Search results for "MISMATCH NEGATIVITY"
showing 10 items of 182 documents
Perinatal cerebral insults alter auditory event-related potentials.
2011
Background: Auditory event-related potentials (AERPs) can be used as indices of neural information processing. Altered AERPs have been reported in children and young adults with frontal lobe infarction. Aim: To test the hypothesis that perinatal brain injury affects cortical auditory processing. Methods: We assessed AERPs at term. 6 and 12 months of age in preterm infants [n = 9. median gestational age (GA) 27.9, range 23.9-30.0 wk], term infants with perinatal intracerebral hemorrhage (ICH) [n = 5, GA 40.3, range 37.4-42.3 wk], and term infants with perinatal asphyxia In [n = 4. GA 39.4. range 37.9-40.3 wk]. Healthy preterm (n = 16) and term infants (n = 22) served as controls. A harmonic …
Patients with minimal hepatic encephalopathy show impaired mismatch negativity correlating with reduced performance in attention tests
2012
Attention deficit is an early event in the cognitive impairment of patients with minimal hepatic encephalopathy (MHE). The underlying mechanisms remain unclear. Mismatch negativity (MMN) is an auditory event-related potential that reflects an attentional trigger. Patients with schizophrenia show impaired attention and cognitive function, which are reflected in altered MMN. We hypothesized that patients with MHE, similarly to those with schizophrenia, should show MMN alterations related with attention deficits. The aims of this work were to assess whether (1) MMN is altered in cirrhotic patients with MHE, compared to those without MHE, (2) MMN changes in parallel with performance in attentio…
Precursors of the evoked K-complex in event-related brain potentials in stage 2 sleep.
1997
The aim of the study was to examine precursors of the evoked K-complex as manifested in event-related brain potentials (ERPs) during stage 2 sleep. ERPs to infrequent deviant tones of 1100 and 2000 Hz and immediately preceding frequent standard tones of 1000 Hz were compared between trials containing and trials not containing a K-complex (KC trials, NO KC trials, respectively) to the deviant tones. The N350 wave to the deviant tones was markedly larger during the KC than during the NO KC trials. Also the P210 wave to the 2000 Hz deviant tone showed the same phenomenon. No definite evidence was found for the mismatch negativity-like deflection during the KC trials. ERPs to the standard tones…
Are different kinds of acoustic features processed differently for speech and non-speech sounds?
2001
This study examined how changes in different types of acoustic features are processed in the brain for both speech and non-speech sounds. Event-related potentials (ERPs) were recorded in native Finnish speakers presented with sequences of repetitive vowels (/e/) or complex harmonical tones interspersed with infrequent changes in duration, frequency and either a vowel change (/o/ for vowel sequences) or a double deviant (frequency+duration change for tone sequences). The stimuli were presented monaurally in separate blocks to either the left or right ear. The results showed that speech stimuli were more efficiently processed than harmonical tones as reflected by an enhanced mismatch negativi…
To switch or not to switch: Brain potential indices of attentional control after task-relevant and task-irrelevant changes of stimulus features
2009
Attention is controlled by the interplay of sensory input and top-down processes. We compared attentional control processes during task switching and reorientation after distraction. The primary task was to discriminate laterally and centrally presented tones; these stimuli were composed of a frequent standard or an infrequent deviant pitch. In the distraction condition, pitch was irrelevant and could be ignored. In the switch condition, pitch changes were relevant: whenever a deviant tone was presented, participants had to discriminate its pitch and not its direction. The task in standard trials remained unchanged. In both conditions, deviants elicited mismatch negativity (MMN), P3a, P3b, …
Behavioral and event-related potential distraction effects with regularly occurring auditory deviants
2007
When auditory stimulation contains infrequent task-irrelevant changes (deviants), behavioral responses to task-relevant aspects of the stimulation are prolonged. Event-related brain potentials (ERPs) show that deviants elicit mismatch negativity (MMN), P3a, and reorienting negativity (RON). Here, we examine whether distraction effects can also be elicited within fixed auditory sequences with deviant probabilities of 0.25, 0.33, and 0.5. Deviants varied either in pitch, loudness, or sound source location. In all conditions MMN and P3a were elicited, suggesting that an automatic detection of and an attentional allocation to the change occurred. With relative frequencies of 25% and 33%, devian…
Response repetition vs. response change modulates behavioral and electrophysiological effects of distraction
2004
If stimulation occasionally contains distracting information, behavioral responses to task-relevant aspects of the stimulation are prolonged and more error prone. Additionally, event-related potentials (ERPs) acquired in an auditory distraction paradigm show that the distracting information elicits the components mismatch negativity (MMN), P3a and reorienting negativity (RON). Here, we assess to what extent sequential dependencies in the stimulation influence such indicators of distraction. Data of four experiments were reanalyzed for response repetition and response change trials separately. Behavioral performance on Deviants suggests markedly smaller distraction effects in change compared…
Passive exposure to speech sounds modifies change detection brain responses in adults
2019
In early life auditory discrimination ability can be enhanced by passive sound exposure. In contrast, in adulthood passive exposure seems to be insufficient to promote discrimination ability, but this has been tested only with a single short exposure session in humans. We tested whether passive exposure to unfamiliar auditory stimuli can result in enhanced cortical discrimination ability and change detection in adult humans, and whether the possible learning effect generalizes to different stimuli. To address these issues, we exposed adult Finnish participants to Chinese lexical tones passively for 2 h per day on 4 consecutive days. Behavioral responses and the brain's event-related potenti…
Mismatch negativity during objective and subjective sleepiness.
1997
The mismatch negativity (MMN) and P3 of auditory event-related potentials were studied during subjectively and objectively (physiologically) defined sleepiness under optimal stimulus conditions for MMN elicitation. The MMN and P3 were elicited by either small or large unattended auditory deviants presented to the left ear. The participant's task was to detect either rare auditory targets presented to the right ear or rare changes in the light flashes. Eleven young adults served as participants in a nighttime experiment. The MMN declined especially at Fz and Cz but not so markedly at the right mastoid as either subjective or objective alertness decreased. The amplitude of P3 also decreased d…
Brain reacts to occasional changes in duration of elements in a continuous sound
1995
In order to study the event-related potential correlates of human ability to detect temporal changes within a continuous sound a sound consisting of two alternating pitches of the same constant duration, with infrequent shortenings of one of the tones, was presented to the subjects. The infrequent shortenings were found to elicit a negative component of the auditory event related potential, called the mismatch negativity (MMN). The experimental parameters were chosen to produce a MMN with a minimal contamination of N1, the main negative deflection of an evoked response with the same latency range as MMN and with a short experimental time. The duration of the whole experiment with three diff…