Speech and nonspeech sequence skill learning in adults who stutter.

UNLABELLED: Two studies compared the speech and nonspeech sequence skill learning of nine persons who stutter (PWS) and nine matched fluent speakers (PNS). Sequence skill learning was defined as a continuing process of stable improvement in speed and/or accuracy of sequencing performance over practice and was measured by comparing PWS's and PNS's performance curves of accuracy, reaction time, and sequence duration, as well as retention and transfer. In experiment one, participants completed a 30-trial finger tapping sequence and in experiment two, a 30-trial read-aloud sequence of nonsense syllables. Significant between-group differences were found in the speed of sequencing performance after practice, and on retention and transfer tests. These results partially supported the inference that PWS demonstrated differences in early stages of sequence skill learning compared to PNS. EDUCATIONAL OBJECTIVES: As a result of this activity the participant will be able to: (1) define skill learning and the important indicators of skill learning; (2) summarize the reviewed literature concerning the performance of PWS on speech and nonspeech sequencing tasks over practice; and (3) explain the implication of reaction time differences over practice between PWS and PNS.

Psychiatric symptoms following surgery for Parkinson's disease with an emphasis on subthalamic stimulation.

Bilateral subthalamic stimulation is a very effective neurosurgical treatment for advanced Parkinson's disease. Despite the range and frequency of psychiatric symptoms occurring in the postoperative state, most of these symptoms are transient and manageable. In clinical practice, preoperative psychiatric vulnerability, as with that of preoperative cognitive status, takes on an important role. Psychiatric assessment and active preoperative and postoperative intervention can potentially modify psychiatric outcomes. These psychiatric and psychological issues will take on greater importance, particularly with the rapid expansion of the number of neurosurgical sites and the need for adequate assessment and optimal management of patients. The paucity of the literature underscores the need for well-designed studies on psychiatric issues investigating both pathophysiology and clinical outcomes.

Involvement of human thalamus in the preparation of self-paced movement.

Cortical areas participating in the preparation of voluntary movements have been studied extensively. There is emerging evidence that subcortical structures, particularly the basal ganglia, also contribute to movement preparation. The thalamus is connected to both the basal ganglia and the cerebellar pathways, but its role in movement preparation has not been studied extensively in humans. We studied seven patients who underwent deep brain stimulation (DBS) electrode implantation in the thalamus for treatment of tremor (six patients) and myoclonus-dystonia (one patient). We recorded from the DBS contacts and scalp simultaneously, while patients performed self-paced wrist extension movements. Post-surgical MRI was used for precise localization of the DBS contacts in six patients. Back-averaging of the scalp recordings showed a slow negative movement-related potential (MRP) in all patients (onset 1846 +/- 189 ms prior to electromyography onset), whereas DBS electrode recordings showed pre-movement MRP in five out of seven patients. The thalamic MRP preceded both contralateral and ipsilateral wrist movements. There was no significant difference between the onset time of thalamic MRP (-2116 +/- 607 ms) and cortical MRP. Neither the scalp nor the thalamus showed pre-movement potentials with passive wrist extensions in two patients. In four patients with postoperative MRI who had thalamic MRP, the maximum amplitude or phase reversal occurred at contacts located in the ventral lateral nucleus. Frequency analysis was performed in the five patients with thalamic MRP. The medial frontocentral scalp contacts and the thalamic contacts with maximum MRP amplitude showed two discrete frequency bands in the alpha (mean peak 9 Hz) and beta (mean peak 17 Hz) range. Both frequency bands showed pre-movement event-related desynchronization (ERD). In the grand average, alpha and beta ERD in the scalp and beta ERD in the thalamus began 2.5-2.8 s prior to the onset of movement. However, the thalamic alpha ERD began considerably later, at 1.2 s before EMG onset. The beta band showed cortico-thalamic coherence from the beginning of the baseline period until approximately 0.5 s before the onset of movement. There was no cortico-thalamic coherence in the alpha band. Our findings suggest that the cerebellar thalamus is involved early in the process of movement preparation. Different cortico-subcortical circuits may mediate alpha and beta oscillations. During movement preparation, the motor thalamus and the supplementary motor area predominantly interact in the beta band.

Long-term follow up of bilateral deep brain stimulation of the subthalamic nucleus in patients with advanced Parkinson disease.

