Faculty Opinions recommendation of Temporal encoding of spatial information during active visual fixation.

1. The present paper reports complex neural activities in the monkey caudate nucleus that precede and anticipate visual stimuli and reward in learned visuomotor paradigms. These activities were revealed typically in the delayed saccade task in which memory and anticipation were required. We classified these activities according to their relationships to the task. 2. Activity related to expectation of a cue (n = 46) preceded the presentation of a spot of light (target cue) that signified the future location of saccade target. When the target cue was delayed, the activity was prolonged accordingly. The same spot of light was preceded by no activity if it acted as a distracting stimulus. 3. The sustained activity (n = 80) was a tonic discharge starting after the target cue as if holding the spatial information. 4. The activity related to expectation of target (n = 109) preceded the appearance of the target whose location was cued previously. It started with or after a saccade to the cued target location and ended with the appearance of the target. The activity was greater when the target was expected to appear in the contralateral visual field. 5. The activity related to expectation of reward (n = 57) preceded a task-specific reward. It started with the appearance of the final target and ended with the reward. In most cases, the activity was nonselective for how the monkey obtained the reward, i.e., by visual fixation only, by a saccade, or by a hand movement. The activity was dependent partly on visual fixation. 6. A few neurons showed tonic activity selectively before lever release and are thus considered to be related to the preparation of hand movements. 7. The activity related to breaking fixation (n = 33) occurred phasically if the monkey broke fixation, aborting the trial. 8. Activity related to reward (n = 104) was a phasic discharge that occurred before or after a reward of water was delivered. The activity was not simply related to a specific movement involved in the reward-obtaining behavior (eye, hand, or mouth movement). 9. Fixation-related activity (n = 72) was tonic activity continuing as long as the monkey attentively fixated a spot of light. It was dependent on reward expectancy in most cases. 10. The present results, together with those in the preceding papers, indicate that the activities of individual caudate neurons--sensory, motor, or cognitive--are dependent on specific contexts of learned behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

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Spatio-temporal encoding by quadratic gradients in magnetic resonance imaging

10.5194/mr-2019-2 ◽

2019 ◽

Author(s):

Sina Marhabaie ◽

Geoffrey Bodenhausen ◽

Philippe Pelupessy

Keyword(s):

Spatial Information ◽

Signal To Noise Ratio ◽

Magnetic Field Gradient ◽

Quadratic Function ◽

Transverse Magnetization ◽

Chirp Pulse ◽

Simultaneous Application ◽

Quadratic Phase ◽

Temporal Encoding ◽

Spatio Temporal

Abstract. SPatio-temporal ENcoding (SPEN) MRI is a non-Fourier imaging technique that encodes the spatial information in such a way that there is a one-to-one correspondence between the signal intensity as a function of time and the spin density at the corresponding position. In current spatio-temporal encoding methods imparting a quadratic phase – that is the phase of the transverse magnetization depends as a quadratic function of the spatial coordinates – onto the transverse magnetization is the first crucial step. Usually, this is achieved by simultaneous application of a frequency-swept (chirp) pulse and a linear magnetic field gradient. In this work, we show that it can be advantageous to use quadratic encoding gradients for this purpose. By avoiding chirp pulses one can achieve much smaller specific absorption rates (SARs), and shorter echo times (TEs), while the spatial resolution, the field of view (FOV), and the signal-to-noise ratio (SNR) are the same as in SPEN if one uses similar parameters. In addition, the proposed sequence can readily be used for multi-slice applications.

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Practical Picture Processing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051700 ◽

1974 ◽

Vol 32 ◽

pp. 338-339

Author(s):

T. A. Welton

Keyword(s):

Radiation Damage ◽

Coherence Length ◽

Spatial Information ◽

State Of The Art ◽

Coherent Radiation ◽

The State ◽

Energy Spread ◽

Electron Micrograph ◽

Picture Processing ◽

Molecular Skeleton

Various authors have emphasized the spatial information resident in an electron micrograph taken with adequately coherent radiation. In view of the completion of at least one such instrument, this opportunity is taken to summarize the state of the art of processing such micrographs. We use the usual symbols for the aberration coefficients, and supplement these with £ and 6 for the transverse coherence length and the fractional energy spread respectively. He also assume a weak, biologically interesting sample, with principal interest lying in the molecular skeleton remaining after obvious hydrogen loss and other radiation damage has occurred.

