Cranial visceral afferents enter the brain at the solitary tract nucleus (NTS). -aminobutyric acid (GABAergic) neurons are scattered throughout NTS, but their relation to solitary tract (ST) afferent pathways is imprecisely known. We hypothesized that most GABAergic NTS neurons would be connected only indirect to the ST. We identified GABAergic neurons in brainstem horizontal slices using transgenic mice in which enhanced green fluorescent protein (EGFP) expression was linked to glutamic acid decarboxlyase expression (GAD⁺). Finely graded electrical shocks to ST recruited ST-synced synaptic events with all-or-none thresholds and individual waveforms did not change with greater suprathreshold intensities — evidence consistent with initiation by single afferent axons. Most (~70%) GAD⁺ neurons received ST-evoked excitatory postsynaptic currents (EPSCs) that had minimally variant latencies (jitter, standard deviation of latency <200 µsec) and waveforms consistent with single, direct ST connections (i.e. monosynaptic). Increasing stimulus intensity evoked additional ST-synced synaptic responses with jitters >200 µsec including inhibitory postsynaptic currents (IPSCs) indicating indirect connections (polysynaptic). Shocks of suprathreshold intensity delivered adjacent (50-300 µm) to the ST failed to excite non-ST inputs to second-order neurons suggesting a paucity of axons passing near to ST that connected to these neurons. Despite expectations, we found similar ST synaptic patterns in GAD⁺ and unlabeled neurons. Generally, ST information that arrived indirectly had small amplitudes (EPSCs and IPSCs) and frequency-dependent failures that reached >50% for IPSCs to bursts of stimuli. This ST afferent pathway organization is strongly use-dependent — a property that may tune signal propagation within and beyond NTS.