HPLC Determination of Total Tryptophan in Infant Formula and Adult/Pediatric Nutritional Formula Following Enzymatic Hydrolysis: Single-Laboratory Validation, First Action 2017.03.

A method for tryptophan (Trp) analysis designed to comply with AOAC Standard Method Performance Requirement 2014.013 is described. Unlike AOAC 988.15, which uses alkaline hydrolysis, this method uses enzymatic hydrolysis to release the Trp from the intact protein. The method achieves an LOQ of 0.18 mg/100 g Trp on a ready-to-feed basis with mean recoveries ranging from 93.8 to 104.9%. Repeatability ranged from 0.2 to 5.0%. Intermediate precision ranged from 1.0 to 6.9%. The analytical range was determined to be 0.18-300 mg/100 g, with linearity over eight calibration standard levels giving an average deviation from theoretical levels of 0.3%. No single calibration point had a deviation of >5.0%. Two standard reference materials (SRMs 1849a and 927e) were analyzed, and the average deviation from the certified value was 98.5% for SRM 1849a and 101.2% for SRM 927e. Sample preparation is very similar to existing methods in terms of time and complexity. The use of an internal standard reduces laboratory error and allows for reproducible results.

Learning not to respond: Role of the hippocampus in withholding responses during omission training.

Autoshaping is a Pavlovian learning paradigm in which rats experience pairings of a CS and a US independently of their behavior. When the CS is a lever inserted into the test cage and the US is food delivered to an adjacent magazine, many rats acquire a lever-pressing response called 'sign-tracking' even though that response has no effect on the occurrence of either the CS or the US. Since these lever presses are always followed by the US, it has been suggested that sign-tracking could be due to unintended reinforcement of the response. To eliminate the possibility of such instrumental learning the omission schedule, in which a response to the CS cancels the US, was introduced. Previous research has shown that training rats on autoshaping and switching them to an omission schedule generally reduces but does not eliminate sign-tracking, suggesting that it may be due to both Pavlovian and instrumental learning. In the present study naive rats trained on an omission schedule sign-tracked less than a control group exposed to random, unpaired CS and US presentations, suggesting that they learned to withhold the lever press response because of the negative contingency between that response and the US. In a second experiment rats with dorsal hippocampus lesions sign-tracked more than sham-lesioned rats on omission schedules, suggesting that this case of learning not to respond is hippocampus-based. This conclusion is consistent with many previous findings on the inability of hippocampal rats to withhold or suppress responding, and with studies suggesting that one form of extinction of learned responses in normal rats is due to competition from hippocampus-based learning not to respond.

Translating Occupational Justice Education Into Action: Reflections From an Exploratory Single Case Study.

There is a growing body of scholarly literature about occupational justice, human rights, and power redistribution ready to be integrated into occupational science and occupational therapy education. As students around the world become familiar with the concepts and intents underlying occupational justice, it will be important to investigate their translation of occupational justice understandings into actions outside the classroom. This exploratory single case study describes curricular, university, and regional factors related to one former student's engagement in social protests following her occupational justice education. Based on her reflections, we emphasize the need to provide classroom opportunities where students can apply and critically reflect on (a) knowledge about occupational justice and (b) unintended consequences and potential professional tensions that may arise in relation to pursuing occupational justice. Future research will benefit from broader comparative studies that analyze personal, contextual, and programmatic differences among instances of occupational justice education and students' engagement in occupational reconstructions.

Parallel learning in an autoshaping paradigm.

In an autoshaping task, a single conditioned stimulus (CS; lever insertion) was repeatedly followed by the delivery of an unconditioned stimulus (US; food pellet into an adjacent food magazine) irrespective of the rats' behavior. After repeated training trials, some rats responded to the onset of the CS by approaching and pressing the lever (sign-trackers). Lesions of dorsolateral striatum almost completely eliminated responding to the lever CS while facilitating responding to the food magazine (US). Lesions of the dorsomedial striatum attenuated but did not eliminate responding to the lever CS. Lesions of the basolateral or central nucleus of the amygdala had no significant effects on sign-tracking, but combined lesions of the 2 structures impaired sign-tracking by significantly increasing latency to the first lever press without affecting the number of lever presses. Lesions of the dorsal hippocampus had no effect on any of the behavioral measures. The findings suggest that sign-tracking with a single lever insertion as the CS may consist of 2 separate behaviors learned in parallel: An amygdala-mediated conditioned orienting and approach response and a dorsal striatum-mediated instrumental response. (PsycINFO Database Record

Exposure to Pre- and Perinatal Risk Factors Partially Explains Mean Differences in Self-Regulation between Races.

