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1.
J Clin Psychopharmacol ; 44(2): 133-140, 2024.
Article in English | MEDLINE | ID: mdl-38421922

ABSTRACT

PURPOSE/BACKGROUND: Anxiety symptoms in major depressive disorder (MDD) are frequent, and they decrease response to antidepressant treatment (ADT), and affect patient functioning. This post hoc analysis examined the efficacy of adjunctive brexpiprazole on individual depressive symptoms and functioning in patients with MDD with anxious distress. METHODS/PROCEDURES: Data were included from three 6-week, randomized, double-blind, placebo-controlled studies of adjunctive brexpiprazole in patients with MDD and inadequate response to ADTs (ClinicalTrials.gov identifiers: NCT01360645, NCT01360632, NCT02196506). Patients were stratified using proxy criteria for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, anxious distress. Changes in Montgomery-Åsberg Depression Rating Scale item scores and Sheehan Disability Scale mean score from baseline to week 6 were determined for ADT + brexpiprazole (2 and 2-3 mg) versus ADT + placebo. FINDINGS/RESULTS: At baseline, 450 of 746 patients (60.3%, 2 mg analysis) and 670 of 1162 patients (57.7%, 2-3 mg analysis) had anxious distress. In patients with anxious distress, ADT + brexpiprazole 2 mg or 2 to 3 mg showed greater improvements than ADT + placebo (P < 0.05) on the Montgomery-Åsberg Depression Rating Scale items of apparent sadness, reported sadness, inner tension, reduced sleep, reduced appetite, lassitude, inability to feel, and pessimistic thoughts (Cohen d effect sizes, 0.18-0.44), and on Sheehan Disability Scale mean score (effect sizes, 0.21-0.23). IMPLICATIONS/CONCLUSIONS: Adjunctive brexpiprazole is efficacious in reducing core depressive symptoms, sleep, and appetite, as well as improving functioning, in patients with MDD and anxious distress who have inadequate response to ADTs.


Subject(s)
Depressive Disorder, Major , Quinolones , Thiophenes , Humans , Antidepressive Agents , Anxiety/drug therapy , Depression , Depressive Disorder, Major/drug therapy , Double-Blind Method , Drug Therapy, Combination , Treatment Outcome , Randomized Controlled Trials as Topic
2.
J Psychiatr Res ; 162: 71-78, 2023 06.
Article in English | MEDLINE | ID: mdl-37099968

ABSTRACT

BACKGROUND: Patient-reported outcomes can capture domains that are meaningful to patients, such as life engagement in major depressive disorder (MDD), which reflects life fulfillment, well-being, and participation in valued and meaningful activities. This analysis investigated the effects of brexpiprazole adjunct to antidepressant treatment (ADT) on patient life engagement over the short and long term, using the 10-item Inventory of Depressive Symptomatology Self-Report (IDS-SR10) Life Engagement subscale. METHODS: Short-term data were pooled from three 6-week, randomized, double-blind studies of ADT + brexpiprazole 2-3 mg/day versus ADT + placebo in adult outpatients with MDD (DSM-IV-TR criteria) and inadequate response to ADTs. Long-term data were from a 26-52-week, open-label extension study of ADT + brexpiprazole 0.5-3 mg/day. RESULTS: Over 6 weeks, ADT + brexpiprazole (n = 579) showed greater improvement in IDS-SR10 Life Engagement subscale score than ADT + placebo (n = 583), with a least squares mean difference of -1.19 (95% confidence limits: -1.78, -0.59; p = 0.0001; Cohen's d effect size: 0.23). Greater improvement for ADT + brexpiprazole versus ADT + placebo (p < 0.05) was also observed on eight life engagement items, with effect sizes ranging from 0.12 to 0.24. In the long-term study, mean (standard deviation) IDS-SR10 Life Engagement subscale score changed by -2.4 (4.9) points to Week 26 (n = 2047), and -3.7 (5.3) points to Week 52 (n = 768), with mean improvements on all ten items. CONCLUSIONS: Beyond its efficacy on depressive symptoms, adjunctive brexpiprazole may improve patient life engagement, thereby helping patients with MDD to achieve personally meaningful functional outcomes.


