Sequential Organization of Critical Periods in the Mouse Auditory System.

Critical periods-time windows of heightened plasticity in postnatal development-are specific to sensory features and are asynchronous. Whether they are timed by a temporally precise developmental program or are sequentially organized is not known. We use electrophysiology and molecular or sensory manipulations to elucidate the biological constraints on critical period timing.

A Late Critical Period for Frequency Modulated Sweeps in the Mouse Auditory System.

Neuronal circuits are shaped by experience during time windows of increased plasticity in postnatal development. In the auditory system, the critical period for the simplest sounds-pure frequency tones-is well defined. Critical periods for more complex sounds remain to be elucidated.

Matrix metalloproteinases as promising regulators of axonal regrowth in the injured adult zebrafish retinotectal system.

Overcoming the failure of axon regeneration in the mammalian central nervous system (CNS) after injury remains a major challenge, which makes the search for proregenerative molecules essential. Matrix metalloproteinases (MMPs) have been implicated in axonal outgrowth during CNS development and show increased expression levels during vertebrate CNS repair. In mammals, MMPs are believed to alter the suppressive extracellular matrix to become more permissive for axon regrowth.

Decreased thyroid hormone signaling accelerates the reinnervation of the optic tectum following optic nerve crush in adult zebrafish.

The regenerative capacity of the adult mammalian central nervous system (CNS) is poor and finding ways to stimulate long distance axonal regeneration in humans remains a challenge for neuroscientists. Thyroid hormones, well known for their key function in CNS development and maturation, more recently also emerged as molecules influencing regeneration. While several studies investigated their influence on peripheral nerve regeneration, in vivo studies on their role in adult CNS regeneration remain scarce.

Role of thyroid hormones in different aspects of nervous system regeneration in vertebrates.

Spontaneous functional recovery from injury in the adult human nervous system is rare and trying to improve recovery remains a clinical challenge. Nervous system regeneration is a complicated sequence of events involving cell death or survival, cell proliferation, axon extension and remyelination, and finally reinnervation and functional recovery. Successful recovery depends on the cell-specific and time-dependent activation and repression of a wide variety of growth factors and guidance molecules.