News Story on Italy's MIT Disappoints

We were surprised by the tone and content of the News of the Week story by L. Margottini about the new Italian Institute of Technology (IIT) ("Italy's MIT grows, and so does controversy," 19 June, p. [1502][1]). The remark that international competition was ignored in recruiting IIT scientists is patently false. IIT, at its inception in 2005, set up international competitions for both senior and junior investigators. These positions were advertised widely in scientific journals, including Science and Nature . As a result of this international search, four of the six appointed IIT research directors come from abroad, and among junior appointments, one-third are Italians returning from abroad, one-third are Italians already residing in Italy, and one-third are foreigners. Also untrue is Margottini's reported concern that IIT's scientific roster includes big names who do not do the bulk of their work at IIT. Recently appointed senior scientists might continue working at a previous institution for some time while their laboratory space at IIT is refurbished and equipment is ordered. However, after this setup period they do their work onsite. Margottini's story is largely based on a report written by Mario Rasetti and Elio Raviola, who visited the institute on 6 June 2007, barely 11 months after the first directors were selected, and before any labs were operational. The IIT laboratories started in a 25,000-m2 facility that was first made available in January 2006. As such, Rasetti and Raviola's report was documenting a work in progress and was designed to monitor the early stages of the Institute's development. Their report reflects problems typical of the birth of new institutions. Nonetheless, the report was regarded, on balance, as positive, and IIT was indeed given continued support. The News story does not mention the substantial progress achieved by IIT in the past 2 years. After the review by Rasetti and Raviola, an independent international advisory board made an onsite evaluation of IIT in December 2008 and a general assessment in May 2009; both gave IIT a ringing endorsement. The May 2009 report concludes that "[i]n general, both the accomplishments of the past three years and the future plans seem excellent" (R. Horvitz, Nobel Laureate), and that "[t]he IIT initiative has been remarkably successful…the quality of the new members is very high and would be competitive in all highly developed countries" (P. Greengard, Nobel Laureate) ([ 1 ][2]). Like all major scientific endeavors, IIT has had some growing pains, but we believe it has a very bright future. The best evidence is something that Margottini overlooks in her article: Scores of excellent young Italian and foreign researchers have returned to Italy or come to Italy for the first time to work at IIT. 1. [↵][3] 1. E. Bizzi 2. et al ., "Evaluation report of Technical and Scientific Committee of the IIT-Foundation" (09 May 2009). [1]: /lookup/doi/10.1126/science.324_1502 [2]: #ref-1 [3]: #xref-ref-1-1 "View reference 1 in text

A Hard Scientific Quest: Understanding Voluntary Movements

In this article we explore the complexities of what goes on in the brain when one wishes to perform even the simplest everyday movements. In doing so, we describe experiments indicating that the spinal cord interneurons are organized in functional modules and that each module activates a distinct set of muscles. Through these modules the central nervous system has found a simple solution to controlling the large number of muscle fibers active even during the execution of the simplest action. We also explore the many different neural signals that contribute to pattern formations, including afferent information from the limbs and information of motor memories.National Science Foundation (U.S.) (Grant IIS-0904594)National Institutes of Health (U.S.) (Grant NS44393)National Institutes of Health (U.S.) (Grant NS068103

An Optogenetic Demonstration of Motor Modularity in the Mammalian Spinal Cord

Motor modules are neural entities hypothesized to be building blocks of movement construction. How motor modules are underpinned by neural circuits has remained obscured. As a first step towards dissecting these circuits, we optogenetically evoked motor outputs from the lumbosacral spinal cord of two strains of transgenic mice – the Chat, with channelrhodopsin (ChR2) expressed in motoneurons, and the Thy1, expressed in putatively excitatory neurons. Motor output was represented as a spatial field of isometric ankle force. We found that Thy1 force fields were more complex and diverse in structure than Chat fields: the Thy1 fields comprised mostly non-parallel vectors while the Chat fields, mostly parallel vectors. In both, most fields elicited by co-stimulation of two laser beams were well explained by linear combination of the separately-evoked fields. We interpreted the Thy1 force fields as representations of spinal motor modules. Our comparison of the Chat and Thy1 fields allowed us to conclude, with reasonable certainty, that the structure of neuromotor modules originates from excitatory spinal interneurons. Our results not only demonstrate, for the first time using optogenetics, how the spinal modules follow linearity in their combinations, but also provide a reference against which future optogenetic studies of modularity can be compared

