Packages and the Recording Chain

Probe Package

A probe package is a purpose-designed sub-assembly permanently integrated with a silicon probe during production. It provides the connector, insulating materials, circuit board, and mechanical structure needed to handle and use the probe.

Why it matters: The package determines how a probe connects to a headstage, how it mounts to a stereotaxic frame or chronic implant, and what accessories (cables, adapters, commutators) are needed. Package choice is one of the most important decisions in experiment planning.

Key components: Standard connector (Omnetics, ZIF-Clip, uHDMI), miniaturized PCB, insulating body, and optional features like chronic mounting hardware, drive compatibility, or drug delivery channels.

Note: Probe packages are not stand-alone products — they are part of a fully assembled, ready-to-use probe. The package family (A-series, Activus, Chronic Microdrive, etc.) is selected at ordering time.

MR-Compatible Package Series

Eleven builds across the A-Series, Chronic Microdrive, Hybrid and Optrode series, 16 to 64 channels, on the non-magnetic MRI Omnetics connector. Records and stimulates. The assembly neither distorts the field nor heats in it. MR builds sit inside the series they are variants of — MRA16 alongside A16 — rather than forming a series of their own, and the choice is fixed at order.

Research use only.

Optrode Package Series

An optrode package adds an optical fiber to a probe package, so light is delivered on the same trajectory as the recording sites. It is a build option on a package family, not a family of its own.

Optrode builds exist across the A-Series, CM, Hybrid, ZIF, Q-Trode, Vector, drug-delivery and Activus SiNAPS families, and each is documented in its own family entry. The fiber is fitted at assembly; the probe, connector and cable are whatever the base family specifies.

Two things follow on every optrode — the fiber adds cross-section along the whole trajectory, and light reaches the electrodes too, so plan the analysis window around a photoelectric artifact at onset.

Research use only.

Optogenetics

Optogenetics uses light to control neurons that have been genetically modified to express light-sensitive proteins (opsins), enabling precise temporal and spatial manipulation of neural circuits.

Why it matters: Optogenetics allows researchers to selectively activate or silence specific neuron types with millisecond precision, establishing causal links between neural activity and behavior that correlational methods cannot provide.

Combined with recording: Optoelectrode probes integrate light delivery (via optical fibers or waveguides) with electrical recording sites on a single device, enabling simultaneous stimulation and recording without separate implants.

Key proteins: Channelrhodopsin-2 (ChR2) for excitation, halorhodopsin (NpHR) for inhibition, and newer variants with improved kinetics, sensitivity, and spectral properties.

NeuroNexus products: Optoelectrode probes combine silicon recording arrays with integrated optical fibers for combined optogenetic stimulation and multi-site recording.

Headstage

A headstage (also called a preamplifier) is a compact electronic module that provides first-stage amplification and signal conditioning for neural signals, positioned as close as possible to the recording electrodes.

Why it matters: Neural signals are extremely small (50–500 µV) and susceptible to noise. By amplifying signals at the source — before they travel through long cables — headstages dramatically improve signal-to-noise ratio and reduce artifacts.

Key specifications: Input noise (typically <2 µV RMS), channel count, gain, bandwidth, digital interface (SPI, LVDS, uHDMI), weight (critical for freely moving experiments), and connector type.

In the signal chain: Headstages sit between the probe package connector and the data acquisition system (DAQ), forming the second link in the signal chain: probe → package → headstage → DAQ.

See the Neural Recording Chips Guide for details on the semiconductor ASICs embedded in NeuroNexus headstages.

Microdrive

A microdrive is a mechanical device that allows precise adjustment of probe depth in small increments (typically 25–100 µm per step) during intra-operative insertion or after chronic implantation.

Why it matters: Microdrives enable targeting of specific brain layers and recovery from tissue settling that occurs after initial insertion. In chronic experiments, they allow repositioning to find new neurons after initial units are lost.

Types: Manual screw-driven (most common for chronic), motorized (for automated positioning during acute experiments), and multi-probe drives that independently position multiple shanks.

NeuroNexus products: The Chronic Microdrive package integrates a microdrive mechanism directly into the probe package, providing a compact, implantable system for depth adjustment in freely moving animals.

Commutator

A commutator (also called a slip ring or swivel) is a rotary electrical connector that prevents cable twisting during freely moving recordings by allowing continuous 360° rotation.

Why it matters: In chronic freely moving experiments, animals turn and move continuously. Without a commutator, the cable between the headstage and DAQ system would twist, eventually breaking connections or exerting torque on the implant.

Types: Passive (mechanical slip rings) and active/motorized (servo-controlled rotation that tracks the animal's turning, reducing torque to near zero).

NeuroNexus products: The Alpha commutator provides motorized, zero-torque cable management for freely moving neural recordings.