Increase In Prefrontal Cortex Activity Research Articles

Prefrontal cortex activation under stress as a function of borderline personality disorder in female adolescents engaging in non-suicidal self-injury.

Neuroimaging studies suggest alterations in prefrontal cortex (PFC) activity in healthy adults under stress. Adolescents with non-suicidal self-injury (NSSI) report difficulties in stress and emotion regulation, which may be dependent on their level of borderline personality disorder (BPD). The aim was to examine alterations in the PFC in adolescents with NSSI during stress. Adolescents (13-17 years) engaging in non-suicidal self-injury (n = 30) and matched healthy controls (n = 29) performed a task with low cognitive demand and the Trier Social Stress Test (TSST). Mean PFC oxygenation across the PFC was measured with an eight-channel near-infrared spectroscopy system. Alongside self-reports on affect, dissociation and stress, BPD pathology was assessed via clinical interviews. Mixed linear-effect models revealed a significant effect of time on PFC oxygenation and a significant time×group interaction, indicating increased PFC activity in patients engaging in NSSI at the beginning of the TSST compared with healthy controls. Greater BPD symptoms overall were associated with an increase in PFC oxygenation during stress. In exploratory analyses, mixed models addressing changes in PFC connectivity over time as a function of BPD symptoms were significant only for the left PFC. Results indicate differences in the neural stress response in adolescents with NSSI in line with classic neuroimaging findings in adults with BPD. The link between PFC oxygenation and measures of BPD symptoms emphasises the need to further investigate adolescent risk-taking and self-harm across the spectrum of BPD, and maybe overall personality pathology, and could aid in the development of tailored therapeutic interventions.

The Time Course of Changes in Prefrontal Cortex Activity During Walking in People With Parkinson's Disease.

Walking abnormalities in people with Parkinson's disease (PD) are characterized by a shift in locomotor control from healthy automaticity to compensatory, executive control, mainly located in the prefrontal cortex (PFC). Although PFC activity during walking increases in people with PD, the time course of PFC activity during walking and its relationship to clinical or gait characteristics is unknown. To identify the time course of PFC activity during walking in people with PD. To investigate whether clinical or gait variables would explain the PFC activity changes. Thirty-eight people with PD tested OFF medication wore a portable, functional near-infrared spectroscopy (fNIRS) system to record relative PFC activity while walking. Wearable inertial sensors recorded spatiotemporal gait characteristics. Based on the PFC activity (fNIRS) in the late phase of the walking task (final 40 seconds), compared to the early phase (initial 40 seconds), participants were separated into 2 groups: reduced or sustained PFC activity. People with PD who reduced PFC activity during walking had less impaired gait (eg, faster gait speed) than those who had a sustained increase in PFC activity (P < .05). Cognitive set-shifting ability explained 18% of the PFC activation in the group with a sustained increase in PFC activity (P = .033). The time course of reduction in PFC activity corresponds to less impaired gait performance in people with PD, while a sustained increase in PFC activity is related to worse cognitive flexibility. Reduction in PFC activity while walking may indicate a less impaired, automatic control of walking.

Unraveling emotional regulation through multimodal neuroimaging techniques

Neuroimaging techniques have significantly advanced our understanding of emotional regulation by elucidating the neural mechanisms involved. This review synthesizes findings across multiple modalities—functional Magnetic Resonance Imaging (fMRI), Electroencephalography (EEG), Magnetoencephalography (MEG), Positron Emission Tomography (PET), and Magnetic Resonance Spectroscopy (MRS)—to highlight key insights into emotional processing. The prefrontal cortex (PFC), amygdala, hippocampus, and insula emerge as critical brain regions in regulating emotions. fMRI studies demonstrate increased PFC activity and decreased amygdala responses during effective emotion regulation, indicating top-down control mechanisms. EEG and MEG provide insights into the temporal dynamics of emotional responses, capturing rapid changes in neural activity during emotional tasks. PET and MRS studies reveal the neurochemical basis of emotional regulation, emphasizing the roles of neurotransmitters like serotonin and dopamine. Integration of multimodal approaches, such as fMRI-EEG and fMRI-PET, enhances our understanding by combining spatial, temporal, and neurochemical specificity. Challenges include methodological limitations and the need for diverse participant samples to improve generalizability. Future research should focus on improving spatial and temporal resolution, adopting longitudinal and ecologically valid designs, and fostering interdisciplinary collaborations. These advancements hold promise for developing personalized interventions and treatments for emotional disorders by leveraging neuroimaging biomarkers and understanding the neural underpinnings of emotional regulation.

