Effects of feedback from active and passive body parts on spatial and temporal parameters in sensorimotor synchronization

Previous research on sensorimotor synchronization has manipulated the somatosensory information received from the tapping finger to investigate how feedback from an active effector affects temporal coordination. The current study explored the role of feedback from passive body parts in the regulation of spatiotemporal motor control parameters by employing a task that required finger tapping on one’s own skin at anatomical locations of varying tactile sensitivity. A motion capture system recorded participants’ movements as they synchronized with an auditory pacing signal by tapping with the right index finger on either their left index fingertip (Finger/Finger) or forearm (Finger/Forearm). Results indicated that tap timing was more variable, and movement amplitude was larger and more variable, when tapping on the finger than when tapping on the less sensitive forearm. Finger/Finger tapping may be impaired relative to Finger/Forearm tapping due to ambiguity arising through overlap in neural activity associated with tactile feedback from the active and the passive limb in the former. To compensate, the control system may strengthen the assignment of tap-related feedback to the active finger by generating correlated noise in movement kinematics and tap dynamics.     

Language localization and variability

Language localization data from 11 neurosurgical patients undergoing cortical resection for medically intractable focal epilepsy were obtained by mapping with bipolar electrical stimulation at current levels below sensory and after-discharge thresholds, during an object-naming task. The topographical extent of language cortex in an individual subject can be wider than that proposed in the classic maps. Within this zone, language is discretely localized, with different sites variably committed to language as measured by the naming function. The naming data from the left cortex of eight patients, all left-brain-dominant, were pooled to determine the variability within the primary language zone. Only a narrow band of posterior, inferior frontal lobe, immediately anterior to motor strip, showed involvement in all of the patients in whom it was sampled. This is a motor speech area; it constitutes only a small portion of the frontal language area. Other infero-frontal, parietal, and postero-temporal sites showed considerable variability, with naming involvement in only 50–80% of the patients sampled. There is a suggestion that some of these patterns of language localization may correlate with poorer verbal abilities. Data were also obtained on language localization in the left insula in a patient who was left-hemisphere-dominant for language. Mapping of the right hemisphere in a left-brain-dominant patient demonstrated no naming function. Mapping of the right hemisphere in one and the left hemisphere in another patient, both of whom were right-hemisphere-dominant for language, suggests more diffuse language representation with right hemisphere dominance.     

Temperature self-regulation and relaxation with migraine patients and normals

Ten migraine headache subjects and 10 non-migraine subjects were divided equally into two groups: a progressive relaxation group and a finger temperature biofeedback group. Finger temperature, temporal artery pulse amplitude and forehead blood flow were monitored for all subjects during two baseline and six treatment sessions.

The biofeedback group achieved greater (albeit low magnitude) increases in finger temperature than the relaxation group, but no improvement in headache activity was obtained. However the relaxation group improved significantly in terms of headache intensity.

There was no significant difference in the ability to achieve finger temperature control, nor in stability point temperatures, between the migraine and non-migraine subjects.

No systematic relationship was found between finger temperature, forehead blood volume and temporal artery pulse amplitude. Possible mechanisms of the therapeutic effects of finger temperature training are examined in the light of these results.     

Organization of short-term verbal memory in language areas of human cortex: Evidence from electrical stimulation

Short-term verbal memory (STVM) performance was measured during electrical stimulation of human left frontal-parietal-temporal cortex, at craniotomy under local anesthesia for the treatment of medically intractable epilepsy. The areas of cortex where stimulation alters language, as measured by object naming, are separate but adjacent to the areas where stimulation alters STVM. There are differential effects of stimulation during input, storage, and output phases of STVM at different cortical sites. These suggest that cortex adjacent to the posterior language area is a site of storage of STVM, while cortex adjacent to anterior language area is involved in retrieval from STVM.     

Language after temporal or frontal lobe surgery in children with epilepsy

The purpose of this study was to compare language function in children undergoing temporal or frontal lobe surgery to control intractable epilepsy. Language measures (expressive vocabulary, receptive vocabulary, comprehension, reading, spelling, phonemic fluency, and category fluency) were administered to 9 children with frontal lobe epilepsy (mean age: 10.8 +/- 2.7 years) and 10 children with temporal lobe epilepsy (11.5 +/- 2.6 years). The results indicate that no differences exist, in language function, before and after surgery between children with frontal and temporal lobe epilepsy (all p > or = .05). Children with left hemisphere lesions had significantly lower scores than those with right on category fluency and comprehension, but laterality effects were not seen on the other measures. In both groups, language function was not significantly affected by surgery.     

