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At least 523 records · Page 29Linked to original sources
PubMed2004

The "Yoking" of glutamatergic brain mechanisms involved in controlling brain neuronal excitability and psychosis to brain mechanisms involved in appetite regulation: a new hypothesis on the origin of psychosis.

The authors speculate that the human primate evolved psychosis generating brain mechanisms in the service of certain feeding behaviors (i.e., appetite, foraging) during the course of evolution. Furthermore, these "psychosis generating brain mechanisms" may have grown directly out of brain mechanisms servicing appetite, of which neuropeptide Y (NPY) played an important role. A case is made for an NPY contribution to the pathophysiology of psychosis. We hypothesize that the psychomimetic effects of NPY extend to supporting certain "psychomotor" functions that might have been useful for obtaining food resources in "stressful environments" (potentially food resource rich/predator-competitor dangerous). The "psychomotor" functions proposed include helping the evolving ancestral human primate overcome behavioral inhibitions and fears related to venturing into "stressful environments" (potentially food resource rich/predator-competitor dangerous) after their home ranges had been stripped of resources, by providing feelings of decreased anxiety (anxiolysis), infatigability, and, perhaps, even grandiose delusions of physical ability and supernatural supports. We further speculate that it is this NPY mechanism that in part becomes dysregulated in idiopathic psychotic disorders such as schizophrenia. The NPY connection with psychosis could theoretically account for the possible associations between weight changes and antipsychotic response (e.g. [Acta Psychiatr. Scand. 100 (1999) 3] reported by others and body mass index and cocaine-induced psychosis by our group (i.e. [Israel J. Psychiatr. (2004), in submission]).

Affective Disorders, Psychotic↗
PubMed1995

Systematic changes in gaping during the ontogeny of pecking in ring doves (Streptopelia risoria).

Food pecking in the ring dove is a skilled prehensile response that is similar to, but simpler than, many other prehensile responses. Previous work has shown that this response is initially poorly executed and requires experience for its accurate direction and coordination. The response involves two components: the thrusting of the bird's head toward food, and the opening and closure of the beak around food. Here, this second component, called gape, is followed through development with a precise measurement system. Four squabs moved through a similar sequence of three gape topographies, each of which is more efficient in picking up seed, during development. The present outcome, together with other work, argues for a substantial contribution of experience with pecking to the development of food pecking. We discuss the implications of these findings for understanding the ontogeny of motor control and for understanding how experience affects behavioral development.

Aging↗
PubMed1991

The effects of progesterone on sexual behavior in male green anole lizards (Anolis carolinensis).

It is well known that androgen-dependent sexual behaviors in male mammals and birds are inhibited by exogenous progesterone (P). However, recent research on male whiptail lizards (Cnemidophorus inornatus) indicates that P can stimulate sexual and copulatory behavior. We report here both antiandrogenic and synandrogenic actions of P on sexual behavior in males of another reptile, the green anole lizard (Anolis carolinensis). Earlier reports on birds and mammals are reviewed and discussed in relation to a possible physiological role of P in influencing sexual behavior in male vertebrates.

Animals↗
PubMed1982

A comparison of the effect of preoperative gentling on the mouse killing and reactivity induced by lesions of the lateral septum, the medial accumbens nucleus, and the medial hypothalamus.

Adult male rats were either gentled or not gentled 10 min each day for 5 days and then subjected to lesions of the lateral septum, the medial accumbens, the medial hypothalamus, or were given sham lesions. Mouse killing was tested in the living cage on Days 2, 7, and 14 postoperatively while reactivity to the experimenter was tested on Days 3, 8, and 15. The frequency of killing in the gentled groups was always significantly higher than that of the gentled sham-lesion controls, but the frequency of killing by the nongentled groups was seldom significantly higher than that of the nongentled sham-lesioned controls. Gentling caused a slight enhancement of killing in the lesioned animals and a slight attenuation of killing in the sham lesioned animals. Preoperative gentling attenuated reactivity to the experimenter in animals with lesions of the lateral septum but not in those with lesions of the medial accumbens nucleus or the medial hypothalamus. The observation that preoperative gentling tends to increase mouse killing confirms previous observations. The finding that preoperative gentling attenuates reactivity following septal but not medial accumbens or medial hypothalamic lesions suggests that these structures subserve different functions in the inhibitory modulation of defensive behavior.

