Which field of psychology studies the relationship between brain and the physical systems?

Psychophysiology

The psychophysiological response to performance-related social situations in individuals with the performance-only specifier is greater than the psychophysiological response to social situations in individuals without the performance-only specifier. Reviews of the relevant research have shown increased heart rate response and greater anxiety sensitivity in the performance-only specifier.138,139

Evidence supporting the role of noradrenaline in autonomic hyperarousal in SAD is mixed. Support for the role of this neurotransmitter in the pathophysiology of SAD comes from research demonstrating that, during anticipation of public speaking, heart rate was elevated in patients with SAD compared to controls. Furthermore, norepinephrine response to the orthostatic challenge test or to the Valsalva maneuver has also been found to be greater in people with SAD compared to controls. Using pharmacological probes, some research demonstrates increased symptomatology in patients with SAD given agents that acutely increase adrenergic activity,140 while direct infusion of epinephrine failed to cause significant elevations in anxiety.141 Further, a blunted response of growth hormone to clonidine, an alpha2-adrenergic agonist, despite normal beta-adrenergic receptor number in lymphocytes has been reported. That finding suggests reduced post-synaptic alpha2-adrenergic receptor function related to norepinephrine overactivity in SAD.142 It is also possible that the blunted growth hormone response to clonidine reflects increased activity of corticotrophin releasing factor (CRF), a critical neuropeptide in the fear response.143,144

Research utilizing serotonergic probes has found that patients with SAD display an enhanced sensitivity of specific serotonin receptor subtypes as reflected by increased anxiety and hormonal responses, despite the absence of abnormalities in platelet serotonin transporter density. Specifically, several studies have found elevated cortisol levels, but normal prolactin levels, in response to serotonergic probes in patients with SAD compared to non-anxious controls.145,146 These findings imply that post-synaptic 5-HT2 receptors may be supersensitized in SAD, while 5-HT1 receptor activity, which regulates prolactin response, may be normal. Moreover, SSRIs have demonstrated effectiveness in the treatment of SAD in numerous controlled trials.147 Nonetheless, the precise role of serotonin in the regulation of social behavior has yet to be established. Some have speculated that serotonin influences the salience of social reward through the modulation of dopaminergic transmission in mesolimbic reward pathways involving the ventral tegmental area.148 Interest in the role of dopamine in the pathophysiology of SAD has been piqued by theories that implicate the dopamine system in social reward.148 Significantly decreased cerebrospinal fluid (CSF) levels of the dopamine metabolite homovanillic acid (HVA) have been observed in SAD patients relative to controls.149 Results from neuroimaging studies have found significant reductions in striatal dopamine reuptake binding site density,150 as well as significantly decreased D2 receptor binding in the striatum151 of patients with SAD compared to non-anxious controls. Moreover, marginally significant relationships have been found between diminished D2 receptor binding and social anxiety symptom severity,151 and to trait detachment in healthy participants.152

Psychophysiology is the study of the interrelationships between mind and body. Psychophysiologists study primarily human subjects using non-invasive molar physiological responses. We describe typical psychophysiological measures such as heart rate, skin conductance, and skeletal muscle activity as used to index long-lasting states such as arousal and emotion. We also review the use of these measures to detect transient responses (such as orienting, defensive, and startle responses), and classically conditioned responses. Psychophysiology is particularly useful in the study of psychopathology because it offers nonverbal measures of psychological states and processes. We therefore review psychophysiological measures in the study of schizophrenia and psychopathy. Finally, we describe two common applications of psychophysiology in the areas of biofeedback and the detection of deception (‘lie detection’).

Psychophysiology

For 30 years, findings from psychophysiological research have played an important role in characterizing the psychobiology of PTSD and assessing key features of the disorder as specified in the DSM. The symptom “marked physiological reactions to internal or external cues that symbolize or resemble an aspect of the traumatic event(s)” (DSM-5 criterion B.5) has received considerable attention. A consistent picture has emerged demonstrating greater peripheral (e.g., electrodermal, heart rate, facial electromyogram) reactivity to stimuli that represent or are related to the traumatic events of individuals who develop PTSD.61,64,65 This heightened reactivity is stable over time66 and has been observed across individuals with PTSD resulting from a wide range of traumatic events (such as combat, sexual assault, motor vehicle accidents, cancer diagnosis, or witnessing horrific events). When assessed soon after a traumatic event, heightened physiological reactivity to trauma-related cues is predictive of subsequent severity and/or persistence of PTSD symptoms.67–70 Approximately 60%–70% of individuals who meet diagnostic criteria for PTSD show heightened psychophysiological reactivity when exposed to reminders of their particular traumatic event. The presence or absence of heightened psychophysiological reactivity to trauma-related cues could reflect different subtypes of PTSD, e.g., fear-based vs. distress-based PTSD.66 Few individuals who do not meet diagnostic criteria for PTSD show this heightened reactivity.71 Psychophysiological reactivity to trauma-related cues has also been found useful as a measure of treatment outcome.72,73 The fact that some individuals can meet diagnostic criteria for PTSD, yet show little or no psychophysiological reactivity when confronted with trauma-related cues, raises interesting questions regarding whether it is reasonable to assume that self-reported experiences provide an adequate basis on which to establish the PTSD diagnosis.

