Studies of the Intact Human Brain: Implications for Performance, (9999)
Methodology provides a unifying theme for this conference. Many of the papers deal with electrical potentials and magnetic fields recorded at the scalp as well as with advances in the methods for...
The Evoked Magnetic Field of the Human Brain. (2002)
Kaufman,Lloyd, Williamson,Samuel J.
Instrumentation and procedures for detecting neuromagnetic fields evoked by sensory stimuli in an unshielded environment are described. Latencies of somatosensory and visually evoked neuromagnetic...
Magnetic Fields of the Cerebral Cortex, (2002)
Williamson,Samuel J., Kaufman,Lloyd
The observed patterns over the scalp of magnetic fields evoked by visual, somatic, and auditory stimuli are analyzed to deduce the position and depth of the equivalent current dipole generating...
Evoked Magnetic Fields Reveal Different Visual Areas in Human Cortex, (2002)
Brenner,Douglas, Okada,Yoshio, Maclin,Edward, Williamson,Samuel J., Kaufman,Lloyd
Detailed maps of the patterns of steady state magnetic fields evoked by visual stimuli were constructed from measurements made over the occipital region of the head. The maps indicate the presence of...
Okada,Yoshio C., Kaufman,Lloyd, Brenner,Douglas, Williamson,Samuel J.
Magnetic field measurements have detected and localized transient neural activity evoked in the primary somatosensory projection area of the cortex following stimulation of the medial nerve....
Perceptual Factors in Workload: A Neuromagnetic Study. (2002)
Kaufman,Lloyd, Williamson,Samuel J.
A background section describes the neuromagnetic method and its history. There were an elevation of N1 and P2 (using a quasi-steady state stimulus). The fields associated with these sources increased...
Kaufman,Lloyd, Donchin,Emanuel
A study was conducted to evaluate the feasibility of obtaining concurrent measures of event-related potentials (ERPs), and event-related magnetic fields (ERFs). Subjects participated in an oddball...
The Perception of the Higher Derivatives of Visual Motion. (2002)
Kaufman,Lloyd, Williamson,Samuel J.
Sensitivity to changing speed was studied with gratings of various spatial frequencies drifting across a screen while the average velocity was modulated. Thresholds expressed either as the velocity...
The Perception of the Higher Derivatives of Visual Motion. (2002)
Kaufman,Lloyd, Williamson,Samuel J.
This report describes theoretical work involved in the early stages of this research effort and gives a brief review of the literature studied during that work. In particular, it reviews work on...
Neuromagnetic Investigation of Workload and Attention. (2002)
Kaufman,Lloyd, Williamson,Samuel J.
During the period covered by this report, we made major advances in the technology associated with neuromagnetic measurements. These included the demonstration of the effectiveness of electronic...
Perceptual Factors in Workload: A Neuromagnetic Study. (2002)
Kaufman,Lloyd, Williamson,Samuel J.
This annual report describes the five channel neuromagnetometer operating at NYU, and the principles underlying its use. If further describes recent advances in methodology, including the results of...
Perception of Higher Derivatives of Visual Motion. (1998)
Kaufman,Lloyd, Williamson,Samuel J.
This document describes a basic experiment involving the sensitivity of the visual system to the modulation of speed of gratings moving in one direction across the visual field. The gratings were of...
Williamson,Samuel J., Romani,Gian-Luca, Kaufman,Lloyd, Modena,Ivo
Contents: Magnetic quantities, Units, Materials, and Measurements; Cryogenics; Squid sensors; Detection Coils; Physical Concepts and Mathematical Models; Electrophysiology of Excitable Cells and...
Method for Locating a Small Magnetic Object in the Human Body, (1998)
Kaufman, Lloyd, Williamson, Samuel J., Ilmoniemi, Risto J., Weinberg, Harold, Boyd, Arthur D.
A piece of a thin acupuncture needle lodged under the right scapula of a patient could not be found in surgical procedures accompanied by studies of 30 standard X-ray images. To locate it, we mapped...
Cognitive and Neural Bases of Skilled Performance. (1998)
Research in seven interrelated areas has been carried out during this first year. A major advance in the capability of neuromagnetic monitoring of higher levels of brain function was achieved with...
Methods and Instrumentation for Biomagnetism. (1998)
Kaufman, Lloyd, Williamson, Samuel J., Robinson, S. E.
Capabilities for biomagnetic measurements have been advanced by the successful development of a Superconducting Quantum Interference Device(SQUID)-based magnetic sensor that does not rely on liquid...