OBJECTIVES: To examine whether differential exposure to pre- and perinatal risk factors explained differences in levels of self-regulation between children of different races (White, Black, Hispanic, Asian, and Other). METHODS: Multiple regression models based on data from the Early Childhood Longitudinal Study, Birth Cohort (n ≈ 9,850) were used to analyze the impact of pre- and perinatal risk factors on the development of self-regulation at age 2 years. RESULTS: Racial differences in levels of self-regulation were observed. Racial differences were also observed for 9 of the 12 pre-/perinatal risk factors. Multiple regression analyses revealed that a portion of the racial differences in self-regulation was explained by differential exposure to several of the pre-/perinatal risk factors. Specifically, maternal age at childbirth, gestational timing, and the family's socioeconomic status were significantly related to the child's level of self-regulation. These factors accounted for a statistically significant portion of the racial differences observed in self-regulation. CONCLUSIONS: The findings indicate racial differences in self-regulation may be, at least partially, explained by racial differences in exposure to pre- and perinatal risk factors.

Poor sleep and reactive aggression: Results from a national sample of African American adults.

BACKGROUND: We know that poor sleep can have important implications for a variety of health outcomes and some evidence suggests a link between sleep and aggressive behavior. However, few studies have looked at this relationship among African-Americans in the United States. METHODS: Data from the National Survey of American Life (NSAL) and the NSAL Adult Re-Interview were used to examine associations between sleep duration and self-reported quality of sleep on reactive aggression among African American and Caribbean Black respondents between the ages of 18 and 65 (n = 2499). RESULTS: Controlling for an array of sociodemographic and psychiatric factors, sleep was found to be significantly associated with reactive aggression. Specifically, individuals who reported sleeping on average less than 5 h per night were nearly three times more likely to report losing their temper and engaging in a physical fight (AOR = 3.13, 95% CI = 1.22-8.02). Moreover, individuals who reported being "very dissatisfied" with their sleep were more than two times more likely to report losing their temper and engaging in physical fights (AOR = 3.32, 95% CI = 1.50-7.33). Persons reporting everyday discrimination and problems managing stress were more likely to sleep poorly. CONCLUSIONS: The present study is among the first to document an association between poor sleep and reactive violence among African-Americans. Findings suggest that reducing discrimination may lead to improved sleep and subsequently reduce forms of reactive violence.

Dissociation of memory systems: The story unfolds.

In this article we describe the ideas and circumstances that led to the experiment demonstrating a triple dissociation of memory systems. We then move on to discuss the results of 20 years of investigation of those ideas. First, evidence is described from animal studies consistent with the ideas that memory for different kinds of information is stored in different brain systems, and that the hippocampus, amygdala, and dorsal striatum are each central structures in one of the systems. We then focus on the 3 tasks used in the original triple dissociation: win-stay learning, conditioned cue preference, and win-shift learning. Each of these tasks is specific to behavior resulting from the type of information stored in one of the systems, but the use of other behavioral tests that are sensitive to the types of information stored in other systems has revealed that, in each case, other types of information are acquired in parallel. Next, evidence consistent with the idea that the outputs of the systems compete for control of behavior is discussed together with alternative forms of more direct interactions among the systems. Finally, some evidence that many of these ideas about multiple parallel memory systems may apply to humans is reviewed.

A triple dissociation of memory systems: Hippocampus, amygdala, and dorsal striatum.