Another PTSD symptom that has been the focus of considerable psychophysiological investigation is exaggerated startle (DSM-5 criterion E.4). Exaggerated startle has long been recognized as a central feature of post-trauma reactions and may be one of the most reliably reported symptoms of the disorder. However, research support for exaggerated startle, which typically is measured from the eye-blink response to a brief, sudden, loud acoustic stimulus, has been somewhat unreliable.65,74 Context is an important moderator of the startle response and may help to explain the equivocal findings. Specifically, individuals with PTSD have been found to more reliably show increased startle in the presence of contextual anxiety cues (e.g., anticipation of a threatened shock or needle stick).74 This suggests that PTSD is associated with a heightened sensitivity to threatening cues or contexts. Findings from prospective studies75–77 and a study of monozygotic twins discordant for trauma exposure and PTSD71 suggest that exaggerated eye-blink startle is not a pre-existing marker of risk for PTSD.

I.E Computers

Most psychophysiology laboratories now employ small computers for on-line control of experiments and immediate analysis of data and also for more complex subsequent analyses. Laboratory interface systems are available that make it possible to turn things on and off under computer control, to generate stimuli, to time events, and also to provide to the computer data, command signals, and other information from the laboratory. The computer can present pictorial or alphanumeric information to the subject by means of a monitor display and also a variety of auditory stimuli including spoken words such as “right,” “wrong,” and “good,” which have been digitally recorded and stored in the computer's memory. Psychophysiologists of the past have required a working knowledge of electrical principles, physiology, and statistics and a more than rudimentary understanding of psychology; competent psychophysiologists of the present require a working knowledge of the computer as well.

Conclusion

Great advances have been made since the Royal Commission on Animal Magnetism concluded in 1784 that Mesmer’s procedure produced authentic clinical effects that were probably explained by the patient’s imagination. Recent research demonstrates that hypnotic states are characterized by mental relaxation, absorption, reduction in orientation toward time and sense of self, and automaticity. Changes along each of these experiential dimensions reflect changes in activity within partly separate brain networks. This complexity renders the discovery of a unique physiological marker of hypnotic states highly unlikely. However, it does provide a formal structure to establish whether a hypnotic state is occurring and to determine the similarities with and differences from other altered states of consciousness.

Hypnotic changes in the acute pain experience are further associated with a reduction in the activation observed within the cortical territories that receive nociceptive signals from the spino–thalamo–cortical pathways. These changes can consist of selective alterations in the affective dimension of pain or reductions in both the sensory and affective dimensions, depending on the nature of the suggestions. Selective changes in only the affective components of pain are associated with corresponding changes in ACC activity, and changes in sensory components are accompanied by corresponding changes in somatosensory cortical activity. Reinterpretations of the meaning of pain, dissociation, and focused analgesia reflect different psychological mechanisms of hypnotic analgesia that may engage different brain processes. These multiple mechanisms are likely to be associated with intracortical and descending cerebral–spinal cord mechanisms to varying extents. Although some evidence indicates that hypnotic analgesia has demonstrable clinical efficacy, there is still a strong need for improvements in the methodology of clinical studies. In particular, there is a need to compare the efficacy of different hypnotic approaches and provide rigorous standardized outcome measures.

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Abstract

Psychophysiology is the study of the relationship between physiological signals recorded from the body and brain to mental processes and disorders. These biological signals may be generated by activity of organs in the body or by muscle activity. In addition, a wide variety of methods can detect neural activity generated within the brain. Brain recordings or imaging include measurement of electrical signals generated by neurons, changes in cerebral blood flow or alterations in brain metabolism. This article provides an overview of psychophysiological methods and how these can be used to understand healthy and disturbed psychological function, to assess mental or neurological illness, to investigate neurobiological mechanisms associated with mental disorders and to develop therapies for human illnesses.

