeys by using limited additional neural data. We show that the model can be adapted to synthesize new spike trains, accelerating the training and improving the generalization of BCI decoders. The approach is fully data-driven, and hence, applicable to applications of BCIs beyond motor control.

A horizon for haptic perception

The spatial limits of sensory acquisition (its sensory horizon) is a fundamental property of any sensorimotor system. In the present study, we sought to determine whether there is a sensory horizon for the human haptic modality. At first blush, it seems obvious that the haptic system is bounded by the space where the body can interact with the environment (e.g., the arm span). However, the human somatosensory system is exquisitely tuned to sensing with tools-blind-cane navigation being a classic example of this. The horizon of haptic perception therefore extends beyond body space, but to what extent is unknown. We first used neuromechanical modelling to determine the theoretical horizon, which we pinpointed as six meters. We then used a psychophysical localization paradigm to behaviorally confirm that humans can haptically localize objects using a six-meter rod. This finding underscores the incredibly flexibility of the brain's sensorimotor representations, as they can be adapted to sense with an object many times longer than the user's own body.

Alpha Oscillations Are Involved in Localizing Touch on Handheld Tools

The sense of touch is not restricted to the body but can also extend to external objects. When we use a handheld tool to contact an object, we feel the touch on the tool and not in the hand holding the tool. The ability to perceive touch on a tool actually extends along its entire surface, allowing the user to accurately localize where it is touched similarly as they would on their body. Although the neural mechanisms underlying the ability to localize touch on the body have been largely investigated, those allowing to localize touch on a tool are still unknown. We aimed to fill this gap by recording the electroencephalography signal of participants while they localized tactile stimuli on a handheld rod. We focused on oscillatory activity in the alpha (7–14 Hz) and beta (15–30 Hz) ranges, as they have been previously linked to distinct spatial codes used to localize touch on the body. Beta activity reflects the mapping of touch in skin-based coordinates, whereas alpha activity reflects the mapping of touch in external space. We found that alpha activity was solely modulated by the location of tactile stimuli applied on a handheld rod. Source reconstruction suggested that this alpha power modulation was localized in a network of fronto-parietal regions previously implicated in higher-order tactile and spatial processing. These findings are the first to implicate alpha oscillations in tool-extended sensing and suggest an important role for processing touch in external space when localizing touch on a tool.

Simulated proximity enhances perceptual and physiological responses to emotional facial expressions

Physical proximity is important in social interactions. Here, we assessed whether simulated physical proximity modulates the perceived intensity of facial emotional expressions and their associated physiological signatures during observation or imitation of these expressions. Forty-four healthy volunteers rated intensities of dynamic angry or happy facial expressions, presented at two simulated locations, proximal (0.5 m) and distant (3 m) from the participants. We tested whether simulated physical proximity affected the spontaneous (in the observation task) and voluntary (in the imitation task) physiological responses (activity of the corrugator supercilii face muscle and pupil diameter) as well as subsequent ratings of emotional intensity. Angry expressions provoked relative activation of the corrugator supercilii muscle and pupil dilation, whereas happy expressions induced a decrease in corrugator supercilii muscle activity. In proximal condition, these responses were enhanced during both observation and imitation of the facial expressions, and were accompanied by an increase in subsequent affective ratings. In addition, individual variations in condition related EMG activation during imitation of angry expressions predicted increase in subsequent emotional ratings. In sum, our results reveal novel insights about the impact of physical proximity in the perception of emotional expressions, with early proximity-induced enhancements of physiological responses followed by an increased intensity rating of facial emotional expressions.

Online proprioception feeds plasticity of arm representation following tool-use in healthy aging

Following tool-use, the kinematics of free-hand movements are altered. This modified kinematic pattern has been taken as a behavioral hallmark of the modification induced by tool-use on the effector representation. Proprioceptive inputs appear central in updating the estimated effector state. Here we questioned whether online proprioceptive modality that is accessed in real time, or offline, memory-based, proprioception is responsible for this update. Since normal aging affects offline proprioception only, we examined a group of 60 year-old adults for proprioceptive acuity and movement's kinematics when grasping an object before and after tool-use. As a control, participants performed the same movements with a weight-equivalent to the tool-weight-attached to their wrist. Despite hampered offline proprioceptive acuity, 60 year-old participants exhibited the typical kinematic signature of tool incorporation: Namely, the latency of transport components peaks was longer and their amplitude reduced after tool-use. Instead, we observed no kinematic modifications in the control condition. In addition, online proprioception acuity correlated with tool incorporation, as indexed by the amount of kinematics changes observed after tool-use. Altogether, these findings point to the prominent role played by online proprioception in updating the body estimate for the motor control of tools.

Visual tests predict dementia risk in Parkinson disease

OBJECTIVE

To assess the role of visual measures and retinal volume to predict the risk of Parkinson disease (PD) dementia.

METHODS

In this cohort study, we collected visual, cognitive, and motor data in people with PD. Participants underwent ophthalmic examination, retinal imaging using optical coherence tomography, and visual assessment including acuity and contrast sensitivity and high-level visuoperception measures of skew tolerance and biological motion. We assessed the risk of PD dementia using a recently described algorithm that combines age at onset, sex, depression, motor scores, and baseline cognition.

RESULTS

One hundred forty-six people were included in the study (112 with PD and 34 age-matched controls). The mean disease duration was 4.1 (±2·5) years. None of these participants had dementia. Higher risk of dementia was associated with poorer performance in visual measures (acuity: ρ = 0.29, p = 0.0024; contrast sensitivity: ρ = -0.37, p < 0.0001; skew tolerance: ρ = -0.25, p = 0.0073; and biological motion: ρ = -0.26, p = 0.0054). In addition, higher risk of PD dementia was associated with thinner retinal structure in layers containing dopaminergic cells, measured as ganglion cell layer (GCL) and inner plexiform layer (IPL) thinning (ρ = -0.29, p = 0.0021; ρ = -0.33, p = 0.00044). These relationships were not seen for the retinal nerve fiber layer that does not contain dopaminergic cells and were not seen in unaffected controls.

CONCLUSION

Visual measures and retinal structure in dopaminergic layers were related to risk of PD dementia. Our findings suggest that visual measures and retinal GCL and IPL volumes may be useful to predict the risk of dementia in PD.

