Dorsal noradrenergic bundle and selective attention in the rat.

Tested the role for the dorsal noradrenergic bundle (DNB) in selective attention and stimulus filtering in 4 experiments with 138 male Wistar rats. The DNB was damaged by stereotaxically guided injection of 4 μg of the neurotoxin 6-hydroxydopamine (6-OHDA). The latent inhibition effect was blocked by 6-OHDA-induced depletion of forebrain noradrenaline, whereas nonreversal shift performance was better in noradrenaline-depleted Ss than controls. Data indicate that Ss with DNB lesions are impaired in ignoring irrelevant stimuli. In situations in which control Ss did not learn to ignore irrelevant stimuli, no lesion-induced difference was found. Thus, controls and DNB lesioned Ss learned equally about each of 2 dimensions of a multiple-redundant discrimination task. This was assessed both by interpolated trials with only 1 dimension present and by shifts in which only 1 of the previous 2 dimensions remained relevant. It is concluded that the DNB lesion does not increase stimulus sampling globally but that it impairs performance only in those cases in which normal rats learn to ignore irrelevant stimuli. (53 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lack of effects of lesions of the dorsal noradrenergic bundle on behavioral vigilance

The effects of 6-hydroxydopamine (6-OHDA)-induced lesions of the dorsal noradrenergic bundle (DNB) were assessed in animals trained in a task designed to measure sustained attention, or vigilance. Infusions of 6-OHDA reduced frontal cortical noradrenaline contents but did not significantly affect striatal and hypothalamic noradrenaline contents. The performance of lesioned animals did not differ significantly from sham-lesioned controls. The performance of both the lesioned and sham-lesioned animals was impaired by the presentation of a visual distractor and by a decrease in the probability for a signal. The results from this study largely coincide with the results from previous studies on the effects of noradrenergic lesions on various aspects of attention. In contrast to the attentional functions assessed in this experiment, the ability to detect and select stimuli that are associated with activation of sympathetic functions is hypothesized to be sensitive to the effects of DNB lesions.     

Effects of dorsal noradrenergic bundle lesions on recovery after sensorimotor cortex injury

Several lines of evidence suggest that the recovery of the ability of rats to traverse a narrow beam after unilateral injury to the sensorimotor cortex is noradrenergically mediated. We tested the hypotheses that the influence of norepinephrine on beam-walking recovery occurs, at least partially, through effects in the contralateral and/or ipsilateral cerebral cortex. Rats had either a selective left or right 6-hydroxydopamine lesion or sham lesion of the dorsal noradrenergic bundle (DNB) 2 weeks before suction-ablation or sham injury of the right sensorimotor cortex. The rats' abilities to perform the beam-walking task were measured over the 10 days following cortex surgery. DNB lesions did not affect the initial severity of the beam-walking deficit and had no effect on the performance of the task in rats with sham cortex injuries. Lesions of the contralateral but not ipsilateral DNB significantly impaired recovery. Further, in cortically lesioned rats with contralateral DNB lesions, norepinephrine content in the cerebral cortex opposite to the sensorimotor cortex lesion was significantly correlated with recovery. These data suggest that the effect of norepinephrine on recovery of beam-walking ability may be partially exerted in the cerebral cortex contralateral to the injury.     

Attenuation of self-stimulation from substantia nigra but not dorsal tegmental noradrenergic bundle by lesions of sulcal prefrontal cortex

Swallowed foreign bodies, fixed in the esophagus, are not uncommon in childhood. Their symptoms, complications, diagnosis and treatment are discussed. An expectant attitude is justified in regard to smaller fistulas and in big fistulas due to foreign bodies up to the remission of the localized inflammatory reaction. The present surgical methods are reviewed in the light of recent literature and a case study of a child cured by segmental resection of the trachea.     

Dissociable effects of lesions to the dorsal or ventral noradrenergic bundle on the acquisition, performance, and extinction of aversive conditioning.