Vibrotactile masking: Some spatial and temporal aspects

Threshold elevations (TE) were determined for three Os at a test site on the left thigh with a masker placed singly at each of 10 widespread loei on the trunk. Although lateral changes in masker placement did not produce a significant alteration in TE (p> .10), there was a systematic decrease in TE with longitudinal separation between masker and test sites on the body. Appropriate manipulations of the time interval between masker and test signals were found effective in offsetting these decreases. It appeared that longitudinal separations were differentially affecting temporal delays by producing unequal neural distances from the test and masker sites to the CNS. There were, however, some spatial changes that could not be accounted for by temporal offsets. Thresholds at a finger test site were significantly less elevated (p< .01) by contralateral placement of maskers than by ipsilateral placement, and the particular test site chosen for threshold determinations, either index finger or thigh, determined the amount of TE.     

Cerebral excitation profiles in language processing: The photic probe paradigm

A photic probe paradigm was developed in order to assess the cerebral excitation patterns corresponding to acoustic and linguistic operations independently of specific signal parameters. Average Evoked Potentials (AEPs) to a photic stimulus were recorded at the anterior temporal and posterior regions of both hemispheres of subjects engaged in acoustic, phonetic, and semantic processing of verbal material. Patterns of attenuation and enhancement of the probe AEP amplitudes were observed over the left and right hemispheres, respectively, with the magnitude of change varying reliably as a function of processing task. The implications of these findings for models of cerebral specialization for language are discussed.     

The functional anatomy of word comprehension and production

This review describes the functional anatomy of word comprehension and production. Data from functional neuroimaging studies of normal subjects are used to determine the distributed set of brain regions that are engaged during particular language tasks and data from studies of patients with neurological damage are used to determine which of these regions are necessary for task performance. This combination of techniques indicates that the left inferior temporal and left posterior inferior parietal cortices are required for accessing semantic knowledge; the left posterior basal temporal lobe and the left frontal operculum are required for translating semantics into phonological output and the left anterior inferior parietal cortex is required for translating orthography to phonology. Further studies are required to establish the specific functions of the different regions and how these functions interact to provide our sophisticated language system.     

手指的感知、运动以及数量表征对数字认知的促进作用

手指是儿童在习得数字符号之前最常使用的表征数量的工具,大量研究都表明手指在数字认知中具有促进作用。但是,目前仍不清楚手指在数字认知中的作用机制。综述从手指感知、手指运动以及手指数量表征三个方面总结了手指在数字认知中所起的作用。手指感知可能通过影响儿童的数量表征能力间接地影响其它数学能力;与表征量有关的手指运动可能促进了数量大小的加工。关于手指数量表征在数字认知中的作用存在两种有争议的观点：一种认为手指数量表征促进了儿童由非符号数量表征向符号数量表征的转化;另一种认为手指数量表征可能是一种数量语义表征方式。未来应该在发展、作用机制、性别差异等方向继续开展研究,进一步探讨手指在数字认知中所起的作用。     

Pure agraphia and Gerstmann's syndrome as a visuospatial-language dissociation: an experimental case study

A right-handed man suffered a left parieto-occipital cerebral infarction, causing agraphia with Gerstmann's syndrome but without major aphasia, alexia, or apraxia. Oral spelling was superior to written spelling. Experiments were performed involving (1) analysis of errors in writing, (2) tasks of visual imagery, and (3) identifying letters drawn without leaving a visual trace. The results suggest that the agraphia and Gerstmann's syndrome are due to a dissociation of language skills and visuospatial skills caused by a dominant parieto-occipital lesion.     

Bilateral language: Is the left hemisphere still dominant?

A 13-year-old left-handed boy with a left fronto-parietal vascular malformation evidenced bilateral symmetrical language representation at intracarotid amytal testing. Surgical resection of the parietal motor and frontal premotor area (sparing classical perisylvian language regions) for seizure control resulted in an acute aphasia. Language deficits were still apparent 3 months and to a lesser degree 1 year after surgery. This suggests that when language is bilateral and symmetrical, the left hemisphere may still be dominant or both hemispheres may be necessary to sustain full language competence. Explanations for atypical language localization within the left hemisphere are also discussed.     

