Changes In Blood Oxygenation Level Research Articles

Abnormal resting-state hyperconnectivity in schizophrenia: A whole-head near-infrared spectroscopy study

Near-infrared spectroscopy (NIRS) is a noninvasive functional neuroimaging modality that can detect changes in blood oxygenation levels by tracking cortical neural activity. We recorded the resting-state brain activity of 24 individuals with schizophrenia and 90 healthy controls for 8 min using a whole-head NIRS arrangement and then used partial correlation analysis to estimate the resting-state functional connectivity (RSFC) between 17 cortical regions. We found that the RSFC between the bilateral orbitofrontal cortices (OFCs) and between the right temporal and parietal lobes was significantly higher in patients with schizophrenia than in healthy controls. The RSFC between the bilateral OFCs was positively correlated with negative symptom severity, whereas the RSFC between the right temporal and parietal lobes was positively correlated with the chlorpromazine equivalent for antipsychotics prescribed to patients with schizophrenia. This finding was consistent with that for the RSFC calculated using the anterior 52-channel signals. Our results suggest that NIRS-based RSFC measurements have potential clinical applications.

A new classification for emergency critically ill patients and analysis of their adverse events during intrahospital transport: A cluster analysis.

Critical patients may experience various adverse events during transportation within hospitals. Therefore, quickly evaluating and classifying patients before transporting them from the emergency department and focusing on managing high-risk patients are critical. At present, no unified classification method exists; all the current approaches are subjective. To ensure transportation safety, we conducted a cluster analysis of critically ill patients transferred from the emergency department to the intensive care unit. Single-centre cohort study. This study was conducted at a comprehensive first-class teaching hospital in Beijing. Convenience sampling and continuous enrolment were employed. We collected data from 1 January 2019, to 31 December 2021. All patients were transferred from the emergency department to the intensive care unit, and cluster analysis was conducted using five variables. A total of 584 patients were grouped into three clusters. Cluster 1 (high systolic blood pressure group) included 208 (35.6%) patients. Cluster 2 (high heart rate and low blood oxygen group) included 55 (9.4%) patients. Cluster 3 (normal group) included the remaining 321 (55%) patients. The oxygen saturation levels of all the patients were lower after transport, and the proportion of adverse events (61.8%) was the highest in Cluster 2 (p < .05). This study utilized data on five important vital signs from a cluster analysis to explore possible patient classifications and provide a reference for ensuring transportation safety. Before transferring patients, we should classify them and implement targeted care. Changes in blood oxygen levels in all patients should be considered, with a focus on the occurrence of adverse events during transportation among patients with high heart rates and low blood oxygen levels.

Study of Motion Sickness Model Based on fNIRS Multiband Features during Car Rides

Motion sickness is a common physiological discomfort phenomenon during car rides. In this paper, the functional near-infrared spectroscopy (fNIRS) technique was used in real-world vehicle testing. The fNIRS technique was utilized to model the relationship between changes in blood oxygenation levels in the prefrontal cortex of passengers and motion sickness symptoms under different motion conditions. To enhance the accuracy of motion sickness classification, the study utilized principal component analysis (PCA) to extract the most significant features from the test data. Wavelet decomposition was used to extract the power spectrum entropy (PSE) features of five frequency bands highly related to motion sickness. The correlation between motion sickness and cerebral blood oxygen levels was modeled by a 6-point scale calibration for the subjective evaluation of the degree of passenger motion sickness. A support vector machine (SVM) was used to build a motion sickness classification model, achieving an accuracy of 87.3% with the 78 sets of data. However, individual analysis of the 13 subjects showed a varying range of accuracy from 50% to 100%, suggesting the presence of individual differences in the relationship between cerebral blood oxygen levels and motion sickness symptoms. Thus, the results demonstrated that the magnitude of motion sickness during the ride was closely related to the change in the PSE of the five frequency bands of cerebral prefrontal blood oxygen, but further studies are needed to investigate individual variability.

Searching for the Mechanism of Action of Extremely Low Frequency Electromagnetic Field-The Pilot fNIRS Research.