Integrating Psychophysiology and Neuroscience

Psychophysiology is concerned with understanding the interrelations between the mind, body, and behavior. It has been suggested that because psychophysiology is positioned at the crossroads of multiple disciplines (e.g. cognitive science, affective neuroscience and physiology), it may constitute a “vital cog” in the measurement of brain-behavior relationships, especially at the intersection of cognition and emotion. This is particularly relevant to addictive behaviors, which are emotionally reinforced, and to addiction treatments that aim to increase cognitive control of alcohol and drug use behaviors. Within this context, it is paradoxical that with few exceptions, psychophysiological methods historically did not play a pivotal role in understanding regulatory systems that contribute to behavioral flexibility in general, or loss of behavioral flexibility toward alcohol and drugs in particular. This is believed to be due in part to the early unidirectional, stimulus–response approach to psychophysiology wherein bodily reactions were conceptualized simply as responses to a neural command. These approaches neglected the recursive nature of body–brain communication and the critical role that a bodily reaction plays in neural dynamics. Without a complete circuit of information exchange, however, the brain would be unable to determine how well its commands had been carried out or whether its suggested response had succeeded in adapting to a perturbation.

Fortunately, there has been a recent paradigm shift away from overly simplified psychophysiological approaches and, along with the reawakened neuroscientific interest in oscillatory variability in the brain, knowledge about the specific ways in which bodily processes are embedded within the neurophysiological systems has dramatically expanded. Accordingly, psychophysiology is emerging as a long-lost relative to the field of neuroscience. The merging of these disciplines is moving toward the development of “neuropsychophysiological” systems theories to provide a lawful approach to the study and understanding of bodily functions, such as heart rate and blood pressure, in relation to the neural systems that control, and are affected by them. Systems approaches are now being used to examine addiction and other mental health disorders to inform and constrain interpretation of autonomic nervous system (ANS) activity, and to study how changes in the body participate together with changes in the brain to determine not only physical health, but behavioral flexibility and control.

Here we use a systems framework to describe ANS participation in arousal modulation as a component process in the development and maintenance of addictive behaviors. This framework is heuristic because it provides a new way to frame addiction research questions that moves beyond static conceptions of individual differences. In particular, HRV is studied in terms of both a basal state and as a phasic reactive and modulatory process that expresses in real time response to internal and environmental challenges. Thus, HRV captures a physiological regulatory function as it unfolds on a moment-to-moment basis, and its assessment is particularly well-suited to integrate in real time with brain imaging modalities such as electroencephalography (EEG), functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and positron emission tomography (PET) (see Human Neurophysiology: EEG and Quantitative EEG in Addiction Research, Multinuclear Magnetic Resonance Methods and the Study of Mechanisms of Addiction in Humans, Alcohol Neuroimaging in Humans, Neuroimaging of Nicotine and Tobacco Smoking in Humans, Ecstasy (MDMA) and other designer drugs: Neuroimaging, Genetics of Alcohol Use Disorders, Cocaine and Amphetamine Neuroimaging in Small Rodents, The Impact of Regular Cannabis Use on the Human Brain: A Review of Structural Neuroimaging Studies), as well as the more precise, yet invasive assessments of neural processes that are used in animal models of addiction (see Mice and Alcohol, Alcohol and Rats, Nonhuman Primate Models of Alcohol Abuse and Alcoholism, Zebrafish and Alcohol, Alcohol and Drosophila melanogaster, Animal Models of Addiction other than Alcohol: Amphetamines, Animal Models of Addiction: Cannabinoids, Animal Models of Drug Addiction: Cocaine, Effects of Nicotine in Animal Models of Drug Addiction Across Species, Preclinical Animal Studies: Alcohol, Preclinical Animal Studies: Cannabinoids, Preclinical Animal Studies: Cocaine, Preclinical Animal Studies: Nicotine, Preclinical Animal Studies: Opiates, Overview of Animal Models of Drug Addiction: Commonalities to Human Addiction).

Autonomic expression of cognitive conflict and error detection

Psychophysiology highlights the link between changes in bodily arousal state and the behavioral significance of stimuli and actions. In the case of threat, a change in bodily arousal is part of a protective response, i.e., an evolutionarily selected, survival-related response repertoire where the evoked shift in bodily state facilitates an adaptive behavior, e.g., escape motor action. The same type of shifts in body state also occur during types of “cold” cognitive processing, for example, when behavioral strategies need to be changed. One view, promoted especially by Damasio and colleagues, is that fluctuations in bodily arousal contribute to cognitive processes themselves, and feed back to influence and bias thoughts, judgments, and behaviors (Damasio et al., 1991a). This may be particularly useful in correcting suboptimal behaviors.

