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At least 145 records · Page 8Linked to original sources
PubMed1975

The subfrontal lobe and touch learning in the octopus.

Octopuses with the supraoesophageal lobes of the brain divided longitudinally can be taught to discriminate using the arms on either side. If there is no further lesion the two sides behave alike. Lesions limited to one side did not affect the performance of the contralateral, "control" side. Lesions made in the vertical (n=7) lobes led to a slight drop in the quality of performance in training to take a smooth sphere, in discrimination training (rough vs. smooth spheres) and in subsequent extinction and transfer tests. After removal of the median inferior frontal lobe (n = 10) there were somewhat greater effects in the same direction. Much larger effects followed interference with the subfrontal lobe (n = 20). Removal of parts from this always led to a marked loss of capacity for touch learning, broadly dependent on the amount of tissue removed. Removal of the whole of the subfrontal lobe (n = 6) produced animals that showed, at best, only very slight signs of learning. Such animals can adjust their overall level of response as a result of training but they seem incapable of adjusting response levels to two objects independently. These results are discussed in relation to the function of the subfrontal lobe as a memory store.

Animals↗
PubMed1976

On the structure and function of a neurohemal organ in the eye cavity of Eledone cirrosa (Cephalopoda).

The subpeduncualte lobe of the octopod brain produces a hormone that is released into the orbit. The hormone was extracted from Eledone cirrosa and assayed on the isolated perfused heart of the same species. It has a remarkable effect on amplitude, beat frequency and blood pressure; compared to equivalent extracts of posterior salivary gland it is about 70 times more effective. The substance is not a biogenic amine.

Animals↗
PubMed1980

Cobalt and horseradish peroxidase tracer studies in the stellate ganglion of octopus.

The connectivity of the stellate ganglion of Octopus was investigated using cobalt and horseradish peroxidase (HRP) tracers applied to severed preganglionic and postganglionic nerves. Centripetal cells, defined as cells in the ganglion which send their axons back toward the brain, were discovered by both methods. Application of HRP to the pallial (preganglionic) nerve labeled the preganglionic fibers which enter the ganglion and spread widely within the neuropil. Application of either tracer to a single stellar (postganglionic) nerve labeled motor neuron cell bodies spread over 1/4 to 1/3 of the ganglion. Since there are 25-40 such stellar nerves per ganglion, it may be inferred that there is only a limited topographic relationship between the location of motor neuron cell bodies in the stellate ganglion and the segment of mantle muscle which they innervate. The axon and many side branches of these motor neurons were also labeled. The smooth, diffuse form of HRP labeling produced in pre- and portganglionic axotomized neurons in Oct0pus is similar in appearance to that produced in damaged mammalian neurons.

Animals↗
PubMed1980

Retrograde intraaxonal transport of horseradish peroxidase by neurons in octopus.

While retrograde axonal transport is the basis of a widely used neuroanatomical method, it has been rigorously demonstrated in vivo only in a few vertebrate species and not yet in an invertebrate. Evidence is presented that motor neurons of the octopus stellate ganglion are capable of retrograde intraaxonal transport of horeseradish peroxidase. This demonstration shows that retrograde transport occurs in widely divergent groups of animals, and may be a general property of neurons.

Animals↗
PubMed1983

Biogenic amines in cephalopod retina.

Biochemical and ultrastructural studies by previous workers have suggested dopamine as a candidate neurotransmitter for the centrifugal neurons present in the cephalopod retina. We have examined the retina in 3 species of cephalopod mollusc and find strong green bands of glyoxylic acid-induced fluorescence in the synaptic plexus region. These results, together with data obtained from our Golgi impregnations, help to confirm previous speculations that the centrifugal neurons are dopaminergic.

Animals↗
PubMed1986

Organization of the motor neuron components of the pallial nerve in octopus.

Following horseradish peroxidase (HRP) and cobalt (CO2+) application to the pallial nerve of two species of octopus, neurons that control various aspects of mantle behaviors were located in several lobes of the three main regions of the central brain. In the subesophageal region, cells were labeled in the anterior chromatophore, posterior chromatophore, palliovisceral, pedal and vasomotor lobes; in the superior buccal lobe of the supraesophageal region; and in the magnocellular lobe of the periesophageal region. Localization of labeled cells in and around both the anterior and posterior chromatophore lobes suggests a modification of the idea that a single functional area is solely located in an anatomically defined brain lobe of a cephalopod.

