Papers for the month of June 2018

Collins, E., Robinson, A.K., Behrmann, M.

"Distinct neural processes for the perception of familiar versus unfamiliar faces along the visual hierarchy revealed by EEG"
NeuroImage, 181:120-131

Mouse over here for a brief summary or click to open article in a new tab.Humans recognize faces with ease, despite the complexity of the task and of the visual system which underlies it. Different spatial regions, including both the core and extended face processing networks, and distinct temporal stages of processing have been implicated in face recognition, but there is ongoing controversy regarding the extent to which the mechanisms for recognizing a familiar face differ from those for an unfamiliar face. Here, we used electroencephalogram (EEG) and flicker SSVEP, a high signal-to-noise approach, and searchlight decoding methods to elucidate the mechanisms mediating the processing of familiar and unfamiliar faces in the time domain. Familiar and unfamiliar faces were presented periodically at 15 Hz, 6 Hz and 3.75 Hz either upright or inverted in separate blocks, with the rationale that faster frequencies require shorter processing times per image and tap into fundamentally different levels of visual processing. The 15 Hz trials, likely to reflect early visual processing, exhibited enhanced neural responses for familiar over unfamiliar face trials, but only when the faces were upright. In contrast, decoding methods revealed similar classification accuracies for upright and inverted faces for both familiar and unfamiliar faces. For the 6 Hz frequency, familiar faces had lower amplitude responses than unfamiliar faces, and decoding familiarity was more accurate for upright compared with inverted faces. Finally, the 3.75 Hz frequency revealed no main effects of familiarity, but decoding showed significant correlations with behavioral ratings of face familiarity, suggesting that activity evoked by this slow presentation frequency reflected higher-level, cognitive aspects of familiarity processing. This three-way dissociation between frequencies reveals that fundamentally different stages of the visual hierarchy are modulated by face familiarity. The combination of experimental and analytical approaches used here represent a novel method for elucidating spatio-temporal characteristics within the visual system.

"Multiphoton Intravital Calcium Imaging"
Current Protocols in Cytometry, e40:doi: 10.1002/cpcy.40

Mouse over here for a brief summary or click to open article in a new tab.This paper provides detailed protocols for in vivo 2-photon imaging in the mouse brain through either acute or chronically implanted cranial windows produced by either skull thinning or replacement with coverglass.

Ruff, D., Ni, A.

"Cognition as a Window into Neuronal Population Space"
Annual Review of Neuroscience, 41:77

Mouse over here for a brief summary or click to open article in a new tab.Understanding how cognitive processes affect the responses of sensory neurons may clarify the relationship between neuronal population activity and behavior. However, tools for analyzing neuronal activity have not kept up with technological advances in recording from large neuronal populations. Here, we describe prevalent hypotheses of how cognitive processes affect sensory neurons, driven largely by a model based on the activity of single neurons or pools of neurons as the units of computation.

Florian Cova, Brent Strickland, Angela Abatista, Aurélien Allard, James Andow, Mario Attie, James Beebe, Renatas Berniūnas, Jordane Boudesseul, Matteo Colombo, Fiery Cushman, Rodrigo Diaz, Noah N’Djaye, Nikolai van Dongen, Vilius Dranseika, Brian Earp, Antonio Gaitán Torres, Ivar Hannikainen, José V. Hernández-Conde, Wenjia Hu, François Jaquet, Kareem Khalifa, Hanna Kim, Markus Kneer, Joshua Knobe, Miklos Kurthy, Anthony Lantian, Shen-yi Liao, Tania Moerenhout, Christian Mott, Mark Phelan, Jonathan Phillips, Navin Rambharose, Kevin Reuter, Felipe Romero, Paulo Sousa, Jan Sprenger, Emile Thalabard, Kevin Tobia, Hugo Viciana, Daniel Wilkenfeld, Xiang Zhou

"Estimating the Reproducibility of Experimental Philosophy"
Review of Philosophy and Psychology, 1:1-36

Mouse over here for a brief summary or click to open article in a new tab.This paper assesses the replicability of experimental work in experimental philosophy, and reports a high rate of successful replications.