Somatosensory Cortex Efficiently Processes Touch Located Beyond the Body

The extent to which a tool is an extension of its user is a question that has fascinated writers and philosophers for centuries [1]. Despite two decades of research [2-7], it remains unknown how this could be instantiated at the neural level. To this aim, the present study combined behavior, electrophysiology and neuronal modeling to characterize how the human brain could treat a tool like an extended sensory "organ." As with the body, participants localize touches on a hand-held tool with near-perfect accuracy [7]. This behavior is owed to the ability of the somatosensory system to rapidly and efficiently use the tool as a tactile extension of the body. Using electroencephalography (EEG), we found that where a hand-held tool was touched was immediately coded in the neural dynamics of primary somatosensory and posterior parietal cortices of healthy participants. We found similar neural responses in a proprioceptively deafferented patient with spared touch perception, suggesting that location information is extracted from the rod's vibrational patterns. Simulations of mechanoreceptor responses [8] suggested that the speed at which these patterns are processed is highly efficient. A second EEG experiment showed that touches on the tool and arm surfaces were localized by similar stages of cortical processing. Multivariate decoding algorithms and cortical source reconstruction provided further evidence that early limb-based processes were repurposed to map touch on a tool. We propose that an elementary strategy the human brain uses to sense with tools is to recruit primary somatosensory dynamics otherwise devoted to the body.

Tool Use Modulates Somatosensory Cortical Processing in Humans

Tool use leads to plastic changes in sensorimotor body representations underlying tactile perception. The neural correlates of this tool-induced plasticity in humans have not been adequately characterized. This study used ERPs to investigate the stage of sensory processing modulated by tool use. Somatosensory evoked potentials, elicited by median nerve stimulation, were recorded before and after two forms of object interaction: tool use and hand use. Compared with baseline, tool use-but not use of the hand alone-modulated the amplitude of the P100. The P100 is a mid-latency component that indexes the construction of multisensory models of the body and has generators in secondary somatosensory and posterior parietal cortices. These results mark one of the first demonstrations of the neural correlates of tool-induced plasticity in humans and suggest that tool use modulates relatively late stages of somatosensory processing outside primary somatosensory cortex. This finding is consistent with what has been observed in tool-trained monkeys and suggests that the mechanisms underlying tool-induced plasticity have been preserved across primate evolution.

Evaluation of high-density, multi-contact nerve cuffs for activation of grasp muscles in monkeys

OBJECTIVE

The objective of this work was to evaluate whether nerve cuffs can selectively activate hand muscles for functional electrical stimulation (FES). FES typically involves identifying and implanting electrodes in many individual muscles, but nerve cuffs only require implantation at a single site around the nerve. This method is surgically more attractive. Nerve cuffs may also more effectively stimulate intrinsic hand muscles, which are difficult to implant and stimulate without spillover to adjacent muscles.

APPROACH

To evaluate its ability to selectively activate muscles, we implanted and tested the flat interface nerve electrode (FINE), which is designed to selectively stimulate peripheral nerves that innervate multiple muscles (Tyler and Durand 2002 IEEE Trans. Neural Syst. Rehabil. Eng. 10 294-303). We implanted FINEs on the nerves and bipolar intramuscular wires for recording compound muscle action potentials (CMAPs) from up to 20 muscles in each arm of six monkeys. We then collected recruitment curves while the animals were anesthetized.

MAIN RESULT

A single FINE implanted on an upper extremity nerve in the monkey can selectively activate muscles or small groups of muscles to produce multiple, independent hand functions.

SIGNIFICANCE

FINE cuffs can serve as a viable supplement to intramuscular electrodes in FES systems, where they can better activate intrinsic and extrinsic muscles with lower currents and less extensive surgery.

Assessing cognitive dysfunction in Parkinson's disease: An online tool to detect visuo-perceptual deficits

BACKGROUND

People with Parkinson's disease (PD) who develop visuo-perceptual deficits are at higher risk of dementia, but we lack tests that detect subtle visuo-perceptual deficits and can be performed by untrained personnel. Hallucinations are associated with cognitive impairment and typically involve perception of complex objects. Changes in object perception may therefore be a sensitive marker of visuo-perceptual deficits in PD.

OBJECTIVE

We developed an online platform to test visuo-perceptual function. We hypothesised that (1) visuo-perceptual deficits in PD could be detected using online tests, (2) object perception would be preferentially affected, and (3) these deficits would be caused by changes in perception rather than response bias.

METHODS

We assessed 91 people with PD and 275 controls. Performance was compared using classical frequentist statistics. We then fitted a hierarchical Bayesian signal detection theory model to a subset of tasks.

RESULTS

People with PD were worse than controls at object recognition, showing no deficits in other visuo-perceptual tests. Specifically, they were worse at identifying skewed images (P < .0001); at detecting hidden objects (P = .0039); at identifying objects in peripheral vision (P < .0001); and at detecting biological motion (P = .0065). In contrast, people with PD were not worse at mental rotation or subjective size perception. Using signal detection modelling, we found this effect was driven by change in perceptual sensitivity rather than response bias.

CONCLUSIONS

Online tests can detect visuo-perceptual deficits in people with PD, with object recognition particularly affected. Ultimately, visuo-perceptual tests may be developed to identify at-risk patients for clinical trials to slow PD dementia. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

A Pilot Study of Femoropopliteal Artery Revascularisation with a Low Dose Paclitaxel Coated Balloon: Is Predilatation Necessary?

OBJECTIVE/BACKGROUND

The objective was to compare 2 year outcomes in patients treated with or without predilatation prior to drug coated balloon (DCB) angioplasty for symptomatic femoropopliteal lesions.

METHODS

This prospective multicentre pilot study was conducted at three sites in Germany. It compared claudicants undergoing predilatation with a bare percutaneous transluminal angioplasty (PTA) balloon before DCB (predilatation group) with patients undergoing direct DCB (direct DCB group). Patients were followed for 2 years. Outcomes included late lumen loss at 6 months, and ankle brachial index (ABI), major adverse events, and primary patency at 2 years. A Clinical Events Committee and core laboratories analysed adverse events and angiographic/duplex images, respectively.

