DIXDC1 contributes to psychiatric susceptibility by regulating dendritic spine and glutamatergic synapse density via GSK3 and Wnt/ß-catenin signaling.

Mice lacking DIX domain containing-1 (DIXDC1), an intracellular Wnt/ß-catenin signal pathway protein, have abnormal measures of anxiety, depression and social behavior. Pyramidal neurons in these animals' brains have reduced dendritic spines and glutamatergic synapses. Treatment with lithium or a glycogen synthase kinase-3 (GSK3) inhibitor corrects behavioral and neurodevelopmental phenotypes in these animals. Analysis of DIXDC1 in over 9000 cases of autism, bipolar disorder and schizophrenia reveals higher rates of rare inherited sequence-disrupting single-nucleotide variants (SNVs) in these individuals compared with psychiatrically unaffected controls. Many of these SNVs alter Wnt/ß-catenin signaling activity of the neurally predominant DIXDC1 isoform; a subset that hyperactivate this pathway cause dominant neurodevelopmental effects. We propose that rare missense SNVs in DIXDC1 contribute to psychiatric pathogenesis by reducing spine and glutamatergic synapse density downstream of GSK3 in the Wnt/ß-catenin pathway.

Doctor-Patient Communication in an Outpatient Setting

Aim To evaluate doctor patient communication within gynaecological oncology services in Ireland. Methods An anonymous and confidential 20 question survey was designed by the patient advocacy group ISGOPPI and distributed in three gynaecological oncology outpatient clinics in tertiary referral centres. Results A total of 84 patients completed the survey in the 3 Dublin hospitals. Doctors surveyed ranged from senior house officer to consultant level. Overall women were very satisfied with the communication they had received from their doctor. 85% felt that they the doctor listened to them and took their opinion into account. 84% of patients felt that the doctor's body language was appropriate throughout the consultation. One of the main issues for women surveyed was waiting times. 33% of women waited over an hour to see their doctor and over 30% of women did not receive contact details of the clinical nurse specialist. Conclusion Overall our study shows that patients in gynae-oncology clinics are satisfied with the communication from their doctors. The main issues for patients were waiting times and contact details for follow up questions.

Barriers to and enablers of insulin self-titration in adults with Type 2 diabetes: a qualitative study.

AIMS: To identify the barriers to and enablers of effective insulin self-titration in people with Type 2 diabetes. METHODS: A qualitative semi-structured interview approach was used. Questions were structured according to the Theoretical Domains Framework, which outlines 14 domains that can act as barriers to and enablers of changing behaviour. Interviews were audio-recorded and transcribed verbatim. The data were coded according to the 14 domains, belief statements were created within each domain, and a frequency count of the most reported barriers and enablers was then carried out. Analyses were conducted by two researchers, and discrepancies agreed with a third researcher. RESULTS: A total of 18 adults with Type 2 diabetes took part in an interview. The majority were of South-Asian ethnicity (n = 8) and were men (n = 12). Their mean age was 61 years old. The mean duration of diabetes was 16 years and time on insulin 9 years. Inter-rater reliability for each of the domains varied (29-100%). The most frequently reported domains were Social Influence and Beliefs about Consequences; the least frequently reported were Optimism and Reinforcement. Interviewees reported receiving support to self-titrate from a range of sources. Self-titrating was perceived to have a range of both positive and negative consequences, as was not titrating. CONCLUSIONS: The findings highlight that those interviewed experienced a range of barriers and enablers when attempting to self-titrate. Improved education and training when initiating insulin treatment among adults with Type 2 diabetes, and throughout their journey on insulin therapy could help identify and address these barriers in order to optimize self-titration.

Attitudes of women with gestational diabetes toward diet and exercise: a qualitative study.

