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Combined effects of ethanol and diazepam on performance and acquisition of serial position sequences by pigeons.

The effects of diazepam and ethanol, alone and in combination, were studied in pigeons responding under acquisition and performance chain schedules. Both diazepam and ethanol increased the number of pecks on the incorrect key (errors). Under the acquisition schedule both diazepam and ethanol increased errors at doses lower than those under the performance schedule. Under both schedules effects of combinations of ethanol and diazepam were usually greater than the sum of the effects of the individual drugs.

Animals↗

Marijuana: effects on storage and retrieval of prose material.

In a two phase design, an attempt was made to differentiate the effect of marijuana on the storage and retrieval of prose material. In the first phase, 40 male subjects were administered a single 500 mg marijuana cigarette containing 2.1%delta9-THC or a placebo cigarette. Fifteen minutes after smoking, they listened to and at the same time read a narrative passage of approximately 200 words in length. Subsequently, an immediate free recall test was given in which subjects were required to write down as much of the story as they could remember. The second phase was conducted 24h later. Marijuana and placebo subjects were randomly subdivided into four groups with half of the subjects participating in the same drug condition as occurred on day one while the others switched drug state. Fifteen minutes after smoking, all subjects recalled the passage presented on day one and then were given 24 questions concerning facts and events in the story which could be answered in a few words. These questions served as retrieval cues. Following this, a new passage was presented in the same manner as occurred on day one. After an immediate free recall test, another cued recall test was administered. Results indicated that marijuana reduced immediate recall under both cued and uncued conditions incomparison to placebo. No relative cued recall advantage was found in the marijuana groups for the old or new story and marijuana produced only a moderate decrement in recall of the old story on day two. However, marijuana given in the second phase significantly reduced memory for items recalled in the initial phase irrespective of drug or cueing condition in phase one, suggesting that retrieval was also affected. Some decrement in recall of the new story did occur as a function of drug state change in group M-P. This effect was related to the serial position of input items. Serial position did not interact with drug state under any other recall condition.

Cannabis↗

Responsiveness of Western adults to pitch-distributional information in melodic sequences.

Responsiveness of musically trained and untrained adults to pitch-distributional information in melodic contexts was assessed. In Experiment 1, melodic contexts were pure-tone sequences, generated from either a diatonic or one of four nondiatonic tonesets, in which pitch-distributional information was manipulated by variation of the relative frequency of occurrence of tones from the toneset. Both the assignment of relative frequency of occurrence to tones and the construction of the (fixed) temporal order of tones within the sequences contravened the conventions of western tonal music. A probe-tone technique was employed. Each presentation of a sequence was followed by a probe tone, one of the 12 chromatic notes within the octave. Listeners rated the goodness of musical fit of the probe tone to the sequence. Probe-tone ratings were significantly related to frequency of occurrence of the probe tone in the sequence for both trained and untrained listeners. In addition, probe-tone ratings decreased as the pitch distance between the probe tone and the final tone of the sequence increased. For musically trained listeners, probe-tone ratings for diatonic sequences tended also to reflect the influence of an internalized tonal schema. Experiment 2 demonstrated that the temporal location of tones in the sequences could not alone account for the effect of frequency of occurrence in Experiment 1. Experiment 3 tested musically untrained listeners under the conditions of Experiment 1, with the exception that the temporal order of tones in each sequence was randomized across trials. The effect of frequency of occurrence found in Experiment 1 was replicated and strengthened.

Adolescent↗

The programming of structural properties of movement sequences.

The present paper investigates the role of abstract structural properties in the programming and execution of movement sequences. Three experiments, using converging methods, demonstrate that the motor system represents the abstract structural properties of movement sequences. The first two experiments show that hierarchical structures over a sequence of tapping movements can be used to prepare the motor program, even if the specific elements of the sequence are still unknown. Experiment 2 also shows that the preliminary programming of structural properties of a movement sequence takes more time than the programming of specific elements (start elements). Experiment 3 suggests that abstract structural properties can be generalized from a special sequence and that they are transferable to other sequences. Abstract structural properties are assumed to be an important component of generalized motor programs.

Attention↗

Programming time in serial tapping responses as a function of pathway constraint.

