The role of action potentials in the development of proper synaptic connections in the mammalian CNS was studied in the kitten retinogeniculate pathway. Our basic finding is that there is improper segregation of retinal inputs onto LGN cells after prolonged retinal action-potential blockade. Retinal ganglion cell firing was silenced from birth by repeated monocular injections of TTX. The resulting ganglion cell connections in the LGN were studied electrophysiologically after the action-potential blockade was ended. Most cells in the deprived LGN layers received excitatory input from both ON-center and OFF-center type ganglion cells, whereas LGN cells normally receive inputs only from ON-center or OFF-center ganglion cells, but not from both types. Improper segregation of ON and OFF inputs has never been reported after other types of visual deprivation that do not block ganglion cell activity. Control experiments showed that receptive fields in the nondeprived LGN layers were normal, that ganglion cell responses remained normal, and that there was no obvious ganglion cell loss. We also showed that individual LGN cells with ON and OFF excitatory inputs were not present in normal neonatal kittens. Two other types of improper input segregation in response to action-potential blockade were also found in the deprived LGN layers. (1) A greater than normal number of LGN cells received both X- and Y-type ganglion cell input. (2) Almost half of the cells at LGN layer borders were excited binocularly. Recovery of LGN normality was rapid and complete after blockade that lasted for only 3 weeks from birth, but little recovery was seen after about 11 weeks of blockade. The susceptibility to action-potential blockade decreased during the first 3 postnatal weeks. These findings may result from axon-terminal sprouting or from the failure of axon terminals to retract. The results are consistent with the idea that normally synchronous activity of neighboring ganglion cells of like center-type may be used in the refinement of retinogeniculate synaptic connections.

WHAT'S KNOWN ON THIS SUBJECT:The retention and use of residual bloodspots is a practice of many state newborn screening programs. This practice has become controversial, and little is known about public attitudes on the retention and research use of newborn residual bloodspots. WHAT THIS STUDY ADDS:This study offers a detailed analysis of public attitudes regarding bloodspot retention and use for biomedical research. The results also offer insights on how education regarding this practice influences support for newborn screening and residual bloodspot use. abstract BACKGROUND AND OBJECTIVES: Many state newborn screening (NBS) programs retain residual NBS bloodspots after the completion of screening. Potential uses for residual specimens include laboratory quality assurance, biomedical research, and, rarely, forensic applications. Our objective was to evaluate public opinion about the policies and practices relevant to the retention and use of residual bloodspots for biomedical research. METHODS:A total of 3855 respondents were recruited using 3 methods: focus groups (n = 157), paper or telephone surveys (n = 1418), and a Knowledge Networks panel (n = 2280). Some participants (n = 1769) viewed a 22-minute movie about the retention and use of residual specimens while other participants were provided only written information about this practice. All participants were surveyed using a 38-item questionnaire. RESULTS:A diverse set of participants was recruited. Respondents were very supportive of NBS in general and accepting of the use of residual bloodspots for important research activities. Respondents were evenly divided on the acceptability of NBS without parental permission, but the majority of respondents supported the use of an "optin" process for parental permission for residual bloodspot retention and use. Viewing the educational movie was associated with greater support for bloodspot retention and use. CONCLUSIONS:Our results show that the general public surveyed here was supportive of NBS and residual sample retention and research use. However, there was a clear preference for an informed permission process for parents regarding these activities. Education about NBS was associated with a higher level of support and may be important to maintain public trust in these important programs.

A pilot study assessed an electronic informed consent model within a randomized controlled trial (RCT). Participants who were recruited for the parent RCT project were randomly selected and randomized to either an electronic consent group (n = 32) or a simplified paper-based consent group (n = 30). Results from the electronic consent group reported significantly higher understanding of the purpose of the study, alternatives to participation, and who to contact if they had questions or concerns about the study. However, participants in the paper-based control group reported higher mean scores on some survey items. This research suggests that an electronic informed consent presentation may improve participant understanding for some aspects of a research study.

This paper discusses attitudes and opinions of a diverse group of participants toward the retention and use of residual newborn blood samples for research. Data were drawn from focus groups based in six states in the USA, and results provide support for the retention and use of residual newborn blood samples for research when parental permission is asked beforehand. However, there were a number of concerns that also warrant attention for the development of policy and maintaining trust with the public, such as timing of permission, use of samples already stored, level of personal control of sample use and education. The results demonstrate the complexity of the topic and the ethical ambiguities associated with the retention and use of residual newborn blood samples.

Although the influence of electrical activity on neural development has been studied extensively, experiments have only recently focused on the role of activity in the development of the mammalian central nervous system (CNS). Using tetrodotoxin (TTX) to abolish sodium-mediated action potentials, studies on the visual system show that impulse activity is essential both for the normal development of neuronal size and responsivity in the lateral geniculate nucleus (LGN), and for the eye-specific segregation of geniculo-cortical axons. There have been no anatomical studies to investigate the influence of action potentials on CNS synaptic development. We report here the first direct evidence that elimination of action potentials in the mammalian CNS blocks the growth of developing axon terminals and the formation of normal adult synaptic patterns. Our results show that when TTX is used to eliminate retinal ganglion-cell action potentials in the cat from birth to 8 weeks, the connections made by ganglion cell axons with LGN neurones, retinogeniculate synapses, remain almost identical morphologically to those in the newborn kitten.