Subject(s)
Depressive Disorder, Major , Adult , Humans , Depressive Disorder, Major/drug therapy , Self Report , Treatment Outcome , Drug Therapy, Combination , Antidepressive Agents/pharmacology , Double-Blind Method
3.
Adv Ther ; 39(11): 5259-5273, 2022 11.
Article in English | MEDLINE | ID: mdl-36136243

ABSTRACT

INTRODUCTION: To better inform clinicians about the use of etanercept biosimilar (SB4) in patients with rheumatoid arthritis (RA), COMPANION-B, a prospective real-world observational study, evaluated the effectiveness of the voluntary switch from originator (etanercept, ETN) to SB4 in patients with stable RA (low-disease activity/remission). METHODS: The study recruited adult patients (18 years or older) with RA (2010 American College of Rheumatology criteria) prescribed ETN as their first or second biologic for at least 6 months across 14 sites in Canada and five in Australia. Patients had stable disease (Disease Activity Score-28 using erythrocyte sedimentation rate [DAS28-ESR] less than 3.2) at enrollment with no evidence of flare within the previous 3 months. Concomitant disease-modifying antirheumatic drugs (DMARDs) were permitted. Patients could elect to continue ETN or voluntarily switch to SB4 in consultation with their doctors. The primary effectiveness measure was the proportion of patients with disease worsening (defined as a DAS28-ESR increase of at least 1.2 from baseline and minimum score of at least 3.2 or a defined modification in RA treatment) during 12 months of follow-up. The secondary effectiveness measure was the proportion of patients with disease worsening at month 6. Serious adverse events (SAEs) and non-serious adverse reactions (NSARs) were recorded. RESULTS: Of 163 patients enrolled, 109 elected to continue on ETN and 54 switched to SB4; 65.8% of patients received non-biologic DMARD(s), 52.6% methotrexate, and 10.5% oral corticosteroid(s). At month 12, the proportion of patients with disease worsening was comparable in the ETN group (22.8% [95% CI 15.0-32.2]) and SB4 group (17.6% [95% CI 8.4-30.9]). Similarly, the proportions of patients with disease worsening were also comparable at month 6 (ETN: 7.9% [95% CI 3.5-15.0]; SB4: 7.8% [95% CI 2.2-18.9]). SAEs were low and similar across both groups (ETN: 8.7%; SB4: 5.7%). NSARs were slightly higher in the SB4 vs. ETN group (13.2% vs. 2.9%). CONCLUSIONS: SB4 demonstrated comparable effectiveness to ETN over 12 months in patients with stable RA who voluntarily switched to the biosimilar in a real-world setting.


Subject(s)
Antirheumatic Agents , Arthritis, Rheumatoid , Biosimilar Pharmaceuticals , Adult , Arthritis, Rheumatoid/drug therapy , Etanercept , Humans , Methotrexate/therapeutic use , Prospective Studies , Treatment Outcome
4.
J Med Internet Res ; 21(6): e13360, 2019 06 28.
Article in English | MEDLINE | ID: mdl-31254339

