We would like to thank Jyoti Mishra for useful discussions regarding the paradigm. This research was supported by NIH grants R33DA026109 and R21MH096329 to MSC.

NOTE: This study protocol was developed in accordance with the ethical guidelines approved by the investigational review board at University of California Los Angles.
1. Preparation of Auditory and Visual Stimuli
<ol>
	<li>Using software in which visual images can be generated, create two gray scale sinusoid gratings, approximately 5.7 inches in diameter and of any frequency (e.g., 1.36 cycles/degree of visual angle). The images will have an on-screen duration of 100 msec.
	<ol>
		<...

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Processes related to attending and to ignoring in attention control may involve different neural pathways and time courses. Therefore, it is of value to measure these processes separately. The IMAT is a tool, by which one may capture neurophysiological signals of attending and ignoring separately, but concurrently, in sustained attention. The critical steps include the measurement of sensory neurophysiological responses when the participant is attending, ignoring or passively perceiving stimuli presented in a given modal...

Attention control guides behavior by directing our neural and cognitive resources toward select input signals, while restricting access to other signals, based on a given behavioral goal 1. For instance, when reading a book, the visual signals corresponding to the book are the target signals to be enhanced, whereas other sensory signals &#8212; such as the TV in the next room &#8212; are distractor signals to be attenuated. Recordings in both human and non-human primates 1-4, indicate that neural responses in sensory cortices are enhanced for attended targets relative to ignored distractors during selective attention, indicating that the strength of sensory inputs in the brain is modulated as a function of whether they are classified as targets or distractors 5-7. We refer to this difference in signal strength when attending versus ignoring as the attention modulation effect.
Of increasing interest is the question of whether and how the neural processes of attending contribute to attention control and its impairments, separately from the neural processes of ignoring. It is increasingly clear that the ability to ignore distractions can be impaired independently from our ability to attend targets. For instance, distractor-suppression can be impaired with increased task load 8, cognitive aging 9 and sleep deprivation 10, without a decrement in target enhancement. It is not currently known if a decrement in target enhancement can also exist without a deficit in distractor suppression. Perhaps more importantly, it is not resolved whether deficits of either attending or ignoring, but not both, can elucidate neuropsychiatric conditions in which attention control is impaired. As such, it is valuable to better understand whether attending and ignoring arise from separable cortical pathways, if and how they differ in neural dynamics. By measuring attending and ignoring processes separately, such questions can be addressed.
Here we describe methodology to measure the neurophysiological signals of attending and ignoring separately, but concurrently, in sustained attention. This approach builds on the attention modulation effect: the difference in amplitude of a neural sensory response when the individual is attending versus ignoring to stimuli in that sensory stream. The attention modulation effect is a powerful tool for detecting attention modulation over sensory signals, but it precludes the ability to assess the separate dynamics of attending and ignoring processes. Namely, a difference in neural sensory responses when attending versus ignoring could arise because the process of attention enhances sensory target signals, or because ignoring attenuates sensory distractor signals, or both. To test between these alternatives, the use of an additional control condition is required in which one quantifies the strength of sensory inputs at their natural baseline, when they are neither attended nor ignored. This is similar to walking down a busy street full of cars, but neither actively watching (e.g., for a taxi) nor actively ignoring (e.g., non-taxi cars and buses) the passing cars. By evaluating sensory signals that are attended or ignored, relative to a passive reference condition, the magnitude and timing of attending and ignoring processes can be quantified separately.
Effective uses of such a passive control in measuring attending and ignoring processes have been reported previously in studies of anticipatory attention 11-13 and memory-attention interactions 9,10,14-17. Here we describe the use of this approach in the context of sustained attention, in a non-cued, continuous, intermodal (i.e., auditory-visual) attention task (IMAT) 18. In other words, this method is appropriate to the study of ongoing rather than preparatory control processes, allowing for tracking of these processes across time. This method also quantifies control processes that modulate sensory responses across different sensory modalities (i.e., auditory versus visual), thus focusing on processes that are not specialized to within a particular sensory or content domain. Unlike previous functional magnetic resonance imaging studies 15,19,20, this method tracks attending and ignoring processes using temporally resolved neurophysiological signals (electroencephalography, EEG), thus providing millisecond resolution on the temporal profiles of attending and ignoring processes. Our representative results demonstrate the use of the technique in identifying direct evidence for separable cortical sources and temporal dynamics of the neural processes of attending and ignoring, and unique contributions to the attention modulation effect.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>NetStation Software</td>
			<td>Electrical Geodesic, Inc.</td>
			<td>version 4.5.1</td>
			<td>Alternate recording software may be used.</td>
		</tr>
		<tr>
			<td>Matlab Software</td>
			<td>The MathWorks, Inc.</td>
			<td>7.10.0 (R2010a)</td>
			<td>Alternate analysis and presentation software may be used.</td>
		</tr>
		<tr>
			<td>PsychToolbox Software</td>
			<td>http://psychtoolbox.org/</td>
			<td>v3.0.8 (2010-03-06)</td>
			<td>Open-source software. Alternate stimulus presentation software may be used.</td>
		</tr>
		<tr>
			<td>Netstation Amplifier</td>
			<td>Electrical Geodesic, Inc.</td>
			<td>300</td>
			<td>Alternate amplifier may be used.</td>
		</tr>
		<tr>
			<td>EEG Net</td>
			<td>Electrical Geodesic, Inc.</td>
			<td>HCGSN130</td>
			<td>Alternate EEG cap may be used.</td>
		</tr>
		<tr>
			<td>Saline-Based Electrolyte (Potassium Chloride)</td>
			<td>Electrical Geodesic, Inc.</td>
			<td>n/a</td>
			<td>Electrolyte used in soaking of net for this high-impedance EEG system. Alternate electrolyte mediate can be used.</td>
		</tr>
	</tbody>
</table>

