Papers for the month of July 2019

Matteo Scopelliti

"Ultrasonically sculpted virtual relay lens for in situ microimaging"
Nature Light Science and Applications, 8:65

Mouse over here for a brief summary or click to open article in a new tab.We show that a virtual optical graded-index (GRIN) lens can be sculpted in the medium using in situ reconfigurable ultrasonic interference patterns to relay images through the medium. Ultrasonic wave patterns change the local density of the medium to sculpt a graded refractive index pattern normal to the direction of light propagation, which modulates the phase front of light, causing it to focus within the medium and effectively creating a virtual relay lens. We demonstrate the in situ relay imaging and resolving of small features (22 µm) through a turbid medium (optical thickness = 5.7 times the scattering mean free path), which is normally opaque. The focal distance and the numerical aperture of the sculpted optical GRIN lens can be tuned by changing the ultrasonic wave parameters. As an example, we experimentally demonstrate that the axial focal distance can be continuously scanned over a depth of 5.4 mm in the modulated medium and that the numerical aperture can be tuned up to 21.5%. The interaction of ultrasonic waves and light can be mediated through different physical media, including turbid media, such as biological tissue, in which the ultrasonically sculpted GRIN lens can be used for relaying images of the underlying structures through the turbid medium, thus providing a potential alternative to implanting invasive endoscopes.

Popov, V., Zhang, Q., Koch, G.E., Calloway, R.C.

"Semantic knowledge influences whether novel episodic associations are represented symmetrically or asymmetrically."
Memory & Cognition, 0:1-15

Mouse over here for a brief summary or click to open article in a new tab.The authors provide new evidence concerning two opposing views of episodic associations: The independent-association hypothesis posits that associations are unidirectional and separately modifiable links (A→B and A←B); in contrast, the associative-symmetry hypothesis proposes that a single, bidirectional association exists between A and B (A↔B). The authors concluded that episodic associations can have either a single bidirectional representation or separate directional representations, depending on the semantic relatedness of their constituent items.

Massot C., Jagadisan U.

"Sensorimotor transformation elicits systematic patterns of activity along the dorsoventral extent of the superior colliculus in the macaque monkey"
Communications Biology, 2:287

Mouse over here for a brief summary or click to open article in a new tab.Study examines sensorimotor transformation along the dorsoventral axis of the monkey superior colliculus with laminar probes

Hirad, A., Bazarian, J., Merchant-Borna, K., Garcea, F, Heilbronner, S, Paul, D, Hintz, E, van Wijngaarden, E, Schifitto, G, Wright, D, Espinoza, T, Mahon, B

"A common neural signature of brain injury in concussion and subconcussion"
Science Advances, 5:eaau3460

Mouse over here for a brief summary or click to open article in a new tab.The midbrain is biomechanically susceptible to force loading from repetitive subconcussive head impacts (RSHI), is a site of tauopathy in chronic traumatic encephalopathy (CTE), and regulates functions (e.g., eye movements) often disrupted in concussion. In a prospective longitudinal design, we demonstrate there are reductions in midbrain white matter integrity due to a single season of collegiate football, and that the amount of reduction in midbrain white matter integrity is related to the amount of rotational acceleration to which players’ brains are exposed.

Schneider CL, Majewska AK, Busza A, Williams ZR, Sahin B

"Selective serotonin reuptake inhibitors for functional recovery after stroke: similarities with the critical period and the role of experience-dependent plasticity"
Journal of Neurology, not yet assigned:1-7

Mouse over here for a brief summary or click to open article in a new tab.There has been a growing interest in the potential for plasticity-inducing pharmacological interventions to enhance post-stroke recovery. Here we propose a model for the mechanism by which selective serotonin reuptake inhibitors may enhance plasticity after ischemic brain injury.

Fukuda, M., Kim, SG

"Foundations of layer-specific fMRI and investigations of neurophysiological activity in the laminarized neocortex and olfactory bulb of animal models"
NeuroImage, 199:718-729

Mouse over here for a brief summary or click to open article in a new tab.In this review, we will examine different fMRI contrasts and their appropriate uses for layer-specific fMRI, and how localized laminar processing was examined in the neocortex and olfactory bulb.

Popov, V., Marevic, I., Rummel, Jan.

"Forgetting Is a Feature, Not a Bug: Intentionally Forgetting Some Things Helps Us Remember Others by Freeing Up Working Memory Resources"
Psychological Science, Advance Online Publication:1-15

Mouse over here for a brief summary or click to open article in a new tab.We found that when participants are instructed to remember some items on a study list, but to forget others, their memory for an item is better when the preceding study items had to be forgotten. This effect increased when more of the preceding study items had to be forgotten. We propose that storing information in memory depletes a limited capacity resource which recovers gradually over time and that when one item depletes more resources there are fewer resources to store subsequently studied items.

Williams, J., Watson, A., Vazquez, A.

"Viral-Mediated Optogenetic Stimulation of Peripheral Motor Nerves in Non-human Primates"
Frontiers in Neuroscience, 13:759

Mouse over here for a brief summary or click to open article in a new tab.Gene therapy to insert light sensitive opsins into peripheral motor nerves via viral vectors, thus allowing optogenetic stimulation of muscle activity to reanimate paralyzed limbs, has been limited to rodent models to date. In this study, we demonstrate the feasibility of transducing macaque peripheral nerves with ChR2 using an AAV6 vector and stimulating muscle activity using blue pulses of light to the nerve. In addition, we highlight several potential roadblocks of this flavor of gene therapy that must be addressed prior to viable clinical translation including variable temporal and spatial profiles of gene expression.

Martin, K. I.

"Prior preparation and motivational characteristics mediate relations between gender and learning outcomes in introductory physics."
Bilingualism: Language & Cognition, 0:0

Mouse over here for a brief summary or click to open article in a new tab.Typically concrete words are learned better than abstract words (Kaushanskaya & Rechtzigel, 2012), and nouns are learned better than verbs (Kauschke & Stenneken, 2008). However, most studies on concreteness have not manipulated grammatical class (and vice versa), leaving the relationship between the two unclear. Hierarchical regression analyses provided evidence that the grammatical class effect is separable from the concreteness effect. This result challenges a strict concreteness-based source of noun/verb differences. The results also suggest that the influences of concreteness and grammatical class may vary across language measures and tasks.


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