A mixed-handed advantage in episodic memory: A possible role of interhemispheric interaction

Recent behavioral and brain imaging data indicate that performance on explicit tests of episodic memory is associated with interaction between the left and right cerebral hemispheres, in contrast with the unihemispheric basis for implicit tests of memory. In the present work, individual differences in strength of personal handedness were used as markers for differences in hemispheric communication, with mixed-handers inferred to have increased interhemispheric interaction relative to strong right-handers. In Experiment 1, memory for words was assessed via recall or word fragment completion. In Experiment 2, memory for real-world events was assessed via recall. Results supported the hypothesis, in that mixed-handers displayed better episodic memory in comparison with strong right-handers.     

A dynamic developmental theory of attention-deficit/hyperactivity disorder (ADHD) predominantly hyperactive/impulsive and combined subtypes

Attention-deficit/hyperactivity disorder (ADHD) is currently defined as a cognitive/behavioral developmental disorder where all clinical criteria are behavioral. Inattentiveness, overactivity, and impulsiveness are presently regarded as the main clinical symptoms. The dynamic developmental behavioral theory is based on the hypothesis that altered dopaminergic function plays a pivotal role by failing to modulate nondopaminergic (primarily glutamate and GABA) signal transmission appropriately. A hypofunctioning mesolimbic dopamine branch produces altered reinforcement of behavior and deficient extinction of previously reinforced behavior. This gives rise to delay aversion, development of hyperactivity in novel situations, impulsiveness, deficient sustained attention, increased behavioral variability, and failure to "inhibit" responses ("disinhibition"). A hypofunctioning mesocortical dopamine branch will cause attention response deficiencies (deficient orienting responses, impaired saccadic eye movements, and poorer attention responses toward a target) and poor behavioral planning (poor executive functions). A hypofunctioning nigrostriatal dopamine branch will cause impaired modulation of motor functions and deficient nondeclarative habit learning and memory. These impairments will give rise to apparent developmental delay, clumsiness, neurological "soft signs," and a "failure to inhibit" responses when quick reactions are required. Hypofunctioning dopamine branches represent the main individual predispositions in the present theory. The theory predicts that behavior and symptoms in ADHD result from the interplay between individual predispositions and the surroundings. The exact ADHD symptoms at a particular time in life will vary and be influenced by factors having positive or negative effects on symptom development. Altered or deficient learning and motor functions will produce special needs for optimal parenting and societal styles. Medication will to some degree normalize the underlying dopamine dysfunction and reduce the special needs of these children. The theory describes how individual predispositions interact with these conditions to produce behavioral, emotional, and cognitive effects that can turn into relatively stable behavioral patterns.     

Rightward biases in free-viewing visual bisection tasks: implications for leftward responses biases on similar tasks

Neurologically normal individuals exhibit strong leftward response biases during free-viewing perceptual judgments of brightness, quantity, and size. When participants view two mirror-reversed objects and they are forced to choose which object appears darker, more numerous, or larger, the stimulus with the relevant feature on the left side is chosen 60-75% of the time. This effect could be influenced by inaccurate judgments of the true centre-point of the objects being compared. In order to test this possibility, 10 participants completed three visual bisection tasks on stimuli known to elicit strong leftward response biases. Participants were monitored using a remote eye-tracking device and instructed to stare at the subjective midpoint of objects presented on a computer screen. Although it was predicted that bisection errors would deviate to the left of centre (as is the case in the line bisection literature), the opposite effect was found. Significant rightward bisection errors were evident on two of the three tasks, and the leftward biases seen during forced-choice tasks could be the result of misjudgments to the right of centre on these same tasks.     

Construct validity of the Balloon Analog Risk Task (BART): associations with psychopathy and impulsivity

To continue research assessing the validity of the Balloon Analog Risk Task (BART) as a measure of risk taking, the BART was administered to a nonforensic sample of individuals with varying levels of psychopathic characteristics. Construct validity of the BART was evaluated by measuring risk-taking behavior in relation to self-reported psychopathy, anxiety, psychophysiological data, and demographic variables. Supporting the construct validity of the BART, while controlling for variance accounted for by interrelated variables in the context of hierarchical regression analyses, higher self-reported psychopathy was significantly predictive of increased risk taking on the BART. Findings also revealed interesting gender differences in self-reported psychopathy and a trend for men to engage in riskier behavior. Limitations and research directions are presented.     

Enhancement of auditory fear conditioning after housing in a complex environment is attenuated by prior treatment with amphetamine

Prior exposure to drugs of abuse has been shown to occlude the structural plasticity associated with living in a complex environment. Amphetamine treatment may also occlude some cognitive advantages normally associated with living in a complex environment. To test this hypothesis we examined the influence of prior exposure to amphetamine on fear conditioning in rats housed in either a standard or complex environment. Housing in a complex environment facilitated fear learning to an auditory conditioned stimulus (CS), but not to the training context, relative to animals housed singly or in a social group. Prior treatment with amphetamine eliminated this effect. These results indicate that living in a complex environment facilitates conditional freezing to an auditory CS, and that this effect is abolished by pretreatment with amphetamine.     

Applying a psychoeducational perspective to ADHD

This article examines whether various cognitive abilities are associated with symptoms of ADHD. Cognitive ability is conceptualized using Cattell-Horn-Carroll (CHC) theory as measured using the Woodcock-Johnson Tests of Cognitive Ability (3rd ed.). This article also examines whether test session behavior mediates the association between cognitive ability and ADHD. Participants are children ages 6 to 12 with (n= 33) and without (n= 19) ADHD. Results show that inattentive symptoms of ADHD are significantly related to the CHC ability of processing speed above and beyond the effect of test session behavior. Symptoms of ADHD (both inattention and hyperactivity/impulsivity) are also significantly associated with visual spatial processing, but this is completely mediated by test session behavior. It is concluded that inattentive symptoms of ADHD are associated with slower processing speed and that this relationship is not explained by test session behavior.     

Cognitive behaviour therapy for panic disorder: long-term follow-up

This paper describes a long-term follow-up of patients with panic disorder who received cognitive behaviour therapy within a randomized controlled trial. Of 89 patients eligible for follow-up, 28 (31.5%) were reassessed 6-8 years after commencement of treatment in the trial. No differences were found between those who were followed up and those lost to follow-up on most baseline measures including measures of panic-related psychopathology, or depression. Outcomes at long-term follow-up were significantly better than baseline measures of panic, avoidance and depression. In this sub-sample the effect of cognitive behaviour therapy for panic disorder appears to maintain over the long-term.     

Body-esteem in Swedish 10-year-old children

This study examined body-esteem in 10-yr.-old children. The study group comprised 960 schoolchildren, 515 girls and 445 boys (M age= 10.4, SD=0.5). Analysis showed that girls who were overweight had more negative body-esteem on all dimensions (weight, appearance, and attribution). The overweight boys had more negative perceptions on only two dimensions (weight and appearance). Twice as many girls perceived themselves as too fat (20%) as too skinny (10%). Of the girls who perceived themselves as fat, only 31% were overweight; similarly only 33% of the boys who perceived themselves as fat were overweight. The children's perception of their weight seemed as important as their actual weight and was associated with their body-esteem in the same way. Although few children had dieted (7% of the girls and 5% of the boys), the ones who had dieted had more negative body-esteem than children who had not dieted.