Preattentive processing of spectral, temporal, and structural characteristics of acoustic regularities: A mismatch negativity study

Objective.Patients with hypertension show deficits in cognitive function. However, the neural mechanisms underlying the preattentive information processing in hypertensive patients are poorly understood. We seek to investigate whether hypertensive patients have impairments in preattentive information processing.Methods.We compared visual mismatch negativity (vMMN) between 15 hypertensive patients and 15 age-matched healthy controls, which was elicited by the change of visual duration randomly presented in both peripheral visual fields. In addition, the global cognitive function for all participants was assessed with Mini-Mental State Examination (MMSE).Results.The vMMN in deviant-standard comparison was observed at occipital-temporal regions. Compared with normal healthy controls, the amplitude of vMMN was significantly decreased in hypertensive patients (P<0.05). Meanwhile, the vMMN peak latency was delayed in the hypertensive group (P<0.05). However, the MMSE scores of patients with hypertension were not significantly different from those of controls (P>0.05), and there was no significant correlation between the mean amplitude of vMMN and SBP, DBP, and MMSE in hypertensive individuals, respectively.Conclusions.These data indicate dysfunction of automatically change detection processing in patients with hypertension. Moreover, the changes of vMMN provide a more objective and reliable assessment for cognitive impairment in hypertensive patients.

Download Full-text

Brain Processing (Auditory Event-Related Potential) of Stressed Versus Unstressed Words in Thai Speech

Perceptual and Motor Skills ◽

10.1177/0031512518794107 ◽

2018 ◽

Vol 125 (6) ◽

pp. 995-1010

Author(s):

Kittipun Arunphalungsanti ◽

Chailerd Pichitpornchai

Keyword(s):

Mismatch Negativity ◽

Brain Regions ◽

Event Related Potential ◽

Word Perception ◽

Word Condition ◽

Auditory Event ◽

Preattentive Processing ◽

Thai Language ◽

Central Brain ◽

Brain Processing

This study investigated the effect of the stressed word in Thai language on auditory event-related potential (aERP) in unattended conditions. We presented 30 healthy participants with monosyllabic Thai words consisting of either stressed or unstressed words. We instructed them not to attend to the sound stimuli, but rather to watch and memorize the contents of a silent natural documentary without subtitles. The two listening conditions consisted of 20% deviant stimuli (70 stressed and 70 unstressed words, respectively) and 80% standard stimuli (other 280 unstressed words) presented pseudorandomly and binaurally via a pair of earphones. Participants’ aERPs from the two conditions were evaluated by the mismatch negativity (MMN) component of aERP. The mismatch negativity amplitudes in the stressed word condition were significantly higher than those in the unstressed word condition, especially in frontal and left fronto-central brain areas. Therefore, these data show the role of the frontal and left fronto-central brain regions in auditory preattentive processing of stressed word perception among native Thai speakers. This is the first study demonstration that stressed meaningful monosyllable words in tonal language facilitate word perception in this preattentive stage. This result has implications for developing clinical tests evaluating preattentive speech perception.

Download Full-text

Preattentive Processing Abnormalities in Chronic Pain: Neurophysiological Evidence from Mismatch Negativity

Pain Medicine ◽

10.1111/j.1526-4637.2011.01097.x ◽

2011 ◽

Vol 12 (5) ◽

pp. 773-781 ◽

Cited By ~ 3

Author(s):

Shuqiao Yao ◽

Xianhua Liu ◽

Wenhui Yang ◽

Xiang Wang

Keyword(s):

Chronic Pain ◽

Mismatch Negativity ◽

Preattentive Processing

Download Full-text

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100055904 ◽

1982 ◽

Vol 40 ◽

pp. 722-723 ◽

Cited By ~ 1

Author(s):

R. Gronsky

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

High Resolution ◽

Computer Simulations ◽

Structural Characteristics ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Download Full-text

SEM analysis of the change in the reaction rates with deposit structures in the copper-iron cementation system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109422 ◽