Prefrontal activity and heart rate variability during cognitive tasks may show different changes in young and older adults with and without mild cognitive impairment.

Age-related decline in cognitive function is often linked to changed prefrontal cortex (PFC) activity and heart rate variability (HRV). Mild cognitive impairment (MCI), a transitional stage between normal aging and dementia, might have further degeneration beyond aging. This study aimed to investigate the differences between young and older adults with or without MCI in cognitive functions, task-induced PFC activation and HRV changes. Thirty-one healthy young adults (YA), 44 older adults (OA), and 28 older adults with MCI (OA-MCI) were enrolled and compared in this cross-sectional study. Each participant received a one-time assessment including cognitive and executive functions, as well as the simultaneous recording of PFC activity and HRV during a cognitive task paradigm. We observed age-related decrease in global cognitive functions, executive functions, HRV, and increase in PFC activity. The MCI further deteriorated the global cognitive and executive performances, but not the HRV or the prefrontal activation. Older people showed lower performances in general cognitive function and executive function, compensatory increase of PFC activity, and reduced HRV. Older people with MCI had further deterioration in cognitive performance, but not in PFC activation and HRV.

Prefrontal Cortex Activity During Gait in People With Persistent Symptoms After Concussion

Background Concussions result in transient symptoms stemming from a cortical metabolic energy crisis. Though this metabolic energy crisis typically resolves in a month, symptoms can persist for years. The symptomatic period is associated with gait dysfunction, the cortical underpinnings of which are poorly understood. Quantifying prefrontal cortex (PFC) activity during gait may provide insight into post-concussion gait dysfunction. The purpose of this study was to explore the effects of persisting concussion symptoms on PFC activity during gait. We hypothesized that adults with persisting concussion symptoms would have greater PFC activity during gait than controls. Within the concussed group, we hypothesized that worse symptoms would relate to increased PFC activity during gait, and that increased PFC activity would relate to worse gait characteristics. Methods The Neurobehavior Symptom Inventory (NSI) characterized concussion symptoms. Functional near-infrared spectroscopy quantified PFC activity (relative concentration changes of oxygenated hemoglobin [HbO2]) in 14 people with a concussion and 25 controls. Gait was assessed using six inertial sensors in the concussion group. Results Average NSI total score was 26.4 (13.2). HbO2 was significantly higher (P = .007) for the concussed group (0.058 [0.108]) compared to the control group (−0.016 [0.057]). Within the concussion group, HbO2 correlated with NSI total symptom score (ρ = .62; P = .02), sagittal range of motion (r = .79; P = .001), and stride time variability (r = −.54; P = .046). Conclusion These data suggest PFC activity relates to symptom severity and some gait characteristics in people with persistent concussion symptoms. Identifying the neurophysiological underpinnings to gait deficits post-concussion expands our knowledge of motor behavior deficits in people with persistent concussion symptoms.

Psi Chi/APA Edwin B. Newman Graduate Research Award: Daliah Ross.

