Encoding speech sequence probability in human temporal cortex→

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In my quick first pass, this seems like a nice demonstration of phonotactic probability (likelihood of auditory transitions) being reflected in superior temporal gyrus. Though, the effects of lexicality suggests something more than pure transition probability is going on here.

Transition probability first negatively modulated neural responses, followed by positive modulation of neural responses, consistent with coordinated predictive and retrospective recognition processes, respectively. Furthermore, transition probability encoding was different for real English words compared with nonwords, providing evidence for online interactions with high-order linguistic knowledge.

Aging after noise exposure: Acceleration of cochlear synaptopathy in “recovered” ears→

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Noise exposure = bad.

The synaptopathic noise (100 dB) caused 35–50 dB threshold shifts at 24 h. By 2 weeks, thresholds had recovered, but synaptic counts and ABR amplitudes at high frequencies were reduced by up to ∼45%. As exposed animals aged, synaptopathy was exacerbated compared with controls and spread to lower frequencies. Proportional ganglion cell losses followed. Threshold shifts first appeared >1 year after exposure and, by ∼20 months, were up to 18 dB greater in the synaptopathic noise group. Outer hair cell losses were exacerbated in the same time frame (∼10% at 32 kHz).

Prospective motion correction of fMRI using optical tracking→

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The PMC system did not introduce extraneous artifacts for the no motion conditions and improved the time series temporal signal-to-noise by 30% to 40% for all combinations of low/high resolution and slow/fast head movement relative to the standard acquisition with no prospective correction. The numbers of activated voxels (p < 0.001, uncorrected) in both task-based experiments were comparable for the no motion cases and increased by 78% and 330%, respectively, for PMC on versus PMC off in the slow motion cases.

Bayesian segmentation of brainstem structures in MRI→

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Thanks to the generative nature of the scheme, the segmentation method is robust to changes in MRI contrast or acquisition hardware. Using cross validation, we show that the algorithm can segment the structures in previously unseen T1 and FLAIR scans with great accuracy (mean error under 1 mm) and robustness (no failures in 383 scans including 168 AD cases).

Miniaturized optical neuroimaging in unrestrained animals ($)→

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In this review, we highlight recent advances in the fabrication, characterization and application of miniaturized head-mounted optical neuroimaging systems pioneered by innovative investigators from a wide array of disciplines. We broadly classify these systems into those based on exogenous contrast agents, such as single- and two-photon microscopy systems; and those based on endogenous contrast mechanisms, such as multispectral or laser speckle contrast imaging systems. Finally, we conclude with a discussion of the strengths and weaknesses of these approaches along with a perspective on the future of this exciting new frontier in neuroimaging.

Comparing tract-based spatial statistics (TBSS) and manual labeling as diffusion analysis methods to detect white matter abnormalities→

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FA values from manual ROI and TBSS were strongly correlated (r = 0.94, P < 0.0001). Both methods found decreased FA in most ROIs for HIE infants. There was no significant interaction between method and group, indicating a similar ability to detect FA differences (F(1,19) = 0.599, P = 0.449). Sensitivity (manual: 0.709, TBSS: 0.694, 95% CI [–0.136, 0.163], P = 0.856), specificity (manual and TBSS: 0.716, 95% CI [–0.133, 0.133], P = 1), and standard error (manual: 0.009, TBSS: 0.007) were comparable.

Reproducibility of neuroimaging analyses across operating systems→

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With FSL, most Dice coefficients between subcortical classifications obtained on different operating systems remain above 0.9, but values as low as 0.59 are observed. Independent component analyses (ICA) of fMRI data differ between operating systems in one third of the tested subjects, due to differences in motion correction.

Ouch.

A first step to correct these reproducibility issues would be to use more precise representations of floating-point numbers in the critical sections of the pipelines. The numerical stability of pipelines should also be reviewed.

Orthogonalization of regressors in fMRI models→

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Very nice and important discussion of regressor orthogonalization.

The occurrence of collinearity in fMRI-based GLMs (general linear models) may reduce power or produce unreliable parameter estimates. It is commonly believed that orthogonalizing collinear regressors in the model will solve this problem, and some software packages apply automatic orthogonalization. However, the effects of orthogonalization on the interpretation of the resulting parameter estimates is widely unappreciated or misunderstood. Here we discuss the nature and causes of collinearity in fMRI models, with a focus on the appropriate uses of orthogonalization. Special attention is given to how the two popular fMRI data analysis software packages, SPM and FSL, handle orthogonalization, and pitfalls that may be encountered in their usage. Strategies are discussed for reducing collinearity in fMRI designs and addressing their effects when they occur.

And as a bonus, examples in an IPython notebook. Very cool.

Reminder: There's more to improving science than p values→

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Good reminder that there is a lot more to improving the quality of science than p values.

P values are an easy target: being widely used, they are widely abused. But, in practice, deregulating statistical significance opens the door to even more ways to game statistics — intentionally or unintentionally — to get a result. Replacing P values with Bayes factors or another statistic is ultimately about choosing a different trade-off of true positives and false positives. Arguing about the P value is like focusing on a single misspelling, rather than on the faulty logic of a sentence.

Resting state nuisance regressors remove variance with network structure→

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Really interesting work from Bright and Murphy. The "highlights":

  • Data variance removed by nuisance regressors contains network structure.
  • Simulated regressors unrelated to noise also extract data with network structure.
  • Random sampling of original data (as few as 10% of volumes) reveals robust networks.
  • After optimal number, motion regressors remove similar variance as simulated ones.
  • Excessive nuisance regressors extract random signal variance with network structure.

Early-late life trade-offs and the evolution of ageing in the wild→

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Here, we compiled 26 studies of free-ranging vertebrate populations that explicitly tested for a trade-off between performance in early and late life. Our review brings overall support for the presence of early-late life trade-offs, suggesting that the limitation of available resources leads individuals to trade somatic maintenance later in life for high allocation to reproduction early in life. We discuss our results in the light of two closely related theories of ageing—the disposable soma and the antagonistic pleiotropy theories—and propose that the principle of energy allocation roots the ageing process in the evolution of life-history strategies.

Friederici & Singer review: Grounding language processing on basic neurophysiological principles ($)→

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I haven't read this, but it looks interesting. Listed highlights:

  • Single neurons react similarly to persons and their names.
  • Nested oscillations can explain parallel processes.
  • Syntactic processes have a confined neural representation.
  • Different structural networks underlie different language aspects.

Modulation-frequency-specific adaptation in awake auditory cortex ($)→

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By recording responses to pairs of sinusoidally amplitude modulated (SAM) tones in the auditory cortex of awake squirrel monkeys, we show that the prior presentation of the SAM masker elicited persistent and tuned suppression of the firing rate to subsequent SAM signals. Population averages of these effects are compatible with adaptation in broadly tuned modulation channels.

Differential roles for attention subnetworks during reading→

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From the Schlaggar lab:

One set included bilateral Cingulo-opercular regions and mostly right-lateralized Dorsal Attention regions (CO/DA+). This CO/DA+ region set showed response properties consistent with a role in reporting which processing pathway (phonological or lexical) was biased for a particular trial. A second set was composed primarily of left-lateralized Frontal-parietal (FP) regions. Its signal properties were consistent with a role in response checking.

Divided attention disrupts perceptual encoding during speech recognition→

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Adding cognitive load increased the likelihood that listeners would select a word acoustically similar to the target even though its frequency was lower than that of the target. Thus, there was no evidence that cognitive load led to a high-frequency response bias. Rather, cognitive load seems to disrupt sublexical encoding, possibly by impairing perceptual acuity at the auditory periphery.