Biomedical subjects

Michael A Kisley

Publications and source records attributed to Michael A Kisley.

12 recordsLinked to original sources

PubMed2006

Gamma and beta neural activity evoked during a sensory gating paradigm: effects of auditory, somatosensory and cross-modal stimulation.

OBJECTIVE: Stimulus-driven salience is determined involuntarily, and by the physical properties of a stimulus. It has recently been theorized that neural coding of this variable involves oscillatory activity within cortical neuron populations at beta frequencies. This was tested here through experimental manipulation of inter-stimulus interval (ISI). METHODS: Non-invasive neurophysiological measures of event-related gamma (30-50 Hz) and beta (12-20 Hz) activity were estimated from scalp-recorded evoked potentials. Stimuli were presented in a standard "paired-stimulus" sensory gating paradigm, where the S1 (conditioning) stimulus was conceptualized as long-ISI, or "high salience", and the S2 (test) stimulus as short-ISI, or "low salience". Three separate studies were conducted: auditory stimuli only (N = 20 participants), somatosensory stimuli only (N = 20), and a cross-modal study for which auditory and somatosensory stimuli were mixed (N = 40). RESULTS: Early (20-150 ms) stimulus-evoked beta activity was more sensitive to ISI than temporally-overlapping gamma-band activity, and this effect was seen in both auditory and somatosensory studies. In the cross-modal study, beta activity was significantly modulated by the similarity (or dissimilarity) of stimuli separated by a short ISI (0.5 s); a significant cross-modal gating effect was nevertheless detected. CONCLUSIONS: With regard to the early sensory-evoked response recorded from the scalp, the interval between identical stimuli especially modulates beta oscillatory activity. SIGNIFICANCE: This is consistent with developing theories regarding the different roles of temporally-overlapping oscillatory activity within cortical neuron populations at gamma and beta frequencies, particularly the claim that the latter is related to stimulus-driven salience.

Acoustic Stimulation↗

PubMed2006

The negativity bias is eliminated in older adults: age-related reduction in event-related brain potentials associated with evaluative categorization.

Studies of younger adults have found that negative information has a stronger influence than positive information across a wide range of domains. T. A. Ito, J. T. Larsen, N. K. Smith, and J. T. Cacioppo (1998) reported that during evaluative categorization, extreme negative images produced greater brain activity than did equally extreme positive images in younger adults. Older adults have been reported to optimize affect and attend less to negative information. In this article, the negativity bias was examined in 20 older versus 20 younger adults during evaluative categorization, with a focus on brain activity occurring roughly 500 ms after presentation of visual stimuli. Results demonstrated a significant decrease in brain activity to both positive and negative stimuli (p < .05) and an elimination of the negativity bias in older adults.

Adolescent↗

PubMed2005

Age-related change in neural processing of time-dependent stimulus features.

Aging is associated with changes in automatic processing of task-irrelevant stimuli, and this may lead to functional disturbances including repeated orienting to nonnovel events and distraction from task. The effect of age on automatic processing of time-dependent stimulus features was investigated by measurement of the auditory mismatch negativity (MMN) in younger (18-23) and older (55-85) adults. Amplitude of MMN recorded during a paradigm involving low-probability deviation in interstimulus interval (from 500 ms to 250 ms) was found to be reduced in the older group at fronto-central sites. This effect was paralleled by, and correlated to, decreased sensory gating efficiency for component N1 recorded during a separate paradigm involving alternate presentation of auditory stimuli at long (9 s) and short (0.5 s) interstimulus intervals. Further, MMN amplitude was correlated to behavioral performance on a small subset of neuropsychological tests, including the Rey Auditory Verbal Learning Test, within a group of healthy older adults. The results support the hypothesis that aging is associated with declines in automatic processing of time-dependent stimulus features, and this is related to cognitive function. These conclusions are considered in the context of age-related declines in prefrontal cortex function and associated increases in susceptibility to task-irrelevant stimuli.

Acoustic Stimulation↗

PubMed2005

Behavioral and electrophysiological indices of temporal processing dysfunction in schizophrenia.

