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Experimental Studies on hatching behavior in the Chick. III. The role of the midbrain and forebrain
Author(s) -
Oppenheim Ronald W.
Publication year - 1972
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901460405
Subject(s) - biology , hatching , forebrain , midbrain , anatomy , embryo , diencephalon , incubation , primordium , andrology , neuroscience , central nervous system , microbiology and biotechnology , ecology , medicine , biochemistry , gene
Various portions of the midbrain and forebrain of chick embryos were ablated by microsurgical techniques at early prefunctional stages of incubation (38–45 hours) in an attempt to assess the role of these parts of the nervous system in early embryonic motility and in later prehatching and hatching behavior. Embryos with the entire telencephalon and anterior diencephalon removed ( total FB ) exhibited no behavioral defects until about 20 days of incubation, at which time they were unable to initiate the final climax stage of hatching, in which the embryo normally cracks the shell around the circumference and emerges or hatches. On the other hand, embryos with no diencephalic damage and with sparing of parts of the cerebral hemispheres, were able to initiate the final climax stage, and actually manage to hatch ( partial FB ). Removal of only the dorsal part of the midbrain (primarily the primordia of the optic lobes) resulted in no behavioral deficits until after hatching. These embryos ( partial MB ) exhibited completely typical prehatching and hatching behavior. However, a complete gap in the midbrain region, separating the forebrain from the hindbrain, precluded all prehatching and hatching behavior. These embryos continued to exhibit behavior more characteristic of early (pre 16 day) embryonic stages and never managed to hatch. The possibility was discussed that the basic coordinated motor pattern utilized during prehatching and hatching stages (Type III activity) is organized in the hind‐ or mid brain area, but that in order for the final climax stage of hatching to be initiated and maintained, facilitation (or a more direct influence) from either (or both) the anterior diencephalon, or the caudal and basal parts of the telencephalon is needed.