Neuroscience

eLife Assessment

This valuable study characterises the activity of motor units from two of the three anatomical subdivisions ("heads") of the triceps muscle while mice walked on a treadmill at various speeds. Altogether, this is the most thorough characterisation of motor unit activity in walking mice to date, providing solid evidence for probabilistic recruitment of motor units that differed between the two heads.

eLife Assessment

This valuable study links psychological theories of chunking with a physiological implementation based on short-term synaptic plasticity and synaptic augmentation. The theoretical derivation for increased memory capacity via hierarchical chunking is solid. However, the model robustness and biological grounding of the mechanism - including many aspects that were hard-wired, chunking cues, and parameter ranges - as well as its evaluation in the task settings that motivated the study, are incomplete. Additional simulations to test robustness in more cognitively and biologically realistic settings, a systematic parameter analysis, and stronger links to prior work would substantially strengthen the manuscript and increase its impact across disciplines.

eLife Assessment

This is a potentially important paper attempting to identify neutral correlates of memory engram expression in humans, and how they change during forgetting. The questions posed are clear and novel. The methods employed, namely behavioral analysis, high-resolution functional magnetic resonance imaging, and representational similarity analysis, are advanced, integrative, and appropriate. The experiments are well designed and combine analysis of recollection and familiarity of object/face associations. However, substantial questions remain as to the validity of the incomplete statistical analyses applied to the imaging data, as well as the parsing of and interpretation of the behavioral data.

eLife Assessment

The granularity with which neural activity in the sensorimotor cortex of mice corresponds to voluntary forelimb motion is a key open question. This paper provides compelling evidence for the encoding of low-level features like joint angles and represents an important step forward toward understanding cortical limb control signals.

eLife Assessment

This important study uses an original method to address the longstanding question of why reaching movements are often biased. The combination of a wide range of experimental conditions and computational modeling is a strength. Convincing evidence is presented in support of the main claim that most of the biases in 2-D movement planning originate in misalignment between visuo-proprioceptive reference frames.

eLife Assessment

This valuable study assesses through simulations how several features of local cortical circuits - interneuron subtypes, their specific targeting of dendritic compartments, and certain brain rhythms - together affect the integration of synaptic inputs by a pyramidal cell. Employing several carefully considered simulation setups they convincingly demonstrate that beta rhythms are best suited to modulate and control dendritic Ca-spikes while gamma rhythms affect their coupling to somatic spiking, or how basal inputs are directly integrated into somatic spikes. However, the baseline setup may be idealized for the generation of the events in question and it would be beneficial if the similarity to the in-vivo activity regime was demonstrated further. The results will be relevant for neuroscientists studying local circuits or developing more abstract theories at the systems level.

eLife Assessment

In this valuable study, Parrotta et al. showed that it is possible to modulate pain perception and heart rate by providing false heart rate (HR) acoustic feedback before administering electrical cutaneous shocks. The evidence supporting the claims of the authors is rather solid, although what they consider an interoceptive signal is not necessarily supported as such by the results. In this regard, including a larger number of trials per participant, increasing the sample size, and adding a measure of actual pain perception after its induction would have strengthened the study. Although mechanisms and some alternative explanations for this effect remain to be addressed, the work will nonetheless be of interest to neuroscientists working on predictions and perception, health psychologists, pain researchers, and placebo researchers.

eLife Assessment

Using their unique Fish-On-Chips optofluidics platform, the authors make three important findings: the presence of precise coupling between saccades and tail flips can be used to discriminate between turning or gliding behaviours; aversive and appetitive chemosensory cues differentially modulate these behaviours; transformation from cue valence to behaviour is encoded by the pallium. The evidence supporting these findings is solid. The work advances our understanding of the ancient interplay between chemosensation and motor output through the modulation of eye-body coordination.

eLife Assessment

This important study examined age-related changes in cerebellar function by testing a large sample of younger and older adults, including 30 over 80 years old, on motor and cognitive tasks linked to the cerebellum and conducting structural imaging. Their findings show that cerebellar-dependent functions are mostly maintained or even enhanced across the lifespan, with cerebellar-mediated motor abilities remaining intact despite degeneration, in contrast to non-cerebellar measures. Overall, the authors provide solid evidence in support of preserved cerebellar function with age. These results highlight the resilience and redundancy of cerebellar circuits and offer key insights into aging and motor behavior.

eLife Assessment

This important study employs functional magnetic resonance spectroscopy (fMRS) to demonstrate that GABAergic inhibition in the parietal cortex actively suppresses goal-irrelevant distractors, thereby facilitating goal-directed visual tracking. The data and analyses are solid, and the methodology is validated. However, the link between the metabolic changes and the purported functional mechanisms is incomplete due to concerns with experimental design and interpretations. The study will be of interest to researchers studying goal-directed behavior and neurochemical dynamics in cognitive processing.