Timing deficits in schizophrenia have been noted in several behavioral studies. However, the involvement of mediating factors, such as inattention, has not been ruled out as contributing to these effects. Mismatch negativity (MMN), an electrophysiological measure, may provide a more direct index of stimulus processing ability in individuals with schizophrenia. The current study explored the relationship between behavioral time judgments and a time-based MMN paradigm. Participants were administered two MMN paradigms consisting of an "easy" or "difficult" deviant and an analogous behavioral measure of time processing. Matched against a healthy comparison group, patients exhibited decreased MMN amplitude on the "difficult" deviant interval only. However, on the behavioral paradigm, the patients made significantly more errors across all conditions. These results suggest that behavioral measures of time processing may reflect different processes than those captured by preattentive physiological measures in this population.

Acoustic Stimulation↗

PubMed2005

Early biomarkers of psychosis.

Biological traits that are predictive of the later development of psychosis have not yet been identified. The complex, multidetermined nature of schizophrenia and other psychoses makes it unlikely that any single biomarker will be both sensitive and specific enough to unambiguously identify individuals who will later become psychotic. However, current genetic research has begun to identify genes associated with schizophrenia, some of which have phenotypes that appear early in life. While these phenotypes have low predictive power for identifying individuals who will become psychotic, they do serve as biomarkers for pathophysiological processes that can become the targets of prevention strategies. Examples are given from work on the role of the alpha(T)nicotinic receptor and its gene CHRNA7 on chromosome 15 in the neurobiology and genetic transmission of schizophrenia.

Biomarkers↗

PubMed2004

Small changes in temporal deviance modulate mismatch negativity amplitude in humans.

The relative sensitivity of mismatch negativity (MMN) amplitude to small changes in temporal (i.e. timing) deviance of an ongoing stimulus train was investigated. MMN was measured at Fz in response to 3.75-15% decrements of inter-stimulus interval from a 400 ms standard with a deviant probability of 1/15. This parameter space represents the smallest degree of deviance and the narrowest range of variation that has been tested in the context of MMN sensitivity to temporal variables. Waveform amplitude was found to significantly increase with degree of temporal deviance even within this relatively narrow parameter space. This finding is consistent with the view that the MMN corresponds to pre-attentive neural activity that subsequently allows the conscious perception of time during temporal discrimination tasks.

Acoustic Stimulation↗

PubMed2004

Comparison of sensory gating to mismatch negativity and self-reported perceptual phenomena in healthy adults.

To better understand the possible functional significance of electrophysiological sensory gating measures, response suppression of midlatency auditory event related potential (ERP) components was compared to the mismatch negativity (MMN) and to self-rated indices of stimulus filtering and passive attention-switching phenomena in an age-restricted sample of healthy adults. P1 sensory gating, measured during a paired-click paradigm, was correlated with MMN amplitude, measured during an acoustic oddball paradigm (intensity deviation). Also, individuals that exhibited less robust P1 suppression endorsed higher rates of "perceptual modulation" difficulties, whereas component N1 suppression was more closely related to "over-inclusion" of irrelevant sounds into the focus of attention. These findings suggest that the ERP components investigated are not redundant, but correspond to distinct-possibly related-pre-attentive processing systems.

Acoustic Stimulation↗

PubMed2003

Mismatch negativity in detection of interval duration deviation in schizophrenia.

Temporal processing deficits have been noted in behavioral studies assessing patients with schizophrenia. The current study sought to explore the physiology of temporal perception while controlling the effects of motivation, attention and other cognitive processes that may contribute to behavioral measures of temporal processing. Mismatch negativity (MMN) waveforms were measured in response to variations in the temporal parameters of an ongoing train of pure tones. A standard inter-stimulus interval of 400 ms was interrupted, on average, every 20th tone by an inter-stimulus interval of 340 ms. Amplitude of MMN waveform elicited by the temporal deviance was significantly reduced in the schizophrenia group compared with controls (p = 0.016). Results suggest that behavioral difficulties on time processing tasks in schizophrenia may reflect a physiological deficit in temporal perception in this population rather than simply more general difficulties in attention or motivation.

