- Email: [email protected]
1. Introduction1
Symposium: Physiological Response and Stress1 1. I N T R O D U C T I O N DONALD POLIN2
Research and Development Laboratories, The Norwich Pharmacol Company, Norwich, New York 13815
H E physiology symposium at the Poultry Science Meeting in July 1968 evaded no issues. The participants brought forth the conflicts and the agreements, and these are aptly summarized in the reviews t h a t follow this introduction. Dr. van Tienhoven has covered in his review on " T h e Nervous System of Birds" the functions of (1) the hyperstriatum and (2) the hypothalamus in its regulation of feed and water intake and one area involving adrenal function. His concept on pineal function as an endocrine organ or as a biological clock should stir much interest and future research. I shudder to think of the obvious inferences t h a t could be drawn whenever avian physiologists report that the bird's brain has functional similarities to those occurring in man. However, I shall always take refuge in Dr. van Tienhoven's statement t h a t in birds a "cortex defined according to Cobb . . . is absent."
removes a structure t h a t controls the development of sites of antibody formation." T h e recent information t h a t Peyer's patches in the h u m a n m a y be analogous to the bursa in the fowl creates one more exciting reason for probing into the details of his review. Dr. Siegel has summarized succinctly and interestingly a very difficult and widely encompassing subject, "Environmental Stress and Physiological Compensating Mechanism in Fowl—Temperature and Respiratory Regulation." T h e broad aspects of his discussion as he interrelates neural, endocrine, behavioral, biochemical and cardiovascular mechanisms gives the reader an appreciation of research performed in this area. Direct and indirect heat loss are examined by Dr. Seigel, and his review on forces t h a t operate to control heat regulation has practical significance in poultry husbandry.
I n the "Immunological Control of the I m m u n e Response of the Fowl," b y Dr. Glick, we can relate the research of the avian physiologist to the problems confronting h u m a n medicine on the rejection phenomenon following transplantation or grafting. One can grasp the importance of these studies as Dr. Glick probes the details on the role of the immunological tissues and their biochemical control over antibody formation in birds. He summarizes this as follows: " I n splenectomy, one removes a major site of antibody formation . . . while in bursectomy, one
T h e major impacts these reviews have on the reader are not only what is stated, b u t also what is not stated. N o t stated are the problems to be answered concerning dehydration receptors, hemoglobin-oxygen dissociation curves under heat stress, blood-brain barrier as a protective mechanism in the humoral role of the brain, heat production from respiratory and cardiovascular activity added to the difficulty of dissipating heat against a declining temperature gradient between bird and environment during heat stress, the role of the catecholamines of the brain in the shivering mechanism, the humoral relationship in the immunological control of antibody formation and release, chemical regulators for food and water intake
1 A symposium held at the annual meeting of the Poultry Science Association, Texas A and M University, College Station, July 8-12, 1968. 2 Chairman of symposium and sessions.
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Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF AUCKLAND LIBRARY on May 2, 2015
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D . POLIN
and their role in neural transmission— and the list goes on. Symposia have their role in producing renewed interest in the subjects under review, and the scientists have performed their role well, as you will read. I wish to thank each of the participants
for their energetic support in making the symposium a success. I shall look forward to future physiology symposia at Poultry Science Meetings. From Science shall come Truth, From Truth shall come Science, From Faith shall come both.
A . VAN TlENHOVEN Department of Poultry Science, Cornell University, Ithaca, N. Y. 14850
Students of the avian nervous system are faced with somewhat of a dilemma because so little information is available on the anatomy and physiology of the avian system when it is compared with the available information for mammalian systems. Two strategies of attack are obvious. In the one strategy one basically "starts from scratch" and tries to obtain a bird's eye view of the problems or one may start with the knowledge of the mammalian system and one compares the similarities and differences in function between these classes and attempts to generalize from the data obtained. In this review an attempt is made to use the latter strategy. ANATOMY
Some of the major anatomical differences between many of the avian brains and many of the mammalian brains are: 1. In birds a cortex defined according to Cobb (1960) as "a peripherally placed coating (pallium) of cells arranged in layers" is absent. Haefelfinger (1957) and Stingelin (1958) have, however, considered the hyperstriatum to be analogous with the mammalian cortex. There is an area in the brain, the hippocampus, which borders the surface of the cerebral
hemisphere and shows layers of cells, but this structure is archicortex and not neocortex (Cobb, 1960). 2. The hyperstriatum is found in birds only. 3. The optic lobes are well developed in birds. 4. Generally, the olfactory system is poorly developed. Exceptions are: (a) those with well-developed olfactory bulbs—kiwi (Apteryx australis) (Craigie, 1930), procellariformes (Bang, 1965); (b) those with welldeveloped olfactory nerves—turkey vulture {Cathartes aura), Trinidad oil bird (Steatornis catipensis), Laysan albatros (Dromedea immutabilis), black-footed albatros (£>. nigripes) (Bang, 1960); (c) those with welldeveloped olfactory tubercles— honey guides {Indicator indicator; I. minor and / . variegatus) (Stager, 1967). In general, birds with small olfactory bulbs live in trees, and those with larger olfactory bulbs live in water, marshes, or on the ground (Cobb, 1960). Smell may be important for some species to locate their food, but the evidence is only observational (Stager, 1967). However, Michelsen (1959) using operant conditioning showed that pigeons discriminate be-
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF AUCKLAND LIBRARY on May 2, 2015
2. THE NERVOUS SYSTEM OF BIRDS: A REVIEW
Research and Development Laboratories, The Norwich Pharmacol Company, Norwich, New York 13815
H E physiology symposium at the Poultry Science Meeting in July 1968 evaded no issues. The participants brought forth the conflicts and the agreements, and these are aptly summarized in the reviews t h a t follow this introduction. Dr. van Tienhoven has covered in his review on " T h e Nervous System of Birds" the functions of (1) the hyperstriatum and (2) the hypothalamus in its regulation of feed and water intake and one area involving adrenal function. His concept on pineal function as an endocrine organ or as a biological clock should stir much interest and future research. I shudder to think of the obvious inferences t h a t could be drawn whenever avian physiologists report that the bird's brain has functional similarities to those occurring in man. However, I shall always take refuge in Dr. van Tienhoven's statement t h a t in birds a "cortex defined according to Cobb . . . is absent."
