Basal ganglia, dopamine and temporal processing: performance on three timing tasks on and off medication in Parkinson's disease

A pervasive hypothesis in the timing literature is that temporal processing in the milliseconds and seconds range engages the basal ganglia and is modulated by dopamine. This hypothesis was investigated by testing 12 patients with Parkinson's disease (PD), both 'on' and 'off' dopaminergic medication, and 20 healthy controls on three timing tasks. In a seconds range (30-120 s) time production task, patients tested 'on' medication showed a significantly different accuracy profile compared to controls and when tested 'off' medication. However, no group or on vs off medication differences in accuracy were found on a time reproduction task and a warned reaction time task requiring temporal processing within the 250-2000 ms range. Variability was measured using the coefficient of variation, with the performance of the patient group on the time reproduction task violating the scalar property, suggesting atypical temporal processing mechanisms. The data suggest that the integrity of the basal ganglia is necessary for 'typical' time production in the seconds range as well as for time reproduction at shorter intervals. Exploratory factor analysis suggested that the time production task uses neural mechanisms distinct from those used in the other two timing tasks. The dissociation of the effects of dopaminergic medication and nature of task on performance in PD raises interesting questions about the pharmacological mediation and task-specificity of deficits in temporal processing.     

Stimulus timing by people with Parkinson's disease

Previous literature suggests that Parkinson’s disease is marked by deficits in timed behaviour. However, the majority of studies of central timing mechanisms in patients with Parkinson’s disease have used timing tasks with a motor component. Since the motor abnormalities are a defining feature of the condition, the status of timing in Parkinson’s disease remains uncertain. Data are reported from patients with mild to moderate Parkinson’s disease (both on and off medication) and age- and IQ-matched controls on a range of stimulus timing tasks without counting. Tasks used were temporal generalization, bisection, threshold determination, verbal estimation, and a memory for duration task. Performance of patients was generally “normal” on all tasks, but significant differences from performance of controls were found on the memory for duration task. Among the “normal” effects noted were arithmetic mean bisection, asymmetric temporal generalization gradients, and subjective shortening on the memory for duration task. The results suggest (a) that some previous reports of timing “deficits” in Parkinson’s patients were possibly due to the use of tasks requiring a timed manual response and (b) small differences between patients and controls may be found on tasks where two stimuli are presented on each trial, whether patients are on medication or off it.     

The persistence of erroneous familiarity in an epileptic male: challenging perceptual theories of déjà vu activation

We report the case of a 39-year-old, temporal lobe epileptic male, MH. Prior to complex partial seizure, experienced up to three times a day, MH often experiences an aura experienced as a persistent sensation of déjà vu. Data-driven theories of déjà vu formation suggest that partial familiarity for the perceived stimulus is responsible for the sensation. Consequently, diverting attention away from this stimulus should cause the sensation to dissipate. MH, whose sensations of déjà vu persist long enough for him to shift his perceptual focus a number of times during the experience, spontaneously reports that these shifts make no difference to the sensation experienced. This novel observation challenges data-driven theories of déjà vu formation which have been used to explain the occurrence of déjà vu in those with temporal lobe epilepsy and the general population. Clearly, in epilepsy, erratic neuronal firing is the likely contributor, and in this paper we postulate that such brain firing causes higher-order erroneous 'cognitive feelings'. We tentatively extend this account to the general population. Rather than being a reaction to familiar elements in perceptual stimuli, déjà vu is likely to be the result of a cognitive feeling borne of the erroneous activation of neural familiarity circuits such as the parahippocampal gyrus, persisting as long as this activation persists.     

An evaluation of intraverbal training and listener training for teaching categorization skills

The effects of vocal intraverbal training and listener training on the emergence of untrained categorization skills were evaluated. Five typically developing preschool children initially learned to name a number of previously unfamiliar visual stimuli. Each child then received one of two types of training. Intraverbal training involved reinforcing vocally emitted category names by the child in the presence of a spoken exemplar name. Listener training involved reinforcing the selection of visual stimuli by the child in the presence of a spoken category name. A multiple baseline design was used to evaluate the effects of training on each child's intraverbal category naming and stimulus selection. Pre- and posttests were used to assess additional emergent relations. Four of 5 participants did not demonstrate the emergence of any untrained relations. The current findings suggest that additional research is needed to determine the optimal sequencing of conditions in programs designed to teach categorization skills.     

