A Neuromorphic Prosthesis to Restore Communication in Neuronal Networks.

Recent advances in bioelectronics and neural engineering allowed the development of brain machine interfaces and neuroprostheses, capable of facilitating or recovering functionality in people with neurological disability. To realize energy-efficient and real-time capable devices, neuromorphic computing systems are envisaged as the core of next-generation systems for brain repair. We demonstrate here a real-time hardware neuromorphic prosthesis to restore bidirectional interactions between two neuronal populations, even when one is damaged or missing.

Mechano-sensitization of mammalian neuronal networks through expression of the bacterial large-conductance mechanosensitive ion channel.

Development of remote stimulation techniques for neuronal tissues represents a challenging goal. Among the potential methods, mechanical stimuli are the most promising vectors to convey information non-invasively into intact brain tissue. In this context, selective mechano-sensitization of neuronal circuits would pave the way to develop a new cell-type-specific stimulation approach.

Modulation of Neural Network Activity through Single Cell Ablation: An in Vitro Model of Minimally Invasive Neurosurgery.

The technological advancement of optical approaches, and the growth of their applications in neuroscience, has allowed investigations of the physio-pathology of neural networks at a single cell level. Therefore, better understanding the role of single neurons in the onset and progression of neurodegenerative conditions has resulted in a strong demand for surgical tools operating with single cell resolution. Optical systems already provide subcellular resolution to monitor and manipulate living tissues, and thus allow understanding the potentiality of surgery actuated at single cell level.

Laser Nano-Neurosurgery from Gentle Manipulation to Nano-Incision of Neuronal Cells and Scaffolds: An Advanced Neurotechnology Tool.

Current optical approaches are progressing far beyond the scope of monitoring the structure and function of living matter, and they are becoming widely recognized as extremely precise, minimally-invasive, contact-free handling tools. Laser manipulation of living tissues, single cells, or even single-molecules is becoming a well-established methodology, thus founding the onset of new experimental paradigms and research fields. Indeed, a tightly focused pulsed laser source permits complex tasks such as developing engineered bioscaffolds, applying calibrated forces, transfecting, stimulating, or even ablating single cells with subcellular precision, and operating intracellular surgical protocols at the level of single organelles.

Cofilin 1 activation prevents the defects in axon elongation and guidance induced by extracellular alpha-synuclein.

Impaired adult neurogenesis and axon traumatic injury participate in the severity of neurodegenerative diseases. Alpha-synuclein, a cytosolic protein involved in Parkinson's disease, may be released from neurons, suggesting a role for excess secreted alpha-synuclein in the onset and spread of the pathology. Here we provide evidence that long term exposure of young neurons to extracellular alpha-synuclein hampers axon elongation and growth cone turning.

A microchannel device tailored to laser axotomy and long-term microelectrode array electrophysiology of functional regeneration.

We designed a miniaturized and thin polydimethylsiloxane (PDMS) microchannel device compatible with commercial microelectrode array (MEA) chips. It was optimized for selective axonal ablation by laser microdissection (LMD) to investigate the electrophysiological and morphological responses to a focal injury in distinct network compartments over 45 days in vitro (45 DIV). Low-density cortical or hippocampal networks (<3500 neurons per device) were cultured in quasi-closed somal chambers.

The biophysics of piezo1 and piezo2 mechanosensitive channels.

The ability to sense mechanical stimuli and elaborate a response to them is a fundamental process in all organisms, driving crucial mechanisms ranging from cell volume regulation up to organ development or regeneration. Nevertheless, only in few cases the underlying molecular players are known. In particular, mammals possess a large variety of mechanoreceptors, providing highly specialized functions in sensory cells, but also several housekeeping molecular systems are involved in the complex mechanism of mechanotransduction.

HDAC6 and RhoA are novel players in Abeta-driven disruption of neuronal polarity.

Maintenance of neuronal polarity and regulation of cytoskeletal dynamics are vital during development and to uphold synaptic activity in neuronal networks. Here we show that soluble β-amyloid (Aβ) disrupts actin and microtubule (MT) dynamics via activation of RhoA and inhibition of histone deacetylase 6 (HDAC6) in cultured hippocampal neurons. The contact of Aβ with the extracellular membrane promotes RhoA activation, leading to growth cone collapse and neurite retraction, which might be responsible for hampered neuronal pathfinding and migration in Alzheimer's disease (AD).

Involvement of microtubular network and its motors in productive endocytic trafficking of mouse polyomavirus.

Infection of non-enveloped polyomaviruses depends on an intact microtubular network. Here we focus on mouse polyomavirus (MPyV). We show that the dynamics of MPyV cytoplasmic transport reflects the characteristics of microtubular motor-driven transport with bi-directional saltatory movements.

Motility flow and growth-cone navigation analysis during in vitro neuronal development by long-term bright-field imaging.

A long-term live-imaging workstation to follow the development of cultured neurons during the first few days in vitro (DIV) is developed. In order to monitor neuronal polarization and axonal growth by live imaging, we built a micro-incubator system that provides stable temperature, pH, and osmolarity in the culture dish under the microscope, while preserving environment sterility. We are able to image living neurons at 2 DIVs for 48 h with a temporal resolution of one frame for every 2 min.

Long-term optical stimulation of channelrhodopsin-expressing neurons to study network plasticity.

Neuronal plasticity produces changes in excitability, synaptic transmission, and network architecture in response to external stimuli. Network adaptation to environmental conditions takes place in time scales ranging from few seconds to days, and modulates the entire network dynamics. To study the network response to defined long-term experimental protocols, we setup a system that combines optical and electrophysiological tools embedded in a cell incubator.