There is an ongoing debate on the benefits of magnetic stimulation in neurological disorders. Objectives: We aimed to evaluate the influence of magnetic stimulation on blood oxygenation of the motor cortex using functional near-infrared spectroscopy (fNIRS). Methods: A total of 16 healthy volunteer participants were subjected to four protocols. In the first two protocols, the participants remained at rest without (and then with) magnetic stimulation. In the next two protocols, motor cortex stimulation was achieved using a finger-tapping task, with and without magnetic stimulation. Changes in blood oxygenation levels within the motor cortex were recorded and analysed. Results: No characteristic changes in the blood oxygenation level-dependent responses were observed in resting participants after magnetic stimulation. No statistically significant difference was observed in the amplitude of the fNIRS signal before and after magnetic stimulation. We observed characteristic blood oxygenation level-dependent responses after the finger-tapping task in the second protocol, but not after magnetic stimulation. Conclusions: Although we did not observe any measurable effect of the magnetic field on the haemodynamic response of the motor cortex, understanding the mechanism(s) of magnetic stimulation may be important. Additional, detailed studies are needed to prove or negate the potential of this medical procedure.

Hemodynamic responses are abnormal in isolated cervical dystonia.

Neuroimaging studies using functional magnetic resonance imaging (fMRI), which measures brain activity by detecting the changes in blood oxygenation levels, are advancing our understanding of the pathophysiology of dystonia. Neurobiological disturbances in dystonia, however, may affect neurovascular coupling and impact the interpretability of fMRI studies. We evaluated here whether the hemodynamic response patterns during a behaviorally matched motor task are altered in isolated cervical dystonia (CD). Twenty-five CD patients and 25 healthy controls (HCs) underwent fMRI scanning during a paced finger tapping task (nondystonic task in patients). Imaging data were analyzed using a constrained principal component analysis-a statistical method that combines regression analysis and principal component analysis and enables the extraction of task-related functional networks and determination of the spatial and temporal hemodynamic response patterns associated with the task performance. Data from three patients and two controls were removed due to excessive movement. No significant differences in demographics or motor performance were observed. Three task-associated functional brain networks were identified. During task performance, reduced hemodynamic responses were seen in a sensorimotor network and in a network that included key nodes of the default mode, executive control and visual networks. During rest, reductions in hemodynamic responses were seen in the cognitive/visual network. Lower hemodynamic responses within the primary sensorimotor network in patients were correlated with the increased dystonia severity. Pathophysiological disturbances in isolated CD, such as alterations in inhibitory signaling and dopaminergic neurotransmission, may impact neurovascular coupling. Not accounting for hemodynamic response differences in fMRI studies of dystonia could lead to inaccurate results and interpretations.

Functional spectroscopic imaging reveals specificity of glutamate response in mouse brain to peripheral sensory stimulation

Non-invasive investigation of physiological changes and metabolic events associated with brain activity in mice constitutes a major challenge. Conventionally, fMRI assesses neuronal activity by evaluating activity-evoked local changes in blood oxygenation levels (BOLD). In isoflurane-anaethetized mice, however, we found that BOLD signal changes during paw stimulation appear to be dominated by arousal responses even when using innocuous stimuli. Widespread responses involving both hemispheres have been observed in response to unilateral stimulation. MRS allows probing metabolic changes associated with neuronal activation and provides a complementary readout to BOLD fMRI for investigating brain activity. In this study we evaluated the sensitivity of a free induction decay (FID) based spectroscopic imaging (MRSI) protocol for the measurement of alterations in glutamate levels elicited by unilateral electrical paw stimulation at different current amplitudes. Coronal MRSI maps of glutamate distribution with 17 × 17 voxels of 1 µl volume have been recorded with a temporal resolution of 12 min. Significant region-specific increases in glutamate levels have been observed in the contralateral but not in the ispiateral S1 somatosensory cortex upon stimulation. The amplitude of glutamate changes increased in a dose-dependent manner with the stimulus amplitude. The study demonstrates feasibility of functional MRSI in mice for studying activity-evoked glutamate changes in a temporo-spatially resolved manner.

Acute oxygen sensing by the carotid body: from mitochondria to plasma membrane.

Maintaining oxygen homeostasis is crucial to the survival of animals. Mammals respond acutely to changes in blood oxygen levels by modulating cardiopulmonary function. The major sensor of blood oxygen that regulates breathing is the carotid body (CB), a small chemosensory organ located at the carotid bifurcation. When arterial blood oxygen levels drop in hypoxia, neuroendocrine cells in the CB called glomus cells are activated to signal to afferent nerves that project to the brain stem. The mechanism by which hypoxia stimulates CB sensory activity has been the subject of many studies over the past 90 years. Two discrete models emerged that argue for the seat of oxygen sensing to lie either in the plasma membrane or mitochondria of CB cells. Recent studies are bridging the gap between these models by identifying hypoxic signals generated by changes in mitochondrial function in the CB that can be sensed by plasma membrane proteins on glomus cells. The CB is important for physiological adaptation to hypoxia, and its dysfunction contributes to sympathetic hyperactivity in common conditions such as sleep-disordered breathing, chronic heart failure, and insulin resistance. Understanding the basic mechanism of oxygen sensing in the CB could allow us to develop strategies to target this organ for therapy. In this short review, I will describe two historical models of CB oxygen sensing and new findings that are integrating these models.

