Functional interaction between the basolateral amygdala and the nucleus accumbens underlies incentive motivation for food reward on a fixed ratio schedule.

The ability for incentive properties of reward stimuli to maintain motivated behavior in the absence of the rewards themselves may be reliant in part on a glutamatergic projection from the basolateral (BLA) amygdala to the nucleus accumbens septi (NAS). The present work examined this idea in regard to food reward. In the first part of this study, lever pressing by rats on a fixed ratio 16 (FR16) schedule of food reinforcement was suppressed in a dose-dependent manner following bilateral infusion of the GABA(A) agonist muscimol to the BLA. Consumption of food when freely available was unaffected by the highest dose of muscimol, suggesting no change in the primary reward value of the food. Bilateral infusion of the broad-spectrum dopamine (DA) receptor antagonist flupenthixol to the NAS also resulted in a significant decrease in FR16 performance. As with the amygdala, consumption of freely available food was not affected by flupenthixol injections into the NAS. When unilateral injection of flupenthixol to the NAS was combined with contralateral injection of muscimol to the BLA, FR16 performance was suppressed. No significant change in lever press performance was observed following unilateral NAS injection of flupenthixol combined with ipsilateral injection of muscimol to the BLA. The results of this study support the idea that a functional connection between the BLA and NAS transmits incentive information necessary for the maintenance of responding in the absence of primary reward.

Arthroscopically assisted reconstruction of the anterior cruciate ligament. A follow-up report.

BACKGROUND: The purpose of this study was to further delineate the outcome of arthroscopically assisted anterior cruciate ligament reconstruction in 125 patients who had previously been followed for two to five years. One of the original 125 patients was excluded from the present study because of insufficient follow-up, and an additional group of 101 patients was added. All 225 patients in the present study were followed for a minimum of six years. METHODS: Patients were randomly assigned to reconstruction with a double-stranded semitendinosus-gracilis graft with use of a two-incision technique (group I), reconstruction with a patellar ligament graft with use of a two-incision technique (group II), or reconstruction with a patellar ligament graft with use of a single-incision endoscopic technique (group III). The groups were compared with regard to the rate of graft failure, the amount of instability, knee strength, radiographic signs of degenerative changes, and functional outcome. RESULTS: There was no significant difference among the three groups with regard to the rate of graft failure, the amount of knee instability, or the functional outcome. A normal or nearly normal functional outcome was recorded for 208 (92%) of the 225 patients. There were significant differences among the groups with regard to quadriceps muscle-strength deficits: group I had fewer patients with deficits than group III, and groups I and III both had fewer patients with deficits than group II (p = 0.04). There also were significant differences among the groups with regard to hamstring muscle-strength deficits: group III had fewer patients with deficits than group II, and group II had fewer patients with deficits than group I (p < 0.01). Twelve knees (16%) in group I, six knees (8%) in group II, and eight knees (11%) in group III showed radiographic evidence of progressive degenerative changes, but the differences among the three groups were not significant. CONCLUSION: Although 11.6% of the 225 knees had radiographic evidence of degenerative arthritis at a minimum of six years after arthroscopically assisted reconstruction of the anterior cruciate ligament, the choice of graft and the technique of reconstruction did not seem to affect the rate of development of these changes.

Optimality under noise: higher memory strategies for the alternating prisoner's dilemma.

The Alternating Prisoner's Dilemma is a variant of the iterated Prisoner's Dilemma in which the players alternate in the roles of actor and recipient. We searched for strategies which are "optimal" in the Alternating Prisoner's Dilemma with noise (a non-zero probability that a player's decision will be transmitted incorrectly). In order to achieve success against a variety of other strategies, a strategy must be "self-cooperating" (able to achieve mutual cooperation with its clone), "C-exploiting" (able to exploit unconditional cooperators), and "D-unexploitable" (able to resist exploitation by defectors). It must also have high evolutionary "dominance", a general measure of evolutionary performance which considers both resistance to invasion and the ability to invade other strategies. A strategy which meets these optimality criteria can evolve cooperation by invading a population of defectors and establishing a stable cooperative society. Most of the strategies commonly discussed in the Alternating Prisoner's Dilemma literature are low-memory strategies such as Tit For Tat, Pavlov, and Firm But Fair, but none of these strategies can simultaneously meet all of the optimality criteria. However, we discovered a class of higher memory "Firm Pavlov" strategies, which not only meet our stringent optimality criteria, but also achieve remarkable success in round-robin tournaments and evolutionary interactions. These higher memory strategies are friendly enough to cooperate with their clone, pragmatic enough to exploit unconditional cooperators, and wary enough to resist exploitation by defectors: they are truly "optimal under noise" in the Alternating Prisoner's Dilemma.

