Anxiety and defensiveness: individual differences in affective startle modulation

Induced Positive Affect Reduces the Magnitude of the Startle Response and Prepulse Inhibition

Abstract. The startle response is a reflex that represents a form of adaptation to environmental changes potentially relevant to survival. Startle magnitude can change depending on a number of factors such as the affective state of the organism during the presentation of the startle-inducing stimulus, or the so-called Prepulse Inhibition (PPI) that occurs when the startling stimulus (or Pulse) is preceded by a low-intensity stimulus (or Prepulse). This paper describes an experiment designed to analyze the impact of an induced positive affect on the magnitude of the startle response and PPI in adult humans. Specifically, each participant received alternating exposures to a picture of a face of a loved person (positive affect condition) or to a picture of a face of an unknown person (control condition) while the startle response and PPI were recorded. The results showed a decrease in both the magnitude of the startle response and percent PPI on the positive affect trials when compared with the control trials. These results are interpreted from psychophysiological and psychological perspectives considering the role of emotions in adaptive behavior.

A Motivational Framework for Psychopathy: Toward a Reconceptualization of the Disorder

Abstract. The link between psychopathy and violence has been well documented. Estimates suggest psychopathic offenders are responsible for as much as 40% of violence-related crime, and that they show rates of violent recidivism up to five times higher than non-psychopathic offenders. Existing theories of the disorder argue that this violence stems from a core insensitivity to emotional/aversive information, or from a core inability to optimally allocate processing resources in complex environments. However, some newer findings have been difficult for existing theories to assimilate; moreover, successful treatment programs based off current conceptualizations have been slow to develop. With this in mind, the current paper proposes a new motivational framework for psychopathy, within which the disorder is conceptualized as stemming from more strategic, motivated processes. The paper begins by reviewing traditional theories of psychopathy and highlighting their explanatory strengths and limitations. The proposed motivational framework is then outlined, and a supportive rationale for the framework provided. Next, the paper undertakes a selective review of some of the most empirically supported features of the disorder, to highlight how these features may be productively reformulated within a motivational framework. Finally, the paper suggests several methods through which an empirical evaluation of the proposed ideas may be undertaken, and explores potential implications of a motivational framework for next-generation rehabilitation and treatment opportunities.

Affective startle modulation and psychopathology: Implications for appetitive and defensive brain systems

Startle reflex potentiation versus startle attenuation to unpleasant versus pleasant stimuli likely reflect priming of the defensive versus appetitive motivational systems, respectively. This review summarizes and systemizes the literature on affective startle modulation related to psychopathologies with the aim to reveal underlying mechanisms across psychopathologies. We found evidence for psychopathologies characterized by increased startle potentiation to unpleasant stimuli (anxiety disorders), decreased startle potentiation to unpleasant stimuli (psychopathy), decreased startle attenuation to pleasant stimuli (ADHD), as well as a general hyporeactivity to affective stimuli (depression). Increased versus decreased startle responses to disorder-specific stimuli characterize specific phobia and drug dependence. No psychopathology is characterized by increased startle attenuation to standard pleasant stimuli or a general hyperreactivity to affective stimuli. This review indicates that the defensive and the appetitive systems operate independently mostly in accordance with the motivational priming hypothesis and that affective startle modulation is a highly valuable paradigm to unraveling dysfunctions of the defensive and appetitive systems in psychopathologies as requested by the Research Domain Criteria initiative.

Capacity for upregulation of emotional processing in psychopathy: all you have to do is ask

Historically, psychopathic individuals have been described as suffering a chronic hyporesponsivity to negatively valent stimuli. However, while a wide body of empirical work indicates that the psychopath does not manifest normal reactivity to emotional stimuli, it does not similarly indicate that they cannot do so. To attempt to differentiate these alternatives, the current functional magnetic resonance imaging (fMRI) study evaluated the extent to which offenders with varying PCL-R scores could up- (or down-) regulate their neural response to negatively valent stimuli. Participants were asked to either watch negatively- and neutrally-valent images naturally (passive-processing), or to try to increase or decrease their emotional response to the images (instructed-processing). During passive processing, high-psychopathy offenders showed reduced activity compared to both low- and mid-psychopathic offenders through a majority of emotion-relevant regions. However, when participants were instructed to try to increase their emotional response all groups showing increased activity throughout relevant regions, including left insula, orbitofrontal cortex and anterior cingulate/medial frontal cortex (ACC/mFC). Comparison of participants' subjective emotion ratings indicated that all groups showed symmetry between their neural/subjective emotion metrics, and the high-psychopathy group may have showed the greatest such symmetry. These findings suggest that psychopathic individuals may be capable of manifesting emotional reactivity to negatively valent stimuli, at least under certain conditions. Relevance for traditional and developing models of psychopathy is discussed in turn.

Modulation of the startle reflex by heat pain: does threat play a role?

BACKGROUND

Previous studies have indicated that the startle reflex is potentiated by phasic, but not by tonic, heat pain, although the latter is seen as more strongly associated with emotional responses and more similar to clinical pain. The threat value of pain might be a decisive variable, which is not influenced alone by stimulus duration.

OBJECTIVE

This study aimed at comparing startle responses to tonic heat pain stimulation with varying degrees of threat. We hypothesized that the expectation of unpredictable temperature increases would evoke higher threat and thereby potentiate startle compared with the expectation of constant stimulation.

METHODS

Healthy, pain-free subjects (n = 40) underwent painful stimulation in two conditions (low/high threat) in balanced order. The only difference between the two conditions was that in the high-threat condition 50% of the trials were announced to include a short further noxious temperature increase at the end. Startle tones were presented prior to this temperature increase still in the phase of anticipation.

RESULTS

We observed startle potentiation in the high-threat compared with the low-threat condition, but only in those participants who took part first in the high-threat condition. Habituation could not account for these findings, as we detected no significant decline of startle responses in the course of both conditions.

CONCLUSIONS

Our results suggest that subjective threat might indeed be decisive for the action of pain on startle; the threat level appears not only influenced by actual expectations but also by previous experiences with pain as threatening or not.

The startle response: developmental effects and a paradigm for children and adults

A film paradigm was developed to examine baseline and emotion modulated startle across a broad age range from preschool to adulthood. The paradigm was tested in children (3-, 5-, 7-, and 9-year-olds) and adults (total N = 122). The paradigm elicited a similar startle potentiation pattern across age groups; however, baseline startle changed with age: 3- and 5-year-olds showed lower response probability and magnitude of baseline startle than adults. Females exhibited larger baseline startle response probability and overall magnitude than did males; however, no sex by emotion modulated startle interaction was noted. Anxiety measures were obtained for all children. Individual differences in anxiety were associated with baseline startle magnitude among older but not younger children. No association of anxiety with startle potentiation was noted. Overall the film paradigm was applicable across a wide developmental span, revealing potential developmental and gender differences in baseline startle magnitude and response probability.