Promoter/repressor system of Lactobacillus plantarum phage og1e: characterization of the promoters pR49-pR-pL and overproduction of the cro-like protein cng in Escherichia coli

Previous studies have shown that extensive damage to the medial prefrontal cortex (mPFC) of rats causes reversal learning deficits. The mPFC of rats, however, consists of several subareas that are different from each other in both cytoarchitecture and neural connectivity, suggesting a functional dissociation among the mPFC subareas. In the present study, selective lesions of the mPFC of rats were made with a specially designed microknife whose intracranial placement could be controlled stereotaxically. Restricted lesions were made to each of the 3 parts of the mPFC: the anterior cingulate area (AC) (including the medial precentral area, PrCm), the prelimbic area (PL), and the infralimbic area (IL). One week after surgery, rats were trained in an aversively motivated visual discrimination task in a novel rotating T-maze. After reaching the acquisition criterion, rats were trained in a reversal task in the same maze. No difference was found in acquisition between control and mPFC lesioned rats. However, lesions of either the PL or the IL produced a marked deficit in the reversal task. This behavioral deficit was not found in rats with lesions of the AC. The results indicate that the mPFC of rats is not essential for discrimination learning, but that each of the 2 ventral subareas of the mPFC, PL, and IL, plays a critical role in reversal learning.     

The effect of catecholaminergic depletion within the prelimbic and infralimbic medial prefrontal cortex on recognition memory for recency, location, and objects.

There is good evidence that the medial prefrontal cortex (mPFC) is involved in different aspects of recognition memory. However, the mPFC is a heterogeneous structure, and the contribution of the prelimbic (PL) and infralimbic (IL) cortices to recognition memory has not been investigated. Similarly, the role of different neuromodulators within the mPFC in these processes is poorly understood. To this end, we tested animals with 6-hydroxydopamine (6-OHDA) lesions of the PL and IL mPFC on three tests of object recognition memory that required judgments about recency, object location, and object identity. In the recency task, lesions to both PL and IL severely impaired animals' ability to differentiate between old (earlier presented) and recently presented familiar objects. Relative to sham and PL animals, the IL lesion also disrupted performance on the object location task. However, both lesions left novel object recognition intact. These data confirm previous reports that the mPFC is not required for discriminations based on the relative familiarity of individual objects. However, these results demonstrate that catecholamines within the PL cortex are crucial for relative recency judgments and suggest a possible role for neural processing within the IL in the integration of information about object location. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effects of NMDA-induced retrohippocampal lesions on performance of four spatial memory tasks known to be sensitive to hippocampal damage in the rat

Four separate cohorts of rats were employed to examine the effects of cytotoxic retrohippocampal lesions in four spatial memory tasks which are known to be sensitive to direct hippocampal damage and/or fornix-fimbria lesions in the rat. Selective retrohippocampal lesions were made by means of multiple intracerebral infusions of NMDA centred on the entorhinal cortex bilaterally. Cell damage typically extended from the lateral entorhinal area to the distal ventral subiculum. Experiment 1 demonstrated that retrohippocampal lesions spared the acquisition of a reference memory task in the Morris water maze, in which the animals learned to escape from the water by swimming to a submerged platform in a fixed location. In the subsequent transfer test, when the escape platform was removed, rats with retrohippocampal lesions tended to spend less time searching in the appropriate quadrant compared to controls. Experiment 2 demonstrated that the lesions also spared the acquisition of a working memory version of the water maze task in which the location of the escape platform was varied between days. In experiment 3, both reference and working memory were assessed using an eight-arm radial maze in which the same four arms were constantly baited between trials. In the initial acquisition, reference memory but not working memory was affected by the lesions. During subsequent reversal learning in which previously baited arms were now no longer baited and vice versa, lesioned animals made significantly more reference memory errors as well as working memory errors. In experiment 4, spatial working memory was assessed in a delayed matching-to-position task conducted in a two-lever operant chamber. There was no evidence for any impairment in rats with retrohippocampal lesions in this task. The present study demonstrated that unlike direct hippocampal damage, retrohippocampal cell loss did not lead to a general impairment in spatial learning, implying that the integrity of the retrohippocampus and/or its interconnection with the hippocampal formation is not critical for normal hippocampal-dependent spatial learning and memory. This outcome is surprising for a number of current hippocampal theories, and suggests that other cortical as well as subcortical inputs to the hippocampus might be of more importance, and further raises the question regarding the functional significance of the retrohippocampal region.     