ABSTRACT

BACKGROUND: In people with dementia, neuropsychiatric symptoms (NPSs), especially agitation, are associated with worse quality of life and caregiver burden. As NPSs may vary with illness severity, knowledge of how people with dementia and their caregivers describe and rate the importance of agitation symptoms can improve the understanding of the clinical meaningfulness of the manifestations of agitation. The internet provides new opportunities to better understand patient experiences, as patients and caregivers increasingly look to Web-based platforms as a means of managing symptoms. OBJECTIVE: The aim of this study was to examine Web-based reports from a dementia symptom website to better understand the symptoms of agitation and explore how they are being targeted for monitoring by caregivers of people with dementia. METHODS: The Dementia Guide website hosts a Web-based database used by caregivers (97%) and people with dementia (3%). From its 61 dementia symptoms, users can select relevant symptoms that they deem important to monitor or track the effects of treatment. We employed a staging algorithm to determine if individuals had mild cognitive impairment (MCI) or mild, moderate, or severe dementia. Agitation was defined using terms consistent with the International Psychogeriatrics Association's provisional consensus definition. We compared the proportion of people with NPSs and agitation across stages of dementia severity and studied how many agitation-defining descriptors were selected, and how often they occurred, by stage. RESULTS: As of March 2017, 4121 people had used the tracking tool, of whom 2577 provided sufficient data to allow disease severity staging. NPSs were tracked by 2127/2577 (82.54%) and agitation by 1898/2577 (73.65%). The proportion in whom agitation was tracked increased with increasing cognitive impairment: 68.5% (491/717) in people with MCI, and 72.50% (754/1040), 73.3% (378/516), and 90.5% (275/304) in mild, moderate, and severe dementia, respectively (χ23=54.9; P<.001). The number of NPS and agitation descriptors selected also increased with severity (median number of NPSs=1, 2, 2, and 3 for MCI, mild, moderate, and severe dementia, respectively, Kruskal-Wallis H Test H3=250.47; P<.001; median number of agitation descriptors=1, 2, 3, and 4, H3=146.11; P<.001). CONCLUSIONS: NPSs and agitation are common targets for tracking over the course of dementia and appear more frequently with increasing disease severity. These common and distressing symptoms represent clinically meaningful targets in treating people with dementia.


Subject(s)
Caregivers/psychology , Dementia/therapy , Psychomotor Agitation/therapy , Quality of Life/psychology , Adaptation, Psychological , Aged , Cross-Sectional Studies , Female , Humans , Internet , Male
5.
BMC Psychiatry ; 19(1): 114, 2019 04 16.
Article in English | MEDLINE | ID: mdl-30991969

ABSTRACT

BACKGROUND: With previously established efficacy of aripiprazole once-monthly injectable formulation (AOM) in pre-registration randomized controlled trials, the current study was designed to evaluate its effectiveness in patients treated for schizophrenia in regular clinical settings in Canada. METHODS: Following their clinicians' decision to prescribe AOM, 193 patients with a diagnosis of schizophrenia, were recruited from 17 Canadian community or hospital-based settings. The primary outcome of global functioning was assessed with the Global Assessment of Functioning Scale (GAF) at 3-month intervals for 1 year. Secondary outcomes (social and occupational functioning and illness severity) and adverse drug reactions (ADR) were also assessed. RESULTS: A majority of the 169 evaluable patients were within the first 5 years of diagnosis (early phase). A linear mixed model analysis showed a significant main effect of time (Type III test p < 0.001) after adjusting for baseline GAF score, with a change in mean GAF scores from 49 at baseline to 61 at 12 months. No differences between early vs late phase were observed. Results on secondary outcome measures of function (Social and Occupational Functioning Scale) and illness severity (Clinical Global Impression-Severity Scale and Brief Psychiatric Rating Scale) were similar. Serious ADRs were observed in 29 (14.6%) patients and akathisia in 18 (9.1%) patients. At month-12, significant (≥7%) weight gain was observed in 25.7% (n = 27/105) of patients. CONCLUSIONS: Treatment with AOM is effective in improving symptoms and functioning in schizophrenia patients treated in regular clinical settings. Akathisia was infrequent while one quarter of patients gained clinically significant weight. TRIAL REGISTRATION: Unique identifier: NCT02131415 . First posted: 06 May 2014.


Subject(s)
Antipsychotic Agents/administration & dosage , Aripiprazole/administration & dosage , Schizophrenia/drug therapy , Schizophrenia/epidemiology , Schizophrenic Psychology , Adolescent , Adult , Antipsychotic Agents/adverse effects , Aripiprazole/adverse effects , Brief Psychiatric Rating Scale , Canada/epidemiology , Cohort Studies , Drug Administration Schedule , Female , Follow-Up Studies , Humans , Male , Middle Aged , Prospective Studies , Schizophrenia/diagnosis , Treatment Outcome , Weight Gain/drug effects , Weight Gain/physiology , Young Adult
6.
J Clin Psychopharmacol ; 37(3): 347-350, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28383362

