Response characteristics of cerebellar nuclear cells in the pigeon

Update of model to predict sensible heat loss in broilers

The present study was conducted to adjust and adapt some parameters of the model of production and heat loss by convection and conduction, so as to predict the actual feed intake (aFI) of broilers reared in sheds. The re-parameterised models were the sensible heat loss by convection from surface (HS) and by conduction (HC) in birds. The HS model was re-parameterised to calculate the heat loss of poultry reared in sheds and the parameters of thermal resistance of feathers (RF) and skin (RS) of poultry were inserted. The HC model was re-parameterised for birds in sheds and the RF, RS and the thermal resistance of the litter (R) were inserted. The re-parameterised HS model was HS = [A × QV × (TB – TA)]/[(TB – 17) × (RF + RS)], where TA is the air temperature, QV is the volume factor, TB is the surface temperature of the bird (°C) and A was estimated to be 11.94 watts (W). The values found in the model ranged from 0.75 W for birds with 100 g BW subjected to 33°C TA, 50% HU, 0.1 m/s wind speed (V) and 12.53 W for birds with 4100 g subjected to 33°C TA, 80% HU and 0.1 m/s V. The values found in the re-parameterised HC model (HC = [(TB – TC) × k × AR × QA]/[L × (RF + RS + R)], where K is the thermal conductivity of the litter, AR is the contact area of bird with the litter and QA is the area factor, and L is the litter height) ranging from 0.017 W to chickens with 100 g BW in comfortable conditions and 0.17 W for birds with 4100 g in thermal discomfort condition. The present study showed that the re-parameterisation of heat-loss equations is more accurate to predict the heat flux in broilers under different environmental conditions.

Recovery of motor and cognitive function after cerebellar lesions in a songbird: role of estrogens

In addition to its key role in complex motor function, the cerebellum is increasingly recognized to have a role in cognition. Songbirds are particularly good models for the investigation of motor and cognitive processes but little is known about the role of the songbird cerebellum in these processes. To explore cerebellar function in a songbird, we lesioned the cerebellum of adult female zebra finches and examined the effects on a spatial working memory task and on motor function during this task. There is evidence for steroid synthesis in the songbird brain and neurosteroids may have an impact on some forms of neural plasticity in adult songbirds. We therefore hypothesized that neurosteroids would affect motor and cognitive function after a cerebellar injury. We found that cerebellar lesions produced deficits in motor and cognitive aspects of a spatial task. In line with our prediction, birds in which estrogen synthesis was blocked had impaired performance in our spatial task compared with those that had estrogen synthesis blocked but estrogen replaced. There was no clear effect of estrogen replacement on motor function. We also found that lesions induced expression of the estrogen synthetic enzyme aromatase in reactive astrocytes and Bergmann glia around a cerebellar lesion. These data suggest that the cerebellum of songbirds mediates both motor and cognitive function and that estrogens may improve the recovery of cognitive aspects of cerebellar function after injury.