Haloperidol does not affect motivational processes in an operant runway model of food-seeking behavior

The present experiment examined the effects of dopamine receptor antagonism on subjects' motivation to seek food. Rats were trained to discriminate between 2 olfactory cues predicting either the presence (S+) or absence (S-) of food reinforcement in the goal box of a straight-arm runway. Rats learned to traverse the alley quickly when presented with the S+ and much more slowly when presented with the S-. Haloperidol pretreatment was unable to alter this pattern of behavior (i.e., rats still ran quickly when presented with the scent that predicted food availability). Thus, it seems that the same dopamine antagonist treatments that have been shown to disrupt food reinforcement do not prevent the food-seeking behavior produced by presentation of food-predictive cues.

Anatomy and ultrastructure of the sporophyte of Takakia ceratophylla (Bryophyta)

In this study, morphogenesis and structure of the sporophyte of Takakia ceratophylla are characterized beginning with the late embryo and culminating in the fully dehisced capsule. Information is presented on the development, ultrastructure, and anatomy of the three organographic regions of the sporophyte, namely capsule, seta, and foot. Diagnostic features that identify Takakia as a moss include the gradual elongation of seta, persistence of an apical calyptra, expansion of the capsule after cessation of seta elongation, existence of a columella, monoplastidic meiosis, spore ultrastructure (including a perine layer deposited late in spore wall (development), and the structure of the foot. Commonalities with the capsule of the Andreaeopsida include sporogenous tissue that overarchs a central columella, absence of stomata, and lack of a peristome and operculum. Peculiarities of the genus are seen in the internal structure of the capsule, the disintegration of the columella with spore maturation, and the dehiscence of the capsule along a single, spiralled, longitudinal suture line. Passive spore dispersal through longitudinal splitting of the capsule occurs in andreaeopsid mosses, liverworts, hornworts, and seedless vascular plants. The precise mechanism of dehiscence along a spiralled suture is unparalleled in extant archegoniates but finds counterparts in ancestral land plants such as the pteridophyte Tortilicaulis.

Reinstatement of drug-seeking behavior produced by heroin-predictive environmental stimuli

The current study examined whether stimuli predictive of heroin availability were capable of inducing a relapse of drug-seeking behavior in an operant runway task. Olfactory stimuli (orange and almond food extract) served as discriminative cues about the availability (S+) or unavailability (S-) of heroin reinforcement (a single 0.1 mg/kg IV infusion) in the goal box of a straight arm runway. Following discrimination training, the running response was extinguished in the absence of the olfactory cues. On a single trial, the discriminative stimuli were then tested for their ability to reinstate running behavior prior to presentation of the heroin reinforcer. Subjects presented with the S+ on test day took significantly less time to traverse the alley than they did on the final day of extinction, while those subjects presented with the S- on test day continued to run slowly. These results demonstrate, in an animal model of drug self-administration, that environmental discriminative cues can produce a relapse in drug seeking behavior following a period of abstinence. The response-reinstating properties of the S+ odor were unaltered by pretreatment with any of three doses of haloperidol (0.0, 0.15 or 0.3 mg/kg IP), suggesting that the motivating properties of heroin-predictive stimuli or cues remain intact during dopamine receptor antagonism.

Mild head injury and speed of information processing: a prospective study of professional rugby league players

The sensitivity of several short tests of speed of information processing to the effects of mild head injury in rugby league football was investigated. The measures used were the Symbol Digit Modalities Test, the Digit Symbol Substitution Test, and the Speed of Comprehension Test. Two studies were conducted, the first to examine the effect of practice, the second to determine sensitivity to cognitive impairment immediately following injury. The first study established alternate form equivalence and demonstrated that performance on the Speed of Comprehension and Digit Symbol Substitution tests improved with practice, whereas the Symbol Digit Modalities test remained stable. A second study of 10 players who subsequently sustained mild head injuries showed that measures of speed of information processing were sensitive to impairment in the postacute phase, whereas an untimed task of word recognition (Spot-the-Word) was not. Speed of Comprehension was more sensitive to postinjury impairment than either the Digit Symbol Substitution or Symbol Digit Modalities tests. A repeated baseline assessment before injury using the higher score to reflect a player's potential, allowed measurement of impaired performance on sensitive tests.

