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PubMed2003

Reduction of lateral asymmetries in dribbling: the role of bilateral practice.

The influence of bilateral practice on the modification of well-established lateral asymmetries of performance was investigated in overlearned motor skills related to soccer in 12- to 14-year-old adolescent players. The participants had extensive practice before entering the experiment and were trained 2 hours per day, five times per week, during a period of 4 months. In the training, the participants were assigned to one of two groups: practice with emphasis on the preferred leg (PL), or practice with emphasis on the nonpreferred leg (NpL). Lateral asymmetries of performance were assessed before and after training on three motor tasks: kicking for force, kicking for accuracy, and speed of dribbling. The analysis of the results indicated a consistent asymmetry of performance throughout the tests, favouring the preferred leg. The asymmetry of performance was maintained at a constant level across the tests for the kicking tasks in both experimental groups. For speed of dribbling, however, the index of lateral asymmetry was reduced from the pre- to the post-test in the NpL group only, which was due to a higher rate of improvement with the nonpreferred leg after the experimental training. These results are indicative of the role played by bilateral practice in modifying lateral asymmetries of performance established as a consequence of previous unilateral training.

Journal Article↗
PubMed1977

A behavioral approach to obesity.

For many individuals, the practice of overeating is crucial in the development and maintenance of the obese state. Behavior theory views excessive eating leading to obesity as an overlearned habit, strongly conditioned to numerous internal and external cues. A number of studies are reviewed that assess the relationship between emotional arousal and food consumption. Obese persons who successfully lost and maintained a weight loss appeared able to reduce the number of inappropriate stimuli they previously responded to with food intake. The specific behavior modification techniques employed to change eating patterns are discussed, and weight loss maintenance follow-up statistics using these procedures are presented.

Arousal↗
PubMed1993

Prediction of protein secondary structures by a neural network.

We have studied the prediction of globular protein secondary structures by neural networks. Protein secondary structures are allocated to amino acid residues using Kabsch and Sander's dictionary of protein secondary structures and the neural network is taught the protein secondary structures. The input layer of the neural network allows sequences of residues including 20 amino acids, chain break, B, X and Z. We consider classifying secondary structures into groups of 3, 4 and 8. In each case, we calculate the percentage of correct predictions. We discuss the effect of overlearning on the protein secondary structure prediction. In addition, we include the application of a neural network with a modular architecture to prediction of protein secondary structures. We compare the results from neural networks with a modular architecture and with a simple three-layer structure.

Algorithms↗
PubMed1997

Stimulation over the human supplementary motor area interferes with the organization of future elements in complex motor sequences.

We used high-frequency repetitive transcranial magnetic stimulation (rTMS) to study the role of the mesial frontocentral cortex (including the supplementary motor area) in the organization of sequential finger movements of different complexity in humans. In 15 subjects, rTMS was randomly applied to the scalp overlying the region of the supplementary motor area and over other positions, including the contralateral primary motor cortex (hand area) during the performance of three overlearned finger sequences on an electronic piano. In all trials, rTMS (frequency 15-20 Hz) started 2 s after the first key press and lasted for approximately 2 s. All sequences were metronome-paced at 2 Hz and retrieved from memory. The 'simple' sequence consisted of 16 repeated index finger key presses, the 'scale' sequence of four times four sequential key presses of the little, ring, middle and index fingers, and the 'complex' sequence of a much less systematic and, therefore, more difficult series of 16 key presses. To measure the effects of rTMS interference with regional cortical function, we analysed rTMS-induced accuracy errors in the movement sequences. Stimulation over the supplementary motor area induced accuracy errors only in the complex sequence, while stimulation over the primary motor cortex induced errors in both the complex and scale sequences, and stimulation over other positions (e.g. F3, F4, FCz, P3, P4) did not interfere with sequence performance at all. Stimulation over the supplementary motor area interfered with the organization of subsequent elements in the complex sequence of movements, with error induction occurring approximately 1 s later than with stimulation over the primary motor cortex. Our findings are in keeping with recent results in non-human primates (Tanji J, Shima K. Nature, 1994; 371: 413-6) indicating a critical role of the supplementary motor area in the organization of forthcoming movements in complex motor sequences that are rehearsed from memory and fit into a precise timing plan.