OBJECT: The use of deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been associated with a marked initial improvement in individuals with advanced Parkinson disease (PD). Few data are available on the long-term outcomes of this procedure, however, or whether the initial benefits are sustained over time. The authors present the long-term results of a cohort of 25 individuals who underwent bilateral DBS of the STN between 1996 and 2001 and were followed up for 1 year or longer after implantation of the stimulator. METHODS: Patients were evaluated at baseline and repeatedly after surgery by using the Unified Parkinson's Disease Rating Scale (UPDRS); the scale was applied to patients during periods in which antiparkinsonian medications were effective and periods when their effects had worn off. Postoperative UPDRS total scores and subscores, dyskinesia scores, and drug dosages were compared with baseline values, and changes in the patients' postoperative scores were evaluated to assess the possibility that the effect of DBS diminished over time. In this cohort the median duration of follow-up review was 24 months (range 12-52 months). The combined (ADL and motor) total UPDRS score during the medication-off period improved after 1 year, decreasing by 42% relative to baseline (95% confidence interval [CI 35-50%], p < 0.001) and the motor score decreased by 48% (95% CI 42-55%, p < 0.001). These gains did diminish over time, although a sustained clinical benefit remained at the time of the last evaluation (41% improvement over baseline, 95% CI 31-50%; p < 0.001). Axial subscores at the time of the last evaluation showed only a trend toward improvement (p = 0.08), in contrast to scores for total tremor (p < 0.001), rigidity (p < 0.001), and bradykinesia (p = 0.003), for which highly significant differences from baseline were still present at the time of the last evaluation. Medication requirements diminished substantially, with total medication doses reduced by 38% (95% CI 27-48%, p < 0.001) at 1 year and 36% (95% CI 25-48%, p < 0.001) at the time of the last evaluation; this decrease may have accounted, at least in part, for the significant decrease of 46.4% (95% CI 20.2-72.5%, p = 0.007) in dyskinesia scores obtained by patients during the medication-on period. No preoperative demographic variable, such as the patient's age at the time of disease onset, age at surgery, sex, duration of disease before surgery, preoperative drug dosage, or preoperative severity of dyskinesia, was predictive of long-term outcome. The only predictor of a better outcome was the patient's preoperative response to levodopa. CONCLUSIONS: In this group of patients with advanced PD who underwent bilateral DBS of the STN, sustained improvement in motor function was present a mean of 2 years after the procedure, and sustained reductions in drug requirements were also achieved. Improvements in tremor, rigidity, and bradykinesia were more marked and better sustained over time than improvements in axial symptoms. A good preoperative response to levodopa predicted a good response to surgery.

Neuropsychology for movement disorders neurosurgery.

The neuropsychologist plays a crucial role in three phases of the neurosurgical treatment of movement disorder patients, namely screening, outcome evaluation and research. In screening patients, the differential diagnosis of dementia, impact of depression or other psychiatric conditions, and the influence of disease and medication-induced symptoms on cognitive performance must be determined. Postoperatively, systematic evaluations elucidate the cognitive costs or benefits of the procedure. The neuropsychologist is then able to provide feedback and counselling to the professional staff, patient and family to inform management strategies. Neuropsychologists also study alteration of cognitive processing due to lesions or stimulation, which, in tandem with functional imaging, shed light on plasticity in cortical and subcortical processing.

Frontal-striatal circuit functions: context, sequence, and consequence.

The exact role of the basal ganglia in both the motor and non-motor domains has proven elusive since it is virtually impossible to refer to its function in isolation of cortical, and especially frontal cortical circuits. The result is that we often speak of frontal-striatal circuits and functions but this still leaves us in the dark when trying to specify basal ganglia information processing. A critical review of the data from both basic science and clinical studies suggests that we should break down processing along a temporal continuum, including the domains of context, sequential information processing, and feedback or reinforcement (i.e., the consequences of action). This analysis would cut across other theoretical constructs, such as attention, central executive, memory, and learning functions, traditionally employed in the neuropsychological literature. Under specified behavioral constraint, the basal ganglia can then be seen to be involved in fundamental aspects of attentional control (often covert), in the guidance of the early stages of learning (especially reinforcement-based, but also encoding strategies in explicit paradigms), and in the associative binding of reward to cue salience and response sequences via dopaminergic mechanisms. Parkinson's disease is considered to offer only a limited view of basal ganglia function due to partial striatal depletion of dopamine and the potential involvement of other structures and transmitters in its pathology. It is hoped that the present formulation will suggest new heuristic research strategies for basal ganglia research, permitting a closer link to be established between neurophysiological, functional imaging and neuropsychological paradigms.

Localization of clinically effective stimulating electrodes in the human subthalamic nucleus on magnetic resonance imaging.

OBJECT: The authors sought to determine the location of deep brain stimulation (DBS) electrodes that were most effective in treating Parkinson disease (PD). METHODS: Fifty-four DBS electrodes were localized in and adjacent to the subthalamic nucleus (STN) postoperatively by using magnetic resonance (MR) imaging in a series of 29 patients in whom electrodes were implanted for the treatment of medically refractory PD, and for whom quantitative clinical assessments were available both pre- and postoperatively. A novel MR imaging sequence was developed that optimized visualization of the STN. The coordinates of the tips of these electrodes were calculated three dimensionally and the results were normalized and corrected for individual differences by using intraoperative neurophysiological data (mean 5.13 mm caudal to the midcommissural point [MCP], 8.46 mm inferior to the anterior commissure-posterior commissure [AC-PC], and 10.2 mm lateral to the midline). Despite reported concerns about distortion on the MR image, reconstructions provided consistent data for the localization of electrodes. The neurosurgical procedures used, which were guided by combined neuroimaging and neurophysiological methods, resulted in the consistent placement of DBS electrodes in the subthalamus and mesencephalon such that the electrode contacts passed through the STN and dorsally adjacent fields of Forel (FF) and zona incerta (ZI). The mean location of the clinically effective contacts was in the anterodorsal STN (mean 1.62 mm posterior to the MCP, 2.47 mm inferior to the AC-PC, and 11.72 mm lateral to the midline). Clinically effective stimulation was most commonly directed at the anterodorsal STN, with the current spreading into the dorsally adjacent FF and ZI. CONCLUSIONS: The anatomical localization of clinically effective electrode contacts provided in this study yields useful information for the postoperative programming of DBS electrodes.