title: Abnormalities of neuronal oscillations and temporal integration to low- and high-frequency auditory stimulation in schizophrenia.
abstract: BACKGROUND
  Electroencephalography and magnetoencephalography studies indicate among schizophrenia patients (SZ) abnormal, often reduced, entrained steady-state (aSSR) and transient (N100/M100) neural responses to auditory stimuli. We complement this literature by focusing analyses on auditory cortices, assessing a wide range of stimulation frequencies with long driving periods and evaluating relationships between aSSR and M100 reductions in SZ.
  
  
  METHODS
  Seventeen SZ and 17 healthy subjects (H) participated. Stimuli were 1500 msec binaural broadband noise sequences modulated at 5, 20, 40, 80, or 160 Hz. Magnetoencephalography data were collected and co-registered with structural magnetic resonance images. The aSSRs and M100s projected into brain space were analyzed as a function of hemisphere, stimulus density, and time.
  
  
  RESULTS
  For aSSR, SZ displayed weaker entrainment bilaterally at low (5-Hz) and high (80-Hz) modulation frequencies. To 40-Hz stimuli, SZ showed weaker entrainment only in right auditory cortex. For M100, while responses for H increased linearly with stimulus density, this effect was weaker or absent in SZ. A principal components analysis of SZ deficits identified low (5-Hz entrainment and M100) and high (40- to 80-Hz entrainment) frequency components. Discriminant analysis indicated that the low-frequency component uniquely differentiated SZ from H. The high-frequency component correlated with negative symptoms among SZ.
  
  
  CONCLUSIONS
  The SZ auditory cortices were unable to 1) generate healthy levels of theta and high gamma band (80-Hz) entrainment (aSSR), and 2) augment transient responses (M100s) to rapidly presented auditory information (an index of temporal integration). Only the latter was most apparent in left hemisphere and may reflect a prominent neurophysiological deficit in schizophrenia.
authors.affiliation: Department of Psychology and Neuroscience, BioImaging Research Center, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Jordan P
authors.initials: JP
authors.lastname: Hamm
authors.forename: Casey S
authors.initials: CS
authors.lastname: Gilmore
authors.forename: Natalie A M
authors.initials: NA
authors.lastname: Picchetti
authors.forename: Scott R
authors.initials: SR
authors.lastname: Sponheim
authors.forename: Brett A
authors.initials: BA
authors.lastname: Clementz
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001303:Auditory Cortex / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D016002:Discriminant Analysis; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008875:Middle Aged; D025341:Principal Component Analysis; D011571:Psychoacoustics; D012559:Schizophrenia / Q000473:pathology*; D055815:Young Adult