Vibration over the larynx increases swallowing and cortical activation for swallowing

Sensory input can alter swallowing control in both the cortex and brainstem. Electrical stimulation of superior laryngeal nerve afferents increases reflexive swallowing in animals, with different frequencies optimally effective across species. Here we determined 1) if neck vibration overlying the larynx affected the fundamental frequency of the voice demonstrating penetration of vibration into the laryngeal tissues, and 2) if vibration, in comparison with sham, increased spontaneous swallowing and enhanced cortical hemodynamic responses to swallows in the swallowing network. A device with two motors, one over each thyroid lamina, delivered intermittent 10-s epochs of vibration. We recorded swallows and event-related changes in blood oxygenation level to swallows over the motor and sensory swallowing cortexes bilaterally using functional near infrared spectroscopy. Ten healthy participants completed eight 20-min conditions in counterbalanced order with either epochs of continuous vibration at 30, 70, 110, 150, and 70 + 110 Hz combined, 4-Hz pulsed vibration at 70 + 110 Hz, or two sham conditions without stimulation. Stimulation epochs were separated by interstimulus intervals varying between 30 and 45 s in duration. Vibration significantly reduced the fundamental frequency of the voice compared with no stimulation demonstrating that vibration penetrated laryngeal tissues. Vibration at 70 and at 150 Hz increased spontaneous swallowing compared with sham. Hemodynamic responses to swallows in the motor cortex were enhanced during conditions containing stimulation compared with sham. As vibratory stimulation on the neck increased spontaneous swallowing and enhanced cortical activation for swallows in healthy participants, it may be useful for enhancing swallowing in patients with dysphagia.NEW & NOTEWORTHY Vibratory stimulation at 70 and 150 Hz on the neck overlying the larynx increased the frequency of spontaneous swallowing. Simultaneously vibration also enhanced hemodynamic responses in the motor cortex to swallows when recorded with functional near-infrared spectroscopy (fNIRS). As vibrotactile stimulation on the neck enhanced cortical activation for swallowing in healthy participants, it may be useful for enhancing swallowing in patients with dysphagia.

Frontal temporal and parietal systems synchronize within and across brains during live eye-to-eye contact

Human eye-to-eye contact is a primary source of social cues and communication. In spite of the biological significance of this interpersonal interaction, the underlying neural processes are not well-understood. This knowledge gap, in part, reflects limitations of conventional neuroimaging methods, including solitary confinement in the bore of a scanner and minimal tolerance of head movement that constrain investigations of natural, two-person interactions. However, these limitations are substantially resolved by recent technical developments in functional near-infrared spectroscopy (fNIRS), a non-invasive spectral absorbance technique that detects changes in blood oxygen levels in the brain by using surface-mounted optical sensors. Functional NIRS is tolerant of limited head motion and enables simultaneous acquisitions of neural signals from two interacting partners in natural conditions. We employ fNIRS to advance a data-driven theoretical framework for two-person neuroscience motivated by the Interactive Brain Hypothesis which proposes that interpersonal interaction between individuals evokes neural mechanisms not engaged during solo, non-interactive, behaviors. Within this context, two specific hypotheses related to eye-to-eye contact, functional specificity and functional synchrony, were tested. The functional specificity hypothesis proposes that eye-to-eye contact engages specialized, within-brain, neural systems; and the functional synchrony hypothesis proposes that eye-to-eye contact engages specialized, across-brain, neural processors that are synchronized between dyads. Signals acquired during eye-to-eye contact between partners (interactive condition) were compared to signals acquired during mutual gaze at the eyes of a picture-face (non-interactive condition). In accordance with the specificity hypothesis, responses during eye-to-eye contact were greater than eye-to-picture gaze for a left frontal cluster that included pars opercularis (associated with canonical language production functions known as Broca's region), pre- and supplementary motor cortices (associated with articulatory systems), as well as the subcentral area. This frontal cluster was also functionally connected to a cluster located in the left superior temporal gyrus (associated with canonical language receptive functions known as Wernicke's region), primary somatosensory cortex, and the subcentral area. In accordance with the functional synchrony hypothesis, cross-brain coherence during eye-to-eye contact relative to eye-to-picture gaze increased for signals originating within left superior temporal, middle temporal, and supramarginal gyri as well as the pre- and supplementary motor cortices of both interacting brains. These synchronous cross-brain regions are also associated with known language functions, and were partner-specific (i.e., disappeared with randomly assigned partners). Together, both within and across-brain neural correlates of eye-to-eye contact included components of previously established productive and receptive language systems. These findings reveal a left frontal, temporal, and parietal long-range network that mediates neural responses during eye-to-eye contact between dyads, and advance insight into elemental mechanisms of social and interpersonal interactions.