1978 ◽

Vol 36 (1) ◽

pp. 456-457

Author(s):

V. Annamalai ◽

L.E. Murr

Keyword(s):

Structural Characteristics ◽

Secondary Electron Emission ◽

Copper Deposit ◽

Reaction Rates ◽

Sem Analysis ◽

Experimental Conditions ◽

Major Drawback ◽

Emission Mode ◽

Scrap Iron ◽

Image Position

Economical recovery of copper metal from leach liquors has been carried out by the simple process of cementing copper onto a suitable substrate metal, such as scrap-iron, since the 16th century. The process has, however, a major drawback of consuming more iron than stoichiometrically needed by the reaction.Therefore, many research groups started looking into the process more closely. Though it is accepted that the structural characteristics of the resultant copper deposit cause changes in reaction rates for various experimental conditions, not many systems have been systematically investigated. This paper examines the deposit structures and the kinetic data, and explains the correlations between them.A simple cementation cell along with rotating discs of pure iron (99.9%) were employed in this study to obtain the kinetic results The resultant copper deposits were studied in a Hitachi Perkin-Elmer HHS-2R scanning electron microscope operated at 25kV in the secondary electron emission mode.

Download Full-text

Use of 2½ D imaging in analysis of NiTi martensite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110192 ◽

1978 ◽

Vol 36 (1) ◽

pp. 610-611

Author(s):

G. M. Michal

Keyword(s):

Memory Effect ◽

Monoclinic Phase ◽

Reaction Path ◽

Structural Characteristics ◽

Salient Feature ◽

Martensite Phase ◽

Orientation Relationships ◽

Low Symmetry ◽

Hydride Phases ◽

Unusual Shape

Several TEM investigations have attempted to correlate the structural characteristics to the unusual shape memory effect in NiTi, the consensus being the essence of the memory effect is ostensible manifest in the structure of NiTi transforming martensitic- ally from a B2 ordered lattice to a low temperature monoclinic phase. Commensurate with the low symmetry of the martensite phase, many variants may form from the B2 lattice explaining the very complex transformed microstructure. The microstructure may also be complicated by the enhanced formation of oxide or hydride phases and precipitation of intermetallic compounds by electron beam exposure. Variants are typically found in selfaccommodation groups with members of a group internally twinned and the twins themselves are often observed to be internally twinned. Often the most salient feature of a group of variants is their close clustering around a given orientation. Analysis of such orientation relationships may be a key to determining the nature of the reaction path that gives the transformation its apparently perfect reversibility.

Download Full-text

Use of light microscopy in the qualitative and quantitative study of liquid crystalline order

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121727 ◽

1992 ◽

Vol 50 (1) ◽

pp. 264-265

Author(s):

Christopher Viney

Keyword(s):

Light Microscopy ◽

Liquid Crystalline ◽

Structural Characteristics ◽

Molecular Order ◽

Liquid Crystalline Phases ◽

Convenient Technique ◽

Liquid Crystalline Materials ◽

Transparent Windows

Light microscopy is a convenient technique for characterizing molecular order in fluid liquid crystalline materials. Microstructures can usually be observed under the actual conditions that promote the formation of liquid crystalline phases, whether or not a solvent is required, and at temperatures that can range from the boiling point of nitrogen to 600°C. It is relatively easy to produce specimens that are sufficiently thin and flat, simply by confining a droplet between glass cover slides. Specimens do not need to be conducting, and they do not have to be maintained in a vacuum. Drybox or other controlled environmental conditions can be maintained in a sealed chamber equipped with transparent windows; some heating/ freezing stages can be used for this purpose. It is relatively easy to construct a modified stage so that the generation and relaxation of global molecular order can be observed while specimens are being sheared, simulating flow conditions that exist during processing. Also, light only rarely affects the chemical composition or molecular weight distribution of the sample. Because little or no processing is required after collecting the sample, one can be confident that biologically derived materials will reveal many of their in vivo structural characteristics, even though microscopy is performed in vitro.

Download Full-text