"Acquisition of a complex place task in rats with selective ibotenate lesions of hippocampal formation: Combined lesions of subiculum and entorthinal cortex versus hippocampus": Correction.

Reports an error in "Acquisition of a complex place task in rats with selective ibotenate lesions of hippocampal formation: Combined lesions of subiculum and entorhinal cortex versus hippocampus" by John-Paul Bouffard and Leonard E. Jarrard (Behavioral Neuroscience, 1988[Dec], Vol 102[6], 828-834). This article's corresponding plate appears on page 995. The information should read, "Plate A. Photomicrographs of horizontal, cresyl violet stained sections at dorsal, middle, and ventral levels of the brain for an unoperated control rat (left), an animal from the Subiculum + Entorhinal lesion group (middle), and a rat from the hippocampus group (right)." (The following abstract of the original article appeared in record 1989-28756-001.) The effects of isolating the hippocampus from its neocortical inputs and outputs by damaging the deep layers of entorhinal cortex and subiculum were compared with direct removal of the hippocampus using acquisition of a complex radial maze task. A series of eight problems (four out of eight arms being correct) were learned under either massed (45 s) or distributed (10 min) practice conditions, thus varying contextual information. Performance of rats with subiculum/entorhinal cortex lesions was similar to that of controls in all aspects of the radial maze task; whereas animals with hippocampal lesions were impaired on nearly all dependent measures. Although the effects of varying the intertrial interval were generally small, distributed practice did serve to facilitate the performance of hippocampal rats in terms of working memory. These findings are discussed as they related to recent theorizing in the area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contributions of the subregions of the medial prefrontal cortex to negative occasion setting.

The medial prefrontal cortex of rats has a role in many aspects of cognitive function, including forms of inhibitory learning. Recent studies suggest that there is heterogeneity in the contributions of the prelimbic (PL) and infralimbic (IL) regions of the medial prefrontal cortex to response inhibition. The present study tested the effects of separate neurotoxic lesions of the PL or IL on a serial feature negative discrimination task (negative occasion setting). Rats received training sessions consisting of 16 trials: on 4 trials in each session, a tone was presented and followed by food reward; on the other 12 trials the tone was preceded by a visual stimulus and not reinforced. The results indicate that PL but not IL is necessary for learning the discrimination. We then tested the effects of these lesions on rats that were first extensively trained in the task. Rats that had been trained for 30 days before receiving PL or IL lesions were still able to perform the task as well as controls after surgery. Thus, PL lesions disrupt acquisition but not performance of a serial feature negative discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Partial hippocampal kindling affects retention but not acquisition and place but not cue tasks on the radial arm maze

The performance of rats that were partially kindled in the hippocampus was assessed on an 8-arm radial arm maze with 4 baited arms. In rats first trained and then kindled, deficits were found on a place task in which rats reached the goal arms of the maze using salient extramaze spatial cues, but not on an intramaze cue task in which rats reached the goal arms using salient intramaze cues. Acquisition of a new place task on the maze was not different between kindled and control rats. In conclusion, partial hippocampal kindling disrupted the retention but not the acquisition of a spatial or place task; retention of a nonspatial cue task was not disrupted.     

Selective dysgranular retrosplenial cortex lesions in rats disrupt allocentric performance of the radial-arm maze task.

The present study provides the 1st report on the effects of selective lesions of the dysgranular portion of the retrosplenial cortex in rats. Excitotoxic lesions of the dysgranular area were sufficient to impair behavior in the radial-arm maze by biasing the strategy used to solve the task. In particular, rats with dysgranular retrosplenial lesions were less reliant on distal visual cues to control performance of a working memory task in the radial-arm maze. Instead, they were more reliant on using a motor turning strategy to solve the task. This change in strategy is consistent with anatomical data showing that the dysgranular region is the primary recipient of visual inputs to the rat retrosplenial cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition of a complex place task in rats with selective ibotenate lesions of hippocampal formation: Combined lesions of subiculum and entorhinal cortex versus hippocampus.