ABSTRACT

BACKGROUND: Long-acting injectable antipsychotics are treatment options for acute and long-term treatment of patients with schizophrenia. In a previously published 12-week randomized, double-blind, placebo-controlled clinical trial of patients with schizophrenia experiencing an acute psychotic episode, aripiprazole once-monthly 400 mg (AOM 400) produced significantly greater improvement than placebo on the primary endpoint, Positive and Negative Syndrome Scale (PANSS) total score at week 10. METHODS: To examine the efficacy of AOM 400 across a broader representation of schizophrenia symptoms, including agitation, a post hoc analysis of this trial was carried out to assess the change in PANSS Marder factor domains (positive symptoms, negative symptoms, disorganized thought, uncontrolled hostility/excitement, and anxiety/depression) and the PANSS excited component (equivalent to Marder factor domain uncontrolled hostility/excitement plus the tension item) by comparing differences in change from baseline between AOM 400 and placebo using a mixed model for repeated measures. RESULTS: The differences between treatment and placebo for all factors were statistically significant, with improvements seen as early as week 1 or 2, and maintained through week 12. Thus, AOM 400, supplemented with oral aripiprazole in the first 2 weeks, showed significantly greater efficacy versus placebo in acutely ill patients with schizophrenia in all 5 Marder illness domains, as well as in agitation as conceptualized by the PANSS excited component score. CONCLUSIONS: These findings indicate that AOM 400 is efficacious across the spectrum of schizophrenia symptoms in acutely ill patients, with implications for both short-term and, by extension, long-term patient outcomes.


Subject(s)
Antipsychotic Agents/administration & dosage , Antipsychotic Agents/pharmacology , Aripiprazole/administration & dosage , Aripiprazole/pharmacology , Outcome Assessment, Health Care , Psychotic Disorders/drug therapy , Schizophrenia/drug therapy , Acute Disease , Adult , Delayed-Action Preparations , Double-Blind Method , Humans
7.
J Affect Disord ; 156: 1-7, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24314926

ABSTRACT

BACKGROUND: Most adults with major depressive disorder (MDD) fail to achieve remission with index pharmacological treatment. Moreover, at least half will not achieve and sustain remission following multiple pharmacological approaches. Herein, we succinctly review treatment modalities proven effective in treatment-resistant depression (TRD). METHODS: We conducted a review of computerized databases (PubMed, Google Scholar) from 1980 to April 2013. Articles selected for review were based on author consensus, adequacy of sample size, the use of a standardized experimental procedure, validated assessment measures and overall manuscript quality. RESULTS: The evidence base supporting augmentation of conventional antidepressants with atypical antipsychotics (i.e., aripiprazole, quetiapine, and olanzapine) is the most extensive and rigorous of all pharmacological approaches in TRD. Emerging evidence supports the use of some psychostimulants (i.e., lisdexamfetamine) as well as aerobic exercise. In addition, treatments informed by pathogenetic disease models provide preliminary evidence for the efficacy of immune-inflammatory based therapies and metabolic interventions. Manual based psychotherapies remain a treatment option, with the most compelling evidence for cognitive behavioral therapy. Disparate neurostimulation strategies are also available for individuals insufficiently responsive to pharmacotherapy and/or psychosocial interventions. LIMITATIONS: Compared to non-treatment-resistant depression, TRD has been less studied. Most clinical studies on TRD have focused on pharmacotherapy-resistant depression, with relatively fewer studies evaluating "next choice" treatments in individuals who do not initially respond to psychosocial and/or neurostimulatory treatments. CONCLUSION: The pathoetiological heterogeneity of MDD/TRD invites the need for mechanistically dissimilar, and empirically validated, treatment approaches for TRD.