In six experiments, we studied the effects of lesions to either the dorsal or ventral noradrenergic bundle on the acquisition and extinction of the conditioned emotional response (CER) as measured in a conditioned suppression paradigm. Infusions of the neurotoxin 6-hydroxy-dopamine (6-OHDA) into the trajectory of the dorsal noradrenergic ascending bundle (DNAB) impaired the acquisition of on-the-baseline and off-the-baseline conditioned suppression. The acquisition impairment for on-the-baseline conditioning was also shown to still be present when training did not commence until 8 weeks following central noradrenergic depletion. However, in rats previously trained on the CER, DNAB lesions did not affect performance. There was also a small resistance to extinction following on-, but not off-the-baseline conditioning. The acquisition impairment was shown not to be because of an altered sensitivity to the footshock. In contrast, infusions of 6-OHDA into the ventral noradrenergic ascending bundle (VNAB) had no effect upon the acquisition of the CER in an on-the-baseline procedure, but retarded its extinction to a much greater extent. The results here are discussed in terms of other acquisition deficits shown by rats with DNAB lesions and with reference to Gray's "anxiety" and Mason's "selective attention" theories of locus coeruleus function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual control of conditioned responding in rats with dorsal hippocampal lesions.

The control exerted by contextual cues over classically conditioned responding was assessed for rats with electrolytic lesions of the dorsal hippocampus and sham-operated controls. In 3 experiments the rats received initial training with 2 reinforced cues, each presented in its own distinctive context, followed by a nonreinforced test in which the cues were presented in the other context. Both control and operated subjects showed context specificity, as evidenced by less vigorous responding to these cues than to cues presented on test in their original contexts. The groups did not differ in their ability to learn an explicit discrimination in which a given cue was reinforced in one context and nonreinforced in a different context (although the groups did differ on a simple autoshaping task). It is concluded that a special role for the hippocampus in the contextual control of conditioned responding still remains to be demonstrated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of knife-cut lesions of the medial forebrain bundle in self-stimulating rats.

Unilateral frontal-plane knife-cut lesions were made in the anterior medial forebrain bundle ipsilateral to a lateral hypothalamic self-stimulation electrode. Behavioral effects of the knife cut on self-stimulation reward and operant performance capacity were measured via the reward summation function method. Knife cuts placed at the level of the anterior commissure were ineffective in altering reward or motor/performance capacity, whereas knife cuts just posterior in the caudal lateral preoptic area degraded reward and sometimes impaired motor/performance capacity. In a second experiment, knife cuts placed posterior to the ventral tegmental area were ineffective unless they intruded on the ventral tegmental area itself. Several small knife cuts placed just anterior to the ventral tegmental were effective in reducing self-stimulation reward. The results are discussed in terms of the anatomical substrate of lateral hypothalamic self-stimulation reward and as a first step in a larger mapping study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illness-induced context aversion learning in rats with lesions of the dorsal hippocampus

In 2 experiments, rats with electrolytic lesions of the dorsal hippocampus and sham-operated control subjects were given injections of lithium chloride after exposure to a distinctive context. This procedure establishes a context-illness association in intact subjects. In Experiment 1, the strength of the context aversion was assessed by measuring the subjects' willingness to consume a novel flavor in the context. It was found that lesioned subjects showed less suppression of consumption than controls. Experiment 2 tested the ability of the context to block subsequent flavor-aversion learning and revealed less effective blocking in lesioned rats. These results are consistent with the view that hippocampal lesions retard context conditioning; unlike previous work that has made use of conditioned freezing as the measure of context conditioning, the present results are not explicable in terms of lesion-induced changes in general activity.     

Preoperative differential housing and dorsal hippocampal lesions in rats.

The resemblance between the effects of social isolation and of hippocampal lesions (HCLs) in rats led to a study that investigated whether rats socially isolated at weaning rather than grouped counterparts show less behavioral change after sustaining dorsal HCLs when adults. Ss were 8 grouped male Lister rats with HCLs, 8 grouped male controls, 8 isolated male with HCLs, and 8 isolated controls. In socially reared Ss, HCLs produced increased ambulation and object contact in an open field, reduced passive avoidance in a runway task, and produced faster acquisition of active avoidance in a shuttlebox, but there were no such differences in isolation-reared Ss. Ambulation and object contact in isolates were intermediate to those of HCL Ss and intact group-housed Ss, and the behavior of isolates during passive and active avoidance training was generally similar to that of grouped Ss with HCLs. The introduction of a distractor during approach training in an alley reduced running speeds more in Ss with HCLs than in controls. The significant interactions between housing and lesion state suggest that neural pathways associated with the hippocampal formation may mediate some behavioral effects of differential housing. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radial-arm maze behavior by rats with dorsal hippocampal lesions: Effects of cuing.

