48Recent advances in neurotechnology allow neurological impairments to be treated or 49 reduced by brain machine interfaces and neuroprostheses. To develop energy-efficient and 50 3 real-time capable devices, neuromorphic computing systems are envisaged as the core of 51 next-generation 'neurobiohybrid' systems for brain repair. We demonstrate here the first 52 exploitation of a neuromorphic prosthesis to restore bidirectional interactions between two 53 neuronal populations, even when one is damaged or completely missing. We used in vitro 54 modular cell cultures to mimic the mutual interaction between neuronal assemblies and 55 created a focal lesion to functionally disconnect the two populations. Then, we employed 56 our neuromorphic prosthesis for two specific applications with future clinical 57 implications: bidirectional bridging to artificially reconnect two disconnected neuronal 58 modules and hybrid bidirectional bridging to replace the activity of one module with a 59 neuromorphic spiking neural network. Our neuroprosthetic system opens up new avenues 60 for the development of novel bioelectrical therapeutics for human applications. 61 62 65 the greatest impact carried by stroke (1) and traumatic brain injury (2), brain disorders are among 66 the leading causes of disabilities worldwide. Due to recent advances in neural and neuromorphic 67 engineering, direct interfacing of artificial circuits with large neuronal networks is possible to 68 develop novel 'neurobiohybrid' systems (such as neuroprostheses (3)), which are envisaged as 69 potentially interesting clinical applications for brain lesions (4). In this paper, we introduce an 70 innovative neuroprosthetic system based on a neuromorphic real-time interface that can re-71 establish the communication between two disconnected neuronal assemblies. 72 Neural interfaces are promising solutions for brain repair (5). Modern neural interfaces are mainly 73 designed to restore lost motor functions in only one direction, i.e., from the brain to the body (6) 74 or from the body to the brain (7). Additionally, recent neuroprosthetic developments have shown 75 4 the enormous potential of neural interfaces to aid and accelerate functional recovery (8, 9). 76 However, a major obstacle in developing novel neuroprosthetic devices for bidirectional 77 communication with and within the brain is the complex nature of interactions among different 78 brain areas, which in turn presents a challenge for the development of appropriate stimulation 79 protocols as well as for testing such devices using in vivo models (10). 80 Despite very recent technological progress (11, 12), in vivo models still have two main 81 bottlenecks. The first bottleneck is the technical challenge to faithfully reproduce specific/focal 82 network lesions (mainly due to their complexity) that the neuroprosthesis aims to treat, whereas 83 the second is the difficulty in disentangling the actual effect of the adopted electrical therapy from 84 the complex activity of a brain constantly pr...