Abstract
Learned heart rate changes were assessed during two sessions of differential Pavlovian (classical) conditioning in three groups of New Zealand albino rabbits. One group received ibotenic acid lesions of the midline nuclei of the thalamus, a second received vehicle injections in the midline nuclei, and a third group served as unoperated control animals. During an initial session, the cardiac component of the orienting reflex was assessed in all three groups. The rabbits with lesions of midline thalamic nuclei demonstrated enhanced bradycardiac conditioned responses, relative to either vehicle-control or unoperated animals. The heart rate component of the orienting response to nonreinforced tones, which also consisted of stimulus-evoked bradycardia, was likewise larger in lesioned animals. These results suggest that the midline thalamic nuclei, like the interconnected mediodorsal thalamic nucleus, may be involved in the regulation of sympathetically mediated autonomic adjustments.
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Aggleton, J. P., & Mishkin, M. (1983). Memory impairments following restricted medial thalamic lesions in monkeys. Experimental Brain Research, 52, 199–209.
Albiniak, A. B., & Powell, D. A. (1980). Peripheral autonomic mechanisms and Pavlovian conditioning in the rabbit (Oryctolagus cuniculus). Journal of Comparative & Physiological Psychology, 94, 1101–1113.
Brutus, M., Watson, R. E., Shaikh, M. B., Siegel, H. E., Weiner, S., & Siegel, A. (1984). A (p14C)2-deoxyglucose analysis of the functional neural pathways of the limbic forebrain in the rat: 4. A pathway from the prefrontal cortical-medial thalamic system to the hypothalamus. Brain Research, 310, 279–293.
Buchanan, S. L. (1988). Mediodorsal thalamic lesions impair differential Pavlovian heart rate conditioning. Experimental Brain Research, 73, 320–328.
Buchanan, S., & Powell, D. A. (1986). Electrical stimulation of anteromedial and mediodorsal thalamus elicits differential cardiovascular response patterns from conscious rabbits. Physiological Psychology, 14, 115–123.
Buchanan, S. L., & Powell, D. A. (1987). p3H-2-deoxyglucose uptake following stimulation of cardioactive sites in insular cortex and mediodorsal nucleus of the thalamus in rabbits. Brain Research Bulletin, 19, 439–452.
Buchanan, S. L., & Powell, D. A. (1989). Parasagittal thalamic knife cuts and cardiac changes. Behavioral Brain Research, 32, 241–253.
Huang, Z.-S., Varner, K. J., Barman, S. M., & Gebber, G. L. (1988). Diencephalic regions contributing to sympathetic nerve discharge in anesthetized cats. American Journal of Physiology, 254, R249–R256.
Markowitsch, H. J. (1982). Thalamic mediodorsal nucleus and memory: A critical evaluation of studies in animals and man. Neuroscience & Biobehavioral Reviews, 6, 351–380.
Powell, D. A., & Buchanan, S. L. (1986). Autonomic changes elicited by chemical stimulation of the mediodorsal nucleus of the thalamus. Pharmacology, Biochemistry & Behavior, 25, 423–430.
Squire, L. R. (1981). Two forms of human amnesia: An analysis of forgetting. Journal of Neuroscience, 1, 635–640.
Urban, U., & Richard, P. A. (1972). A stereotaxic atlas of the New Zealand rabbit. Springfield, IL: Thomas.
Varner, K. J., Barman, S. M., & Gebber, G. L. (1988). Cat diencephalic neurons with sympathetic nerve-related activity. American Journal of Physiology, 254, R257–R267.
West, C. H. K., & Benjamin, R. M. (1983). Effects of stimulation of the mediodorsal nucleus and its projection cortex on heart rate in the rabbit. Journal of the Autonomic Nervous System, 9, 547–557.
West, C. H. K., Jackson, J. C, & Benjamin, R. M. (1979). An autoradiographic study of subcortical forebrain projections from mediodorsal and adjacent midline thalamic nuclei in the rabbit. Neuroscience, 4, 1977–1988.
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This research was supported by VA Institutional Research Funds awarded to the Wm. Jennings Bryan Dorn VA Medical Center.
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Buchanan, S.L., Thompson, R.H. & Powell, D.A. Midline thalamic lesions enhance conditioned bradycardia and the cardiac orienting reflex in rabbits. Psychobiology 17, 300–306 (1989). https://doi.org/10.1007/BF03337784
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DOI: https://doi.org/10.1007/BF03337784