Subject(s)
Depressive Disorder, Major/therapy , Depressive Disorder, Treatment-Resistant/therapy , Adult , Algorithms , Depressive Disorder, Major/diagnosis , Depressive Disorder, Treatment-Resistant/diagnosis , Humans
8.
Retina ; 27(2): 216-21, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17290205

ABSTRACT

BACKGROUND: As part of a larger systematic review on the effect of omega-3 fatty acids on eye health, the aim of this report was to appraise and synthesize the evidence for the effects of omega-3 fatty acids in slowing down the progression of age-related macular degeneration (AMD) and/or decreasing the rate of progression to advanced forms of AMD. METHODS: A comprehensive search was undertaken in six databases (MEDLINE, PreMEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, CAB Health, and Dissertation Abstracts). RESULTS: Two unique studies, one randomized clinical trial (RCT) and one prospective cohort study, satisfied the eligibility criteria and were included in the review. The RCT reported evidence on the effect of omega-3 fatty acids in slowing down the progression of AMD. The prospective cohort study addressed the question: what is the evidence that omega-3 fatty acids decrease the rate of progression to advanced forms of AMD? CONCLUSIONS: Clinical research on this topic is scarce. Only two studies were eligible to be included in this review. Although one study result indicated efficacy of preventing AMD progression to its advanced form, this result needs to be duplicated and supported by future research.


Subject(s)
Fatty Acids, Omega-3/administration & dosage , Macular Degeneration/drug therapy , Databases, Factual , Disease Progression , Fatty Acids, Omega-3/therapeutic use , Humans , Randomized Controlled Trials as Topic
9.
Behav Brain Res ; 177(1): 90-9, 2007 Feb 12.
Article in English | MEDLINE | ID: mdl-17126922

ABSTRACT

Interferon-alpha (IFN-alpha) is used as a front-line treatment for cancer and other diseases. Reports of depression as a consequence of IFN-alpha therapy scatter the literature, generating interest in the CNS disruptions elicited by this cytokine. In the present work, we investigated the short- and long-term effects of a single systemic injection of vehicle, 10, or 1000 units of IFN-alpha on temperature, body weight, food intake, sickness behaviours, locomotor activity, and brain stimulation reward (BSR) thresholds elicited from the ventral tegmental area in female Long-Evans rats. Pioneered for studying motivational processes, BSR has been exploited as a tool for tracking hedonic status in animal models of depression. In this study, the main findings were that IFN-alpha did not induce anhedonia as defined by no increase in frequency thresholds. However, the analyses of sickness behaviours unveiled a significant increase in piloerection in all sham control animals that received an IFN-alpha injection while the BSR animal scores remained relatively unchanged between pre- and post-injection days. This pattern was also evident in the overall total sickness behaviour scores. Our data suggest that a single exposure to IFN-alpha treatment in female rats elicits long-term somatic effects, without altering hedonic status.


Subject(s)
Brain/drug effects , Immunologic Factors/pharmacology , Interferon-alpha/pharmacology , Reward , Animals , Behavior, Animal , Brain/physiology , Dose-Response Relationship, Radiation , Electric Stimulation/methods , Female , Motor Activity/drug effects , Motor Activity/physiology , Motor Activity/radiation effects , Rats , Rats, Long-Evans , Self Stimulation
10.
Can J Ophthalmol ; 41(4): 481-90, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16883366

ABSTRACT

BACKGROUND: Studies in preterm and term human infants have suggested that a dietary supply of omega-3 fatty acids is essential for optimal visual development. Several basic science studies support the hypothesis that omega-3 fatty acids may be useful therapeutic agents for pathologies of the retina and lens. As part of a systematic review of the effect of omega-3 fatty acids on eye health, the purpose of this study was to conduct a systematic review of the scientific-medical literature to appraise and synthesize the evidence for the effects of omega-3 fatty acids in preventing the development or progression of retinitis pigmentosa. METHODS: A comprehensive search was undertaken in MEDLINE, PREMEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Global Health, and Dissertation Abstracts. Unpublished literature was sought through manual searches of reference lists of included studies and key review articles and from the files of content experts. Searches were not restricted by language of publication, publication type, or study design. Eligibility criteria were applied to screen eligible studies on two levels. Data extraction and quality assessment were performed. RESULTS: Six studies published between 1995 and 2004 met eligibility criteria in investigating the question of the possible value of omega-3 fatty acids in slowing the progression of retinitis pigmentosa. Meta-analysis was not performed because there was not enough available information for formal quantitative analysis. INTERPRETATION: There are trends in improvement of some retinitis pigmentosa outcomes with omega-3 fatty acids in the higher quality studies. Clinical research is preliminary in this field, however. Accordingly, definitive answers will require significantly more observational and interventional clinical research.


