Effects of prior stimulus and prior perception on neural correlates of auditory stream segregation

Abstract

We examined whether effects of prior experience are mediated by distinct brain processes from those processing current stimulus features. We recorded event-related potentials (ERPs) during an auditory stream segregation task that presented an adaptation sequence with a small, intermediate, or large frequency separation between low and high tones (Deltaf), followed by a test sequence with intermediate Deltaf. Perception of two streams during the test was facilitated by small prior Deltaf and by prior perception of two streams and was accompanied by more positive ERPs. The scalp topography of these perception-related changes in ERPs was different from that observed for ERP modulations due to increasing the current Deltaf. These results reveal complex interactions between stimulus-driven activity and temporal-context-based processes and suggest a complex set of brain areas involved in modulating perception based on current and previous experience.

Loss and persistence of implicit memory for sound: Evidence from auditory stream segregation context effects

“…1 and 2, perceptual judgments during the test in Experiment 1 were influenced by Δƒ during the context, with larger prior Δƒ leading to less streaming, as compared with when a smaller Δƒ was presented, replicating previous findings Snyder et al, 2008;Snyder, Holder, et al, 2009;Snyder & Weintraub, 2011). The effect of context2 was larger than the effect of context1 (see Fig.…”

“…Similar to buildup, it is possible to explain the effect of prior Δƒ as resulting from adaptation of neurons tuned to large (or small) Δƒs, under the assumption that reduced responsiveness of neurons would cause greater relative responses in neurons tuned to Δƒ of the opposite size-that is, small (or large)-for which we have found some evidence using event-related potentials (Snyder, Holder, et al, 2009). However, an adaptation explanation does not account for the facilitative nature of the prior perception context effect.…”

“…Specifically, these studies have consistently found that listeners are more likely to report perceiving a test sequence as two separate streams when the preceding (or context) sequence contained a small Δƒ than when the context sequence contained a large Δƒ Snyder et al, 2008;Snyder, Holder, et al, 2009;Snyder & Weintraub, 2011). In addition to this contrastive effect of prior stimulation, a facilitative effect of prior judgment was also found, whereby listeners were more likely to report perceiving the test sequence as two separate streams if they had also reported perceiving the context sequence as two streams than if they had reported perceiving the context sequence as a single stream Snyder et al, 2008;Snyder, Holder et al, 2009). The facilitative effect of prior perception is dissociated from the prior Δƒ effect by measuring the prior perception effect when the Δƒ of the context and test are held constant, usually at an intermediate Δƒ level (e.g., five or six semitones).…”

“…It was also recently shown that the Δƒ of the previously presented sequence(s) and whether the listener perceived the previous sequence(s) as one stream or two have a major impact on subsequent perceptual judgments Snyder et al, 2008;Snyder, Holder, et al, 2009;Snyder & Weintraub, 2011). Specifically, these studies have consistently found that listeners are more likely to report perceiving a test sequence as two separate streams when the preceding (or context) sequence contained a small Δƒ than when the context sequence contained a large Δƒ Snyder et al, 2008;Snyder, Holder, et al, 2009;Snyder & Weintraub, 2011).…”

“…In the present study, we utilized recently discovered context effects in auditory scene analysis tasks (Snyder, Carter, Hannon, & Alain, 2009;Snyder, Carter, Lee, Hannon, & Alain, 2008;Snyder, Holder, Weintraub, Carter, & Alain, 2009;Snyder & Weintraub, 2011; see also Riecke, Mendelsohn, Schreiner, & Formisano, 2009;Riecke et al, 2011) to determine the extent to which implicit memories consist of memories that are lost versus persistent. Context effects in stream segregation have been demonstrated using sequences of tones organized into a repeating triplet pattern, ABA-ABA-.…”