Presents Daliah Ross as the 2022 winner of the American Psychological Association Psi Chi/APA Edwin B. Newman Graduate Research Award. This award is given for an exceptional research article titled, 'Prefrontal Cortex Activation During Dual-Task Walking in Older Adults Is Moderated by Thickness of Several Cortical Regions.' This work was based on the concept of neural inefficiency (i.e., greater neural activation coupled with similar or worse performance) and hypothesized that decreased cortical thickness across multiple brain regions would be associated with greater increases in prefrontal cortex activation from single- to dual-task walking. Ms. Ross's research appears to be the first study to examine cortical thickness as a marker of neural inefficiency during active walking. The cortical regions implicated, involved in sensory, motor, and cognitive functioning, provided further evidence for the complicated nature of cognitive control of locomotion in aging. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Effects of different exercise intensities on prefrontal activity during a dual task

The effects of physical exercise on cognitive tasks have been investigated. However, it is unclear how different exercise intensities affect the neural activity. In this study, we investigated the neural activity in the prefrontal cortex (PFC) by varying the exercise intensity while participants performed a dual task (DT). Twenty healthy young adults performed serial subtraction while driving a cycle ergometer. Exercise intensity was set to one of three levels: low, moderate, or high intensity. We did not find any significant change in PFC activity during DT under either the control (no exercise) or low-intensity conditions. In contrast, we observed a significant increase in PFC activity during DT under moderate- and high-intensity conditions. In addition, we observed complex hemodynamics after DT. PFC activity decreased from baseline after DT under the control condition, while it increased under the low-intensity condition. PFC activity remained higher than the baseline level after DT under the moderate-intensity condition but returned to baseline under the high-intensity condition. The results suggest that moderate-intensity exercise with a cognitive load effectively increases PFC activity, and low-intensity exercise may increase PFC activity when combined with a cognitive load.

Similarities and differences in the induction and regulation of the negative emotions fear and disgust: A functional near infrared spectroscopy study.

Affective processing, including induction and regulation of emotion, activates neural networks, induces physiological responses, and generates subjective experience. Dysregulation of these processes can lead to maladaptive behavior and even psychiatric morbidity. Multimodal studies of emotion thus not only help elucidate the nature of emotion, but also contribute to important clinical insights. In the present study, we compared the induction (EI) and effortful regulation (ER) with reappraisal of fear and disgust in healthy subjects using functional near infrared spectroscopy (fNIRS) in conjunction with electrodermal activity (EDA). During EI, there was significant activation in medial prefrontal cortex (PFC) for fear and more widespread activation for disgust, with right lateral PFC significantly more active during disgust compared to fear. ER was equally effective for fear and disgust reducing subjective emotion rating by roughly 45%. Compared to baseline, there was no increased PFC activity for fear during ER, while for disgust lateral PFC was significantly more active. Significant differences between the two negative emotions were also observed in sympathetic nerve activity as reflected in EDA during EI, but not during ER. Lastly, compared to men, women had higher emotion rating for both fear and disgust without corresponding differences in EDA. In conclusion, in the present study we show that emotion induction was associated with differential activation in both PFC and sympathetic nerve activity for fear and disgust. These differences were however less prominent during emotion regulation. We discuss the potential interpretation of our results and their implications regarding our understanding of negative emotion processing.

An active inference model of conscious access: How cognitive action selection reconciles the results of report and no-report paradigms.

Cognitive theories of consciousness, such as global workspace theory and higher-order theories, posit that frontoparietal circuits play a crucial role in conscious access. However, recent studies using no-report paradigms have posed a challenge to cognitive theories by demonstrating conscious accessibility in the apparent absence of prefrontal cortex (PFC) activation. To address this challenge, this paper presents a computational model of conscious access, based upon active inference, that treats working memory gating as a cognitive action. We simulate a visual masking task and show that late P3b-like event-related potentials (ERPs), and increased PFC activity, are induced by the working memory demands of self-report generation. When reporting demands are removed, these late ERPs vanish and PFC activity is reduced. These results therefore reproduce, and potentially explain, results from no-report paradigms. However, even without reporting demands, our model shows that simulated PFC activity on visible stimulus trials still crosses the threshold for reportability – maintaining the link between PFC and conscious access. Therefore, our simulations show that evidence provided by no-report paradigms does not necessarily contradict cognitive theories of consciousness.

