Generalised script sequencing deficits following frontal lobe lesions

Neuropsychological investigations have consistently shown that frontal cortices are relevant in processing temporal and sequential features of actions. However, one of the main theoretical issues that has been discussed in the last 25 years is whether these brain areas store some abstract representations of actions or, conversely, act upon action representations stored within other posterior associative cortices. We administered to 19 patients with frontal lobe lesions and 19 normal controls, script sequencing and generating tasks concerning actions, natural events and “époques” (ordered events such as the days of the week). The main findings from frontal lobe patients were a generalised sequencing deficit concerning actions and natural phenomena (and not what we labelled “époques”) with almost intact ability to verbally generate, from the long-term memory, scriptsʹ sequences. These findings are discussed within two of the main theoretical frameworks on frontal lobes: the “processing” perspective of the Supervisory Attentional System, SAS (Norman and Shallice, 1986) and the “representational” one represented by the Structure Event Complex (SEC) theory (Grafman, 2002).