Exercise increases hippocampal neurogenesis to high levels but does not improve spatial learning in mice bred for increased voluntary wheel running.

The hippocampus is important for the acquisition of new memories. It is also one of the few regions in the adult mammalian brain that can generate new nerve cells. The authors tested the hypothesis that voluntary exercise increases neurogenesis and enhances spatial learning in mice selectively bred for high levels of wheel running (S mice). Female S mice and outbred control (C) mice were housed with and without running wheels for 40 days. 5-Bromodeoxyuridine was used to label dividing cells. The Morris water maze was used to measure spatial learning. C runners showed a strong positive correlation between running distance and new cell number, as well as improved learning. In S runners, neurogenesis increased to high levels that reached a plateau, but no improvement in learning occurred. This is the first evidence that neurogenesis can occur without learning enhancement. The authors propose an alternative function of neurogenesis in the control of motor behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Patterns of Brain Activity Associated With Variation in Voluntary Wheel-Running Behavior.

Rodents spontaneously run on wheels, but what underlies variation within and between species is unknown. This study used Fos immunoreactivity to compare brain activity in mice selectively bred for high wheel running (S) versus control (C) mice. Mice ran for 6 days, but on Day 7, half the mice were prevented from running. A strong positive correlation was found between running distance and Fos in the dentate gyrus of C runners that was lost in S runners. In mice prevented from running, Fos was higher in S than in C in the lateral hypothalamus, medial frontal cortex, and striatum. Results implicate specific brain regions in motivation to run and others in control of the intensity of the locomotor behavior itself. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exercise improves memory acquisition and retrieval in the Y-maze task: Relationship with hippocampal neurogenesis.

Enhanced physical activity is associated with improvements in cognitive function in rodents as well as in humans. The authors examined in detail which aspects of learning and memory are influenced by exercise, using a spatial Y-maze test combined with a 14-day exercise paradigm at different stages of learning. The authors show that 14 days of wheel running promotes memory acquisition, memory retention, and reversal learning. The exercise paradigm that was employed also significantly increased the number of maturing neurons, suggesting that an increase in neurogenesis underlies the positive effects of exercise on Y-maze performance. Finally, the authors show that memory acquisition in itself does not have a major impact on the number of immature neurons. However, memory retention testing and reversal learning both cause a significant reduction in the number of doublecortin and Ser133- phosphorylated pCREB-positive cells, indicating that a decrease in neurogenesis might be a prerequisite for optimal memory retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Voluntary exercise influences behavioral development in rats exposed to alcohol during the neonatal brain growth spurt.

Children exposed to alcohol prenatally may suffer from severe brain damage, expressed as a variety of behavioral problems, including hyperactivity and learning deficits. There is a critical need to identify effective treatments for fetal alcohol effects. Physical exercise enhances cognitive ability and increases neurogenesis in the hippocampus, a brain area important for learning and memory. Thus, the present study examined whether physical exercise might reduce the severity of alcohol-induced behavioral alterations. Sprague-Dawley rats were intubated with 5.25 g/kg/day ethanol during the third trimester equivalent (postnatal days [PDs] 4-9). Intubated sham control and nontreated controls were included. From PD 21 to PD 51, half of the subjects were given access to running wheels. On PD 52, subjects were tested on the Morris water maze, and on PD 60, open field activity levels were measured. Morris maze performance was significantly impaired among ethanol-exposed subjects; exercise significantly improved performance of all groups. Similarly, ethanol-exposed subjects were overactive in the open field, an effect attenuated with exercise. In sum, these data suggest that exercise may increase neuronal plasticity not only in controls, but also in subjects exposed to alcohol during development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Single enrichment variables differentially reduce age-related memory decline in female mice.

The authors sought to determine how different elements of enrichment, for example, cognitive stimulation and voluntary exercise, differ in their ability to improve memory throughout the lifespan. Young, middle-aged, and aged female C57BL/6 mice received 24-hr exposure in their home cages to toys alone (cognitive stimulation), running wheels alone (exercise), or both toys and running wheels (complex enrichment) for 4 weeks prior to and then throughout spatial water maze testing. As expected, spatial memory became progressively worse with age. Exercise alone improved spatial water maze performance in young mice, whereas both exercise alone and complex enrichment improved spatial maze performance in middle-aged mice. All enrichment treatments improved spatial maze performance in aged mice. These data suggest that exercise is the most effective element of enrichment in young female mice and that both cognitive stimulation and exercise are necessary to reliably improve spatial water maze performance in aging female mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Espresso Reward Learning, Hold the Dopamine: Theoretical Comment on Robinson et al. (2005).

