Rapid Interactions between the Ventral Visual Stream and Emotion-Related Structures Rely on a Two-Pathway Architecture

Tested models. a, Basic components of the generic model, including all the possible types of connections used in this report, within and between two connected regions. Top, Cortical regions are modeled as three layered columns with three types of neuronal populations (pyramidal, excitatory spiny, and inhibitory interneurons), connected through intrinsic and extrinsic (feedforward and backward) connections. Bottom, The dynamics is mathematically expressed at the level of neural populations and is defined by nonlinear differential equations in which the change of state of each unit dx_i/dt depends on its current state xⁱ(t); thalamic inputs uⁱ(t); average firing rate of afferents S(x^j(t − δ^ij)); transmission delays δ^ij; forward, backward, and intrinsic effective connectivity matrices C^F, C^B, Cⁱ, and other parameters. The MEG signal M is assumed to be related to the local average current density x generated by pyramidal populations through a linear forward model M = GX (David et al., 2006). b, Lateral, mesial, and ventral views of the mapping of the regions of interest common to all models on a reference cortical tessellation [for color code, see text and c (top row)]. c, Schematic representation of the architecture of the tested models. All the models share the same basic layout (see text). Null model, Simple feedforward model. Model 1, Adjunction of connectivity modulation. Model 2 (2-stage model), Adjunction of local feedbacks. Model 3 (2-stage model), Adjunction of long-range feedbacks from structures of the AAS. Model 4 (2-pathway model), Adjunction of a direct subcortical retinotectal short-cut pathway to the AAS. Model 5 (2-pathway model), Alternative short-cut pathways to the AAS via the inferior longitudinal and frontal–occipital fasciculi. Model 6 (2-pathway model), Combination of models 4 and 5. Orange circles, “Synapses” at which modulation by emotional competence of the stimuli is implemented.

Basic MEG results. a, MEG evoked response averaged across stimulus and across subjects (n = 15) per category. b, Cortical noise normalized minimum-norm source reconstruction results averaged across subjects and thresholded above three SDs above baseline for each category. The results show an overall propagation of activity from early visual cortices to frontal regions through the temporal lobes, with indication of early responses in the OFC for unpleasant and pleasant stimuli. c, Thresholded minimum-norm results for the contrast between pleasant and neutral stimuli on slightly unfolded cortical surfaces. Effects are reconstructed in occipital and temporal regions, in the temporal pole and the OFC (early and late). Similar but less extended effects were found with unpleasant stimuli (see supplemental Fig. 1, available at www.jneurosci.org as supplemental material).