Subject(s)
Fatty Acids, Omega-3/administration & dosage , Retinitis Pigmentosa/prevention & control , Databases, Factual , Diet , Disease Progression , Humans , Randomized Controlled Trials as Topic , Retinitis Pigmentosa/physiopathology , Treatment Outcome
11.
J Neuroimmunol ; 181(1-2): 19-28, 2006 Dec.
Article in English | MEDLINE | ID: mdl-16934876

ABSTRACT

Chronic omega-3 or omega-6 polyunsaturated fatty acid (n-3; n-6 respectively) treatment attenuated human interleukin-1beta (hIL-1beta; 5.0 microg/kg)-elicited rise of circulating ACTH levels and attenuated the sickness behavior and locomotor suppression elicited by the cytokine. Furthermore, hIL-1beta markedly elevated circulating levels of plasma IL-6, an effect attenuated by n-3, but not n-6 treatment. Such protective effects were not evident upon short-term (3 day) n-3 exposure. These results demonstrate that long-term administration of either n-3 or n-6 confers protection against several neuroendocrinological, immunological and behavioral actions of hIL-1beta challenge, although in general the effects of n-3 were more pronounced.


Subject(s)
Fatty Acids, Omega-3/pharmacology , Fatty Acids, Omega-6/pharmacology , Interleukin-1beta/pharmacology , Interleukin-6/blood , Neurosecretory Systems/drug effects , Adrenocorticotropic Hormone/blood , Animals , Behavior, Animal/drug effects , Body Temperature/drug effects , Corticosterone/blood , Fatty Acids/metabolism , Liver/metabolism , Male , Motor Activity/drug effects , Neuroimmunomodulation/drug effects , Rats , Rats, Sprague-Dawley
12.
Ophthalmology ; 113(7): 1165-72; quiz 1172-3, 1178, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16815401

ABSTRACT

TOPIC: What is the evidence for efficacy of dietary and/or supplemental omega-3 fatty acids in preventing age-related macular degeneration (AMD)? CLINICAL RELEVANCE: Age-related macular degeneraion is the leading cause of blindness and vision impairment in persons older than 50 years living in North America. There is no cure for AMD, and treatment does not usually restore vision but only prevents disease progression to a modest degree. omega-3 fatty acids are considered potentially important antioxidants and are being considered as an arm of the Age-Related Eye Disease Study II clinical trial. METHODS/LITERATURE REVIEWED: Keywords were searched in Medline, Pre-Medline, Embase, and the Cochrane Library on Ovid. There was no restriction on the year or language of publication. RESULTS: There were 6 observational studies found, but the specific outcomes, exposures, and covariates studied all varied greatly. CONCLUSION: There is some clinical evidence for protection of AMD from omega-3 fatty acids. However, the results are not consistent. Hence, our conclusion is that this issue is neither clearly supported nor refuted by the present world literature. This is an intriguing and extremely important question but needs further study first with prospective cohort designs and, if positive, randomized clinical trials.


