BDNF increases BrdU-IR cells in the injured adult zebra finch hippocampus.

Steroid-mediated cell proliferation, differentiation, and survival can be triggered by learning, experience, and brain injury. In the uninjured canary song system, testosterone induces cell proliferation that is blocked by an antibody to brain-derived neurotrophic factor (BDNF). However, little is known with regard to the effects of neurotrophic factors on injury-induced cell proliferation and incorporation.

Aromatase expression and cell proliferation following injury of the adult zebra finch hippocampus.

Estrogens can be neuroprotective following traumatic brain injury. Immediately after trauma to the zebra finch hippocampus, the estrogen-synthetic enzyme aromatase is rapidly upregulated in astrocytes and radial glia around the lesion site. Brain injury also induces high levels of cell proliferation.

Estrogen mediation of injury-induced cell birth in neuroproliferative regions of the adult zebra finch brain.

Estrogens influence neuronal differentiation, migration, and survival in intact brains. In injured brains, estrogens can also be neuroprotective. In Experiment 1, following a unilateral penetrating injury to the hippocampus (HP), adult female zebra finches were injected once with BrdU to label mitotic cells then sacrificed 2 h, 1 day, or 7 days postinjection.

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.

Radial glia express aromatase in the injured zebra finch brain.

Estrogens have neurotrophic and neuroprotective properties. The synthesis of estrogen occurs via the expression of aromatase. Previous studies have shown that injury to the vertebrate brain results in a rapid and dramatic up-regulation of aromatase expression in astrocytes around the lesion.

Revised nomenclature for avian telencephalon and some related brainstem nuclei.

The standard nomenclature that has been used for many telencephalic and related brainstem structures in birds is based on flawed assumptions of homology to mammals. In particular, the outdated terminology implies that most of the avian telencephalon is a hypertrophied basal ganglia, when it is now clear that most of the avian telencephalon is neurochemically, hodologically, and functionally comparable to the mammalian neocortex, claustrum, and pallial amygdala (all of which derive from the pallial sector of the developing telencephalon). Recognizing that this promotes misunderstanding of the functional organization of avian brains and their evolutionary relationship to mammalian brains, avian brain specialists began discussions to rectify this problem, culminating in the Avian Brain Nomenclature Forum held at Duke University in July 2002, which approved a new terminology for avian telencephalon and some allied brainstem cell groups.

The Avian Brain Nomenclature Forum: Terminology for a New Century in Comparative Neuroanatomy.

Many of the assumptions of homology on which the standard nomenclature for the cell groups and fiber tracts of avian brains have been based are in error, and as a result that terminology promotes misunderstanding of the functional organization of avian brains and their evolutionary relationship to mammalian brains. Recognizing this problem, a number of avian brain researchers began an effort to revise the terminology, which culminated in the Avian Brain Nomenclature Forum, held at Duke University from July 18 to 20, 2002. In the new terminology approved at this Forum, the flawed conception that the telencephalon of birds consists nearly entirely of a hypertrophied basal ganglia has been purged from the telencephalic terminology, and the actual parts of the basal ganglia and its brainstem afferent cell groups have been given names reflecting their now evident homologies.