A Minimally-Invasive Procedure for Sexing Young Zebra Finches

Zebra finches have been widely used to study neurobiology underlying vocal development. Because only male zebra finches learn song, efficient developmental use of these animals requires early determination of sex at ages that precede maturation of secondary sex characteristics. We have developed a sex determination method that combines a forensics method of genomic DNA isolation (from very small blood samples) with PCR amplification from Z and W sex chromosomes (males are ZZ, females ZW). This combination results in a minimally-invasive yet highly reliable and convenient genotyping method. Originally published Journal of Neuroscience Methods, Vol. 164, No. 1, Aug 200

Cannabinoid exposure during zebra finch sensorimotor vocal learning persistently alters expression of endocannabinoid signaling elements and acute agonist responsiveness

<p>Abstract</p> <p>Background</p> <p>Previously we have found that cannabinoid treatment of zebra finches during sensorimotor stages of vocal development alters song patterns produced in adulthood. Such persistently altered behavior must be attributable to changes in physiological substrates responsible for song. We are currently working to identify the nature of such physiological changes, and to understand how they contribute to altered vocal learning. One possibility is that developmental agonist exposure results in altered expression of elements of endocannabinoid signaling systems. To test this hypothesis we have studied effects of the potent cannabinoid receptor agonist WIN55212-2 (WIN) on endocannabinoid levels and densities of CB₁immunostaining in zebra finch brain.</p> <p>Results</p> <p>We found that late postnatal WIN treatment caused a long-term global disregulation of both levels of the endocannabinoid, 2-arachidonyl glycerol (2-AG) and densities of CB₁immunostaining across brain regions, while repeated cannabinoid treatment in adults produced few long-term changes in the endogenous cannabinoid system.</p> <p>Conclusions</p> <p>Our findings indicate that the zebra finch endocannabinoid system is particularly sensitive to exogenous agonist exposure during the critical period of song learning and provide insight into susceptible brain areas.</p

Wave curves: Simulating Lagrangian water waves on dynamically deforming surfaces

We propose a method to enhance the visual detail of a water surface simulation. Our method works as a post-processing step which takes a simulation as input and increases its apparent resolution by simulating many detailed Lagrangian water waves on top of it. We extend linear water wave theory to work in non-planar domains which deform over time, and we discretize the theory using Lagrangian wave packets attached to spline curves. The method is numerically stable and trivially parallelizable, and it produces high frequency ripples with dispersive wave-like behaviors customized to the underlying fluid simulation

CB1 Cannabinoid Receptor Activation Dose-Dependently Modulates Neuronal Activity within Caudal but not Rostral Song Control Regions of Adult Zebra Finch Telencephalon

CB1 cannabinoid receptors are distinctly expressed at high density within several regions of zebra finch telencephalon including those known to be involved in song learning (lMAN and Area X) and production (HVC and RA). Because: (1) exposure to cannabinoid agonists during developmental periods of auditory and sensory-motor song learning alters song patterns produced later in adulthood and; (2) densities of song region expression of CB1 waxes-and-wanes during song learning, it is becoming clear that CB1 receptor-mediated signaling is important to normal processes of vocal development. To better understand mechanisms involved in cannabinoid modulation of vocal behavior we have investigated the dose-response relationship between systemic cannabinoid exposure and changes in neuronal activity (as indicated by expression of the transcription factor, c- Fos) within telencephalic brain regions with established involvement in song learning and/or control. In adults we have found that low doses (0.1 mg/kg) of the cannabinoid agonist WIN-55212-2 decrease neuronal activity (as indicated by densities of c-fos-expressing nuclei) within vocal motor regions of caudal telencephalon (HVC and RA) while higher doses (3 mg/kg) stimulate activity. Both effects were reversed by pretreatment with the CB1-selective antagonist rimonabant. Interestingly, no effects of cannabinoid treatment were observed within the rostral song regions lMAN and Area X, despite distinct and dense CB1 receptor expression within these areas. Overall, our results demonstrate that, depending on dosage, CB1 agonism can both inhibit and stimulate neuronal activity within brain regions controlling adult vocal motor output, implicating involvement of multiple CB1-sensitive neuronal circuits. Originally published Psychopharmacology, Vol. 199, No. 2, Aug 200