Activation of NMDA Receptors Is Necessary for the Recovery of Cortical Binocularity

Classic experiments have indicated that monocular deprivation (MD) for a few days during a critical period of development results in a decrease in the strength of connections mediating responses to the deprived eye, leading to a dramatic breakdown of cortical neuron binocularity. Despite the substantial functional change in the visual cortex, recovery from the effects of MD can be obtained if binocular vision is promptly restored. While great efforts have been made to elucidate the mechanisms regulating loss of deprived eye function, the mechanisms that underlie the recovery of cortical binocularity are poorly understood. Here, we examined whether activation of the N-methyl-d-aspartate receptor (NMDAR) is required for the recovery of cortical binocularity by pharmacologically blocking the NMDAR using d,l-2-amino-5-phosphonopentanoic (APV). Ferrets ( n = 10) were monocularly deprived for 6 days, and osmotic minipumps, filled with APV (5.6 mg/ml) or saline, were surgically implanted into the primary visual cortex. One day after surgery, the deprived eye was reopened, and the animals were allowed 24 h of binocular vision. Extracellular recordings showed that intracortical infusion of the NMDAR antagonist, APV, prevented recovery of cortical binocularity while preserving neuronal responsiveness. These findings provide an important new insight for a specific role of NMDARs in the recovery of cortical binocularity from the effects of MD.

Helping Children Transition from Kindergarten to First Grade

This article documents the challenges that young children face as they move from kindergarten to first grade and the important role that elementary school counselors can play in working with students, parents/caregivers, and teachers during this critical period of development. Research- and practitioner-based recommendations for effective interventions are discussed.

Nitrogenous metabolism in Thoroughbred and Arabian foals from birth to five months of age

The maturation of nitrogen metabolism was studied in six Thoroughbred and six Arabian foals. Rectal temperature, heart and respiratory rates and serum concentration of several hematochemical parameters (total protein, urea, uric acid, creatinine, and albumine) were monitored from birth to 5 months of age. In both breeds, all the parameters except albumine showed significant differences over time (P<0.05). The two breeds did not differ from each other at any time point. Statistically significant decreases in urea and creatinine concentrations were related to the growth needs of foals during this critical period of development.