Beyond the straight path: high-density laminar recordings in the ventral hippocampus with curved microprobes

Abstract

Neural circuits are organized within complex three-dimensional architectures. Most neural interfaces follow linear insertion trajectories, limiting their ability to achieve laminar recording in brain regions where neuronal layers lie approximately parallel to the insertion path. Here, we introduce a curved flexible neural interface that enables near-perpendicular alignment of the recording sites with the targeted neuronal layers. The device consists of a flexible Parylene-C neural probe, integrating 16 PEDOT:BF4-coated Au microelectrodes and a transient silk fibroin stiffener for controlled implantation. The electrodes exhibit low impedance at 1 kHz (29.2 {+/-} 2.5 k{Omega}) and were accurately positioned across the layers of the ventral hippocampus using a rotational implantation strategy. Chronic in vivo recordings demonstrate stable electrochemical performance and reliable acquisition of local field potentials over four weeks. This work establishes a strategy for anatomically matched neural interfacing, enabling high-resolution investigation of neural circuits that are challenging to study with conventional linear probes.