This study investigated the respective roles of the hippocampus, the amygdala, and the dorsal striatum in learning and memory. A standard set of experimental conditions for studying the effects of lesions to the three brain areas using an 8-arm radial maze was used: a win-shift version, a conditioned cue preference (CCP) version, and a win-stay version. Damage to the hippocampal system impaired acquisition of the win-shift task but not the CCP or win-stay tasks. Damage to the lateral amygdala impaired acquisition of the CCP task but not the win-shift or win-stay tasks. Damage to the dorsal striatum impaired acquisition of the win-stay task but not the win-shift or CCP tasks. These results are consistent with the hypothesis that the mammalian brain may be capable of acquiring different kinds of information with different, more-or-less independent neural systems. A neural system that includes the hippocampus may acquire information about the relationships among stimuli and events. A neural system that includes the amygdala may mediate the rapid acquisition of behaviors based on biologically significant events with affective properties. A neural system that includes the dorsal striatum may mediate the formation of reinforced stimulus-response associations.

Memory enhancement produced by post-training exposure to sucrose-conditioned cues.

A number of aversive and appetitive unconditioned stimuli (such as shock and food) are known to produce memory enhancement when they occur during the post-training period. Post-training exposure to conditioned aversive stimuli has also been shown to enhance memory consolidation processes. The present study shows for the first time that post-training exposure to conditioned stimuli previously paired with consumption of a sucrose solution also enhances memory consolidation. Male Long Evans rats were trained on a one-session conditioned cue preference (CCP) task on a radial arm maze. Immediately or 2 hours after training, rats consumed a sucrose solution or were exposed to cues previously paired with consumption of sucrose or cues previously paired with water. Twenty-four hours later, the rats were tested for a CCP. Immediate, but not delayed, post-training consumption of sucrose enhanced memory for the CCP. Immediate, but not delayed, post-training exposure to cues previously paired with sucrose, but not with water, also enhanced CCP memory. The possibility that rewarding and aversive conditioned stimuli affect memory by a common physiological process is discussed.

Parallel processing of information about location in the amygdala, entorhinal cortex and hippocampus.

The conditioned cue preference paradigm was used to study how rats use extra-maze cues to discriminate between 2 adjacent arms on an 8-arm radial maze, a situation in which most of the same cues can be seen from both arms but only one arm contains food. Since the food-restricted rats eat while passively confined on the food-paired arm no responses are reinforced, so the discrimination is due to Pavlovian stimulus-reward (or outcome) learning. Consistent with other evidence that rats must move around in an environment to acquire a spatial map, we found that learning the adjacent arms CCP (ACCP) required a minimum amount of active exploration of the maze with no reinforcers present prior to passive pairing of the extra-maze cues with the food reinforcer, an instance of latent learning. Temporary inactivation of the hippocampus during the pre-exposure sessions had no effect on ACCP learning, confirming other evidence that the hippocampus is not involved in latent learning. A series of experiments indentified a circuit involving fimbria-fornix and dorsal entorhinal cortex as the neural basis of latent learning in this situation. In contrast, temporary inactivation of the entorhinal cortex or hippocampus during passive training or during testing blocked ACCP learning and expression, respectively, suggesting that these two structures co-operate in using spatial information to learn the location of food on the maze during passive pairing and to express this combined information during testing. In parallel with these processes we found that the amygdala processes information leading to an equal tendency to enter both adjacent arms (even though only one was paired with food) suggesting that the stimulus information available to this structure is not sufficiently precise to discriminate between the ambiguous cues visible from the adjacent arms. Expression of the ACCP in normal rats depends on hippocampus-based learning to avoid the unpaired arm which competes with the amygdala-based tendency to enter that arm. In contrast, there is cooperation between amygdala- and hippocampus-based tendencies to enter the food-paired arm. These independent forms of learning contribute to the rat's ability to discriminate among spatial locations using ambiguous extra-maze cues.

Effects of post-training heroin and d-amphetamine on consolidation of win-stay learning and fear conditioning.

