Localization of human cortical areas activated on perception of ordered and chaotic images

Abstract

The aims of this study were to identify the locations of areas in the human cortex responsible for describing fragmented test images of different degrees of ordering and to identify the areas taking decisions regarding stimuli of this type. The locations of higher visual functions were determined by functional magnetic resonance imaging (fMRI) using a scanner fitted with a superconducting magnet and a field strength of 1.5 T. The blood oxygen level-dependent (BOLD) method was based on measurements of the level of hemoglobin oxygenation in the blood supplied to the brain. This level was taken to be proportional to the extent of neuron activation in the corresponding part of the gray matter. Stimuli were matrixes consisting of Gabor elements of different orientations. The measure of matrix ordering was the ratio of the number of Gabor elements with identical orientations to the total number of elements in the image. Brain neurons were activated by simultaneous changes in the orientations of all the elements, leading to substitution of one matrix by another. Substitution of the orientation was perceived by observers as rotation of the elements in the matrix. Stimulation by matrixes with a high level of ordering was found to activate the occipital areas of the cortex, V1 and V2 (BA17-BA18), while presentation of matrixes with random element orientations also activated the parietal-temporal cortex, V3, V4, V5 (BA19), and the parietal area (BA7). Brain zones responsible for taking decisions regarding the level of order or chaos in the organization of the stimuli are located in different but close areas of the prefrontal and frontal cortex of the brain, including BA6, BA9, and BA10. The results are assessed in terms of concepts of the roles and interactions of different areas of the human brain during recognition of fragmented images of different degrees of complexity.

Lateralized neural mechanisms underlying the modulation of response inhibition processes

“…Fokin et al, 2008;Takeichi et al, 2010). The current results show that BA7 is less activated, when stimuli are presented to the language dominant left (the RVF), compared to the on-dominant right hemisphere (the LFV).…”

Somatosensory lateral inhibition processes modulate motor response inhibition - an EEG source localization study

“…Yet, opposed to medial frontal areas, the superior parietal cortex (BA7) has less frequently been reported to be involved in response inhibition 17, 32, 36, 37 . However, BA7 is involved in response inhibition whenever information is complex and probably difficult to categorize but essential for behavioral control 31–33 . This is also likely the case in the current study, and especially so in the between-hands condition, because information from both hands need to be integrated.…”

“…These parietal regions have already been shown to be involved in response inhibition processes using somatosensory stimuli 11 . Moreover, they are involved during sensorimotor integration 29, 30 , also during response inhibition when sensory information is difficult to categorize but essential for behavioral control 31–33 . This may be the case due to the effects of lateral inhibition.…”

Insulin Modulates Food-Related Activity in the Central Nervous System

“…Both studies therefore support our notion of insulin-specific reduction in brain activity. Other regions affected by insulin include cortical frontal and temporal areas, which are involved in object recognition and decision making (29,33). The involvement of the hippocampus in food-specific processing is well established, and Pelchat et al (32) showed that this structure is especially involved in food craving.…”