Bioelectronic devices should optimally merge a soft, biocompatible tissue interface with capacity for local, advanced signal processing. Here, we introduce an organic mixed-conducting particulate composite material (MCP) that can form functional electronic components by varying particle size and density. We created MCP-based high-performance anisotropic films, independently addressable transistors, resistors, and diodes that are pattern free, scalable, and biocompatible. MCP enabled facile and effective electronic bonding between soft and rigid electronics, permitting recording of neurophysiological data at the resolution of individual neurons from freely moving rodents and from the surface of the human brain through a small opening in the skull. We also noninvasively acquired high–spatiotemporal resolution electrophysiological signals by directly interfacing MCP with human skin. MCP provides a single-material solution to facilitate development of bioelectronic devices that can safely acquire, transmit, and process complex biological signals.

Chitosan (CS) is a biocompatible, inexpensive organic polymer that is increasingly used in neural tissue applications. However, its intrinsic fluorescence has not yet been leveraged to facilitate localization of neural interface devices, a key procedure to ensure accurate analysis of neurophysiological signals. A process is developed to enable control of mechanical and chemical properties of CS‐based composites, generating freestanding films that are stable in aqueous environments and exhibit concentration‐dependent fluorescence intensity. The shape and location of CS‐coated probes are reliably visualized in vitro and in vivo using fluorescence microscopy. Furthermore, CS neural probe marking is fully compatible with classical immunohistochemical and histological techniques, enabling localization of high spatiotemporal resolution surface electrocorticography arrays in adult rats and mouse pups. CS composites have the potential to simplify and streamline experimental procedures required to efficiently acquire, localize, and interpret neurophysiological data.

Acquisition, processing, and manipulation of biological signals require transistor circuits capable of ion to electron conversion. However, use of this class of transistors in integrated sensors or circuits is limited due to difficulty in patterning biocompatible electrolytes for independent operation of transistors. It is hypothesized that it would be possible to eliminate the need for electrolyte patterning by enabling directional ion conduction as a property of the material serving as electrolyte. Here, the anisotropic ion conductor (AIC) is developed as a soft, biocompatible composite material comprised of ion‐conducting particles and an insulating polymer. AIC displays strongly anisotropic ion conduction with vertical conduction comparable to isotropic electrolytes over extended time periods. AIC allows effective hydration of conducting polymers to establish volumetric capacitance, which is critical for the operation of electrochemical transistors. AIC enables dense patterning of transistors with minimal leakage using simple solution‐based deposition techniques. Lastly, AIC can be utilized as a dry, anisotropic interface with human skin that is capable of non‐invasive acquisition of individual motor action potentials. The properties of AIC position it to enable implementation of a wide range of large‐scale organic bioelectronics and enhance their translation to human health applications.

Reactivation of long-term memories enables experience-dependent strengthening, weakening, or updating of memory traces. Although coupling of hippocampal and cortical activity patterns facilitates initial memory consolidation, whether and how these patterns are involved in postreactivation memory processes are not known. Here, we monitored the hippocampal–cortical network as rats repetitively learned and retrieved spatial and nonspatial memories. We show that interactions between hippocampal sharp wave–ripples (SPW-R), cortical spindles (SPI), and cortical ripples (CXR) are jointly modulated in the absence of memory demand but independently recruited depending on the stage of memory and task type. Reconsolidation of memory after retrieval is associated with an increased and extended window of coupling between hippocampal SPW-Rs and CXRs compared to the initial consolidation. Hippocampal SPW-R and cortical spindle interactions are preferentially engaged during memory consolidation. These findings suggest that specific, time-limited patterns of oscillatory coupling can support the distinct memory processes required to flexibly manage long-term memories in a dynamic environment.