Treatment for clinical malaria is sought promptly during an epidemic in a highland region of Uganda.

Early diagnosis of malaria followed by appropriate treatment can help reduce related morbidity and mortality as well as interrupt transmission. Previous studies of household responses to malaria have tended to focus on endemic areas where the burden of this disease is greatest. With the apparent increasing frequency of epidemics in African highlands, a better understanding of treatment behaviours in areas of unstable transmission may be important to future public health interventions. This study was undertaken following a serious epidemic of malaria in the highlands of south-western Uganda. Our objectives were to characterize actions taken by both adults and caretakers of children < or =5 years old during their most recent episode of self-diagnosed malaria, and to identify factors that were associated with prompt treatment at a health facility. A survey of 300 households selected in a 2-stage cluster sampling procedure produced 453 adult respondents and 133 caretakers of children < or =5 years old. We found that almost 65% of adults and 62% of children who had experienced an episode of malaria in the last year (most during the epidemic) had sought treatment from a health facility first as opposed to self-treatment. Most of these people had visited the health facility within 1 day of symptom onset. By the end of their malaria episode, over 87% of adults and 80% of children had visited a health facility at least once. Factors associated with prompt presentation at a health facility included severity of illness, household proximity to a health facility, and knowledge of malaria prevention methods. Our results indicate that there is an important role for the formal health care system in mitigating morbidity and mortality and reducing transmission during malaria epidemics in Uganda.

Arthroscopic Bankart repair of anterior detachments of the glenoid labrum. A prospective study.

BACKGROUND: The purpose of this study was to evaluate the results of an arthroscopic transglenoid suture-stabilization procedure in athletically active patients who had recurrent, unilateral, unidirectional anterior dislocations of the shoulder and an isolated anterior detachment of the glenoid labrum. METHODS: Forty-one patients who had unilateral, unidirectional anterior dislocations of the shoulder and an isolated anterior detachment of the glenoid labrum were managed with arthroscopic repair. All patients were athletic, and seventeen of the male patients were football players. No patient had inferior or posterior laxity or a posterior detachment. The sutures were anchored to the posterior aspect of the scapula, and the knots were tied anteriorly to secure the detached region of the labrum and the inferior glenohumeral ligament to the anterior aspect of the scapula. The mean duration of follow-up was fifty-two months (range, twenty-five months to seven years). The patients were evaluated annually with a physical examination, radiographs, isokinetic strength-testing, the modified shoulder-rating scale of Rowe and Zarins, and the scoring system of the American Shoulder and Elbow Surgeons. RESULTS: Forty (98 percent) of the forty-one athletes returned to their preoperative sport postoperatively. Thirty-nine patients (95 percent) had no additional dislocations or subluxations, and two (5 percent), both of whom were football players, had a single episode of subluxation. Thirty-seven patients (90 percent) had a score of at least 80 points on the scale of Rowe and Zarins, and thirty-four (83 percent) had a score of at least 90 points. Thirty-nine patients (95 percent) had a score of at least 80 points on the scale of the American Shoulder and Elbow Surgeons, and twenty-five (61 percent) had a score of at least 90 points. Lower scores were associated with loose bodies seen on arthroscopy (p = 0.001), osseous lesions seen on postoperative radiographs (p = 0.036), and subluxation (p = 0.000). Twenty-two shoulders (54 percent) had a full range of motion in all planes, and eighteen (44 percent) had no strength deficit in any position on isokinetic testing. With the numbers available for study, no significant association was found between the presence of a Hill-Sachs or an osseous Bankart lesion on preoperative radiographs and the overall score on the scale of Rowe and Zarins or the scale of the American Shoulder and Elbow Surgeons; however, there was a significant association between the range of motion and an osseous Bankart lesion on preoperative radiographs (p = 0.002) and between decreased strength on isokinetic testing and a Hill-Sachs lesion on preoperative radiographs and an osseous lesion on postoperative radiographs (p = 0.022). There also was a significant association between a decreased range of motion (p < 0.002) and decreased strength (p = 0.014) and the arthroscopic finding of loose bodies. Muscle strength also was affected by arm dominance and the number of preoperative dislocations. CONCLUSIONS: Arthroscopic transglenoid repair of isolated anterior labral detachments restored stability of the shoulder and led to a favorable outcome in thirty-nine (95 percent) of the forty-one athletes. Only the two football players who had postoperative subluxation had a score of less than 80 points according to the scale of the American Shoulder and Elbow Surgeons.