Detection of resting state functional connectivity using partial correlation analysis: A study using multi-distance and whole-head probe near-infrared spectroscopy

Multichannel near-infrared spectroscopy (NIRS) is a functional neuroimaging modality that enables easy-to-use and noninvasive measurement of changes in blood oxygenation levels. We developed a clinically-applicable method for estimating resting state functional connectivity (RSFC) with NIRS using a partial correlation analysis to reduce the influence of extraneural components. Using a multi-distance probe arrangement NIRS, we measured resting state brain activity for 8min in 17 healthy participants. Independent component analysis was used to extract shallow and deep signals from the original NIRS data. Pearson's correlation calculated from original signals was significantly higher than that calculated from deep signals, while partial correlation calculated from original signals was comparable to that calculated from deep (cerebral-tissue) signals alone. To further test the validity of our method, we also measured 8min of resting state brain activity using a whole-head NIRS arrangement consisting of 17 cortical regions in 80 healthy participants. Significant RSFC between neighboring, interhemispheric homologous, and some distant ipsilateral brain region pairs was revealed. Additionally, females exhibited higher RSFC between interhemispheric occipital region-pairs, in addition to higher connectivity between some ipsilateral pairs in the left hemisphere, when compared to males. The combined results of the two component experiments indicate that partial correlation analysis is effective in reducing the influence of extracerebral signals, and that NIRS is able to detect well-described resting state networks and sex-related differences in RSFC.

Within- and Between-Session Changes in Neural Activity During Emotion Processing in Unipolar and Bipolar Depression

BackgroundBipolar disorder (BD) and unipolar depression (UD) can be difficult to distinguish clinically, particularly during episodes of depression. In this study, we test for differences between adults with BD, adults with UD, and healthy control (HC) adults regarding within-session and between-session changes in blood oxygen level–dependent (BOLD) response during implicit emotional processing. MethodsDuring functional magnetic resonance imaging, HC adults (n = 19) and adults with UD (n = 19) and BD (n = 16) performed an implicit emotion processing task. Each participant was scanned twice, separated by 6 months, resulting in 108 scans. The BOLD response and linear change in BOLD response were examined within and between sessions. ResultsWe observed within-session linear decreases in BOLD signal (regardless of group, condition, or session) in the left amygdala, a right-sided temporoparietal region, and a right-sided frontoinsular region. We also observed group differences in within-session BOLD signal change (p < .05, familywise error corrected) in a left-sided striatoinsular-thalamic region. Adults with BD demonstrated a linear decrease in BOLD signal compared with HC adults (p < .008, familywise error corrected) across this region and compared with adults with UD in the posterior insula portion of the region (p < .008, familywise error corrected). Finally, we observed main effects of emotional valence in bilateral visuospatial processing regions as well as in the left and right amygdala. ConclusionsAdults with BD demonstrated linear attenuation of BOLD response to emotional stimuli within left-sided striatoinsular-thalamic regions. Adults with BD may either have experienced abnormal habituation in this region or have disengaged quickly from processing the emotional stimuli, despite comparable task performance. This pattern may represent an underlying pathophysiologic process associated with BD that differs from UD.

A method to analyze low signal-to-noise ratio functional magnetic resonance imaging data.

The current practice of using a single, representative hemodynamic response function (canonical HRF) to model functional magnetic resonance imaging (fMRI) data is questionable given the trial-to-trial variability of the brain's responses. In addition, the changes in blood-oxygenation level due to sensory stimulation may be small, especially when auditory stimuli are used. Here we introduce a correlation-based single trial analysis method for fMRI data analysis to deal with the low signal-to-noise (SNR) ratio and variability of the HRF in response to repeated, identical auditory stimuli. The correlation technique identifies the "active" trials, i.e., those showing a robust hemodynamic response among all single trials. Using data collected from 14 healthy subjects, it was found that the correlation method can find significant differences between brain areas and brain states in actual fMRI data. Also, the correlation-based method confirmed that the superior temporal gyrus (STG), inferior frontal gyrus (IFG), dorsolateral prefrontal cortex (DLPFC) and thalamus (THA) are involved in auditory information processing in general, and the involvement of the bilateral STG, right THA and left DLPFC in sensory gating. In contrast, conventional analysis failed to find any regions involved in sensory gating. The findings suggest that our single trial analysis method can increase the sensitivity of fMRI data analysis.

