Table 3.
Supraspinal projections of phrenic afferent neurons
| Location | Method/Species | Comment | Citations |
|---|---|---|---|
| Dorsal columns | Tract tracing and histology, rat; neurophysiology, cat | Phr afferent fibers clearly observed in dorsal columns; Phr E-stim evokes cord dorsum potentials | Chou and Davenport (2005); Goshgarian and Roubal (1986); Larnicol et al. (1984); Nair et al. (2017) |
| Outside of dorsal column | Neurophysiology, cat | Dorsal column lesion does not abolish VRG responses following Phr E-stim | Speck and Revelette (1987b) |
| Cervical spinothalamic tract | Neurophysiology, monkey | Phr E-stim or punctate mechanical stimulation of the diaphragm activates or inhibits STT neurons | Bolser et al. (1991a, 1991b) |
| External cuneate | Neurophysiology and tracing, cat | Monosynaptic connections from group I–II afferents | Larnicol et al. (1985); Marlot et al. (1985) |
| Nucleus of solitary tract | c-Fos in rat | Direct connections are unknown? | Malakhova and Davenport (2001) |
| Ventrolateral reticular formation | Neurophysiology, cats | Nucleus ambiguous discharge pattern was strongly affected by Phr E-stim; concluded that Phr afferents relay in VLRN before projecting to the cerebellar cortex | Macron et al. (1985); Malakhova and Davenport (2001) |
| Dorsal respiratory group | Neurophysiology, cat | Strong connections, hypothesized to be from group III | Speck and Revelette (1987b) |
| Ventral respiratory group | Neurophysiology in cat; c-Fos in rat | Weak connection | Malakhova and Davenport (2001); Speck and Revelette (1987b) |
| Hypothalamus | c-Fos in rat | Malakhova and Davenport (2001) | |
| Thalamus | Neurophysiology, cat, rat; histology, rats | Phr E-stim and diaphragm mechanical stim activates contralateral VPL neurons; |
Malakhova and Davenport (2001); Zhang and Davenport (2003) |
| paraventricular thalamic nucleus has c-fos expression following Phr stimulation | |||
| Cerebellar cortex | Neurophysiology, cat | E-stim of C5–C6 Phr branches evokes cerebellar cortex potentials; ascending fibers are in contralateral ventrolateral spinal cord | Marlot et al. (1984, 1985) |
| Cingulate gyrus | Neurophysiology, human | Evoked potentials in anterior cingulate gyrus with transcutaneous Phr E-stim | Straus et al. (1997) |
| Amygdala | Histology, rat | Central nucleus of amygdala has c-fos expression following Phr E-stim | |
| Somatosensory cortex | Neurophysiology, human, cat, and rat | Cortical evoked potentials from Phr E-stim in cats and rats. Brief inspiratory occlusion in humans evokes somatosensory cortex EEG response | Davenport et al. 1985, 1986, 2006, 2010); Frankstein et al. (1979); Revelette and Davenport (1990); Yates et al. (1994) |
Listed are key publications that provide evidence for the location of ascending pathways containing phrenic afferent information, as well as the potential destination of pathways from diaphragm receptors. VRG, ventral respiratory group; STT, spinothalamic tract; VLRN, ventrolateral reticular formation; VPL, ventral posterolateral nucleus.