Background: Dexterous prosthetic hands that were developed recently, such as SmartHand and i-LIMB, are highly sophisticated; they have individually controllable fingers and the thumb that is able to abduct/adduct. This flexibility allows implementation of many different grasping strategies, but also requires new control algorithms that can exploit the many degrees of freedom available. The current study presents and tests the operation of a new control method for dexterous prosthetic hands. Methods: The central component of the proposed method is an autonomous controller comprising a vision system with rule-based reasoning mounted on a dexterous hand (CyberHand). The controller, termed cognitive vision system (CVS), mimics biological control and generates commands for prehension. The CVS was integrated into a hierarchical control structure: 1) the user triggers the system and controls the orientation of the hand; 2) a high-level controller automatically selects the grasp type and size; and 3) an embedded hand controller implements the selected grasp using closed-loop position/force control. The operation of the control system was tested in 13 healthy subjects who used Cyberhand, attached to the forearm, to grasp and transport 18 objects placed at two different distances. Results: The system correctly estimated grasp type and size (nine commands in total) in about 84% of the trials. In an additional 6% of the trials, the grasp type and/or size were different from the optimal ones, but they were still good enough for the grasp to be successful. If the control task was simplified by decreasing the number of possible commands, the classification accuracy increased (e.g., 93% for guessing the grasp type only). Conclusions: The original outcome of this research is a novel controller empowered by vision and reasoning and capable of high-level analysis (i.e., determining object properties) and autonomous decision making (i.e., selecting the grasp type and size). The automatic control eases the burden from the user and, as a result, the user can concentrate on what he/she does, not on how he/she should do it. The tests showed that the performance of the controller was satisfactory and that the users were able to operate the system with minimal prior training.

From the editors

Nature Reviews Neuroscience 11, 607 (2010). doi:10.1038/nrn2910

This issue of Nature Reviews Neuroscience features articles on olfactory perception, the neural code, psychedelic drugs and the influence of socioeconomic status (SES) on development.In a Review article on page 628, Gottfried highlights principles that underlie central mechanisms of odour object perception.

Neurodegenerative disease: The missing link

Nature Reviews Neuroscience 11, 608 (2010). doi:10.1038/nrn2904

Author: Claudia Wiedemann

tau regulates the interaction of postsynaptic density protein 95 (PSD95) with NMDA (N-methyl-D-aspartate) receptors, which are thought to mediate Aβ toxicity.

Neurodegenerative disease: microRNAs under threat from LRRK2

Nature Reviews Neuroscience 11, 609 (2010). doi:10.1038/nrn2906

Author: Claudia Wiedemann

translational regulation of E2F1 and DP by miRNAs is implicated in LRRK2-mediated pathogenesis in Parkinson's disease.

Neuron–glia interactions: Astrocytes in the air

Nature Reviews Neuroscience 11, 610 (2010). doi:10.1038/nrn2905

Author: Leonie Welberg

Astrocytes control breathing through pH-dependent release of ATP.

In brief

Nature Reviews Neuroscience 11, 611 (2010). doi:10.1038/nrn2908

NeurotransmittersDopaminergic network differences in human impulsivityBuckholtz, J. W.et al. Science329, 532 (2010)Dopamine (DA) is thought to have a role in impulsivity, but the mechanisms are unclear. The authors estimated midbrain D2 and D3 (inhibitory)

Synaptic plasticity: Assertive authorities

Nature Reviews Neuroscience 11, 612 (2010). doi:10.1038/nrn2909

Author: Claudia Wiedemann

SIRT1 modulates synaptic plasticity through microRNA-dependent regulation of the transcription factor cAMP-responsive element-binding (CREB) protein.