OBJECTIVE: Gestational diabetes (GDM) refers to glucose intolerance of varying severity first occurring in pregnancy. Following a diagnosis of GDM, exercise and dietary modification has a positive effect on improving glycemic control. Lifestyle changes affected in pregnancies affected by GDM have beneficial effects on long-term health if continued following birth. In addition, the psychological impact of a diagnosis of GDM should not be overlooked. Reports of maternal stress, anxiety, and fear are commonly reported issues in the literature. Support, both socially and from health care professionals, is also linked with higher rates of success in GDM management. Research to date had focused on women's reaction to a diagnosis of GDM, their mood and quality of life following a diagnosis, and their knowledge or opinions on the management of GDM. This qualitative study explored the attitudes of women with GDM toward these lifestyle changes, specifically diet and exercise. Women were also asked to identify advice that would be useful for other women newly diagnosed with GDM. METHODS: With ethical approval a qualitative study was conducted using semi-structured interviews which were examined using Thematic Analysis. Patients were invited to participate and gave written consent after a discussion with a study researcher. The question plan for semi-structured interviews was designed with the advice of patient advocates. Recurrent themes were developed until the saturation of data. RESULTS: Thirty-two women took part in the study. Time, convenience, and lack of educational awareness were common barriers to healthy eating and physical activity plans. Enablers for change included meal planning and organization. Women regarded their diets pre-diagnosis as healthy, with small "tweaks" (such as portion control) required to comply with recommendations. Another significant facilitator to change was support from the woman's partner. This also set a benchmark for plans of diet maintenance within the family structure after pregnancy. Unlike dietary changes, a consistent theme was that exercise was considered a "chore" in managing GDM and was unlikely to be continued in the long term. Practical advice offered by participants for other women with GDM included organization, realistic approaches, and lack of self-blame. CONCLUSION: Women reported that changes in diet would be more achievable in the long term than changes in exercise patterns. Partners and the clinical team were significant sources of support. Women's views are crucial to providing clinicians with a comprehensive and holistic understanding of disease management. Involving women in self-care decisions and empowering women to manage their own health are key contributors to long-term behavior change as well as service provision and policy implementation.

Psycho-educational interventions designed to prevent deployment-related psychological ill-health in Armed Forces personnel: a review.

BACKGROUND: Employers such as the Armed Forces (AF) and emergency services, who predictably expose their staff to potentially traumatic events (PTEs), often provide psycho-educational briefings in an attempt to mitigate possible adverse psychological sequelae. Within the military, psycho-educational briefings are widely used, particularly following exposure to PTEs on operations. The aim of this review was to evaluate the efficacy of these interventions and make appropriate recommendations. METHOD: A search of Medline, PsycINFO and EMBASE was conducted, bibliographies of retrieved articles were searched and experts in the field were consulted. RESULTS: Two surveys and seven intervention studies were identified for inclusion in the review. Only three studies were randomized controlled trials (RCTs). Overall, the review found some evidence of benefit of psycho-educational interventions but it was not consistent across studies or outcomes and effects were small. However, there was also little evidence to suggest that they caused harm. There was some evidence that the beneficial effects may be greater for those who have been exposed to a higher number of PTEs. CONCLUSIONS: Given the high operational tempo currently faced by coalition forces personnel, there remains a pressing need to identify the most effective way of minimizing the impact of exposure to potentially traumatic deployment incidents. To date, few psycho-educational interventions designed to prevent deployment-related psychological ill-health have been evaluated systematically in methodologically robust studies. The review recommends that future interventions are theoretically based and evaluated in cluster RCTs that examine both process and outcome variables.

Exposure to bisphenol A differentially impacts neurodevelopment and behavior in Drosophila melanogaster from distinct genetic backgrounds.

