| Title | Convergence of cranial visceral afferents within the solitary tract nucleus. | | Author(s) | McDougall SJ, Peters JH, Andresen MC | | Institution | Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239-3098, USA. stuart.mcdougall@gmail.com | | Source | J Neurosci 2009 Oct 14; 29(41):12886-95. | | MeSH | Afferent Pathways
Analysis of Variance
Animals
Biophysics
Brain Mapping
Electric Stimulation
Excitatory Postsynaptic Potentials
Nerve Net
Neurons, Afferent
Patch-Clamp Techniques
Rats
Rats, Sprague-Dawley
Reaction Time
Solitary Nucleus
Synapses
| | Abstract | Primary afferent axons within the solitary tract (ST) relay homeostatic information via glutamatergic synapses directly to second-order neurons within the nucleus of the solitary tract (NTS). These primary afferents arise from multiple organ systems and relay multiple sensory modalities. How this compact network organizes the flow of primary afferent information will shape central homeostatic control. To assess afferent convergence and divergence, we recorded ST-evoked synaptic responses in pairs of medial NTS neurons in horizontal brainstem slices. ST shocks activated EPSCs along monosynaptic or polysynaptic pathways. Gradations in shock intensity discriminated multiple inputs and stimulus recruitment profiles indicated that each EPSC was unitary. In 24 pairs, 75% were second-order neurons with 64% receiving one direct ST input with the remainder receiving additional convergent ST afferent inputs (22% two; 14% three monosynaptic ST-EPSCs). Some (34%) second-order neurons received polysynaptic EPSCs. Neurons receiving only higher-order inputs were uncommon (13%). Most ST-EPSCs were completely independent, but 4 EPSCs of a total of 81 had equal thresholds, highly correlated latencies, and synchronized synaptic failures consistent with divergence from a single source ST axon or from a common interneuron producing a pair of polysynaptic EPSCs. We conclude that ST afferent inputs are remarkably independent with little evidence of substantial shared information. Individual cells receive highly focused information from the viscera. Thus, afferent excitation of second-order NTS neurons is generally dominated by single visceral afferents and therefore focused on a single afferent modality and/or organ region. | | Language | eng | | Pub Type(s) | In Vitro
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
| | PubMed ID | 19828803 |
|
