FPGA Design Integration of a 32-Microelectrodes Low-Latency Spike Detector in a Commercial System for Intracortical Recordings
, Marta Bisio 2, Marta Maschietto 2, Alessandro Leparulo 2 and Stefano Vassanelli 1,2
Round 1
Reviewer 1 Report
The manuscript entitled "FPGA design integration of a 32-microelectrodes low-latency spike detector in a commercial system for intracortical recordings" demonstrated a design for sub-millisecond detection and communication of the spiking activity detected by an array of 32 intracortical microelectrodes. Overall, it is well organzied. I suggest authors to add some physical or application figures of the chip to the best interest of readers.
Author Response
Thank you for the time spent to review the document and for the feedback.
You suggested to add some physical or application figures of the chip to the best interest of readers.
We added 3 new image showing both the application and the devices used. Figure 1 shows the recording system, Figure 8 display the application GUI and Figure 9 illustrates the probe used to record.
Reviewer 2 Report
In this paper, a design for sub-millisecond detection and communication of the spiking activity detected by an array of intracortical microelectrodes is presented, exploiting the real-time processing provided by FPGAs. It is very good.
But, I also have the following questions:
1, The description of the animals examined in this paper is not clear.
2, If the authors can compare the detection effect of the system designed in this paper with that of other systems, it will be better.
Author Response
Thank you for the time spent to review the document, the feedback and for the questions. Below the points are reported and then addressed.
Point 1: The description of the animals examined in this paper is not clear.
Response 1: details have been added to the "Animals and surgical procedure" section (2.3). Line 106 and 382 now anticipate and clarify that experiments are performed on barrel cortex of rats.
Point 2: If the authors can compare the detection effect of the system designed in this paper with that of other systems, it will be better.
Response 2: Table 5 has been added accompanied by paragraph from line 506 to 509, comparing the performances of the system with that of three others similar recent devices.
Reviewer 3 Report
This paper presents a design for the detection and communication of the neural spiking activity detected by an array of intracortical microelectrodes. The design uses FPGA for real-time processing and low latency response. The paper is very well written and structured, with clear and valuable contributions. I only have minor concerns: 1) The literature review could be enhanced; and 2) A conclusion section should be provided at the end of the paper.
Author Response
Thank you for the time spent to review the document and the feedback. Below the points are reported and then addressed.
Point 1: The literature review could be enhanced.
Response 1: We added new references to recent literature specially in the Introduction (1-3, 9-12, 15-17, 22-25, 29, 30).
Point 2: A conclusion section should be provided at the end of the paper.
Response 2: We added the Conclusion section, where we moved part of the Discussion and we added a summary of the work.
Reviewer 4 Report
The authors reported a FPGA-based design for low-latency spike detection and intracortical microstimulation. Although the study is interesting, the authors need to clarify the following points for a publication. Most issues link to the animal experiments.
- In Figures 7 and 9, clarify exactly what determined the timing of ICMSs. It does not seem to be locked to spike timing or a MUA event. This leads to a question about the system’s performance/capability.
- The section 2.3 is needed to elaborate. Several rats seemed to be used. But how many? In addition, describe exactly how the system was implemented for in vivo experiments and how ICMSs were applied (this relates to the first point).
- In Figure 9, if several rats were used, provide statistics for a reproducibility purpose. How often did the authors observe spindle-like activity after ICMSs? If LFPs were also recorded, the authors can compare spectral contents before and after ICMSs.
Author Response
Thank you for the time spent to review the document and the feedback. Below the points are reported and then addressed.
Point 1: In Figures 7 and 9, clarify exactly what determined the timing of ICMSs. It does not seem to be locked to spike timing or a MUA event. This leads to a question about the system’s performance/capability.
Response 1: The ICMS timing depend on the stimulation protocol. We addressed it from line 393 to line 395 and we highlighted it until line 397.
Point 2: The section 2.3 is needed to elaborate. Several rats seemed to be used. But how many? In addition, describe exactly how the system was implemented for in vivo experiments and how ICMSs were applied (this relates to the first point).
Response 2: We detailed Section 2.3, while we should have answered to the ICMS protocol and the number of rats with the fix from of the previous point.
Point 3: In Figure 9, if several rats were used, provide statistics for a reproducibility purpose. How often did the authors observe spindle-like activity after ICMSs? If LFPs were also recorded, the authors can compare spectral contents before and after ICMSs.
Response 3: We added the Details about the evoked response from line 442 to line 446 and we updated Figure 12 (ex 9) with both LFP and high-pass filtered traces to provide more details according with the text.
We hope we provided the details about the activity evoked by the ICMS required to understand the quality of the MUA detection of our system. We hope also to not go out of the scope of our presentation of the spike detector technical implementation, that is the predominant topic of this work. Anyway, further details about the ICMS evoked response are still under our investigation as well as the activity dependent ICMS.
Round 2
Reviewer 4 Report
The authors have addressed all of my initial concerns. The current version is suitable for a publication.
Author Response
Thank you for the kind review.
Best regards.
