Functional asymmetry and interhemispheric cooperation in the perception of emotions from facial expressions

Abstract

The present study used the redundant target paradigm on healthy subjects to investigate functional hemispheric asymmetries and interhemispheric cooperation in the perception of emotions from faces. In Experiment 1 participants responded to checkerboards presented either unilaterally to the left (LVF) or right visual half field (RVF), or simultaneously to both hemifields (BVF), while performing a pointing task for the control of eye movements. As previously reported (Miniussi et al. in J Cogn Neurosci 10:216-230, 1998), redundant stimulation led to shorter latencies for stimulus detection (bilateral gain or redundant target effect, RTE) that exceeded the limit for a probabilistic interpretation, thereby validating the pointing procedure and supporting interhemispheric cooperation. In Experiment 2 the same pointing procedure was used in a go/no-go task requiring subjects to respond when seeing a target emotional expression (happy or fearful, counterbalanced between blocks). Faster reaction times to unilateral LVF than RVF emotions, regardless of valence, indicate that the perception of positive and negative emotional faces is lateralized toward the right hemisphere. Simultaneous presentation of two congruent emotional faces, either happy or fearful, produced an RTE that cannot be explained by probability summation and suggests interhemispheric cooperation and neural summation. No such effect was present with BVF incongruent facial expressions. In Experiment 3 we studied whether the RTE for emotional faces depends on the physical identity between BVF stimuli, and we set a second BVF congruent condition in which there was only emotional but not physical or gender identity between stimuli (i.e. two different faces expressing the same emotion). The RTE and interhemispheric cooperation were present also in this second BVF congruent condition. This shows that emotional congruency is the sufficient condition for the RTE to take place in the intact brain and that the cerebral hemispheres can interact in spite of physical differences between stimuli.

The motor side of emotions: investigating the relationship between hemispheres, motor reactions and emotional stimuli

“…This result is consistent with the right hemisphere hypothesis, which posits that this brain half is characterized by an overall superiority for emotional cues, independent of their valence (Alves, Aznar-Casanova, & Fukusima, 2009;Christman & Hackworth, 1993;Dimberg & Petterson, 2000;Hugdahl et al, 1993;McLaren & Bryson, 1987;Moreno et al, 1990;Narumoto, Okada, Sadato, Fukui, & Yonekura, 2001;Rodway & Schepman, 2007;Sato, Kochiyama, Yoshikawa, Naito, & Matsumura, 2004;Tamietto et al, 2006). However, if these results are diVerentiated according to valence and visual hemiWeld, the overall pattern changes.…”

“…It posits that emotional processing of both positive and negative emotions is lateralized toward the right hemisphere (Borod, 1992;Borod, Bloom, Brickman, Nakhutina, & Curko, 2002). Numerous studies have supported this hypothesis (Borod, Kent, KoV, Martin, & Alpert, 1988;Christman & Hackworth, 1993;Hugdahl, Iversen, & Johnsen, 1993;McLaren & Bryson, 1987;Moreno, Borod, Welkowitz, & Alpert, 1990;Tamietto, Latini Corazzini, de Gelder, & Geminiani, 2006). The second theory is the "valence hypothesis", which states that hemispheres diVer according to emotional valence with the right brain dominant for the processing of negative emotions and the left brain dominant for the processing of positive emotions (Davidson, 1995;Silberman & Weingartner, 1986).…”

Neural bases of the non-conscious perception of emotional signals

“…more positive or more negative evaluations depending on whether the neutral stimuli are preceded by, or paired with, un perceived emotional stimuli 142,143 . Notably, however, when subjects are aware of the presence and nature of the emotional stimuli these effects sometimes disappear 143,144 . At the neural level the subcortical system that is involved in non-conscious perception of emotional stimuli can interact with cortical areas that are associated with visual awareness and conscious perception of emotional signals.…”

Depressive signs and cognitive performance in patients with a right hemisphere stroke

“…Although the left-hemisphere has been related to higher incidence of depression, the right-hemisphere seems to be more related to emotions in general, being pointed in the literature as the main neurobiological correlate to facial emotions and prosodic processing (9) . Therefore, vascular lesions in this hemisphere may impair the patient's mental and emotional state, as well as negatively affecting motivation, comprehension and prosodic emotional, metaphoric and humor expression (10) .…”