Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Appetitive Behavior”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98Linked to original sources
PubMed1989

Medial versus lateral hyperstriatal lesions in pigeons: effects on autoshaping, non-matching-to-sample and spatial discrimination learning at short and long intertrial intervals.

Three experiments contrasted the effects of medial and lateral hyperstriatal lesions in pigeons. Expt. 1 found that both types of lesion obtained slower acquisition of autoshaping, compared to unoperated controls. No group differences in maintained rate of autoshaped responding were found. Expt. 2 found that lateral but not medial lesions disrupted choice performance in a non-matching-to-sample (NMTS) task, in which initial preference was for the correct stimulus; birds with lateral lesions responded more slowly to the sample stimulus than did birds with medial lesions. Expt. 3 found that medial but not lateral lesions disrupted both acquisition and reversal of a spatial discrimination at a long, but not at a short intertrial interval (ITI). Medial lesions damage primarily the hyperstriatum accessorium and lateral lesions, the hyperstriatum ventrale; but no significant correlations between the extent of damage to either of these structures and severity of behavioural disruption were obtained. Implications of these findings for theoretical accounts of hyperstriatal involvement in learning processes are discussed.

Animals↗
PubMed1989

Unit activity in the medial septum during differential appetitive conditioning.

Unit activity in the medial septal area of the rat was studied during pavlovian appetitive differential conditioning. The firing pattern of cells in the medial septum is that of suppression to presentation of the conditioned excitor and no significant increase to the presentation of the conditioned inhibitor. This pattern is discussed in the context of a comparison with the pattern found in the lateral septal area and assesses the significance of the motivational value of the stimuli.

Animals↗
PubMed1989

Olfaction directs skilled forelimb reaching in the rat.

Rats were trained to reach for food pellets, which varied in size from 20 to 300 mg, from one of 21 locations on a shelf located just outside a test cage. After a barrier was lifted, giving access to a food pellet, latency to contact the food was timed, number of reaches to contact the food were counted, the distance of each misplaced reach from the food was measured and the success or failure of each attempt was noted. Control rats walked along the front of the cage sniffing to locate the food. Once they located a food pellet, they inserted their nose between the bars of the cage, sniffed the food for one to three respiratory cycles, raised their snout slightly, and then inserted a forepaw to grasp the food. They seldom required more than three reaches to contact the food and on about half of all trials they were successful in grasping the food. They were more successful in grasping medium-sized food pellets. Performance was unchanged on all measures after vision was occluded with eye patches. Following olfactory bulb removal, however, the rats no longer sniffed to locate the food or sniffed the food prior to initiating a reach. Rather they systematically moved along the length of the cage inserting their snout between the bars at each possible food location and without sniffing reached for the food 'as if blind'. Latency, number of reaches to contact the food and the distance of misplaced reaches increased whereas success rate remained unchanged. Substantial additional impairments were not produced when the bulbectomized rats were given visual occlusion. The study demonstrates that rats locate food and direct reaching using olfaction. The results are discussed in terms of the sensory control of skilled limb use and their relevance to the evolution of the sensory guidance of limb use.

Animals↗
PubMed1989

The effects of fornix transection and combined fornix transection, mammillary body lesions and hippocampal ablations on object-pair association memory in the rhesus monkey.

Cynomolgus monkeys were tested on an associative memory task in which they had to remember object-object pairings. Eight animals (4 unoperated monkeys and 4 monkeys with lesions to components of the 'hippocampal-mammillary' circuit) were trained initially on a conditional object-pair association task that was similar to simple discrimination learning, but which involved presentation of object-pairs instead of single objects. Object-pairs were made up from 4 different objects, each with an identical copy. Animals had to learn which pairings of the 4 objects were rewarded (e.g. AB or CD) and which pairings were not (e.g. AC or BD). Objects appeared as a member of both rewarded and non-rewarded pairs. After several stages of training all monkeys reached a high level of performance making greater than 90% correct choices. In a performance test the monkeys had to discriminate between 3 single objects depending on their past associations with the other objects. Animals had to choose the two objects which in initial training were rewarded as an object pair. Monkeys with the 'hippocampal-mammillary' circuit lesions learned the initial object-pair discriminations at the same rate as control monkeys. In the performance test, however, monkeys with the 'hippocampal-mammillary' circuit lesions performed at chance levels, whereas the control monkeys performed significantly better. The results demonstrate a dissociation between the 'habit' and 'mediational' memory systems for ostensibly the same object-pair associations. They also indicate an important contribution of the 'hippocampal-mammillary' circuit in nonspatial association memory.

