Control of oscillatory force tasks: Low-frequency oscillations in force and muscle activity

Force variability during steady force tasks is strongly related to low-frequency oscillations (<0.25 Hz) in force. However, it is unknown whether low-frequency oscillations also contribute to the variability of oscillatory force tasks. To address this, twelve healthy young participants (21.08 ± 2.99 years, 6 females) performed a sinusoidal force task at 15% MVC at two different frequencies (0.5 and 1 Hz) with isometric abduction of the index finger. We recorded the force from the index finger and surface EMG from the first dorsal interosseous muscle and quantified the following outcomes: 1) trajectory variability and accuracy; 2) power spectrum of force and EMG bursting below 2 Hz; 3) power spectrum of the interference EMG from 4 to 60 Hz. The trajectory variability and error significantly increased from 0.5 to 1 Hz task (P < 0.01). Increased force oscillations <0.25 Hz contributed to greater trajectory variability and error for both the 0.5 and 1 Hz oscillatory task (R² > 0.33; P < 0.05). The <0.25 Hz oscillations in force were positively associated with greater power in the <0.25 Hz for EMG bursting (R² > 0.52; P < 0.01). The modulation of the interference EMG from 35 to 60 Hz was a good predictor of the <0.25 Hz force oscillations for both the 0.5 Hz task and 1 Hz task (R² > 0.66; P < 0.01). These results provide novel evidence that, similar to steady contractions, low-frequency oscillations of the motor neuron pool appear to be a significant mechanism that controls force during oscillatory force tasks.     

The enactment effect is due to more than guesses and beliefs

Three experiments examined whether the enactment effect - that is, higher recall of enacted than of corresponding non-enacted information - might be explained by guessing rates and performance expectancies. Experiment 1 checked whether the guessing rate of target items would be higher as a result of a narrowed sampling space defined by the enactment condition. By means of pre-experimental instructions, the subjects in Experiments 2 and 3 were induced to expect respectively a positive enactment effect, a negative enactment effect, or no difference in amount of recall of enacted and non-enacted materials. Experiment 2 had a within-subject design, Experiment 3 a between-subject design. The experiments failed to support the proposed explanations.     

Glucocorticoid-induced impairment of long-term memory retrieval in rats: an interaction with dopamine D2 receptors

This study investigated glucocorticoid-dopaminergic interactions in modulating retrieval of long-term memory in an inhibitory avoidance task. Young adult male rats were trained in one trial inhibitory avoidance task (0.5 mA, 3 s footshock). On the retention test given 48 h after training, the latency to re-enter the dark compartment of the apparatus was recorded. Systemically administered corticosterone (1 or 3 mg/kg) given to rats 30 min before retention testing impaired their memory retrieval, but the lower dose was more effective than the higher one. Administration of the dopamine (DA) D2 receptor antagonist sulpiride (6 or 20 mg/kg) 30 min before corticosterone attenuated the impairing effects of corticosterone (1 mg/kg) on memory retrieval. Administration of the DA D1 receptor antagonist SCH23390 (25 or 50 microg/kg) had no effect on corticosterone-induced impairment of memory retrieval. Further, applied doses of sulpiride or SCH23390 alone were ineffective in modulating memory retrieval. These findings provide evidence for the existence of an interaction between glucocorticoids and DA D2 receptor on memory retrieval process.     

How do young children determine location? Evidence from disorientation tasks

Previous studies show that following disorientation children use the geometry of an enclosed space to locate an object hidden in one of the corners [e.g. (Hermer, L., & Spelke, E. (1996). Modularity and development: A case of spatial reorientation. Cognition, 61, 195-232)]. These studies have used a disorientation procedure that involves rotating the viewer (with eyes closed). Here, we examine 18- to 25-month-olds' spatial coding in two disorientation tasks--involving either viewer or space rotation. Importantly, the rotational movements in both tasks could not be visually tracked. Children were tested in either task (viewer- or space-movement) from either inside or outside a triangular (isosceles) space (with one unique and two equivalent corners). In the viewer-movement task, performance was above chance, regardless of which corner contained the object. In the space-movement task, performance was above chance at only the unique corner. On both tasks, performance was better from inside the space than from outside. The implications for how children determine location are discussed.     

Learning to control brain activity: a review of the production and control of EEG components for driving brain-computer interface (BCI) systems

Brain-computer interface (BCI) technology relies on the ability of individuals to voluntarily and reliably produce changes in their electroencephalographic (EEG) activity. The present paper reviews research on cognitive tasks and other methods of generating and controlling specific changes in EEG activity that can be used to drive BCI systems. To date, motor imagery has been the most commonly used task. This paper explores the possibility that other cognitive tasks, including those used in imaging studies, may prove to be more effective. Other factors which influence performance are also considered in relation to selection of tasks, as well as training of subjects.     

