Effect of nitric oxide synthase inhibition on the manipulative behaviour of Sepia officinalis.

Nitric oxide (NO), produced by nitric oxide synthase (NOS) in brain tissue, is essential for a variety of kinds of learning in vertebrates. In invertebrates, there are clear examples of an association between NO signalling and olfaction, feeding behaviour and learning. The role of NO as a neurotransmitter in the manipulative behaviour of Sepia officinalis was tested. Manipulative behaviour requires extensive chemotactile sensory processing, fine motor control and probably motor learning processes. NADPH-diaphorase activity (a reliable histochemical marker for nitric oxide synthase) was found in sensory epithelia and in the axial nerve cord of the arms. NOS inhibitor injections (L-NAME) produced an increase in the latency of prey paralysis. By placing mechanical constraints on the base of the fifth periopods of the crab, we prevented the cuttlefish from injecting cephalotoxin and, thus, forced it to change injection sites. We showed that L-NAME pretreatment did not affect the flexibility of the manipulative behaviour. The implications of the involvement of NO in the acquisition of chemo-tactile information and in the programming of the motor skills of the manipulative behaviour is discussed.

The role of cholinergic networks of the anterior basal and inferior frontal lobes in the predatory behaviour of Sepia officinalis.

The predatory behaviour of the cuttlefish has been the subject of a few detailed studies and can be divided into several stages: prey detection, orientation, positioning, prey-seizing, prey-manipulation and ingestion. Nevertheless, the data about its control by the CNS remain fragmentary. By injecting a cholinergic agonist (nicotine) and antagonists (alpha-bungarotoxin, mecamylamine), the implication of cholinergic networks of the anterior basal and inferior frontal lobes in the control of predatory behaviour are demonstrated. Through these cholinergic networks, the anterior basal lobe takes an important part in the orientation and positioning. The inferior frontal lobe seems to play a role in the control of brachial manipulative and buccal mass activities. The implication of cholinergic networks of the anterior basal and inferior frontal lobes in the predatory behaviour and the pharmacology of nicotinic receptors are discussed.

Increase of learning abilities and maturation of the vertical lobe complex during postembryonic development in the cuttlefish, Sepia.

When shown prawns in a glass tube, cuttlefish quickly learn to inhibit their predatory behavior. By using a visual learning paradigm, we studied training and retention performances of cuttlefish aged from 8 to 90 days. We found an improvement in the acquisition of learning abilities during the first 2 months of life as well as an increase of 24-hr retention performance between 30 and 90 days of age. Using morphometric measurements of different lobes of the central nervous system, we correlated the emergence of these learning abilities with the postembryonic development of related nervous structures. Our results show that only the growth of the superior frontal and vertical lobes appears to be significantly correlated with the improvement of learning and long-term retention performances. Thus, as found in earlier data collected in Octopus, the vertical lobe complex of the cuttlefish seems to be involved in these learning processes.

Effects of learning on cytochrome oxidase activity in cuttlefish brain.

Using cytochrome oxidase (CO) histochemistry, the effects of instrumental conditioning in cuttlefish central nervous system were examined. The posterior superior frontal lobe showed an increase of CO labelling just after training, whereas the anterior superior frontal lobe exhibited a decrease of CO staining 24 h post-training. These findings provide the first metabolic evidence for the involvement of the superior frontal lobe in learning and memory processes in cuttlefish. It is concluded that CO histochemistry can be used to provide a functional mapping of learning-induced plasticity in cuttlefish brain.

Effect of aging on manipulative behavior in the cuttlefish, sepia.

The cuttlefish is an active predator that is able to catch crabs of a size that is large relative to its own. The capture is followed by a complex manipulative behavior leading to paralysis of the prey by injection of a cephalotoxin. This manipulative behavior is relatively stereotyped, and earlier research has shown that the cuttlefish concentrates its bite on the articular basi-ischiocoxopodite membrane of the crab's fifth pair of pereiopods. By placing mechanical constraints on the base of the fifth pereiopods, we were able to demonstrate that this manipulative behavior presents a marked degree of stereotypy but is not rigidly fixed. Substantial behavioral differences, however, were observed between subadult and senescent cuttlefish. The existence of a reduction in behavioral flexibility in the older animals in reaction to the constraints is discussed.