Nitrous-oxide use. II. Risks, compliance, and exposure levels among Nebraska dentists and dental assistants

This study measured nitrous oxide (N2O) exposure levels of 70 dentists and their dental assistants, and related these results to minutes of N2O use, compliance with N2O use guidelines, and risk of exposure. Dentists and dental assistants averaged, respectively, 97 and 59 parts per million (ppm) in N2O exposure, much higher than the recommended 25 to 50 ppm. Estimated peaks of exposure averaged 1,415 and 986 respectively for the two groups. Dentists exposure levels were significantly higher than those of dental assistants in both measures. Correlations revealed a significant link between compliance and estimated maximum exposure, and between minutes of use and 40-hour exposure readings. The variables most predictive of 40-hour N2O exposure were: minutes of use, frequency of use, number of operatories equipped, education of staff members on N2O health risks and exposure control, and operation of scavenging systems with the recommended liters/minute. This study established a feasible methodology for long-term, field-based epidemiological studies on N2O exposure, and identified some key variables related to 40-hour exposures and estimated maximum exposure.

Nitrous-oxide use. I. Risk of potential exposure and compliance among Nebraska dentists and dental assistants

Patterns of nitrous-oxide (N,O) use among Nebraska dentists and dental assistants are reported. More than 800 respondents answered questions relating to risk of N,O exposure and compliance with N,O standards in the dental office: 73 percent of these dental practices using N,O have a state-registration permit. Dentists and dental assistants (from registered and unregistered practices) reported risk of exposure differently. Important compliance issues emerged (the average compliance rate was 9 on a scale of 17). Most N,O users have scavenging systems, but they are not properly operated. Few dental practices test for leaks or conduct N,O-monitoring tests. By complying with the recommendations for N,O administration, dental-care workers can minimize their risk of exposure.

Addition of anticholinergic solution prolongs bronchodilator effect of beta 2 agonists in patients with chronic obstructive pulmonary disease

A randomized, double-blind placebo-controlled clinical trial was designed to assess the safety, efficacy, and duration of the bronchodilation resulting from the addition of 500 micrograms of ipratropium bromide (Atrovent; Boehringer Ingelheim, CT) inhalation solution to standard small volume nebulizer treatments with 2.5 mg albuterol inhalation solution. A total of 195 patients (63% men, average age 64 years) with > 10 pack-year smoking histories and stable, moderate-to- severe chronic obstructive pulmonary disease (COPD; forced expiratory volume in 1 second [FEV1] 1.02 liter, 38.8% predicted) from eight university-affiliated chest clinics in seven U.S. cities were enrolled into the study. Asthma, rhinitis, and eosinophilia were exclusions, as was daily use of > 10 mg of prednisone (or 20 mg on alternate days). There was a 2-week stabilization period during which the patients were instructed in the use of the small volume nebulizers, which they used three times daily with albuterol alone. They were asked to keep daily logs of peak flow rates, pulmonary symptoms, and additional medication usage. On their test day 1 the subjects came to the pulmonary function laboratory having been off theophylline for 24 hours and beta 2-agonists for 12 hours and performed a baseline spirometry. They then received their morning small volume nebulizer treatment of albuterol to which was added either 500 micrograms if ipratropium bromide or a saline placebo. Spirometry was repeated at 15, 30, and 60 minutes, and then hourly for 8 hours. Subjects then took home a 2-week supply of albuterol and test drug for thrice daily use in their small volume nebulizer. They were evaluated for pulmonary symptoms and adverse effects every 14 days. The 8-hour spirometry was repeated on test day 43 and finally on test day 85. Primary data evaluated were the peak increase in FEV1 and the area between the FEV1 baseline value and the 8-hour FEV1 curve. Similar calculations were made for forced vital capacity (FVC) and 25-75% forced expiratory flow (FEF25-75%). On test day 1 the peak increase in FEV1 for the ipratropium bromide + albuterol subjects was 26% greater than those on placebo + albuterol (p < 0.003). The area under the 8-hour FEV1 curve was 64% greater in those given ipratropium bromide on test day 1 (p < 0.0002). Similar increases were seen in FVC and FEF25-75%. The peak improvements in FEV1 and FVC with the addition of ipratropium bromide to albuterol were maintained on test days 43 and 85. Considering the safety and efficacy profiles of this combination, the data would suggest that ipratropium bromide inhalation solution should be considered first-line therapy for those patients with COPD requiring small volume nebulizer treatments.

