Development and topography of auditory event-related potentials (ERPs): Mismatch and processing negativity in individuals 8-22 years of age

Introduction: How do ERPs reflecting auditory information processing develop across adolescence? This development is described for the amplitude and latency of five ERP components and four difference-waves in four groups of 11 healthy subjects with mean ages of 10, 14, 17 & 21 years. Methods: Vector normalised data were recorded from 19 sites during diffuse and focused attention in a three-tone oddball. (i.e. in passive, diffuse-attention and active, focussed-attention, discrimination conditions) to see how ERP loci varied with age for tone-type, attention-condition and for four types of difference-wave reflecting nontarget and target comparisons: (mismatch negativity, MMN, an auditory working memory trace; Negative difference, Nd, an attentional trace, but also Processing Negativity, PN and the Goodin-waveform). Results: Age interacted with site for most components. P1 loci sensitive to rare tones moved posteriorly and N1 loci lost their right bias at early puberty. But P2 loci did not move anterior to Cz until adulthood. N2 amplitude, sensitive to attention condition, developed a mature frontal focus by 17 years. Right-biased P3 loci move to the midline with focused attention in young and old alike. Difference-waves reflected three developmental stages (figure 2): In 10 year-olds early deflections (<150 ms) were diffusely distributed; in mid-adolescence the main frontal negative component (150-300 ms) became well-formed and lost an earlier right bias; over 17 years the late positive complex developed a right bias in target-derived waves. Latency decreases for early frontal components were marked in 10-14y olds and for later posterior components in 14-17y olds. MMN topography matured (from a right lateral to bilateral distribution) between 10 and 14 y, while Nd topography matured and became bilateral between 14 and 17y. Conclusions: Major developments of brain function appear at the onset of adolescence (<14y) in early stimulus-selection processes and during adolescence in the differential use of this information (N2- and P3-like latencies

Impaired attention-dependent augmentation of MMN in nonparanoid vs paranoid schizophrenic patients: a comparison with obsessive-compulsive disorder and healthy subjects

Introduction: Mismatch negativity (MMN), in the deviant-minus-standard event-related potential (ERP) difference-waveform, may represent a working memory trace for tone differences (a deviant among a sequence of standards). Most, but not all studies find MMN reduced in patients with schizophrenia. Aims: This report investigates if differences may be attributable to experimental condition (diffuse vs focused attention), component identification (N1-like vs N2-like), topographic distribution and clinical condition (with / without paranoid -hallucinatory symptoms, PH/NP). Comparisons were made for 12 PH and 12 NP schizophrenic patients with 13 obsessive compulsive and 25 normal control subjects. Results: Frontal MMN reduction in schizophrenics largely resulted from an absence of an increase in focused attention conditions as in comparison groups. But there was marked activity recorded from sites over the temporal lobe in NP patients. These features were not reflected in other components except for a visible but nonsignifiant N1-like temporal locus in NP patients. Further, schizophrenic patients did not show an increase in late positivity with focused attention like the comparison groups. Conclusions: The results show that so-called automatic processing deficits in schizophrenia (amount and locus of MMN) are best seen in situations requiring the activation of controlled attentional processes. It is suggested that impaired processing of irrelevant stimuli and reduced frontal MMN in NP patients may reflect reduced dopaminergic responsivity

Event-related potentials during an auditory discrimination with prepulse inhibition in patients with schizophrenia, obsessive-compulsive disorder and healthy subjects

Introduction: Prepulse inhibition (PPI) is a measure of the influence of a stimulus (S1) on the response elicited by a second stimulus (S2) occurring shortly afterwards. Most S1/S2 measures of gating have used behavioral startle and the P50 event-related potential (ERP) amplitudes to detect PPI in a simple paired stimulus paradigm. Aims: Here we report on two behavioral (EOG and reaction time, RT) and 5 ERP measures of PPI where S2 was the target or standard in an oddball discrimination. Subjects were 21 healthy controls (CON), 11 obsessive-compulsive (OCD) and 9 schizophrenic patients (SCH). Results: The prepulse 100ms before S2 induced fewer omission errors and longer RTs compared to a 500ms S1-S2 interval in all subjects. PPI was also evident in EOG, P50, N1, P3 but not P2 or N2 amplitudes of CON subjects. SCH patients showed attenuation of PPI on the same measures. OCD patients were characterized only by their slow RT and a marginal attenuation of EOG-PPI. Discussion: A correlational analysis implied separate relationships of ERP indices of PPI to the cognitive and psychomotor consequences of the prepulse on behavioral and discrimination responses. However SCH patients showed a general rather than a specific impairment of these indices

Auditory target processing in methadone substituted opiate addicts: The effect of nicotine in controls-1

<p><b>Copyright information:</b></p><p>Taken from "Auditory target processing in methadone substituted opiate addicts: The effect of nicotine in controls"</p><p>http://www.biomedcentral.com/1471-244X/7/63</p><p>BMC Psychiatry 2007;7():63-63.</p><p>Published online 6 Nov 2007</p><p>PMCID:PMC2198909.</p><p></p>tant non-opioid use and in control subjects with and without nicotine use