摘要:

Evidence for ''coincidence detection'' or temporal summation mechanisms of temporal-pattern processing is presented for interaural-phase comparison in the barn owl''s brainstem and echo delay sensitivity in the auditory cortex of the echolocating bat Myotis lucifugus. In each system, temporal tuning is correlated with the synchronous arrival of excitatory inputs from different acoustic events. Input coincidence is achieved by differences in neural transmission delay that counterbalance acoustic time disparities. Neural transmission delays are spatially organized, thus producing a topographic representation of acoustic time disparity.

ISSN:0006-8977    

DOI:10.1159/000118696

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

A comparison of the coding and processing of temporally ordered information in electric fish and barn owls demonstrates a number of similar design features including different time and intensity channels and distinct morphological characteristics. Similar mechanisms, such as the presence of delay lines, underlie the sensitivity of both animals to small temporal disparities. Differences between the two systems may reflect the different substrates upon which evolution acted, and the different requirements of the two systems.

ISSN:0006-8977    

DOI:10.1159/000118697

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Certain species of anurans and electric fish detect amplitude modulations as a means of identifying conspecifics and foreign objects, respectively. This paper provides an account of the similarities between the electrosensory and auditory systems in terms of the mechanisms by which this temporal information is analyzed. Both animals employ a temporal filtering mechanism in this analysis. The transformation from a periodicity coding of amplitude modulations by the peripheral nervous system to a temporal-filter analysis in the central nervous system appears to be present in a number of different animals, ranging from crickets to cats. The possibility of a similar temporal filtering mechanism in humans and its role in perception are discussed.

ISSN:0006-8977    

DOI:10.1159/000118698

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

This essay addresses two questions: (1) What are the meanings of different kinds of brain maps? (2) Can the recognition of important communicative signals and other stimuli known to the system be adequately explained by an ensemble code? Several kinds and grades of brain maps are distinguished. Before we can properly state the meaning, especially of the higher forms of multiple and multifactor maps, we need to learn where they project. At the higher levels this is a labor-intensive task, requiring also ingenuity and ethological thinking to devise stimuli. The neuronal basis of recognition in those cases where behavior or perception is triggered in an either-or manner has chiefly been attributed to one or the other of two classes of models: (a) a large spatiotemporal configuration of many kinds of cells in which there is little convergence of input, and (b) a small set of nearly equivalent cells after successive convergences. The latter is known to exist but it is not clear how far it goes or for what classes of stimuli. The former is a more popular view but carries several burdens in required assumptions and is essentially not demonstrable or disprovable. I believe both exist and operate in sequence: specific ensembles are inputs to small sets of equivalent recognition units and specific arrays of different recognition units at higher and higher levels of abstraction may constitute the specific configurations for the most sophisticated recognitions. Our information base is pitifully small, especially in comparative physiology of higher integrative functions of the brain and in comparative behaviour.

ISSN:0006-8977    

DOI:10.1159/000118699

出版商:S. Karger AG    

年代:1986

数据来源: Karger