Dopamine D1/D2 agonists injected into nucleus accumbens and ventral pallidum differentially affect locomotor activity depending on site.

Ventral pallidal dopamine has been recently shown to play an important role in psychostimulant reward and locomotor activation. The aim of the present study was to compare the roles of ventral pallidal D1 and D2 receptors in evoking locomotor activity with those in the nucleus accumbens. The D1 agonist SKF 38393 and the D2 agonist quinpirole hydrochloride (0.3-3 microg/ 0.5 microl) were bilaterally injected into ventral pallidum or nucleus accumbens through pre-implanted cannulae. In the ventral pallidum, 0.3-1 microg SKF 38393 increased locomotor activity while 3 microg had no effect; 3 microg quinpirole suppressed locomotion while 0.3-1 microg had no effect. Locomotor activity induced by an equigram (0.3 microg) mixture of SKF 38393 and quinpirole, while significantly higher than that induced by 0.3 microg quinpirole was not significantly higher than that induced by 0.3 microg SKF 38393 alone. At the 3 microg dose, SKF 38393 injections into anterior ventral pallidum increased activity; injections into posterior ventral pallidum decreased activity. In the nucleus accumbens, 0.3-3 microg SKF 38393 dramatically increased locomotor activity while quinpirole moderately increased locomotion. In the group that had previously received the full quinpirole dose range, injection of the equigram (0.3 microg) mixture of SKF 38393 and quinpirole induced locomotor activation which was higher than that induced by either drug alone or by the addition of the effect of each drug alone, i.e. synergy occurred. Moreover, rats that had previously received SKF 38393 developed a sensitized locomotor response to subsequent SKF 38393, quinpirole or the mixture of these two drugs. The difference in locomotor response to dopamine agonists between the ventral pallidum and nucleus accumbens is consistent with electrophysiological evidence collected at these two sites. These findings suggest that, unlike the nucleus accumbens, where D1 and D2 receptor activation may facilitate each other to induce a synergistic effect on locomotor activity, ventral pallidal D1 and D2 receptors may be located on different neurons and coupled with different, if not opposite, behavioral output.

GABAergic modulation of ventral pallidal dopamine release studied by in vivo microdialysis in the freely moving rat.

The mesopallidal dopamine system, which originates from the ventral tegmental area and projects to the ventral pallidum (VP), has been recently shown to play an important role in self-stimulation reward and cocaine reward. VP also receives a GABAergic projection from nucleus accumbens (NAS). The aim of the present study was to examine the involvement of this GABAergic projection in the modulation of VP dopamine release. Both the GABAA antagonist picrotoxin (2-200 microM) and the GABAB antagonist phaclofen (20-2,000 microM), perfused locally, dose-responsively increased VP extracellular dopamine 2-2.5-fold. Cocaine (10 microM) produced a 6.5-fold increase of VP dopamine. Neither picrotoxin (200 microM), phaclofen (2,000 microM), nor GABA (20-2,000 microM) altered the response of VP dopamine to locally applied cocaine. GBR 12909 (0.5 microM), a selective dopamine uptake blocker, induced a 3.5-fold increase of VP dopamine. The increase of VP dopamine in response to GBR 12909 was further augmented to 8.5-fold of baseline when picrotoxin (200 microM) was added to the perfusate. The data from the present study demonstrate that the GABAergic NAS-VP projection can modulate ventral pallidal dopamine release. However, the effect of GABA on the mesopallidal dopamine system's response to locally applied cocaine may be complicated by actions of cocaine other than dopamine uptake inhibition.