Aerobic Exercise Combined With Transcranial Direct Current Stimulation Over the Prefrontal Cortex in Parkinson Disease: Effects on Cortical Activity, Gait, and Cognition

Background Since people with Parkinson disease (PD) rely on limited prefrontal executive resources for the control of gait, interventions targeting the prefrontal cortex (PFC) may help in managing PD-related gait impairments. Transcranial direct current stimulation (tDCS) can be used to modulate PFC excitability and improve prefrontal cognitive functions and gait. Objective We investigated the effects of adding anodal tDCS applied over the PFC to a session of aerobic exercise on gait, cognition, and PFC activity while walking in people with PD. Methods A total of 20 people with PD participated in this randomized, double-blinded, sham-controlled crossover study. Participants attended two 30-minute sessions of aerobic exercise (cycling at moderate intensity) combined with different tDCS conditions (active- or sham-tDCS), 1 week apart. The order of sessions was counterbalanced across the sample. Anodal tDCS (2 mA for 20 minutes [active-tDCS] or 10 s [sham-tDCS]) targeted the PFC in the most affected hemisphere. Spatiotemporal gait parameters, cognitive functions, and PFC activity while walking were assessed before and immediately after each session. Results Compared with the pre-assessment, participants decreased step time variability (effect size: −0.4), shortened simple and choice reaction times (effect sizes: −0.73 and −0.57, respectively), and increased PFC activity in the stimulated hemisphere while walking (effect size: 0.54) only after aerobic exercise + active-tDCS. Conclusion The addition of anodal tDCS over the PFC to a session of aerobic exercise led to immediate positive effects on gait variability, processing speed, and executive control of walking in people with PD.

Functional Near-infrared Spectroscopy Reveals the Compensatory Potential of Pre-frontal Cortical Activity for Standing Balance in Young and Older Adults

Recent evidence suggests increased activity of the pre-frontal cortex (PFC) is associated with sensorimotor disturbances of standing balance. Here we manipulate sensorimotor inputs and concurrently load cognitive resources in order to investigate the functional role of PFC activity during standing balance, and how this changes with healthy ageing. Healthy younger (n = 24; mean age = 20.8 years) and older (n = 25; mean age = 70.6 years) adults maintained balance while sensorimotor inputs were manipulated by removing vision, reducing the base of support, and reducing proprioceptive feedback. To load cognitive resources, each balance condition was undertaken alone or simultaneously with a cognitive task (dual-task). Functional near infrared spectroscopy (fNIRS) measured PFC activity and a force-plate measured postural sway. When comparing dual-tasks relative to single balance tasks (dual-task effect), at lower levels of balance task demand, the older adults exhibited increased PFC activity and similar levels of postural sway. However, at higher levels of balance task demand, a limit to PFC activity was observed and postural sway became more unstable in older adults. In contrast, for younger adults at higher levels of balance task demand, the dual-task effect resulted in an increase in PFC activity and postural sway was not unduly affected. These results suggest that PFC activity is compensating for sensorimotor deficits to maintain stability, and that a cognitive resource limit is reached for easier balance tasks in older people compared to younger people. These results suggest that increasing cortical capacity in older people may improve their balance.

Neurophysiological biomarkers of response inhibition and the familial risk for borderline personality disorder

Understanding of the biological factors that run in families affected with borderline personality disorder (BPD) is limited. The authors investigated the familial aggregation of neurophysiological biomarkers of response inhibition in the first-degree biological relatives of probands with BPD and associations with psychiatric diagnosis and impulsive traits. In the present study, psychiatric diagnoses and impulsive traits were measured in BPD probands (n = 86), psychiatrically affected and non-affected relatives (n = 60) and controls (n = 83). While undergoing neuroimaging using functional near-infrared spectroscopy, prefrontal cortex (PFC) activation was measured during a go/no-go response inhibition task and compared between probands, relatives and controls. Additionally, non-psychiatrically affected relatives and controls were contrasted to examine the potential impact of familial risk for BPD on response inhibition-related PFC activation in the absence of confounding psychiatric morbidity. Probands showed bilateral decreases in PFC activation during response inhibition compared to relatives and controls. Conversely, both affected and non-affected relatives displayed higher activation than controls and probands in left lateral/medial and right medial PFC, although non-affected relatives showed a lesser extent of activation than affected relatives. Probands and controls reporting greater impulsive traits displayed deactivation across the PFC during response inhibition, whereas relatives showed increased activation. In this first family study of neuroimaging biomarkers in BPD, we show that the familial risk for BPD is reflected in activation of the PFC during response inhibition, with lifetime psychiatric diagnosis and higher impulsive traits in relatives associated with larger increases in PFC activity. Higher PFC activity during response inhibition including among non-affected relatives could reflect a neurophysiological compensatory mechanism.

