摘要:

The telencephalic hemispheres and the optic tectum of the turbot Scophthalmus maximus were analysed volumetrically during metamorphosis. Both brain regions develop an asymmetry coordinated chronologically with metamorphic events that produce asymmetry in the rest of the animal. Furthermore, the brain asymmetries are correlated with, and may be determined by, the side of origin of their primary afferent inputs, such that the more voluminous side of the brain receives these inputs from the zenithal side. After metamorphosis, the telencephalon remains asymmetric, whereas the optic tectum recovers its bilateral symmetry.

ISSN:0006-8977    

DOI:10.1159/000113819

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The location of principal and accessory motoneurons and principal interneurons of the nucleus abducens was determined in the Caspian terrapin (Mauremys caspica) by means of horseradish peroxidase histochemical tracing. Enzyme injections were made into the ipsilateral lateral rectus and retractor bulbi muscles and into the contralateral oculomotor nucleus. Labeled principal abducens motoneurons formed a cluster of cells in the rhombencephalon, under the IVth ventricle and adjacent to the medial longitudinal fascicle. The accessory abducens motoneurons were located more deeply in the rhombencephalon and more ventrolaterally than the principal motoneurons forming a compact aggregation of neurons. The principal interneurons of abducens nucleus were arranged as a cluster of cells under the floor of the IVth ventricle and more lateral than the principal motoneurons, with no intermingling.

ISSN:0006-8977    

DOI:10.1159/000113820

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The literature on fish hearing has increased significantly since our last critical review in 1973. The purpose of the current paper is to review the more recent literature and to identify those questions that need to be asked to develop a fuller understanding of the auditory capabilities and processing mechanisms of fishes. We conclude that while our understanding of fish hearing has increased substantially in the past years, there are still major gaps in what we know. In particular, the comparative functional literature is extremely limited, and we do not yet know whether different species, and particularly hearing specialists as compared to hearing nonspecialists, have fundamentally different auditory capabilities and mechanisms.

ISSN:0006-8977    

DOI:10.1159/000113821

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The literature on fish hearing has increased significantly since our last critical review in 1973. The purpose of the current paper is to review the more recent literature and to identify those questions that need to be asked to develop a fuller understanding of the auditory capabilities and processing mechanisms of fishes. We conclude that while our understanding of fish hearing has increased substantially in the past years, there are still major gaps in what we know. In particular, the comparative functional literature is extremely limited, and we do not yet know whether different species, and particularly hearing specialists as compared to hearing nonspecialists, have fundamentally different auditory capabilities and mechanisms.

ISSN:0006-8977    

DOI:10.1159/000316111

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The cerebellum has an important role in control and coordination of movements, but in some species, notably weakly electric fish of the family Mormyridae, anatomical, electrophysiological and behavioural evidence indicates that parts of cerebellar cortex are concerned with tracking movements of objects around the animal, rather than with controlling movements of the animal itself. The existence of such anomalies suggests that the cerebellum may not be exclusively, or even primarily, a structure for motor control. Evidence reviewed in this paper shows that the cerebellum is associated with sensory systems used for tracking movements of targets in the environment, as well as movements made by the animal itself, in all vertebrates, not just in a few isolated cases. The evidence indicates that the standard theory that the function of the cerebellum is control and coordination of movements only partially characterises cerebellar function. The cerebellum may be better characterised as a tracking system, with an important role in control and coordination of movements which arises because of an animal's need to track moving objects, to track its own movements, and to analyse the sensory consequences of movements in order to control movements. This theory not only predicts the known motor consequences of cerebellar dysfunction, it also predicts a specific kind of perceptual deficit caused by cerebellar dysfunction, namely an inability to accurately follow and predict trajectories of objects moving in the environment. A variety of behavioural and perceptual tasks in addition to motor control and movement tracking may require dynamical state estimation, and therefore may involve the cerebellum.

ISSN:0006-8977    

DOI:10.1159/000113822

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0006-8977    

DOI:10.1159/000113823

出版商:S. Karger AG    

年代:1993

数据来源: Karger