Open lateral retinacular lengthening compared with arthroscopic release. A prospective, randomized outcome study.

A prospective, randomized study was performed to compare the results of arthroscopic lateral retinacular release (Group I) with those of open lateral retinacular lengthening (Group II). The study included eighty-six patients (eighty-six knees) who had had pain in the anterior peripatellar aspect of the knee and lateral patellar tilting (rotational malalignment), as seen on Merchant tangential patellofemoral radiographs, that had not improved after participation in a structured rehabilitation program for the quadriceps and the hamstrings for a minimum of six months. The mean duration of follow-up after the operative procedures was forty-six months (range, two to six years). At the time of the latest follow-up evaluation, forty (93 per cent) of the forty-three patients in Group I and all forty-three (100 per cent) of the patients in Group II had resumed the level of athletic activity that they had engaged in before the onset of symptoms (p = 0.08, analysis of variance). With the numbers available for study, no significant difference could be detected between the groups with regard to deficits in the range of motion, atrophy (the circumference) of the thigh, operative or postoperative complications, or the need for subsequent operative procedures. Additionally, no significant difference could be detected between the groups with regard to the results of open or closed-chain testing with an isokinetic dynamometer. According to the knee-rating system of Lysholm and Gillquist as modified by Tegner and Lysholm, thirty-three knees (77 per cent) in Group I had a score of 80 points or more compared with thirty-eight knees (88 per cent) in Group II. Six knees (14 per cent) in Group I had a score of less than 70 points compared with no knees in Group II. The difference in the knee ratings between the two groups was significant (p = 0.028, analysis of variance). Although there seemed to be a definite trend toward improved function of the knee in association with a longer duration of follow-up, no significant association could be detected between the duration of follow-up and improvement in the outcome measures in either group.

Arthroscopically assisted reconstruction of the anterior cruciate ligament. A prospective randomized analysis of three techniques.

One hundred and twenty-seven patients who had a rupture of the anterior cruciate ligament agreed to participate in a prospective, randomized study of three arthroscopically assisted reconstruction techniques. One hundred and twenty-five patients (125 reconstructions) were evaluated after a mean duration of follow-up of forty-two months (range, two to five years). Group I included forty patients who had a two-incision reconstruction with use of an autogenous semitendinosus-gracilis graft, group II consisted of forty patients who had a two-incision reconstruction with use of an autogenous patellar-ligament graft, and group III included forty-five patients who had a single-incision reconstruction (endoscopic technique) with use of an autogenous patellar-ligament graft. The male-female ratio, age range, level of athletic activity, interval between the injury and the reconstruction, previous operative procedures, and associated injuries were similar in all three groups. The same postoperative rehabilitation protocol was followed for all patients. Testing with a KT-2000 arthrometer at maximum manual force was done at the follow-up evaluation; the difference in laxity between the involved knee and the contralateral knee was three millimeters or less in thirty-three patients (83 per cent) in group I, thirty-seven patients (93 per cent) in group II, and thirty-nine patients (87 per cent) in group III. A difference of two millimeters or less was found in thirty patients (75 per cent) in group I, thirty-one patients (78 per cent) in group II, and thirty-five patients (78 per cent) in group III. Thirty-five patients (88 per cent) in group I, thirty-eight patients (95 per cent) in group II, and forty patients (89 per cent) in group III returned to at least the same level of athletic activity. Four grafts (two in group I and two in group II) failed as a result of trauma. There was one additional failure in groups I and III, as evidenced by a difference of nine and seven millimeters, respectively, on instrumented testing of laxity. The significant findings were that no knee was rated D according to the system of the International Knee Documentation Committee (p < 0.002, 94 per cent confidence level) and that fewer additional operative procedures were done on patients in group III (p < 0.08). Also, it was found that the patients in group II returned to a greater level of athletic activity (p < 0.02) and that a higher percentage of the patients in this group had a difference of three millimeters or less on testing with the KT-2000 arthrometer than in the other two groups (p < 0.08). However, with the numbers available, there were no significant differences in the over-all outcome among the three groups (p > 0.1). Importantly, the rate of failure was not greater and the outcomes were not less satisfactory for the late reconstructions than they were for the acute reconstructions (those performed less than three weeks after the injury), including those done with an autogenous semitendinosus-gracilis graft in a chronically unstable knee.

