Year-end Sale % OFF 
Abstract
To better understand sensory processing in frontal and parietal cortex of the rat, and to further assess the rat as a model of human frontal-parietal processing, we recorded local field potentials (LFPs) from microelectrode arrays implanted in medio-dorsal frontal, and posterior parietal cortex of awake rats as they were presented with a succession of frequent “standard” tones and infrequent “oddball” tones. Extending previous results from surface recordings we found, after controlling for the frequencies of the standard and oddball tones, that rat frontal and parietal-evoked LFPs (eLFPs) exhibit significantly larger N1 (~40 ms latency), P2 (~100 ms), N2 (~160 ms), P3E (~200–240 ms), and P3L (~300–500 ms) amplitudes after an oddball tone. These neural oddball effects could contribute to the automatic allocation of attention to rare stimuli. To determine whether these enhanced responses to rare stimuli could be accounted for in terms of stimulus-specific neural adaptation (SSA), we also recorded during single-tone control sessions involving frequent standard, or infrequent oddball beeps alone. We compared the difference between rare-tone and frequent-tone response amplitudes in the two-tone context (oddball effect) or single-tone context which isolates the contribution of SSA (SSA effect). An analysis of variance (ANOVA) revealed a significant main effect of tone context on rare-tone response enhancements, showing that the rare-tone enhancements were stronger in the two-tone context than the single-tone context. This difference between tone contexts was greatest at the early P3E peak (200–240 ms post-beep) in parietal cortex, suggesting true deviance detection by this evoked response component, which cannot be accounted for in terms of simple models of SSA.
Highlights
Rare auditory stimuli presented to human subjects evoke larger amplitude peaks in the average electro-encephalogram (EEG) response, known as the event-related potential (ERP), than more frequently presented tones (Wronka et al, 2008)
In order to study brain response enhancements to rare stimuli, local field potentials (LFPs) were recorded in medio-dorsal frontal and posterior parietal cortex while awake rats were exposed to sequences of tones, in two-tone “oddball” sessions and separately in single-tone “SSA” sessions designed to isolate the effect of stimulus-specific neural adaptation (SSA)
Since we are interested in the differential response to rare and frequent tones, rather than different obligatory responses to different pitches, the meaningful comparison is between the high-pitch oddball evoked LFPs (eLFPs) and the high-pitch standard eLFP
Summary
Rare auditory stimuli presented to human subjects evoke larger amplitude peaks in the average electro-encephalogram (EEG) response, known as the event-related potential (ERP), than more frequently presented tones (Wronka et al, 2008). This is known as an “oddball effect.”. The human P3 has been associated with cognitive processing such as comparisons in working memory (Polich, 2007) and even conscious perception (Del Cul et al, 2007) It is among the most reliably altered features of ERPs in neurological disorders (Pfefferbaum et al, 1989; Linden, 2005). Schizophrenic patients exhibited reduced P3 amplitudes in comparison to control subjects without the disorder (Pfefferbaum et al, 1989)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
