Poster #: 17
Topic: Clinical applications (incl. consciousness)
Thursday, Sep 10, 2015
Complex pattern-deviant detection in schizophrenia
1Psychiatry, University of Pittsburgh, Pittsburgh, United States
The neural mechanisms that generate mismatch negativity (MMN) are debated, yet MMN is being assessed as a possible biomarker for schizophrenia (SZ). In SZ, MMN is smaller to stimulus deviants that differ in simple physical characteristics such as pitch. This suggests that auditory cortex is affected in SZ, but it is unclear whether it reflects deficits in stimulus adaptation, novelty detection, or both. MMN is also elicited by complex-pattern deviants, which cannot be due to non-adapted cells. We measured MMN to complex-pattern deviants to assess novelty detection in SZ and healthy controls (HC). Eight tones differing in 0.5 kHz steps were used in a standard zig-zag ascending pitch pattern (1, 2, 1.5, 2.5, 2, 3, 2.5, 3.5 kHz tones), with two final tone deviants: 2.5 kHz (repeat), or 4 kHz (jump). Subjects watched a silent video, and were presented with 80% standard patterns, 10% repeat- and 10% jump-deviants. HC (N=23) produced a late MMN-like negativity (400-500 ms after stimulus-onset) that was significantly larger than in SZ (N=23) to both the repeat (p=.038) and jump-deviant (p=.014). The topography and source of the activity was consistent with a typical MMN response. The MMN from a complex deviant cannot be argued to be due to adaptation because there was no repeated tone to drive adaptation, and the MMN was too late to be contaminated by a larger N1 response to novelty. SZ did not produce a late-MMN to the repeat- or the jump-deviant suggesting deficits in novelty detection.