Subject(s)
Fatty Acids, Omega-3/administration & dosage , Macular Degeneration/prevention & control , Antioxidants/administration & dosage , Diet , Dietary Supplements , Humans , Treatment Outcome
13.
Rev Neurosci ; 15(1): 47-74, 2004.
Article in English | MEDLINE | ID: mdl-15046199

ABSTRACT

Behavioral adaptations of double-pulse methods--primarily collision and refractory period tests--have been employed to unveil the electrophysiological and anatomical characteristics of neural networks of known function. These paradigms are based on trade-off functions: a determination of different combinations of stimuli that yield the same behavioral output. A detailed explanation of the logic and methodology underlying these techniques is elaborated in this paper. The implementation of such approaches to the study of brain stimulation reward (BSR) has provided a means of discriminating between the neurons underlying this behavior from other cells activated by the stimulating electrode, endowing them with a particularly powerful scientific scope. An increasingly detailed portrait of the BSR substrate, both within and outside the medial forebrain bundle, has been emerging as a result of these investigations and is reviewed in this paper. Finally, the challenges associated with these paradigms are discussed and potential solutions as well as future experimental ventures proposed. Attention is drawn to the major contribution of these methods to our understanding of the neural pathways and characteristics underlying BSR.


Subject(s)
Brain Mapping , Medial Forebrain Bundle/physiology , Reward , Self Stimulation/physiology , Adaptation, Physiological/physiology , Animals , Behavior, Animal , Electric Stimulation/methods , Medial Forebrain Bundle/anatomy & histology , Neural Conduction , Reaction Time , Refractory Period, Electrophysiological
14.
Brain Res ; 1003(1-2): 138-50, 2004 Apr 02.
Article in English | MEDLINE | ID: mdl-15019573

ABSTRACT

The amygdaloid complex is one of the structures thought to modulate brain stimulation reward (BSR) elicited from the median forebrain bundle (MFB). Previous metabolic and behavioral data from our laboratory point to the amygdaloid cortical nuclei as key to this process. In this study, thresholds for rewarding stimulation of the MFB were determined for 42 days, 21 days following an electrolytic lesion to amygdaloid nuclei ipsilateral to the stimulation electrode, and 21 days following one applied to the contralateral amygdala. A subset of animals showed post-lesion changes in MFB frequency thresholds that were maintained if not augmented after the second lesion. These ranged from 26% to 150% compared to baseline values, among the largest ever reported to our knowledge. Interestingly, damage to anterior sites within the cortical nuclei was the most effective in producing modifications to the rewarding value of the stimulation. Equally singular was the finding that contralateral lesions tended to alter thresholds more than ipsilateral ones, confirming our earlier finding of interhemispheric connectivity in amygdaloid modulation of MFB reward signals. This interpretation was substantiated by tracking long-term metabolic activity in the amygdala using cytochrome oxidase histochemistry. The density of reaction product at damaged amygdala sites was negatively correlated (r=-0.90) with the increases in thresholds obtained at contralateral MFB loci. Together with the fact that such large lesion effects are seldom obtained, our metabolic results point to the existence of a relationship between these nuclei and reward signals generated at the MFB. Moreover, our data suggest that this communication takes place interhemispherically.


Subject(s)
Amygdala/physiology , Cerebral Cortex/physiology , Medial Forebrain Bundle/physiology , Reward , Animals , Electric Stimulation/methods , Male , Rats , Rats, Long-Evans , Reaction Time/physiology
15.
Behav Neurosci ; 116(4): 660-71, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12148933

ABSTRACT

After electrolytic lesions to the cortical and adjacent amygdaloid subnuclei, thresholds for rewarding medial forebrain bundle (MFB) stimulation were tracked in 19 rats with bilateral implants and 8 with single implants. Results were categorized into 3 groups depending on the magnitude of the lesion effect on ipsilateral frequency thresholds: substantial (> 60%), small (> 26%), or none (< 26%), compared with baseline values. Five rats exhibited threshold increases up to 225%, among the largest reported to the authors' knowledge. Small shifts were observed in another 5 rats, and no change in the remaining 17 rats. Threshold changes in the contralateral electrode mirrored ipsilateral ones. Results suggest that specific amygdaloid subnuclei modulate MFB reward signals through a diffuse collateralized organization of fibers and lend support to the existence of interhemispheric links in MFB reward pathways.


Subject(s)
Amygdala/physiology , Cerebral Cortex/physiology , Prosencephalon/physiology , Reinforcement, Psychology , Amygdala/pathology , Animals , Cerebral Cortex/pathology , Electric Stimulation , Electrodes , Male , Rats
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