RESULTS

Between December 2011 and November 2012, 50 patients were enrolled to the predilatation group (12% total occlusions) and 28 to the direct DCB group (5% total occlusions). Follow-up compliance at the 2 year visit was 88% (n = 44) and 86% (n = 24), respectively. Late lumen loss at 6 months was lower in the direct DCB group (0.03 ± 0.68 mm vs. 0.54 ± 0.97 mm; p = .01). Major adverse events over 2 years occurred in seven (15%) patients who underwent predilatation and in five (19%) after direct DCB. Mean ABI at 2 years was 0.94 ± 0.15 after predilatation and 1.0 ± 0.12 after direct DCB. Over 2 years, primary patency (80.3% vs. 78.2%; p = .55) was not statistically different between the groups. After propensity score adjustments, 2 year findings remained unchanged.

CONCLUSION

Paclitaxel coated PTA, with or without bare predilatation, is effective over 2 years in symptomatic patients with femoropopliteal stenotic lesions. Adequately powered randomised controlled comparisons are required to confirm these preliminary results.

The recalibration of tactile perception during tool use is body-part specific

Two decades of research have demonstrated that using a tool modulates spatial representations of the body. Whether this embodiment is specific to representations of the tool-using limb or extends to representations of other body parts has received little attention. Several studies of other perceptual phenomena have found that modulations to the primary somatosensory representation of the hand transfers to the face, due in part to their close proximity in primary somatosensory cortex. In the present study, we investigated whether tool-induced recalibration of tactile perception on the hand transfers to the cheek. Participants verbally estimated the distance between two tactile points applied to either their hand or face, before and after using a hand-shaped tool. Tool use recalibrated tactile distance perception on the hand-in line with previous findings-but left perception on the cheek unchanged. This finding provides support for the idea that embodiment is body-part specific. Furthermore, it suggests that tool-induced perceptual recalibration occurs at a level of somatosensory processing, where representations of the hand and face have become functionally disentangled.

Mental body representations retain homuncular shape distortions: Evidence from Weber's illusion

Mental body representations underlying tactile perception do not accurately reflect the body's true morphology. For example, perceived tactile distance is dependent on both the body part being touched and the stimulus orientation, a phenomenon called Weber's illusion. These findings suggest the presence of size and shape distortions, respectively. However, whereas each morphological feature is typically measured in isolation, a complete morphological characterization requires the concurrent measurement of both size and shape. We did so in three experiments, manipulating both the stimulated body parts (hand; forearm) and stimulus orientation while requiring participants to make tactile distance judgments. We found that the forearm was significantly more distorted than the hand lengthwise but not widthwise. Effects of stimulus orientation are thought to reflect receptive field anisotropies in primary somatosensory cortex. The results of the present study therefore suggest that mental body representations retain homuncular shape distortions that characterize early stages of somatosensory processing.

Brain-controlled neuromuscular stimulation to drive neural plasticity and functional recovery

There is mounting evidence that appropriately timed neuromuscular stimulation can induce neural plasticity and generate functional recovery from motor disorders. This review addresses the idea that coordinating stimulation with a patient's voluntary effort might further enhance neurorehabilitation. Studies in cell cultures and behaving animals have delineated the rules underlying neural plasticity when single neurons are used as triggers. However, the rules governing more complex stimuli and larger networks are less well understood. We argue that functional recovery might be optimized if stimulation were modulated by a brain machine interface, to match the details of the patient's voluntary intent. The potential of this novel approach highlights the need for a better understanding of the complex rules underlying this form of plasticity.

Action verbs are processed differently in metaphorical and literal sentences depending on the semantic match of visual primes

Language comprehension requires rapid and flexible access to information stored in long-term memory, likely influenced by activation of rich world knowledge and by brain systems that support the processing of sensorimotor content. We hypothesized that while literal language about biological motion might rely on neurocognitive representations of biological motion specific to the details of the actions described, metaphors rely on more generic representations of motion. In a priming and self-paced reading paradigm, participants saw video clips or images of (a) an intact point-light walker or (b) a scrambled control and read sentences containing literal or metaphoric uses of biological motion verbs either closely or distantly related to the depicted action (walking). We predicted that reading times for literal and metaphorical sentences would show differential sensitivity to the match between the verb and the visual prime. In Experiment 1, we observed interactions between the prime type (walker or scrambled video) and the verb type (close or distant match) for both literal and metaphorical sentences, but with strikingly different patterns. We found no difference in the verb region of literal sentences for Close-Match verbs after walker or scrambled motion primes, but Distant-Match verbs were read more quickly following walker primes. For metaphorical sentences, the results were roughly reversed, with Distant-Match verbs being read more slowly following a walker compared to scrambled motion. In Experiment 2, we observed a similar pattern following still image primes, though critical interactions emerged later in the sentence. We interpret these findings as evidence for shared recruitment of cognitive and neural mechanisms for processing visual and verbal biological motion information. Metaphoric language using biological motion verbs may recruit neurocognitive mechanisms similar to those used in processing literal language but be represented in a less-specific way.

Enhanced mental rotation ability in time-space synesthesia

Time-space synesthesia is a variant of sequence-space synesthesia and involves the involuntary association of months of the year with 2D and 3D spatial forms, such as arcs, circles, and ellipses. Previous studies have revealed conflicting results regarding the association between time-space synesthesia and enhanced spatial processing ability. Here, we tested 15 time-space synesthetes, and 15 non-synesthetic controls matched for age, education, and gender on standard tests of mental rotation ability, spatial working memory, and verbal working memory. Synesthetes performed better than controls on our test of mental rotation, but similarly to controls on tests of spatial and verbal working memory. Results support a dissociation between visuo-spatial imagery and spatial working memory capacity, and suggest time-space synesthesia is associated only with enhanced visuo-spatial imagery. These data are consistent with the time-space connectivity thesis that time-space synesthesia results from enhanced connectivity in the parietal lobe between regions supporting the representation of temporal sequences and those underlying visuo-spatial imagery.

Impact of a resistant dextrin on intestinal ecology: how altering the digestive ecosystem with NUTRIOSE®, a soluble fibre with prebiotic properties, may be beneficial for health

OBJECTIVES

The prebiotic potential of NUTRIOSE®--a sugar-free, digestion-resistant dextrin--was evaluated in two randomized, placebo-controlled trials that included 48 and 40 healthy volunteers, respectively.