Prefrontal Cortex Activity During Walking: Effects of Aging and Associations With Gait and Executive Function

Background Declines in gait parameters are common with aging and more pronounced in tasks with increased executive demand. However, the neural correlates of age-related gait impairments are not fully understood yet. Objectives To investigate (a) the effects of aging on prefrontal cortex (PFC) activity and gait parameters during usual walking, obstacle crossing and dual-task walking and (b) the association between PFC activity and measures of gait and executive function. Methods Eighty-eight healthy individuals were distributed into 6 age-groups: 20-25 (G20), 30-35 (G30), 40-45 (G40), 50-55 (G50), 60-65 (G60), and 70-75 years (G70). Participants walked overground under 3 conditions: usual walking, obstacle crossing, and dual-task walking. Changes in oxygenated and deoxygenated hemoglobin in the PFC were recorded using functional near-infrared spectroscopy. Gait spatiotemporal parameters were assessed using an electronic walkway. Executive function was assessed through validated tests. Results Between-group differences on PFC activity were observed for all conditions. Multiple groups (ie, G30, G50, G60, and G70) showed increased PFC activity in at least one of the walking conditions. Young adults (G20 and G30) had the lowest levels of PFC activity while G60 had the highest levels. Only G70 showed reduced executive function and gait impairments (which were more pronounced during obstacle crossing and dual-task walking). PFC activity was related to gait and executive function. Conclusions Aging causes a gradual increase in PFC activity during walking. This compensatory mechanism may reach the resource ceiling in the 70s, when reduced executive function limits its efficiency and gait impairments are observed.

Age-Related Compensatory Reconfiguration of PFC Connections during Episodic Memory Retrieval.

During demanding cognitive tasks, older adults (OAs) frequently show greater prefrontal cortex (PFC) activity than younger adults (YAs). This age-related increase in PFC activity is often associated with enhanced cognitive performance, suggesting functional compensation. However, the brain is a complex network of interconnected regions, and it is unclear how network connectivity of PFC regions differs for OAs versus YAs. To investigate this, we examined the age-related difference on the functional brain networks mediating episodic memory retrieval. YAs and OAs participants encoded and recalled visual scenes, and age-related differences in network topology during memory retrieval were investigated as a function of memory performance. We measured both changes in functional integration and reconfiguration in connectivity patterns. The study yielded three main findings. First, PFC regions were more functionally integrated with the rest of the brain network in OAs. Critically, this age-related increase in PFC integration was associated with better retrieval performance. Second, PFC regions showed stronger performance-related reconfiguration of connectivity patterns in OAs. Finally, the PFC reconfiguration increases in OAs tracked reconfiguration reductions in the medial temporal lobe (MTL)-a core episodic memory region, suggesting that PFC connectivity in OAs may be compensating for MTL deficits.

