Disrupted patterns of consummatory behavior in rats with fornix transections

The feeding and drinking behavior was examined in male rats with fornix transections and sham-operated control rats. Total food and water consumption was recorded but supplemented by a pattern analysis of feeding and drinking behavior. The behavior of the rats was continuously monitored during four hour morning and afternoon sessions under ad lib access and during a two hour session following adaptation to a restricted access feeding schedule. Rats with fornix transections were more active and exhibited increased frequencies of rearing, eating and drinking. The increased meal frequency in rats with fornix transections was accompanied by decreased meal durations and a reduction in the length of intermeal intervals. Total food and water consumption was unaffected by fornix transection as were the duration of sleep bouts and the frequencies of grooming, sleeping and carrying shavings. Fornix transections also reduced food carrying and food hoarding but only under conditions of restricted food access. The results suggest that fornix transection does not alter major homeostatic regulatory mechanisms nor does it alter the components of feeding and drinking behavior. Fornix transection alters, instead, the organization of microregulatory feeding and drinking patterns.     

Auditory abilities of speakers who persisted, or recovered, from stuttering

OBJECTIVE: The purpose of this study was to see whether participants who persist in their stutter have poorer sensitivity in a backward masking task compared to those participants who recover from their stutter. DESIGN: The auditory sensitivity of 30 children who stutter was tested on absolute threshold, simultaneous masking, backward masking with a broadband and with a notched noise masker. The participants had been seen and diagnosed as stuttering at least 1 year before their 12th birthday. The participants were assessed again at age 12 plus to establish whether their stutter had persisted or recovered. Persistence or recovery was based on participant's, parent's and researcher's assessment and Riley's [Riley, G. D. (1994). Stuttering severity instrument for children and adults (3rd ed.). Austin, TX: Pro-Ed.] Stuttering Severity Instrument-3. Based on this assessment, 12 speakers had persisted and 18 had recovered from stuttering. RESULTS: Thresholds differed significantly between persistent and recovered groups for the broadband backward-masked stimulus (thresholds being higher for the persistent group). CONCLUSIONS: Backward masking performance at teenage is one factor that distinguishes speakers who persist in their stutter from those who recover. Education objectives: Readers of this article should: (1) explain why auditory factors have been implicated in stuttering; (2) summarise the work that has examined whether peripheral, and/or central, hearing are problems in stuttering; (3) explain how the hearing ability of persistent and recovered stutterers may differ; (4) discuss how hearing disorders have been implicated in other language disorders.     

Withdrawal from cocaine self-administration produces long-lasting deficits in orbitofrontal-dependent reversal learning in rats

Drug addicts make poor decisions. These decision-making deficits have been modeled in addicts and laboratory animals using reversal-learning tasks. However, persistent reversal-learning impairments have been shown in rats and monkeys only after noncontingent cocaine injections. Current thinking holds that to represent the human condition effectively, animal models of addiction must utilize self-administration procedures in which drug is earned contingently; thus, it remains unclear whether reversal-learning deficits caused by noncontingent cocaine exposure are relevant to addiction. To test whether reversal learning deficits are caused by contingent cocaine exposure, we trained rats to self-administer cocaine, assessed cue-induced cocaine seeking in extinction tests after 1 and 30 d of withdrawal, and then tested for reversal learning more than a month later. We found robust time-dependent increases in cue-induced cocaine seeking in the two extinction tests (incubation of craving) and severe reversal-learning impairments.     

Effects of transections to the vomeronasal nerves or to the main olfactory bulbs on the initiation and long-term retention of maternal behavior in primiparous rats.

While the onset of maternal behavior at parturition is mediated by hormones, the maintenance of maternal behavior during the first few postpartum weeks depends on experiences acquired while the dam interacts with pups (Rosenblatt, 1990). In fact, if female rats are permitted as little as 2 h or maternal experience within 36 h after Cesarean delivery, they exhibit heightened maternal behavior during maternal induction tests 10 days later; in contrast, dams separated from young at the time of Cesarean delivery and not permitted a maternal experience fail to respond maternally in tests 10 days later (Orpen & Fleming, 1987). In this study we investigated the role of chemosensory input through the vomeronasal and main olfactory systems in this maternal experience effect. Six groups of primiparous females were tested for maternal behavior to foster pups presented 9-10 days after Cesarean delivery: three groups were permitted to interact with pups for a 2-h period 36 h after Cesarean delivery; and three groups were separated from pups until testing and were given no maternal experience. Within each experience condition, one group sustained bilateral section of the vomeronasal nerves, one sustained bilateral coronal cuts through the midsection of the main olfactory bulbs, and one group sustained small medial olfactory bulb cuts. The results showed that animals sustaining vomeronasal or olfactory transections, regardless of experience condition, exhibited significantly reduced latencies to maternal behavior in maternal induction tests. However, these chemosensory disruptions did not prevent an additional facilitation of maternal behavior produced by a prior maternal experience.     