Multispectral opto-acoustic tomography of exercised muscle oxygenation

Unlike near-infrared spectroscopy, multispectral opto-acoustic tomography (MSOT) has the potential to offer high-resolution imaging assessment of hemodynamics and blood saturation levels in muscle. However motion artifacts impede the real-time applications of the technique. We developed fast-MSOT with motion tracking that reduces motion artifacts. We used this algorithm to follow blood oxygenation level changes associated with muscle exercise in the muscle and the skin of healthy volunteers.

Selective Expression of Galanin in Neuronal-Like Cells of the Human Carotid Body.

The carotid body is a neural-crest-derived organ devoted to respiratory homeostasis through sensing changes in blood oxygen levels. The sensory units are the glomeruli composed of clusters of neuronal-like (type I) cells surrounded by glial-like (type II) cells. During chronic hypoxia, the carotid body shows growth, with increasing neuronal-like cell numbers. We are interested in the signals involved in the mechanisms that underlie such response, because they are not well understood and described. Considering that, in literature, galanin is involved in neurotrophic or neuroprotective role in cell proliferation and is expressed in animal carotid body, we investigated its expression in human. Here, we have shown the expression and localisation of galanin in the human carotid body.

Observation on effect of meridian stimulation on blood oxygenation level of brain by applying Near Infra Red Spectrum (NIRS)

ObjectiveTo observe the effect of stimulating Yìntáng (▪ EX-HN 3) and Băihuì (▪ GV 20) with electroacupuncture (EA) on blood oxygenation level of brain and explore the feasibility of measuring the therapeutic effect of acupuncture by applying near infra red spectrum (NIRS). MethodsTen participants semi-randomly selected from 158 adults (random test sequence) were stimulated with EA at the acupoints of EX-HN 3 and GV 20. Verbal fluency task was conducted before and after acupuncture, and changes in blood oxygenation level of cerebral cortex were tested by applying NIRS. Quantitative data were processed with JMP 10.0.2 software, and changes in waveforms of blood oxygenation level of brain before and after treatment were compared by applying NIRS. Results▪ The mean of reacting dose (integral value) of blood oxygenation level of cerebral cortex of the 158 adults in the verbal fluency task was 10.6 ± 1.1, and the mean of the whole reacting dose of blood oxygenation level of cerebral cortex at 1/2 period of time during the test (centroids value) was 46.8 ± 1.6. ▪ In the EA group, the mean of integral value and centroids value of 10 adults were 8.4 ± 5.1 and 54.7 ± 12.2 before EA while 9.8±3.5 and 41.2±6.7 after EA. The integral value and centroids value of the EA group were closer to the mean of all the subjects. ConclusionIt was found by NIRS that the blood oxygenation level of cerebral cortex could be regulated in bidirectional way by stimulating EX-HN 3 and GV 20 with EA, and a further research on whether it directly related to EA is to be made.

Near-infrared spectroscopy based neurofeedback training increases specific motor imagery related cortical activation compared to sham feedback

In the present study we implemented a real-time feedback system based on multichannel near-infrared spectroscopy (NIRS). Prior studies indicated that NIRS-based neurofeedback can enhance motor imagery related cortical activation. To specify these prior results and to confirm the efficacy of NIRS-based neurofeedback, we examined changes in blood oxygenation level collected in eight training sessions. One group got real feedback about their own brain activity (N=9) and one group saw a playback of another person’s feedback recording (N=8). All participants performed motor imagery of a right hand movement. Real neurofeedback induced specific and focused brain activation over left motor areas. This focal brain activation became even more specific over the eight training sessions. In contrast, sham feedback led to diffuse brain activation patterns over the whole cortex. These findings can be useful when training patients with focal brain lesions to increase activity of specific brain areas for rehabilitation purpose.

In vivo measurement of oxygenation changes after stroke using susceptibility weighted imaging filtered phase data.