Wahlberg B, Ghuman H, Liu JR

"Ex vivo biomechanical characterization of syringe-needle ejections for intracerebral cell delivery."
Scientific Reports, 8:9194

Mouse over here for a brief summary or click to open article in a new tab.Intracerebral implantation of cell suspensions is finding its clinical translation with encouraging results in patients with stroke. However, the survival of cells in the brain remains poor. Although the biological potential of neural stem cells (NSCs) is widely documented, the biomechanical effects of delivering cells through a syringe-needle remain poorly understood. We here detailed the biomechanical forces (pressure, shear stress) that cells are exposed to during ejection through different sized needles (20G, 26G, 32G) and syringes (10, 50, 250 µL) at relevant flow rates (1, 5, 10 µL/min). A comparison of 3 vehicles, Phosphate Buffered Saline (PBS), Hypothermosol (HTS), and Pluronic, indicated that less viscous vehicles are favorable for suspension with a high cell volume fraction to minimize sedimentation. Higher suspension viscosity was associated with greater shear stress. Higher flow rates with viscous vehicle, such as HTS reduced viability by ~10% and also produced more apoptotic cells (28%). At 5 µL/min ejection using a 26G needle increased neuronal differentiation for PBS and HTS suspensions. These results reveal the biological impact of biomechanical forces in the cell delivery process. Appropriate engineering strategies can be considered to mitigate these effects to ensure the efficacious translation of this promising therapy.

Bostan, Andreea C.

"The basal ganglia and the cerebellum: nodes in an integrated network"
Nature Reviews Neuroscience, 19:338–350

Mouse over here for a brief summary or click to open article in a new tab.In this Review, Andreea Bostan and Peter Strick discuss findings indicating that the basal ganglia and the cerebellum are densely interconnected and, along with the cerebral cortex form an integrated network that operates over multiple functional domains.

de Kam D. Geurts A.C., Weerdesteyn W.

"Direction-Specific Instability Poststroke Is Associated With Deficient Motor Modules for Balance Control"
Neurorehabilitation and Neural Repair, 32:1

Mouse over here for a brief summary or click to open article in a new tab.Defective muscle coordination for balance recovery may contribute to stroke survivors’ propensity for falling. Thus, we investigated deficits in muscle coordination for postural control and their association to body sway following balance perturbations in people with stroke. Specifically, we compared the automatic postural responses of 8 leg and trunk muscles recorded bilaterally in unimpaired individuals and those with mild to moderate impairments after unilateral supratentorial lesions (>6 months). These responses were elicited by unexpected floor translations in 12 directions. We extracted motor modules (ie, muscle synergies) for each leg using nonnegative matrix factorization. We also determined the magnitude of perturbation-induced body sway using a single-link inverted pendulum model. Whereas the number of motor modules for balance was not affected by stroke, those formed by muscles with long latency responses were replaced by atypically structured paretic motor modules (atypical muscle groupings), which hints at direct cerebral involvement in long-latency feedback responses. Other paretic motor modules had intact structure but were poorly recruited, which is indicative of indirect cerebral control of balance. Importantly, these paretic deficits were strongly associated with postural instability in the preferred activation direction of the impaired motor modules. Finally, these deficiencies were heterogeneously distributed across stroke survivors with lesions in distinct locations, suggesting that different cerebral substrates may contribute to balance control. In conclusion, muscle coordination deficits in the paretic limb of stroke survivors result in direction-specific postural instability, which highlights the importance of targeted interventions to address patient-specific balance impairments.

Du X, Rowland LM, Summerfelt A, Choa FS, Wisner K, Wijtenburg A, Chiappelli J, Kochunov P, Hong LE

"Cerebellar-Stimulation Evoked Prefrontal Electrical Synchrony Is Modulated by GABA."
Cerebellum, 0:1-14

Mouse over here for a brief summary or click to open article in a new tab.Stronger prefrontal synchrony evoked by TMS over the cerebelum was associated with better working memory but surprisingly worse motor coordination, which suggests competing effects for motor activity and cognition.


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