Measurement of tension release during laser induced axon lesion to evaluate axonal adhesion to the substrate at piconewton and millisecond resolution.

The formation of functional connections in a developing neuronal network is influenced by extrinsic cues. The neurite growth of developing neurons is subject to chemical and mechanical signals, and the mechanisms by which it senses and responds to mechanical signals are poorly understood. Elucidating the role of forces in cell maturation will enable the design of scaffolds that can promote cell adhesion and cytoskeletal coupling to the substrate, and therefore improve the capacity of different neuronal types to regenerate after injury.

Cell signaling experiments driven by optical manipulation.

Cell signaling involves complex transduction mechanisms in which information released by nearby cells or extracellular cues are transmitted to the cell, regulating fundamental cellular activities. Understanding such mechanisms requires cell stimulation with precise control of low numbers of active molecules at high spatial and temporal resolution under physiological conditions. Optical manipulation techniques, such as optical tweezing, mechanical stress probing or nano-ablation, allow handling of probes and sub-cellular elements with nanometric and millisecond resolution.

In vitro large-scale experimental and theoretical studies for the realization of bi-directional brain-prostheses.

Brain-machine interfaces (BMI) were born to control "actions from thoughts" in order to recover motor capability of patients with impaired functional connectivity between the central and peripheral nervous system. The final goal of our studies is the development of a new proof-of-concept BMI-a neuromorphic chip for brain repair-to reproduce the functional organization of a damaged part of the central nervous system. To reach this ambitious goal, we implemented a multidisciplinary "bottom-up" approach in which in vitro networks are the paradigm for the development of an in silico model to be incorporated into a neuromorphic device.

The formation of actin waves during regeneration after axonal lesion is enhanced by BDNF.

During development, axons of neurons in the mammalian central nervous system lose their ability to regenerate. To study the regeneration process, axons of mouse hippocampal neurons were partially damaged by an UVA laser dissector system. The possibility to deliver very low average power to the sample reduced the collateral thermal damage and allowed studying axonal regeneration of mouse neurons during early days in vitro.

Combined optical tweezers and laser dissector for controlled ablation of functional connections in neural networks.

Regeneration of functional connectivity within a neural network after different degrees of lesion is of utmost clinical importance. To test pharmacological approaches aimed at recovering from a total or partial damage of neuronal connections within a circuit, it is necessary to develop a precise method for controlled ablation of neuronal processes. We combined a UV laser microdissector to ablate neural processes in vitro at single neuron and neural network level with infrared holographic optical tweezers to carry out force spectroscopy measurements.

Simultaneous two-photon imaging and photo-stimulation with structured light illumination.

Holographic microscopy is increasingly recognized as a promising tool for the study of the central nervous system. Here we present a "holographic module", a simple optical path that can be combined with commercial scanheads for simultaneous imaging and uncaging with structured two-photon light. The present microscope is coupled to two independently tunable lasers and has two principal configurations: holographic imaging combined with galvo-steered uncaging and holographic uncaging combined with conventional scanning imaging.

Force generation in lamellipodia is a probabilistic process with fast growth and retraction events.

Polymerization of actin filaments is the primary source of motility in lamellipodia and it is controlled by a variety of regulatory proteins. The underlying molecular mechanisms are only partially understood and a precise determination of dynamical properties of force generation is necessary. Using optical tweezers, we have measured with millisecond (ms) temporal resolution and picoNewton (pN) sensitivity the force-velocity (Fv) relationship and the power dissipated by lamellipodia of dorsal root ganglia neurons.

Imaging of mouse experimental melanoma in vivo and ex vivo by combination of confocal and nonlinear microscopy.

We investigated possibilities of the combination of the one- and two-photon excitation microscopy for examination of the experimental melanoma tissue in vivo, in mice under general anesthesia, and ex vivo on freshly harvested specimens. Our aim was to obtain sufficiently informative images of unstained tumor tissues and their modifications after hyperthermia treatment. The mouse experimental melanoma structure was studied and compared with normal tissue from the same animal by using confocal and nonlinear microscopy techniques based on (i) one-photon excitation (1PE) fluorescence, (ii) 1PE reflectance, (iii) second harmonic generation imaging, and (iv) two-photon excitation autofluorescence.

Properties of the force exerted by filopodia and lamellipodia and the involvement of cytoskeletal components.

During neuronal differentiation, lamellipodia and filopodia explore the environment in search for the correct path to the axon's final destination. Although the motion of lamellipodia and filopodia has been characterized to an extent, little is known about the force they exert. In this study, we used optical tweezers to measure the force exerted by filopodia and lamellipodia with a millisecond temporal resolution.

Creatine kinase binds more firmly to the M-band of rabbit skeletal muscle myofibrils in the presence of its substrates.

Creatine kinase (CK) (E.C. 2.

Mouse polyomavirus enters early endosomes, requires their acidic pH for productive infection, and meets transferrin cargo in Rab11-positive endosomes.

Mouse polyomavirus (PyV) virions enter cells by internalization into smooth monopinocytic vesicles, which fuse under the cell membrane with larger endosomes. Caveolin-1 was detected on monopinocytic vesicles carrying PyV particles in mouse fibroblasts and epithelial cells (33). Here, we show that PyV can be efficiently internalized by Jurkat cells, which do not express caveolin-1 and lack caveolae, and that overexpression of a caveolin-1 dominant-negative mutant in mouse epithelial cells does not prevent their productive infection.