Adult↗

PubMed2003

Early postnatal development of sensory gating.

Sensory gating represents the nervous system's ability to inhibit responding to irrelevant environmental stimuli. In order to characterize the early development of acoustic sensory gating, suppression of auditory evoked potential component P1 (i.e. P50) in response to paired clicks was measured during REM sleep in healthy infants (1-4 months) that were without genetic risk for disrupted sensory gating function (i.e. having a relative with schizophrenia). As a group, the subjects exhibited significant response suppression. A correlation between increasing age and stronger response suppression was uncovered, even within this restricted age range. Parallel changes in sleep physiology could not be ruled out as the explanation for this change. Nevertheless, these results demonstrate that the neural circuits underlying sensory gating are functional very early in postnatal development.

Acoustic Stimulation↗

PubMed2003

Effects of interval duration on temporal processing in schizophrenia.

INTRODUCTION: Temporal processing has received scant attention in the literature pertaining to cognitive deficits in patients with schizophrenia. Previous research suggests that patients with schizophrenia exhibit temporal perception deficits on both auditory and visual stimuli. The current study investigated the effects of interval manipulation to (1) replicate the original findings with a larger sample and an increased number of trials (2) assess the degree to which both patients and controls can differentiate temporal changes in a range of experimental interstimulus intervals, and (3) explore whether different interstimulus interval durations pose different levels of difficulty for the patients with schizophrenia. METHODS: Participants were asked to decide whether temporal intervals were shorter or longer than standard intervals on a computer-based auditory temporal perception task. The standard interval remained the same duration throughout the various tasks. The interstimulus interval separating the standard and experimental intervals varied in the range of 500, 1000, or 3000 ms. Data are presented for a sample of 16 patients with schizophrenia and 15 controls. RESULTS: Data suggest that patients with schizophrenia exhibit deficits in differentiating interval durations across all paradigms compared to their control-group peers on a range of auditory tasks (p<.001). CONCLUSIONS: These results are consistent with a general temporal deficit in schizophrenia. However, the roles of medication and localization are also addressed.

Adult↗

PubMed2003

Sensory gating impairment associated with schizophrenia persists into REM sleep.

Physiological measures of sensory gating are increasingly used to study biological factors associated with attentional dysfunction in psychiatric and neurologic patient populations. The present study was designed to assess sensory gating during rapid eye movement (REM) sleep in patients with schizophrenia, a population bearing a genetic load for gating impairment. Auditory event-related potentials (ERPs) were recorded in response to paired clicks during separate waking and overnight sleep recording sessions in controls and schizophrenia patients. Suppression of ERP component P50 was significantly impaired in the patient group during both waking and REM sleep, whereas the difference between groups for N100 gating was dependent on state. These results suggest that REM sleep is an appropriate state during which to assess P50 gating in order to disentangle the effects of state and trait on sensory gating impairment in other clinical populations.

Acoustic Stimulation↗

PubMed2002

Deficits in auditory and visual temporal perception in schizophrenia.

INTRODUCTION: Characteristics of time perception have not been well documented in patients with schizophrenia. The current study investigated time estimation to (1) test whether visual and auditory time perception varied between patients and controls, (2) assess the degree to which patients and controls can differentiate changes in experimental intervals, and (3) explore whether the temporal deficits suggest a general time perception deficit versus modality-specific differences. METHODS: Participants were asked to decide whether temporal intervals were shorter or longer than standard intervals on computer-based auditory and visual temporal perception tasks. Data are presented for a sample of 10 patients with schizophrenia and 10 normal controls. RESULTS: Data suggest that patients with schizophrenia exhibit deficits in differentiating subtle differences in intervals in the tens of milliseconds range, compared to their normal control peers on both auditory (p < .01) and visual perception tasks (p < .01). CONCLUSIONS: Preliminary data suggest that there is a general temporal processing deficit in schizophrenia. However, future research using complementary techniques may provide useful information regarding the specific types of temporal deficits that affect patients with schizophrenia and the physiology of the dysfunction.

Journal Article↗