Neurocognitive development of flanker and Stroop interference control: A near-infrared spectroscopy study

The abilities to resolve flanker and Stroop interference, which are primarily mediated by the prefrontal cortex (PFC), have been shown to be dissociable at the individual difference level. However, the relationship between the neurocognitive development of these two aspects of interference control remains unclear. This study examined developmental changes in inhibition performance and PFC activation during flanker and Stroop interference control using functional near-infrared spectroscopy (fNIRS). Twenty-eight healthy children and adolescents aged 7–16 years (16 males) underwent the arrow flanker and color-word matching Stroop paradigms while changes in oxyhemoglobin concentration in the PFC were monitored by fNIRS. We found developmental improvements in inhibition performance in terms of the interference scores on both the flanker and Stroop tasks. There were also developmental increases in PFC activation, particularly in the medial region, while resolving flanker and Stroop interference. Despite developmental changes in inhibition performance and medial PFC activation during both tasks, the developmental changes that we observed for these two aspects of interference control were found to be relatively independent of each other. Our findings support the heterogeneous view of interference control and suggest that the neurocognitive development of flanker and Stroop interference control is only weakly associated, if not dissociable.

Levodopa Facilitates Prefrontal Cortex Activation During Dual Task Walking in Parkinson Disease

Background. Although dopaminergic medication improves dual task walking in people with Parkinson disease (PD), the underlying neural mechanisms are not yet fully understood. As prefrontal cognitive resources are involved in dual task walking, evaluation of the prefrontal cortex (PFC) is required. Objective. To investigate the effect of dopaminergic medication on PFC activity and gait parameters during dual task walking in people with PD. Methods. A total of 20 individuals with PD (69.8 ± 5.9 years) and 30 healthy older people (68.0 ± 5.6 years) performed 2 walking conditions: single and dual task (walking while performing a digit vigilance task). A mobile functional near infrared spectroscopy system and an electronic sensor carpet were used to analyze PFC activation and gait parameters, respectively. Relative concentrations of oxygenated hemoglobin (HbO2) from the left and right PFC were measured. Results. People with PD in the off state did not present changes in HbO2 level in the left PFC across walking conditions. In contrast, in the on state, they presented increased HbO2 levels during dual task compared with single task. Regardless of medication state, people with PD presented increased HbO2 levels in the right PFC during dual task walking compared with single task. The control group demonstrated increased PFC activity in both hemispheres during dual task compared with single task. People with PD showed increases in both step length and velocity in the on state compared with the off state. Conclusions. PD limits the activation of the left PFC during dual task walking, and dopaminergic medication facilitates its recruitment.

Evaluation of neurocognitive function of prefrontal cortex in ornithine transcarbamylase deficiency

Hyperammonia due to ornithine transcarbamylase deficiency (OTCD) can cause a range of deficiencies in domains of executive function and working memory. Only a few fMRI studies have focused on neuroimaging data in a population with OTCD. Yet, there is a need for monitoring the disease progression and neurocognitive function in this population. In this study, we used a non-invasive neuroimaging technique, functional Near Infrared Spectroscopy (fNIRS), to examine the hemodynamics of prefrontal cortex (PFC) based on neural activation in an OTCD population. Using fNIRS, we measured the activation in PFC of the participants while performing the Stroop task. Behavioral assessment such as reaction time and correct response were recorded. We investigated the difference in behavioral measures as well as brain activation in left and right PFC in patients with OTCD and controls. Results revealed a distinction in left PFC activation between controls and patients with OTCD, where control subjects showed higher task related activation increase. Subjects with OTCD also exhibited bilateral increase in PFC activation. There was no significant difference in response time or correct response between the two groups. Our findings suggest the alterations in neurocognitive function of PFC in OTCD compared to the controls despite the behavioral profiles exhibiting no such differences. This is a first study using fNIRS to examine a neurocognitive function in OTCD population and can provide a novel insight into the screening of OTCD progression and examining neurocognitive changes.

Effect of Gum Chewing on PFC Activity During Discomfort Sound Stimulation.