METHODS

In study 1, the effect on colonic bacteria of NUTRIOSE® 10, 15 or 20 g/day administered for 14 days was examined; in study 2, gut microbial changes in response to NUTRIOSE® 8 g/day for 14 days were monitored using real-time polymerase chain reaction analysis.

RESULTS

NUTRIOSE® increased proliferation of Bacteroides and inhibited Clostridum perfringens in both studies, increased β-glucosidase activity (at 10 and 15 g/day) and decreased colonic pH (at 20 g/day). The increase in short-chain fatty acid production with NUTRIOSE® consumption was not statistically significant. There were no indications of gastrointestinal intolerance at any dose.

CONCLUSIONS

According to commonly accepted definitions, NUTRIOSE® is a prebiotic soluble fibre that provides a beneficial effect on colonic ecology while preserving digestive comfort.

Motor cortical prediction of EMG: evidence that a kinetic brain-machine interface may be robust across altered movement dynamics

During typical movements, signals related to both the kinematics and kinetics of movement are mutually correlated, and each is correlated to some extent with the discharge of neurons in the primary motor cortex (M1). However, it is well known, if not always appreciated, that causality cannot be inferred from correlations. Although these mutual correlations persist, their nature changes with changing postural or dynamical conditions. Under changing conditions, only signals directly controlled by M1 can be expected to maintain a stable relationship with its discharge. If one were to rely on noncausal correlations for a brain-machine interface, its generalization across conditions would likely suffer. We examined this effect, using multielectrode recordings in M1 as input to linear decoders of both end point kinematics (position and velocity) and proximal limb myoelectric signals (EMG) during reaching. We tested these decoders across tasks that altered either the posture of the limb or the end point forces encountered during movement. Within any given task, the accuracy of the kinematic predictions tended to be somewhat better than the EMG predictions. However, when we used the decoders developed under one task condition to predict the signals recorded under different postural or dynamical conditions, only the EMG decoders consistently generalized well. Our results support the view that M1 discharge is more closely related to kinetic variables like EMG than it is to limb kinematics. These results suggest that brain-machine interface applications using M1 to control kinetic variables may prove to be more successful than the more standard kinematic approach.

The KineSpring load absorber implant: rationale, design and biomechanical characterization

Osteoarthritis (OA) of the knee is the leading cause of disability in the adult population. Although a number of treatments for knee OA are available, none effectively prevent OA progression. Currently, a wide therapeutic gap exists for patients who have unsuccessfully exhausted conservative OA treatments but who are hesitant or ineligible to undergo invasive surgery. The KineSpring device is a novel, joint preserving, minimally invasive implant that reduces medial compartment loading without significantly impacting the loading of the lateral compartment. This article describes the rationale for and the design of the KineSpring device and summarizes results of initial biomechanical testing in an OA cadaver model.

Concentric and eccentric isokinetic resistance training similarly increases muscular strength, fat-free soft tissue mass, and specific bone mineral measurements in young women

Women participated in 5 months of unilateral concentric (n = 37) or eccentric (n = 33) isokinetic resistance training of the legs and arms. Limb muscular strength increased as did total body, leg, and arm fat-free soft tissue mass, total body BMC, hip BMD, and forearm BMC and BMD. Isokinetic training benefits bone mineral acquisition.

INTRODUCTION AND HYPOTHESIS

Isokinetic resistance training (IRT) is osteogenic; however, it is not known if concentric or eccentric modalities of IRT produce differential effects on bone. We tested our hypothesis that high-load eccentric versus concentric mode of IRT would produce greater increases in muscular strength, fat-free soft tissue mass (FFSTM), bone mineral density (BMD) and content (BMC) in trained legs and arms.

METHODS

Participants were randomized to 5 months of concentric (n = 37) or eccentric (n = 33) training. The non-dominant leg and arm were used during training; dominant limbs served as controls. Muscular strength was measured with an isokinetic dynamometer; body composition was measured by dual-energy X-ray absorptiometry.

RESULTS

Muscular strength of the concentrically and eccentrically trained leg (18.6%; 28.9%) and arm (12.5%; 24.6%) significantly increased with training. Gains in total body (TB) BMC (p < 0.05) and, in the trained limbs, total proximal femur BMD (p < 0.05) and total forearm BMD (p < 0.05) and BMC (p < 0.05) occurred in both groups. FFSTM increased for the TB and trained leg and arm (all p < 0.001) in both modes.

CONCLUSION

Regardless of the mode, high-intensity, slow-velocity IRT increases muscular strength and FFSTM of trained limbs and imparts benefits to TB BMC and site-specific BMD and BMC in young women.

Direct comparison of the task-dependent discharge of M1 in hand space and muscle space

Since its introduction in the early 1980s, the concept of a "preferred direction" for neuronal discharge has proven to be a powerful means of studying motor areas of the brain. In the current paper, we introduce the concept of a "muscle-space"-preferred direction (PD(M)) that is analogous to the familiar hand-space-preferred direction (PD(H)). PD(M) reflects the similarity between the discharge of a given neuron and the activity of each muscle in much the way that PD(H) reflects the similarity of discharge with motion along each of the three Cartesian coordinate axes. We used PD(M) to analyze the data recorded from neurons in the primary motor cortex (M1) of three different monkeys. The monkeys performed center-out movements within two different cubical workspaces centered either to the left or right of the monkey's shoulder while we simultaneously recorded neuronal discharge, muscle activity, and limb orientation. We calculated preferred directions in both hand space and muscle space, and computed the angles between these vectors under a variety of conditions. PDs for different neurons were broadly distributed throughout both hand space and muscle space, but the muscle-space vectors appeared to form clusters of functionally similar neurons. In general, repeated estimates of PD(M) were more stable over time than were similar estimates of PD(H). Likewise, there was less change in PD(M) than in PD(H) for data recorded from the two different workspaces. However, although a majority of neurons had this muscle-like property, a significant minority was more stable in Cartesian hand space, reflecting a heterogeneity of function within M1.