Haloperidol differentially affects reinforcement and motivational processes in rats running an alley for intravenous heroin

The role of drug-paired environmental stimuli in opiate self-administration was investigated by exposing animals to discrete cues that were predictive of the availability or unavailability of heroin reinforcement. Rats were trained to traverse a straight arm runway for a reinforcement consisting of a single 0.1 mg/kg intravenous infusion of heroin delivered upon entrance to the goal box. On each trial, one of two discriminative olfactory stimuli (orange and almond) was used: one which signaled the availability of heroin in the goal box (S+), and one which signaled its absence (S-). The effect of dopamine (DA) receptor antagonism on reinforcement and motivational processes was investigated by pretreating subjects with 0.0, 0.15 or 0.30 mg/kg of the DA receptor antagonist drug, haloperidol. Haloperidol had no effect on operant runway performance (i.e. goal time) in any condition. However, 24 h later, on the first post-treatment trial, those haloperidol animals that received heroin in the goal box on the previous trial (i.e. the S+ condition) ran reliably more slowly than subjects that received vehicle on the previous S+ trial. These results suggest that haloperidol does not affect the motivational properties of stimuli which predict the availability of heroin, while it does diminish the reinforcing effects of actually receiving heroin.

Effects of closed-head injury on attentional processes: generality of Sternberg's additive factor method

The present study examined the generality of Shum, McFarland, Bain, and Humphreys' (1990) findings that closed-head injury (CHI) selectively impairs different processes of attention (operationalized in terms of stages of information processing) depending on the severity of, and the time since, injury. The procedure of Shum et al. was based on Sternberg's additive factor method (AFM), with the mode of information processing involved being a physical-directional matching of visual stimuli. The present study followed a similar procedure except that a name-matching task was used. This task was administered to 16 first-year psychology students and two groups of CHI patients (viz., severe short-term (SS) and severe long-term (SL)) with matched control groups. The results obtained replicated the study by Shum in that the SS group was found to be impaired on the identification and response-selection stages of information processing whereas the SL group was found to be impaired only on the response-selection stage. The present study confirms that the AFM is not limited to one specific mode of information process and strengthens the validity of the conclusions made by Shum et al. regarding the effects of CHI on attention.

Assessment of attention: relationship between psychological testing and information processing approaches

Examined the relationship between the psychological testing and information processing approaches in assessing attention. Eighty-seven subjects (57 females, 30 males) undertook eight psychological tests of attention and a visual-spatial reaction-time task. Using the cognitive-correlate method (Posner & McLeod, 1982), it was found that three components of attention (viz., visual-motor scanning, sustained selective processing, and visual/auditory spanning) derived from the psychological tests could be significantly predicted by specific, yet different, combinations of six indices of information processing (mean reaction time (RT), mean movement time (MT), feature extraction, identification, response selection, and motor adjustment): (a) mean RT and mean MT were found to be the most important indices for predicting performance on visual-motor scanning; (b) the motor-adjustment stage was found to be the most important index for predicting performance on sustained selective processing; (c) the response-selection stage was found to be the most important index for predicting performance on visual/auditory spanning. These relationships are important for supporting the construct-related validity of the psychological tests of attention and for extending the generality and applicability of the RT task.