This study varied the accuracy demand within a linear series of targets to investigate the effect of movement-pathway constraints on response-programming time. Sidaway, Christina, and Shea (1988) have suggested that constraints placed upon movement initiation by the demand for response precision may play an important role in determining the length of the programming process. By varying the subtended angles of a series of three targets, this experiment tested the specific prediction of Sidaway et al. that programming time may be a function of the target, within a line of targets, that subtends the smallest angle at the start position. It is this target that demands the greatest precision in the movement pathway. Subjects participated in a series of conditions in which the size and placement of the target that imposed the maximal constraint was varied. In each condition the subjects were required to strike a series of three targets with a stylus in a simple reaction-time paradigm. Analysis of the reaction-time results revealed a significant effect of size of constraint, but no effect of position of constraint. Analysis of the movement-time data dispelled movement-duration and movement-velocity interpretations of the results and intimated a possible online trajectory-correction process.

Adolescent↗

Short-term serial recall in ADDH, normal, and reading-disabled boys.

Short-term retention of verbal items of span and subspan length was examined in hyperactive (ADDH), normal and non-ADDH reading-disabled boys. Performance of ADDH and normal boys did not differ on three measures of verbal serial recall. Thus, it appears that the cognitive deficits of ADDH children cannot be attributed to deficient retention of stimuli. In contrast, reading-disabled (RD) boys performed significantly more poorly than both normal and ADDH boys when required to recall verbal items following "filled" delay intervals in which the children were required to perform a competing verbal activity. The results suggest that verbal encoding of RD children is particularly vulnerable to interference from other verbal stimuli. ADDH and RD children may represent subsamples of children demonstrating academic difficulties, with each group showing a characteristic pattern of cognitive deficits.

Attention↗

Seriators' and nonseriators' comprehension of comparative adjective forms.

The relationship between comprehension of relational adjective forms and seriation ability was assessed for 60 children aged 4-6. Three groups, operational seriators, intuitive seriators, and nonseriators, were given a test measuring comprehension of affirmative and negative comparative and equative forms. Results indicated that operationals understood more forms than intuitives and that intuitives comprehended more than nonseriators. When age differences between groups were minimized, the latter but not the former difference was preserved. This suggests that significant growth in linguistic comprehension accompanies the emergence of the ability to order objects by size. Analysis of errors indicated that nonseriators interpreted statements dichotomously and ignored the standard more than seriators. Findings help to clarify the relationship between linguistic and cognitive development for parallel underlying structures.

Child↗

Event order versus syntactic structure in recall of adverbial complex sentences.

Two experiments using recall of sentences examined two contrasting principles of clause ordering in a type of complex sentences: the main-clause-first (syntactic) principle and the event-order (or temporal-causal order) principle. In Experiment 1, these two principles were studied in complex sentences with a main clause and a subordinate adverbial clause-e.g., "When she heard the thunder, she stopped playing Frisbee." In sentences of this type the subordinate clause typically describes a temporally or causally antecedent event, while the main clause describes a subsequent event in the temporal-causal sequence. These two principles make opposite predictions on what is the psychologically simpler or preferred order of the two clauses in this type of complex sentence. Results of Experiment 1 showed an overall preference in memory for main-clause-first order. In Experiment 2, complex sentences with a main clause and a subordinate clause not temporally or causally related were also used in a sentence recall task. Similar results were obtained. The implication of these findings for the determinants of linguistic structures was discussed.

Adult↗

Diminished cerebral metabolic response to motor stimulation in schizophrenics: a PET study.

Positron emission tomography (PET) and the deoxyglucose method were used to measure cerebral metabolism in 14 normals and 13 schizophrenics at rest and during performance of simple and complex finger-movement sequences. The normals, but not the schizophrenics, showed significant metabolic activation in mesial frontal and contralateral sensorimotor and premotor regions during the complex movement. The relative metabolism of schizophrenics was significantly lower than normal in frontal regions and higher than normal in thalamus and basal ganglia under all scanning conditions. The results suggest that schizophrenics may have a brain dysfunction which limits their capacity to produce a focal metabolic response to stimulation in several functionally distinct brain regions.

Adult↗

Sequential and simultaneous processing abilities of high-functioning autistic and language-impaired children.

Investigated the Sequential and Simultaneous processing distinctions of high-functioning autistic children and children with a developmental receptive language disorder (DRLD). Twenty autistic subjects and 20 DRLD subjects were matched on age and gender, and compared to each other on their Sequential and Simultaneous processing abilities utilizing the K-ABC and selected subtests of the WISC-R. Results showed that both groups manifested a relative sequential processing deficit. However, the groups did not differ significantly on their overall sequential and simultaneous processing capabilities relative to their degree of language impairment. The application of the sequential and simultaneous processing model to the WISC-R provided consistent convergent and discriminant validation for the assessment of these processes with the WISC-R.