Animals↗
PubMed1997

Effects of telencephalic ablation on short-term memory and attention in goldfish.

Two hypotheses regarding the functions of the teleost telencephalon (short-term memory and nonspecific arousal hypotheses) were examined by using a Y-maze training paradigm. A delayed reinforcement method, which allowed the separation of choice process (a process in which choice responses are evoked) and reward process (a process in which choice responses are reinforced), showed that normal fish can acquire clear learned responses to choice stimuli under different stimulus conditions between the choice process and the reward process, while telencephalon-ablated fish showed greatly impaired learning performance. Neither normal nor telencephalon-ablated fish could acquire learned responses to choice stimuli under neutral stimulus conditions in the reward process with respect to choice stimuli in the choice process. These results suggest that the telencephalon facilitates extratelencephalic short-term memory function essential for memory retention of choice stimuli and evoked choice responses until reinforcement, and support the supplementary function of the telencephalon suggested previously [Ohnishi, K., Telencephalic function implicated in food-reinforced colour discrimination learning in the goldfish, Physiol. Behav., 46 (1989) 707-712 and Savage, G.E., Temporal factors in avoidance learning in normal and forebrainless goldfish (Carassius auratus), Nature, 218 (1968) 1168-1169]. In addition, it was shown that cue information in the reward process is very important for the fixation of short-term memory of choice stimuli and choice responses. Furthermore, telencephalon-ablated fish also showed clear visual aspect selection, as did normal fish, when they were reinforced to a visual compound stimulus containing heterogeneous aspects (pattern and colour). This result shows that the telencephalon-related arousal or attentional function is not critical for aspect selection in goldfish. It seems that visual aspect selection in goldfish is performed without paying telencephalon-related 'selective attention' to an aspect.

Animals↗
PubMed1998

Chronic L-deprenyl treatment alters brain monoamine levels and reduces impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder.

Effects of chronic L-deprenyl administration on hyperactive behaviour and brain monoamine levels were studied in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. SHR were hyperactive, impulsive and had impaired sustained attention when tested with a multiple 2-min fixed interval (FI) 5-min extinction (EXT) schedule of reinforcement. Even low, 0.25 mg/kg, doses of chronically-administered L-deprenyl reduced the impulsiveness (bursts of responses with short interresponse times) of SHR, without altering the general hyperactivity or the impaired sustained attention. The drug had no effect on WKY behaviour. The levels of noradrenaline (NA), dopamine (DA), serotonin (5-hydroxytryptamine, 5-HT) and their metabolites, measured in neostriatum, nucleus accumbens and frontal cortex, showed that L-deprenyl effectively inhibited monoamine oxidase (MAO) activity. These results suggest that impulsiveness is a behavioural component that may be operating independent of the other components, like hyperactivity and deficient sustained attention, and that can be reduced by chronic MAO-B inhibition with L-deprenyl in this strain of rats. The positive effect of L-deprenyl on impulsiveness is discussed as due either to normalization of an asymmetric dopaminergic activity in the nucleus accumbens, or to a restoration of normal DA function in the prefrontal cortex.

Animals↗
PubMed1997

Unilateral striatal lesions impair response execution on a lateralised choice reaction time task.