Adult↗
PubMed1999

Functional coupling of human cortical sensorimotor areas during bimanual skill acquisition.

Bimanual co-ordination of skilled finger movements is a high-level capability of the human motor system and virtually always requires training. Little is known about the physiological processes underlying successful bimanual performance and skill acquisition. In the present study, we used task-related coherence (TRCoh) and task-related power (TRPow) analysis of multichannel surface EEG to investigate the functional coupling and regional activation of human sensorimotor regions during bimanual skill acquisition. We focused on changes in interhemispheric coupling associated with bimanual learning. TRCoh and TRPow were estimated during the fusion of two overlearned unimanual finger-tapping sequences into one novel bimanual sequence, before and after a 30-min training period in 18 normal volunteers. Control experiments included learning and repetition of complex and simple unimanual finger sequences. The main finding was a significant increase in interhemispheric TRCoh selectively in the early learning stage (P < 0.0001). Interhemispheric TRCoh was also present during the unimanual control tasks, but with lower magnitude, even if learning was involved. Training improved bimanual sequence performance (from 58.3+/-24.1 to 83.7+/-15.3% correct sequences). After training, interhemispheric (bimanual) TRCoh decreased again, thereby approaching levels similar to those in the unimanual controls. We propose that the initial increase in TRCoh reflects changes in interhemispheric communication that are specifically related to bimanual learning and may be relayed through the corpus callosum. The present data might also offer a neurophysiological explanation for the clinical observation that patients with lesions of the corpus callosum may show deficits in the acquisition of novel bimanual tasks but not necessarily in the execution of previously learned bimanual activities.

Adult↗
PubMed2002

Posterior parietal cortex is implicated in continuous switching between verbal fluency tasks: an fMRI study with clinical implications.

We investigated whether posterior parietal cortex controls attentional switching when the tasks involve neither spatial nor visual cognition. Normal volunteers were scanned using functional MRI (fMRI). In all conditions, subjects were required to covertly produce words in verbal fluency tasks. They did so at a rate of one every 2 s (with eyes closed) in response to an auditory beep. In the non-switching (NS) trials, subjects responded with a series of items from a prespecified semantic category (SC) (e.g. fruits or cars) and from overlearned sequences (OSs) (days of the week, months of the year or letters of the alphabet). Instructions as to which category items should be drawn from on a given run of trials were presented over fMRI-compatible earphones prior to each run. In the switching (S) trials, subjects produced a series of word triads from three SCs: for example, fruits, cars and furniture (e.g. pear, Mercedes, table.); and from three OSs: days of the week, months of the year and letters of the alphabet (e.g. Monday, January, A.). This design is factorial, with the factors verbal class (SC or OSs) and switching conditions (S or NS). Increases in neural activity (P < 0.05, corrected for multiple comparisons) were observed only in superior posterior parietal cortex bilaterally as a main effect of the S conditions compared with the NS conditions. When SC fluency was compared with OS fluency, significant activations were found in anterior cingulate cortex bilaterally, the left inferior frontal gyrus, the middle frontal gyrus bilaterally, frontal operculum bilaterally and in the cerebellar vermis. These results support the hypothesis that superior posterior parietal cortex is a supramodal area implicated in task switching, even when no visual or spatial component is implicated in the tasks. Task switching, frequently used to examine 'frontal' executive functions, may also be clinically relevant to the assessment of patients with superior posterior parietal lesions.

Adult↗
PubMed2002

Speech production: Wernicke, Broca and beyond.