It has been proposed that the reinforcing properties of drugs of abuse are due, in part, to their ability to enhance memory consolidation. To test this hypothesis, heroin (0.03-3 mg/kg, SC) and d-amphetamine (0.5-2 mg/kg, SC) were administered to male Sprague-Dawley rats immediately or 4 h after training on win-stay and fear conditioning tasks. On the win-stay, immediate post-training administration of lower doses of heroin and d-amphetamine enhanced acquisition, and probe tests further revealed that these drugs enhanced different aspects of learning. Higher doses had no effect or impaired performance, particularly when administered repeatedly. On fear conditioning, the memory-enhancing effects of immediate post-training administration of lower heroin and d-amphetamine doses were revealed only when a single tone-shock pairing procedure was employed. Therefore, under appropriate experimental conditions, mildly stimulatory doses of heroin and d-amphetamine enhanced the acquisition of tasks thought to involve different types of learning. These results support the hypothesis that one of the ways in which drugs of abuse such as opiates and psychomotor stimulants reinforce behavior is by enhancing memory consolidation processes.

Lesions of basolateral and central amygdala differentiate conditioned cue preference learning with and without unreinforced preexposure.

In the separated arms conditioned cue preference (CCP) task rats are trained by confining them in one arm of an eight-arm radial maze with food and in another arm on the opposite side of the maze with no food on alternate days. After two such trials, rats prefer the food-paired arm when allowed to move freely between the two arms, neither of which contains food. However, if the rats are preexposed to the maze by exploring it without food before training, no preference is observed and at least 4 training trials are required to produce a CCP, suggesting that unreinforced preexposure to the maze latently inhibits acquisition. If this interpretation is correct, preexposure should reduce the size of the preference acquired with both 2 and 4 training trials. In Experiment 1, this prediction was replicated for 2 training trials; however, with 4 training trials, eliminating preexposure also eliminated the CCP. A previous finding that basolateral amygdala lesions impair the CCP with preexposure and 4 training trials was replicated in Experiment 2, but similar lesions had no effect on the CCP in non-preexposed rats given 2 training trials. In contrast, lesions of the central nucleus impaired the 2 training trial CCP but had no effect on the 4 training trial CCP. This double dissociation suggests that the BLA-mediated 4 training trial CCP may be due to learning about the reward features of the maze space, while the central-nucleus-mediated 2 training trial CCP may be due to a conditioned approach response.

Ultrasonic vocalization ratios reflect the influence of motivational state and amygdala lesions on different types of taste avoidance learning.

Consumption of a sweet solution (the CS) and ultrasonic vocalizations (USVs) emitted by rats were recorded in a conditioned taste avoidance paradigm. The rats' affective states were inferred from a ratio of high to low-frequency ultrasonic calls, which have been associated with positive and negative affect, respectively. The interacting effects of deprivation state and lesions of the basolateral amygdala (BLA) on CS consumption and affective state were examined. Rats were trained during the light phase while either 23 h or 3h water deprived by exposing them to the CS and then injecting them with LiCl or saline. They were tested by re-exposing them to the CS while either 23 or 3h deprived. Sham-lesioned rats that received LiCl injections consumed significantly less of the CS and evidenced relatively negative affect (inferred from the USV ratio) compared to control rats that received saline injections, regardless of the deprivation state in which they were trained or tested. Rats with BLA lesions trained while 23 h deprived failed to exhibit either reduced consumption or negative affect, regardless of whether they were tested while deprived for 23 or 3h. Identical lesions had no effect on reduced consumption or on negative affect in rats trained while 3h deprived, regardless of whether they were tested while deprived for 3 or 23 h. The findings suggest that both reduced consumption and negative affect are the results of different learning processes in deprived (23 h) and nearly satiated (3h, during the light phase) rats. The amygdala-dependent negative affective shift observed in deprived rats may be due to an aversive Pavlovian conditioned response that acts to suppress drinking. The amygdala-independent negative affective response and reduced consumption in nearly satiated rats could be due to a form of latent learning of a stimulus-outcome association.

Temporary inactivation of the dorsal entorhinal cortex impairs acquisition and retrieval of spatial information.