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3-D optical transfer in excitation field synthesis microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136696 ◽

1995 ◽

Vol 53 ◽

pp. 64-65

Author(s):

Vijay Krishnamurthi ◽

Brent Bailey ◽

Frederick Lanni

Keyword(s):

Standing Wave ◽

Spatial Information ◽

3D Structure ◽

Complete Recovery ◽

Weighting Factor ◽

Optical Transfer Function ◽

Excitation Field ◽

Optical Transfer ◽

Set Up ◽

Focus Plane

Excitation field synthesis (EFS) refers to the use of an interference optical system in a direct-imaging microscope to improve 3D resolution by axially-selective excitation of fluorescence within a specimen. The excitation field can be thought of as a weighting factor for the point-spread function (PSF) of the microscope, so that the optical transfer function (OTF) gets expanded by convolution with the Fourier transform of the field intensity. The simplest EFS system is the standing-wave fluorescence microscope, in which an axially-periodic excitation field is set up through the specimen by interference of a pair of collimated, coherent, s-polarized beams that enter the specimen from opposite sides at matching angles. In this case, spatial information about the object is recovered in the central OTF passband, plus two symmetric, axially-shifted sidebands. Gaps between these bands represent "lost" information about the 3D structure of the object. Because the sideband shift is equal to the spatial frequency of the standing-wave (SW) field, more complete recovery of information is possible by superposition of fields having different periods. When all of the fields have an antinode at a common plane (set to be coincident with the in-focus plane), the "synthesized" field is peaked in a narrow infocus zone.

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Use of EDS mapping to characterize thermochemical stability of fibers in intermetallic matrix composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012120x ◽

1992 ◽

Vol 50 (1) ◽

pp. 160-161

Author(s):

John R. Porter

Keyword(s):

Spatial Information ◽

Beam Current ◽

Fiber Types ◽

Ceramic Fibers ◽

Dye Transfer ◽

Science Center ◽

Commercial Development ◽

Nih Image ◽

Intermetallic Matrix Composites ◽

Thermochemical Stability

New ceramic fibers, currently in various stages of commercial development, have been consolidated in intermetallic matrices such as γ-TiAl and FeAl. Fiber types include SiC, TiB2 and polycrystalline and single crystal Al2O3. This work required the development of techniques to characterize the thermochemical stability of these fibers in different matrices.SEM/EDS elemental mapping was used for this work. To obtain qualitative compositional/spatial information, the best realistically achievable counting statistics were required. We established that 128 × 128 maps, acquired with a 20 KeV accelerating voltage, 3 sec. live time per pixel (total mapping time, 18 h) and with beam current adjusted to give 30% dead time, provided adequate image quality at a magnification of 800X. The maps were acquired, with backgrounds subtracted, using a Noran TN 5500 EDS system. The images and maps were transferred to a Macintosh and converted into TIFF files using either TIFF Maker, or TNtolMAGE, a Microsoft QuickBASIC program developed at the Science Center. From TIFF files, images and maps were opened in either NIH Image or Adobe Photoshop for processing and analysis and printed from Microsoft Powerpoint on a Kodak XL7700 dye transfer image printer.

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Characterisation of multilayer materials using a position-sensitive atom probe

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176253 ◽

1990 ◽

Vol 48 (4) ◽

pp. 624-625

Author(s):

RAD Mackenzie ◽

G D W Smith ◽

A. Cerezo ◽

J A Liddle ◽

CRM Grovenor ◽

...

Keyword(s):

