A Brief Review of Research Using Near-Infrared Spectroscopy to Measure Activation of the Prefrontal Cortex during Emotional Processing: The Importance of Experimental Design

Abstract

During the past two decades there has been a pronounced increase in the number of published research studies that have employed near-infrared spectroscopy (NIRS) to measure neural activation. The technique is now an accepted neuroimaging tool adopted by cognitive neuroscientists to investigate a number of fields, one of which is the study of emotional processing. Crucially, one brain region that is important to the processing of emotional information is the prefrontal cortex (PFC) and NIRS is ideally suited to measuring activity in this region. Compared to other methods used to record neural activation, NIRS reduces the discomfort to participants, makes data collection from larger sample sizes more achievable, and allows measurement of activation during tasks involving physical movement. However, the use of NIRS to investigate the links between emotion and cognition has revealed mixed findings. For instance, whilst some studies report increased PFC activity associated with the processing of negative information, others show increased activity in relation to positive information. Research shows differences in PFC activity between different cognitive tasks, yet findings also vary within similar tasks. This work reviews a selection of recent studies that have adopted NIRS to study PFC activity during emotional processing in both healthy individuals and patient populations. It highlights the key differences between research findings and argues that variations in experimental design could be a contributing factor to the mixed results. Guidance is provided for future work in this area in order to improve consistency within this growing field.

Prefrontal oxygenation correlates to the responses in facial skin blood flows during exposure to pleasantly charged movie

“…The previous NIRS data about the prefrontal activity during emotional interventions are quite controversial (Bendall et al. ). The variant observations may result from how to induce emotion (i.e., viewing emotionally charged pictures or facial expressions) and from a substantial difference in the subjective response to a given emotional intervention.…”

“…Unfortunately, the previous NIRS data of prefrontal activity during emotional interventions were quite controversial (Bendall et al. ). Prefrontal oxygenated hemoglobin (Oxy‐Hb) increased during viewing negatively charged pictures or fearful facial expressions (Marumo et al.…”

“…For real-time monitoring of cortical activity in a less restrained and less stressful condition, near-infrared spectroscopy (NIRS) has been developed so as to detect the dynamic changes in regional cerebral oxygenation and deoxygenation. Unfortunately, the previous NIRS data of prefrontal activity during emotional interventions were quite controversial (Bendall et al 2016). Prefrontal oxygenated hemoglobin (Oxy-Hb) increased during viewing negatively charged pictures or fearful facial expressions (Marumo et al 2009;Glotzbach et al 2011;Hosseini et al 2011;Ozawa et al 2014).…”

Cognitive Style: Time to Experiment

“…Visual search tasks can investigate the allocation of attention during task completion (i.e., Galpin and Underwood, 2005; Bendall and Thompson, 2015) and can be combined with neuroimaging techniques (Bendall and Thompson, 2016). Novel non-invasive neuroimaging techniques such as functional near-infrared spectroscopy (fNIRS) have been successfully utilized in a range of cognitive science disciplines (e.g., emotion science; Bendall et al, 2016), and offer a number of advantages including reduced cost, the ability to be employed in a wide range of tasks (e.g., during exercise; Lucas et al, 2012) and enabling data collection from groups otherwise difficult to access such as infants (Franceschini et al, 2007) and clinical populations (Matsubara et al, 2014). These benefits allow for a greater range of tasks to be investigated including those taking place outside of the laboratory.…”

Functional Near Infrared Spectroscopy: Enabling routine functional brain imaging

“…Measurements of the prefrontal cortex are particularly easy because of reduced interference from hair, but studies are and should measure from more brain regions. Recent reviews have addressed the application to emotional processing [46], mobility and aging [47], clinical psychology [48], psychiatry [7], integration with neuromodulation [49], and brain computer interfaces [50]. fNIRS complements fMRI because it permits rapid studies of larger numbers of subjects and more frequent longitudinal measurements of particular relevance for learning and treatment studies.…”