Movement-related discharge in the cerebellar nuclei persists after local injections of GABA(A) antagonists

Limb movement-related neurons in the cerebellar nuclei (CN) typically produce bursts of discharge in association with movement. Consequently, given the inhibitory nature of the Purkinje cell (PC) projection to CN, it is puzzling that only a minority of movement-related PCs pause; the majority burst. Some of the movement-related CN activity may be the result of excitation from collaterals of mossy and climbing fiber projections to the cerebellar cortex. The only other input to CN is diffuse and neuromodulatory, from locus ceruleus and raphe nuclei. To investigate the role of the excitatory mossy fiber input, single units in CN were recorded in macaque monkeys during the performance of reaching and manipulation tasks, before and after blocking the PC input with local microinjections of GABA(A) antagonists (bicuculline or SR95531). After these injections, the movement-related modulation of CN discharge was greater and began earlier, compared with the modulation in the preinjection group of neurons. These observations indicate that an important excitatory drive is provided by extracerebellar inputs to CN, most likely from collaterals of mossy fibers. PCs may serve primarily to regulate this activity, by either pausing or bursting as necessary.

Low density of CD1+ cells in the synovial tissue of patients with rheumatoid arthritis

OBJECTIVE

CD1 molecules present microbial and self glycolipid antigens to a defined T cell subset with features of natural killer cells. CD1 molecules are up-regulated by inflammatory stimuli such as GM-CSF, and we would expect to find increased CD1 expression in the synovium of patients with rheumatoid arthritis (RA) as compared to osteoarthritis (OA). This study was initiated to compare the density of CD1a+, CD1b+, and CD1c+ synovial cells in RA and OA patients.

METHODS

Expression of CD1a+, CD1b+, and CD1c+ molecules in synovial tissue was assessed by semiquantitative immunohistochemistry. For comparison, serological, functional, and typical immunohistochemical markers of inflammation were detected.

RESULTS

Although patients with RA as compared to OA had highly significantly increased signs of inflammation, the density of CD1a+, CD1b+, and CD1c+ synovial cells was similar This was also true for the density of CD1+ cells in relation to that of activated CD163+ macrophages. There was a high correlation between the densities of CD1a,b,c positive cells, which suggests the existence of similar regulatory pathways. In a combined analysis of RA and OA patients, there existed a negative association between prior NSAID therapy and the density of CD1a+, CD1b+, and CD1c+ synoviocytes in relation to CD163+ macrophages. This is interesting because a similar immunosuppressive aspect of NSAID has never been shown before and this might represent a hitherto unrecognized immunosuppressive aspect of NSAID.

CONCLUSION

Considering the high synovial inflammation in patients with RA, the densities of CD1a+, CD1b+, and CD1c+ synovial cells were low compared to patients with OA. Further studies in RA patients are needed to clarify whether a defect in CD1 regulation may exist. Such a defect may lead to an insufficient immune response against microbial glycolipids, which would support smoldering or repeated inadequately responded infection.

Relationships among bone mineral density, body composition, and isokinetic strength in young women

The purpose of this study was to examine the relationships among bone mineral density (BMD), body composition, and isokinetic strength in young women. Subjects were 76 women (age: 20 +/- 2 yr, height: 164 +/- 6 cm, weight: 57 +/- 6 kg, body fat: 27 +/- 4%) with a normal body mass index (18-25 kg/m(2)). Total body, nondominant proximal femur, and nondominant distal forearm BMD were measured with dual-energy x-ray absorptiometry. Isokinetic concentric (CON) and eccentric (ECC) strength of the nondominant thigh and upper arm were measured at 60 deg/sec. Fat-free mass (FFM) correlated (P < 0.001) with BMD of the total body (r = 0.56) and femoral neck (r = 0.52), whereas fat mass (FM) did not relate to BMD at any site. Leg FFM, but not FM, correlated with BMD in all regions of interest at the proximal femur. Weak associations were observed between arm FFM and forearm BMD. Isokinetic strength did not relate to BMD at any site after correcting for regional FFM. In conclusion, strong, independent associations exist between BMD and FFM, but not FM or isokinetic strength, in young women.

The effect of urethral instrumentation on uroflowmetry

OBJECTIVE

To evaluate in a prospective study the effect of urethral instrumentation (flexible cystoscopy) on uroflowmetry, and in particular the peak urinary flow rate (Qmax).

PATIENTS AND METHODS

Thirty-two consecutive patients (median age 61.8 years, range 24-80) undergoing flexible cystoscopy were included in the analysis. Patients with active urethral stricture disease or urinary infection were excluded. The indications for cystoscopy included haematuria (44%), voiding symptoms (66%), history of bladder cancer (19%), and history of perineal trauma (3%). Patients underwent uroflowmetry immediately before instrumentation. The postvoid residual volume (PVR) was measured by bladder catheterization. After cystoscopy the bladder was completely emptied and then filled with the same volume of sterile normal saline (bladder volume = voided volume + PVR), and the patient underwent a second uroflowmetry.

RESULTS

Patients with voiding symptoms (21, 66%) had a median (range) American Urological Association symptom score of 17 (4-34), a Bother score of 16 (1-23), and Quality of Life score of 3 (1-6). The mean Qmax was 16.9 (4.5-36.9) and 13.3 (4.5-39.4) mL/s before and after cystoscopy, respectively (P = 0.029). The mean percentage difference in Qmax was + 27 (- 23 to 139)% higher before than after cystoscopy. After cystoscopy, up to 25% (eight) and 21% (seven) patients had a lower Qmax, from > 15 to < 15 mL/s and from > 12 to < 12 mL/s, respectively. There were no significant differences in the bladder volume and PVR (P = 0.914 and 0.984, respectively).

CONCLUSIONS

Urethral instrumentation by flexible cystoscopy significantly alters Qmax. A 'false' mean change in Qmax (favouring improvement) of +27% would result if uroflowmetry data after instrumentation were used at baseline. Therefore, study protocols for benign prostatic obstruction should exclude uroflowmetry data obtained after urethral instrumentation; failure to exclude such data will lead to disproportionately greater improvements in Qmax that are independent of the therapy delivered.