We investigated the brain systems engaged during propositional speech (PrSp) and two forms of non- propositional speech (NPrSp): counting and reciting overlearned nursery rhymes. Bilateral cerebral and cerebellar regions were involved in the motor act of articulation, irrespective of the type of speech. Three additional, left-lateralized regions, adjacent to the Sylvian sulcus, were activated in common: the most posterior part of the supratemporal plane, the lateral part of the pars opercularis in the posterior inferior frontal gyrus and the anterior insula. Therefore, both NPrSp and PrSp were dependent on the same discrete subregions of the anatomically ill-defined areas of Wernicke and Broca. PrSp was also dependent on a predominantly left-lateralized neural system distributed between multi-modal and amodal regions in posterior inferior parietal, anterolateral and medial temporal and medial prefrontal cortex. The lateral prefrontal and paracingulate cortical activity observed in previous studies of cued word retrieval was not seen with either NPrSp or PrSp, demonstrating that normal brain- language representations cannot be inferred from explicit metalinguistic tasks. The evidence from this study indicates that normal communicative speech is dependent on a number of left hemisphere regions remote from the classic language areas of Wernicke and Broca. Destruction or disconnection of discrete left extrasylvian and perisylvian cortical regions, rather than the total extent of damage to perisylvian cortex, will account for the qualitative and quantitative differences in the impaired speech production observed in aphasic stroke patients.

Aphasia, Broca↗
PubMedDate not supplied

Perceptual and cognitive visual functions of parietal and temporal cortices in the cat.

We used reversible cooling deactivation to compare the functions of cortices lining the middle suprasylvian (MS) sulcus and forming the ventral portion of the posterior suprasylvian (vPS) gyrus. A battery of attentional, motion and mnemonic processing tasks were used and performance was examined during deactivation of each region. The results show a clear dissociation of functions. Deactivation of MS cortex resulted in profound deficits on a visual orienting task and on the discrimination of direction of motion, whereas deactivation of vPS cortex severely impaired both retention and learning of novel and overlearned object discriminations. In addition, deactivation of either MS or vPS cortex impaired discrimination of learned patterns when components of the patterns were in motion, whereas only deactivation of vPS cortex impaired the discrimination when all components were static. Together, these results show that a region of parietal cortex contributes to the processing of visual motion and to attentional processes, whereas a region of temporal cortex contributes to the learning and recognition of three-dimensional objects and two-dimensional patterns. This functional dissociation is linked to differences in underlying visual pathways, which have many features in common with the parietal and temporal visual processing streams previously identified in monkeys and humans. Furthermore, the broad similarity in neural operations carried out in parietal and temporal cortices of cats, monkeys and humans suggests the existence of a common plan for cortical processing machinery within mammals with well developed cerebral cortices.

Animals↗
PubMed2004

Suppressing versus releasing a habit: frequency-dependent effects of prefrontal transcranial magnetic stimulation.

When subjects are required to generate a random sequence of numbers they typically produce too many forward and backward 'counts' (e.g. 5-6, 4-3). This counting bias is interpreted as the consequence of an interference by overlearned tendencies to arrange numbers according to their natural order. Inhibition of such well-learned routines is known to rely on frontal lobe functioning. We examined differential effects of slow (1 Hz) and fast (10 Hz) repetitive transcranial magnetic stimulation (rTMS) over the left or right dorsolateral prefrontal cortex (DLPFC) on random number generation (RNG) performance. Eighteen healthy men performed an RNG task. Those subjects stimulated over the left DLPFC showed a frequency-dependent rTMS effect: counting bias was significantly reduced after the 1 Hz stimulation compared with baseline, but significantly exaggerated after the 10 Hz stimulation compared with 1 Hz stimulation. In contrast, the sequences of the subjects stimulated over the right DLPFC showed the well-known excess of counting in all conditions (i.e. baseline, 1 Hz and 10 Hz). These findings confirm the functional importance of specifically the left DLPFC in sequential response production and show, for the first time, that rTMS affects cognitive processing in a frequency-dependent manner.

Adult↗
PubMed2006

The effect of temporal asynchrony on the multisensory integration of letters and speech sounds.

Temporal proximity is a critical determinant for cross-modal integration by multisensory neurons. Information content may serve as an additional binding factor for more complex or less natural multisensory information. Letters and speech sounds, which form the basis of literacy acquisition, are not naturally related but associated through explicit learning. We investigated the relative importance of temporal proximity and information content on the integration of letters and speech sounds by manipulating both factors within the same functional magnetic resonance imaging (fMRI) design. The results reveal significant interactions between temporal proximity and content congruency in anterior and posterior auditory association cortex, indicating that temporal synchrony is critical for the integration of letters and speech sounds. The temporal profiles for multisensory integration in the auditory association cortex resemble those demonstrated for single multisensory neurons in different brain structures and animal species. This similarity suggests that basic neural integration rules apply to the binding of multisensory information that is not naturally related but overlearned during literacy acquisition. Furthermore, the present study shows the suitability of fMRI to study temporal aspects of multisensory neural processing.

