Biomedical subjects

Jim Lagopoulos

Publications and source records attributed to Jim Lagopoulos.

14 recordsLinked to original sources

PubMed2006

Reduced activation to implicit affect induction in euthymic bipolar patients: an fMRI study.

OBJECTIVE: To examine whether euthymic bipolar patients engage similar or contrasting brain regions as healthy subjects when responding to implicit affect induction. METHODS: The study examined 10 euthymic patients with bipolar I disorder, and 10 age- and gender-matched healthy subjects using event-related functional magnetic resonance imaging (fMRI) while subjects engaged in a modified word-based memory task designed to implicitly evoke negative, positive or no affective change. The activation paradigm involved nominating whether a target word was contained within a previously presented word list using specified response keys. RESULTS: The fMRI task produced significantly greater activation in healthy subjects as compared to patients in response to both negative and positive affect in the anterior and posterior cingulate, medial prefrontal cortex, middle frontal and right parahippocampal gyri. Only negative affect produced significantly greater activation in the postcentral gyrus, inferior parietal lobule, thalamus and putamen and only positive affect achieved the same in the precentral, superior temporal and lingual gyri, precuneus, cuneus, caudate, pons, midbrain and cerebellum. There were no brain regions in which responses were greater in patients as compared to healthy subjects. There were no statistically significant differences between the groups with respect to speed or accuracy. CONCLUSIONS: Diminished prefrontal, cingulate, limbic and subcortical neural activity in euthymic bipolar patients as compared to healthy subjects is suggestive of emotional compromise that is independent of cognitive and executive functioning. This finding is of clinical importance and has implications both for the diagnosis and treatment of bipolar disorder. Future studies should aim to replicate these findings and examine the development of bipolar disorder, investigating in particular the effects of medication.

Adult↗

PubMed2006

Transient loss of motor-evoked responses associated with caudal injection of morphine in a patient with spondylolisthesis undergoing spinal fusion.

A 7-year-old girl having posterior spinal fusion for Grade 3 anterior spondylolisthesis at the L5/S1 level was administered 2.5 mg of morphine in 10 ml saline via the caudal epidural route before surgery. Motor-evoked responses were markedly diminished in her lower limbs for 1 h following this but returned spontaneously. She suffered no neurological injury. The cause for this is postulated to be transient cauda equina compression from the volume of injectate. This complication of caudal injection has not been reported before. The possible mechanisms for this are discussed. We believe that significant L5/S1 spondylolisthesis should be considered a contraindication to the use of caudal epidural injections.

Analgesics, Opioid↗

PubMed2006

Cognitive compromise in bipolar disorder with chronic cannabis use: cause or consequence?

This article briefly reviews the neuropsychological deficits associated with bipolar disorder and examines how substance abuse, in particular chronic cannabis use, may contribute to these. The focus of the article is cannabis, owing to its popularity in patients with bipolar disorder, although many studies focus on its use in conjunction with other substances. The findings are contextualized within bipolar disorder, examining functional outcome.

Bipolar Disorder↗

PubMed2005

Functional MRI BOLD response to Tower of London performance of first-episode schizophrenia patients using cortical pattern matching.

Due to its three-dimensional folding pattern, the human neocortex poses a challenge for accurate co-registration of grouped functional brain imaging data. The present study addressed this problem by employing three-dimensional continuum-mechanical image-warping techniques to derive average anatomical representations for co-registration of functional magnetic resonance brain imaging data obtained from 10 male first-episode schizophrenia patients and 10 age-matched male healthy volunteers while they performed a version of the Tower of London task. This novel technique produced an equivalent representation of blood oxygenation level dependent (BOLD) response across hemispheres, cortical regions, and groups, respectively, when compared to intensity average co-registration, using a deformable Brodmann area atlas as anatomical reference. Somewhat closer association of Brodmann area boundaries with primary visual and auditory areas was evident using the gyral pattern average model. Statistically-thresholded BOLD cluster data confirmed predominantly bilateral prefrontal and parietal, right frontal and dorsolateral prefrontal, and left occipital activation in healthy subjects, while patients' hemispheric dominance pattern was diminished or reversed, particularly decreasing cortical BOLD response with increasing task difficulty in the right superior temporal gyrus. Reduced regional gray matter thickness correlated with reduced left-hemispheric prefrontal/frontal and bilateral parietal BOLD activation in patients. This is the first study demonstrating that reduction of regional gray matter in first-episode schizophrenia patients is associated with impaired brain function when performing the Tower of London task, and supports previous findings of impaired executive attention and working memory in schizophrenia.

