title: Mapping mental calculation systems with electrocorticography.
abstract: OBJECTIVE
  We investigated intracranially-recorded gamma activity during calculation tasks to better understand the cortical dynamics of calculation.
  
  
  METHODS
  We studied 11 patients with focal epilepsy (age range: 9-28years) who underwent measurement of calculation- and naming-related gamma-augmentation during extraoperative electrocorticography (ECoG). The patients were instructed to overtly verbalize a one-word answer in response to auditorily-delivered calculation and naming questions. The assigned calculation tasks were addition and subtraction involving integers between 1 and 17.
  
  
  RESULTS
  Out of the 1001 analyzed cortical electrode sites, 63 showed gamma-augmentation at 50-120Hz elicited by both tasks, 88 specifically during naming, and 7 specifically during calculation. Common gamma-augmentation mainly took place in the Rolandic regions. Calculation-specific gamma-augmentation, involving the period between the question-offset and response-onset, was noted in the middle-temporal, inferior-parietal, inferior post-central, middle-frontal, and premotor regions of the left hemisphere. Calculation-specific gamma-augmentation in the middle-temporal, inferior-parietal, and inferior post-central regions peaked around the question offset, while that in the frontal lobe peaked after the question offset and before the response onset. This study failed to detect a significant difference in calculation-specific gamma amplitude between easy trials and difficult ones requiring multi-digit operations.
  
  
  CONCLUSIONS
  Auditorily-delivered stimuli can elicit calculation-specific gamma-augmentation in multiple regions of the left hemisphere including the parietal region. However, the additive diagnostic value of measurement of gamma-augmentation related to a simple calculation task appears modest.
  
  
  CONCLUSIONS
  Further studies are warranted to determine the functional significance of calculation-specific gamma-augmentation in each site, and to establish the optimal protocol for mapping mental calculation.
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, MI 48201, USA.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Psychiatry and Behavioral Neurosciences and MD-PhD Program, Wayne State University, School of Medicine, Detroit, MI 48201, USA.
authors.forename: Erik C
authors.initials: EC
authors.lastname: Brown
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, MI 48201, USA.
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Kojima
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, MI 48201, USA; Department of Neurology, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, MI 48201, USA.
authors.forename: Csaba
authors.initials: C
authors.lastname: Juhász
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, MI 48201, USA; Department of Neurology, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, MI 48201, USA. Electronic address: eishi@pet.wayne.edu.
authors.forename: Eishi
authors.initials: E
authors.lastname: Asano
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D002648:Child; D004569:Electroencephalography / Q000379:methods*; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D010296:Parietal Lobe / Q000502:physiology*; D013850:Thinking / Q000502:physiology*; D055815:Young Adult
keywords: Angular gyrus; Auditory; Cognition; Event-related synchronization; Functional brain mapping; Intracranial ECoG recording; Language; Number; Numeral; Pediatric epilepsy surgery; Physiological high-frequency oscillations (HFOs); Ripples; Spatio-temporal-dynamics; Speech; Subdural EEG; Time-frequency analysis