Background and PurposeCerebral blood oxygenation level is critical for following the evolution of stroke patients. The purpose of this study was to investigate the feasibility of measuring changes in blood oxygen levels for patients with acute stroke using SWI and to compare these changes with the patient's recovery over time.Materials and MethodsA total 30 MRI scans was performed on 10 acute ischemic stroke patients. Every patient was followed at three time points: less than 24 hours; 2–3 weeks after stroke and 2 months after stroke. Both MRI scan and NIH stroke scale (NIHSS) were acquired for each patient at all three time points. Oxygen saturation changes were derived from phase values differences (Δφ) measured over 10 veins from each hemisphere for all 10 patients over 3 time points. The correlation of oxygen saturation and NIHSS was further evaluated.ResultsThe stroke affected side of the brain showed moderate (r = −0.62) to strong (r = −0.70) correlation between the oxygenation change and NIHSS change. The oxygen saturation change from the normal side of the brain had essentially no association with recovery (r = −0.02 and−0.31). The results suggest that increases in oxygen saturation correspond to improved outcome and reductions in oxygen saturation correspond to worse outcome.ConclusionHigh resolution SWI provided a novel method to measure changes in oxygenation change of the human brain in vivo. By using the phase values from the veins, both spatial and temporal information can be found that relates to patient outcome post stroke.

Modulation of neural activation following treatment of hepatic encephalopathy

To measure changes in psychometric state, neural activation, brain volume (BV), and cerebral metabolite concentrations during treatment of minimal hepatic encephalopathy. As proof of principle, 22 patients with well-compensated, biopsy-proven cirrhosis of differing etiology and previous minimal hepatic encephalopathy were treated with oral l-ornithine l-aspartate for 4 weeks. Baseline and 4-week clinical review, blood chemistry, and psychometric evaluation (Psychometric Hepatic Encephalopathy Score and Cognitive Drug Research Score) were performed. Whole-brain volumetric and functional MRI was conducted using a highly simplistic visuomotor task, together with proton magnetic resonance spectroscopy of the basal ganglia. Treatment-related changes in regional BV and neural activation change (blood oxygenation level dependent) were assessed. Although there was no change in clinical, biochemical state, basal ganglia magnetic resonance spectroscopy, or in regional BV, there were significant improvements in Cognitive Drug Research Score (+1.2, p = 0.003) and Psychometric Hepatic Encephalopathy Score (+1.5, p = 0.003) with treatment. This cognitive amelioration was accompanied by changes in blood oxygenation level-dependent activation in the posterior cingulate and ventral medial prefrontal cortex, 2 regions that form part of the brain's structural and metabolic core. In addition, there was evidence of greater visual cortex activation. These structurally interconnected regions all showed increased function after successful encephalopathy treatment. Because no regional change in BV was observed, this implies that mechanisms unrelated to astrocyte volume regulation were involved in the significant improvement in cognitive performance.

Motor Neglect and Future Directions for Research

Motor Neglect and Future Directions for Research

Neural Correlates of Weight Gain With Olanzapine

CONTEXT Iatrogenic obesity caused by atypical antipsychotics increases the rate of death from all causes. Olanzapine is a commonly prescribed atypical antipsychotic medication that frequently causes weight gain. To our knowledge, the neural correlates of this weight gain have not been adequately studied in humans. OBJECTIVE To test the hypothesis that olanzapine treatment disrupts the neural activity associated with the anticipation and receipt (consumption) of food rewards (chocolate milk and tomato juice). DESIGN Event-related functional magnetic resonance imaging study, before and after a 1-week treatment with olanzapine. SETTING A university neuroimaging center. PARTICIPANTS Twenty-five healthy individuals. MAIN OUTCOME MEASURES Changes in blood oxygen level-dependent activations to the anticipation and receipt of food rewards after olanzapine treatment. RESULTS One week of olanzapine treatment caused significant increases in weight, food consumption, and disinhibited eating. Our imaging data showed enhanced activations in the inferior frontal cortex, striatum, and anterior cingulate cortex to the anticipation of a food reward. Activation in the caudate and putamen were enhanced to the receipt of the rewarding food. We also found a decrease in reward responsivity to receipt of the rewarding food in the lateral orbital frontal cortex, an area of the brain thought to exercise inhibitory control on feeding. CONCLUSIONS Olanzapine treatment enhanced both the anticipatory and consummatory reward responses to food rewards in the brain reward circuitry that is known to respond to food rewards in healthy individuals. We also noted a decrease in responsivity to food consumption in a brain area thought to inhibit feeding behavior.