Hippocampal-like circuitry in the pallium of an electric fish: Possible substrates for recursive pattern separation and completion.

Teleost fish are capable of complex behaviors, including social and spatial learning; lesion studies show that these abilities require dorsal telencephalon (pallium). The teleost telencephalon has subpallial and pallial components. The subpallium is well described and highly conserved.

Growth-associated Protein-43 (GAP-43) Expression In Ganglionic and Aganglionic Colon.

Abstract Objectives: Because of its specificity for nerve fibers of the enteric nervous system, calretinin is an effective adjunctive marker in the assessment for Hirchsprung disease. Growth associated protein (GAP-43) has been shown to be expressed in nerve fibers within the intestinal lamina propria. No prior report compares GAP-43 expression in ganglionic versus aganglionic intestine.

Expression of the cannabinoid CB1 receptor in the gymnotiform fish brain and its implications for the organization of the teleost pallium.

Cannabinoid CB1 receptors (CB1R) are widely distributed in the brains of many vertebrates, but whether their functions are conserved is unknown. The weakly electric fish, Apteronotus leptorhynchus (Apt), has been well studied for its brain structure, behavior, sensory processing, and learning and memory. It therefore offers an attractive model for comparative studies of CB1R functions.

Organization of the gymnotiform fish pallium in relation to learning and memory: III. Intrinsic connections.

The present article reports on the telencephalic connections of regions of the dorsal telencephalon of the weakly electric fish Apteronotus leptorhynchus and Gymnotus sp. that are involved in learning and memory: the lateral (DL), central (DC), and dorsal (DD) regions of the pallium and the intermediate region between DL and DC (Dx). We find that the main route of transmission consists of diencephalic (preglomerular complex; PG) glutamatergic input to DL; glutamatergic projections from DL to DC and Dx; and glutamatergic output from DC/Dx to di-, mes-, and rhombencephalic nuclei.

Organization of the gymnotiform fish pallium in relation to learning and memory: I. Cytoarchitectonics and cellular morphology.

The present article examines the anatomical organization of the dorsal telencephalon of two gymnotiform fish: Gymnotus sp. and Apteronotus leptorhynchus. These electric fish use elaborate electrical displays for agonistic and sexual communication.

Organization of the gymnotiform fish pallium in relation to learning and memory: II. Extrinsic connections.

This study describes the extrinsic connections of the dorsal telencephalon (pallium) of gymnotiform fish. We show that the afferents to the dorsolateral and dorsomedial pallial subdivisions of gymnotiform fish arise from the preglomerular complex. The preglomerular complex receives input from four clearly distinct regions: (1) descending input from the pallium itself (dorsomedial and dorsocentral subdivisions and nucleus taenia); (2) other diencephalic nuclei (centroposterior, glomerular, and anterior tuberal nuclei and nucleus of the posterior tuberculum); (3) mesencephalic sensory structures (optic tectum, dorsal and ventral torus semicircularis); and (4) basal forebrain, preoptic area, and hypothalamic nuclei.

Organization of the gymnotiform fish pallium in relation to learning and memory: IV. Expression of conserved transcription factors and implications for the evolution of dorsal telencephalon.

We have cloned the apteronotid homologs of FoxP2, Otx1, and FoxO3. There was, in the case of all three genes, good similarity between the apteronotid and human amino acid sequences: FoxP2, 78%; Otx1, 54%; FoxO3, 71%. The functional domains of these genes were conserved to a far greater extent, on average: FoxP2, 89%; Otx1, 76%; FoxO3, 82%.

Glomerular nucleus of the weakly electric fish, Gymnotus sp.: cytoarchitecture, histochemistry, and fiber connections--inisights from neuroanatomy to evolution and behavior.

The present study provides a detailed description of morphological and hodological aspects of the glomerular nucleus in the weakly electric fish Gymnotus sp., and explores the evolutionary and functional implications flowing from this analysis. The glomerular nucleus of Gymnotus shows numerous morphological similarities with the glomerular nucleus of percomorph fish, although cytoarchitectonically simpler.

Fiber connections of the diencephalic nucleus tuberis anterior in the weakly electric fish, Gymnotus cf. carapo: an in vivo tract-tracing study.

Transport of biotinylated dextran amine shows the spatial segregation of mechanosensory afferents in the nucleus tuberis anterior (TA) of a gymnotiform fish, Gymnotus cf. carapo. Only the intermediate subdivision of this nucleus receives projections from the lateral region of the ventral torus semicircularis (TSv), which represents the principal midbrain center for mechanosensory information processing, and from the ventral nucleus praeeminentialis, which receives collaterals of ascending second order mechanosensory fibers that emerge from the mechanosensory lateral line lobe.