In brief

Nature Reviews Neuroscience 11, 613 (2010). doi:10.1038/nrn2907

AgeingAttentuation of age-related changes in mouse neuromuscular synapses by caloric restriction and exerciseValdez, G.et al. Proc. Natl Acad. Sci. USA2 Aug 2010 (doi:10.1073/pnas.1002220107)Age-related cognitive decline might be due to synaptic alterations. Here, the authors studied

Spiking activity propagation in neuronal networks: reconciling different perspectives on neural coding

Nature Reviews Neuroscience 11, 615 (2010). doi:10.1038/nrn2886

Authors: Arvind Kumar, Stefan Rotter & Ad Aertsen

The brain is a highly modular structure. To exploit modularity, it is necessary that spiking activity can propagate from one module to another while preserving the information it carries. Therefore, reliable propagation is one of the key properties of a candidate neural code. Surprisingly, the

Socioeconomic status and the brain: mechanistic insights from human and animal research

Nature Reviews Neuroscience 11, 651 (2010). doi:10.1038/nrn2897

Authors: Daniel A. Hackman, Martha J. Farah & Michael J. Meaney

Human brain development occurs within a socioeconomic context and childhood socioeconomic status (SES) influences neural development — particularly of the systems that subserve language and executive function. Research in humans and in animal models has implicated prenatal factors, parent–child interactions and cognitive stimulation in the

Background: Three-dimensional kinematic analysis equipment is a valuable instrument for studying the execution of movement during functional activities of the upper limbs. The aim of this study was to analyze the kinematic differences in the execution of a daily activity such as drinking from a glass between two groups of patients with tetraplegia and a control group. Methods: A total of 24 people were separated into three groups for analysis: 8 subjects with metameric level C6 tetraplegia, 8 subjects with metameric level C7 tetraplegia and 8 control subjects (CG). A set of active markers that emit infrared light were positioned on the upper limb. Two scanning units were used to record the sessions. The activity of drinking from a glass was broken down into a series of clearly identifiable phases to facilitate analysis. Movement times, velocities, and the joint angles of the shoulder, elbow and wrist in the three spatial planes were the variables analyzed. Results: The most relevant differences between the three groups were in the wrist. Wrist palmar flexion during the back transport phase was greater in the patients with C6 and C7 tetraplegia than in the CG, whereas the highest wrist dorsal flexion values were in forward transport in the subjects with C6 or C7 tetraplegia, who required complete activation of the tenodesis effect to complete grasping. Conclusions: A detailed description was made of the three-dimensional kinematic analysis of the task of drinking from a glass in healthy subjects and in two groups of patients with tetraplegia. This was a useful application of kinematic analysis of upper limb movement in a clinical setting. Better knowledge of the execution of this movement in each of these groups allows therapeutic recommendations to be specifically adapted to the functional deficit present. This information can be useful in designing wearable robots to compensate the performance of AVD, such as drinking, in people with cervical SCI.

The neurobiology of psychedelic drugs: implications for the treatment of mood disorders

Nature Reviews Neuroscience 11, 642 (2010). doi:10.1038/nrn2884

Authors: Franz X. Vollenweider & Michael Kometer

After a pause of nearly 40 years in research into the effects of psychedelic drugs, recent advances in our understanding of the neurobiology of psychedelics, such as lysergic acid diethylamide (LSD), psilocybin and ketamine have led to renewed interest in the clinical potential of psychedelics