A novel lateralised reaction time task is described and used to evaluate the effects of D-amphetamine injections and unilateral dorso-striatal lesions in rats. The task involves a two-lever Skinner box adaptation of the nine-hole box visual choice reaction time task first developed by Carli et al. D-Amphetamine had a dose dependent effect on nearly all aspects of task performance. Low and the intermediate doses of D-amphetamine speeded reaction time and movement time, and abolished the delay-dependent pattern or responding in the task. The highest dose of amphetamine disrupted the animals' ability to perform reliably, the task contingencies. Unilateral lesions in the dorsal neostriatum resulted in an increase of error trials, produced a bias to respond towards the ipsilateral side, and decreased the accuracy of responding to contralateral stimuli. The overall mean reaction time to contralateral stimuli was not influenced by the lesions, but the movement time was increased selectively when responding to contralateral stimuli. The data suggest that striatal activation by amphetamine increases motor readiness, which can enhance reaction time performance at the cost of increased errors due to anticipation of cue presentation, in particular at long holding delays. Conversely, striatal lesions induce lateralised defects in executive, rather than sensory, processes, and impair the animals' ability to execute movement towards the contralateral side.

Animals↗
PubMed1999

A quantitative autoradiographic comparison of binding to glutamate receptor sub-types in hippocampus and forebrain regions of a food-storing and a non-food-storing bird.

In two species of birds, food-storing marsh tits, P. palustris, and non-storing blue tits, P. caeruleus, quantitative receptor autoradiography was used to localize NMDA (N-methyl-D-aspartate)-sensitive [3H]glutamate, [3H]MK801, and [3H]AMPA binding sites, in six regions of the forebrain: hippocampus and parahippocampus, hyperstriatum accessorium (vision) and ventrale (sensory integration), neostriatum (auditory), and lobus parolfactorius (basal ganglia). In both species high levels of labelling to both NMDA and AMPA receptors were observed throughout the forebrain. However, a marked difference in receptor labelling was apparent between the two species, with levels of binding to NMDA ion channel sites being significantly lower (20%) in both the hippocampus and parahippocampus, in food storers compared to non-food storers. The levels of binding to other forebrain regions were remarkably similar in the two species. No differences were seen in the binding to AMPA receptors in forebrain regions of either species.

Animals↗
PubMed1999

The role of the agranular insular cortex in working memory for food reward value and allocentric space in rats.

The present experiment examined the effects of quinolinic acid (125 mM) lesions of the agranular insular area on working memory for food reward value and working memory for spatial locations. In both tasks a go/no-go procedure was used. Working memory for food reward value was assessed using a delayed conditional discrimination in which either a 20% or 45% sugar content cereal was associated with a reinforcement and the other cereal was not. In the spatial locations task, rats were allowed to enter 12 arms in a radial maze for a food reinforcement. Of the 12 arm presentations, three or four arms were presented for a second time in a session which did not contain a reinforcement. The number of trials between the 1st and 2nd presentation of an arm ranged from 0 to 6 (lags). Working memory was assessed by the latency to enter an arm during the 2nd presentation. In the food reward value task, agranular insular lesions produced memory deficits in a delay-dependent manner. In contrast, agranular insular lesions did not impair working memory for spatial locations. These results add to accumulating evidence suggesting that different types of working memory are distributed across separate prefrontal subregions.

Animals↗
PubMed1999

Forebrain serotonin depletion facilitates the acquisition and performance of a conditional visual discrimination task in rats.

Three experiments examined the effects of depleting forebrain 5-hydroxytryptamine (5-HT) on the acquisition and performance of an operant conditional discrimination in the visual modality. In the first experiment, rats with 5-HT lesions induced by infusing the neurotoxin 5,7-dihydroxytryptamine intracerebroventricularly acquired the conditional visual discrimination more rapidly than the sham-operated controls. Following acquisition, a series of manipulations of the task parameters tested the effects of the lesion on cognitive, sensory and motivational aspects of performance. In experiment two, the performance of rats that had acquired the task to asymptote before receiving lesions was assessed. The performance of this second group of serotonin-lesioned rats was similar to that of the pre-acquisition lesioned group following all but one manipulation of the task parameters. When the rate of stimulus presentations was increased, rats with forebrain 5-HT depletions were protected from the disruptive effects on performance seen in the sham-operated controls. This latter finding was also observed in a third experiment, in which the infusion of the 5-HT1A receptor partial agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT), directly into the dorsal raphe nucleus improved the performance of unlesioned rats following an increase in the rate of stimulus presentations. The results are discussed in terms of the behavioural, neurochemical and neuroanatomical specificity of serotonin function in appetitive learning and the implications for general theories of the function of serotoninergic processes in cognition.

