Drawing from memory in focal epilepsy: a cognitive and neural perspective

This study provides evidence of non-verbal cognitive functioning in temporal (TLE) and frontal lobe epilepsy (FLE) patients by exploring the mechanisms and neural correlates of drawing abilities. Sixty-six patients with left (n=32) or right TLE (n=34), 30 patients with left (n=18) or right FLE (n=12), and 30 healthy subjects were compared. The Drawing from Memory (DfM) test required participants to design 16 living or non-living items; the total score was the sum of all scores blindly provided by three judges who had to identify the drawings. The verbal and visual Pyramid and Palm Trees Test (PPTT), Raven Colored Progressive Matrices (Raven CPM), Cube Analysis, Token Test, Word Fluency, Card Classification, and Rey Complex Figure Test Copy trial (Rey CFC) assessed different verbal and non-verbal functions. Non-parametric statistics indicated that, with respect to controls, both TLE groups and the left FLE patients had significantly lower DfM scores. In the TLE group, hierarchical regression analyses revealed that the DfM score was predicted by the Raven CPM and PPTT scores, while, in the FLE group, it was predicted by the Rey CFC. Thus, drawing abilities may be impaired by TLE or FLE owing to different mechanisms that involve semantic or executive abilities. Implying cooperation between temporal and frontal areas that support these functions, DfM may be a sensitive index of integrity of cortical areas or neural pathways damaged by focal epilepsy.