[Correction Notice: An erratum for this article was reported in Vol 103(1) of Behavioral Neuroscience (see record 2008-10623-001). This article's corresponding plate appears on page 995. The information should read, "Plate A. Photomicrographs of horizontal, cresyl violet stained sections at dorsal, middle, and ventral levels of the brain for an unoperated control rat (left), an animal from the Subiculum + Entorhinal lesion group (middle), and a rat from the hippocampus group (right)."] The effects of isolating the hippocampus from its neocortical inputs and outputs by damaging the deep layers of entorhinal cortex and subiculum were compared with direct removal of the hippocampus using acquisition of a complex radial maze task. A series of eight problems (four out of eight arms being correct) were learned under either massed (45 s) or distributed (10 min) practice conditions, thus varying contextual information. Performance of rats with subiculum/entorhinal cortex lesions was similar to that of controls in all aspects of the radial maze task; whereas animals with hippocampal lesions were impaired on nearly all dependent measures. Although the effects of varying the intertrial interval were generally small, distributed practice did serve to facilitate the performance of hippocampal rats in terms of working memory. These findings are discussed as they related to recent theorizing in the area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociations between medial prefrontal cortical subregions in the modulation of learning and action.

The medial prefrontal cortex (mPFC) has been implicated in various attentional functions. This experiment examined the involvement of mPFC subregions in the allocation of attention in learning and action as a function of the predictive accuracy of cues. Rats with dorsal (encompassing anterior cingulate, prelimbic, and infralimbic cortices) or ventral (encompassing mainly infralimbic and dorsopeduncular cortices and tenia tecta) mPFC lesions were trained in a multiple-choice discrimination task in which operant nosepoke responses to some visual cues were consistently (100%) reinforced (CRF) with food, whereas responses to other visual cues were partially (50%) reinforced (PRF). In challenge tests designed to assess attention in the control of action, responding was directed more to CRF cues than to PRF cues in sham and dorsal mPFC-lesioned rats, but ventral mPFC-lesioned rats showed similar levels of responding to both CRF and PRF cues. Nevertheless, when given a choice between simultaneously presented CRF and PRF cues in a cue competition test, all groups responded more to CRF cues. In a subsequent Pavlovian overshadowing phase designed to assess attention in the acquisition of new learning, previously trained CRF cues overshadowed conditioning to novel auditory cues more than did PRF cues in dorsal mPFC-lesioned rats, whereas the opposite pattern was observed in sham and ventral mPFC-lesioned rats. These results suggest a dissociation within the mPFC in the use of reinforcement prediction information to allocate attention for new learning and for the control of action. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Visual attention in the rat: A role for the prelimbic cortex and thalamic nuclei?

The behavioral effects of lesions of the prelimbic cortex (PL), mediodorsal nucleus of the thalamus (MD), and anterior thalamic nuclei (ANT) were investigated in 2 attentional tasks in rats: the 5-choice serial reaction time task and a vigilance task. Although there was no lesion effect on accuracy in the 5-choice task, PL lesions enhanced perseverative responding during baseline performance and when stimulus duration was reduced. In contrast, MD lesions increased premature responding during baseline performance and when the intertrial interval was varied unpredictably, In the vigilance paradigm, PL lesions also impaired rats' ability to detect the light signal at baseline and at the reduced stimulus duration. ANT lesions did not substantially disrupt performance. The results suggest that different aspects of attention may be attributable to the PL and the MD and that the mechanisms underlying inhibitory control of behavior may be attributable to functionally different thalamocortical circuits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial prefrontal cortex lesions in the female rat affect sexual and maternal behavior and their sequential organization.

Temporal sequences of sexual and maternal behaviors in female rats and their correlation with each other and with performance on a sensory-motor gating response inhibition task assessed by prepulse inhibition (PPI) were investigated following medial prefrontal cortex (mPFC) lesions. Following excitotoxic mPFC (n = 10) or sham (n = 9) lesions, sexual behaviors across the ovarian cycle were scored. After mating and parturition, maternal interactions were scored until pups reached postnatal Day 10. After resumption of the ovarian cycle, the female rats were tested for PPI. Compared with sham lesions, mPFC lesions impaired proceptive behaviors and some maternal behaviors (e.g., pup retrieval, pup licking) but did not affect others (e.g., nest building, pup mouthing). Lesions disrupted temporal sequences of solicitations (number of male orientations followed, within 4 s, by a level change) and pup retrievals (number of pup retrievals followed, within 5 s, by another retrieval). These sequential behavior patterns were significantly correlated with each other and with PPI. However, when PPI effects were partialled out, group differences were less strong, but persisted. This study demonstrated that mPFC manipulations affect actions rich in sequential structure in response to biologically relevant stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Foraging on the radial maze: The role of travel time, food accessibility, and the predictability of food location.