In 4 experiments with 180 male Wistar and Long-Evans rats, Ss with bilateral dorsal hippocampal lesions were impaired when tested on standard (noncued) versions of the radial-arm maze, but other hippocampal groups performed almost as well as cortical and operated control groups when salient visual cues were added to each arm. Preoperative training on the noncued, but not the cued, maze interfered with the benefits of postoperatively cuing hippocampal groups. Control groups performed equally well under all cuing and training conditions. Procedures that eliminated response sequencing did not affect performance of hippocampal or control groups. Results are interpreted as reflecting hippocampal involvement in mediating spatial cues, but not necessarily along the lines predicted by cognitive map theory. It is suggested that deficits of animals with hippocampal lesions represent 1 manifestation of a general impairment in processing information. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Epigastric antinociception by cervical dorsal column lesions in rats

OBJECTIVE: The purpose was to determine the optimal treatment protocol for women with a cervical vaginal diagnosis of atypical squamous cells of undetermined significance. STUDY DESIGN: By means of decision analysis, 8 strategies were compared in terms of cost, life expectancy, cost-effectiveness, and the number of cancers and complications from treatment. Data were obtained from the medical literature and the University of Iowa Hospitals and Clinics. RESULTS: Compared with more aggressive strategies, such as those that use immediate colposcopy, strategies featuring repeated smears were less expensive and carried fewer complications but had lower life expectancies per patient and more cancers. The strategy of repeating a smear annually had a lower cost per patient than did the other strategies, ranging from $112 to $989, and had a similar discounted life expectancy to that of the strategy with the longest discounted life expectancy. CONCLUSIONS: In most clinical scenarios strategies that used repeated smears were the most cost-effective.     

Blocking can occur without losses in attention in rats with selective removal of hippocampal cholinergic input.

Prior studies showed that 192 IgG-saporin lesions of cholinergic input to the hippocampus disrupted reductions in processing of uninformative stimuli. In 2 experiments in this study, the performance of rats with these lesions was examined in blocking procedures. In both lesioned and normal rats, previous pairing of one conditioned stimulus (CS) with food blocked conditioning of a 2nd CS when a compound of both CSs was paired with food. However, in subsequent savings tests, lesioned rats showed faster learning than did normal rats when the blocked CS was established as a signal for either reinforcement or nonreinforcement. Thus, the reduced attention to the blocked CS found in normal but not lesioned rats was not essential for the occurrence of blocking. Although rats with selective removal of hippocampal cholinergic input may be unable to reduce attention to redundant stimuli, other mechanisms of stimulus selection remain available to them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hyperstriatal lesions and attention in the pigeon.

In two experiments, pigeons with bilateral lesions of the hyperstriatum were compared with unoperated control birds on tasks designed to test an attentional account of hyperstriatal function. In both experiments, hyperstriatal lesions disrupted reversal learning but did not influence the retardation of learning associated with either nonreinforced preexposure to the to-be-conditioned stimulus (Experiment 1) or prior nondifferential reinforcement to the to-be-discriminated stimuli (Experiment 2). There was, however, evidence of an impairment in both the acquisition and maintenance of autoshaped responding in lesioned birds, an impairment that may reflect a disruption of classical associations in hyperstriatal pigeons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure of seriatim dorsal hippocampal lesions to spare spatial reversal behavior in rats.

Notes that the assessment of unaided functional sparing following sequential lesions has usually involved either neocortically controlled learned behaviors or nonneocortically controlled unlearned behaviors. Typically, the learned behaviors are protected by the seriatim operative procedure but the unlearned behaviors are not. This pattern of results could be a function of either the involved behavior (learned vs. unlearned) or the brain area mediating the behavior (neocortical vs. nonneocortical). In an attempt to distinguish between these 2 possibilities, a hippocampally controlled learned response was used to assess the occurrence of unaided functional sparing following sequential, spaced lesions in 30 male hooded rats. Results give no indication that the learned response was spared by the seriatim operative procedure even when the Ss were provided interlesion remedial training. (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact spatial learning in both young and aged rats following selective removal of hippocampal cholinergic input.

