Neural interfaces are implanted devices that couple the nervous system to electronic circuitry. They are intended for long term use to control assistive technologies such as muscle stimulators or prosthetics that compensate for loss of function due to injury. Here we present a novel design of interface for peripheral nerves. Recording from axons is complicated by the small size of extracellular potentials and the concentration of current flow at nodes of Ranvier. Confining axons to microchannels of ~100 µm diameter produces amplified potentials that are independent of node position. After implantation of microchannel arrays into rat sciatic nerve, axons regenerated through the channels forming 'mini-fascicles', each typically containing ~100 myelinated fibres and one or more blood vessels. Regenerated motor axons reconnected to distal muscles, as demonstrated by the recovery of an electromyogram and partial prevention of muscle atrophy. Efferent motor potentials and afferent signals evoked by muscle stretch or cutaneous stimulation were easily recorded from the mini-fascicles and were in the range of 35-170 µV. Individual motor units in distal musculature were activated from channels using stimulus currents in the microampere range. Microchannel interfaces are a potential solution for applications such as prosthetic limb control or enhancing recovery after nerve injury.

ObjectivePatients with major depressive disorder (MDD) with inadequate response to antidepressant treatment (ADT) may suffer a prolonged loss of functioning. This review aimed to determine if self-rated functional measures are informative in randomized placebo-controlled studies of adjunctive therapy in patients with MDD and inadequate response to ADT.MethodsThis was a systematic literature review of articles in any language from the MEDLINE database published between January 1990 and March 2017. Eligible studies met the following criteria: patients with MDD; inadequate response to at least one ADT; adjunctive therapy (pharmacological or otherwise) to ADT; placebo control group; randomized controlled trial or a post hoc analysis of a randomized controlled trial; reported a self-rated functioning scale. Study characteristics and functioning efficacy data were extracted.ResultsA total of 2,090 discrete records were screened, 293 full-text articles were assessed for eligibility, and 26 studies were included. All studies were acute (6–12 weeks) except for one 52-week study. The only self-rated functioning scale used in the included studies was the Sheehan Disability Scale (SDS). Of the 13 adjunctive agents identified, aripiprazole, brexpiprazole, edivoxetine, and risperidone improved functioning versus placebo (p<0.05), as measured by the SDS total or mean score. On the SDS “work/studies” item, only aripiprazole had a statistically significant benefit, in one study out of four. Thus, where a benefit was observed on the SDS total or mean, this was generally driven by improvement on the “social life” and “family life” items. A limitation of the review is that it only considered published literature from one database.ConclusionThe SDS, a self-rated functional measure, is informative in acute randomized placebo-controlled studies of adjunctive therapy in patients with MDD and inadequate response to ADT. However, the item that measures work performance may be less relevant to this population than the items that measure social and family life.

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