Adolescent↗

PubMed2005

Cerebral autoregulation and ageing.

Little is known about the effects of ageing on cerebral autoregulation (CA). To examine the relationship between age and CA in adults, we conducted a prospective study using a non-invasive protocol without external stimuli. We studied 32 subjects, aged 23-68 years. They were assigned to a young group (28+/-5 years) and an old group (54+/-8 years). The groups were sex-matched. Transcranial Doppler ultrasonography (TCD) was used to record bilateral middle cerebral artery flow velocities (CBFV, cm/sec). Noninvasive beat-to-beat tonometric arterial blood pressure (ABP) measurement of the radial artery was used to record spontaneous blood pressure fluctuations. The Mx, an index of dynamic cerebral autoregulation (dCA), was calculated from a moving correlation between ABP and CBFV. We did not find a correlation between age and Mx. No statistically significant difference in the Mx between the groups (0.27+/-0.23, young, vs. 0.37+/-0.24, old) was demonstrated. Age does not affect dynamic cerebral autoregulation assessed by the Mx index in healthy adult subjects. This study supports findings from previous papers wherein CA was measured with protocols which require external stimuli. Further studies are needed to determine CA in subjects above 70 years of age.

Adult↗

PubMed2005

When euthymia is just not good enough: the neuropsychology of bipolar disorder.

Bipolar disorder (BD) is a debilitating psychiatric illness that is uniquely characterized by switching between psychopathologically contrasting phases of mania and depression, often with intervening periods of euthymia. However, these periods of apparent clinical recovery (euthymia) are marked by subtle social, occupational, and cognitive impairments, profiled by recent neuropsychological investigations. Determining the cognitive changes across these three phases may help differentiate the disruptions that are mood state-dependent from those associated with underlying pathology. This article therefore critically reviews the reported neuropsychological impairments in BD and the methodological limitations facing such research. Integration of the available evidence, principally from the field of neuropsychology, when synthesized, implicates the prefrontal cortex in the etiopathogenesis of BD and posits cortical-subcortical-limbic disruption in recovered euthymic patients that manifests as cognitive dysfunction.

Bipolar Disorder↗

PubMed2005

An emotional Stroop functional MRI study of euthymic bipolar disorder.

OBJECTIVE: To identify the brain regions associated with emotional processing in euthymic bipolar patients. METHODS: The study examined 12 euthymic bipolar patients using functional magnetic resonance imaging (fMRI) while performing an emotional Stroop (eStroop) task. The task comprised emotionally valent and neutral words presented in alternating blocks that was designed to implicitly induce affect. In conjunction with fMRI, galvanic skin responses (GSR) were measured to monitor arousal. RESULTS: Euthymic bipolar patients had diminished activation in response to the affective stimuli in both cortical and subcortical brain regions when compared with healthy subjects. In particular, patients had less activation in the left ventral prefrontal cortex suggesting a potential trait deficit. Patients were slower to react than healthy controls, but did not differ with respect to accuracy. CONCLUSIONS: Euthymic bipolar patients are perhaps constrained in their ability to engage affective processing. Diminished ventral prefrontal cortex activation corroborates previous reports of a potential trait deficit, suggesting that 'all is not well in euthymia', although the effects of medication cannot be overlooked.

Adult↗

PubMed2005

A matter of motion or an emotional matter? Management of depression in Parkinson's disease.

Depression is one of the most frequent comorbidities occurring in Parkinson's disease, affecting up to 50% of patients. Depression is associated with severe negative symptoms and has been shown to contribute to an increased rate of decline of both cognitive and motor function, profoundly impacting on the patient's quality of life. The symptoms of depression overlap with the motor features of Parkinson's disease, making detection difficult. Moreover, the lack of specialized screening tools means that depression remains undiagnosed and untreated in a high percentage of patients. However, depression in Parkinson's disease, when identified early, can be effectively treated with a variety of antidepressant medications, improving quality of life and preserving daily function. The focus of this review is to provide an overview of current knowledge regarding depression in Parkinson's disease, followed by a practical discussion addressing the issues of the detection, diagnosis and treatment.

