Skip to main content

LPC subcomponents in a long-ISI dishabituation task

Journal Article


Abstract


  • The Late Positive Complex (LPC) of the event-related potential

    (ERP) has long been considered a central nervous system index of the

    orienting reflex (OR). Previous studies have found that when

    examined as a single ERP component, the LPC demonstrates habituation,

    and reflects stimulus characteristics that are associated with the

    OR (novelty, intensity, significance). However, a growing body of

    evidence suggests that the LPC is not simply a unitary complex. It has

    been shown that the LPC is composed of several distinct subcomponents,

    each with different topographic distributions and sensitivities to

    a variety of stimulus characteristics. Our previous work has aimed at

    systematically disentangling these subcomponents of the LPC in the

    OR context by employing a dishabituation paradigm with an 8 s

    stimulus onset asynchrony (SOA). In the present study, we aimed to

    extend our previous findings by exploring LPC subcomponents in a

    long-interstimulus interval (ISI) dishabituation task. Twenty four

    university students completed an auditory dishabituation task whilst

    their electrodermal and electroencephalographic activity was recorded.

    The task consisted of two counterbalanced blocks: indifferent,

    in which there were no task requirements; and significant, in which

    participants were instructed to count the stimuli. Stimuli consisted of

    1000 and 1500 Hz counterbalanced (standard, deviant) 60 dB tones

    that were separated by a random SOA of 12–15 s and delivered in the

    following sequence: 10 standards, 1 deviant, 2–4 standards. Skin

    conductance responses (SCRs) were extracted for each subject and

    each trial. Single-trial EOG-corrected ERPs from 32-sites were

    submitted to principal components analysis, from which five identifiable

    LPC subcomponentswere extracted:Novelty P3, P3a, P3b, and two

    SlowWaves (SW1 and SW2). As expected, SCR behaved as an OR index,

    demonstrating habituation (decrement, recovery, dishabituation) and

    larger magnitude responses to significant compared to indifferent

    stimuli. Novelty P3 evidenced topography-specific decrement over

    trials, a main effect of recovery, but little evidence of dishabituation.

    P3a and P3b also showed topographic decrement, but topographyspecific

    recovery and dishabituation were only apparent for P3a.

    Neither of the two SWs demonstrated habituation, but SW2 did

    evidence a main effect of condition. The LPC subcomponents identified

    here did not demonstrate a uniform response-pattern across trials and

    conditions. These findings suggest that the LPC represents a variety of

    distinct neural processes, and support the notion that the LPC should

    be examined further as a series of subcomponents, rather than a global

    complex. Importantly, our LPC findings differed from that of our

    previous work with shorter ISIs, with weaker trials effects for longer

    ISIs. Taken together, these findings suggest that the mechanisms

    underlying habituation of ERPs may be less functional when repetitive

    stimuli are separated by longer ISIs.

Publication Date


  • 2012

Citation


  • Steiner, G. Z., Barry, R. J. & De Blasio, F. M. (2012). LPC subcomponents in a long-ISI dishabituation task. International Journal of Psychophysiology, 85 (3), 314-314.

Ro Metadata Url


  • http://ro.uow.edu.au/hbspapers/3105

Number Of Pages


  • 0

Start Page


  • 314

End Page


  • 314

Volume


  • 85

Issue


  • 3

Abstract


  • The Late Positive Complex (LPC) of the event-related potential

    (ERP) has long been considered a central nervous system index of the

    orienting reflex (OR). Previous studies have found that when

    examined as a single ERP component, the LPC demonstrates habituation,

    and reflects stimulus characteristics that are associated with the

    OR (novelty, intensity, significance). However, a growing body of

    evidence suggests that the LPC is not simply a unitary complex. It has

    been shown that the LPC is composed of several distinct subcomponents,

    each with different topographic distributions and sensitivities to

    a variety of stimulus characteristics. Our previous work has aimed at

    systematically disentangling these subcomponents of the LPC in the

    OR context by employing a dishabituation paradigm with an 8 s

    stimulus onset asynchrony (SOA). In the present study, we aimed to

    extend our previous findings by exploring LPC subcomponents in a

    long-interstimulus interval (ISI) dishabituation task. Twenty four

    university students completed an auditory dishabituation task whilst

    their electrodermal and electroencephalographic activity was recorded.

    The task consisted of two counterbalanced blocks: indifferent,

    in which there were no task requirements; and significant, in which

    participants were instructed to count the stimuli. Stimuli consisted of

    1000 and 1500 Hz counterbalanced (standard, deviant) 60 dB tones

    that were separated by a random SOA of 12–15 s and delivered in the

    following sequence: 10 standards, 1 deviant, 2–4 standards. Skin

    conductance responses (SCRs) were extracted for each subject and

    each trial. Single-trial EOG-corrected ERPs from 32-sites were

    submitted to principal components analysis, from which five identifiable

    LPC subcomponentswere extracted:Novelty P3, P3a, P3b, and two

    SlowWaves (SW1 and SW2). As expected, SCR behaved as an OR index,

    demonstrating habituation (decrement, recovery, dishabituation) and

    larger magnitude responses to significant compared to indifferent

    stimuli. Novelty P3 evidenced topography-specific decrement over

    trials, a main effect of recovery, but little evidence of dishabituation.

    P3a and P3b also showed topographic decrement, but topographyspecific

    recovery and dishabituation were only apparent for P3a.

    Neither of the two SWs demonstrated habituation, but SW2 did

    evidence a main effect of condition. The LPC subcomponents identified

    here did not demonstrate a uniform response-pattern across trials and

    conditions. These findings suggest that the LPC represents a variety of

    distinct neural processes, and support the notion that the LPC should

    be examined further as a series of subcomponents, rather than a global

    complex. Importantly, our LPC findings differed from that of our

    previous work with shorter ISIs, with weaker trials effects for longer

    ISIs. Taken together, these findings suggest that the mechanisms

    underlying habituation of ERPs may be less functional when repetitive

    stimuli are separated by longer ISIs.

Publication Date


  • 2012

Citation


  • Steiner, G. Z., Barry, R. J. & De Blasio, F. M. (2012). LPC subcomponents in a long-ISI dishabituation task. International Journal of Psychophysiology, 85 (3), 314-314.

Ro Metadata Url


  • http://ro.uow.edu.au/hbspapers/3105

Number Of Pages


  • 0

Start Page


  • 314

End Page


  • 314

Volume


  • 85

Issue


  • 3