There is considerable evidence that competitive interactions play a major role in determining the both the morphological properties of, and distributions of functional synapses made by, afferents to a given central nervous system nucleus. However, it is not at all clear whether this is the case with respect to the trigeminal (V) primary innervation of the rat's brainstem. In fact, limited evidence (Belford and Killackey, '80; Durham and Woolsey, '84) has suggested that such interactions may play little or no role in the postnatal development of this pathway. We will determine whether competitive interactions influence either the pre- and/or postnatal development of V primary afferents by carrying out three experiments. First, we will use anterograde transport of Di-I and horseradish peroxidase (HRP) to label individual V primary afferents in both fetal and neonatal rats. These fibers will be reconstructed in the light microscope and distributions of synapses made by single axons will be determined by electron microscopy. Secondly, we will record from individual V primary afferents and neurons in V nucleus principalis (PrV) in fetal and newborn rats to determine whether the latter cells receive greater convergent input than is the case in adult animals. The results of these two studies will allow us to determine whether the substrate for competitive interactions among V primary afferents exists in fetal or early postnatal life. In a third and final experiment, we will use fetal surgical techniques to damage the peripheral axons of primary afferents that innervate selected vibrissae follicles. If competitive interactions shape the central arbors of vibrissa-related primary afferents, such lesions should put undamaged axons at a """"""""competitive advantage"""""""" and increase the size of their central terminal arbors. We will use intra-axonal recording and HRP injection techniques to determine whether or not this occurs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS028888-02
Application #
3415583
Study Section
Neurology B Subcommittee 2 (NEUB)
Project Start
1990-08-01
Project End
1995-07-31
Budget Start
1991-08-01
Budget End
1992-07-31
Support Year
2
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Toledo
Department
Type
Schools of Medicine
DUNS #
807418939
City
Toledo
State
OH
Country
United States
Zip Code
43614
Chiaia, N L; Shah, A; Crissman, R S et al. (2001) Prevention of galanin upregulation following neonatal infraorbital nerve transection or attenuation of axoplasmic transport does not rescue central vibrissae-related patterns in the rat. Eur J Neurosci 13:25-34
Stojic, A S; Lane, R D; Rhoades, R W (2001) Intracortical pathway involving dysgranular cortex conveys hindlimb inputs to S-I forelimb-stump representation of neonatally amputated rats. J Neurophysiol 85:407-13
Stojic, A S; Lane, R D; Killackey, H P et al. (2000) Suppression of hindlimb inputs to S-I forelimb-stump representation of rats with neonatal forelimb removal: GABA receptor blockade and single-cell responses. J Neurophysiol 83:3377-87
Chiaia, N L; Zhang, S; Crissman, R S et al. (2000) Effects of neonatal axoplasmic transport attenuation on the response properties of vibrissae-sensitive neurons in the trigeminal principal sensory nucleus of the rat. Somatosens Mot Res 17:273-83
Lane, R D; Stojic, R S; Killackey, H P et al. (1999) Source of inappropriate receptive fields in cortical somatotopic maps from rats that sustained neonatal forelimb removal. J Neurophysiol 81:625-33
Stojic, A S; Lane, R D; Killackey, H P et al. (1998) Thalamocortical and intracortical projections to the forelimb-stump SI representation of rats that sustained neonatal forelimb removal. J Comp Neurol 401:187-204
Bodie, D; Bennett-Clarke, C A; Davis, K et al. (1997) Organization, development, and effects of infraorbital nerve transection on galanin binding sites in the trigeminal brainstem complex. Somatosens Mot Res 14:168-80
Lane, R D; Killackey, H P; Rhoades, R W (1997) Blockade of GABAergic inhibition reveals reordered cortical somatotopic maps in rats that sustained neonatal forelimb removal. J Neurophysiol 77:2723-35
Chiaia, N L; Bennett-Clarke, C A; Crissman, R S et al. (1997) Long-term effects of neonatal axoplasmic transport attenuation on the organization of the rat's trigeminal system. J Comp Neurol 381:219-29
Rhoades, R W; Crissman, R S; Bennett-Clarke, C A et al. (1996) Development and plasticity of local intracortical projections within the vibrissae representation of the rat primary somatosensory cortex. J Comp Neurol 370:524-35

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