Influencing attitudes toward near and distant objects

It is argued that the temporal distance of attitude objects systematically changes how the object is mentally represented, and thus influences the strength of particular persuasive appeals. Three experiments tested the hypothesis that people preferentially attend to arguments that highlight primary, abstract (high-level) vs. incidental, concrete (low-level) features when attitude objects are temporally distant vs. near. Results suggested that when attitude objects are temporally distant vs. near, arguments emphasizing primary vs. secondary features (Study 1), desirability vs. feasibility features (Study 2), and general classes vs. specific cases are more persuasive (Study 3). The relation of construal theory to dual process theories of persuasion and persuasion phenomena, such as personal relevance effects and functional matching effects, are discussed.     

A survival guide to fission

The fission of a person involves what common sense describes as a single person surviving as two distinct people. Thus, say most metaphysicians, this paradox shows us that common sense is inconsistent with the transitivity of identity. Lewis’s theory of overlapping persons, buttressed with tensed identity, gives us one way to reconcile the common sense claims. Lewis’s account, however, implausibly says that reference to a person about to undergo fission is ambiguous. A better way to reconcile the claims of common sense, one that avoids this ambiguity, is to recognize branching persons, persons who have multiple pasts or futures.

Children with Comorbid Speech Sound Disorder and Specific Language Impairment are at Increased Risk for Attention-Deficit/Hyperactivity Disorder

This study focuses on the comorbidity between attention-deficit/hyperactivity disorder (ADHD) symptoms and speech sound disorder (SSD). SSD is a developmental disorder characterized by speech production errors that impact intelligibility. Previous research addressing this comorbidity has typically used heterogeneous groups of speech-language disordered children. This study employed more precise speech-language diagnostic criteria and examined ADHD symptomatology in 108 SSD children between the ages of 4 and 7 years old with specific language impairment (SLI) (n = 23, 14 males, 9 females) and without SLI (n = 85, 49 males, 36 females). We also examined whether a subcategory of SSD, persistent (n = 39, 25 males, 14 females) versus normalized SSD (n = 67, 38 males, 29 females), was associated with ADHD and/or interacted with SLI to predict ADHD symptomatology. Results indicated that participants in the SSD + SLI group had higher rates of inattentive ADHD symptoms than those in the SSD-only and control groups. In addition, an unexpected interaction emerged such that children with SLI and normalized-SSD had significantly higher ADHD inattentive ratings than the other subgroups. A proposed explanation for this interaction is discussed.     

The role of representational status and item complexity in parent–child conversations about pictures and objects

Mother–child conversations about pictures systematically differ from mother–child conversations about objects: Pictures are more likely than objects to elicit talk about kinds, whereas objects are more likely than pictures to elicit talk about individuals. The purpose of the current study is to examine whether this difference between pictures and objects is explained by differences in item complexity. Mothers and their 4-year-old children were randomly assigned to one of two conditions: simple or complex. In each condition, participants viewed 12 toy objects and 12 pictures, matched for content. The items were either highly detailed (complex condition) or very plain (simple condition). Replicating previous research, mothers and children provided relatively more focus on kinds when talking about pictures, and relatively more focus on individuals when talking about objects. The current results go further, however, to demonstrate that this effect is independent of the items’ complexity. We therefore propose that the picture–object difference is not due to low-level differences in amount of perceptual detail provided, but rather is due to the greater ease with which pictures serve as representations [DeLoache, J. S. (1991). Symbolic functioning in very young children: Understanding of pictures and models. Child Development, 62, 736–752]. These data indicate the ways in which a fundamental conceptual distinction between kinds and individuals arises in different linguistic expressions and in different contexts.     

Attentional focus moderates habituation–language relationships: slow habituation may be a good thing

An interesting paradox in the developmental literature has emerged in which fast‐habituating babies tend to be temperamentally difficult and fast language learners, even though temperamentally difficult babies tend to be slow language learners. The purpose of the present investigation was to examine whether the paradoxical relationships among habituation, temperamental difficulty, and language acquisition could be mediated partly or wholly by infant attentional focus, because the latter also tends to correlate with temperamental difficulty and vocabulary size. Forty mother–infant dyads were followed from child age 5–20‐months. Results replicated those of Tamis‐LeMonda and Bornstein (Child Develop 1989, 60, 738–751): measures of visual habituation at 5 months were related to 13‐month vocabulary. However, relationships between 5‐month habituation and 20‐month vocabulary were moderated by temperamental attentional focus. For children low in attentional focus, 5‐month habituation was related negatively to 20‐month productive vocabulary; whereas for children high in attentional focus, early habituation was positively related to later vocabulary. Results are consistent with a model of habituation in which volitional attentional focus overrides basic attentional mechanisms that occur during habituation. Copyright © 2008 John Wiley & Sons, Ltd.