Effective connectivity hierarchically links temporoparietal and frontal areas of the auditory dorsal stream with the motor cortex lip area during speech perception

A left-hemispheric cortico-cortical network involving areas of the temporoparietal junction (Tpj) and the posterior inferior frontal gyrus (pIFG) is thought to support sensorimotor integration of speech perception into articulatory motor activation, but how this network links with the lip area of the primary motor cortex (M1) during speech perception is unclear. Using paired-coil focal transcranial magnetic stimulation (TMS) in healthy subjects, we demonstrate that Tpj → M1 and pIFG → M1 effective connectivity increased when listening to speech compared to white noise. A virtual lesion induced by continuous theta-burst TMS (cTBS) of the pIFG abolished the task-dependent increase in pIFG → M1 but not Tpj → M1 effective connectivity during speech perception, whereas cTBS of Tpj abolished the task-dependent increase of both effective connectivities. We conclude that speech perception enhances effective connectivity between areas of the auditory dorsal stream and M1. Tpj is situated at a hierarchically high level, integrating speech perception into motor activation through the pIFG.     

Transient beneficial effects of excitatory theta burst stimulation in a patient with phonological agraphia after left supramarginal gyrus infarction

We report a patient showing isolated phonological agraphia after an ischemic stroke involving the left supramarginal gyrus (SMG). In this patient, we investigated the effects of focal repetitive transcranial magnetic stimulation (rTMS) given as theta burst stimulation (TBS) over the left SMG, corresponding to the Brodmann area (BA) 40. The patient and ten control subjects performed a dictational words and nonwords writing task before, and 5 and 30 min after they received excitatory intermittent TBS (iTBS) over the left BA 40, the right hemisphere homologous to BA 40, the Wernicke’s area, or the primary visual cortex.ITBS over the left SMG lead to a brief facilitation of phonological non-words writing to dictation. This case study report illustrates that rTMS is able to influence, among other language functions, the phonological loading processes during the written language production in stroke patients.     

Two-matrix orthogonal rotation procedures

Examples are presented in which it is either desirable or necessary to transform two sets of orthogonal axes to simple structure positions by means of the same transformation matrix. A solution is then outlined which represents a two-matrix extension of the general orthomax orthogonal rotation criterion. In certain circumstances, oblique two-matrix solutions are possible using the procedure outlined and the Harris-Kaiser [1964] logic. Finally, an illustrative example is presented in which the preceding technique is applied in the context of an inter-battery factor analysis.The work reported herein was supported by Grant S72-1886 from the Canada Council. The author acknowledges the helpful contributions of Nancy Reid and Lawrence Ward to parts of this paper.     

Linear structural equations with latent variables

An interdependent multivariate linear relations model based on manifest, measured variables as well as unmeasured and unmeasurable latent variables is developed. The latent variables include primary or residual common factors of any order as well as unique factors. The model has a simpler parametric structure than previous models, but it is designed to accommodate a wider range of applications via its structural equations, mean structure, covariance structure, and constraints on parameters. The parameters of the model may be estimated by gradient and quasi-Newton methods, or a Gauss-Newton algorithm that obtains least-squares, generalized least-squares, or maximum likelihood estimates. Large sample standard errors and goodness of fit tests are provided. The approach is illustrated by a test theory model and a longitudinal study of intelligence.This investigation was supported in part by a Research Scientist Development Award (KO2-DA00017) and a research grant (DA01070) from the U. S. Public Health Service.     

Principal component analysis of three-mode data by means of alternating least squares algorithms

A new method to estimate the parameters of Tucker's three-mode principal component model is discussed, and the convergence properties of the alternating least squares algorithm to solve the estimation problem are considered. A special case of the general Tucker model, in which the principal component analysis is only performed over two of the three modes is briefly outlined as well. The Miller & Nicely data on the confusion of English consonants are used to illustrate the programs TUCKALS3 and TUCKALS2 which incorporate the algorithms for the two models described.     

Behavioral and dimensional contrast in rats.

