Representation of motor habit in a sequence of repetitive reach and grasp movements performed by macaque monkeys: evidence for a contribution of the dorsolateral prefrontal cortex.

In the context of an autologous cell transplantation study, a unilateral biopsy of cortical tissue was surgically performed from the right dorsolateral prefrontal cortex (dlPFC) in two intact adult macaque monkeys (dlPFC lesioned group), together with the implantation of a chronic chamber providing access to the left motor cortex. Three other monkeys were subjected to the same chronic chamber implantation, but without dlPFC biopsy (control group). All monkeys were initially trained to perform sequential manual dexterity tasks, requiring precision grip. The motor performance and the prehension's sequence (temporal order to grasp pellets from different spatial locations) were analysed for each hand. Following the surgery, transient and moderate deficits of manual dexterity per se occurred in both groups, indicating that they were not due to the dlPFC lesion (most likely related to the recording chamber implantation and/or general anaesthesia/medication). In contrast, changes of motor habit were observed for the sequential order of grasping in the two monkeys with dlPFC lesion only. The changes were more prominent in the monkey subjected to the largest lesion, supporting the notion of a specific effect of the dlPFC lesion on the motor habit of the monkeys. These observations are reminiscent of previous studies using conditional tasks with delay that have proposed a specialization of the dlPFC for visuo-spatial working memory, except that this is in a different context of "free-will", non-conditional manual dexterity task, without a component of working memory.

Subcellular fractionation of stored red blood cells reveals a compartment-based protein carbonylation evolution.

During blood banking, erythrocytes undergo storage lesions, altering or degrading their metabolism, rheological properties, and protein content. Carbonylation is a hallmark of protein oxidative lesions, thus of red blood cell oxidative stress. In order to improve global erythrocyte protein carbonylation assessment, subcellular fractionation has been established, allowing us to work on four different protein populations, namely soluble hemoglobin, hemoglobin-depleted soluble fraction, integral membrane and cytoskeleton membrane protein fractions. Carbonylation in erythrocyte-derived microparticles has also been investigated. Carbonylated proteins were derivatized with 2,4-dinitrophenylhydrazine (2,4-DNPH) and quantified by western blot analyses. In particular, carbonylation in the cytoskeletal membrane fraction increased remarkably between day 29 and day 43 (P<0.01). Moreover, protein carbonylation within microparticles released during storage showed a two-fold increase along the storage period (P<0.01). As a result, carbonylation of cytoplasmic and membrane protein fractions differs along storage, and the present study allows explaining two distinct steps in global erythrocyte protein carbonylation evolution during blood banking. This article is part of a Special Issue entitled: Integrated omics.

Multisensory facilitation of behavior in monkeys: effects of stimulus intensity.

Multisensory stimuli can improve performance, facilitating RTs on sensorimotor tasks. This benefit is referred to as the redundant signals effect (RSE) and can exceed predictions on the basis of probability summation, indicative of integrative processes. Although an RSE exceeding probability summation has been repeatedly observed in humans and nonprimate animals, there are scant and inconsistent data from nonhuman primates performing similar protocols. Rather, existing paradigms have instead focused on saccadic eye movements. Moreover, the extant results in monkeys leave unresolved how stimulus synchronicity and intensity impact performance. Two trained monkeys performed a simple detection task involving arm movements to auditory, visual, or synchronous auditory-visual multisensory pairs. RSEs in excess of predictions on the basis of probability summation were observed and thus forcibly follow from neural response interactions. Parametric variation of auditory stimulus intensity revealed that in both animals, RT facilitation was limited to situations where the auditory stimulus intensity was below or up to 20 dB above perceptual threshold, despite the visual stimulus always being suprathreshold. No RT facilitation or even behavioral costs were obtained with auditory intensities 30-40 dB above threshold. The present study demonstrates the feasibility and the suitability of behaving monkeys for investigating links between psychophysical and neurophysiologic instantiations of multisensory interactions.

Red blood cell-derived microparticles isolated from blood units initiate and propagate thrombin generation.

BACKGROUND: Red blood cell-derived microparticles (RMPs) are small phospholipid vesicles shed from RBCs in blood units, where they accumulate during storage. Because microparticles are bioactive, it could be suggested that RMPs are mediators of posttransfusion complications or, on the contrary, constitute a potential hemostatic agent. STUDY DESIGN AND METHODS: This study was performed to establish the impact on coagulation of RMPs isolated from blood units. Using calibrated automated thrombography, we investigated whether RMPs affect thrombin generation (TG) in plasma. RESULTS: We found that RMPs were not only able to increase TG in plasma in the presence of a low exogenous tissue factor (TF) concentration, but also to initiate TG in plasma in absence of exogenous TF. TG induced by RMPs in the absence of exogenous TF was neither affected by the presence of blocking anti-TF nor by the absence of Factor (F)VII. It was significantly reduced in plasma deficient in FVIII or F IX and abolished in FII-, FV-, FX-, or FXI-deficient plasma. TG was also totally abolished when anti-XI 01A6 was added in the sample. Finally, neither Western blotting, flow cytometry, nor immunogold labeling allowed the detection of traces of TF antigen. In addition, RMPs did not comprise polyphosphate, an important modulator of coagulation. CONCLUSIONS: Taken together, our data show that RMPs have FXI-dependent procoagulant properties and are able to initiate and propagate TG. The anionic surface of RMPs might be the site of FXI-mediated TG amplification and intrinsic tenase and prothrombinase complex assembly.