Neuroscience

Evaluation Summary:

This work seeks to resolve questions surrounding "unexplained variability in functional recovery" after experimental spinal cord injury in mice using virus-based retrograde tracing from cervical, thoracic and lumbar spinal cord injection sites, tissue clearing and cutting-edge imaging, to develop a supraspinal connectome or map of neurons in the brain that project to the spinal cord. They apply their methods to understand the differences in the connections between the brain and the cervical or lumbar spinal cord and to compare the connectome from intact mice to those of mice with mild, moderate and severe spinal cord injuries. This work will be of interest to neuroscientists interested in tissue clearing, viral labelling, and its applications to spinal cord injury.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

This paper will be of great interest to the field of developmental neuroscience and social communication. The authors identified prenatal sensorimotor vocal precursors by detecting rhythmic orofacial movements related to vocalizations. These findings will provide new insights into the development of vocal behavior in primates. The data acquired by a highly quantitative approach support the major claims of the paper.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #2 agreed to share their names with the authors.)

Evaluation Summary:

Eckstein and colleagues take a within-participant approach to answer two critical questions in the field of human reinforcement learning: to what extent do estimated computational model parameters generalize across different tasks and can their meaning be interpreted in the same way in different task contexts? The authors find that inferred parameters show moderate to little generalizability across tasks, and that their interpretation strongly depends on task context. Support for these claims could be further strengthened through additional simulations and by providing greater methodological detail.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

This manuscript will be of interest to cell and developmental biologists and neuroscientists. It addresses the question of how the number of connecting neurons in a circuit is matched whilst maintaining topography. It shows that non-autonomous control of neuronal number involves a relay mechanism through two distinct glial cell types, enabling the specification of distinct neuronal classes.

This manuscript was co-submitted with: https://www.biorxiv.org/content/10.1101/2022.02.21.481306v1

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 agreed to share their name with the authors.)

Evaluation Summary:

This is a useful study employing a well-established one-pawed reaching/grasping paradigm for fine-motor skill learning to assess if learning is associated with cortical structural changes as assessed by longitudinal MRI measurements in mice. The authors report a non-linear time course of MRI signal changes representing a decrease in grey matter and an increase in white matter volumes in the cerebral cortex and other regions. The authors ascribe these changes to increased myelination, a conclusion that is supported by quantitative immunolabelling for the myelin protein MBP. These results represent an interesting addition to the literature around myelination changes associated with learning/activity (adaptive myelination). Additional histological analysis of changes in myelination would bolster support for the authors' conclusions.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. The reviewers remained anonymous to the authors.)

Evaluation Summary:

This paper uses an impressively rich dataset (obtained and curated by the authors) to compare the structural brain connectomes of many animals spanning 6 taxonomic orders. The approach is innovative and relies on graph theoretical measures to describe the connectivity, which means it can be done without the need to spatially/functionally match the brains. The authors find that there is more variability between than within order. They attribute this effect to changes in local connectivity features, whereas global patterns are preserved. The approach can potentially be a useful way to study phylogeny and brain evolution.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 and Reviewer #3 agreed to share their name with the authors.)

Evaluation Summary:

This paper presents an exciting new automated package to investigate the hippocampal organization in new ways. As such, this package will be equally interesting for the fundamental basic and clinical neurosciences.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #2 agreed to share their name with the authors.)

Evaluation Summary:

This manuscript will be of interest to scientists working on learning and memory and synaptic plasticity. It provides a useful overview of different forms of plasticity taking place in the learning and memory center of the fly, the mushroom body. The study mostly uses an acetylcholine sensor to image activity, which is novel and helps to tie together previous studies reporting memory-induced changes in calcium transients. In particular, the study highlights the compartmentalised plasticity along Kenyon cell axon terminals, the main cell type of the mushroom body. The current version of the manuscript could be improved by including some key issues: (1) behavioral experiments for the Cac knock-down experiments, (2) specific controls for some of the imaging experiments, (3) consideration of the role of dopaminergic neurons and (4) acknowledgment of the complexity of the mushroom body circuit and the literature that has addressed this previously.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript.The reviewers remained anonymous to the authors.)

Evaluation Summary:

This study examined how mixture odors are represented in the mouse olfactory bulb. The authors found that compared to the responses in anesthetized mice, mixture responses are more linear in awake mice regardless whether the mice were engaged in a behavioral task or not. The results are potentially important as the results differ from previous studies which were done mostly in anesthetized animals, but the reviewers raised concerns for the validity and the strength of the conclusions.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #1 agreed to share their name with the authors.)

Evaluation Summary:

This manuscript will be of interest to readers in the field of anatomy and hippocampal physiology. The authors provide characterization of a novel projection pathway from layer 5a neurons in the MEC to CA1 of the hippocampus. They utilize cell specific viral labelling techniques, RNA-sequencing based projection mapping, and optogenetic aided in vitro physiology. The anatomical conclusions are well supported by the data. Future functional experiments will be necessary to establish the functional role of the projection.

(This preprint has been reviewed by eLife. We include the public reviews from the reviewers here; the authors also receive private feedback with suggested changes to the manuscript. Reviewer #3 agreed to share their name with the authors.)