| Budget Amount *help |
¥13,800,000 (Direct Cost: ¥13,800,000)
Fiscal Year 2006: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2005: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2004: ¥8,900,000 (Direct Cost: ¥8,900,000)
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| Research Abstract |
This study was undertaken to reveal the neural mechanism for controlling the feeding behaviors mediated by taste sense in the sea catfish (Plotosus lineatus) and goatfish (Parupeneus).
In the first part, system of jaws, jaw muscles, and their innervation and function were studied in the catfish. Lower jaws are articulate with upper jaws at a ventral part of the quadrate, and the opening and closing of mouth is performed by moving only the lower jaws in a dorsoventral fixed axis. Muscles for mouth closing are identified 3 kinds of adductor mandibula while those for mouth opening are estimated levator arcus palatini, adductor operculi and adductor hyomandibulae. Trigeminal motor neurons innervate the 3 mandibular and hyomandibular addutors and facial motor neurons innery ate the others. The trigeminal and motor nuclei are subdivided into two subnuclei of which innervate different muscles in the periphery, indicating topographic, organization in the both nuclei.
In the second part, taste re
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flex pathways were examined through the trigeminal or facial motor nucleus. The trigeminal nucleus is shown to receive inputs from the facial lobe, neurons located reticular formation under the facial lobe, and third taste center in the inferior lobe as well as primary trigeminal neurons while he facial motor nucleus is shown to receive inputs from the posterior part of facial lobe, facial intermediate nucleus and the third taste center. Trigeminal and facial motor nuclei also send information each other through the interneurons which are located in the vicinity of each motor nucleus.
In the third part, a series of feeding behaviors were evidenced to achieve only through a taste sense alone by examining behaviors in normal and anosmia specimens. The catfish show a typical nocturnal locomotor activity which is controlled by an endogenous circadian oscillator.
In the fourth part, reflex pathways between the facial lobe and facial motor neurons as well as projections of the trigeminal, facial, glossopharyngeal nerves to the medulla were examined in the goatfish. The results complete the somatotopical maps in the entire primary taste center and suggests no contribution of trigeminal nerves to make a map. The facial motor neurons are suggested to receive taste input from the large neurons located in the deep layer of each tubercle of facial lobe, and inermediate facial neucleus. Less
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