Rats pressed a nose key for brain stimulation reinforcement presented on a fixed-interval schedule. Stimuli were drawn at random from a continuum of 12 white noise intensities in the range 62-95 decibels, spaced in 3 decibel steps. Experiment 1 varied the number of stimuli and the reinforcement contingencies associated with them. In Condition I (baseline) all stimuli signaled reinforcement; in Conditions II and III stimuli from one half of the continuum signaled reinforcement and those from the other half, extinction. However, in Condition II the 6 stimuli from the middle of the continuum were omitted. Experiment 2 held constant the number of stimuli and varied their spacing. In Condition I, each of 6 sounds signaled reinforcement. In Conditions II and II, three stimuli from one half of the continuum signaled reinforcement and three from the other half, extinction. However, in Condition II the stimuli were near the extremes of the continuum (Stimuli 1, 3, 4, 9, 10, 12). Condition III replaced Stimulus 3 with Stimulus 6 and Stimulus 10 with Stimulus 7. Behavioral contrast was seen in an increase over baseline in response rate to the stimuli associated with the constant schedule component when the variable component was changed to extinction. Dimensional contrast was seen in a further elevation of rate to intermediate positive stimulus values when stimuli were added to the border region between positive and negative values.     

ACQUISITION OF EXPRESSIVE SIGNING BY AUTISTIC CHILDREN: AN EVALUATION OF THE RELATIVE EFFECTS OF SIMULTANEOUS COMMUNICATION AND SIGN-ALONE TRAINING

Two methods of training autistic children to use manual signs were compared. Two children, one mute and one capable of some verbal imitation, were taught to use signs as expressive labels for pictures of objects. Using an alternating treatments design, speed of sign acquisition was compared across two training conditions in which signs were presented either accompanied by, or without, the corresponding verbal label. In both conditions, the training procedure incorporated reinforcement, modeling, prompting, fading, and stimulus rotation. The efficacy of training in both treatment conditions was demonstrated by the use of a multiple baseline control across signs, but no clear differences in acquisition speed across conditions were apparent. Posttests conducted to assess stimulus control of signing, and learning of verbal labels when these were present in training, showed that the behavior of the imitative, but not the mute, child was controlled by the verbal stimuli. The implications of the results both for understanding deficits characteristic of autistic children and for developing appropriate language training procedures are discussed.     

Increased regional cerebral glucose metabolism and semantic memory performance in Alzheimer's disease: A pilot double blind transdermal nicotine positron emission tomography study

Nicotinic receptor dysfunction and impaired semantic memory occur early in Alzheimer's disease patients (AD). Previous research implied that nicotine's ability to enhance alertness, arousal, and cognition in a number of nonclinical populations was a function of its ability to stimulate CNS nicotinic cholinergic receptors. In this study it was hypothesized that transdermal administration of nicotine would increase both regional cerebral glucose metabolism (rCMRglc) and semantic memory (as assessed by verbal fluency). Two mild AD and two elderly controls underwent positron emission tomography scanning during a double blind nicotinic agonist verbal fluency challenge procedure. rCMRglc increases occurred in both AD patients, but not controls. In the two AD patients, verbal fluency scores increased by an average of 17%. One elderly control's verbal fluency increased, and the other decreased. These findings suggest that nicotine's effect on metabolism and verbal fluency is due to its ability to stimulate the cholinergic system.     

Interference of Sentence and Picture Contexts on Learning Prepositions

The effects of extra stimulus cues, such as pictures and sentences, on learning of preposition words were examined in two experiments. A one-way repeated-measures design was applied in the study. The results show that both sentences and pictures interfered with and blocked the learning of these context-dependent words in the simultaneous presentations. The superiority of feedback presentations over simultaneous presentations indicate that feedback techniques neutralize the blocking effect. More interestingly, however, the prepositions were learned more quickly in the absence of any context cues and this suggested that it is better to teach basic preposition words either by the presentation of them alone or if extra stimulus cues are to be used they should be presented as feedback.     

A model-based standardization approach that separates true bias/DIF from group ability differences and detects test bias/DTF as well as item bias/DIF

A model-based modification (SIBTEST) of the standardization index based upon a multidimensional IRT bias modeling approach is presented that detects and estimates DIF or item bias simultaneously for several items. A distinction between DIF and bias is proposed. SIBTEST detects bias/DIF without the usual Type 1 error inflation due to group target ability differences. In simulations, SIBTEST performs comparably to Mantel-Haenszel for the one item case. SIBTEST investigates bias/DIF for several items at the test score level (multiple item DIF called differential test functioning: DTF), thereby allowing the study of test bias/DIF, in particular bias/DIF amplification or cancellation and the cognitive bases for bias/DIF.This research was partially supported by Office of Naval Research Cognitive and Neural Sciences Grant N0014-90-J-1940, 4421-548 and National Science Foundation Mathematics Grant NSF-DMS-91-01436. The research reported here is collaborative in every respect and the order of authorship is alphabetical. The assistance of Hsin-hung Li and Louis Roussos in conducting the simulation studies was of great help. Discussions with Terry Ackerman, Paul Holland, and Louis Roussos were very helpful.