Bisphenol A (BPA) is a ubiquitous environmental chemical that has been linked to behavioral differences in children and shown to impact critical neurodevelopmental processes in animal models. Though data is emerging, we still have an incomplete picture of how BPA disrupts neurodevelopment; in particular, how its impacts may vary across different genetic backgrounds. Given the genetic tractability of Drosophila melanogaster, they present a valuable model to address this question. Fruit flies are increasingly being used for assessment of neurotoxicants because of their relatively simple brain structure and variety of measurable behaviors. Here we investigated the neurodevelopmental impacts of BPA across two genetic strains of Drosophila-w1118 (control) and the Fragile X Syndrome (FXS) model-by examining both behavioral and neuronal phenotypes. We show that BPA induces hyperactivity in larvae, increases repetitive grooming behavior in adults, reduces courtship behavior, impairs axon guidance in the mushroom body, and disrupts neural stem cell development in the w1118 genetic strain. Remarkably, for every behavioral and neuronal phenotype examined, the impact of BPA in FXS flies was either insignificant or contrasted with the phenotypes observed in the w1118 strain. This data indicates that the neurodevelopmental impacts of BPA can vary widely depending on genetic background and suggests BPA may elicit a gene-environment interaction with Drosophila fragile X mental retardation 1 (dFmr1)-the ortholog of human FMR1, which causes Fragile X Syndrome and is associated with autism spectrum disorder.

Cortactin underpins CD44-promoted invasion and adhesion of breast cancer cells to bone marrow endothelial cells.

Using a validated tetracycline (tet)-regulated MCF7-founder (MCF7F) expression system to modulate expression of CD44 standard form (CD44s), we report the functional importance of CD44s and that of a novel transcriptional target of hyaluronan (HA)/CD44s signaling, EMS1/cortactin, in underpinning breast cancer metastasis. In functional experiments, tet-regulated induction of CD44s potentiated the migration and invasion of MCF7F cells through HA-supplemented Matrigel. EMS1/cortactin was identified by expression profiling as a novel transcriptional target of HA/CD44 signaling, an association validated by quantitative PCR and immunoblotting experiments in a range of breast cancer cell lines. The mechanistic basis underpinning CD44-promoted transcription of EMS1/cortactin was shown to be dependent upon a NFkappaB mechanism, since pharmacological inhibition of IkappaKinase-2 or suppression of p65 Rel A expression attenuated CD44-induced increases in cortactin mRNA transcript levels. Overexpression of a c-myc tagged murine cortactin construct in the weakly invasive, CD44-deficient MCF7F and T47D cells potentiated their invasion. Furthermore, the functional importance of cortactin to CD44s-promoted metastasis was demonstrated by selective suppression of cortactin in CD44-expressing MCF7F-B5 and MDA-MB-231 breast cancer cells using RNAi, which was shown to result in attenuated CD44-promoted invasion and CD44-promoted adhesion to bone marrow endothelial cells (BMECs).

Measurement of de novo hepatic lipogenesis in humans using stable isotopes.

Direct measurement of de novo lipogenesis has not previously been possible in humans. We measured de novo hepatic lipogenesis in normal men by means of stable isotopes and by combining the acetylated-xenobiotic probe technique with mass isotopomer analysis of secreted very low density lipoprotein-fatty acids (VLDL-FA). Sulfamethoxazole (SMX) was administered with [13C]acetate during an overnight fast followed by refeeding with intravenous glucose (7-10 mg/kg of weight per min), oral Ensure (7-10 mg of carbohydrate/kg of weight per min), or a high-carbohydrate mixed-meal breakfast (3.5 g of carbohydrate/kg of weight). Respiratory quotients remained less than 1.0. High-performance liquid chromatography/mass spectrometry-determined enrichments in SMX-acetate attained stable plateau values, and hepatic acetyl-coenzyme A (CoA) dilution rate did not increase with refeeding (approximately 0.024 mmol/kg per min). The fraction of VLDL-palmitate derived from de novo lipogenesis was only 0.91 +/- 0.27% (fasted) and 1.64-1.97% (fed). For stearate, this was 0.37 +/- 0.08% and 0.47-0.64%. Precursor enrichments predicted from isotopomer ratios were close to measured SMX-acetate enrichments, indicating that SMX-acetate samples the true lipogenic acetyl-CoA pool. Stearate synthesis was less than palmitate and the two did not move in parallel. Estimated total VLDL-FA synthesis is less than 500 mg/day. Thus, de novo hepatic lipogenesis is a quantitatively minor pathway, consistent with gas exchange estimates; fatty acid futile cycling (oxidation/resynthesis) is not thermogenically significant; and synthesis rates of different nonessential fatty acids by human liver are not identical in nonoverfed normal men. The contribution and regulation of de novo lipogenesis in other settings can be studied using this technique.