removes a structure t h a t controls the development of sites of antibody formation." T h e recent information t h a t Peyer's patches in the h u m a n m a y be analogous to the bursa in the fowl creates one more exciting reason for probing into the details of his review. Dr. Siegel has summarized succinctly and interestingly a very difficult and widely encompassing subject, "Environmental Stress and Physiological Compensating Mechanism in Fowl—Temperature and Respiratory Regulation." T h e broad aspects of his discussion as he interrelates neural, endocrine, behavioral, biochemical and cardiovascular mechanisms gives the reader an appreciation of research performed in this area. Direct and indirect heat loss are examined by Dr. Seigel, and his review on forces t h a t operate to control heat regulation has practical significance in poultry husbandry.
I n the "Immunological Control of the I m m u n e Response of the Fowl," b y Dr. Glick, we can relate the research of the avian physiologist to the problems confronting h u m a n medicine on the rejection phenomenon following transplantation or grafting. One can grasp the importance of these studies as Dr. Glick probes the details on the role of the immunological tissues and their biochemical control over antibody formation in birds. He summarizes this as follows: " I n splenectomy, one removes a major site of antibody formation . . . while in bursectomy, one
T h e major impacts these reviews have on the reader are not only what is stated, b u t also what is not stated. N o t stated are the problems to be answered concerning dehydration receptors, hemoglobin-oxygen dissociation curves under heat stress, blood-brain barrier as a protective mechanism in the humoral role of the brain, heat production from respiratory and cardiovascular activity added to the difficulty of dissipating heat against a declining temperature gradient between bird and environment during heat stress, the role of the catecholamines of the brain in the shivering mechanism, the humoral relationship in the immunological control of antibody formation and release, chemical regulators for food and water intake
1 A symposium held at the annual meeting of the Poultry Science Association, Texas A and M University, College Station, July 8-12, 1968. 2 Chairman of symposium and sessions.
9
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF AUCKLAND LIBRARY on May 2, 2015
T
10
D . POLIN
and their role in neural transmission— and the list goes on. Symposia have their role in producing renewed interest in the subjects under review, and the scientists have performed their role well, as you will read. I wish to thank each of the participants
for their energetic support in making the symposium a success. I shall look forward to future physiology symposia at Poultry Science Meetings. From Science shall come Truth, From Truth shall come Science, From Faith shall come both.
A . VAN TlENHOVEN Department of Poultry Science, Cornell University, Ithaca, N. Y. 14850
Students of the avian nervous system are faced with somewhat of a dilemma because so little information is available on the anatomy and physiology of the avian system when it is compared with the available information for mammalian systems. Two strategies of attack are obvious. In the one strategy one basically "starts from scratch" and tries to obtain a bird's eye view of the problems or one may start with the knowledge of the mammalian system and one compares the similarities and differences in function between these classes and attempts to generalize from the data obtained. In this review an attempt is made to use the latter strategy. ANATOMY
Some of the major anatomical differences between many of the avian brains and many of the mammalian brains are: 1. In birds a cortex defined according to Cobb (1960) as "a peripherally placed coating (pallium) of cells arranged in layers" is absent. Haefelfinger (1957) and Stingelin (1958) have, however, considered the hyperstriatum to be analogous with the mammalian cortex. There is an area in the brain, the hippocampus, which borders the surface of the cerebral
hemisphere and shows layers of cells, but this structure is archicortex and not neocortex (Cobb, 1960). 2. The hyperstriatum is found in birds only. 3. The optic lobes are well developed in birds. 4. Generally, the olfactory system is poorly developed. Exceptions are: (a) those with well-developed olfactory bulbs—kiwi (Apteryx australis) (Craigie, 1930), procellariformes (Bang, 1965); (b) those with welldeveloped olfactory nerves—turkey vulture {Cathartes aura), Trinidad oil bird (Steatornis catipensis), Laysan albatros (Dromedea immutabilis), black-footed albatros (£>. nigripes) (Bang, 1960); (c) those with welldeveloped olfactory tubercles— honey guides {Indicator indicator; I. minor and / . variegatus) (Stager, 1967). In general, birds with small olfactory bulbs live in trees, and those with larger olfactory bulbs live in water, marshes, or on the ground (Cobb, 1960). Smell may be important for some species to locate their food, but the evidence is only observational (Stager, 1967). However, Michelsen (1959) using operant conditioning showed that pigeons discriminate be-
Downloaded from http://ps.oxfordjournals.org/ at UNIVERSITY OF AUCKLAND LIBRARY on May 2, 2015
2. THE NERVOUS SYSTEM OF BIRDS: A REVIEW