Quantum Well ◽

Quantum Wells ◽

Spatial Information ◽

Chemical Vapour ◽

Atom Probe ◽

Organic Chemical ◽

Growth Stages ◽

Multiple Quantum ◽

Quartz Wool ◽

Position Sensitive

The position sensitive atom probe (POSAP), described briefly elsewhere in these proceedings, permits both chemical and spatial information in three dimensions to be recorded from a small volume of material. This technique is particularly applicable to situations where there are fine scale variations in composition present in the material under investigation. We report the application of the POSAP to the characterisation of semiconductor multiple quantum wells and metallic multilayers.The application of devices prepared from quantum well materials depends on the ability to accurately control both the quantum well composition and the quality of the interfaces between the well and barrier layers. A series of metal organic chemical vapour deposition (MOCVD) grown GaInAs-InP quantum wells were examined after being prepared under three different growth conditions. These samples were observed using the POSAP in order to study both the composition of the wells and the interface morphology. The first set of wells examined were prepared in a conventional reactor to which a quartz wool baffle had been added to promote gas intermixing. The effect of this was to hold a volume of gas within the chamber between growth stages, leading to a structure where the wells had a composition of GalnAsP lattice matched to the InP barriers, and where the interfaces were very indistinct. A POSAP image showing a well in this sample is shown in figure 1. The second set of wells were grown in the same reactor but with the quartz wool baffle removed. This set of wells were much better defined, as can be seen in figure 2, and the wells were much closer to the intended composition, but still with measurable levels of phosphorus. The final set of wells examined were prepared in a reactor where the design had the effect of minimizing the recirculating volume of gas. In this case there was again further improvement in the well quality. It also appears that the left hand side of the well in figure 2 is more abrupt than the right hand side, indicating that the switchover at this interface from barrier to well growth is more abrupt than the switchover at the other interface.

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Phonological and Spatial Processing Abilities in Language- and Reading-Impaired Children

Journal of Speech and Hearing Disorders ◽

10.1044/jshd.5303.316 ◽

1988 ◽

Vol 53 (3) ◽

pp. 316-327 ◽

Cited By ~ 109

Author(s):

Alan G. Kamhi ◽

Hugh W. Catts ◽

Daria Mauer ◽

Kenn Apel ◽

Betholyn F. Gentry

Keyword(s):

Phonological Processing ◽

Spatial Information ◽

Normal Children ◽

Language Impaired ◽

Word Repetition ◽

Paper Folding ◽

Syllable Segmentation ◽

Processing Abilities ◽

Impaired Children ◽

Better Than

In the present study, we further examined (see Kamhi & Catts, 1986) the phonological processing abilities of language-impaired (LI) and reading-impaired (RI) children. We also evaluated these children's ability to process spatial information. Subjects were 10 LI, 10 RI, and 10 normal children between the ages of 6:8 and 8:10 years. Each subject was administered eight tasks: four word repetition tasks (monosyllabic, monosyllabic presented in noise, three-item, and multisyllabic), rapid naming, syllable segmentation, paper folding, and form completion. The normal children performed significantly better than both the LI and RI children on all but two tasks: syllable segmentation and repeating words presented in noise. The LI and RI children performed comparably on every task with the exception of the multisyllabic word repetition task. These findings were consistent with those from our previous study (Kamhi & Catts, 1986). The similarities and differences between LI and RI children are discussed.

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Human Event-Related Potentials to Higher-Order Acoustic Spatial Changes

Journal of Psychophysiology ◽

10.1027//0269-8803.16.2.114 ◽

2002 ◽

Vol 16 (2) ◽

pp. 114-118 ◽

Cited By ~ 1

Author(s):

Timo Ruusuvirta ◽

Heikki Hämäläinen

Keyword(s):

Working Memory ◽

Mismatch Negativity ◽

Spatial Information ◽

Free Field ◽

Event Related Potentials ◽

Negative Polarity ◽

Positive Polarity ◽

Spatial Changes ◽

Related Potentials ◽

Human Event

Abstract Human event-related potentials (ERPs) to a tone continuously alternating between its two spatial loci of origin (middle-standards, left-standards), to repetitions of left-standards (oddball-deviants), and to the tones originally representing these repetitions presented alone (alone-deviants) were recorded in free-field conditions. During the recordings (Fz, Cz, Pz, M1, and M2 referenced to nose), the subjects watched a silent movie. Oddball-deviants elicited a spatially diffuse two-peaked deflection of positive polarity. It differed from a deflection elicited by left-standards and commenced earlier than a prominent deflection of negative polarity (N1) elicited by alone-deviants. The results are discussed in the context of the mismatch negativity (MMN) and previous findings of dissociation between spatial and non-spatial information in auditory working memory.

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The Effect of Path Length and Display Size on Memory for Spatial Information

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169/a000137 ◽

2012 ◽

Vol 59 (3) ◽

pp. 147-152 ◽

Cited By ~ 11

Author(s):

Katherine Guérard ◽

Sébastien Tremblay

Keyword(s):

Path Length ◽

Potential Role ◽

Spatial Information ◽

Recall Performance ◽

Minor Role ◽

Length Effect ◽

Serial Memory ◽

Fixed Reference ◽

A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

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