Current concepts in the diagnosis and management of metabolic complications of HIV infection and its therapy.

Changes in fat distribution, dyslipidemia, disordered glucose metabolism, and lactic acidosis have emerged as significant challenges to the treatment of human immunodeficiency virus (HIV) infection. Over the past decade, numerous investigations have been conducted to better define these conditions, identify risk factors associated with their development, and test potential therapeutic interventions. The lack of standardized diagnostic criteria, as well as disparate study populations and research methods, have led to conflicting data regarding the diagnosis and treatment of metabolic and body shape disorders associated with HIV infection. On the basis of a review of the medical literature published and/or data presented before April 2006, we have prepared a guide to assist the clinician in the detection and management of these complications.

Metabolic effects of indinavir in healthy HIV-seronegative men.

BACKGROUND: Therapy with HIV protease inhibitors (PI) has been associated with hyperglycemia, hyperlipidemia and changes in body composition. It is unclear whether these adverse effects are drug related, involve an interaction with the host response to HIV or reflect changes in body composition. METHODS: Indinavir 800 mg twice daily was given to 10 HIV-seronegative healthy men to distinguish direct metabolic effects of a PI from those related to HIV infection. Fasting glucose and insulin, lipid and lipoprotein profiles, oral glucose tolerance (OGTT), insulin sensitivity by hyperinsulinemic euglycemic clamp, and body composition were measured prior to and after 4 weeks of indinavir therapy. RESULTS: Fasting glucose (4.9 +/- 0.1 versus 5.2 +/- 0.2 mmol/l; P = 0.05) insulin concentrations (61.7 +/- 12.2 versus 83.9 +/- 12.2 pmol/l; P < 0.05), insulin : glucose ratio (12.6 +/- 1.7 versus 15.9 +/- 1.9 pmol/mmol; P < 0.05) and insulin resistance index by homeostasis model assessment (1.9 +/- 0.3 versus 2.8 +/- 0.5;P < 0.05) all increased significantly. During OGTT, 2 h glucose (5.1 +/- 0.4 versus 6.5 +/- 0.6 mmol/l; P < 0.05) and insulin levels (223.1 +/- 48.8 versus 390.3 +/- 108.8 pmol/l;P =0.05) also increased significantly. Insulin-mediated glucose disposal decreased significantly (10.4 +/- 1.4 versus 8.6 +/- 1.2 mg/kg x min per microU/ml insulin; 95% confidence interval 0.6--.0;P < 0.01). There was no significant change in lipoprotein, triglycerides or free fatty acid levels. There was a small loss of total body fat (15.8 +/- 1.4 versus 15.2 +/- 1.4 kg;P = 0.01) by X-ray absorptiometry without significant changes in weight, waist : hip ratio, and visceral or subcutaneous adipose tissue by computed tomography. CONCLUSIONS: In the absence of HIV infection, treatment with indinavir for 4 weeks causes insulin resistance independent of increases in visceral adipose tissue or lipid and lipoprotein levels.

Changes in weight and lean body mass during highly active antiretroviral therapy.