Acoustic Stimulation↗
PubMedDate not supplied

Abnormalities of the nervous system in Lyme disease: response to antimicrobial therapy.

Objective measures of neurologic function were used to assess response to treatment in patients with late Lyme borreliosis. Neurophysiologic evidence of peripheral neuropathy was present in 64 of 137 patients tested. Measures of distal axon function (sensory amplitude and conduction velocity, motor terminal latency) were most affected. Repeat studies following 60 patients receiving antimicrobial therapy demonstrated significant improvement in these values. Before and after therapy 17 patients with late Lyme borreliosis and prominent subjective cognitive dysfunction underwent neuropsychologic tests of memory, conceptual ability, concentration, psychomotor function, overlearned intellectual abilities, and mood. Significant abnormalities were evident before treatment; all reversed with antimicrobial therapy. Many patients with this encephalopathy had specific abnormalities revealed by magnetic resonance imaging of the brain and had evidence of intrathecal synthesis of antibody to Borrelia. These findings indicate that late Lyme borreliosis commonly causes nervous system abnormalities that are reversible with appropriate antibiotic therapy.

Anti-Bacterial Agents↗
PubMed1992

A comparative analysis of functional status among Spanish- and English-speaking patients with dementia.

The assessment of functional capacity is regarded as an important part of a comprehensive diagnostic work-up for dementia. However, there is a paucity of data regarding comparative functional performance among different ethnic/cultural groups. In this study, we compared Spanish- and English-speaking dementia patients and normal controls on a comprehensive functional assessment battery administered within the clinical setting. Despite equivalent levels of cognitive impairment, Spanish-speaking dementia patients evidenced more difficulties on certain functional tasks relative to their English-speaking counterparts. On the other hand, Spanish- and English-speaking controls did not differ with regards to their functional performance. Results suggest that the extent of deterioration in specific functional subskills may be related to the degree to which they have been overlearned and practiced. Further, they indicate the potential utility of direct functional assessment in both Spanish- and English-speaking populations.

Activities of Daily Living↗
PubMed1993

Case report: profound neurobehavioral deficits in an oil field worker overcome by hydrogen sulfide.

A 24-year-old oil well tester was rendered semiconscious by hydrogen sulfide (H2S). He received oxygen and was hospitalized but released in 30 minutes. The next day, nausea, vomiting, diarrhea, and incontinence of urine and stool led to rehospitalization. These problems and leg shaking, dizziness, sweating, trouble sleeping, and nightmares prevented his return to work. A physical examination, chest x-ray, and pulmonary function tests were normal 39 months after the episode but vibration sense was diminished. Two choice visual reaction times were delayed. Balance was highly abnormal (5 to 6 cm/sec) with eyes closed. Blink reflex latency was slow (R-1 17.5 msec versus normal 14.3 msec). Numbers written on finger tips were not recognized. Verbal and visual recall were impaired but overlearned memory was intact. Cognitive functions measured by Culture Fair, block design, and digit symbol were impaired. Perceptual motor was slow. Scores for confusion, tension-anxiety, depression, and fatigue were elevated and vigor was reduced. Forty-nine months after exposure his reaction time, sway speed, and color vision had not improved. His recall and his cognitive, constructional, and psychomotor speeds had improved but remained abnormal. These deficits are most likely due to H2S. Similar testing of other survivors is recommended.

Accidents, Occupational↗
PubMed1992

Left hemisphere preponderance in trajectorial learning.

The present study examines the organisational principle of a trajectorial storage mechanism for isochronically controlled overlearned movements. 48 right-handed subjects were trained on new ideograms at five different sizes. After the trajectory had been overtrained with one hand, learning transfer to the contralateral hand was analysed. Results indicate a significant transfer of trajectorial information after training with the right hand towards the left hand which points to a preponderance of the dominant left hemisphere in generalizing storage of learned trajectories to either upper extremity. The trajectorial storage system has clear geometrical restraints.