Certain cognitive tasks, such as the Stroop interference task, evoke demands on attentional processes through cognitive conflicts that are measurable behaviorally from response times, autonomic reactions, and behavioral error. In the “standard” color-word Stroop task, a participant reads from a list of words written in different ink colors. The words are all names of colors. The participant then goes through the list again, naming the ink color of the words while ignoring what is actually written. It is harder (i.e., participants are slower and/or make more errors) to name the ink color (e.g., red) of a word for a different color (e.g., blue). Such cognitive conflict (interference) is generated where a response is required that goes against a prepotent or “more natural” response to the stimuli. Stroop task performance is particularly associated with the engagement of dorsal anterior cingulate cortex. One influential formulation attributes cingulate activation to more than attentional demand, suggesting its central role in rapid detection and signaling of cognitive conflict and behavioral error (e.g., Bechtereva et al., 1990; Dehaene et al., 1994; Bush et al., 2000). An imaging study set out to unpick how the role of dorsal anterior cingulate in effort-related autonomic control might relate to cognitive conflict and error detection: The study measured task-evoked changes in brain activity and autonomic response (here sympathetic influences on pupil size) during performance of a “numerical” Stroop task. It was observed that errors in Stroop task performance elicited greatest effects on pupil diameter, always on trials where there was a conflict (Critchley et al., 2005c). Activity within regions of dorsal anterior cingulate and dorsomedial frontal cortex reflected fluctuations in pupil size and the presence of cognitive conflict in the stimuli. One area in particular was engaged when errors were made that evoked specific high-magnitude pupillary arousal responses. Findings from other studies suggest that this type of autonomic response to error occurs when there is conscious awareness of having made the error (Nieuwenhuis et al., 2001; Hajcak et al., 2003). The imaging study therefore provided insight into a brain area (within dorsal anterior cingulate) integrating adaptive changes in bodily state with conscious self-monitoring. This physiological signal of a cognitive process may represent what Damasio might term a “somatic marker,” shifting the physiological context and feeding back to bias cognitive behavior to avoid further mistakes over ensuing trials (see Fig. 6.2).

Conclusion

The psychophysiology of disease is a vigorous and exciting area of research. It involves the integration of several disciplines including neuroscience, pathophysiology, and health psychology, and in each of these areas new discoveries are constantly changing our levels of understanding. The complexity of links between the brain, peripheral physiological function, and disease risk is formidable, and linear models are of limited value. The broad processes linking psychophysiological factors with disease risk are now understood, although many of the biological mediators remain tantalizingly elusive. Important challenges for future research include delineation of the processes through which psychosocial factors such as social inequality and social isolation affect disease, understanding how emotional and behavioral coping responses can modify physiological reaction patterns and contribute to resistance and vulnerability, and defining the ways in which psychophysiological knowledge can be harnessed for prevention and disease management. Techniques such as brain imaging, genetic analysis, molecular biological approaches to gene expression, and assays of the microbiome will become more prominent in the field. We are also likely to see greater integration of behavioral medicine work on physical diseases with studies of behavioral and psychiatric problems. Psychophysiology is one of the cornerstones of clinical health psychology and is of prime importance in understanding how psychological and social experience can influence health and disease.

8.02.8 Conclusion

The psychophysiology of disease is a vigorous and exciting area of research. It involves the integration of several disciplines including neuroscience, pathophysiology, and health psychology, and in each of these areas new discoveries are constantly changing our levels of understanding. The complexity of links between the brain, peripheral physiological function, and disease risk is formidable, and linear models are of limited value. The broad processes linking psychophysiological factors with disease risk are now understood, although many of the biological mediators remain tantalizingly elusive. Important challenges for future research include delineation of the processes through which psychosocial factors such as social inequality and social isolation affect disease, understanding how emotional and behavioral coping responses can modify physiological reaction patterns and contribute to resistance and vulnerability, and defining the ways in which psychophysiological knowledge can be harnessed for prevention and disease management. Techniques such as brain imaging, genetic analysis, molecular biological approaches to gene expression, and assays of the microbiome are becoming more prominent in the field. We are also likely to see greater integration of behavioral medicine work on physical diseases with studies of behavioral and psychiatric problems. Psychophysiology is one of the corner-stones of clinical health psychology, and is of prime importance in understanding how psychological and social experience can influence health and disease.