Related Experiment Video
Updated: May 28, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
What can topology changes in the oddball N2 reveal about underlying processes?
Christopher M Warren1, James W Tanaka, Clay B Holroyd
1Department of Psychology, University of Victoria, Victoria, British Columbia, Canada. cwarren@uvic.ca
Neuroreport
|October 5, 2011
Summary
The oddball N2 event-related potential component
Area of Science:
- Cognitive Neuroscience
- Electrophysiology
Background:
- The anterior cingulate cortex is theorized to generate the oddball N2 component.
- Posterior scalp distributions of oddball N2s challenge this theory.
Purpose of the Study:
- To investigate the variable scalp distribution of the oddball N2.
- To propose that N2 reflects cortex-wide noradrenergic modulation influenced by task demands.
Main Methods:
- Participants performed an oddball task involving faces with varying colors and categories.
- Tasks required attending to either color or sex of the faces.
- Difference waves isolated the oddball N2 by subtracting frequent from infrequent trials.
Main Results:
- Oddball N2 showed a frontal-central maximal distribution when attending to color.
- Oddball N2 exhibited a lateral-occipital maximal distribution when attending to sex.
Conclusions:
- The oddball N2's scalp distribution varies based on task-specific cortical engagement.
- This variability supports the hypothesis of cortex-wide noradrenergic modulation influencing neural activity.
Related Concept Videos
01:06Nuclear Overhauser Enhancement (NOE)
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
01:21Entropy Changes Accompanying Specific Processes
Entropy, a measure of disorder in a system, changes during phase transitions like freezing or boiling. At the transition temperature Ttrs, where two phases are in equilibrium, the phase transition is a reversible process. The entropy change can be calculated from a substance's enthalpy of transition using the equation ΔStrs = ΔtrsH /Ttrs.When a perfect gas expands isothermally from one volume to another, entropy increases logarithmically with volume. Conversely, isothermal compression results...
02:02DNA Topoisomerases
Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:03Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...