Reports on an experiment in which rats foraged in a 4-arm radial maze containing 4 feeders in each arm, with different percentages of baited feeders in each arm (0%, 25%, 50%, or 75%). The effects of three variables were examined: (1) Arm entrances were open or blocked to increase travel time between arms; (2) Feeders were uncovered or covered to decrease accessibility to food; (3) Food locations were randomly changed between sessions or remained fixed. Rats learned to discriminate between the 0% arm and arms containing food when food locations were fixed but not when food locations were random. Rats also learned the locations of baited feeders within arms with fixed food locations, but selectively visited baited feeders only if the feeders were covered. Comparisons of obtained data with computer simulations indicated that rats foraged near optimality. Patterns of foraging were best accounted for by a molecular maximizing model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance on spatial working memory tasks after dorsal or ventral hippocampal lesions and adjacent damage to the subiculum.

Rats with excitotoxic lesions of the dorsal or ventral hippocampus and control rats were trained on 2 spatial working memory tasks: the standard version of the radial maze with 8 baited arms and the nonmatching-to-place procedure in the T maze. Dorsal lesions produced deficits in both tasks, whereas ventral lesions did not affect learning in either of them. A volumetric analysis of subicular damage showed that dorsal hippocampal lesions caused a deficit in the nonmatching-to-place only when accompanied by damage to the dorsal subiculum; on the other hand, lesions to the dorsal hippocampus impaired performance in the radial-arm maze regardless of the extent of subicular damage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial learning and memory in the tortoise (Geochelone carbonaria).

A single tortoise (Geochelone carbonaria) was trained in an eight-arm radial maze, with the apparatus and general procedures modeled on those used to demonstrate spatial learning in rats. The tortoise learned to perform reliably above chance, preferentially choosing baited arms, rather than returning to arms previously visited on a trial. Test sessions that examined control by olfactory cues revealed that they did not affect performance. No systematic, stereotyped response patterns were evident. In spite of differences in brain structure, the tortoise showed spatial learning abilities comparable to those observed in mammals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prelimbic cortex specific lesions disrupt delayed-variable response tasks in the rat.

The role of the prelimbic cortex (PL) in rats was investigated with excitotoxic lesions. PL lesions altered the alternation scores in spontaneous and reinforced spatial delayed-alternation tasks. PL lesions induced a delay in conditioning under a temporal go/no-go alternation schedule but not under a continuous food-reinforcement schedule in a runway. PL lesions had no effect on the acquisition of a standard radial-arm-maze task nor on a fixed-goal location task but disrupted the acquisition of a variable-goal location task in a radial-arm maze. The present results indicate that PL lesions replicated most of the behavioral deficits obtained with larger prefrontal lesions. PL lesions disrupted the acquisition of delayed-variable response tasks while leaving unaffected fixed-response tasks. These results are discussed in relation with a working-memory, a response-selection, and an attentional hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Physostigmine, but not 3,4-diaminopyridine, improves radial maze performance in memory-impaired rats

The results of some studies suggest that 3,4-diaminopyridine (3,4-DAP), a drug that enhances the release of acetylcholine, may improve memory. The present study examined the ability of 3,4-DAP to reverse the memory impairment produced by scopolamine and the ability of 3,4-DAP and physostigmine to reverse the memory impairment produced by quinolinic acid lesions of the nucleus basalis magnocellularis (nbm) in rats. Mnemonic functioning was assessed with the use of a partially baited eight-arm radial maze. Entries into arms that were never baited were defined as reference memory errors; entries into baited arms from which the food already had been eaten were defined as working memory errors. In Experiment 1, 0.1 mg/kg scopolamine produced a significant increase in working and reference memory errors. Various doses of 3,4-DAP had no significant ameliorative effect on the mnemonic deficit. In Experiment 2, cholinergic function was impaired using a unilateral intra-nbm injection of quinolinic acid (120 nmol in 1.0 microliter). These lesions reduced the levels of the cholinergic marker, choline acetyltransferase, in the cortex by more than 40%. Results showed that the nbm lesion animals were significantly more impaired on the working than reference memory component of the task. Physostigmine (0.01, 0.05, 0.10, 0.20, 0.50 mg/kg) dose-dependently decreased the number of working but not reference memory errors. 3,4-DAP (10(-8), 10(-6), 10(-4), 10(-2), 10(0) mg/kg) had no reliable effect. It was concluded that physostigmine, but not 3,4-DAP, ameliorates memory impairments following decreases in cholinergic function.     