Female↗
PubMed2002

MEG study of long-term cortical reorganization of sensorimotor areas with respect to using chopsticks.

The movements required to use chopsticks are overlearned and routine in Asians. Most non-Asians, on the other hand, typically have difficulty performing this unfamiliar manual activity, and have to focus their attention on the movements required to use chopsticks adequately. Using magnetoencephalography (MEG) we compared the cortical activation of highly trained Asian chopstick users to the activation of Europeans who only occasionally used chopsticks, while they performed the same tasks with chopsticks or a control task of simple tapping of the same fingers. The data were analyzed using the new method of synthetic aperture magnetometry (SAM). In Europeans there was a significantly higher ratio of spectral power in the higher gamma frequency band (60-80 Hz) over the sensorimotor area compared to the Asian subjects. From these results we conclude that the high gamma band activity in the sensorimotor area may reflect focused attention and functional reorganization of the cortical network with respect to sensorimotor experience.

Adult↗
PubMed1980

Disability and intellectual function in multiple sclerosis patients.

Forty-eight multiple sclerosis patients were rated on the Kurtzke Disability Status Examination and tested on the Wechsler Adult Intelligence Scale. Their disability status scores, ranging from 1 to 9, with a mean of 3.98, correlated significantly only with duration of illness (r = .33, significant at the.05 level). Severity of disability was not significantly correlated with age of patient, age at onset of multiple sclerosis symptoms, Verbal IQ, Performance IQ, or Full Scale IQ. Wechsler Adult Intelligence Scale mean subtest scores ranged from average to bright normal. Scores on Performance subtests with a large motor component were lower than on Verbal subtests measuring verbal overlearned information, abstract reasoning, and vocabulary.

Adolescent↗
PubMed1996

Persistent neurotoxicity from a battery fire: is cadmium the culprit?

Two train conductors had chest tightness, painful breathing, muscle cramps, and nausea after fighting a fire in a battery box under a passenger coach. Shortly thereafter, they became anosmic and had excessive fatigue, persistent headaches, sleep disturbances, irritability, unstable moods, and hypertension. Urinary cadmium and nickel levels were elevated. Neurobehavioral testing showed, in comparison to referents, prolonged reaction times, abnormal balance, prolonged blink reflex latency, severely constricted visual fields, and decreased vibration sense. Test scores showed that immediate verbal and visual recall were normal but delayed recall was reduced. Scores on overlearned information were normal. Tests measuring dexterity, coordination, decision making, and peripheral sensation and discrimination revealed abnormalities. Repeat testing 6 and 12 months after exposure showed persistent abnormalities. Cadmium and vinyl chloride are the most plausible causes of the neurotoxicity, but fumes from the fire may have contained other neurotoxic chemicals.

Accidents, Occupational↗
PubMed2004

A primate model of anterograde and retrograde amnesia produced by convulsive treatment.

A nonhuman primate model of the key cognitive effects of convulsive treatment was developed and tested. Rhesus macaques were trained on 3 tasks: a long-term memory task that required selection of a constant target from a background of distracters, an anterograde task that involved learning a new target each day against a variable number of distracters, and a task that assessed learning and memory for new and previously trained 3-item serial lists. This battery samples a range of cognitive functions, including orientation, working memory, retrograde amnesia for temporally graded stimuli, and anterograde amnesia. Using a within-subject, sham-controlled design, the amnestic effects of electroconvulsive shock (ECS) were evaluated in 2 monkeys. Significant effects of the interventions (sham and ECS) were seen on all tasks. The degree of impairment varied across tasks and as a function of task difficulty. ECS did not impair accuracy on the less difficult tasks (memory for an overlearned item and acquisition of a new item) but did increase the amount of time required to complete the tasks, consistent with a period of disorientation acutely after the intervention. This effect was progressive across the treatments. ECS impaired the acquisition and memory of new lists compatible with an anterograde memory deficit, whereas recall for old lists was relatively spared. This study developed and validated a cognitive battery to assess amnesia in nonhuman primates, providing new experimental paradigms for evaluating the cognitive effects of convulsive treatment.

Amnesia, Anterograde↗