Topographical representations of mental images in primary visual cortex

Abstract

We report here the use of positron emission tomography (PET) to reveal that the primary visual cortex is activated when subjects close their eyes and visualize objects. The size of the image is systematically related to the location of maximal activity, which is as expected because the earliest visual areas are spatially organized. These results were only evident, however, when imagery conditions were compared to a non-imagery baseline in which the same auditory cues were presented (and hence the stimuli were controlled); when a resting baseline was used (and hence brain activation was uncontrolled), imagery activation was obscured because of activation in visual cortex during the baseline condition. These findings resolve a debate in the literature about whether imagery activates early visual cortex and indicate that visual mental imagery involves 'depictive' representations, not solely language-like descriptions. Moreover, the fact that stored visual information can affect processing in even the earliest visual areas suggests that knowledge can fundamentally bias what one sees.

Functional Evaluation of Hidden Figures Object Analysis in Children with Autistic Disorder

“…Consistent with the findings of Ring et al (1999), subjects with autism in the present study demonstrated greater activity in right occipital cortex, which is involved in the visual processing of objects (Kosslyn et al 1995), extending into the inferior temporal region (Ring et al 1999). The occipital, inferior temporal, and inferior parietal activity observed is also consistent with the activation patterns in adults with AD (Baron-Cohen et al 1994) and implicates spatial visual processing pathways (Ungerleider et al 1998).…”

Logic, language and the brain

“…", Goel and Dolan, 2001;Knauff et al, 2003;Prado et al, 2010b). To illustrate the impact of these distinctions on brain activations, relational problems may recruit posterior parietal regions (e.g., Goel and Dolan, 2001;Knauff et al, 2003) that are known to underlie the kind of spatial representation evoked by transitive relations like "taller than" (Kosslyn et al, 1995;Prado et al, 2010b). Such regions would not be expected for connectives, which seem devoid of spatial interpretation.…”

The frontal eye field as a prediction map

“…When a subject is asked to ''imagine'' a particular image the frontal lobes invariably come on line. Feedback connections from the frontal lobes to the posterior lobes are thought to activate the same circuits that would be activated if the actual image had been presented to the retinas (Kosslyn et al, 1995). Furthermore, the eye movements of subjects asked to imagine a particular scene reflect the content and spatial arrangement of objects populating the scene (Mast and Kosslyn, 2002).…”