Prediction of muscle activity by populations of sequentially recorded primary motor cortex neurons

We have adopted an analysis that produces a post hoc prediction of the time course of electromyogram (EMG) activity from the discharge of ensembles of neurons recorded sequentially from the primary motor cortex (M1) of a monkey. Over several recording sessions, we collected data from 50 M1 neurons and several distal forelimb muscles during a stereotyped precision grip task. Ensemble averages were constructed from 5 to 10 trials for each neuron and EMG signal. We used multiple linear regression on randomly chosen subsets of these neurons to find the best fit between the neuronal and EMG data. The fixed delay between neuronal and EMG signals that yielded the largest coefficient of determination (R(2)) between predicted and actual EMG was 50 ms. R(2) averaged 0.83 for ensembles composed of 15 neurons. If, instead, each neuronal signal was delayed by the time of its peak cross-correlation with the EMG signal, R(2) increased to 0.88. Using all 50 neurons, R(2) under these conditions averaged nearly 0.97. A similar analysis was conducted with signals recorded during both a power grip and a precision grip task. Quality of the fit dropped dramatically when parameters from the precision grip for a given set of neurons were used to fit data recorded during the power grip. However, when a single set of regression parameters was used to fit a combination of the two tasks, the quality of the fits decreased by <10% from that of a single task.

Features of motor performance that drive adaptation in rapid hand movements

In order to explore how subjects correct for errors in movement and adapt their motor programs, we studied rapid hand movements. Subjects grasped a grooved knob and made brisk turning movements to various targets, similar to tuning a radio dial. A motor attached to the knob shaft was configured to apply a destabilizing negative viscous perturbation. Following a period of practice with no perturbations, the negative viscosity was engaged, which caused a large change in overall kinematics: the peak velocity increased, the movement amplitude was too large, and discrete corrective submovements were generated to bring the pointer back onto the target. After about an hour and nearly 1000 trials, subjects learned to move accurately in the new dynamic environment, returning their overall kinematics near to previous levels. Measures of performance included the endpoint error of the primary movement (the initial movement segment), the frequency and amplitude of corrective submovements, task success rate, mean squared jerk, and deviation from a "normal" angular velocity temporal profile. Both the amplitude and frequency of corrective submovements decreased progressively during adaptation as the subjects made fewer target overshoot errors. These results are consistent with motor learning schemes in which adaptation of the motor controller is driven by an attempt to reduce the endpoint error of the primary movement. While there have been many theories regarding what is being optimized in motor control, in general, biologically plausible mechanisms for implementing these schemes have not been described. A biologically plausible optimization criterion is the minimization of the occurrence and amplitude of corrective submovements, since the latter have been proposed as realistic climbing fiber training signals for adaptive changes in the cerebellum. We postulate that the other criteria that have been proposed are instead secondary to an increased accuracy of the primary movement and a corresponding decrease in the occurrence and amplitude of corrective submovements.

Primary motor cortical neurons encode functional muscle synergies

Many different kinematic and kinetic signals have been proposed as possible variables under the control of the primary motor cortex. Despite the presence of direct projections to motor neurons, muscle activation has received less attention as a controlled variable. Furthermore, although it is well known that descending fibers project to multiple motor pools, an objective, quantitative study of the relation between neuronal modulation and the activity of groups of muscles has not previously been reported. We have recorded the discharge of 310 neurons located in the primary motor cortex of two monkeys, along with the activity of a variety of arm and hand muscles. Data were recorded while the monkey reached to and pressed a series of illuminated buttons. The similarity of a given neuron's discharge with respect to each muscle was determined by calculating the linear cross-correlation between its discharge rate and each rectified, filtered electromyogram. A "functional linkage vector" was then constructed, which expressed the similarity of that neuron's discharge to the entire set of muscles. We discovered discrete groups of functional linkage vectors within the high order muscle space for both monkeys which corresponded to functional properties of the neurons measured by other methods. Several of these groups appeared to represent a functional synergy of muscles, such as those required to extend the limb, press a button, or open the hand in preparation for the press. When the dimensionality of this space was reduced by a principal components analysis, the originally identified clusters of neurons remained well separated. These results are consistent with the hypothesis that the discharge of individual neurons in the primary motor cortex encodes the activity of a relatively small number of functionally relevant groups of muscles. It will be important to determine whether these results will also apply to more complex behavior, and to what extent these functional muscle synergy representations remain fixed across behaviors.

The role of the cerebellum in modulating voluntary limb movement commands

We recorded the activity of cerebellar Purkinje cells (PCs), primary motor cortical (M1) neurons, and limb EMG signals while monkeys executed a sequential reaching and button pressing task. PC simple spike discharge generally correlated well with the activity of one or more forelimb muscles. Surprisingly, given the inhibitory projection of PCs, only about one quarter of the correlations were negative. The largest group of neurons burst during movement and were positively correlated with EMG signals, while another significant group burst and were negatively correlated. Among the PCs that paused during movement most were negatively correlated with EMG. The strength of these various correlations was somewhat weaker, on average, than equivalent correlations between M1 neurons and EMG signals. On the other hand, there were no significant differences in the timing of the onset of movement related discharge among these groups of PCs, or between the PCs and M1 neurons. PC discharge was modulated largely in phase, or directly out of phase, with muscle activity. The nearly synchronous activation of PCs and muscles yielded positive correlations, despite the fact that the synaptic effect of the PC discharge is inhibitory. The apparent function of this inhibition is to restrain activity in the limb premotor network, shaping it into a spatiotemporal pattern that is appropriate for controlling the many muscles that participate in this task. The observed timing suggests that the cerebellar cortex learns to modulate PC discharge predictively. Through the cerebellar nucleus, this PC signal is combined with an underlying cerebral cortical signal. In this manner the cerebellum refines the descending command as compared with the relatively crude version generated when the cerebellum is damaged.

The use of overlapping submovements in the control of rapid hand movements

Rapid targeted movements are subject to special control considerations, since there may be inadequate time available for either visual or somatosensory feedback to be effective. In our experiments, subjects rapidly rotated a knob to align a pointer to one of several targets. We recognized three different types of movement segments: the primary movement, and two types of submovement, which frequently followed. The submovements were initiated either before or after the end of the primary movement. The former, or "overlapping" type of submovement altered the kinematics of the overall movement and was consequently difficult to detect. We used a direct, objective test of movement regularity to detect overlapping submovements, namely, examining the number of jerk and snap zero crossings during the second half of a movement. Any overlapping submovements were parsed from the overall movement by subtracting the velocity profile of the primary movement. The velocity profiles of the extracted submovements had near-symmetric bell shapes, similar to the shapes of both pure primary movements and nonoverlapping submovements. This suggests that the same neural control mechanisms may be responsible for producing all three types of movement segments. Overlapping submovements corrected for errors in the amplitude of the primary movement. Furthermore, they may account for the previously observed, speed-dependent asymmetry of the velocity profile. We used a nonlinear model of the musculoskeletal system to explain most of the kinematic features of these rapid hand movements, including how discrete submovements are superimposed on a primary movement. Finally, we present a plausible scheme for how the central nervous system may generate the commands to control these rapid hand movements.

