BRAIN ACTIVITY RELATED TO SERIAL COGNITIVE PERFORMANCE RESEMBLES CIRCUITRY OF HIGHER-ORDER MOTOR CONTROL

Differences between two states of cerebral activation were studied in eight subjects by positron emission tomography (PET) of regional cereb ral blood flow (rCBF) and subsequent statistical parameter mapping. Su bjects had to respond to a row of numbers presented on tape. In one co ndition they had to repeat each number. In the other condition the las t heard number had to be added to the number presented before. Cerebra l activity specifically related to the serial addition task was distri buted over supplementary motor area (SMA), left premotor cortex and su perior dorsal parietal cortex bilaterally, without significant involve ment of prefrontal cortex. This indicated circuitry related to mental performance characterised by a fixed strategy of executing serial mani pulation of numbers within ''internal space''. The main aim of this co mmunication is to discuss the similarity between circuitry underlying higher order motor control and pure cognitive performance.