Chronic animal DOT study

The 2024 study tested DOT cortical stimulators above intact dura in freely behaving pigs. Results report motor responses through 20-35 days in three stimulated animals. The article’s 30-day headline is not a uniform follow-up duration for every animal.

Cohorts are not interchangeable

Methods describes eight pigs and ten implants in four two-pig cohorts. The first two cohorts tested feasibility, handling and electrode design without chronic stimulation. They led to changes in the burr-hole cover and from bottom-only bipolar contacts to top/bottom pseudo-monopolar contacts.

In cohort three, one animal was a sham and one received stimulation. In cohort four, each animal received one active implant over left motor cortex and one sham over right motor cortex. Thus eight animals or ten implants must not be reported as eight or ten chronic stimulation successes.

The paper’s supplementary Table S1 was not accessible in this catalog pass. Exact per-animal durations and any additional table-only outcomes are not reconstructed from the summary.

Motor response and impedance

Animals received a 14-mm burr hole, silicone spacer and PEEK cover without direct cortical contact. Daily testing placed the external driver over the implant after the animal rested. This is externally powered stimulation, not continuous autonomous treatment.

Movement videos were compared after 7-V and 14-V stimulation. Changing camera distance and angle made absolute movements hard to compare across days; values were normalized to each day’s minimum and maximum. The reported within-day differences do not establish a constant absolute response for a month.

Impedance tracking used diagnostic backscatter in one animal, not all three stimulated animals. Resistance rose from about 1 to 2.25 kΩ between days 15 and 25, alongside lower movement amplitude at maximum voltage, then stabilized. Only measurements with successful calibration at all three tested voltages were included. This is not a complete packet-loss or unconditional telemetry-success dataset.

Stimulation dose and pathology

The study applied iTBS-like electrical stimulation for 300 minutes and 54,300 pulses in one animal, with 170 and 200 minutes in the other two. Devices were removed and animals survived another 7-10 days before tissue analysis. The paper reports no serious pathology in stimulated areas, with minor inflammatory responses in some active and sham cases. A reported active/sham comparison in one animal pair is not universal absence of foreign-body response.

The animals sometimes slept through stimulation, but the authors explicitly reserve sensory-percept assessment for chronic human studies. No pain-free human-use claim follows from that observation.

What remains open

This study does not demonstrate depression treatment, closed-loop neural sensing, multi-year hermetic survival or chronic human safety. The two intraoperative human tests remain temporary proof of motor activation.

Primary source

• Published full manuscript, 2024, chronic Results, Figure 5, cohort Methods, video analysis and impedance measurement.