Divided Attention Revisited: Selection Based on Location or Pitch. (1998)
Kaufman, Lloyd, Williamson, Samuel J., Curtis, S.
The affect of attention on the level of cortical activity in human subjects was investigated by use of a novel paradigm involving the rapid and simultaneous presentation of two sequences of tones...
Kaufman, Lloyd, Williamson, Samuel J., Costa Ribeiro, P.
Recently developed small arrays of SQUID-based magnetic sensors can, if appropriately placed, locate the position of a confined biomagnetic source without moving the array. The authors present a...
CyroSQUID: A SQUID-Based Magnetic Field Sensor. (1998)
Williamson, S. J., Kaufman, Lloyd
A new type of neuromagnetometer has been developed to enhance the capability for measuring the magnetic field of the human brain. This system - known as CryoSQUID - results from the marriage of two...
Perceptual Factors in Workload: A Neuromagnetic Study. (1998)
Kaufman, Lloyd, Williamson, Samuel J.
This final report includes descriptions of substantive experimental studies of neural phenomena related to attention and auditory perception. It also describes efforts to enhance the superconducting...
Attention, Imagery and Memory: A Neuromagnetic Investigation. (1998)
This report describes a number of experiments related to the effects of mental imagery and other high-level cognitive tasks on the spontaneous activity of the brain. The basic procedure involves...
Modulation of Spontaneous Brain Activity During Mental Imagery. (1998)
Magnetic measurements of average power of human alpha activity over the occipital and parietal areas of the scalp reveal spatially selective suppression when abstract figures are briefly presented...
Visualizing and Rhyming Cause Differences in Alpha Suppression. (1998)
Alpha rhythms of the EEG are strongest at the occipital regions of the head, and the visual cortex is apparently a major contributor. It has been suggested that visual cortex is involved in forming...
Cognitive and Neural Bases of Skilled Performance. (1998)
The results obtained using an odd-ball paradigm were inconclusive, but a new procedure was developed which uses all trials rather than trials on which only infrequent events lead to P300 responses....
Attention, Imagery, and Memory: A Neuromagnetic Investigation. (1998)
Kaufman, Lloyd, Williamson, Samuel J.
This report describes work on mental imagery, short term memory scanning, language-related mental tasks, and visual attention. In the field of mental imagery it was found that searching memory to...
Cognitive and Neural Bases of Skilled Performance. (1998)
Kaufman, Lloyd, Williamson, Samuel J.
Major improvements were introduced for neuromagnetic studies by the installation of a magnetically shielded room and versatile gantry to hold our 5-sensor neuromagnetometer. Studies with this system...
Cognition and the Brain. (1998)
Kaufman, Lloyd, Williamson, Samuel J.
Using an array of 14 superconducting magnetic field sensors we succeeded in establishing the locations of neuronal activity that produce the dominant alpha rhythm recorded in the electroencephalogram...
Attention, Imagery and Memory: A Neuromagnetic Investigation. (1998)
Kaufman, Lloyd, Williamson, Samuel J.
The techniques of magnetic source imaging (MSI) have been applied to studies of three important aspects of human cognition: (1) An investigation of the effects of selective spatial attention on...
Neuromagnetic Investigations of Cortical Regions Underlying Short-Term Memory. (1998)
Williamson, Samuel J., Kaufman, Lloyd
Spontaneous neuronal activity of the brain within the alpha frequency bandwidth is found to be suppressed in visual cortex when comparing a rotated, and possibly inverted object with an object...
Wang, Jia Z., Kaufman, Lloyd, Williamson, Samuel J.
A method has been developed to determine the distribution of average spontaneous neuronal activity across the cerebral cortex from measurements of the field pattern across the human scalp....
The main focus of this project was the make use of magneto encephalographic (MEG) measures of brain activity to determine how the brain's neural resources are deployed during various cognitive tasks...
Handbook of Perception and Human Performance. Volume 2. Cognitive Processes and Performance, (1998)
Boff, Kenneth R., Kaufman, Lloyd, Thomas, James P.
This chapter has attempted to bring together the laboratory and field-based techniques currently in use to assess workload. No doubt, many specific procedures of interest to particular applications...
Project (M.S.W.)--University of Iowa.
Kaufman, Lloyd, Kaufman, James H.
An old explanation of the moon illusion holds that various cues place the horizon moon at an effectively greater distance than the elevated moon. Although both moons have the same angular size, the...
Kaufman, Lloyd, Kaufman, James H.
An old explanation of the moon illusion holds that various cues place the horizon moon at an effectively greater distance than the elevated moon. Although both moons have the same angular size, the...