Papers for the month of November 2015

"Using mice to model Obsessive Compulsive Disorder: From genes to circuits"
Neuroscience, 15:1-17

Mouse over here for a brief summary or click to open article in a new tab.This paper describes recent advances in the use of new technologic approaches that permit precise manipulation of genes and circuits to dissect pathologic changes underlying OCD.

Murphy M., Nau AC., Fisher C., Kim SG.,

"Top-down influence on the visual cortex of the blind during sensory substitution"
NeuroImage, 125:932-940

Mouse over here for a brief summary or click to open article in a new tab.We used a sensory substitution task to investigate plasticity due to blindness. We report increased top-down influence in visual cortex activity of the blind. Top-down modulation is greater in congenitally blind compared to acquired blind. Blindness increases connectivity between visual and task-positive networks.

"Why the "stimulus-error" did not go away"
Studies in History and Philosophy of Science, Volume 56, April 2016:33-42

Mouse over here for a brief summary or click to open article in a new tab.An article on the history of methods in early introspectionist psychology, with comparison to more recent research on perceptual constancies.

Poplawsky A., Fukuda M., Murphy M., Kim S.-G.

"Layer-Specific fMRI Responses to Excitatory and Inhibitory Neuronal Activities in the Olfactory Bulb"
The Journal of Neuroscience, 35:15263-15275

Mouse over here for a brief summary or click to open article in a new tab.Functional magnetic resonance imaging (fMRI) measures neuronal activity indirectly by way of the vascular response, but it is unclear if it accurately measures neuronal activity within single cortical layers at high resolutions. To investigate this, we activated discrete layers of the rat olfactory bulb and observed that the greatest cerebral blood volume-weighted fMRI responses were separated to the same layers as the evoked neuronal activities, whereas the blood oxygenation level-dependent (BOLD) fMRI responses were poorly localized with some exception to the poststimulus undershoot.

Hitchens KT, Liu JR, Richardson RM

"Detection of aberrant hippocampal mossy fiber connections: Ex vivo mesoscale diffusion MRI and microtractography with histological validation in a patient with uncontrolled temporal lobe epilepsy."
Human Brain Mapping, NA:NA

Mouse over here for a brief summary or click to open article in a new tab.Understanding the neurobiology and functional connectivity of hippocampal structures is essential for improving the treatment of mesial temporal lobe epilepsy. At the macroscale, in vivo MRI often reveals hippocampal atrophy and decreased fractional anisotropy, whereas at the microscopic scale, there frequently is evidence of neuronal loss and gliosis. Mossy fiber sprouting in the dentate gyrus (DG), with evidence of glutamatergic synapses in the stratum moleculare (SM) putatively originating from granule cell neurons, may also be observed. This aberrant connection between the DG and SM could produce a reverberant excitatory circuit. However, this hypothesis cannot easily be evaluated using macroscopic or microscopic techniques. We here demonstrate that the ex vivo mesoscopic MRI of surgically excised hippocampi can bridge the explanatory and analytical gap between the macro- and microscopic scale. Specifically, diffusion- and T2-weighted MRI can be integrated to visualize a cytoarchitecture that is akin to immunohistochemistry. An appropriate spatial resolution to discern individual cell layers can then be established. Processing of diffusion tensor images using tractography detects extra- and intrahippocampal connections, hence providing a unique systems view of the hippocampus and its connected regions. Here, this approach suggests that there is indeed an aberrant connection between the DG and SM, supporting the sprouting hypothesis of a reverberant excitatory network. Mesoscopic ex vivo MR imaging hence provides an exciting new avenue to study hippocampi from treatment-resistant patients and allows exploration of existing hypotheses, as well as the development of new treatment strategies based on these novel insights.

Ramachandran, Suchitra, Meyer, Travis

"Prediction Suppression in Monkey Inferotemporal Cortex Depends on the Conditional Probability between Images"
Journal of Neurophysiology, [Epub ahead of print]:*

Mouse over here for a brief summary or click to open article in a new tab.When monkeys view two images in fixed sequence repeatedly over the course of days and weeks, neurons in inferotemporal cortex develop prediction suppression. The trailing image elicits only a weak response when presented following the leading image that preceded it during training. We show that this effect depends not simply on repeated pairing between the images (contiguity) but on their conditional probability relative to each other (contingency).

Divito C.B., Steece-Collier K., Case D.T., Williams S.P., Stancati J.A., Zhi L., Rubio M.E., Sortwell C.E., Collier T.J., Sulzer D., Edwards R., H. Zhang H., Seal R.P.

"Loss of VGLUT3 Produces Circadian-Dependent Hyperdopaminergia and Ameliorates Motor Dysfunction and l-Dopa-Mediated Dyskinesias in a Model of Parkinson's Disease."
Journal of Neuroscience, 35:14983-14999

Mouse over here for a brief summary or click to open article in a new tab.In this article, loss of VGLUT3 ameliorates motor deficits in a model of Parkinson's disease. Loss of the transporter also creates a circadian-dependent increase in DA synthesis, packaging, and release.

Griffin DM., Hoffman DS

"Corticomotoneuronal cells are "functionally tuned""
Science, 350:667 - 670

Mouse over here for a brief summary or click to open article in a new tab.Individual corticomotoneuronal cells contribute to a single function of its target muscles.

Jack Grinband & Vincent Ferrera

"The importance of decision onset"
Journal of Neurophysiology, in press:0

Mouse over here for a brief summary or click to open article in a new tab.Everything you always wanted to know (but were afraid to ask) about when, how and why to start the process of integrating evidence for simple perceptual decisions.


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