We tested the effects of temporary inactivation of the dorsal entorhinal cortex on spatial discrimination using a conditioned cue preference (CCP) paradigm. The three phases of the procedure were: pre-exposure: unreinforced exploration of the center platform and two adjacent arms of an eight-arm radial maze; training: rats were confined to the ends of the two arms on alternate days - one arm always contained food and the other never contained food; testing: unreinforced exploration of the center platform and the two arms. Rats that received bilateral infusions of saline into the dorsal entorhinal cortex before the training trials or before the test trial spent significantly more time in the arm that previously contained food than in the arm that never contained food, demonstrating that they had acquired and were able to express information that discriminated between the two adjacent maze arms. In contrast, rats that received bilateral, intra-entorhinal infusions of muscimol, a gamma-aminobutyric acid(a) (GABA(a)) agonist, before either training or testing spent equal amounts of time in the two arms, indicating that they failed to acquire and were unable to express this information. Interactions between the entorhinal cortex and hippocampus in the acquisition and expression of the information required for this discrimination are discussed.

Impact of RSV: implications for managed care.

Severe RSV disease, manifested as bronchiolitis or pneumonia, is the leading cause of hospitalization of infants younger than 1 year of age in the United States. Infants born 35 weeks or less GA are particularly at high risk of severe RSV disease, which may result in frequent NICU admissions or long hospital stays and additional health care utilization over the first 12 months of life. This care is costly--infants 33 to 36 weeks GA with a history of RSV hospitalization incur costs that are nearly 5 times as much as costs for 33 to 36 weeks GA infants with no history of RSV hospitalization. Managed care payers should be cognizant of the potential ramifications of severe RSV disease in infants. Developing a proactive RSV management strategy can help improve health outcomes and reduce unnecessary hospital resource use.

Some highlights of research on the effects of caudate nucleus lesions over the past 200 years.

This review describes experiments on the effects of caudate nucleus lesions on behavior in monkeys, cats and rats. Early work on monkeys and cats focused on the relationship of the caudate to the cortex in motor control, leading to the idea that the caudate serves to inhibit behaviors initiated by the cortex. However, investigation of this hypothesis with systematic behavioral testing in all three species did not support this idea; rather, these studies provided evidence that caudate lesions affect memory functions. Two main types of memory tasks were affected. One type involved reinforced stimulus-response (S-R) associations, the other involved spatial information, response-reinforcer contingencies, or working memory. Recent evidence, mainly from rats, suggests that the dorsolateral part of the caudoputamen is central to the processing and consolidation of memory for reinforced S-R associations, and that the more medial and anterior parts of the same structure are part of a neural circuit that (in some cases) also includes the hippocampus, and mediates relational information and certain forms of working memory. The possibility that the spatial distribution of the patch and matrix compartments within the caudoputamen underlies these regional differences is discussed.

Unreinforced spatial (latent) learning is mediated by a circuit that includes dorsal entorhinal cortex and fimbria fornix.

The relationship of the entorhinal cortex (EC) and fimbria-fornix (FF) in unreinforced spatial (latent) learning was studied using the conditioned-cue-preference task on an eight-arm radial maze. The maze was turned before every trial to eliminate the use of local cues. During three pre-exposure sessions, food-deprived rats explored the center platform and two adjacent arms of the maze. Since most of the same cues were visible from both arm locations, discriminating them required spatial learning. The rats were then alternately confined to the end of each arm over several days: one arm always contained food, the other was empty. Finally, the rats were allowed free access to both arms with no food present. Normal rats spent more time in their food-paired than in their unpaired arms showing that they learned to discriminate between the arm locations. Bilateral micro-injections of muscimol into the dorsal, but not into the ventral EC, given before the pre-exposure sessions only, impaired the discrimination. The discrimination was also impaired in rats with unilateral lesions of FF and contralateral injections of muscimol into the dorsal EC given before the pre-exposure sessions. Ipsilateral FF lesions and entorhinal inactivation had no effect. These results indicate that the acquisition of information during unreinforced exploration of a novel environment requires an intact circuit involving the dorsal EC and fimbria fornix. Together with previous reports, that this form of learning does not require a functional hippocampus, (Gaskin et al. (2005) Hippocampus 15:1085-1093) the findings also suggest that the acquisition of certain kinds of unreinforced information by this circuit is independent of the hippocampus.