Question: Is dopamine needed for reward learning? Answer: No--at least, not in the brain of a caffeinated dopamine-deficient (DD) mutant mouse. That is the conclusion of an important paper in this issue by S. Robinson, S. M. Sandstrom, V. H. Denenberg, and R. D. Palmiter (see record 2005-01705-001). Those authors demonstrate that reward learning can proceed normally in the brains of DD mice, even though they contain no dopamine at the time of learning, if the mice are given caffeine just before learning. Caffeine activates the DD mice by a nondopaminergic mechanism, allowing them to learn where to obtain food reward in a T-maze runway. Their reward-learning-without-dopamine is revealed on a subsequent test day, when dopamine function is restored by L-dopa administration. Robinson et al. conclude that dopamine is not needed for normal learning about rewards, or for hedonic "liking" of rewards during learning, but rather specifically for a motivational "wanting" component of reward, such as incentive salience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confucian and Socratic learning.

Replies to the comments by R. A. R. Gurung (see record 2003-03405-011) and J. Li (see record 2003-03405-012) regarding comments on the article by R. G. Tweed and D. R. Lehman (2001) which stated that a Confucian-Socratic framework provides a structure for analyzing culture-influenced aspects of academic learning. In this article, Tweed and Lehman argued that these ancient exemplars model approaches to learning continue to differentiate students within a modern Canadian postsecondary context. In this reply, Tweed and Lehman advise caution in how Gurung placed their Confucian-Socratic framework within the context of prior theory on education and epistemological development because these models were developed exclusively in the West. Furthermore, Tweed and Lehman believe that Li's argument misinterpreted their article, and that they should of consistently used the term "personal reform" rather than "behavioral reform" in order to communicate the depth of personal change envisioned by Confucius. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Understanding and using the Implicit Association Test: I. An improved scoring algorithm": Correction to Greenwald et al. (2003).

Reports an error in "Understanding and using the Implicit Association Test: I. An improved scoring algorithm" by Anthony G. Greenwald, Brian A. Nosek and Mahzarin R. Banaji (Journal of Personality and Social Psychology, 2003[Aug], Vol 85[2], 197-216). The article contained several errors. On page 203, the data lines in Figure 2 are incorrectly labeled. As in Figure 1, the line with filled squares as data points should be labeled MEAN, the line with filled diamonds as data points should be labeled MEDIAN, and the line with unfilled squares as data points should be labeled RECIPROCAL. (The following abstract of the original article appeared in record 2003-05897-003.) In reporting Implicit Association Test (IAT) results, researchers have most often used scoring conventions described in the first publication of the IAT (A. G. Greenwald, D. E. McGhee, & J. L. K. Schwartz, 1998). Demonstration IATs available on the Internet have produced large data sets that were used in the current article to evaluate alternative scoring procedures. Candidate new algorithms were examined in terms of their (a) correlations with parallel self-report measures, (b) resistance to an artifact associated with speed of responding, (c) internal consistency, (d) sensitivity to known influences on IAT measures, and (e) resistance to known procedural influences. The best-performing measure incorporates data from the IAT's practice trials, uses a metric that is calibrated by each respondent's latency variability, and includes a latency penalty for errors. This new algorithm strongly outperforms the earlier (conventional) procedure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The inflammatory response system and the availability of plasma tryptophan in patients with primary sleep disorders and major depression

Food restriction increases maximal life span in rodents. Male rats that exercise in voluntary running wheels do not have an increase in maximal longevity despite a relative caloric deficit. In contrast, sedentary rats that are food restricted so as to cause the same caloric deficit have an extension of maximal longevity. It seemed possible that exercise-induced oxidative stress might prevent a maximum life span-extending effect of a caloric deficit to manifest itself. This study was done to determine if antioxidants would allow a maximal longevity-extending effect of exercise to manifest itself in male rats. The antioxidant diet had no effect on longevity of the runners (Antiox., 951 +/- 158 days versus control 937 + 171 days), or of the sedentary controls (875 +/- 127 versus 858 +/- 152 days). As in previous studies, wheel running modestly increased average longevity (approximately 9%), but had no effect on maximal life span. The finding that antioxidants had no effect on longevity of the wheel runners supports the interpretation that the caloric deficit induced by exercise in male rats does not have a life-extending effect that is countered by oxidative tissue damage.     