BACKGROUND: Few studies have prospectively evaluated the impact of highly active antiretroviral therapy (HAART) on body weight and lean body mass (LBM) or explored the impact of baseline immunologic or virological changes on these parameters. METHODS: Adult AIDS Clinical Trials Group (ACTG) protocol 892 was a prospective, 48-week, multisite observational study of body composition conducted during 1997-2000 among 224 antiretroviral-naive and antiretroviral-experienced subjects coenrolled into various adult ACTG antiretroviral studies. Assessments included human immunodeficiency virus type 1 (HIV-1) RNA load (by polymerase chain reaction); T lymphocyte subset analysis; Karnofsky score; height (baseline only); weight, LBM, and fat (by bioelectrical impedance analysis); and functional performance (by questionnaire). RESULTS: Overall, only modest median increases in body weight (1.9 kg) and LBM (0.6 kg) occurred after 16 weeks of therapy. Significantly greater median increases in body weight (2.1 vs. 0.5 kg; P=.045) occurred in subjects who achieved virological suppression (HIV-1 RNA load, <500 copies/mL) at week 16 than in subjects who did not. Subjects who were antiretroviral naive at baseline gained more weight (median increase in body weight, 2.6 vs. 0.0 kg; P<.001) and LBM (1.0 vs. 0.1 kg; P=.002) after 16 weeks of treatment than did subjects who were antiretroviral experienced. Subjects with lower baseline CD4 cell counts (<200 cells/mm3) and subjects with higher baseline HIV-1 RNA loads (> or =100,000 copies/mL) were more likely to show increases in LBM of >1.5 kg (P=.013 and P=.005, respectively). CONCLUSIONS: HAART had modestly favorable effects on body composition, particularly in patients with greater pretreatment immunocompromise and virological compromise. The difference between antiretroviral-naive and antiretroviral-experienced subjects with regard to the ability to achieve increased body weight and LBM requires more study.

Effects of chronic growth hormone treatment on energy intake and resting energy metabolism in patients with human immunodeficiency virus-associated wasting--a clinical research center study.

In previous studies, treatment with recombinant human GH (rhGH) produced sustained increases in weight and lean body mass (LBM) and decreases in fat mass in patients with human immunodeficiency virus (HIV)-associated wasting. To evaluate the effects of chronic rhGH treatment on components of energy balance, we recruited separate subgroups of HIV-positive patients with an involuntary weight loss of 10% or more to undergo paired measurements of resting energy metabolism (n = 6) or food intake (n = 11) before and during the final week of a 3-month rhGH (0.1 mg/kg.day) treatment period. In the energy metabolism subset, resting energy expenditure (REE) and substrate oxidation rates were measured by indirect calorimetry during brief admissions to a metabolic ward. Patients in the energy intake subset prepared written 4-day food intake diaries. Body composition was measured in both groups by bioelectrical impedance analysis. Changes in weight (+2.2 +/- 0.9 and +2.2 +/- 0.6 kg), LBM (+3.2 +/- 0.6 and +3.8 +/- 0.5 kg), and fat (-1.0 +/- 0.5 and -1.6 +/- 0.5 kg) in the energy metabolism and energy intake subsets, respectively, did not differ between groups and were comparable to changes seen in a larger group of patients who received rhGH in a randomized, double blind, placebo-controlled multicenter study. In the energy metabolism subset, REE (+232 +/- 69 Cal/day; P = 0.020) and lipid oxidation (+3.1 +/- 1.0 Cal/kg LBM.day; P = 0.016) increased, whereas protein oxidation decreased (-1.3 +/- 1.0 Cal/kg LBM.day; P = 0.027) during rhGH therapy. These changes in REE and substrate oxidation are comparable to changes we noted previously in a study of the effects of short term rhGH treatment in patients with HIV-associated wasting. Moreover, the sustained increases in lipid oxidation are consistent with the decreases in body fat content that occur with rhGH treatment. In the energy intake subset, a trend for increased daily energy intake (+203 +/- 262 Cal; P = 0.456) is obviated when adjustments for changes in weight or LBM are made (+1.3 +/- 4.0 and -0.5 +/- 5.0 Cal/kg BW and LBM, respectively). Taken together, these results demonstrate that increases in weight and LBM that occur with chronic rhGH therapy are accompanied by sustained increases in REE and lipid oxidation and decreases in protein oxidation. These changes in body composition occur without a significant increase in energy intake and may, instead, represent a redistribution of body energy stores.

Anabolic effects of recombinant human growth hormone in patients with wasting associated with human immunodeficiency virus infection.

