The rodent whisker system is a major model for understanding neural mechanisms for tactile sensation of surface texture (roughness). Rats discriminate surface texture using the whiskers, and several theories exist for how texture information is physically sensed by the long, moveable macrovibrissae and encoded in spiking of neurons in somatosensory cortex. However, evaluating these theories requires a psychometric curve for texture discrimination, which is lacking. Here we trained rats to discriminate rough vs. fine sandpapers and grooved vs. smooth surfaces. Rats intermixed trials at macrovibrissa contact distance (nose >2 mm from surface) with trials at shorter distance (nose <2 mm from surface). Macrovibrissae were required for distant contact trials, while microvibrissae and non-whisker tactile cues were used for short distance trials. A psychometric curve was measured for macrovibrissa-based sandpaper texture discrimination. Rats discriminated rough P150 from smoother P180, P280, and P400 sandpaper (100, 82, 52, and 35 µm mean grit size, respectively). Use of olfactory, visual, and auditory cues was ruled out. This is the highest reported resolution for rodent texture discrimination, and constrains models of neural coding of texture information.

Due to the complicated artefacts in SIMS depth profiling, SIMS depth resolution is difficult to evaluate. For evaluation of the SIMS depth resolution, delta-doped layers are more useful than sharp interfaces, because the matrix effect and the sputtering rate change can be minimized in profiling through delta layers. The GaAs delta-doped layers in Si were grown and proposed as a reference material for the evaluation of SIMS depth resolution. The SIMS depth resolution was estimated using the analytical expression based on a double exponential with a Gaussian, and its dependence on SIMS analysis conditions such as ion energy, ion species and incidence angle was studied with the proposed GaAs delta-doped multilayers in Si.

The GenBank accession numbers for the 16S rRNA gene sequence of strains MMS17-SY117 T , MMS17-SY207-3 T and MMS17-SY213 T are MH166741, EF363712 and MH166742, and those for their whole-genome sequences are CP038267, CP038436 and SRRO00000000, respectively. Those of raw data in the SRA database are SRR8573677, SRR8797226 and SRR8801857, respectively. Four supplementary tables and two supplementary figures are available with the online version of this article.

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