Locomotor response to novelty does not predict cocaine place preference conditioning in rats.

Previous studies have demonstrated that rats showing a strong locomotor response to a novel environment have a greater locomotor response to psychostimulant drugs and more rapidly acquire intravenous self-administration of amphetamine. In this report, we examined whether these high-responder (HR) rats would develop place-preference conditioning with cocaine more readily than low-responder (LR) rats. Neither group of rats developed conditioned place preference for cocaine, 2.5 mg/kg, intraperitoneally (IP). Both groups of rats developed conditioned place preference for cocaine, 5.0 and 15 mg/kg, IP. However, we could not find any evidence of enhanced conditioning in the HR rats. HR rats did show a greater locomotor response to cocaine, 15 mg/kg, IP, and the locomotor response of HR and LR rats to cocaine correlated with their response to a novel environment. We conclude that using the place-preference procedure, HR and LR rats do not differ in the rewarding effect of cocaine.

Locomotor response to novelty does not predict cocaine place preference conditioning in rats.

Previous studies have demonstrated that rats showing a strong locomotor response to a novel environment have a greater locomotor response to psycho-stimulant drugs and more rapidly acquire intravenous self-administration of amphetamine. In this report, we examined whether these high-responder (HR) rats would develop place-preference conditioning with cocaine more readily than low-responder (LR) rats. Neither group of rats developed conditioned place preference for cocaine, 2.5 mg/kg, intraperitoneally (IP). Both groups of rats developed conditioned place preference for cocaine, 5.0 and 15 mg/kg, IP. However, we could not find any evidence of enhanced conditioning in the HR rats. HR rats did show a greater locomotor response to cocaine, 15 mg/kg, IP, and the locomotor response of HR and LR rats to cocaine correlated with their response to a novel environment. We conclude that using the place-preference procedure, HR and LR rats do not differ in the rewarding effect of cocaine.

Increased sensitivity to cocaine place-preference conditioning by septal lesions in rats.

Rats bearing electrolytic lesions of medial septum and sham-operated controls were trained on cocaine place-preference in a 3-compartment apparatus. Cocaine was paired with a white or a black compartment. An unbiased design was used, in which cocaine was paired with the preferred side in half the animals and with the unpreferred side in the other half. Two low doses of cocaine HCl were used: 2.5 and 5.0 mg/kg. Only two pairings of drug with environment were used to minimize the influence of drug sensitization. Rats with septal lesions, but not controls, showed preference conditioning to the black side at 2.5 mg/kg; lesioned and control animals showed similar conditioning to the black side at 5.0 mg/kg. Lesioned animals could not be conditioned to the white side at either dose. This was attributed to a drug-induced enhancement of a previously described increased reactivity to brightness following septal lesions. Controls conditioned to either side at 5.0 mg/kg. It was concluded that septal lesions lowered the cocaine dose required for preference conditioning, consistent with reports that such damage enhances some behavioral effects of psychostimulants.

Assessment of the relative contribution of peripheral and central components in cocaine place conditioning.