Evidence for a specific short-term memory in the cuttlefish, Sepia.

Cuttlefish quickly learn to inhibit their predatory motor pattern when shown prawns in a glass tube. The available literature suggests that cuttlefish show an excellent retention between 2 and 8 min, a recovery of the predatory responses around 20 min and good retention after 1 h of the training phase. These results have been considered as the product of two separate short- and long-term memory stores. In this study, we have investigated the fact that the retention seen after a brief delay of the training phase corresponds to a true effect of learning. We compared animals under three experimental conditions. In two, there was a unique training trial of different duration (5 or 20 min), a third group served as controls. Our results demonstrate that the control situation failed to reduce the level of attack; in contrast the short-term retention, obtained after a single learning trial, is related to a specific short-term memory process.

Time differences in the emergence of short- and long-term memory during post-embryonic development in the cuttlefish, Sepia.

When shown prawns in a glass tube, cuttlefish quickly learn to inhibit their predatory behaviour. The available literature suggests that cuttlefish show an excellent retention between 2 and 8 min, a recovery of the predatory responses around 20 min, and good retention after 1 h of the training phase. These results have been interpreted as the product of separate short- and long-term memory stores. The retention performance for cuttlefish that learned not to attack prey was studied during their post-embryonic development at intervals corresponding to the rate of short- (5 min) and long-term (60 min) memory storage definite in adult cuttlefish. Short-term memory appeared fully operational as early as 8 days of age, whereas the 60-min retention performance increased progressively between 15 and 60 days of age. Results suggest that during post-embryonic development, there is a time lag between the establishment of short- and long-term memory systems.

Postembryonic maturation of the vertical lobe complex and early development of predatory behavior in the cuttlefish (Sepia officinalis).

In two groups of newly hatched cuttlefish, from eggs incubated at different temperatures, the emergence of predatory pursuit was correlated with the development of some characteristics of the vertical lobe complex (namely, the development of the vertical and superior frontal lobes and the appearance of the vertical-subvertical lobe tracts) and with the state of resorption of the inner yolk sac. The temperature of egg incubation influences the appearance of postnatal pursuit behavior. Expression of this predatory behavioral characteristic is concomitant with the appearance of the vertical-subvertical lobe tracts. In contrast, the growth of the vertical and the superior frontal lobes relative to the growth of the supraesophageal mass and final yolk absorption are not correlated with the appearance of pursuit. To maintain a prey in the frontal visual field during predatory pursuit, short-term memory processes must be involved. Thus, the development of the vertical-subvertical lobe tracts, which is concomitant with the emergence of pursuit, appears essential in the maturation of these short-term memory processes.

NADPH-diaphorase in a cephalopod brain (Sepia): presence in an analogue of the cerebellum.

This paper presents the first evidence of the presence of NADPH-diaphorase (NO synthase) in a cephalopod brain. NADPH-diaphorase is selectively localized in the central nervous system of Sepia: only the neuropils of the spines of the peduncle and posterior anterior basal lobes exhibit an intense positive staining. Staining is completely absent from the cell bodies. When the structural analogies of the peduncle and anterior basal lobes are correlated with the cerebellum, these findings suggest that NO may be involved as a signal molecule in learned motor skills.

Behavioural and neurohistological changes in aging Sepia.