Synergy temporal sequences and topography in the spinal cord: evidence for a traveling wave in frog locomotion

Locomotion is produced by a central pattern generator. Its spinal cord organization is generally considered to be distributed, with more rhythmogenic rostral lumbar segments. While this produces a rostrocaudally traveling wave in undulating species, this is not thought to occur in limbed vertebrates, with the exception of the interneuronal traveling wave demonstrated in fictive cat scratching (Cuellar et al. J Neurosci 29:798–810, 2009). Here, we reexamine this hypothesis in the frog, using the seven muscle synergies A to G previously identified with intraspinal NMDA (Saltiel et al. J Neurophysiol 85:605–619, 2001). We find that locomotion consists of a sequence of synergy activations (A–B–G–A–F–E–G). The same sequence is observed when focal NMDA iontophoresis in the spinal cord elicits a caudal extension-lateral force-flexion cycle (flexion onset without the C synergy). Examining the early NMDA-evoked motor output at 110 sites reveals a rostrocaudal topographic organization of synergy encoding by the lumbar cord. Each synergy is preferentially activated from distinct regions, which may be multiple, and partially overlap between different synergies. Comparing the sequence of synergy activation in locomotion with their spinal cord topography suggests that the locomotor output is achieved by a rostrocaudally traveling wave of activation in the swing–stance cycle. A two-layer circuitry model, based on this topography and a traveling wave reproduces this output and explores its possible modifications under different afferent inputs. Our results and simulations suggest that a rostrocaudally traveling wave of excitation takes advantage of the topography of interneuronal regions encoding synergies, to activate them in the proper sequence for locomotion.National Institutes of Health (U.S.) (Grant NS 09343)Swiss National Science Foundatio

Neuronal Correlates of Motor Performance and Motor Learning in the Primary Motor Cortex of Monkeys Adapting to an External Force Field

AbstractThe primary motor cortex (M1) is known to control motor performance. Recent findings have also implicated M1 in motor learning, as neurons in this area show learning-related plasticity. In the present study, we analyzed the neuronal activity recorded in M1 in a force field adaptation task. Our goal was to investigate the neuronal reorganization across behavioral epochs (before, during, and after adaptation). Here we report two main findings. First, memory cells were present in two classes. With respect to the changes of preferred direction (Pd), these two classes complemented each other after readaptation. Second, for the entire neuronal population, the shift of Pd matched the shift observed for muscles. These results provide a framework whereby the activity of distinct neuronal subpopulations combines to subserve both functions of motor performance and motor learning

Critical Points and Traveling Wave in Locomotion: Experimental Evidence and Some Theoretical Considerations