Studies using the selective cholinergic immunotoxin 192 IgG-saporin have demonstrated that lesions of the cholinergic input to the hippocampus from the medial septum/vertical limb of the diagonal band (MS/VDB) do not disrupt spatial learning in the water maze in young rats. However, age-related deficits in spatial learning correlate with the integrity of cholinergic neurons in the MS/VDB, suggesting that these neurons may be more crucial for spatial learning in aged rats. To investigate this hypothesis directly, we selectively lesioned these neurons in aged rats that demonstrated relatively intact spatial learning in an initial screening as well as in a comparison set of young rats. Intact and lesioned rats of both ages rapidly acquired a new place discrimination in a different spatial environment. These results indicate that the cholinergic input to the hippocampus is not differentially involved in spatial learning in aged rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Probability matching in visual selective attention.

J. Jonides (see record 1981-22746-001) suggested a model to account for shifts of spatial attention in visual search tasks with less than 100% cue validity. This 2-stage probability matching model was subsequently tested by Jonides (see record 1984-08558-001). Reaction time (RT) distribution characteristics provided some support for the model. The present author reanalyzes Jonides's data (including that published in 1981). Analysis showed strong support for the probability matching hypothesis. It is concluded that probability matching is an important strategic characteristic of visual spatial attention. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related decrement in auditory selective attention.

Young (n?=?30), middle-aged (n?=?32), and old (n?=?28) adults repeated (shadowed) words presented to the left ear at 60 words per minute with and without distracter words presented to the other ear. Dichotic shadowing error rate increased with age. An attempt to eliminate the age effect by adjusting for age differences in monaural shadowing errors, fluid intelligence, and pure-tone hearing loss did not succeed. When the analyses were confined to Ss who made no monaural shadowing errors, dichotic shadowing errors still increased linearly with age. These results showed that there are selective-attention deficits in older adults that cannot be accounted for by the uncertainty of the target location. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deficient passive and one-way active avoidance acquisition following medial forebrain bundle lesions in rats.

In 3 experiments with 93 Long-Evans male hooded rats, cathodal electrolytic lesions of the medial forebrain bundle (MFB) at posterior hypothalamic levels produced a mild, transient hypodipsia and lowered jump thresholds to footshock. Lesions produced marked deficits in passive avoidance performance in a paradigm that paired discrete, linearly incrementing footshock intensities with contact of a water spout following 48 hrs of water deprivation. Injections of levo-dextro-5-hydroxytryptophan (75 mg g, ip), the immediate metabolic precursor of serotonin, had no effect on the passive avoidance performance of either experimental or operated control Ss. Lesions of the MFB also resulted in deficient acquisition in a 1-trial step-through passive avoidance paradigm not using motivation to drink and caused a severe acquisition deficit in a 1-way active avoidance task. Lesions of the septal nuclei produced lowered jump thresholds but did not affect acquisition in the 1st passive avoidance task. Results are interpreted as indicating a lesion-induced deficiency in fear learning, independent of the serotonergic functions of the MFB. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial forebrain bundle lesions: Specific loss of feeding to decreased glucose utilization in rats.

Found that bilateral destruction of the medial forebrain bundle in female Sherman rats eliminated feeding to decreased intracellular glucose utilization (glucoprivation). The deficit was specific. Feeding was enhanced by dietary dilution and reduced by dietary concentration. More was eaten in the cold and less in the heat. The Ss were not differentially sensitive to quinine adulteration. They returned to normal body weight following regimens of gavage or of restricted feeding. Moreover, they did not differ from normal Ss in drinking to various thirst stimuli. It is suggested that the glucoprivic mechanism makes but a minor contribution to the initiation of spontaneous feeding. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Capture of attention in selective frequency listening.

Four signal-detection experiments demonstrated robust stimulus-driven, or exogenous, attentional processes in selective frequency listening. Detection of just-above-threshold signal tones was consistently better when the signal matched the frequency of an uninformative cue tone, even with relatively long cue-signal delays (Experiment 1) or when as few as 1 in 8 signals were at the cued frequency (Experiment 2). Experiments 3 and 4 compared performance with informative and uninformative cues. The involvement of intentional, or endogenous, processes was found to only slightly increase the size of the cuing effect beyond that evident with solely exogenous processes, although the attention band, a measure of how narrowly attention is focused, was found to be wider when cues were informative. The implications for models of auditory attention are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)