Perceptual demand and distraction interactions mediated by task-control networks.

Modulation of selective attention appears to be under the guidance of a cluster of distinct task-control networks, the frontroparietal (FPN) and cingulo-opercular (CON). Yet, their role in mediating the relationship between task perceptual load and presence/absence of distraction in the auditory modality is unclear. Here, we examined this interaction using functional magnetic resonance imaging (fMRI) and an auditory signal detection task.

Hierarchical organization of speech perception in human auditory cortex.

Human speech consists of a variety of articulated sounds that vary dynamically in spectral composition. We investigated the neural activity associated with the perception of two types of speech segments: (a) the period of rapid spectral transition occurring at the beginning of a stop-consonant vowel (CV) syllable and (b) the subsequent spectral steady-state period occurring during the vowel segment of the syllable. Functional magnetic resonance imaging (fMRI) was recorded while subjects listened to series of synthesized CV syllables and non-phonemic control sounds.

The functional organization of the left STS: a large scale meta-analysis of PET and fMRI studies of healthy adults.

The superior temporal sulcus (STS) in the left hemisphere is functionally diverse, with sub-areas implicated in both linguistic and non-linguistic functions. However, the number and boundaries of distinct functional regions remain to be determined. Here, we present new evidence, from meta-analysis of a large number of positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies, of different functional specificity in the left STS supporting a division of its middle to terminal extent into at least three functional areas.

Neural effects of cognitive control load on auditory selective attention.

Whether and how working memory disrupts or alters auditory selective attention is unclear. We compared simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) responses associated with task-irrelevant sounds across high and low working memory load in a dichotic-listening paradigm. Participants performed n-back tasks (1-back, 2-back) in one ear (Attend ear) while ignoring task-irrelevant speech sounds in the other ear (Ignore ear).

Neural dynamics of phonological processing in the dorsal auditory stream.

Neuroanatomical models hypothesize a role for the dorsal auditory pathway in phonological processing as a feedforward efferent system (Davis and Johnsrude, 2007; Rauschecker and Scott, 2009; Hickok et al., 2011). But the functional organization of the pathway, in terms of time course of interactions between auditory, somatosensory, and motor regions, and the hemispheric lateralization pattern is largely unknown.

Perceptual demand modulates activation of human auditory cortex in response to task-irrelevant sounds.

In the visual modality, perceptual demand on a goal-directed task has been shown to modulate the extent to which irrelevant information can be disregarded at a sensory-perceptual stage of processing. In the auditory modality, the effect of perceptual demand on neural representations of task-irrelevant sounds is unclear. We compared simultaneous ERPs and fMRI responses associated with task-irrelevant sounds across parametrically modulated perceptual task demands in a dichotic-listening paradigm.

Neural events leading to and associated with detection of sounds under high processing load.

The neural events that lead to successful or failed detection of suprathreshold sounds are not well established. In this experiment, event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) were recorded while participants performed two tasks: a primary difficult duration judgment task on a sequence of tones presented to one ear, and a secondary target detection task on an auditory oddball stream presented to the other ear. The paradigm was designed to elicit competition and variability in detection of auditory targets despite identical input.

Attentional and linguistic interactions in speech perception.

The role of attention in speech comprehension is not well understood. We used fMRI to study the neural correlates of auditory word, pseudoword, and nonspeech (spectrally rotated speech) perception during a bimodal (auditory, visual) selective attention task. In three conditions, Attend Auditory (ignore visual), Ignore Auditory (attend visual), and Visual (no auditory stimulation), 28 subjects performed a one-back matching task in the assigned attended modality.

Involvement of the left anterior insula and frontopolar gyrus in odor discrimination.

Discriminating between successively presented odors requires brief storage of the first odor's perceptual trace, which then needs to be subsequently compared to the second odor in the pair. This study explores the cortical areas involved in odor discrimination and compares them with findings from studies of working-memory, traditionally investigated with n-back paradigms. Sixteen right-handed subjects underwent H(2) (15)O positron emission tomography during counterbalanced conditions of odorless sniffing, repeated single odor detection, multiple odor detection, and conscious successive discrimination between odor pairs.

Is the failure to detect stimulus deviance during sleep due to a rapid fading of sensory memory or a degradation of stimulus encoding?

The mismatch negativity (MMN) is thought to reflect the outcome of a system responsible for the detection of change in an otherwise repetitive, homogenous acoustic environment. This process depends on the storage and maintenance of a sensory representation of the frequently presented stimulus to which the deviant stimulus is compared. Few studies have been able to record the MMN in non-rapid eye movement (NREM) sleep.

Neural correlates of olfactory change detection.

Detecting changes in a stream of sensory information is vital to animals and humans. While there have been several studies of automatic change detection in various sensory modalities, olfactory change detection is largely unstudied. We investigated brain regions responsive to both passive and active detection of olfactory change using fMRI.

Olfactory system activation from sniffing: effects in piriform and orbitofrontal cortex.

Neuroimaging studies suggest that piriform cortex is activated at least in part by sniffing. We used H(2)(15)O positron emission tomography (PET) to study 15 healthy volunteers while they participated in four conditions, two of which were sniffing odorants and odorless air. The remaining two conditions involved a constant, very low flow of either odorized or odorless air during velopharyngeal closure (VPC), a technique that prevents subject-induced airflow through the nasal passages.

Alcohol-related olfactory cues activate the nucleus accumbens and ventral tegmental area in high-risk drinkers: preliminary findings.

Background: The mesocorticolimbic dopamine system is implicated in motivation and reward and may be involved in the development of alcoholism.

Methods: We used functional magnetic resonance imaging to study the blood oxygen level-dependent (BOLD) response to alcohol-related olfactory stimuli (AROS; odors of beer and whiskey) and non-alcohol-related olfactory stimuli (NAROS; odors of grass and leather) in 10 high-risk (HR) drinkers (average drinks per week, 19.99; SD, 6.

Neural correlates of auditory sensory memory and automatic change detection.

An auditory event-related potential component, the mismatch negativity (MMN), reflects automatic change detection and its prerequisite, sensory memory. This study examined the neural correlates of automatic change detection using BOLD fMRI and two rates of presentation previously shown to induce either a large or no MMN. A boxcar block design was employed in two functional scans, each performed twice.

Effects of sleep onset on the mismatch negativity (MMN) to frequency deviants using a rapid rate of presentation.

This study examined the effects of sleep onset-the transition from a waking, conscious state to one of sleep and unconsciousness-on the mismatch negativity (MMN) following frequency deviants when a rapid rate of stimulus presentation is employed. The MMN is thought to reflect a brief-lasting sensory memory. Rapid rates of stimulus presentation should guard the sensory memory from fading.

The effects of digital filtering on mismatch negativity in wakefulness and slow-wave sleep.

The mismatch negativity (MMN) is a response to a deviant auditory stimulus that occurs infrequently in a sequence of otherwise repetitive, homogeneous standard auditory stimuli. The MMN is presumed automatic and independent of conscious awareness. Recording of the MMN during unconscious states may be problematic.