Hemispheric differences in image generation and use in the haptic modality

Forty adults and 40 children, all right-handed, were presented with either of two series of six nonsense shapes to palpate: Those who were divided into sections by grid lines and thus provided categorical information or those who provided a whole shape and coordinate information that could be processed globally. Subjects were given an Input condition where they formed a mental representation of the shape while palpating the unseen tactual stimulus with either hand, followed by an Evaluation condition in which they attempted to solve the task by generating and using the previously stored image. Evaluation response times showed that the left hemisphere was significantly faster at generating images from categorically stored information. Neither hemisphere had an advantage when generating an image from globally stored information.

Peritoneal dialysis in the neonatal period: outcome data

Scant information exists on the prognosis of infants with renal failure who receive peritoneal dialysis in the first month of life. We reviewed the outcome of 23 such patients 1 year after the onset of renal failure. Diagnoses included acute tubular necrosis (11 infants), renal dysplasia (5), obstructive uropathy (4), polycystic kidney disease (1), renal vein thrombosis (1), and renal artery thrombosis (1). Seven of the eleven patients with acute tubular necrosis had had cardiac surgery. At 1 year, eight (35%) of the patients had died, six (26%) had a full recovery, seven (30%) were receiving long-term dialysis awaiting a transplant, and two (9%) had chronic renal failure. Effective dialysis, characterized by the reversal of metabolic disturbances or attainment of fluid balance, was accomplished in all patients. The mean duration of dialysis was 4.5 months (range, 0.1 to 12 months). The most common complications of dialysis were peritonitis and catheter exit site infection. Despite the provision of supplemental calories via nasogastric tube, the majority of patients receiving long-term dialysis showed impaired growth and mild developmental abnormalities. Peritoneal dialysis is an effective means of renal replacement therapy in the neonatal period; however, the morbidity and mortality rate for this population remains high.

Attentional deficits in head-injured children: an information processing analysis

Attentional problems of closed head-injured (CHI) children were examined using an information processing (IP) approach. Based on Sternberg's (1969) additive factor method (AFM), the study examined attentional processes in terms of four stages and their corresponding task variables. A visual-spatial choice reaction-time task was undertaken with two groups of CHI children (severe and mild to moderate) and corresponding matched control groups. Results indicated that for this task both the CHI and the normal children exhibited a similar mode of linear, sequential information processing. It was found that the severe group was impaired not only in terms of slowed motor execution but also in terms of response selection. This group showed no impairment on the feature extraction, stimulus identification, and motor adjustment stages of processing. No evidence of impairment on any of the stages was found for the mild group. The utility of the AFM and implications of these findings are discussed with reference to CHI children and to neuropsychological assessment and rehabilitation.

A simple dual-task study of laterality, sex-differences and handedness

Nine-hundred and eighty-one right-handed and 55 left-handed subjects were required to tap with a pen for 10 secs between targets 6 cm apart whilst either saying nothing, reciting a tongue-twister or saying la-la. The numbers of dots produced in 10 secs in each condition were analysed. The right-handed group demonstrated the usually found degradation in their right-hand performance whilst reciting the meaningful words, but showed a lesser effect when saying la-la. Their left-handed performance was essentially unaffected. Absolutely no evidence for the presence of a sex difference in lateralization of language was found. The much smaller sample of left-handed subjects presented a complex picture of no significant effects, whether they were the sole left-handers in their family, or had other left-handed close relations.

Effects of closed-head injury on attentional processes: an information-processing stage analysis

The present study, based on Sternberg's (1969) additive-factor method, examined attentional processes in terms of four information-processing stages (feature extraction, identification, response selection, and motor adjustment). Four task variables were used to operationally define the stages (signal quality, signal similarity, signal-response compatibility, and foreperiod uncertainty). In two studies, a visuo-spatial reaction-time task was undertaken by a group of university subjects (Experiment 1) and by three groups of closed-head-injured patients (severe short-term, severe long-term, and mild short-term) and their corresponding matched controls (Experiment 2). The results indicated that both patients and normals exhibited a similar mode of linear information processing. In addition, it was found that the severe short-term group was impaired on the response-selection stage and response selection stage; the severe long-term group was impaired only on the response-selection; and no evidence of impairment was found for the mild short-term patients. The implications of these findings with reference to the study of attentional processes in closed-head injured patients and to neuropsychological assessment and rehabilitation are discussed.