Aptitude↗

Changing patterns of intellectual strengths and weaknesses in males with fragile X syndrome.

Examined the changing profiles of intelligence in males with fragile X syndrome as these individuals increased in chronological age. Using a psychometric instrument designed to measure styles of information processing, 21 males aged 4 to 27 years were examined cross-sectionally in sequential processing, simultaneous processing, and achievement. The age of the subject was associated with age-equivalent levels of both simultaneous processing and achievement, but fragile X males did not show higher levels of sequential processing with increasing chronological age. Compared to younger fragile X males, the older subjects were more delayed in sequential processing skills relative to their in other areas. A smaller longitudinal study confirmed the presence of a plateau in sequential processing among those subjects tested two times after the age of 10 years. Implications are discussed for diagnosis, intervention, and the matching of subject groups in mental retardation research.

Achievement↗

[Standardization of a motor performance series for measuring fine motor disorders in Parkinson disease].

Some 114 patients with idiopathic Parkinson's disease (not demented, no tremor dominance; mean age: 67.0 years; mean duration of illness: 6.1 years) were subjected to the manual dexterity test "MLS" ("Motorische Leistungs Serie"). A retest was carried out 24 h later with no change in medication. Thus, adequate conditions were present for testing the stability of dimensions of manual dexterity. In addition, data from the initial measurement were normalized (T norms). The correlations of the values from both measurements (retest reliability) underscore the constancy of manual dexterity functions. Subtest show adequate stability of measurement so that they can be used for diagnosing dexterity disturbances in individual patients. Charts listing normal values and critical differences allow intra- and interindividual comparisons. It is thus possible to make statistically sound predictions for individual patients concerning the effectiveness of therapy or progression of illness with respect to manual dexterity. In addition, differences on the left and right sides can be tested for statistic significance.

Aged↗

Nicotine-induced enhancement of attention in the five-choice serial reaction time task: the influence of task demands.

RATIONALE: Beneficial effects of nicotine on cognitive processes including attention have potential therapeutic uses and have been proposed as incentives for tobacco smoking. OBJECTIVES: To establish task conditions under which the effects of nicotine on attention are obtained reliably and to characterise such effects further. METHODS: Rats were trained in a modified version of the five-choice serial reaction time task (5-CSRTT) to detect 1-s light stimuli with greater than 70% accuracy and fewer than 20% omission errors. Nicotine was tested under different task requirements by varying signal event rate, stimulus duration and stimulus predictability, and by introducing white-noise distractors. RESULTS: Nicotine (0.05-0.2 mg/kg, s.c.) repeatedly improved accuracy and reduced omission errors and reaction times, leading to increases in numbers of reinforcers earned. Anticipatory responding was increased. Parametric modifications intended to increase demands on sustained attention did not affect performance in a manner suggesting that this subtype of attention was being taxed, and the effects of nicotine were not more marked under such conditions. Shorter stimulus durations impaired performance, but this manipulation weakened the effect of nicotine on accuracy. In contrast, the presence of noise distractors facilitated the effects of nicotine to the extent that distractor-induced impairments were abolished by the drug. CONCLUSIONS: The 5-CSRTT can provide a sensitive rodent model for the attention-enhancing effects of nicotine. Changes made to the procedure may have increased its sensitivity to nicotine, particularly with respect to accuracy. There were indications that the effects of nicotine were largest on processes of selective attention or on disengaging attention from irrelevant events and shifting it to behaviourally significant stimuli.

Analysis of Variance↗

Deficits in a sustained attention task following nicotine withdrawal in rats.