Animals↗
PubMed1993

Sex differences in anxiety behavior in rats: role of gonadal hormones.

These experiments examined the role of gonadal hormones at both the organizational and activational time periods on sex differences in plus-maze behavior. In the first experiment, adult female Long-Evans rats were found to spend more time on the open arms of the plus maze than adult males, indicating less anxious behavior. In the second experiment, male and female subjects received a neonatal treatment (chemical castration with flutamide or tamoxifen, vehicle injection, or no injection) and a prepubertal treatment (gonadectomy, sham surgery, or no surgery). Adult females receiving either neonatal tamoxifen or prepubertal ovariectomy spent less time on the open arms than control females, but females who received both treatments were the most defeminized subjects. Males were not affected by the absence of gonadal hormones at either time period. These experiment indicate that female gonadal hormones play an important role both organizationally and activationally in plus-maze behavior. The role of the GABA receptor complex in mediating this effect is discussed. Knowledge of sex differences in plus-maze behavior may help to make this maze a more useful tool in investigating anxiety behavior in rats.

Animals↗
PubMed1998

Characteristics of basolateral amygdala neuronal firing on a spatial memory task involving differential reward.

Previous research has shown that spatial, movement, and reward information is integrated within the ventral striatum (VS). The present study examined the possible contribution of the basolateral nuclei of the amygdala (BLA) to this interaction by examining behavioral correlates of BLA neurons while rats performed multiple memory trials on an 8-arm radial maze. Alternate arms consistently held 1 of 2 different amounts of reward. Recorded cells were correlated with motion, auditory input, space, and reward acquisition. Reward-related units were found that anticipated reward encounter, that responded during reward consumption, and that differentiated between high and low reward magnitude. This is consistent with the hypothesis that BLA neurons may provide the VS with reward-related information that could then be integrated with spatial information to ultimately affect goal-directed behavior.

Amygdala↗
PubMed1996

Social learning in the golden hamster (Mesocricetus auratus).

This study investigates whether golden hamster (Mesocricetus auratus) pups can acquire a new behavior by interacting with an experienced adult conspecific. The behavior consisted of using teeth and forepaws to retrieve a piece of food dangling from a small chain. Instrumental learning techniques were used to train the demonstrators. Four groups of pups were exposed to different kinds of social experience. In the first group, the pups interacted with their skilled mother; in the second group, they did the same with their inexperienced mother; in the third group, they interacted with inexperienced littermates; and in the fourth group, the pups were tested individually. At the end of an acquisition period, the pups were tested individually to assess their performance. The results demonstrate that interacting with a skilled mother has a remarkable effect on the acquisition of a new feeding behavior by hamster pups.

Aging↗
PubMed2000

Maternal behavior, paternal behavior, and pup survival in CD-1 albino mice (Mus musculus) in three different housing conditions.

Parental behavior, food consumption, and pup development in litters of CD-1 albino mice (Mus musculus) with single mothers or paired mothers in 3 different housing conditions were compared. Fewer pups survived when parents were required to run in a wheel to obtain food, and these pups had lower weights than pups in the wheel-noncontingent and no-wheel groups. The presence of the male facilitated pup survival in the wheel-contingent group but had no effect on pup growth. Mice in the wheel-contingent group ran more revolutions than those in the wheel-noncontingent group and spent less time in parental care. In the wheel-contingent group, males spent more time running and ate less food than females, suggesting that males may indirectly facilitate pup development by providing food for the mother. The results suggest that the presence of the male increases pup care and may facilitate maternal behavior under appropriate environmental conditions.

Animals↗
PubMed2000

Solving a cooperation task without taking into account the partner's behavior: the case of capuchin monkeys (Cebus apella).

Four pairs of tufted capuchin monkeys (Cebus apella) were tested in a task requiring that both partners pull a handle simultaneously in order for both to be rewarded. The experimental design, an improved version of that of R. Chalmeau, E. Visalberghi, and A. Gallo (1997), aimed at assessing the extent to which a monkey that is pulling takes account of the behavior and spatial position of its partner, that is, whether the monkey understands what cooperation involves. Although all pairs succeeded, pulling was not affected by the partner's behavior, and it was affected only to a certain extent by the partner's spatial position. In addition, more experienced capuchins did not outperform naive individuals. The finding that capuchins were successful without understanding the role of the partner suggests that their cooperation is not cognitively grounded, as has been argued in descriptions of the hunting behavior of wild capuchins.

