Deriving Numerosity and Shape from Identical Visual Displays

• Published in: NeuroImage (Orlando, Fla.) Vol. 13; no. 1; pp. 46 - 55
• Main Authors: Fink, Gereon R., Marshall, John C., Gurd, Jennifer, Weiss, Peter H., Zafiris, Oliver, Shah, Nadim J., Zilles, Karl
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2001; Elsevier Limited
• Subjects: Adult; Attention - physiology; attentional modulation; Brain - physiology; Cerebral Cortex - physiology; Cognition - physiology; Cortex (cingulate); Cortex (frontal); directed attention task; Enumeration; Experiments; Eye Movements - physiology; Female; fMRI; Form Perception - physiology; Functional magnetic resonance imaging; Humans; Information processing; Magnetic Resonance Imaging; Male; Neuroimaging; Photic Stimulation; Prefrontal cortex; Prefrontal Cortex - physiology; Reaction Time - physiology; serial/parallel processing; spatial binding; subitizing; Visual cortex; Visual Cortex - physiology; fMRI; attentional modulation; serial/parallel processing; directed attention task; spatial binding; subitizing
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1006/nimg.2000.0673

We presented identical displays of three to five dots in a functional magnetic resonance imaging (fMRI) experiment with normal volunteers. Two distinct directed attention tasks were performed on these displays: In one condition, subjects assessed the numerosity of the display; in the other condition, they assessed the shape of the display. Decisions based on numerosity activated differentially striate and extrastriate visual processing areas as well as left inferior frontal cortex. Decisions based on shape derived from arrangement activated differentially temporoparietal cortex bilaterally, medial posterior cingulate cortex, and left dorsolateral prefrontal cortex. These divergent neural activations in response to identical stimuli suggest that attentional mechanisms are deployed in very different ways in rapid enumeration of visual objects and in linking spatially discrete elements to one form.