Animals↗
PubMed1987

Localization of serotonin-immunoreactivity in the central nervous system of Octopus vulgaris by immunohistochemistry.

5-Hydroxytryptamine (5-HT, serotonin)-containing cells were localized in the central nervous system of Octopus vulgaris by use of the unlabelled peroxidase-antiperoxidase complex (PAP) immunohistochemical method employing highly specific antibodies to 5-HT present in paraformaldehyde-fixed tissue. Antibodies were raised in rabbits against an immunogen prepared by coupling 5-HT to bovine thyroglobulin (BTG) or to bovine serum albumin (BSA) with formaldehyde as the coupling reagent. The specificity of the immune reaction was studied by both absorption test and radioimmunoassay. The distribution of 5-HT immunoreactivity observed in octopus brain was essentially similar to that reported by other workers who used formaldehyde- or glyoxylic acid-induced fluorescence method. In addition, this immunohistochemical technique revealed 5-HT-containing perikarya in both the chromatophore and the palliovisceral lobes which were not detected by the previous fluorescence histochemical method. Thus, this immunocytochemical procedure appears to be a specific and very sensitive technique for the localization of 5-HT within the central nervous system of cephalopod Mollusca.

Animals↗
PubMed1990

Localization of serotonin immunoreactivity in cephalopod visual system.

The distribution of 5-HT-like immunoreactivity in paraformaldehyde-fixed sections of retina, optic nerve and the optic lobe of Octopus vulgaris was studied by both immunofluorescence and avidin-biotin complex (ABC) immunohistochemical methods utilizing polyclonal antibodies to 5-HT. Some immunoreactive serotonin-containing cells were demonstrated in the retinal plexus, optic nerve, the ciliary body and the lens-generating tissue by both methods. An analysis of dissected retina and optic nerve of Octopus vulgaris by high pressure liquid chromatography (HPLC) with an electrochemical detector (ECD) also showed the presence of 5-HT. In the optic lobe, three 5-HT-immunoreactive bands in the plexiform layer of the cortex were clearly immunostained, and in the medulla both the cell islands and the neuropil contained some cells immunostained by both fluorescein isothiocyanate (FITC) and ABC methods. This is the first report on the systemic immunocytochemical visualization of 5-HT-containing cells and/or fibers in the cephalopod visual system.

Animals↗
PubMed1993

Distribution of GABA-like immunoreactivity in the octopus brain.

This paper presents the first evidence that some neurons in the octopus CNS contain delta-amino butyric acid (GABA). Using conventional immunohistochemical methods with appropriate controls, we obtained positive staining with an antibody to GABA in fibres in the neuropil of many lobes of the brain of the northern octopus Eledone cirrhosa. In several lobes cell bodies were also stained. Staining was not uniformly distributed in the brain nor within a particular lobe: some regions stained strongly, others not at all. These findings suggest that GABA should be added to the already long list of putative neurotransmitters in the cephalopod CNS.

Animals↗
PubMed1994

The effect of L-glutamate on the afferent resting activity in the cephalopod statocyst.

The effects of bath application of L-glutamate and of excitatory amino acid agonists and antagonists on the resting activity of afferent crista fibers were studied in isolated preparations of the statocyst of the cuttlefish, Sepia officinalis. L-Glutamate (threshold 10(-5) M) and its agonists quisqualate and kainate (thresholds 10(-6) M) increased the resting activity in a dose-dependent manner. Glutamine (threshold 10(-5) M) was also excitatory, while D-glutamate had no effect. Also, no obvious excitatory effects were seen for NMDA and L-aspartate, nor was any antagonistic effect seen for the selective NMDA-receptor antagonist D-2-amino-5-phosphonovaleric acid (D-AP-5). The spider toxin Argiotoxin636 (threshold 10(-11) M), 2-amino-4-phosphonobutyric acid (AP-4), glutamic acid diethyl ester (GDEE), gamma-D-glutamylaminomethyl-sulfonic acid (GAMS), and kynurenic acid decreased the resting activity and effectively blocked or reversed the effect of L-glutamate and its non-NMDA agonists. Preliminary experiments with statocysts from the squid Sepioteuthis lessoniana and the octopod Octopus bimaculoides gave comparable results. All data show that in cephalopod statocysts L-glutamate, via non-NMDA receptors, has an excitatory effect on the activity of afferent fibers, an effect consistent with its possible function as a hair cell transmitter.

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