Intracellular recording of magnocellular preoptic neuron responses to olfactory brain

• Published in: Neuroscience Vol. 78; no. 1; pp. 229 - 242
• Main Authors: Paolini, A.G, McKenzie, J.S
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-05-1997; Elsevier
• Subjects: Animals; Biological and medical sciences; Electric Stimulation; Electrophysiology; entorhinal area; Evoked Potentials - drug effects; Evoked Potentials - physiology; Fundamental and applied biological sciences. Psychology; Globus Pallidus - cytology; Globus Pallidus - physiology; Image Processing, Computer-Assisted; in vivo intracellular recording; magnocellular preoptic nucleus; Male; Microelectrodes; Neostriatum - cytology; Neostriatum - physiology; Neurons - physiology; olfactory bulb; Olfactory Bulb - cytology; Olfactory Bulb - physiology; Olfactory system and olfaction. Gustatory system and gustation; piriform cortex; Preoptic Area - cytology; Preoptic Area - physiology; Rats; Vertebrates: nervous system and sense organs; olfactory bulb; PC, piriform cortex; piriform cortex; in vivo intracellular recording; OB, olfactory bulb; HDB, horizontal limb of the diagonal band; EPSP, excitatory postsynaptic potential; magnocellular preoptic nucleus; EA, entorhinal area; MCPO, magnocellular preoptic nucleus; IPSP, inhibitory postsynaptic potential; LY, Lucifer Yellow; entorhinal area; Magnocellular neuron; Rat; Rodentia; Central nervous system; Electrophysiology; Projection; Hypothalamus; Anatomy; Vertebrata; Mammalia; Olfactory pathway; Entorhinal cortex; Piriform cortex; Preoptic nucleus; Olfactory bulb; Postsynaptic potential; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(96)00566-0

The magnocellular preoptic nucleus of the rat supplies centrifugal input to the olfactory bulb as well as projecting to other olfactory-related areas. The extent to which the piriform and entorhinal cortices can influence the activity of magnocellular preoptic neurons and hence that of the olfactory bulb were examined using intracellular
in vivo recording. Stable recordings were obtained in 58 neurons impaled in the magnocellular preoptic nucleus. Antidromic responses occurred on stimulating olfactory bulb (15), piriform cortex (14), or entorhinal area (eight). Monosynaptic excitation was evoked by piriform (27 of 37 tested) and entorhinal cortex (15 of 32 tested) stimulation with polysynaptic inhibition occurring in seven and five neurons, respectively. Polysynaptic as well as antidromic excitation by olfactory bulb stimulation occurred in four; a further 28 tested responded polysynaptically. No response to olfactory bulb stimulation was monosynaptic. In stable impalements, 29 neurons discharged spontaneously in the absence of applied current. Lucifer Yellow and Neurobiotin were used to label 16 cells. All but one had smooth dendrites with soma diameters ranging from 8 to 24
μm.
These results provide a framework in which magnocellular preoptic neurons can influence olfactory processing by direct action on the olfactory bulb, which action can be boosted by positive feedback from the bulb through the olfactory piriform and entorhinal cortices.