Morris Water Maze Learning in Two Rat Strains Increases the Expression of the Polysialylated Form of the Neural Cell Adhesion Molecule in the Dentate Gyrus But Has No Effect on Hippocampal Neurogenesis.

In the current study, the authors investigated whether Morris water maze learning induces alterations in hippocampal neurogenesis or neural cell adhesion molecule (NCAM) polysialylation in the dentate gyrus. Two frequently used rat strains, Wistar and Sprague-Dawley, were trained in the spatial or the nonspatial version of the water maze. Both training paradigms did not have an effect on survival of newly formed cells that were labeled 7-9 days prior to the training or on progenitor proliferation in the subgranular zone. However, the granule cell layer of the spatially trained rats contained significantly more positive cells of the polysialylated form of the NCAM. These data demonstrate that Morris water maze learning causes plastic change in the dentate gyrus without affecting hippocampal neurogenesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unpacking the cognitive map: The parallel map theory of hippocampal function.

In the parallel map theory, the hippocampus encodes space with 2 mapping systems. The bearing map is constructed primarily in the dentate gyrus from directional cues such as stimulus gradients. The sketch map is constructed within the hippocampus proper from positional cues. The integrated map emerges when data from the bearing and sketch maps are combined. Because the component maps work in parallel, the impairment of one can reveal residual learning by the other. Such parallel function may explain paradoxes of spatial learning, such as learning after partial hippocampal lesions, taxonomic and sex differences in spatial learning, and the function of hippocampal neurogenesis. By integrating evidence from physiology to phylogeny, the parallel map theory offers a unified explanation for hippocampal function. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Endocrine regulation of cognition and neuroplasticity: Our pursuit to unveil the complex interaction between hormones, the brain, and behaviour.

Gonadal and stress hormones modulate neuroplasticity and behaviour. This review focuses on our findings over the past decade on the effects of estrogens and androgens on hippocampal neurogenesis, hippocampus-dependent learning and memory and the effects of reproductive experience in the rodent. Evidence suggests that acute estradiol initially enhances and subsequently suppresses cell proliferation in the dentate gyrus of adult female rodents. Repeated exposure to estradiol modulates hippocampal neurogenesis and cell death in adult female, but not male, rodents while, testosterone and dihydrotestosterone upregulate hippocampal neurogenesis in adult male rodents. Estradiol dose-dependently affects different brain regions involved in working memory (prefrontal cortex, hippocampus), reference memory (hippocampus) and conditioned place preference (amygdala). Pregnancy and motherhood differentially regulate adult hippocampal neurogenesis and spatial working memory in the dam after weaning. These studies and others demonstrate that the female brain responds to steroid hormones differently than the male brain. It is of the upmost importance to investigate the effects on neuroplasticity and behaviour in both the male and the female, particularly when modelling diseases that exhibit sex differences in incidence, etiology or treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial and nonspatial learning in mice: effects of S100 beta overexpression and age

S100 beta, a Ca2+ binding astrocytic brain protein implicated in brain development and neurophysiology, has elevated levels in progressive neurodegenerative diseases, Down's Syndrome, and Alzheimer Disease. Transgenic mice carrying multiple S100 beta gene copies exhibited abnormal exploratory behaviors and synaptic processes suggesting hippocampal dysfunction. Here we analyze learning in a hippocampal-dependent (spatial) as well as a non-hippocampal-dependent (nonspatial) version of the Morris water maze and compare CD1 control and CD1-derived S100 beta transgenic mice. We also investigate possible progressive age-dependent effects of S100 beta overexpression by comparing two age groups of the above mice: 3- and 16-month-old. We show that 3-month-old S100 beta transgenic mice have a spatial task-specific impairment confirming a hippocampal dysfunction. However, we found the 16-month-old transgenic mice statistically indistinguishable from their normal counterparts, a result that does not confirm progressive S100 beta transgene effects. We also show that age, independently of the transgene, impairs spatial learning, spares nonspatial learning and reference memory, but leads to behavioral rigidity.     