Body wasting, characterized by disproportionate loss of body cell mass, is a feature of many chronic diseases, including infection with the human immunodeficiency virus (HIV). Therapies that merely increase energy intake do not consistently restore body cell mass in patients with the wasting syndrome. Because treatment with GH has induced nitrogen (N) retention in catabolic patients after surgery, burns, cancer, and hypocaloric feeding, we designed this study to determine whether GH could also produce an anabolic response in persons with HIV-associated weight loss. Six HIV-positive (HIV+) men with an average weight loss of 19% and six healthy weight-stable controls (HIV-) were hospitalized on a metabolic ward, where they consumed a constant metabolic diet during successive 5-day precontrol, 7-day baseline, and 7-day treatment [recombinant human GH (rhGH), 0.1 mg/kg.day] periods. The effects of rhGH on body weight, N and electrolyte excretion, energy expenditure, substrate oxidation, and integrated lipid and carbohydrate metabolism were assessed. Body weight increased promptly and progressively during treatment (2.0 +/- 0.3 and 1.6 +/- 0.2 kg in HIV+ and HIV-, respectively). Urinary N excretion decreased by 288 +/- 17 and 287 +/- 42 mmol/day in HIV+ and HIV-, respectively. Resting energy expenditure increased by 7.5% in both groups. Protein oxidation decreased, whereas lipid oxidation increased significantly. Glucose flux increased, and modest increases in fasting plasma triglyceride, glucose, and insulin levels were observed. Thus, short term rhGH treatment increased both protein anabolism and protein-sparing lipid oxidation, effects that should increase body cell mass if sustained during chronic therapy.

The effects of recombinant human growth hormone on body composition and glucose metabolism in HIV-infected patients with fat accumulation.

GH has been proposed as a therapy for patients with HIV-associated fat accumulation, but the pharmacological doses (6 mg/d) used have been associated with impaired fasting glucose and hyperglycemia. In contrast, physiologic doses of GH ( approximately 1 mg/d) in HIV-negative men reduced visceral adiposity and eventually improved insulin sensitivity, despite initially causing insulin resistance. We conducted an open-label study to evaluate the effects of a lower pharmacologic dose of GH (3 mg/d) in eight men with HIV-associated fat accumulation. Oral glucose tolerance, insulin sensitivity, and body composition were measured at baseline, and 1 and 6 months. Six patients completed 1 month and 5, 6 months of GH therapy. IGF-I levels increased 4-fold within 1 month of GH treatment. Over 6 months, GH reduced buffalo hump size and excess visceral adipose tissue. Total body fat decreased (17.9 +/- 10.9 to 13.5 +/- 8.4 kg, P = 0.05), primarily in the trunk region. Lean body mass increased (62.9 +/- 6.4 to 68.3 +/- 9.1 kg, P = 0.03). Insulin-mediated glucose disposal, measured by a euglycemic hyperinsulinemic clamp, declined at month 1 (49.7 +/- 27.5 to 25.6 +/- 6.6 nmol/kg(LBM).min/pmol(INSULIN)/liter, P = 0.04); values improved at month 6 (49.2 +/- 22.6, P = 0.03, compared with month 1) and did not differ significantly from baseline. Similarly, the integrated response to an oral glucose load worsened at month 1 (glucose area under the curve 20.1 +/- 2.3 to 24.6 +/- 3.7 mmol.h/liter, P < 0.01), whereas values improved at month 6 (22.1 +/- 1.5, P = 0.02, compared with month 1) and did not differ significantly from baseline. One patient developed symptomatic hyperglycemia within 2 wk of GH initiation; baseline oral glucose tolerance testing revealed preexisting diabetes despite normal fasting glucose. In conclusion, GH at 3 mg/d resulted in a decrease in total body fat and an increase in lean body mass in this open-label trial. While insulin sensitivity and glucose tolerance initially worsened, they subsequently improved toward baseline. However, the dose of GH used in this trial was supraphysiologic and led to an increase in IGF-I levels up to three times the upper normal range. Because there are known adverse effects of long-term GH excess, the effectiveness of lower doses of GH should be studied. We also recommend a screening oral glucose tolerance test be performed to exclude subjects at risk for GH-induced hyperglycemia.

Serotoninergic innervation of the cat cerebral cortex.