OBJECTIVE: Behavioural consequences of spontaneous and antagonist-precipitated withdrawal from nicotine upon performance of rats were compared alongside non-nicotinic antagonists in the 5-choice serial reaction time task (5-CSRTT). METHODS: Male hooded Lister rats were trained to detect and respond to brief flashes of light presented every 15 s in one of five holes until a stable level of performance was achieved. RESULTS: Surgical removal of osmotic minipumps from rats having received nicotine (3.16 mg/kg per day base SC) chronically for 7 days produced marked deficits in performance. Compared to saline-treated controls, deficits were apparent 10 h and 16 h following nicotine abstinence; the percentage of omission errors increased concomitantly with modest decreases in response accuracy. Tests conducted 34 h and 106 h post-withdrawal indicated a progressive and complete recovery in attention performance, respectively. In another experiment, following the exposure to the same nicotine regime, administration of the competitive nicotine receptor antagonist dihydro-beta-erythroidine precipitated immediate deficits in performance that were greater than those observed in saline-treated subjects. Methyllycaconitine, an alpha(7) nicotinic receptor antagonist failed to precipitate attention deficits in nicotine-treated rats. Tests with SCH23390 and raclopride produced impairments that were similar in profile to nicotine withdrawal contrasting with non-specific effects of dizocilpine. CONCLUSIONS: These results provide evidence of a cognitive impairment resulting from nicotine deprivation in rodents. Specifically, blockade of D(1) receptors by SCH23390 produced decrements in performance that were qualitatively similar but greater in magnitude to the alterations observed following nicotine withdrawal. Overall, assessing nicotine withdrawal in the 5-CSRTT presents an animal model that exhibits robust construct and face validity.

Animals↗

Impaired performance of alpha7 nicotinic receptor knockout mice in the five-choice serial reaction time task.

RATIONALE: Nicotinic receptors have been implicated in attentional performance. Nicotine can improve attention in animals and humans, but knowledge about relevant receptor subtypes is very limited. OBJECTIVES: The aim was to examine the role of alpha7 receptors in attentional performance of mice and in effects of nicotine. MATERIALS AND METHODS: Mice with targeted deletion of the gene coding for the alpha7 subunit of nicotinic receptors and wild-type controls were trained on a five-choice serial reaction time task with food reinforcers presented under varying parametric conditions. Nicotine was administered in a range of doses (0.001-1.0 mg/kg sc), including those reported to enhance attentional performance. RESULTS: Initially the alpha7(-/-) (knockout) mice responded less accurately and made more anticipatory responses. After task parameters were altered so that the time allowed for responding was reduced and anticipatory (impulsive) responses were punished by a time-out, the pattern of performance deficits changed; there were increased omission errors in alpha7(-/-) mice but normal levels of accuracy and anticipatory responding. Nicotine did not improve any measure of performance, either with the original training parameters or after retraining; the largest dose used (1.0 mg/kg) produced a general impairment of responding in alpha7(-/-) and wild-type mice. CONCLUSIONS: alpha7 nicotinic receptor knockout mice are impaired in performance of the 5-CSRTT, suggesting a possible role for alpha7 receptors in attentional processing. However, identification of a protocol for assessing attention-enhancing effects of nicotine in mice may require further modifications of test procedures or the use of different strains of animal.

Animals↗

Cardiovascular reactivity to mental stress is not affected by alpha2-adrenoreceptor activation or inhibition.

RATIONALE: It has been postulated that cardiovascular reactivity to mental stress varies with tonic central sympathetic nervous system activity, but pharmacological evidence is missing. OBJECTIVE: To test whether modulation of central sympathetic nervous system activity by alpha2-adrenergic agonism and antagonism affects cardiovascular reactivity to mental stress. MATERIALS AND METHODS: On three five-stepped dose/concentration-response study days, 12 healthy male volunteers received intravenous infusions of dexmedetomidine (alpha2-agonist, target plasma concentrations: 0.04-0.32 ng/ml), yohimbine (alpha2-antagonist, doses: 0.016-0.125 mg/kg), and placebo, respectively. During each dose step, subjects performed a 5-Choice Reaction Time Task (CRTT) and a Paced Auditory Serial Addition Task (PASAT) to induce moderate mental stress. Prestress baseline, as well as stress-induced responses of heart rate, and noninvasive finger arterial blood pressure (Finapres) were assessed. RESULTS: Prestress baseline heart rate and blood pressure decreased with increasing doses of dexmedetomidine and increased with increasing doses of yohimbine. However, dexmedetomidine and yohimbine did not affect stress-induced heart-rate and blood-pressure changes. CONCLUSIONS: Cardiovascular reactivity to mental stress is not related to pharmacologically manipulated tonic central sympathetic nervous system activity by alpha2-adrenergic agonists and antagonists. These results do not support the assumption that cardiovascular reactivity is an index of tonic central sympathetic nervous system activity.

Adrenergic alpha-2 Receptor Agonists↗