摘要:

Patterns of muscle activity (motor patterns) have generally been found to be strongly conserved during the evolution of aquatic feeding behavior within closely related groups of fishes and salamanders. We conducted a test of the generality of motor pattern conservation with a much broader phylogenetic scope than has been done previously. Activity patterns of three cranial muscles were quantified from electromyographic (EMG) recordings made during suction feeding in a salamander (Ambystoma mexicanum) and 4 widely divergent species of ray-finned fishes (Amia calva, Notopterus chitala, Micropterus salmoides and Lepomis macrochirus). General features of the motor pattern were the same in all species, but multivariate and univariate analyses of variance revealed highly significant differences among the 5 species in the average muscle activity pattern, indicating that the motor pattern has not been precisely conserved among these 5 taxa. Five of eight EMG variables that describe the intensity and timing of muscle activity differed among species. Only the intensity of activity of the adductor mandibulae appears to be a strongly conserved feature of the suction feeding motor pattern anamniotes. A discriminant function analysis of the 8 EMG variables successfully classified about two thirds of the feeding incidents as belonging to the correct species. In contrast to the results of previous studies of closely related taxa, we found that numerous quantitative differences exist among species, indicating that functionally significant details of suction feeding motor patterns have changed during evolution, whereas several general features of the pattern have been conserved.

ISSN:0006-8977    

DOI:10.1159/000116519

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

A nonuniform distribution of acetylcholinesterase (AChE) activity was identified in the granular layer of the cerebellum in rhesus monkeys. The distribution of darkly AChE-stained clumps in the granular layer was determined for each lobule of the vermis and the lateral cortex. The vermis contained a greater density of AChE reaction product than the lateral cortex. In the vermis, lobules IX and X had significantly the highest level of activity, followed by lobules VII and VIII, which were significantly higher than lobules II-VI. In the lateral cortex, the flocculus had the highest level of the AChE activity, followed by crus I and the dorsal paraflocculus, which had significantly higher levels than the remaining lobules. The high levels of AChE activity in the flocculonodular lobe and lobule IX may correspond to cholinergic mossy fiber transmission, but the high levels of AChE activity in other cerebellar regions probably involve noncholinergic functions. The significance of the nonuniform AChE distribution is not yet known, but may correspond to regional differences in neuronal or metabolic activity in the cerebellum that occur in conjunction with specific behaviors.

ISSN:0006-8977    

DOI:10.1159/000116520

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The dominant frequency of hippocampal rhythmic slow activity (RSA) is known to differ among species, even under similar experimental conditions. The cause of these species differences has not yet been identified. In this paper it is shown that RSA frequency is allometrically related to brain size for the 9 mammalian species for which data are available. It is further shown that the relationship between brain size and RSA frequency is similar to the relationship between brain size and specific brain metabolic rate. Based on these and other relationships, it is suggested that differences in the firing frequencies of the neuronal pacemakers underlying the generation of RSA reflect differences in specific brain metabolic rate, both within and among species.

ISSN:0006-8977    

DOI:10.1159/000116521

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Primate quadrupedalism has been reported to differ from that of typical mammals in a variety of features, the most discussed of which is footfall patterns. All prior explanations for this disparity have been based on morphological differences between primates and nonprimates. This paper questions the adequacy of the current and generally accepted explanation for these locomotor differences, which is based upon hypothesized differences in the location of the center of gravity. Additionally, it is suggested here that neurological factors rather than morphological ones primarily explain the unique attributes of primate quadrupedalism.

ISSN:0006-8977    

DOI:10.1159/000116522

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Members of the order Sirenia are unique among mammals in being the only totally aquatic herbivores. They display correspondingly specialized physiological, behavioral and anatomical features. There have been few reports concerning sirenian neuroanatomy, and most of these have consisted of gross anatomical observations. Our interest in Sirenia stems from the desire to understand neuroanatomical specializations in the context of behavior and the effort to elucidate trends in mammalian brain evolution. The architecture of frontal regions of cerebral cortex was investigated in several brains of the Florida manatee, Trichechus manatus latirostris. Through observation of sections stained for Nissl substance or myelinated fibers, several distinct cortical areas were identified on the basis of laminar organization. These range from areas with poorly defined laminae to those having 6 well-defined layers, some of which exhibit sublayers. Two cortical areas exhibit pronounced cell clusters in layer VI, and these stain positively for acetylcholinesterase and cytochrome oxidase. We hypothesize that these clusters may be involved in perioral tactile bristle function. Certain of our findings are consistent with previous observations in the literature on the brains of dugongs. On the basis of their lamination patterns, these frontal cortical areas appear to be organized into concentric zones of allocortex, mesocortex and isocortex.

ISSN:0006-8977    

DOI:10.1159/000116523

出版商:S. Karger AG    

年代:1989

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000116524

出版商:S. Karger AG    

年代:1989

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000116525

出版商:S. Karger AG    

年代:1989

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000116526

出版商:S. Karger AG    

年代:1989

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000116527

出版商:S. Karger AG    

年代:1989

数据来源: Karger