Video summarization by group scoring

In this paper a new model for user-centered video summarization is presented. Involvement of more than one expert in generating the final video summary should be regarded as the main use case for this algorithm. This approach consists of three major steps. First, the video frames are scored by a group of operators. Next, these assigned scores are averaged to produce a singular value for each frame and lastly, the highest scored video frames alongside the corresponding audio and textual contents are extracted to be inserted into the summary. The effectiveness of this approach has been evaluated by comparing the video summaries generated by this system against the results from a number of automatic summarization tools that use different modalities for abstraction

Persistent positional nystagmus

Involvement of the superior semicircular canal (SSC) in benign paroxysmal positional vertigo (BPPV) is rare. SSC BPPV is distinguished from the more common posterior semicircular canal (PSC) variant by the pattern of nystagmus triggered by the Dix‐Hallpike position: down‐beating torsional nystagmus in SSC BPPV versus up‐beating torsional nystagmus in PSC BPPV. SSC BPPV may be readily treated at the bedside, which is a key component in excluding central causes of down‐beating nystagmus. We present an unusual video case report believed to represent refractory SSC BPPV based on the pattern of nystagmus and the absence of any other central signs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86936/1/21848_ftp.pd

Spatial integration during active tactile sensation drives orientation perception

Active haptic sensation is critical for object identification, but its neural circuit basis is poorly understood. We combined optogenetics, two-photon imaging, and high-speed behavioral tracking in mice solving a whisker-based object orientation discrimination task. We found that orientation discrimination required animals to summate input from multiple whiskers specifically along the whisker arc. Animals discriminated the orientation of the stimulus per se as their performance was invariant to the location of the presented stimulus. Populations of barrel cortex neurons summated across whiskers to encode each orientation. Finally, acute optogenetic inactivation of the barrel cortex and cell-type-specific optogenetic suppression of layer 4 excitatory neurons degraded performance, implying that infragranular layers alone are not sufficient to solve the task. These data suggest that spatial summation over an active haptic array generates representations of an object's orientation, which may facilitate encoding of complex three-dimensional objects during active exploration

Short Time-Scale Sensory Coding in S1 during Discrimination of Whisker Vibrotactile Sequences

<div><p>Rodent whisker input consists of dense microvibration sequences that are often temporally integrated for perceptual discrimination. Whether primary somatosensory cortex (S1) participates in temporal integration is unknown. We trained rats to discriminate whisker impulse sequences that varied in single-impulse kinematics (5–20-ms time scale) and mean speed (150-ms time scale). Rats appeared to use the integrated feature, mean speed, to guide discrimination in this task, consistent with similar prior studies. Despite this, 52% of S1 units, including 73% of units in L4 and L2/3, encoded sequences at fast time scales (≤20 ms, mostly 5–10 ms), accurately reflecting single impulse kinematics. 17% of units, mostly in L5, showed weaker impulse responses and a slow firing rate increase during sequences. However, these units did not effectively integrate whisker impulses, but instead combined weak impulse responses with a distinct, slow signal correlated to behavioral choice. A neural decoder could identify sequences from fast unit spike trains and behavioral choice from slow units. Thus, S1 encoded fast time scale whisker input without substantial temporal integration across whisker impulses.</p></div

Choice coding by slow time scale units.

<p>(A) Top: population PSTH (mean ± SEM) for Slow Positive units across all layers. Responses were indistinguishable between FFF, FMS, SMF and SSS trains. Bottom: population PSTH for individual F, M, and S impulses, irrespective of sequence membership. (B) Population PSTH for slow negative units, showing lack of any impulse-evoked firing rate modulation. (C) Population PSTH for slow positive units in L5a and L5b, separated by stimulus type and drink port choice. Slow Positive units fired more on right-choice trials for all stimuli. (D) Difference in evoked rate between right- and left-choice trials, measured 5–50 ms after start of the final impulse, for all Slow Positive units (left) or Fast and Medium units (right). Number of units in each layer is shown at bottom. Open symbols, baseline rate before sequence onset for the same trials. * <i>p</i> = 0.022; ** <i>p</i> = 9.5 x 10^-4; *** <i>p</i> = 7.5 x 10^-5, paired <i>t</i> test comparing rate on right versus left choice trials. (E) Population PSTH averaged across all four sequences, for right- versus left-choice trials, for Slow Positive units in L5 (top), and for Fast units in L4 (bottom). Bar shows times when rate is significantly different between right- and left-choice trials by sliding <i>t</i> test (<i>p</i> < 0.05). The distribution of nose poke withdrawal times is shown for the same trials. Data for this figure are at <a href="http://crcns.org" target="_blank">crcns.org</a> repository (accession ssc-4).</p

Sequence responses for example units.

<p>(A and B) L4 multi-unit and L5b RS single unit with phasic response to each impulse. (C and D) L6 multi-unit and L5b RS single unit with increasing firing rate during the stimulus period. Each panel shows the spike raster and PSTH across trials, for one stimulus sequence. Vertical lines: onset of each impulse. Data for this figure are at <a href="http://crcns.org" target="_blank">crcns.org</a> repository (accession ssc-4).</p

Stimulus coding by fast time scale units.

<p>(A) Population PSTH (mean ± SEM) for Fast units with 5, 10, and 15–20 ms best integration windows. (B) Population PSTH for all individual F, M, or S impulses, irrespective of sequence membership, for all Fast units. Dashed line: pre-impulse firing rate. (C) Left: net evoked rate for individual impulses, calculated as post-impulse rate–pre-impulse rate. Right: mean rate across the entire sequence above pre-stimulus baseline, as a function of mean panel speed. Symbols show mean ± SEM across units. Line: regression. (D) Population PSTH for Medium units for FFF, FMS, SMF, and SSS sequences. (E) Net evoked rate for individual impulses and mean rate across the sequence for Medium units. Conventions as in C. Firing rate was suppressed by all impulses and sequences. Data for this figure are at <a href="http://crcns.org" target="_blank">crcns.org</a> repository (accession ssc-4).</p