A balanced place conditioning paradigm was used to assess the contribution of peripheral and central factors mediating place conditioning induced by cocaine HCl. The first experiment was conducted to examine changes in locomotor activity and extracellular dopamine (DA) concentrations in the nucleus accumbens (NACC) following intraperitoneal (IP) injections of cocaine HCl (15 mg/kg) or cocaine methiodide (19.6 mg/kg). IP cocaine HCl significantly increased locomotor activity and extracellular NACC DA, whereas IP cocaine methiodide failed to increase either locomotor activity or extracellular DA in the NACC. In the second experiment, IP cocaine HCl (15 mg/kg) induced a significant conditioned place preference; however, neither IP procaine HCl (25 or 50 mg/kg) nor IP cocaine methiodide (4.9, 9.8, or 19.6 mg/kg) induced preferences for the drug-paired compartment. In the third experiment, intracerebroventricular (ICV) infusions of cocaine HCl (25 micrograms/2 microliters) or cocaine methiodide (1 or 5 micrograms/2 microliters) induced significant place conditioning for the drug-paired compartment. These results suggest place conditioning induced by cocaine HCl is mediated centrally and that the local anaesthetic properties alone do not contribute to this effect to any significant degree.

Individual differences in schedule-induced and conditioned behaviors.

Previous experiments have shown that subjects which exhibit a high locomotor response to novelty (HR) also show a greater locomotor response to psychomotor stimulants than subjects which have a low locomotor response to a novel environment (LR). The current experiments were designed to examine in more detail the behavioral differences between HR and LR rats in non-drug paradigms. In the first experiment HR rats acquired schedule-induced polydipsia (SIP) more readily than LR rats. Panel pressing to gain access to the food pellets, however, was greater in LR rats compared to HR rats, especially after stable levels of SIP had been attained. In the second experiment one group of rats were fed daily after a 30-min period in photocell-cages (food conditioning; FC) while a control group was fed in the home-cage (non-conditioned; NC). FC subjects developed heightened locomotor activity in anticipation of feeding in the initial 30 min in the test-cage compared to NC rats. This anticipatory locomotor activity developed more rapidly and to a greater level in HR rats than in LR rats. The concentrations of dopamine, dihydroxyphenylacetic acid, homovanillic acid, serotonin, 5-hydroxyindoleacetic acid, and norepinephrine were determined at the completion of behavioral testing in both the food conditioned and non-conditioned rats. The food conditioned experiment showed that variations in both the dopaminergic and serotoninergic systems may underlie individual differences in behavioral responsiveness. However, no clear pattern of neurochemical differences emerged. The current set of experiments have demonstrated differences between HR and LR rats in non-drug related paradigms and that HR rats appear to show a greater motivational excitement induced by periodic food delivery than LR rats.

Patellofemoral stress syndrome. Current concepts.

Patellofemoral stress syndrome is a condition of peripatellar pain without anatomic malalignment, history of trauma, patellar instability or clinical evidence of patellofemoral crepitus. These patients demonstrate lateral retinacular and iliotibial band tightness. Frequently, the patient's pain occurs when sitting for prolonged periods of time with the knee flexed, and most commonly with sporting events. A complete history and physical evaluation is necessary for an accurate diagnosis. This evaluation should include the following radiographs: anterior-posterior, lateral, and most importantly, the tangential views. Once diagnosed, patellofemoral stress syndrome is usually treated conservatively. Studies indicate that 60 to 80% of knees will respond favourably to conservative treatment. The exercise programme should include iliotibial band stretching, hamstring stretching, gastrocnemius stretching, progressive resistance straight leg raising and hip adduction strengthening. These exercises should be performed 2 times/day until symptoms subside and then 3 times/week as long as the patient is active in sports. If the conservative programme fails, surgical management may be considered. A lateral retinacular release or possibly lateral retinacular lengthening are surgical procedures recommended as reliable solutions in the majority of patients. These procedures require continuation of the exercise programme to be successful.

Decreased raphe unit activity in a rat model of endogenous depression.