A possible role of the superior colliculus in eye-hand coordination

Reaching with the arm to a newly appearing target is usually preceded by a saccadic eye movement. Neurons in the superior colliculus (SC) constitute one important brain structure controlling saccades. Yet, the SC also contains reach neurons activated during arm movements, whose location extends also deeper into the underlying mesencephalic reticular formation. Reach neurons can be divided into two classes based on their different modulation with respect to gaze position. For the first class, the gaze-independent reach neurons, the activity does not depend on which location is currently fixated, but solely on the position and movement of the (usually contralateral) arm. There is a correlation of the activity of these neurons with the activity of shoulder muscles. The second class, the gaze-related reach neurons, are active for reaches into a specific area relative to the current point of gaze. This means the target has to project on a certain part of the retina, while it is not important which arm is used or by which trajectory the target will be reached. Many fixation neurons in the rostral pole of the SC discharge tonically during fixation and pause during saccades. For some fixation neurons, the activity can be increased during simultaneous arm movements, for others decreased. Two psychophysical experiments with healthy human subjects show possible behavioral correlates of an interaction between these reach neurons and visuomotor neurons within the SC.

Verification of good production practices that reduce the risk of exposure of pigs to Trichinella

Control of Trichinella infection in swine has traditionally been accomplished by inspection of individual carcasses or by post-slaughter processing to inactivate parasites. Recent declines in prevalence of this parasite in domestic swine, coupled with improvements in swine management systems, offer the opportunity to document pork safety during the production phase. We report here on a certification pilot study using an audit to document good production practices for swine relative to the risk of exposure to trichinae. Based on the results, improvements in the program have been made and further studies will be undertaken prior to launching a voluntary trichinae herd certification program in the United States.

Context dependency in the globus pallidus internal segment during targeted arm movements

Extracellular discharges from single neurons in the internal segment of the globus pallidus (GPi) were recorded and analyzed for rate changes associated with visually guided forearm rotations to four different targets. We sought to examine how GPi neurons contribute to movement preparation and execution. Unit discharge from 108 GPi neurons recorded in 35 electrode penetrations was aligned to the time of various behavioral events, including the onset of cued and return movements. In total, 39 of 108 GPi neurons (36%) were task-modulated, demonstrating statistically significant changes in discharge rate at various times between the presentation of visual cues and movement generation. Most often, strong modulation in discharge rate occurred selectively during either the cued (n = 32) or return (n = 2) phases of the task, although a few neurons (n = 5) were well-modulated during both movement phases. Of the 34 neurons that were modulated exclusively during cued or return movements, 50% (n = 17) were modulated similarly in association with movements to any target. The remaining 17 neurons exhibited considerable diversity in their discharge properties associated with movements to each target. Cued phases of behavior were always rewarded if executed correctly, whereas return phases were never rewarded. Overall, these data reveal that many GPi neurons discharged in a context-dependent manner, being modulated during cued, rewarded movements, but not during similar self-paced, unrewarded movements. When considered in the light of other observations, the context-dependence we have observed seems likely to be influenced by the animal's expectation of reward.

Neuropeptide Y cotransmission with norepinephrine in the sympathetic nerve-macrophage interplay

The CNS modulates immune cells by direct synaptic-like contacts in the brain and at peripheral sites, such as lymphoid organs. To study the nerve-macrophage communication, a superfusion method was used to investigate cotransmission of neuropeptide Y (NPY) with norepinephrine (NE), with interleukin (IL)-6 secretion used as the macrophage read-out parameter. Spleen tissue slices spontaneously released NE, NPY, and IL-6 leading to a superfusate concentration at 3-4 h of 1 nM:, 10 pM:, and 120 pg/ml, respectively. Under these conditions, NPY dose-dependently inhibited IL-6 secretion with a maximum effect at 10(-10) M: (p = 0.012) and 10(-9) M: (p < 0.001). Simultaneous addition of NPY at 10(-9) M: and the alpha-2-adrenergic agonist p-aminoclonidine further inhibited IL-6 secretion (p < 0.05). However, simultaneous administration of NPY at 10(-9) M: and the beta-adrenergic agonist isoproterenol at 10(-6) M: or NE at 10(-6) M: significantly increased IL-6 secretion (p < 0.005). To objectify these differential effects of NPY, electrical field stimulation of spleen slices was applied to release endogenous NPY and NE. Electrical field stimulation markedly reduced IL-6 secretion, which was attenuated by the NPY Y1 receptor antagonist BIBP 3226 (10(-7) M, p = 0.039; 10(-8) M, p = 0.035). This indicates that NPY increases the inhibitory effect of endogenous NE, which is mediated at low NE concentrations via alpha-adrenoceptors. Blockade of alpha-adrenoceptors attenuated electrically induced inhibition of IL-6 secretion (p < 0.001), which was dose-dependently abrogated by BIBP 3226. This indicates that under blockade of alpha-adrenoceptors endogenous NPY supports the stimulating effect of endogenous NE via beta-adrenoceptors. These experiments demonstrate the ambiguity of NPY, which functions as a cotransmitter of NE in the nerve-macrophage interplay.

Neurotransmitter modulation of interleukin 6 (IL-6) and IL-8 secretion of synovial fibroblasts in patients with rheumatoid arthritis compared to osteoarthritis

OBJECTIVE

The sensory nervous system with the 2 neurotransmitters substance P (SP) and calcitonin gene related peptide (CGRP) is proinflammatory in experimental models of arthritis. The role of the sympathetic nervous system with norepinephrine (NE), adenosine, beta-endorphin, and methionine enkephalin (MENK) is not clearly understood. We studied the influence of these neurotransmitters on secretion of interleukin 6 (IL-6) and IL-8 in primary cultures of synovial fibroblasts of patients with rheumatoid arthritis (RA) compared to osteoarthritis (OA).

