Limbic Activation and Psychophysiologic Responses to Aversive Visual Stimuli Interaction with Cognitive Task

Abstract

Emotional responses are regulated by limbic regions of the brain, such as the amygdala, hypothalamus, limbic midbrain, and limbic cortex (anterior cingulate, orbitofrontal, temporal polar, medial temporal). The cytological organization of various limbic structures and their inter-connectivity, suggest that these regions comprise a functional network (Alheid and Heimer 1988). Extracellular recording, electrical stimulation and lesion studies implicate the amygdala and related limbic structures in the expression or modulation of emotional responses LeDoux 1986;McGaugh et al. 1996). Animal and human studies suggest that these same regions modulate autonomic components of emotional responses (Bechara et al. 1995;LaBar et al. 1995;Mangina and Beuzeron-Mangina 1996). Recent functional neuroimaging studies have demonstrated that the amygdala and cortico-limbic structures respond to fearful/aversive stimuli (Irwin et al. 1996;Reiman et al. 1997;Taylor et al. 1998;LaBar et al. 1998;Morris et al. 1999a), perception of facial expressions of fear and disgust (Breiter et al. 1996;Phillips et al. 1997;Whalen et al. 1998) (Morris et al. 1999b).Emotional responses are highly variable and influenced by diverse factors such as arousal, temperament, prior expectation, context and task demands -factors which may affect a controlled experiment. For example, the skin conductance response (SCR) to a social scene will vary depending upon the narrative context in which the scene is viewed (Geen and Rakosky 1973;Lazarus 1984). In a study examining the effects of emotional stimulus content on memory, we noted that amygdaloid activation disappeared when the task changed from rating stimuli to recognizing them, suggesting an effect of task instruction on emotional processing (Taylor et al. 1998). Although our finding was confounded by an order effect, the modulation of emotional responses by cognitive states has been demonstrated in numerous behavioral studies (Folkman and Lazarus 1985;Smith et al. 1993). They were also consistent with observations by Lane and colleagues (1997) that reported a differential pattern of limbic activation when emotional responses were evoked during different cognitive task. Reiman and colleagues (1997) findings of different regional cerebral blood flow (rCBF) patterns associated with memory-generated vs. filmgenerated sadness, also support the notion of cognitive states modulating emotional responses. In this new study, we sought to investigate a hypothesis about one cognitive factor and how it might influence limbic activation.The current [15 O]water positron emission tomography (PET) study was designed to identify components of the limbic brain (extended amygdala, thalamus, hypothalamus) associated with an emotional and psychophysiologic response to aversive pictures. As converging validation, we also simultaneously recorded peripheral autonomic measures of emotional responses (Venables and Martin 1967) and applied a voxel-by-voxel correlation analysis in order to identify regions of the brain controlling t...

μ-Opioid receptors and limbic responses to aversive emotional stimuli

“…Salient stimuli (both aversive and nonaversive), compared to a blank condition, activated the SLEA region, extending our previous findings (2), to an older cohort of male subjects, and further supporting the validity of emotional activation paradigm used. These findings are also consistent with the role of the SLEA region in processing general emotional salience, as hypothesized from our earlier work (I. Liberzon, L. R. Decker, and S. F. Taylor, unpublished work).…”

“…These large neuroanatomical regions contain central components of the limbic system, such as the amygdala and hippocampus, as well as associated limbic and paralimbic cortex (1). Functional neuroimaging studies, along with lesion data and animal research, have began to illuminate specific roles of limbic structures in various components of emotional processing, including the role of extended amygdala in salience (2,3) and the role of orbitofrontal cortex in processing reward contingencies (4). A more precise understanding of the specific roles of limbic regions is essential for a better understanding of pathological conditions involving emotional dysregulation, e.g., psychiatric disorders.…”

“…Work in our laboratory has implicated the extended amygdala in the mediation of aversive emotional responses, such as fear or disgust (2,10,11), consistent with both the animal literature (12,13) and with other imaging studies (14,15). Among the various neurotransmitter systems implicated in the regulation of limbic and paralimbic regions, the endogenous opioid system and -opioid receptors have been implicated in the modulation of fear (16), the suppression of affective defense behavior (17) and emotions (18) and in the regulation of the anxiolytic effects of benzodiazepines (19).…”

Preceding attention and the dorsomedial prefrontal cortex: Process specificity versus domain dependence

“…This is suggested by our observation that we did not observe any DMPFC activation during the preceding expectancy period. This is further supported by analogous findings in recent studies who also observed DMPFC involvement only during attention to pictures but not in the preceding period [Bermpohl et al, 2006a,b] as well as by studies on simultaneous attention [Fichtenholtz et al, 2004;Keightley et al, 2003;Lane et al, 1999;Liberzon et al, 2000;Pessoa et al, 2002;Winston et al, 2003]. This suggests that the DMPFC is specifically involved in attending stimulus perception and its associated mental states rather than being recruited by attention, i.e., expectancy, itself.…”

“…Phan et al [2002] therefore conclude that the DMPFC is engaged in implicit cognitive aspects of emotion processing that are common across emotional tasks. Recent results indicate that this implicit cognitive function may be the specific attentional modulation of emotional stimulus processing [Bermpohl et al, 2006a;Fichtenholtz et al, 2004;Keightley et al, 2003;Lane et al, 1999;Liberzon et al, 2000;Nitschke et al, 2006;Pessoa et al, 2002;Ueda et al, 2003;Winston et al, 2003]. This suggests that neural activity in the DMPFC is characterized by a specific process within a particular domain.…”