One theory about the pathogenesis of endogenous depression is that decreased serotonergic (5-HT) neurotransmission is involved in producing the disorder. A key component of brain 5-HT neurotransmission is the discharge rate of 5-HT neurons in the dorsal raphe nucleus (DRN), a major aggregation of 5-HT neurons. We tested the hypothesis that the discharge rate of 5-HT neurons in the DRN was decreased in a new animal (rat) model of human endogenous depression. In this model, rats are treated neonatally with the antidepressant chlorimipramine. When adult, these animals exhibit several behavioral, REM sleep, and treatment response features of the human disorder. We found in a single unit measurements in adult, pentobarbital-anesthetized rats that, compared with 'non-depressed' control rats, the 'depressed' rats had a lower discharge rate of 5-HT neurons in the DRN. This correlation is consistent with the theory that 5-HT neurotransmission is diminished in endogenous depression.

6-Hydroxydopamine lesions of the medial prefrontal cortex fail to influence cocaine-induced place conditioning.

This study investigated the involvement of medial prefrontal cortex (mPFC) dopamine in cocaine place conditioning using a totally balanced place conditioning design. Presynaptic dopamine terminals of the mPFC were lesioned by bilaterally infusing the selective neurotoxin 6-hydroxydopamine (6-OHDA). These lesions significantly depleted dopamine (-83%) and norepinephrine (-70%) in the mPFC but there were no significant reductions in either the nucleus accumbens or in the caudate-putamen compared with sham-operated controls. Furthermore, serotonin levels were not affected in any of the brain regions investigated. These lesions failed to attenuate place conditioning induced by the intraperitoneal (i.p. 10 mg/kg) administration of cocaine when compared to sham lesioned controls. In addition, there were no significant differences in spontaneous locomotor activity between the two groups during the preconditioning phase or the test phase. These results suggest that 6-OHDA lesions which produced profound depletions of dopamine and norepinephrine in the mPFC did not alter the rewarding efficacy of cocaine as measured by the place conditioning paradigm.

Patellofemoral stress. A prospective analysis of exercise treatment in adolescents and adults.

Thirty patients, 13 skeletally immature individuals and 17 adults, participated in a prospective study designed to evaluate the effect of isometric quadriceps strengthening exercises on patellofemoral pain. Of the 30 patients with anatomically normal lower extremity alignment and no history of previous knee trauma or surgery, there were 34 knees that had a decrease in peripatellar knee pain with a structured exercise program. One additional patient had a decrease in pain after an arthroscopic lateral release and with continued exercises. An equal number of skeletally immature patients and adults had a decrease in peripatellar knee pain. However, 5 of the 17 adults had to limit their activities, while no adolescent patient had to limit activity. Additionally, eight skeletally immature knees had greater than 5 degrees change in their congruence angles, as measured on Merchant tangential radiographs, over the year-long course of this study. Only one adult knee had a similar radiographic improvement. We recommend immediate action to alleviate patellofemoral pain syndrome, even when extremity alignment is normal. An isometric, progressive resistance quadriceps program with iliotibial band and hamstring stretching exercises is the preferred initial treatment.

Conditioned locomotor activity but not conditioned place preference following intra-accumbens infusions of cocaine.

In the first experiment, the conditioned place preference (CPP) paradigm was used to examine the rewarding properties of bilateral microinfusions of cocaine HCl into the nucleus accumbens (0, 12.5, 25, 50, or 100 micrograms). No dose of intra-accumbens cocaine induced a significant CPP. However, bilateral intra-accumbens infusions of d-amphetamine sulfate (10 micrograms) or intraperitoneal administration of cocaine HCl (5 or 10 mg/kg) both produced a significant preference for the drug-paired compartment. In the second experiment, the ability of bilateral intra-accumbens infusions of cocaine HCl (50 micrograms) to elicit conditioned locomotor activity (CLA) was examined. During the conditioning trials, intra-accumbens cocaine significantly increased locomotor activity. On the test day, when no drug was administered, the group that had previously received cocaine in the activity chamber showed significantly greater locomotor activity than the vehicle control group. This demonstration of CLA indicates that rats are able to associate the effects of intra-accumbens infusions of cocaine with environmental stimuli; however, these infusions are not rewarding as measured by the CPP paradigm. In addition, these results may indicate important differences between the neural substrates for cocaine and amphetamine reward and reveal a dissociation between CPP and CLA.