A Miniaturized System for Spike-Triggered Intracortical Microstimulation in an Ambulatory Rat

Abstract

This paper reports on a miniaturized system for spike-triggered intracortical microstimulation (ICMS) in an ambulatory rat. The head-mounted microdevice comprises a previously developed application-specific integrated circuit fabricated in 0.35-μm two-poly four-metal complementary metal-oxide-semiconductor technology, which is assembled and packaged on a miniature rigid-flex substrate together with a few external components for programming, supply regulation, and wireless operation. The microdevice operates autonomously from a single 1.55-V battery, measures 3.6 cm × 1.3 cm × 0.6 cm, weighs 1.7 g (including the battery), and is capable of stimulating as well as recording the neural response to ICMS in biological experiments with anesthetized laboratory rats. Moreover, it has been interfaced with silicon microelectrodes chronically implanted in the cerebral cortex of an ambulatory rat and successfully delivers electrical stimuli to the second somatosensory area when triggered by neural activity from the rostral forelimb area with a user-adjustable spike-stimulus time delay. The spike-triggered ICMS is further shown to modulate the neuronal firing rate, indicating that it is physiologically effective.

Restoration of function after brain damage using a neural prosthesis

“…After injury to the CFA, a recording microelectrode was placed in the RFA, whereas a stimulating microelectrode was placed in the distal forelimb field of S1. A BMBI discriminated action potentials in the RFA, and after a 7.5-ms delay, it delivered a low-level electrical current pulse to S1 (13). ( pairwise comparisons: P = 0.0891 for ADS vs. OLS, P = 0.0002 for ADS vs. control, and P = 0.0278 for OLS vs. control).…”

“…1 B and C). To this end, a microdevice was developed with the ability to deliver activity-dependent stimulation (ADS) through recording and digitizing extracellular neural activity from an implanted microelectrode, discriminating individual action potentials (spikes), and delivering small amounts of electrical current to another microelectrode implanted in a distant population of neurons (13,14). This closed-loop system was similar, in principle, to the "Neurochip" used previously by other investigators to demonstrate the effects of local ADS in intact animals (15), but it was miniaturized for head-mounted, wireless operation ( Fig.…”

Spontaneous cortical activity alternates between motifs defined by regional axonal projections

“…Studies of cortical connection structure [47][48][49] and function could be extended to animals that model disease. Investigators have begun to develop hardware to stimulate circuits that were lost due to ischemic damage 50 . Brain stimulation may be aided by knowledge of cortical functional connections leading to rationally designed stimulus paradigms that could be translated to patients using transcranial magnetic stimulations, transcranial direct current, or even optogenetics.…”

Implantable neurotechnologies: bidirectional neural interfaces—applications and VLSI circuit implementations

“…To enable this study, the authors created a custom device modeled after the Neurochip [85]. Azin et al designed an application-specific integrated circuit (ASIC) that contained recording and stimulating circuits as well as signal processing circuits implementing the algorithm described above [8,9]. …”