Animals↗
PubMed1999

The effect of experimental epilepsy induced by injection of tetanus toxin into the amygdala of the rat on eating behaviour and response to novelty.

A minute dose of tetanus toxin injected into the amygdala of rats produced an apparently reversible epileptiform syndrome similar to that previously described after injection of the toxin into the hippocampus. During the active epilepsy the toxin-injected rats occasionally exhibited 'paroxysmal eating' and also sometimes ran round in circles attempting to bite their own tails. When presented with a novel but palatable food (chocolate buttons or harvest crunch) the toxin-injected rats showed less neophobia than their controls--they ate sooner and ate more. This was found both during the active epilepsy and several weeks later when they had recovered. A similar effect of amygdala injections was found in a second experiment, in which the effect was compared with that of toxin injection in the hippocampus. These rats were tested also on the playground maze on their approach response to a neutral novel object (in a familiar environment in the context of seven familiar objects). The amygdala rats did not show any increase in their novelty response; thus their reduction in neophobia was specific to an appetitive behaviour. In contrast, the hippocampally-injected rats did not exhibit a novelty response in the playground maze, but showed normal neophobia to a new food.

Amygdala↗
PubMed1999

Effects of excitotoxic lesions of the basolateral amygdala on conditional discrimination learning with primary and conditioned reinforcement.

Rats with excitotoxic lesions of the basolateral amygdala (BLA) were not impaired in the acquisition of an appetitive visuospatial conditional discrimination between stimuli varying in temporal frequency that has previously been shown to be sensitive to the effects of lesions of the striatum and cingulate cortex. After asymptotic performance was attained, discrimination was reinforced according to a fixed ratio (FR) schedule under which n presentations of sucrose were provided following n correct responses; each correct response also being reinforced immediately by a light acting as a conditioned reinforcer. Under these conditions of reinforcement when FRn=5, BLA-lesioned rats initially showed transient impairments in several aspects of performance, but rapidly attained control levels over subsequent test sessions. No further impairments occurred when FRn=10/20. However, in various conditions of extinction, further differences in performance were revealed between the BLA-lesioned and control groups, notably a significantly enhanced resistance to extinction when both sucrose and conditioned reinforcement were omitted. The results are discussed in terms of limbic-striatal mechanisms in the control of discrimination learning and the possible role of the amygdala in the mediation of different aspects of conditioned reinforcement.

Amygdala↗
PubMed1999

Enhanced conditioned approach responses in transgenic mice with impaired glucocorticoid receptor function.

The long-term consequences of impaired glucocorticoid receptor (GR) function on reward-related learning were studied in transgenic mice with impaired GR function in a series of experiments taxing conditioned and unconditioned approach responses to stimuli predictive of food. There was a double-dissociation in that transgenic mice with impaired GR activity showed enhanced conditioned exploration in situations when stimuli predicted reward, while free-feeding food consumption over 24 h was reduced. Previous experiments have shown altered accumbens dopaminergic activity in these animals. In line with these findings, we observed an enhanced behavioural stimulation of transgenic mice following administration of d-amphetamine (2 mg/kg). This suggests that the increase in preparatory responses in transgenic mice may be mediated via an enhanced accumbens dopaminergic activity, possibly secondary to alterations in other brain systems.

Animals↗
PubMed2000

Previous exposure to amphetamine increases incentive to obtain the drug: long-lasting effects revealed by the progressive ratio schedule.