AN EVALUATION OF LABELING-THEN-DOING WITH MODERATELY HANDICAPPED PERSONS: ACQUISITION AND GENERALIZATION WITH COMPLEX TASKS

We conducted two experiments in which moderately mentally retarded persons were trained first to label and then to enter characters into a computer, calculator, or checkbook (label-then-do) within a multiple baseline design. In Experiment 1, 5 young adults were trained to enter statistical programs into computers in an office setting. Following training, all subjects' use of verbal labels and key-entry skills generalized across tasks (programs) and settings (offices and computer terminals). In Experiment 2, 3 junior high school students were trained with self-labeling procedures to complete a key-entry task and to balance a checkbook. The performance of all students generalized across tasks and settings, and the use of labels generalized for 2 of the students. Results are discussed relative to mediated generalization and to establishing verbal control over behavior.     

Inhibitory phonetic priming: Where does the effect come from?

Both phonological and phonetic priming studies reveal inhibitory effects that have been interpreted as resulting from lexical competition between the prime and the target. We present a series of phonetic priming experiments that contrasted this lexical locus explanation with that of a prelexical locus by manipulating the lexical status of the prime and the target and the task used. In the related condition of all experiments, spoken targets were preceded by spoken primes that were phonetically similar but shared no phonemes with the target (/bak/–/dεt/). In Experiments 1 and 2, word and nonword primes produced an inhibitory effect of equal size in shadowing and same–different tasks respectively. Experiments 3 and 4 showed robust inhibitory phonetic priming on both word and nonword targets in the shadowing task, but no effect at all in a lexical decision task. Together, these findings show that the inhibitory phonetic priming effect occurs independently of the lexical status of both the prime and the target, and only in tasks that do not necessarily require the activation of lexical representations. Our study thus argues in favour of a prelexical locus for this effect.     

Delayed N2 response in Go condition in a visual Go/Nogo ERP study in children who stutter

Purpose of the studyThe main aim of the study was to investigate the attentional and inhibitory abilities and their underlying processes of children who stutter by using behavioural measurement and event-related potentials (ERP) in a visual Go/Nogo paradigm.MethodsParticipants were 11 children who stutter (CWS; mean age 8.1, age range 6.3–9.5 years) and 19 typically developed children (TDC; mean age 8.1, age range 5.8–9.6 years). They performed a visual Go/Nogo task with simultaneous EEG recording to obtain ERP responses.ResultsResults showed that CWS had longer N2 and P3 latencies in the Go condition compared to the TDC. In contrast, the groups did not differ significantly in the Nogo condition or behavioural measures.ConclusionsOur findings did not confirm less efficient inhibitory control in CWS but suggest atypical attentional processing such as stimulus evaluation and response selection.Educational Objectives: The reader will be able to (a) describe recent findings on attention and inhibitory control in children who stutter, (b) describe the measurement of attentional processing, including inhibitory control, and (c) describe the findings on attentional processing in children who stutter as indexed by the event-related potentials in a visual Go/Nogo paradigm.     

Inhibitory control and the onset of combustible cigarette,e-cigarette,and hookah use in early adolescence: The moderating role of socioeconomic status

The purpose of the study was to test the moderating influence of socioeconomic status (SES) on the associations between inhibitory control and the onset of combustible cigarette, electronic (e-) cigarette, and hookah use in early adolescence. A total of 407 adolescents self-reported nicotine use, inhibitory control, and SES. The hypothesis that inhibitory control would be significantly associated with nicotine use onset (i.e., combustible cigarettes, e-cigarettes, and hookah) only under the condition of low SES was tested. Direct associations were found for inhibitory control on “ever use” of all three nicotine use variables. A moderating effect was also found whereby low inhibitory control was significantly associated with nicotine use onset when participants were from low, but not high, SES families. Findings illustrate one contextual condition under which inhibitory control is associated with early onset of nicotine use.     

PROVIDING A MORE APPROPRIATE EDUCATION FOR SEVERELY HANDICAPPED PERSONS: INCREASING AND VALIDATING FUNCTIONAL CLASSROOM TASKS

We evaluated a teacher training and supervision program for increasing the involvement of severely handicapped adolescents and adults in functional educational tasks. The program, consisting of a brief in-service followed by supervisory prompts and feedback, was accompanied by large increases in functional tasks in three classrooms. In addition, generalized increases occurred during nontargeted times in the classroom and the changes during both the targeted and nontargeted times were maintained over a 44–45 week period. In two subsequent experiments, surveys provided social validation for the criteria for functional versus nonfunctional tasks in that: (a) relevant individuals reliably categorized functional tasks as representing typical living, work, social, and leisure situations and (b) experienced clinicians consistently rated tasks previously categorized as functional as being more useful for severely handicapped persons than tasks categorized as nonfunctional. Results are discussed in terms of the relationship of functional classroom tasks in the overall provision of appropriate educational services for severely handicapped students.