Summary
A total of 66 taste and 33 mechanoreceptive neurons were isolated from the parabrachial nucleus (PB) of rats. Among them, 39 taste and 8 mechanoreceptive neurons were identified as parabrachio-thalamic relay (P-T) neurons on the basis of antidromic activation from either or both sides of the thalamic taste areas (TTAs). On average, the P-T taste neurons produced larger response magnitudes than the non-P-T taste neurons, and whereas about half the P-T taste neurons were NaCl-best, only a small number of the non-P-T taste neurons were NaCl-best. Both the P-T and non-P-T taste neurons showed a similar breadth of responsiveness to four basic taste stimuli. The response magnitudes of the P-T taste neurons to all taste stimuli were ca. 3 times larger than those of the solitario-parabrachial relay (SP) neurons (afferents to the PB); in particular, the response magnitudes of the NaCl-best P-T neurons were 4–5 times larger than those of the NaCl-best SP neurons. The response magnitudes and breadth of taste responsiveness of the P-T taste neurons were reciprocally correlated with the antidromic latencies from either side of the TTAs. A histological examination revealed that the P-T taste neurons in the ventral part of the PB had a shorter antidromic latency from the ipsilateral TTA than those in the dorsal part of the nucleus. Mechanoreceptive neurons were excited by stroking the tissue in the oral cavity or perioral tissue, or by pinching them with non-serrated forceps. The mechanoreceptive P-T neurons were also activated from either or both sides of the TTAs. No particular relation was noticed between the antidromic latency of the mechanoreceptive P-T neurons and their response properties or locations in the nucleus.
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References
Ables MF, Benjamin R (1960) Thalamic relay nucleus for taste in albino rat. J Neurophysiol 23: 376–382
Bishop PO, Burke W, Davis R (1962) The identification of single units in central visual pathways. J Physiol (Lond) 162: 409–431
Erickson RP (1963) Sensory neural patterns and gustation. In: Zotterman Y (ed) Olfaction and taste. Pergamon Press, Oxford London New York Paris (Werner-Gren center international symposium series, Vol I), pp 205–213
Frank ME, Contreras RJ, Hettinger TP (1983) Nerve fibers sensitive to ionic taste stimuli in chorda tympani of the rat. J Neurophysiol 50: 941–960
Fukuda Y, Stone J (1974) Retinal distribution and central projections of Y-, X-, and W-cells of the cat's retina. J Neurophysiol 37: 749–772
Hayama T, Ito S, Ogawa H (1983) Projections of the parabrachial taste neurons to the thalamus and the amygdala. J Physiol Soc Jpn 45: 498
Lasiter PS, Glanzman DL (1983) Axon collaterals of pontine taste area neurons project to the posterior ventrothalamic nucleus and to the gustatory neocortex. Brain Res 258: 299–304
Lund RD, Webster KE (1967) Thalamic afferents from spinal cord and trigeminal nuclei. An experimental anatomical study in rat. J Comp Neurol 130: 313–328
Nomura T, Ogawa H (1985) The taste and mechanical response properties of neurons in the parvicellular part of the thalamic posteromedial ventral nucleus of the rat. Neurosci Res 3: 91–105
Norgren R (1974) Gustatory afferents to ventral forebrain. Brain Res 81: 285–295
Norgren R (1978) Projections from the nucleus of the solitary tract in the rat. Neuroscience 3: 207–218
Norgren R, Leonard CM (1974) Ascending central gustatory pathways. J Comp Neurol 150: 217–238
Ogawa H, Akagi T (1978) Afferent connections to the posteromedial ventral nucleus from the pons and the rostral medulla in the rat. Kumamoto Med J 31: 54–62
Ogawa H, Hayama T (1984) Receptive fields of solitario-parabrachial relay neurons responsive to natural stimulation of the oral cavity in rats. Exp Brain Res 54: 359–366
Ogawa H, Hayama T, Ito S (1984a) Location and taste responses of parabrachio-thalamic relay neurons in rats. Exp Neurol 83: 507–517
Ogawa H, Imoto T, Hayama T (1984b) Responsiveness of solitario-parabrachial relay neurons to taste and mechanical stimulation applied to the oral cavity in rats. Exp Brain Res 54: 349–358
Perroto RS, Scott TR (1976) Gustatory neural coding in the pons. Brain Res 110: 283–300
Sato M, Ogawa H, Yamashita S (1975) Response properties of macaque monkey chorda tympani fibers. J Gen Physiol 66: 781–810
Smith DV, Travers JB (1979) A metric for the breadth of tuning of gustatory neurons. Chem Sens Flav 4: 215–229
Smith RL (1973) The ascending fiber projections from the principal sensory trigeminal nucleus in the rat. J Comp Neurol 148: 423–436
Stone J, Fukuda Y (1974) Properties of cat retinal ganglion cells: a comparison of W-cells with X- and Y-cells. J Neurophysiol 37: 722–748
Voshart K, van der Kooy D (1981) The organization of the efferent projections of the parabrachial nucleus to the forebrain in the rat: a retrograde fluorescent double-labelling study. Brain Res 212: 271–286
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Ogawa, H., Hayama, T. & Ito, S. Response properties of the parabrachio-thalamic taste and mechanoreceptive neurons in rats. Exp Brain Res 68, 449–457 (1987). https://doi.org/10.1007/BF00249789
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DOI: https://doi.org/10.1007/BF00249789