Plasticity in D1-Like Receptor Expression Is Associated with Different Components of Cognitive Processes

Dopamine D1-like receptors consist of D1 (D1A) and D5 (D1B) receptors and play a key role in working memory. However, their possibly differential contribution to working memory is unclear. We combined a working memory training protocol with a stepwise increase of cognitive subcomponents and real-time RT-PCR analysis of dopamine receptor expression in pigeons to identify molecular changes that accompany training of isolated cognitive subfunctions. In birds, the D1-like receptor family is extended and consists of the D1A, D1B, and D1D receptors. Our data show that D1B receptor plasticity follows a training that includes active mental maintenance of information, whereas D1A and D1D receptor plasticity in addition accompanies learning of stimulus-response associations. Plasticity of D1-like receptors plays no role for processes like response selection and stimulus discrimination. None of the tasks altered D2 receptor expression. Our study shows that different cognitive components of working memory training have distinguishable effects on D1-like receptor expression

Song Practice Promotes Acute Vocal Variability at a Key Stage of Sensorimotor Learning

BACKGROUND: Trial by trial variability during motor learning is a feature encoded by the basal ganglia of both humans and songbirds, and is important for reinforcement of optimal motor patterns, including those that produce speech and birdsong. Given the many parallels between these behaviors, songbirds provide a useful model to investigate neural mechanisms underlying vocal learning. In juvenile and adult male zebra finches, endogenous levels of FoxP2, a molecule critical for language, decrease two hours after morning song onset within area X, part of the basal ganglia-forebrain pathway dedicated to song. In juveniles, experimental 'knockdown' of area X FoxP2 results in abnormally variable song in adulthood. These findings motivated our hypothesis that low FoxP2 levels increase vocal variability, enabling vocal motor exploration in normal birds. METHODOLOGY/PRINCIPAL FINDINGS: After two hours in either singing or non-singing conditions (previously shown to produce differential area X FoxP2 levels), phonological and sequential features of the subsequent songs were compared across conditions in the same bird. In line with our prediction, analysis of songs sung by 75 day (75d) birds revealed that syllable structure was more variable and sequence stereotypy was reduced following two hours of continuous practice compared to these features following two hours of non-singing. Similar trends in song were observed in these birds at 65d, despite higher overall within-condition variability at this age. CONCLUSIONS/SIGNIFICANCE: Together with previous work, these findings point to the importance of behaviorally-driven acute periods during song learning that allow for both refinement and reinforcement of motor patterns. Future work is aimed at testing the observation that not only does vocal practice influence expression of molecular networks, but that these networks then influence subsequent variability in these skills

Positive impact of dynamic seeding of mesenchymal stem cells on bone-like biodegradable scaffolds with increased content of calcium phosphate nanoparticles

One of the main aims of bone tissue engineering, regenerative medicine and cell therapy is development of an optimal artificial environment (scaffold) that can trigger a favorable response within the host tissue, it is well colonized by resident cells of organism and ideally, it can be in vitro pre-colonized by cells of interest to intensify the process of tissue regeneration. The aim of this study was to develop an effective tool for regenerative medicine, which combines the optimal bone-like scaffold and colonization technique suitable for cell application. Accordingly, this study includes material (physical, chemical and structural) and in vitro biological evaluation of scaffolds prior to in vivo study. Thus, porosity, permeability or elasticity of two types of bone-like scaffolds differing in the ratio of collagen type I and natural calcium phosphate nanoparticles (bCaP) were determined, then analyzes of scaffold interaction with mesenchymal stem cells (MSCs) were performed. Simultaneously, dynamic seeding using a perfusion bioreactor followed by static cultivation was compared with standard static cultivation for the whole period of cultivation. In summary, cell colonization ability was estimated by determination of cell distribution within the scaffold (number, depth and homogeneity), matrix metalloproteinase activity and gene expression analysis of signaling molecules and differentiation markers. Results showed, the used dynamic colonization technique together with the newly-developed collagen-based scaffold with high content of bCaP to be an effective combined tool for producing bone grafts for bone implantology and regenerative medicine

Avian brains and a new understanding of vertebrate brain evolution.

We believe that names have a powerful influence on the experiments we do and the way in which we think. For this reason, and in the light of new evidence about the function and evolution of the vertebrate brain, an international consortium of neuroscientists has reconsidered the traditional, 100-year-old terminology that is used to describe the avian cerebrum. Our current understanding of the avian brain - in particular the neocortex-like cognitive functions of the avian pallium - requires a new terminology that better reflects these functions and the homologies between avian and mammalian brains