Background: Experiencing independent mobility is important for children with a severe movement disability, but learning to drive a powered wheelchair can be labor intensive, requiring hand-over-hand assistance from a skilled therapist. Methods: To improve accessibility to training, we developed a robotic wheelchair trainer that steers itself along a course marked by a line on the floor using computer vision, haptically guiding the driver's hand in appropriate steering motions using a force feedback joystick, as the driver tries to catch a mobile robot in a game of "robot tag". This paper provides a detailed design description of the computer vision and control system. In addition, we present data from a pilot study in which we used the chair to teach children without motor impairment aged 4-9 (n = 22) to drive the wheelchair in a single training session, in order to verify that the wheelchair could enable learning by the non-impaired motor system, and to establish normative values of learning rates.Results and DiscussionTraining with haptic guidance from the robotic wheelchair trainer improved the steering ability of children without motor impairment significantly more than training without guidance. We also report the results of a case study with one 8-year-old child with a severe motor impairment due to cerebral palsy, who replicated the single-session training protocol that the non-disabled children participated in. This child also improved steering ability after training with guidance from the joystick by an amount even greater than the children without motor impairment. Conclusions: The system not only provided a safe, fun context for automating driver's training, but also enhanced motor learning by the non-impaired motor system, presumably by demonstrating through intuitive movement and force of the joystick itself exemplary control to follow the course. The case study indicates that a child with a motor system impaired by CP can also gain a short-term benefit from driver's training with haptic guidance.

Background: Studying the changes that occur in motor unit potential trains (MUPTs) may provide insight into the extent of motor unit loss and neural re-organization resulting from nerve compression injury. The purpose of this study was to determine the feasibility of using decomposition-based quantitative electromyography (DQEMG) to study the pathophysiological changes associated with compression neuropathy. Methods: The model used to examine compression neuropathy was carpal tunnel syndrome (CTS) due to its high prevalence and ease of diagnosis. Surface and concentric needle electromyography data were acquired simultaneously from the abductor pollicis brevis muscle in six individuals with severe CTS, eight individuals with mild CTS and nine healthy control subjects. DQEMG was used to detect intramuscular MUPTs during constant-intensity contractions and to estimate parameters associated with the surface- and needle-detected motor unit potentials (SMUPs and MUPs, respectively). MUP morphology and stability, SMUP morphology and motor unit number estimates (MUNEs) were compared among the groups using Kruskal-Wallis tests. Results: The severe CTS group had larger amplitude and longer duration MUPs and smaller MUNEs than the mild CTS and control groups, suggesting that the individuals with severe CTS had motor unit loss with subsequent collateral reinnervation, and that DQEMG using a constant-intensity protocol was sensitive to these changes. SMUP morphology and MUP complexity and stability did not significantly differ among the groups. Conclusions: These results provide evidence that MUP amplitude parameters and MUNEs obtained using DQEMG, may be a valuable tool to investigate pathophysiological changes in muscles affected by compressive motor neuropathy to augment information obtained from nerve conduction studies. Although there were trends in many of these measures, in this study, MUP complexity and stability and SMUP parameters were, of limited value.

Neuron–glia interactions: A tunnel signal

Nature Reviews Neuroscience 11, 610 (2010). doi:10.1038/nrn2901

Author: Leonie Welberg

New neurons control, through Slit-Robo signalling, the organization of the glial tubes through which they migrate in the RMS.

Multiple Sclerosis: Putting a dampener on inflammation

Nature Reviews Neuroscience 11, 610 (2010). doi:10.1038/nrn2903

Author: Katie Kingwell

Signalling by metabotropic glutamate receptor 4 counteracts neuroinflammation in a rodent model of multiple sclerosis.

Neuroendocrinology: Housing conditions affect tumour growth

Nature Reviews Neuroscience 11, 613 (2010). doi:10.1038/nrn2902

Author: Nicola McCarthy

Mice that experience an enriched environment are more resistant to tumour growth.

Central mechanisms of odour object perception

Nature Reviews Neuroscience 11, 628 (2010). doi:10.1038/nrn2883

Author: Jay A. Gottfried

The stimulus complexity of naturally occurring odours presents unique challenges for central nervous systems that are aiming to internalize the external olfactory landscape. One mechanism by which the brain encodes perceptual representations of behaviourally relevant smells is through the synthesis of different olfactory inputs into

Neurogenomics: Parental influences run deep

Nature Reviews Neuroscience 11, 609 (2010). doi:10.1038/nrn2899

Author: Cristian Bodo

Genomic imprinting is widespread in the mouse brain and shows sexual dimorphism.