The Adult Murine Intestine is Dependent on Constitutive Laminin-γ1 Synthesis.

Laminin-γ1 is required for early embryonic development; however, the need for laminin-γ1 synthesis in adulthood is unknown. A global and inducible mouse model of laminin-γ1 deficiency was generated to address this question. Genetic ablation of the Lamc1 gene in adult mice was rapidly lethal.

Dynamin 2 is required for GPVI signaling and platelet hemostatic function in mice.

Receptor-mediated endocytosis, which contributes to a wide range of cellular functions, including receptor signaling, cell adhesion, and migration, requires endocytic vesicle release by the large GTPase dynamin 2. Here, the role of dynamin 2 was investigated in platelet hemostatic function using both pharmacological and genetic approaches. Pf4-Cre ( ) mice specifically lacking dynamin 2 within the platelet lineage developed severe thrombocytopenia and bleeding diathesis and platelets adhered poorly to collagen under arterial shear rates.

Impact of cannabis use on prefrontal and parietal cortex gyrification and surface area in adolescents and emerging adults.

Background: Regions undergoing maturation with CB1 receptors may be at increased risk for cannabis-induced alterations. Here, we examine the relationships between cannabis use and prefrontal (PFC) and inferior parietal gyrification and surface area (SA) in youth.

Methods: Participants included 33 cannabis users and 35 controls (ages 18-25).

Poorer frontolimbic white matter integrity is associated with chronic cannabis use, FAAH genotype, and increased depressive and apathy symptoms in adolescents and young adults.

Background: The heaviest period of cannabis use coincides with ongoing white matter (WM) maturation. Further, cannabis-related changes may be moderated by FAAH genotype (rs324420). We examined the association between cannabis use and FAAH genotype on frontolimbic WM integrity in adolescents and emerging adults.

Effects of marijuana use on prefrontal and parietal volumes and cognition in emerging adults.

Rationale: Chronic marijuana (MJ) use among adolescents has been associated with structural and functional abnormalities, particularly in developing regions responsible for higher order cognition.

Objectives: This study investigated prefrontal (PFC) and parietal volumes and executive function in emerging adult MJ users and explored potential gender differences.

Methods: Participants (ages 18-25) were 27 MJ users and 32 controls without neurologic or psychiatric disorders or heavy other drug use.

Learning redundant motor tasks with and without overlapping dimensions: facilitation and interference effects.

Prior learning of a motor skill creates motor memories that can facilitate or interfere with learning of new, but related, motor skills. One hypothesis of motor learning posits that for a sensorimotor task with redundant degrees of freedom, the nervous system learns the geometric structure of the task and improves performance by selectively operating within that task space. We tested this hypothesis by examining if transfer of learning between two tasks depends on shared dimensionality between their respective task spaces.

The effect of movement rate and complexity on functional magnetic resonance signal change during pedaling.

We used functional magnetic resonance imaging (fMRI) to record human brain activity during slow (30 RPM), fast (60 RPM), passive (30 RPM), and variable rate pedaling. Ten healthy adults participated. After identifying regions of interest, the intensity and volume of brain activation in each region was calculated and compared across conditions (p < .

Pedaling alters the excitability and modulation of vastus medialis H-reflexes after stroke.

Objective: Individuals post-stroke display abnormal Group Ia reflex excitability. Pedaling has been shown to reduce Group Ia reflexes and to normalize the relationship between EMG and reflex amplitude in the paretic soleus (SO). The purpose of this study was to determine whether these changes extend to the paretic quadriceps.

A novel technique for examining human brain activity associated with pedaling using fMRI.

Advances in neural imaging technologies, such as functional magnetic resonance imaging (fMRI), have made it possible to obtain images of human brain activity during motor tasks. However, technical challenges have made it difficult to image the brain during multijoint lower limb movements like those involved in locomotion. We developed an MR compatible pedaling device and recorded human brain activity associated with rhythmic, alternating flexion and extension of the lower extremities.

Soleus H-reflex excitability during pedaling post-stroke.

A major contributor to impaired locomotion post-stroke is abnormal phasing of paretic muscle activity, but the mechanisms remain unclear. Previous studies have shown that, in the paretic limb of people post-stroke, Group Ia reflexes are abnormally elevated and fail to decrease in amplitude during locomotion. Hence, we hypothesized that inappropriate muscle phasing may be associated with enhanced transmission in the monosynaptic Group Ia afferent pathway.