The use of forty hertz EEG as an index of information processing in the traumatically brain injured adult

by Woskosky, Robert

Gamma oscillations. in the fiequency range of 35-45 Hz and centered at 40 Hz have ken shown to be an index of ùiformation processing. perceptual binding and focused attention. People with traumatic brain injury (TBI) show poor performance on tests that require high levels of information processing and should therefore have correspondhg differences in the amount of 40 Hz EEG compared to controls. The purpose of this experiment was to find out whether there is a change in the arnount of 40 Hz EEG parallehg the scores that subjects obtained on tests of information processing. Moderate to severely damaged closed brain injury subjects and controls perfonned multiple trials of the written version of the Symbol Digit Modalities Test (SDMT) and a computer version of the test. EEG was collected during rest and testing conditions fkom 9 electrodes (F3. Fz F4. C3.Cz C4. P3. Pz and P4)placed according to the international 10-20 system of electrode placement. Root mean square power was calculated on the bandpass filtered range of 35-45 Hz for of 56 epochs. each 500 ms in length that were recorded for each trial. Statistics showed that as a group. patients differed significantly tiom controls on the m-rittenSDMT scores as well as the computer version. The EEG data were quite variable but suggest changes in 40 Hz pwer that were related to head injury and behavioural scores. although additional studies need to be done to confm this. The data also provide additional evidence that 40 Hz oscillations are an index of information processing in clinicai and control groups. " Be in love with yer life" ---Jack Kerouac