"Ovarian hormones and cognition in the aged female rat: I. Long-term, but not short-term, ovariectomy enhances spatial performance": Correction to Bimonte-Nelson et al. (2003).

Reports an error in "Ovarian Hormones and Cognition in the Aged Female Rat: I. Long-Term, but Not Short-Term, Ovariectomy Enhances Spatial Performance" by Heather A. Bimonte-Nelson, Rachel S. Singleton, Christopher L. Hunter, Kimber L. Price, Alfred B. Moore and Ann-Charlotte E. Granholm (Behavioral Neuroscience, 2003[Dec], Vol 117[6], 1395-1406). The fifth sentence of the abstract reads, "Aged rats exhibited estradiol and elevated progesterone levels comparable to those of young rats." The sentence should read as follows: "Aged rats exhibited similar estradiol and elevated progesterone levels compared with those of young rats." (The following abstract of the original article appeared in record 2003-10460-025.) Although research suggests that ovariectomy (ovx) is detrimental to spatial cognition in young rats, little work has evaluated the cognitive effects of ovx in aged rats. The authors investigated the effects of ovx in aged rats using the water radial-arm maze. In Study 1, young rats and aged rats receiving ovx 1.5 months before testing outperformed aged rats receiving sham surgery or ovx 21 days before testing. In Study 2, young rats and aged rats receiving ovx 2.0 or 6.0 months before testing outperformed aged sham rats. Aged rats exhibited estradiol and elevated progesterone levels comparable to those of young rats. The findings suggest that 1.5-6.0 months, but not 21 days, of ovx improves spatial memory in aged rats. The hypothesis that long-term ovarian hormone loss is detrimental to spatial memory in aged rats was not supported. The authors hypothesize that removal of elevated progesterone levels is related to the ovx-induced cognitive enhancement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Running intensity as determined by heart rate is the same in fast and slow runners in both the 10- and 21-km races

The aims of this study were to determine (1) whether running speed is directly proportional to heart rate (HR) during field testing and during 10- and 21-km races, and (2) whether running intensity, as estimated from HR measurements, differs in 10- and 21-km races and between slow and fast runners at those running distances. Male runners were divided into a fast (65-80 min for 21 km; n = 8) or slow (85-110 min for 21 km; n = 8) group. They then competed in 10- and 21-km races while wearing HR monitors. All subjects also ran in a field test in which HR was measured while they ran at predetermined speeds. The 10-km time was significantly less in the fast compared with the slow group (33:15 +/- 1:42 vs 40:07 +/- 3:01 min:s; mean +/- S.D.), as was 21-km time (74:19 +/- 4:30 vs 94:13 +/- 9:54 min:s) (P < 0.01). Despite the differences in running speed, the average running intensity (%HRmax) for the fast and slow groups in the 10-km race was 90 +/- 1 vs 89 +/- 3% and in the 21-km race 91 +/- 1 vs 89 +/- 2%, respectively. In addition, %HRmax was consistently lower in the field test at the comparative average running speeds sustained in the 10-km (P < 0.01) and 21-km (P < 0.001) races. Hence, factors in addition to work rate or running speed influence the HR response during competitive racing. This finding must be considered when running intensity for competitive events is prescribed on the basis of field testing performed under non-competitive conditions in fast and slow runners.     

Dynamics of step length adjustment during running: A comment on Patla, Robinson, Samways, and Armstrong (1989).

W. H. Warren, D. S. Young, and D. N. Lee (see record 1986-26300-001) found that treadmill runners control step length by regulating vertical impulse, which could be modulated by the optical time-to-contact variable tau. In contrast, Patla, Robinson, Samways, and Armstrong (see record 1990-00234-001) report a 40% contribution of horizontal impulse in overground running and a control strategy that depends on the timing of target cuing, undermining the tau-impulse theory. This discrepancy is due to differences in methodology, analysis, and interpretation. First, the cuing effect is exactly what the tau-impulse theory would predict. Second, new data on the dynamics of overground running show only a 20% contribution of horizontal impulse, which could be a biomechanical consequence of regulating vertical impulse. This is apparently due to important differences between treadmill and overground running. However, the data indicate that runners regulate a global impulse parameter that primarily affects vertical impulse, salvaging the tau-impulse theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Erratum to Satinder.