Animals↗
PubMed1993

Indirect inputs to ventral temporal cortex of monkey: the influence of unit activity of alerting auditory input, interhemispheric subcortical visual input, reward, and the behavioral response.

1. This study examined nonvisual and indirect inputs to 1,021 single units recorded in inferotemporal and parahippocampal cortex of behaving macaques. 2. To better isolate these influences, a fully split-brain, split-chiasm preparation was used. Extracellular single-unit activity was recorded while the ipsilateral eye was covered. During the recordings the monkeys worked on a visual discrimination task that consisted of a series of presentations of single images. 3. When the interval between presentations was varied randomly (usually between 4 and 15 s) about one-quarter of these cells responded to an alerting tone sounded 500 ms before the onset of the visual image. That this response is due to the warning value of the tone was shown by finding that an identical tone sounded at the end of each trial produced no response from these cells. Use of an exchange between pairs of light-emitting diodes as a warning signal (one turned on as the other was turned off, also 500 ms before the visual stimulus onset) produced a similar response in many units. This indicates a subcortical route for the alerting signal. In most cases, warning responses were inhibitory, often delayed with respect to the warning signal occurrence to more nearly match the image arrival time. 4. Surprisingly, and despite the monkeys' confirmed split-brain status, occasional cells (approximately 2%) showed a response from a visual presentation limited to the other hemisphere. Although this subcortical visual input was far weaker than direct visual input, it was nonetheless statistically reliable. Importantly, the indirect input was stimulus specific and could form the neural basis for a limited interhemispheric visual transfer of the sort seen in human split-brain patients. 5. Also rarely, cells showed activity time locked to the animal's behavioral response.

Afferent Pathways↗
PubMed1991

Effects of varying stimulus disparity and the reinforcer ratio in concurrent-schedule and signal-detection procedures.

The present study measured the effects of stimulus and reinforcer variations on pigeons' behavior in two different choice procedures. Two intensities of white light were presented as the stimuli on the main key in a switching-key concurrent schedule and as the sample stimuli in a signal-detection procedure. Under both procedures, the scheduled rate of reinforcement was varied across conditions to produce various ratios of obtained reinforcement. These ratios were obtained for seven pairs of light intensities. In the concurrent schedules, the effects of reinforcer-ratio variations were positively correlated with the physical disparity between the two light intensities. In the signal-detection procedure, changes in the reinforcer ratio produced greater effects on performance when stimulus disparity was very low or very high compared to those found at intermediate levels of stimulus disparity. This discrepancy creates a dilemma for existing behavioral models of signal-detection performance.

Animals↗
PubMed2001

Amygdala regulation of nucleus accumbens dopamine output is governed by the prefrontal cortex.

A dynamic interaction between the prefrontal cortex (PFC), amygdala, and nucleus accumbens (NAc) may be fundamental to regulation of goal-directed behavior by affective and cognitive processes. This study demonstrates that a mechanism for this triadic relationship is an inhibitory control by prefrontal cortex on accumbal dopamine release during amygdala activation. In freely moving rats, microstimulation of basolateral amygdala at intensities that produced mild behavioral activation produced an expected rapid increase in glutamate efflux in the prefrontal cortex and the nucleus accumbens shell region of the ventral striatum. However, during the stimulation, dopamine release increased only in the prefrontal cortex, not in the nucleus accumbens. An increase in accumbal dopamine release was observed during the stimulation if glutamate activation in the prefrontal cortex was inhibited at either presynaptic or postsynaptic levels. Some behaviors expressed during the stimulation were intensified in animals in which prefrontal cortex glutamate activation was blocked. In addition, these animals continued to express stimulus-induced behaviors after the termination of stimulation, whereas normal poststimulus behaviors such as ambulation and grooming were not displayed as frequently. Considering that dopamine neurotransmission in the nucleus accumbens is thought to play an integral role in goal-directed motor behavior, these findings suggest that the prefrontal cortex influences the behavioral impact of amygdala activation via a concomitant active suppression of accumbal dopamine release. Absence of this cortical influence appears to result in an aberrant pattern of behavioral expression in response to amygdala activation, including behavioral perseveration after stimulus termination.

Amygdala↗