Tactile perceptual asymmetry: the influence of motor activity and imagery instructions

The purpose of this study was to examine the degree to which changes in muscular activity modify tactile perceptual asymmetries. In two experiments subjects were presented with a series of pairs of random shapes to the fingers of each hand. Their task was to detect the occurrence of a previously learnt target shape. Pressing on to the shape was the only movement allowed and other types of motor activity, particularly tracing movements, were not permitted. Across experimental conditions subjects were required to change the pressure and hence muscular effort used to press upon the shape. A left-hand advantage was found across all experimental conditions and its size did not change when subjects were required to press either firmly or lightly upon the shapes. This result was also found when subjects were required to apply uneven pressure between the hands. One-half of the subjects also performed the experimental conditions following instructions to use imagery. This produced an enhancement of right-hand performance on the task with a loss of the left-hand advantage. The results suggest that observed tactile perceptual asymmetries, while unaffected by changes in muscular effort, are easily overridden by higher-order cognitive and motor processes.

A dual-task study of sex differences in language reception and production

The notion that females may be less lateralized than males for language reception was tested using a variant of the dual-task technique with 20 normal right-handed subjects. A unimanual tapping task was paired with one language reception task, and two language production tasks (one purely cognitive and the other requiring both cognitive and vocal involvement). Performance was impaired in all treatment conditions, regardless of hand used. Most impairment was, however, found in right-hand performance during the vocal condition. No sex differences were found.

Lateralised dual-task performance: the effect of muscular-repositioning

In two experiments subjects performed tapping tasks requiring different degree of muscular repositioning while concurrently performing a speech task. In all concurrent speech conditions right-hand performance was disrupted more than left-hand performance, but the degree of this differential disruption did not alter as a function of the muscular repositioning requirements of the dual-tasks. It was concluded that rapid muscular repositioning does not appear to be the source of lateralised interference effects observed in concurrent task studies. However, it may be argued that some minimum level of repositioning is required, particularly if the differential effect reflects a lateralisation of "kind" rather than of "degree". This needs further research. One relevant factor proposed here which may alter the degree of lateralised effects is the degree of muscular effort required to perform each of the dual-tasks.

Lateralized dual-task performance: the effects of spatial and muscular repositioning

In three experiments subjects were required to perform different manual tapping tasks using either the left or right hand while concurrently performing a speech task. The major independent variables examined were muscular effort and the spatial and muscular repositioning components of the tapping tasks. In all speech conditions right hand performance was disrupted more than left hand performance. The degree of this lateralized disruption did not alter as a function of variation in either muscular effort or the repositioning requirements of the manual task. However, muscular repositioning activity, unlike other components of the motor task, was affected bilaterally by the addition of the speech task. Overall the results suggest that the dual-task procedure can be used to assess two types of "lateralized" interference effects; one relating to right hand performance, the other to left hemisphere performance.

Syndrome analysis in clinical neuropsychology

The application of syndrome analysis in clinical practice has tended to rely on rather qualitative diagnoses by the neuropsychologist. The present paper proposes the use of a decision theory method which enables a systematic approach to be made to neuropsychological diagnosis. It is argued that the proposed method not only aids diagnostic decision making but also enables probabilities to be associated with particular prognostic statements. In this way the method is useful for guiding testing procedures and optimizing treatment programmes for particular patients.

Speech lateralization assessed by concurrent task performance

A sequential button pressing task using either the left or the right hand while concurrently performing a speech task was investigated. Subjects with left-hemisphere speech representation, determined by a dichotic monitoring task showed a lateralized practice effect: left-hand performance improved with practice during the speech task, but right-handed performance did not. Subjects with right-hemisphere speech representation showed disruption of either hand with concurrent speech, and no lateralized practice effect. The results from this study suggest the mechanisms mediating speech perception and speech production may not always be concordantly lateralized. A discriminant analysis of the data showed that 93% of subjects could be correctly classified according to side of representation of speech perception given the performance measures on the concurrent tasks.