Early Nerve Injury May Permanently Alter Sensory Input to the Brain
While adults have difficulty recovering following injury to the brain, children show remarkable restoration of neural function after similar types of damage. The opposite is often true in the peripheral nervous system, however. For instance, the nerve that relays taste information from the front of the tongue to the brain, the chorda tympani nerve (CT), regenerates several weeks after it is surgically cut (CTX) in adult rats. Consequently, these animals experience an almost complete recovery of sensory function and taste-guided behavior. On the other hand, previous studies from our lab have shown that when CTX occurs 10 days after birth, the nerve fails to regenerate, taste buds innervated by the CT permanently disappear, and these rats gain abnormal taste preferences. The current study was performed to understand how the physiology of the taste system is altered after CTX in young rats. To test this, electrophysiological responses following taste stimulation were recorded in the nerve that innervates taste buds on the back of the tongue, the glossopharyngeal nerve (GL), two months after cutting the CT in 10-day-old rats. Additionally, taste responses from the CT were recorded one year after the contralateral CT was sectioned during this early developmental period. Rats with CTX had lower neural responses when sodium chloride (NaCl) solutions were applied to the tongue compared to control animals. This result shows that there may be a permanent decrease in receptors for sodium salts on the tongue after early CTX – even on areas of the tongue where the nerve is not present. Thus, there are likely circulating factors (such as neurotrophins or immune components) that affect receptors across the tongue when an injury occurs. Unlike the results of this study in neonates, adult CTX does not alter nerve responses, showing again the greater susceptibility of the developing taste system to injury. This suggests that developing animals are more susceptible to impaired function after neural injury. CT injury is not a rare occurrence in children; it can happen as a result of ear surgery or ear infections. The results of this study provide insight into potential mechanisms behind long-term taste alterations that can occur after such CT injury.
A full copy of the paper can be found here.
The study of the biological basis of behavior is one of the most rapidly growing
areas of life sciences, reflecting the importance of the fundamental and applied interest in how neurons work on an individual basis, and how collections of neurons mediate behavior and cognition.
The College of Arts and Sciences at UNO has established the first undergraduate neuroscience degree program in the Nebraska system to educate students bound for graduate programs in neuroscience as well as various careers in the health or health-related fields.
Students working toward completion of this degree will benefit from the expertise of existing faculty in the UNO departments of Biology and Psychology along one of two tracks: Molecular and Cellular Neuroscience or Integrative Behavioral Science.
An undergraduate major in neuroscience will place students in the position of
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