Sociopsychological profiles of students that leave the ingroup or engage in social competition

We present a study of the sociopsychological profiles of students who are disposed to engage in social competition on behalf of ingroup interests. Five predictors were selected: the advantageous or unfavourable context for ingroup interests, group identification, meritocracy, just-world beliefs, and social dominance orientation. It was found that those students who were prepared to invest personal resources on behalf of ingroup interests were characterized by a strong group identification and middle or low scores in the meritocracy and social dominance orientation. In contrast, students with the lowest disposition to social competition were defined by their low identification and/or middle-high scores in the meritocracy and social dominance orientation. Against our expectation, the manipulation of the favourable versus unfavourable situation of the ingroup did not have a significant influence. In order of their importance, the variables that showed stronger effects were group identification, followed by meritocracy, social dominance orientation, and world-just beliefs.     

Glucose attenuation of paradoxical sleep deficits in old rats.

Glucose administration enhances memory in several amnestic populations, including old humans and rodents. The present experiment demonstrates that glucose also enhances measures of sleep in old rats. Three-hour day-time sleep EEGs were assessed in 3- and 24-month-old rats. The animals received injections of saline or glucose (100, 500, and 1000 mg/kg) on different days in a counter-balanced order. At doses of 100 and 500 mg/kg, glucose augmented the duration of paradoxical sleep bouts and total paradoxical sleep time in old, but not young, rats. Within 2 weeks after the sleep tests, measures of several brain neurotransmitter functions were obtained. Glucose was more effective in enhancing paradoxical sleep in those individual aged rats with high levels of hippocampal choline acetyltransferase and occipital cortex serotonin concentrations than in aged rats with lower levels on these neurochemical measures. The findings suggest that glucose attenuates selective age-related sleep deficits in old rats. More generally, these results add to a growing body of evidence indicating that moderate doses of peripheral glucose can influence a variety of CNS measures.     

Equivalent spatial location memory deficits in rats with medial septum or hippocampal formation lesions and patients with dementia of the Alzheimer's type

College students, healthy elderly subjects, patients diagnosed with mild or moderate dementia of the Alzheimer's type, as well as rats with small or large lesions of the medial septum (MS), dorsal hippocampal formation (DHF) or nucleus basalis magnocellularis (NBM) were tested on an item memory task for a five- or six-item list of varying spatial locations. Equivalent patterns of item memory deficits as a function of serial order position were observed in rats with small or large MS or DHF lesions and patients with mild or moderate dementia of the Alzheimer's type. No deficits were found for NBM-lesioned rats. The results provide support for the possibility that rats with MS and DHF lesions mimic the mnemonic symptomatology of patients with Alzheimer's disease.     

Forgetting of trauma cues in adults reporting continuous or recovered memories of childhood sexual abuse

According to betrayal trauma theory, adult survivors of childhood sexual abuse (CSA) who were molested by their caretakers (e.g., a father) are especially likely to dissociate ("repress") their memories of abuse. Testing college students, some reporting CSA, DePrince and Freyd (2004) found that those scoring high on a dissociation questionnaire exhibited memory deficits for trauma words when they viewed these words under divided-attention conditions. Replicating DePrince and Freyd's procedure, we tested for memory deficits for trauma words relative to neutral words in adults reporting either continuous or recovered memories of CSA versus adults denying a history of CSA. A memory deficit for trauma words under divided attention was expected in the recovered-memory group. Results were inconsistent with this prediction, as all three groups exhibited better recall of trauma words than neutral words, irrespective of encoding conditions.     

Directed forgetting of trauma cues in adults reporting repressed or recovered memories of childhood sexual abuse

An item-cuing directed forgetting task was used to investigate whether women reporting repressed (n = 13) or recovered (n = 13) memories of childhood sexual abuse (CSA) exhibit an avoidant encoding style (and resultant impaired memory) for trauma cues relative to women reporting no CSA experience (n = 15). All participants viewed intermixed trauma (e.g., molested), positive (e.g., confident), and categorized neutral (e.g., mailbox) words on a computer screen and were instructed either to remember or to forget each word. The results provided no support for the hypothesis that people reporting either repressed or recovered memories of CSA are especially adept at forgetting words related to trauma. These groups recalled words they were instructed to remember more often than words they were instructed to forget regardless of whether they were trauma related.     

Retrieval inhibition of trauma-related words in women reporting repressed or recovered memories of childhood sexual abuse

Several authors have argued that survivors of childhood sexual abuse (CSA) who report to have repressed their traumatic memories are more skilled in forgetting emotional stimuli than survivors who have always remembered the abuse. The current experiment employed a list-wise directed forgetting task to investigate whether women reporting repressed (n = 16) or recovered (n = 23) memories of CSA are better at forgetting disturbing material, relative to women reporting having always remembered their abuse (n = 55) or reporting no history of abuse (n = 20). We found no support for the hypothesis that women reporting repressed or recovered memories of CSA are especially versed in inhibiting retrieval of trauma-related words. Additional analyses revealed that participants characterized by a repressive coping style did not display a superior retrieval inhibition mechanism for negative material.     

Reality monitoring in adults reporting repressed, recovered, or continuous memories of childhood sexual abuse

People who report either repressed or recovered memories of childhood sexual abuse (CSA) may have deficits in reality monitoring--the process whereby one discriminates memories of percepts from memories of images. Using signal detection methods, the authors found that adults reporting either repressed or recovered memories of CSA were less able to discriminate between words they had seen from words they had imagined seeing than were adults reporting either never having forgotten their CSA or adults reporting no history of CSA. Relative deficits in the ability to discriminate percepts from images (i.e., low d') were apparent on only some tests. The groups did not differ in their criterion--response bias--for affirming having seen versus imagined stimuli.