Serotoninergic axons in the cat cerebral cortex were demonstrated immunohistochemically with a monoclonal antibody to serotonin (5-HT). Three types of 5-HT axons are distinguished at the light microscopic level by differences in their morphology. Small varicose axons are fine (less than 0.5 micron) and bear fusiform varicosities that are generally less than 1 micron in diameter. These axons extend throughout the width of the cortex and branch frequently, giving rise to widely spreading collaterals. Nonvaricose axons are smooth, show a relatively large and constant caliber (about 1 micron), travel in straight, horizontal trajectories, and branch infrequently. Large varicose axons are distinguished by large round or oval varicosities (1 micron or more in diameter) borne on fine-caliber fibers. These axons often form basket-like arbors around the somata of single neurons. In the simplest basket-like arbors, several large, round varicosities from a small number of axons contact the soma. In complex baskets intertwining collaterals contact the soma and apparently climb along and outline the cell's major dendrites. The patterns revealed by the climbing axons suggest that a variety of nonpyramidal cell types selectively receive dense 5-HT innervation. Serial reconstructions of the 5-HT axons within the cortex show that the large varicose axons arise as infrequent collaterals from the nonvaricose axons. A single nonvaricose parent axon gives rise to several large varicose axon collaterals that may contribute to different basket-like arbors. Conversely, a single basket-like arbor may be formed by large varicose axon collaterals from more than one nonvaricose parent axon. The small varicose axons do not appear to be related within the cortex to either the nonvaricose or large varicose axon types. The results support the hypothesis that the 5-HT projection to the cortex is organized into two subsystems, one of which may exert widespread influence in the cortex via highly divergent branches, while the other, with a more restricted distribution, acts on specific classes of cortical neurons.

Organization of geniculocortical projections in turtles: isoazimuth lamellae in the visual cortex.

The projection from the dorsal lateral geniculate complex to the visual cortex in Pseudemys and Chrysemys turtles was examined by using the anterograde transport of horseradish peroxidase (HRP) in vitro and the retrograde transport of HRP in vivo. In vitro HRP injections into the lateral forebrain bundle were used to fill geniculocortical axons anterogradely, which were then analyzed in cortical wholemount preparations. Geniculocortical axons gain access to the visual cortex along its entire rostral-caudal extent. They course in slightly curved trajectories for up to 2 mm from the lateral edge of the cortex through both the lateral (or pallial thickening) and medial parts of Desan's cortical area D2. Single axons are of fine caliber. They tend to cross each other and sometimes branch in the pallial thickening, but are generally unbranched in the medial part of D2. They bear small, fusiform varicosities at irregular intervals along their lengths. Although axons show small variations in the number of varicosities per 100 microns segment, no consistent variation in varicosity number as a function of distance could be detected. These results indicate that geniculocortical axons project to the visual cortex in an orderly pattern. The retrograde transport experiments provide some clue as to the significance of this pattern. Small, ionotophoretic injections of HRP in the visual cortex retrogradely labeled neurons in the dorsal lateral geniculate complex. Injections in the rostral visual cortex retrogradely labeled neurons in the caudal pole of the geniculate complex. Injections at progressively more caudal loci within the visual cortex labeled neurons at progressively more rostral loci within the geniculate complex. Thus, there is a representation of the rostral-caudal axis of the geniculate complex along the caudal-rostral axis of the visual cortex. Consistent with the anterograde transport experiments that showed individual geniculocortical axons coursing through both lateral and medial parts of the visual cortex, HRP injections restricted to the medial edge of the visual cortex retrogradely labeled neurons along the entire dorsal-ventral axis of the geniculate complex at the appropriate rostral-caudal position. The neurophysiological studies of Mazurskaya ('72: J. Evol. Biochem. Physiol. 8:550-555; respond to a small, moving stimulus anywhere in visual space, implying a convergence of inputs from all points in visual space somewhere along the retinogeniculocortical pathway. The experiments reported here suggest a convergence in the geniculocortical projections of information along the vertical meridians, or azimuth lines, of visual space onto neurons lying along lateral to medial transects through the visual cortex.(ABSTRACT TRUNCATED AT 400 WORDS)