摘要:

The concept of command is central to motor control theories and explanations for the initiation of behavior patterns. As currently conceived, command is a process of individual command neurons that receive sensory and other integrative information and trigger the expression of behavioral acts. We show that this concept is an inadequate framework in which to discover the neural mechanisms underlying the decision and execution processes that occur when an animal begins a behavioral act. We herein propose a new concept of command which is based on a suite of principles. In this concept, command is a dynamic system property intermediate to neurophysiological and behavioral contexts and independent of preconceived causal paradigms, methods, or structures. We visualize command within a neurobehavioral or neuroethological context. This provisional concept provides a way of thinking, and an approach for discovering the neural processes that underlie behavioral performance.

ISSN:0006-8977    

DOI:10.1159/000116580

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

In three breeds of domestic pigeons (fantails, homing pigeons, and strassers) the volumes of fresh, i.e. unfixed tissue of 14 brain structures were determined (telencephalon, diencephalon, nervus opticus, tectum, cerebellum, tegmentum and hyperstriatum accessorium, hyperstriatum ventrale, neostriatum, paleostriatum, hippocampus, septum, regio praepiriformis, bulbus olfactorius). Allometric comparisons that take into account differences in body weight and size were made among these three breeds. The tectum, hippocampus, paleostriatum and especially the neostriatum and olfactory bulb are remarkably larger in homing pigeons. These data are discussed in a functional context, in which the homing ability of homing pigeons is considered.

ISSN:0006-8977    

DOI:10.1159/000116581

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Recent neurophysiological studies of the granule cell (GC) layer in opossums and rats revealed extensive somatosensory projections to the cerebellar hemispheres and caudal vermis. These projections are organized as asomatotopic mosaics that are species-specific. To determine whether similar projections exist in a primate with a relatively small and simple cerebellum, we explored the GC layer of exposed folial crowns of anterior and posterior lobe cerebellar cortex of anesthetized giant galagos using juxtathreshold natural stimulation of mechanoreceptors and in-depth microelectrode micromapping techniques. We found (1) that stimulation of somatosensory mechanoreceptors by gentle touch, deep pressure, muscle stretch and joint movement revealed projections to the GC layer throughout the mediolateral extent of crus II, paramedian lobule, pyramis and rostral uvula (crus I was unresponsive); (2) that mosaic patterns of peripheral sources and submodality of projections were different for each lobule, and (3) that there were intraspecies and individual differences in subfoliation and in details of projections. Except for differences in mosaic pattern and relative size of different projections, these findings are similar to those in opossums and rats. These data suggest that somatosensory inputs to the cerebellum are not only functionally significant, but that they exist widely among mammals.

ISSN:0006-8977    

DOI:10.1159/000116582

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The jamming avoidance response (JAR) in young weakly electric fish, Eigenmannia, develops at the onset of a functional electrosensory phase-coding system, a neural pathway that is critical for the performance of the JAR. Size (measured in head to tail length) seems to be the best predictor of the onset of the JAR. A distinguishable JAR value (0.15 Hz or greater) develops in fish at a length of 12–15 mm, and its strength continues to increase with maturity until it approaches an adult value (8–20 Hz) at a length of about 45 mm. The JAR is not dependent upon social interactions, as it can be performed correctly upon first stimulation by animals raised in individual aquaria from the egg stage. Preliminary studies suggest that there are anatomical correlates to the development of the JAR behavior. As the JAR strengthens with age, there is a concomitant increase in the number of giant cells and a development of the commissural plexus in lamina 6 of the torus semicircularis. Giant cells play a pivotal role in the phase comparison circuit. Both phase and amplitude information play a role in the proper performance of the JAR, but the discrete nature of the phase comparison circuit allows the correlation between the development of the JAR and an essential part of the phase comparison circuit (lamina 6 of the torus) to be observed in Eigenmannia

ISSN:0006-8977    

DOI:10.1159/000116583

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The fiber connections of the accessory optic system (AOS) were investigated in a balistid fish, Navodon modestus (filefish), by means of horseradish peroxidase (HRP) and degeneration methods. Following injections of HRP into the corpus cerebelli, neurons in two retinal recipient nuclei, the area pretectalis pars dorsalis (APd) and area pretectalis pars ventralis (APv), were labeled retrogradely. In addition, a few neurons near the nucleus of the accessory optic tract (nAOT) were labeled. These neurons have dendrites extending into nAOT. Neurons in APv were also labeled by HRP injections into the oculomotor complex (nIII). However, no neurons were labeled in APd or nAOT. A few neurons in the lateral part of APv were labeled by HRP injections into the abducens nucleus (nVI). Three nuclei of the AOS, APd, APv and nAOT, were shown to receive tectal projections by the Fink-Heimer method. Thus, APv receives retinal and tectal projections, and in turn projects to corpus cerebelli, nIII and nVI. Specific efferent connections of the AOS in teleosts are discussed from phylogenetic aspects.

ISSN:0006-8977    

DOI:10.1159/000116584

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Neural control of heart rate (HR) was investigated in goldfish, Carassius auratus, using electrical stimulation of the brain. Three types of HR response were evoked by stimulation: HR decreases during stimulation (type I); HR increases during stimulation (type II), and HR decreases during stimulation, followed by increased rates at the offset (type III). Type I bradycardias were evoked by stimulation of the preoptic area and diencephalon, specifically in the ventral thalamus-dorsal hypothalamus transitional area, and the region dorsal and medial to the nucleus glomerulosus. Additional sites were located above crossing tectobulbar fibers in the midbrain and in basolateral medullary reticular areas, motor nucleus of the vagus and caudalmost vagal roots. Type II tachycardias were evoked by stimulation of sites in the dorsal telencephalon, inferior lobes of the hypothalamus and dorsomedial region of the vagal lobes. Type III rebound tachycardias were evoked from sites dorsal and medial to the nucleus glomerulosus and in the inferior lobe of the hypothalamus. The location of cardioactive sites in the brain in goldfish is comparable to that in other vertebrates; however, these cardiac responses may be mediated by faciliatory or inhibitory pathways to the vagal motor nuclei rather than sympathetic cardiac nerves.

ISSN:0006-8977    

DOI:10.1159/000116585

出版商:S. Karger AG    

年代:1988

数据来源: Karger