Differential contribution of dorsal and ventral medial prefrontal cortex to the acquisition and extinction of conditioned fear in rats.

The emotional reactivity of rats with lesions of the dorsal portion of medial prefrontal cortex (mPFC) was examined using a classical fear conditioning paradigm. Conditioned fear behavior (freezing responses) was measured during both the acquisition and extinction phases of the task. Lesions enhanced fear reactivity to both the conditioned stimulus (CS) and contextual stimuli during both phases, suggesting that dorsal mPFC lesions produce a general increase in fear reactivity in response to fear conditioning. M. A. Morgan, L. M. Romanski, and J. E. LeDoux (1993) found that lesions just ventral to the present lesions had no effect during acquisition of the same task and prolonged the fear response to the CS (but not the context) during extinction. Thus, both dorsal and ventral regions of mPFC are involved in the fear system, but each modulates different aspects of fear responsivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial guidance of choice behavior in the radial-arm maze.

In 6 experiments, the performance of male rats in a 12-arm radial maze was examined. The focus of study was the extent to which the spatial location of individual baited maze arms was determined before the rat was exposed to the extramaze visual cues corresponding to the arm, and thereby guided the rat toward the location of baited arms. Such spatial guidance of choice behavior implies a spatially organized cognitive representation of maze arms (i.e., a cognitive map). A higher level of spatial guidance was found when visual access to extramaze cues was restricted than when it was unrestricted. There was no evidence of a difference between the level of spatial guidance in the context of working memory performance and reference memory performance. Some evidence that intramaze cues contributed to microchoice guidance was found. However, spatial guidance, under at least some conditions, is best explained in terms of cognitive mapping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CHRONOMERGE: an application for the merging and display of multiple time-stamped data streams

Neonatal excitotoxic damage of the ventral hippocampus (VH) is a heuristic model of schizophrenia. We investigated whether: (1) neonatal damage of the medial prefrontal cortex (mPFC) has effects similar to the neonatal VH lesion; and (2) intrinsic mPFC neurons contribute to the abnormal behaviors associated with VH lesions. Neonatal rats were lesioned in the mPFC. In adulthood, they showed attenuated locomotion in response to novelty, amphetamine, and MK-801, and enhanced apomorphine-induced stereotypies as compared to controls. Striatal D1 and D2 receptor mRNAs were unaltered. Another group was lesioned in the VH and additionally in the mPFC in adulthood. Destroying mPFC neurons normalized hyperlocomotion to novelty and amphetamine of the neonatally VH lesioned rats. Thus, neonatal damage of the mPFC does not provide a heuristic model of schizophrenia-like phenomena, in contrast to analogous damage of the VH. However, mPFC intrinsic neurons that have developed in the context of abnormal hippocampal connectivity may be responsible for abnormal behaviors in the neonatally VH lesioned rats.     

Orangutan (Pongo pygmaeus abelii) spatial memory and behavior in a foraging task.

Orangutan (Pongo pygmaeus abelii) spatial memory was explored by using an arboreal foraging paradigm in a zoo environment. The experiment consisted of 4 tasks: walking maze, win-stay, food density, and competition. All 3 orangutans made very few revisits to previously depleted sites in the walking maze task. In the win-stay task, 2 orangutans were more accurate than chance at remembering locations of specific baited sites. Food density affected the behavior of 1 orangutan. Foraging with a competitor did not increase the orangutans' accuracy at recovering food from baited locations. The orangutans did not compete directly for access to the food sites but did avoid visiting sites depleted by a competitor. The orangutans' foraging patterns suggest that they minimized energy expended by reducing the distance traveled to retrieve food items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)