Unit:
Specialty Cognitive NeuroscienceLibrary of the School of Health Sciences
Author:
Filippakopoulou Eugenia
Supervisors info:
Σμυρνής Νικόλαος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ, Επιβλέπων
Πόταγας Κωνσταντίνος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παπαγεωργίου Σωκράτης, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
The ''Cognitive Oblique effect'' and its neural substrate
Translated title:
The ''Cognitive Oblique effect'' and its neural substrate
Summary:
Previous studies have shown that visual direction reproduction results in two independent sources of anisotropy: a low level oblique effect, manifested in better accuracy in the reproduction of cardinal directions compared to oblique and a high level oblique effect, manifested in a distortion of directional space representation with space expansion around the cardinal directions and space contraction around the oblique directions. The low level oblique effect, known as ‘’visual’, is strictly confined to vision. The high level oblique effect, known as ‘’cognitive’’, is caused by a systematic directional error introduced by the cognitive process of space categorization. It increases with decreasing amount of directional information and is observed in different sensory modalities. Although neuroimaging and electrophysiological studies so far have focused on the visual oblique effect, little is already known about the neural correlate of the cognitive or high level oblique effect. In this experiment, we investigated the cortical activation pattern during an arrow alignment task using an event-related fMRI model at high field. Directional error was measured categorically when normal individuals tried to align the direction of an arrow towards a peripheral target located in one of 3 directions/target angles (vertical and 11.25 degrees left and right to that). Task difficulty was manipulated by varying target distance (0.7, 1.4 and 2.1 degrees visual angle), while the arrow length was kept constant (0.7 degrees visual angle).
We hypothesized that in the diagonal orientations the increasing target distance (decreasing amount of directional information) would result in activation of brain areas involved in higher cognitive processing. Whole brain analysis and following exploratory ROI analysis results showed: 1) a significant main effect of target distance observed in frontal, parietal, visual areas bilaterally and a gradual increase of BOLD response with the increase of target distance including all the clusters, 2) a significant effect of target angle on activation restricted in visual associative areas. In these areas a greater activation was observed for the diagonal directions compared to cardinal. 3) a significant interaction of target angle with target distance in right precuneus, left operculum, left superior temporal area and a brainstem region close to the right parahippocampal area. In the right precuneus, we showed a trend for higher activation with increasing task difficulty concerning only the diagonals. Our findings suggest a possible neural correlate of this oblique effect in brain areas involved in higher cognitive processing, in contrast to the classic oblique effect, which is represented in brain areas involved in primary visual processing.
Main subject category:
Health Sciences
Keywords:
Cognitive οblique effect, Space categorization, Directional Error, fMRI, Precuneus
