A Computational Model of Emotional Influences on Visual Working Memory Related Neural Activity

1. fMRI results detection memory Simulated BOLD responses DLPFC detection task memory task DLPFC OFC OFC Schematic outline of the model Working Memory • Separable brain structure for maintenance or emergent property of recurrent interactions between neural areas? • Implicated brain sites: • PFC • Inferior temporal cortex • VAC • Parietal cortex • These areas are also often associated with attentional processing. Table of weights Omitted connections are either 1 or nonexistent. Order of differential weights is U-N-P. A Computational Model of Emotional Influences on Visual Working Memory Related Neural Activity Nienke Korsten Nikos Fragopanagos John Taylor ABSTRACT - We analyze the interaction between emotion and cognition in terms of a simulation of the inhibitory interaction observed between the orbito-frontal cortex and the dorso-lateral prefrontal cortex while subjects are processing pictures of various levels of emotional valence. The CODAM attention framework is used to simulate the cognitive character, and in addition amygdala activation is used as a further bias of attention. Good agreement with observations is obtained. Model Based on CODAM model in which attention is created by ‘attention movement control signal’ generated by IMC. 3 dedicated nodes per module, representing pleasant, neutral and unpleasant stimuli. Lateral inhibition between nodes in object map, exogenous goals, corollary discharge and IMC modules. Input module: node has activation of 1 when corresponding stimulus is presented in paradigm, 0 otherwise. Other single nodes consist of graded neurons with a sigmoid response function and no internal structure. X in schematic outline represents multiplicative modulation, causing attentional amplification in object map by IMC. Paradigm Abbreviations Perlstein, Elbert & Stenger (2002) BOLD CODAM bla DLPFC IMC OFC PFC VAC WM Blood Oxygen Level Dependent Corollary Discharge of Attention Movement Dorsolateral prefrontal cortex Inverse Model Controller Orbitofrontal cortex Prefrontal cortex Visual Association Cortex Working Memory 0 - 2.5 s Presentation of unpleasant, neutral or pleasant stimulus Memory task: Subject is required to remember stimulus Memory task: Assessment if probe is equal to remembered cue Detection task: Comparison of two pictures within probe Conclusions 2.5 - 14 s With the current model, we have suggested an account of WM as an emergent property of recurrent interactions between the DLPFC and sensory areas, influenced by emotional stimuli via the amygdala and OFC. This account agrees with fMRI data as presented by Perlstein et al (2002). 14 s Emotional Influences on WM Outstanding Questions Analogous neural sites • Dolcos & McCarthy find that emotional distracters during delay period in visual WM task • deactivate DLPFC and parietal cortex • activate amygdala and ventrolateral PFC • Similarly, in the Perlstein paradigm there is an inverse relationship between DLPFC and OFC activation, indicating a mutual inhibition between these two structures No agreement with some aspects of behavioral data. Is DLPFC accurate site of stimulus – probe matching? Attentional model applied to WM: is distraction caused by attentional mechanism? GOALS IMC / Corollary Discharge Obj Map / Sensory WM MFC Parietal areas VAC Handout References Dolcos, F. and McCarthy, G. (2006) "Brain systems mediating cognitive interference by emotional distraction," Journal of Neuroscience26(7) 2072-2079 Fragopanagos, N., Kockelkoren, S., and Taylor, J. G. (2005) "A neurodynamic model of the attentional blink," Cognitive Brain Research24(3) 568-586 Korsten, N., Fragopanagos, N., Hartley, M., Taylor, N. and Taylor, J.G. (2006) “Attention as a Controller” Neural Networks In Press Perlstein, W. M., Elbert, T., and Stenger, V. A. (2002) "Dissociation in human prefrontal cortex of affective influences on working memory-related activity," PNAS99(3) 1736-1741 Taylor, J. G. (2000) "Attentional Movement: the Control Basis for Consciousness," Abstracts of the Society of Neuroscience26 2231 (#839.3) Taylor, J. G. (2005) "Mind and consciousness: Towards a final answer?," Physics of Life Reviews2(1) 1-45 This research was supported by UK (NF) EC cognitive robot project (JT) EC Network of Excellence (NK) CNS Group Dept. of Mathematics