The central pattern generator (CPG) architecture for rhythm generation remains partly elusive. We compare cat and frog locomotion results, where the component unrelated to pattern formation appears as a temporal grid, and traveling wave respectively. Frog spinal cord microstimulation with N-methyl-D-Aspartate (NMDA), a CPG activator, produced a limited set of force directions, sometimes tonic, but more often alternating between directions similar to the tonic forces. The tonic forces were topographically organized, and sites evoking rhythms with different force subsets were located close to the constituent tonic force regions. Thus CPGs consist of topographically organized modules. Modularity was also identified as a limited set of muscle synergies whose combinations reconstructed the EMGs. The cat CPG was investigated using proprioceptive inputs during fictive locomotion. Critical points identified both as abrupt transitions in the effect of phasic perturbations, and burst shape transitions, had biomechanical correlates in intact locomotion. During tonic proprioceptive perturbations, discrete shifts between these critical points explained the burst durations changes, and amplitude changes occurred at one of these points. Besides confirming CPG modularity, these results suggest a fixed temporal grid of anchoring points, to shift modules onsets and offsets. Frog locomotion, reconstructed with the NMDA synergies, showed a partially overlapping synergy activation sequence. Using the early synergy output evoked by NMDA at different spinal sites, revealed a rostrocaudal topographic organization, where each synergy is preferentially evoked from a few, albeit overlapping, cord regions. Comparing the locomotor synergy sequence with this topography suggests that a rostrocaudal traveling wave would activate the synergies in the proper sequence for locomotion. This output was reproduced in a two-layer model using this topography and a traveling wave. Together our results suggest two CPG components: modules, i.e., synergies; and temporal patterning, seen as a temporal grid in the cat, and a traveling wave in the frog. Animal and limb navigation have similarities. Research relating grid cells to the theta rhythm and on segmentation during navigation may relate to our temporal grid and traveling wave results. Winfree’s mathematical work, combining critical phases and a traveling wave, also appears important. We conclude suggesting tracing, and imaging experiments to investigate our CPG model

BimodalGaze:Seamlessly Refined Pointing with Gaze and Filtered Gestural Head Movement

Eye gaze is a fast and ergonomic modality for pointing but limited in precision and accuracy. In this work, we introduce BimodalGaze, a novel technique for seamless head-based refinement of a gaze cursor. The technique leverages eye-head coordination insights to separate natural from gestural head movement. This allows users to quickly shift their gaze to targets over larger fields of view with naturally combined eye-head movement, and to refine the cursor position with gestural head movement. In contrast to an existing baseline, head refinement is invoked automatically, and only if a target is not already acquired by the initial gaze shift. Study results show that users reliably achieve fine-grained target selection, but we observed a higher rate of initial selection errors affecting overall performance. An in-depth analysis of user performance provides insight into the classification of natural versus gestural head movement, for improvement of BimodalGaze and other potential applications

Polymer Fiber Probes Enable Optical Control of Spinal Cord and Muscle Function In Vivo

Restoration of motor and sensory functions in paralyzed patients requires the development of tools for simultaneous recording and stimulation of neural activity in the spinal cord. In addition to its complex neurophysiology, the spinal cord presents technical challenges stemming from its flexible fibrous structure and repeated elastic deformation during normal motion. To address these engineering constraints, we developed highly flexible fiber probes, consisting entirely of polymers, for combined optical stimulation and recording of neural activity. The fabricated fiber probes exhibit low-loss light transmission even under repeated extreme bending deformations. Using our fiber probes, we demonstrate simultaneous recording and optogenetic stimulation of neural activity in the spinal cord of transgenic mice expressing the light sensitive protein channelrhodopsin 2 (ChR2). Furthermore, optical stimulation of the spinal cord with the polymer fiber probes induces on-demand limb movements that correlate with electromyographical (EMG) activity.National Science Foundation (U.S.) (EEC-1028725)National Science Foundation (U.S.) (Career Award)National Science Foundation (U.S.) (DMR-0819762)McGovern Institute for Brain Research at MIT (Neurotechnology Grant)Massachusetts Institute of Technology. Simons Center for the Social Brai

Eye&Head:Synergetic Eye and Head Movement for Gaze Pointing and Selection

Eye gaze involves the coordination of eye and head movement to acquire gaze targets, but existing approaches to gaze pointing are based on eye-tracking in abstraction from head motion. We propose to leverage the synergetic movement of eye and head, and identify design principles for Eye&Head gaze interaction. We introduce three novel techniques that build on the distinction of head-supported versus eyes-only gaze, to enable dynamic coupling of gaze and pointer, hover interaction, visual exploration around pre-selections, and iterative and fast confirmation of targets. We demonstrate Eye&Head interaction on applications in virtual reality, and evaluate our techniques against baselines in pointing and confirmation studies. Our results show that Eye&Head techniques enable novel gaze behaviours that provide users with more control and flexibility in fast gaze pointing and selection