ARTICLE UPDATE - Dissociated responses in the amygdala and orbitofrontal cortex to bottom-up and top-down components of emotional evaluation.

Wright P, Albarracin D, Brown RD, Li H, He G, Liu Y.

NeuroImage, in press

Although emotional responses to stimuli may be automatic, explicit evaluation of emotion is a voluntary act. These bottom-up and top-down processes may be supported by distinct neural systems. Previous studies reported bottom-up responses in the amygdala, top-down responses in the orbital and ventromedial prefrontal cortices, and top-down modulation of the amygdalar response. The current study used event-related fMRI on fifteen healthy males to examine these responses in the absence of stimulus anticipation or task repetition. Factorial analysis distinguished bottom-up responses in the amygdala from top-down responses in the orbitofrontal cortex. Activation of ventromedial prefrontal cortex and modulation of amygdalar response were not observed, and future studies may investigate whether these effects are contingent upon anticipation or cognitive set.

ARTICLE UPDATE - Top-down predictions in the cognitive brain.

Kveraga K, Ghuman AS, Bar M.

Brain and Cognition, in press (not available online yet for unknown reason)

The human brain is not a passive organ simply waiting to be activated by external stimuli. Instead, we propose that the brain continuously employs memory of past experiences to interpret sensory information and predict the immediately relevant future. The basic elements of this proposal include analogical mapping, associative representations and the generation of predictions. This review concentrates on visual recognition as the model system for developing and testing ideas about the role and mechanisms of top-down predictions in the brain. We cover relevant behavioral, computational and neural aspects, explore links to emotion and action preparation, and consider clinical implications for schizophrenia and dyslexia. We then discuss the extension of the general principles of this proposal to other cognitive domains.