First-Pass versus Second-Pass Parsing Processes in a Wernicke''s and a Broca''s Aphasic: Electrophysiological Evidence for a Double Dissociation

The present paper is a first attempt to integrate the classical brain lesion behavioral impairment approach of functional neuroanatomy and the electrophysiological brain mapping approach in the domain of syntactic processing. In a group of normal age-matched controls we identified three electrophysiological components previously observed in correlation with language comprehension processes: an early left anterior negativity normally seen in correlation with syntactic first-pass parsing processes (ELAN), a centroparietal negativity seen in correlation with processes of lexical-semantic integration (N400), and a late centroparietal positivity observed in correlation with secondary syntactic processes of reanalysis and repair (P600). The early left anterior negativity was absent in a patient with an extended lesion in the anterior part of the left hemisphere sparing the temporal lobe, although the late centroparietal positivity and the centroparietal N400 were present. In a patient with a left temporal-parietal lesion the early left anterior negativity was found to be present, whereas the N400 component was absent. These findings suggest that first-pass parsing and secondary processes are subserved by distinct brain systems.     

Memory deficits during electrical stimulation of the speech cortex in conscious man

Cerebral zones supporting language and recent memory were mapped by electrical stimulation during neurosurgical treatment of epileptic patients. Stimulation of sites within the left posterior temporo-parietal cortex produced transient dysphasia. Continued stimulation of this cortical region also produced a retrograde type of verbal memory disorder, indicating a failure in the mechanism responsible for retrieval of stored information. In contrast, stimulation of the anterior temporal neocortex did not produce anomia and, instead, resulted in an anterograde memory loss, apparently caused by a defect in the verbal storage mechanism. Comparable stimulation of homologous areas on the right hemisphere did not interfere with object naming or immediate verbal recall.     

Dissociated naming and locating of body parts after left anterior temporal lobe resection: An experimental case study

After resection of the left anterior temporal lobe, a 17-year-old girl showed a dissociation of the verbal and nonverbal elements of lateral body orientation. She could identify body parts and body side on herself or on a confronting person, but was impaired in producing and understanding body part names. The verbal and topographic components of body orientation are neurally separable since they can be differently affected by cerebral damage.     

PET activation studies comparing two speech tasks widely used in surgical mapping

"Automatic" speech, especially counting, is frequently preserved in aphasia, even when word production is severely impaired. Although brain sites and processes for automatic speech are not well understood, counting is frequently used to elicit fluent speech during preoperative and intraoperative cortical mapping for language. Obtaining both behavioral and functional brain imaging measures, this study compared counting with a word production task (generation of animal names), including non-verbal vocalizations and quiet rest as control states, in normal and aphasic subjects. Behavioral data indicated that normal and aphasic groups did not differ in counting or non-verbal vocalizations, but did differ significantly in word production ("naming" animals). Functional brain imaging results on normal subjects using partial least squares analysis of PET rCBF images revealed three significant latent variables (LVs): one for naming and vocalizing, identifying bilateral anterior areas, with left predominating over right; a second LV for naming, identifying left and right frontal and temporal areas. For the third, only marginally significant LV, which was associated with automatic speech alone (counting), right and subcortical sites predominated. For patients, two LVs emerged, identified with naming and vocalization, and corresponding to a variety of cerebral sites; the analysis failed to find a specific latent variable for counting. A comparison between group data for normal subjects and patients suggested that the naming, counting, and vocalization tasks were performed differently by the two groups. These results suggest that word generation as a verbal task is more likely to elicit activity in classical language areas than counting. Further studies are suggested to better understand differences between neurological substrates for non-propositional and automatic speech.     

Syntactic structure building in the anterior temporal lobe during natural story listening

The neural basis of syntax is a matter of substantial debate. In particular, the inferior frontal gyrus (IFG), or Broca’s area, has been prominently linked to syntactic processing, but the anterior temporal lobe has been reported to be activated instead of IFG when manipulating the presence of syntactic structure. These findings are difficult to reconcile because they rely on different laboratory tasks which tap into distinct computations, and may only indirectly relate to natural sentence processing. Here we assessed neural correlates of syntactic structure building in natural language comprehension, free from artificial task demands. Subjects passively listened to Alice in Wonderland during functional magnetic resonance imaging and we correlated brain activity with a word-by-word measure of the amount syntactic structure analyzed. Syntactic structure building correlated with activity in the left anterior temporal lobe, but there was no evidence for a correlation between syntactic structure building and activity in inferior frontal areas. Our results suggest that the anterior temporal lobe computes syntactic structure under natural conditions.     