The life cycle of the cuttlefish in the English Channel is characterized by a succession of homogeneous population cohorts. These conditions provide an excellent opportunity for the study of aging in this cephalopod. In a first longitudinal study, we considered the oldest animals and compared their success rates at the first capture attempt. During the first weeks of the study, the results remained constant and then, during the weeks immediately preceding the natural death, a dramatic drop was observed. This deterioration may be due to defects of visuomotor coordination. In a second study, we used an associative learning protocol with negative reinforcement and the performances of young and old animals were compared. The most striking results showed that the performances of the oldest animals during the retention test were very mediocre. Such results suggest that the long-term memory process is affected. Finally, a modification of the Fink-Heimer silver stain enabled us to draw a map of spontaneous terminal degeneration in the central nervous system of the oldest animals. The structures which are characterized by the presence of multimodal inputs (the spine of the peduncle lobe and the basal lobes) present the most obvious signs of degeneration.

Learning performances and aging in cuttlefish (Sepia officinalis).

The use of an associative learning protocol with negative reinforcement allowed us to compare the performances of three groups of animals: young, middle-aged, and senescent. Statistical analysis of the results does not enable us to assert that a significant difference exists between the learning speeds of young and senescent animals. On the other hand however, the latter show poor scores in a retention test carried out 24 h after the learning session. These results suggest that the long-term memory processes are affected during the aging of these animals.

Manipulative motor activity of the cuttlefish Sepia Officinalis during prey-capture.

Following capture by the cuttlefish Sepia officinalis , crabs are manipulated by active movements of all eight arms to facilitate prey paralysis and ingestion. This manipulative behaviour is described for the first time. Prior to ingestion the prey is regularly held in a specific orientation, termed the "reference position", irrespective of the initial angle of attack. Prey capture is followed by an initial, very rapid manipulative phase, bringing the cephalo-thorax-abdomen junction of the crab to lie adjacent to the mouth of the cuttlefish. In this position the cuttlefish can inflict a wound, usually to the proximal joints of the hind pereiopod. The salivary toxins are probably injected into this wound provoking a rapid paralysis of the prey. A second manipulative phase orientates the crab into the "reference position". This phase involves complex coordinated movements of the arms that can, in some cases, rotate the crab by up to 180°. Suppression of visual input has little effect on this behaviour. Tactile input concerning the position and movements of the pereiopods would appear to play an important rôle in the execution of this manipulation. Sensorial control of this behaviour and the possible existence of muscular receptors capable of detecting movements are discussed.

The anterior basal lobe and control of prey-capture in the cuttlefish (Sepia officinalis).

The predatory behaviour of the cuttlefish comprises several stages: prey-detection, orientation, translation and prey-seizing. In this neuroethological study, lesions to the anterior basal lobe were made by an electrolytic method and the animals were allowed to attack their prey in an unrestricted way so that motor defects, functional recovery and the emergence of new adaptative behavioural strategies could be studied. Lesions to the central region of the anterior basal lobe suppress the orientating behaviour, thus only prey situated in the frontal visual field can be seized. Less extensive lesions in this region are associated with similar defects. Without head orientation, the cuttlefish still rotates with its fins. This rotation, however, is usually underestimated, tentacular ejection thus missing the prey. Dorsal lesions cause an underestimation of tentacular strike often associated with defects in maintaining ocular convergence. These results demonstrate the heterogenous function of the anterior basal lobe and its complex role in the control of predatory behaviour.

Motor and behavioural effects induced by putative neurotransmitter injection into the optic lobe of the cuttlefish, Sepia officinalis.

This paper presents a technique using local injections of different drugs directly into the optic lobe of Sepia. The cholinomimetic drugs induce a general decrease of the motricity, muscle tone, frequency of respiratory movements and decoloration of the animal. Dopamine and noradrenaline produce the same complex motor effects obtained by chronic electrical stimulation. Serotonin induces complex effects, particularly on the coloration. Some serotoninergic synapses could be implicated in the triggering of colour patterns.

Prey capture by the cuttlefish (Sepia officinalis L): An experimental study of two strategies.

This study shows that the size of the prey (Carcinus maenas ) relative to the predator (Sepia officinalis ) is of importance in the choice between two types of attack: either capture by ejection of the two extensible tentacles, or capture by jumping on the prey. Small crabs are preferentially captured by the first method and large crabs by the second. Other factors which may explain the observed variations, include previous experience of the predator and the behaviour of the prey.