Antidepressive Agents↗

PubMed2005

A fiber-optic system for recording skin conductance in the MRI scanner.

The acquisition of the skin conductance response (SCR) during functional magnetic resonance imaging (fMRI) raises significant safety issues, as well as practical ones, which need to be addressed in order for these experiments to be conducted safely and successfully. Metallic and conductive wires in the presence of time-varying gradient magnetic fields such as those present in fMRI experiments may induce heating, as well as electric fields, in these components and, if in contact with the subject, could produce severe burns and electric shocks. Moreover, these metallic and conductive components can significantly distort the magnetic field, resulting in image artifacts. A system for recording the SCR in humans simultaneously with fMRI is presented. The device is a fiber-optic-based transducer, which records the SCR from two fingers of the same hand, using electrodes containing inline radio frequency (RF) suppression filters and protective resistive loads. The fiber-optic SCR transducer was tested using 1.5 and 3.0 Tesla MRI scanners running EPI sequences. This system was able to safely record SCRs free of RF interference during an fMRI experiment, and the fiber-optic design of the transducer eliminated any artifacts on the MRI scan.

Brain↗

PubMed2004

Cognitive generation of affect in bipolar depression: an fMRI study.

Individuals with bipolar disorder manifest the full spectrum of emotions ranging from depression to mania. In attempting to understand the functional substrates of mood we attempted to identify brain regions associated with the cognitive generation of affect in bipolar depressed patients. We therefore examined ten depressed female subjects with bipolar affective disorder, and ten age-matched and sex-matched healthy comparison subjects using functional magnetic resonance imaging (fMRI) while viewing alternating blocks of captioned pictures designed to evoke negative, positive or no affective change. The activation paradigm involved the presentation of the same visual materials over three experiments alternating (experiment 1) negative and reference; (experiment 2) positive and reference and (experiment 3) positive and negative captioned pictures. The stimuli produced activation in both patients and comparison subjects in brain regions previously implicated in the generation and modulation of affect, in particular the prefrontal and anterior cingulate cortices. The activation in patients, when compared with healthy subjects, involved additional subcortical regions, in particular the amygdala, thalamus, hypothalamus and medial globus pallidus. Patients and comparison subjects displayed differential sensitivity to affective change with negative (experiment 1) and positive (experiment 2) affect induction producing converse patterns of activation. We conclude that bipolar depressed patients perhaps recruit additional subcortical limbic systems for emotional evaluation and this may reflect state-related or trait-related dysfunction. The differential patterns of activation inform us about bipolar depression and have potential diagnostic and therapeutic significance.

Adult↗

PubMed2004

Cognitive generation of affect in hypomania: an fMRI study.

OBJECTIVE: To identify the brain regions associated with the cognitive generation of affect in hypomanic bipolar patients. METHODS: The study examined 10 hypomanic female subjects with bipolar affective disorder, and 10 age- and sex-matched comparison subjects using functional magnetic resonance imaging (fMRI) while viewing alternating blocks of captioned-pictures designed to evoke negative, positive or no affective change. The activation paradigm involved the presentation of the same visual materials over three experiments alternating (a) negative and reference, (b) positive and reference and (c) positive and negative captioned-pictures. RESULTS: The stimuli produced activation in both patients and comparison subjects in brain regions previously implicated in the generation and modulation of affect, in particular the prefrontal cortex. Activation in patients involved additional subcortical regions namely the caudate and thalamus. CONCLUSIONS: This preliminary study suggests that hypomanic patients recruit additional subcortical limbic systems for emotional evaluation when advanced prefrontal cortical processing is no longer sufficient. The differential patterns of activation inform us about bipolar disorder and may have potential diagnostic and therapeutic significance.

Adult↗

PubMed2003

Hemispheric asymmetry and temporal profiles of cerebral pressure autoregulation in head injury.