Finger localization and finger praxis

The relations between finger localization and various types of finger praxis were assessed by estimates of the inter-correlations among the performance of 100 six-year-old children. Finger localization was related significantly to those types of finger praxis which involve movements of the individual fingers with respect to each other. Right-left discrimination was related to finger localization, but not to the measures of finger praxis.

The findings are interpreted in terms of the construct of the finger schema, which can be viewed as a determinant of performance in both the localization and praxis tasks. This construct can also serve as an explanation of the observed concurrence of finger agnosia and finger apraxia as a consequence of cerebral disease.     

Semantic dementia and persisting Wernicke's aphasia: linguistic and anatomical profiles

Few studies have directly compared the clinical and anatomical characteristics of patients with progressive aphasia to those of patients with aphasia caused by stroke. In the current study we examined fluent forms of aphasia in these two groups, specifically semantic dementia (SD) and persisting Wernicke’s aphasia (WA) due to stroke. We compared 10 patients with SD to 10 age- and education-matched patients with WA in three language domains: language comprehension (single words and sentences), spontaneous speech and visual semantics. Neuroanatomical involvement was analyzed using disease-specific image analysis techniques: voxel-based morphometry (VBM) for patients with SD and overlays of lesion digitized lesion reconstructions in patients with WA. Patients with SD and WA were both impaired on tasks that involved visual semantics, but patients with SD were less impaired in spontaneous speech and sentence comprehension. The anatomical findings showed that different regions were most affected in the two disorders: the left anterior temporal lobe in SD and the left posterior middle temporal gyrus in chronic WA. This study highlights that the two syndromes classically associated with language comprehension deficits in aphasia due to stroke and neurodegenerative disease are clinically distinct, most likely due to distinct distributions of damage in the temporal lobe.     

Dissociation of recognition memory components following temporal lobe lesions

It has been proposed that recognition decisions are based on contextual retrieval of specific trace information, in addition to an assessment of item strength. The retrieval component is maximal after a single presentation, whereas the strength component increases with multiple repetition. We report that unilateral anterior temporal lobectomy (ATL) in the language dominant (left) hemisphere impairs initial recognition accuracy without affecting the rate at which repetition improves performance. The implication that the temporal lobe contributes to retrieval rather than strength during recognition is supported by simultaneous event-related potential (ERP) recordings. In normal subjects, the large ERP difference between repeated and nonrepeated words does not increase with increasing study and is associated with contextual integration in other tasks. Thus, the lack of a repetition-induced ERP difference after left-ATL reported here provides converging evidence for a critical role of the temporal lobe in contextual retrieval during recognition.     

Comparison between Oral and Written Spelling in Alzheimer's Disease

Written and oral spelling were compared in 33 patients with Alzheimer's disease (AD) and 25 control subjects. AD patients had poorer spelling results which were influenced by orthographic difficulty and word frequency, but not by grammatical word class. Lexical spelling was also more deteriorated than phonological spelling. Moreover, oral spelling was more impaired than written spelling in AD patients, whereas no difference was present between oral and written spelling of controls. Analysis of spelling errors showed that, for controls, errors were predominantly phonologically accurate in both spelling tasks. Significantly, AD patients produced more phonologically accurate than inaccurate errors in written spelling, whereas these errors did not differ in oral spelling. In contrast to controls who produced more constant than variable responses in oral and written spelling, AD patients made more variable responses (words correctly spelled in one task but incorrectly in the other) and they showed many instances of variable errors (different misspellings from one spelling task to the other). Two stepwise regression procedures showed that written misspellings were specifically correlated with language impairment, whereas oral spelling errors were correlated with attentional and language disorders. These results suggest that AD increases the attentional demands of oral spelling process as compared to written spelling. This dissociation argues, either for a unique Graphemic Buffer in which oral spelling requires more attentional resources than written spelling or for the hypothesis of separate buffers for oral and written spelling.