measurement of neurophysiological signals of ignoring and attending processes in attention control

Attention control is the ability to selectively attend to some sensory signals while ignoring others. This ability is thought to involve two processes: enhancement of sensory signals that are to be attended and the attenuation of sensory signals that are to be ignored. The overall strength of attentional modulation is often measured by comparing the amplitude of a sensory neural response to an external input when attended versus when ignored. This method is robust for detecting attentional modulation, but precludes the ability to assess the separate dynamics of attending and ignoring processes. Here, we describe methodology to measure independently the neurophysiological signals of attending and ignoring using the intermodal attention task (IMAT). This task, when combined with electroencephalography, isolates neurophysiological sensory responses in auditory and visual modalities, when either attending or ignoring, with respect to a passive control. As a result, independent dynamics of attending and of a ignoring can be assessed in either modality. Our results using this task indicate that the timing and cortical sources of attending and ignoring effects differ, as do their contributions to the attention modulation effect, pointing to unique neural trajectories and demonstrating sample utility of measuring them separately.

The IMAT protocol has been used previously to identify the unique contributions of attending and ignoring processes to response speed during sustained attention 18. In that study, we tested 35 healthy right-handed individuals (22 female, age: x&#773; = 21.0, &#963; = 5.4), recruited through the Psychology department subject pool at the University of California, Los Angeles. All participants provided written informed consent prior to participating in the study. Representative results highlight the value of meas...

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Measurement of Neurophysiological Signals of Ignoring and Attending Processes in Attention Control

Attention control comprises enhancement of target signals and attenuation of distractor signals. We describe an approach to measure separately but concurrently, the neurophysiology of attending and ignoring in sustained intermodal attention, utilizing a passive control condition during which neither process is continuously engaged.

Attention control is the ability to selectively attend to some sensory signals while ignoring others. This ability is thought to involve two processes: ...

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9.0K vistas.  University of California Los Angeles. Attention control comprises enhancement of target signals and attenuation of distractor signals. We describe an approach to measure separately but concurrently, the neurophysiology of attending and ignoring in sustained intermodal attention, utilizing a passive control condition during which neither process is continuously engaged. 