The prefrontal cortex (PFC) is sensitive to the stress exposure and involved in stress coping. And the effects of gum chewing on the stress have been studied using NIRS. However, when measuring NIRS on PFC during gum chewing, blood flows in shallow tissues (scalp, skin, muscle) might be affected. A NIRS used in the present study first, which has a short distance (1cm) and the usual (3cm) source-detector (S-D) regression, can allow eliminating shallow tissues effect of gum chewing. The aim of this study was to investigate the hypothesis that gum chewing activates the right prefrontal cortex (PFC) in stress coping against negative sounds (NS) from the International Affective Digitized Sounds-2 (IADS) as a mental stress task. NS showed activation in the right PFC. There was a significant difference between NS, and NS with Gum, where NS with Gum showed an increased PFC activity, increased alpha wave appearance rate, a higher value in heart rate level, and a higher VAS score indicating 'pleasant'. Gum chewing activated right PFC activity while exposed to negative sounds from IADS as a mental stress task.

The Association between Prefrontal Cortex Activity and Turning Behavior in People with and without Freezing of Gait

Turning elicits Freezing of Gait (FoG) episodes in people with Parkinson's disease (PD) and is thought to require higher cortical control compared to straight ahead gait. Functional near infrared spectroscopy (fNIRS) has been used to examine prefrontal cortex (PFC) activity while walking, but the relationship between PFC activity and turn performance remains unclear. The aim of this pilot study was to examine PFC activity during turning in PD and healthy controls, and to investigate the association between PFC activity and turning.Thirty-two subjects, 15 freezers (PD + FoG) and 17 non-freezers (PD − FoG), and 8 controls were asked to perform a 2-min turning-in-place test under single-task (ST) and dual-task (DT) conditions. Each participant wore an fNIRS system to measure changes in oxyhemoglobin, as measure of PFC activity, and inertial sensors to quantify turning.Our results show a significant group (p = .050), task (p = .039), and interaction (p = .047) for the PFC activity during turning. Specifically, PD + FoG show higher PFC during turning compared to the other groups; PFC activity during DT is overall different compared to ST with an opposite trend in PD + FoG compared to controls and PD − FoG. In addition, higher PFC is associated with worse FoG in PD + FoG (r = 0.57, p = .048) and with lower number of turns in PD − FoG (r = −0.70, p = .002).The increased PFC activity in PD and the association between higher PFC activity and poorer turning performance may be a sign of poor movement automaticity in PD. Although further investigations are required, these pilot findings may guide development of personalized treatments to improve motor automaticity in PD.

Delta-9-tetrahydrocannabinol intoxication is associated with increased prefrontal activation as assessed with functional near-infrared spectroscopy: A report of a potential biomarker of intoxication

The primary psychoactive compound in cannabis, Δ9-tetrahydrocannabinol (THC), binds to cannabinoid receptors (CB1) present in high concentrations in the prefrontal cortex (PFC). It is unknown whether the PFC hemodynamic response changes with THC intoxication. We conducted the first double-blind, placebo-controlled, cross-over study of the effect of THC intoxication on functional near infrared spectroscopy (fNIRS) measures of PFC activation. Fifty-four adult, regular (at least weekly) cannabis users received a single oral dose of synthetic THC (dronabinol; 5–50 mg, dose individually tailored to produce intoxication) and identical placebo on two visits at least one week apart. fNIRS recordings were obtained during a working memory task (N-Back) at three timepoints: before THC/placebo, at 100 min (when peak effects were expected), and at 200 min after THC/placebo administration. Functional data were collected using a continuous-wave NIRS device, with 8 sources and 7 detectors arrayed over the forehead, resulting in 20 channels covering PFC regions. Participants also completed frequent heart rate measures and subjective ratings of intoxication. Approximately half of participants reported significant intoxication. Intoxication ratings were not correlated with dose of THC. Increases in heart rate significantly correlated with intoxication ratings after THC dosing. Results indicated that 100 min after THC administration, oxygenated hemoglobin (HbO) response significantly increased from pre-dose HbO levels throughout the PFC in participants who reported significant intoxication. Changes in HbO response significantly correlated with self-reported intoxication at 100 min after THC administration. Among those who reported intoxication, HbO response decreased at 200 min after THC, when intoxication had largely resolved, compared to the peak THC time point. This study demonstrates that THC intoxication causes increased PFC activity, and fNIRS of the PFC can measure this effect. Increased neural activation in PFC represents a potential biomarker for cannabis intoxication.