METHODS

Fibroblasts were isolated using fresh synovial tissue of 5 patients with RA and 5 with OA who underwent knee joint replacement surgery. Modulation of spontaneous secretion of IL-6 and IL-8 was investigated in vitro using the neurotransmitters noted above.

RESULTS

In RA fibroblasts, CGRP increased IL-6 and IL-8 secretion at 10(-10) to 10(-8) M (p at least < 0.01), which was not observed in OA fibroblasts. SP had no effect on either cytokine in RA fibroblasts but stimulated IL-8 secretion at 10(-8) M in OA fibroblasts (p < 0.01). In RA fibroblasts, adenosine and NE inhibited secretion of both cytokines at low concentrations (10(-8) M; p < 0.01). However, in OA fibroblasts there was a NE induced increase of IL-8 and IL-6 secretion at 10(-7) and 10(-6) M (p < 0.01), but no inhibition at lower concentrations (10(-8) M; p = NS). In RA fibroblasts, beta-endorphin and MENK inhibited IL-8 secretion at 10(-9) to 10(-7) M (p < 0.01), whereas in OA fibroblasts the dose response curve was shifted to lower concentrations (10(-12) M, 10(-11) M; p < 0.01).

CONCLUSION

In OA fibroblasts, the sympathetic neurotransmitters were stimulatory at higher concentrations. CGRP was the most potent stimulatory neurotransmitter in RA fibroblasts whereas the sympathetic adenosine, NE, beta-endorphin, and MENK were inhibitory. This indicates a dualism of action of sympathetic and sensory neurotransmitters, with inhibitory and stimulatory effects on cytokine secretion of RA fibroblasts.

The loss of sympathetic nerve fibers in the synovial tissue of patients with rheumatoid arthritis is accompanied by increased norepinephrine release from synovial macrophages

Our objective was to investigate sympathetic and sensory nerve fibers in synovial tissue in rheumatoid arthritis (RA) and osteoarthritis (OA) in relation to histological inflammation and synovial cytokine and norepinephrine (NE) secretion. Immunohistochemistry was used to detect nerve fibers and inflammatory parameters. A superfusion technique of synovial tissue pieces was used to investigate cytokine and NE secretion. In RA, we detected 0.2 +/- 0.04 tyrosine hydroxylase-positive (TH-positive=sympathetic) nerve fibers/mm2 as compared to 4.4 +/- 0. 8 nerve fibers/mm2 in OA (P<0.001). In RA, there was a negative correlation between the number of TH-positive nerve fibers and inflammation index (RRank=-0.705, P=0.002) and synovial IL-6 secretion (RRank=-0.630, P=0.009), which was not found in OA. Substance P-positive (=sensory) nerve fibers were increased in RA as compared to OA (3.5+/-0.2 vs. 2.3+/-0.3/mm2, P=0.009). Despite lower numbers of sympathetic nerve fibers in RA than in OA, NE release was similar at baseline (RA vs. OA: 152+/-36 vs. 106+/-21 pg/ml, n.s.). Basal synovial NE secretions correlate with the number of TH-positive CD 163+ synovial macrophages (RA: RRank=0.622, P=0.031; OA: RRank=0.299, n.s.), and synovial macrophages have been shown to produce NE in vitro. Whereas sympathetic innervation is reduced, sensory innervation is increased in the synovium from patients with longstanding RA when compared to the synovium from OA patients. The differential patterns of innervation are dependent on the severity of the inflammation. However, NE secretion from the synovial tissue is maintained by synovial macrophages. This demonstrates a loss of the influence of the sympathetic nervous system on the inflammation, accompanied by an up-regulation of the sensory inputs into the joint, which may contribute to the maintenance of the disease.

Cytokines and hormones as possible links between endocrinosenescence and immunosenescence

Deterioration of the immune system and the endocrine system during aging is thought to contribute to increased morbidity and mortality. Since bidirectional interrelations of both systems are present in the young and in the elderly, endocrinosenescence modulates the immune system and immunosenescence changes the endocrine system. This review focuses on age-related changes of the two systems and provides examples for the interaction of both systems during aging. It is demonstrated that both systems modulate each other in a probably unfavorable way which may be a cofactor in the aging process. Understanding of these bidirectional physiological mechanisms will help to define targets for therapeutical intervention to improve the health of aging people.

A randomized prospective trial of intrarectal lidocaine for pain control during transrectal prostate biopsy: the Emory University experience

PURPOSE

We prospectively evaluated the safety and efficacy of intrarectal lidocaine gel as anesthesia during transrectal prostate biopsy.

MATERIALS AND METHODS

Of 63 consecutive men undergoing transrectal prostate biopsy 50 who qualified were enrolled in this study. Indications for the procedure were an abnormal prostate on digital rectal examination and/or elevated serum prostate specific antigen. Patients were randomized into group 1-25 who received 10 cc of 2% intrarectal lidocaine 10 minutes before the procedure and group 2-25 controls. No narcotics, sedation or analgesia was given. Pain during biopsy was assessed using a 10-point linear visual analog pain scale.

RESULTS

In groups 1 and 2 median patient age was 63 and 66 years (p = 0.139), and median prostate specific antigen was 6.04 (range 1.07 to 263) and 7.24 (range 1.34 to 51.82) ng./ml. (p = 0.337). Digital rectal examination was normal and abnormal in 17 and 15 group 1, and in 8 and 10 group 2 patients, respectively. Ultrasound showed a median prostate volume of 43.6 cc (range 15.3 to 124) in group 1 and 40.3 (range 19.8 to 132) in group 2 (p = 0.710). Final histological results revealed prostate cancer in 7 men (28%) in each group. The median pain score during transrectal prostate biopsy was 2 (range 1 to 5) and 5 (range 1 to 7) in groups 1 and 2, respectively (p = 0.00001). No adverse events were noted.

CONCLUSIONS

Intrarectal lidocaine gel is a simple, safe and efficacious method of providing satisfactory anesthesia in men undergoing transrectal prostate biopsy. We recommend its routine administration in all patients during this procedure.