A moving correlation index (Mx-ABP) between arterial blood pressure (ABP) and mean middle cerebral artery blood flow velocity (CBFV) can be used to monitor dynamic cerebrovascular autoregulation (CA) after traumatic brain injury (TBI). In this study we examined hemispheric CA asymmetry and temporal CA profiles, their relationship with ABP and CBFV, and their prognostic relevance. Mx-ABP was calculated for each hemisphere in 25 TBI patients second-daily for as long as they were receiving sedation and analgesia. Forty-nine recordings were obtained, between one and six per patient. Four time periods were defined: immediate--postinjury days (PID) 0 and 1; early--PID 2 and 3; intermediate--PID 4 and 5, and late--PID 6 and later. GOS was estimated at discharge, GOS 4 and 5 were considered favorable (15 patients) and GOS 1-3 unfavorable outcome (10 patients). A Mx difference >0.2 was classified as hemispheric asymmetry (HA). HA was observed at least once in 12 of the 25 patients (48%) and in 18 of 49 recordings (37%). It was observed during all time periods: 35%, 43%, 25%, 43%, respectively, and was not related to outcome. There was no difference in mean CBFV or ABP between patients with and without HA. HA was not related to interhemispheric CBFV differences. A significant improvement in Mx was seen over time. Hemispheric CA asymmetry is common after traumatic brain injury. It does not bear significant clinical or predictive relevance, and it is unrelated to CBFV or ABP. CA is most profoundly disturbed during the immediate postinjury phase and improves gradually during the ICU course. Further studies are needed to investigate CA during post ICU recovery and rehabilitation.

Adolescent↗

PubMed2003

Functional brain maps of Tower of London performance: a positron emission tomography and functional magnetic resonance imaging study.

Regional cerebral blood flow (rCBF) and blood oxygenation level-dependent (BOLD) contrasts represent different physiological measures of brain activation. The present study aimed to compare two functional brain imaging techniques (functional magnetic resonance imaging versus [(15)O] positron emission tomography) when using Tower of London (TOL) problems as the activation task. A categorical analysis (task versus baseline) revealed a significant BOLD increase bilaterally for the dorsolateral prefrontal and inferior parietal cortex and for the cerebellum. A parametric haemodynamic response model (or regression analysis) confirmed a task-difficulty-dependent increase of BOLD and rCBF for the cerebellum and the left dorsolateral prefrontal cortex. In line with previous studies, a task-difficulty-dependent increase of left-hemispheric rCBF was also detected for the premotor cortex, cingulate, precuneus, and globus pallidus. These results imply consistency across the two neuroimaging modalities, particularly for the assessment of prefrontal brain function when using a parametric TOL adaptation.

Adult↗

PubMed2003

Noninvasive cerebrovascular autoregulation assessment in traumatic brain injury: validation and utility.

A moving correlation index (Mx-CPP) of cerebral perfusion pressure (CPP) and mean middle cerebral artery blood flow velocity (CBFV) allows continuous monitoring of dynamic cerebral autoregulation (CA) in patients with severe traumatic brain injury (TBI). In this study we validated Mx-CPP for TBI, examined its prognostic relevance, and assessed its relationship with arterial blood pressure (ABP), CPP, intracranial pressure (ICP), and CBFV. We tested whether using ABP instead of CPP for Mx calculation (Mx-ABP) produces similar results. Mx was calculated for each hemisphere in 37 TBI patients during the first 5 days of treatment. All patients received sedation and analgesia. CPP and bilateral CBFV were recorded, and GOS was estimated at discharge. Both Mx indices were calculated from 10,000 data points sampled at 57.4Hz. Mx-CPP > 0.3 indicates impaired CA; in these patients CPP had a significant positive correlation with CBFV, confirming failure of CA, while in those with Mx < 0.3, CPP was not correlated with CBFV, indicating intact CA. These findings were confirmed for Mx-ABP. We found a significant correlation between impaired CA, indicated by Mx-CPP and Mx-ABP, and poor outcome for TBI patients. ABP, CPP, ICP, and CBFV were not correlated with CA but it must be noted that our average CPP was considerably higher than in other studies. This study confirms the validity of this index to demonstrate CA preservation or failure in TBI. This index is also valid if ABP is used instead of CPP, which eliminates the need for invasive ICP measurements for CA assessment. An unfavorable outcome is associated with early CA failure. Further studies using the Mx-ABP will reveal whether CA improves along with patients' clinical improvement.

Adolescent↗