The present experiment tested whether previous exposure to amphetamine would enhance rats' predisposition to self-administer a high dose of the drug under fixed (FR) and progressive ratio (PR) schedules of reinforcement. Rats in different groups were given five injections of either amphetamine (1.5 mg/kg, i.p.) or saline (1.0 ml/kg, i.p.), one injection administered every third day and, starting 10 days later, given the opportunity to lever press for amphetamine (200 microg/kg/infusion, i.v.) on each of several 4 h sessions. When allowed to self-administer up to 10 infusions under first an FR-1 and then an FR-2 schedule, amphetamine and saline pre-exposed rats were indistinguishable and readily acquired the lever press response. However, when tested under the PR schedule of reinforcement, rats previously exposed to amphetamine achieved higher break points than saline pre-exposed rats across six consecutive PR sessions. This difference between groups was long lasting and durable. When compared to saline pre-exposed rats on three separate tests conducted 10, 14 and 21 days following the last PR session, rats pre-exposed to amphetamine also showed (i) greater nucleus accumbens dopamine reactivity to amphetamine (1.0 mg/kg, i.p.), (ii) higher break points when retested on the PR schedule, and (iii) a greater locomotor response to amphetamine (1.0 mg/kg, i.p.). On the last test, both groups showed higher levels of locomotion than no drug control animals that received amphetamine for the first time on this test. These findings suggest that previous exposure to amphetamine produces a long lasting enhancement in the incentive motivation animals will exhibit in their effort to obtain the drug. This enhancement appears to parallel sensitization of the drug's locomotor and nucleus accumbens dopamine activating effects. It may very well be exacerbated by continued exposure to self-administered amphetamine.

Amphetamine↗
PubMed1999

Atrial natriuretic factor inhibits norepinephrine biosynthesis and turnover in the rat hypothalamus.

We have previously reported that atrial natriuretic factor (ANF) increased neuronal norepinephrine (NE) uptake and reduced basal and evoked neuronal NE release. Changes in NE uptake and release are generally associated to modifications in the synthesis and/or turnover of the amine. On this basis, the aim of the present work was to study ANF effects in the rat hypothalamus on the following processes: endogenous content, utilization and turn-over of NE; tyrosine hydroxylase (TH) activity; cAMP and cGMP accumulation and phosphatidylinositol hydrolysis. Results showed that centrally applied ANF (100 ng/microl/min) increased the endogenous content of NE (45%) and diminished NE utilization. Ten nM ANF reduced the turnover of NE (53%). In addition, ANF (10 nM) inhibited basal and evoked (with 25 mM KCl) TH activity (30 and 64%, respectively). Cyclic GMP levels were increased by 10 nM ANF (100%). However, neither cAMP accumulation nor phosphatidylinositol breakdown were affected in the presence of 10 nM ANF. The results further support the role of ANF in the regulation of NE metabolism in the rat hypothalamus. ANF is likely to act as a negative putative neuromodulator inhibiting noradrenergic neurotransmission by signaling through the activation of guanylate cyclase. Thus, ANF may be involved in the regulation of several central as well as peripheral physiological processes such as cardiovascular function, electrolyte and fluid homeostasis, endocrine and neuroendocrine synthesis and secretion, behavior, thirst, appetite and anxiety that are mediated by central noradrenergic activity.

Animals↗
PubMed2000

Recovery of food-taking in cats after lesions of the corticospinal (complete) and rubrospinal (complete and incomplete) tracts.

The food-taking movement by which a cat grasps a morsel of food and brings it to the mouth is governed by interneurones in the forelimb segments (C6-Th1) and is normally controlled by the cortico- and rubrospinal tracts. It disappears reversibly when these tracts are transected in C5. The reappearance after some time is at least in part due to a reticulospinal take-over of the command. We have compared the recovery after total transection of both tracts with that after lesions giving subtotal transection of the rubrospinal tract but total transection of the corticospinal tract. With 4-6% of the rubrospinal fibres left, the recovery of food-taking was clearly faster than after total transection.

Animals↗
PubMed2000

Control of digits via C3-C4 propriospinal neurones in cats; recovery after lesions.

C3-C4 propriospinal neurones (C3-C4 PNs) transmit the command for forelimb target-reaching in cats, while the command for food-taking is mediated by interneurones in the forelimb segments. The ability of the C3-C4 PNs to control digits has now been reinvestigated with combined lesions in dorsal C5 (transecting the cortico- and rubrospinal tracts) and ventral C2 (transecting reticulospinal tracts) leaving the C3-C4 PNs in sole control of the forelimb. Components of food-taking like flexion in the proximal interphalangeal joints were found in half of the cats. Supination and terminal flexion of the metacarpophalangeal joints by which normal cats bring the morsel of food to the mouth were lacking in all cats.

Animals↗