Reports an error in the article "Arousal Explains Difference in Avoidance Learning of Genetically Selected Rat Strains" by K. Paul Satinder (Journal of Comparative and Physiological Psychology, 1977, Vol. 91, No. 6, pp. 1326-1336), one line was printed incorrectly. On page 1331, the last line of Table 2 reads as follows: RNA/Lu oneway 193 280. The line should be changed to read as follows: RHA/Lu oneway 193 280. (The following abstract originally appeared in record 1978-22592-001) Manipulated task complexity differences in avoidance learning of genetically selected strains of rats under dextroamphetamine (1, 2, and 4 mg/kg, ip). 288 Ss from RHA/Lu, RLA/Lu, RCA/Lu, RHA by RLA, and RLA by RHA strains were studied. With decreasing levels of task complexity the differences in avoidance learning between the selectively bred strains decreased significantly. Under the lower levels of complexity the strains reversed their relative positions in avoidance learning. Results are discussed in terms of inverted--U arousal function. The factors investigated in this study indicate that the differences in avoidance behavior of these lines of rats may be understood as deriving from genetically related different levels of arousal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imagery.

Comments upon Robert R. Holt's paper (see record 1965-00378-001) on imagery. The author agrees with Holt, who demands "the return of the ostracized," and believes that research on the use of visual images in remembering, learning, and thinking should be resumed. The author also calls attention to a three-volume book entitled "Zur Analyse der Ged?chtnist?tigkeit und des Vorstellungsverlaufs" by Georg Elias Müller. The book summarizes knowledge on the psychology of learning, with emphasis on the use of visual aids in learning, and closes with a discussion of the findings of the Würzburg school. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Foerde et al. (2008).

Reports an error in "Selective corticostriatal dysfunction in schizophrenia: Examination of motor and cognitive skill learning" by Karin Foerde, Russell A. Poldrack, Barbara J. Knowlton, Fred W. Sabb, Susan Y. Bookheimer, Robert M. Bilder, Don Guthrie, Eric Granholm, Keith H. Nuechterlein, Stephen R. Marder and Robert F. Asarnow (Neuropsychology, 2008[Jan], Vol 22[1], 100-109). Table 1 on page 102 should have included the BPRS Depression-Anxiety subscale score 9.00 (3.99) under the column heading Schiz pts. Table displays means with standard deviations in parentheses. (The following abstract of the original article appeared in record 2008-00382-011.) [Correction Notice: An erratum for this article was reported in Vol 22(2) of Neuropsychology (see record 2008-02526-002). The DOI for the supplemental materials was printed incorrectly. The correct DOI is as follows: http://dx.doi.org/10.1037/0894-4105.22.1.100.supp.] It has been suggested that patients with schizophrenia have corticostriatal circuit dysfunction (Carlsson & Carlsson, 1990). Skill learning is thought to rely on corticostriatal circuitry and different types of skill learning may be related to separable corticostriatal loops (Grafton, Hazeltine, & Ivry, 1995; Poldrack, Prabhakaran, Seger, & Gabrieli, 1999). The authors examined motor (Serial Reaction Time task, SRT) and cognitive (Probabilistic Classification task, PCT) skill learning in patients with schizophrenia and normal controls. Development of automaticity was examined, using a dual task paradigm, across three training sessions. Patients with schizophrenia were impaired at learning on the PCT compared to controls. Performance gains of controls occurred within the first session, whereas patients only improved gradually and never reached the performance level of controls. In contrast, patients were not impaired at learning on the SRT relative to controls, suggesting that patients with schizophrenia may have dysfunction in a specific corticostriatal subcircuit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Hobfoll et al. (2003).

Reports errors in the original article by S. E. Hobfoll et al (Journal of Personality & Social Psychology, 2003[Mar], Vol 84[3], 632-643). On page 643, in the tables for Appendixes B and C, the variables labeled with "T3" should all read "T2." In Appendix C, the column headings "Nonlinear model" should read "Nonlinear model T1"; the column headings "Linear model" should read "Nonlinear model T2." These changes do not affect the findings, interpretations, or conclusions. (The following abstract of this article originally appeared in record 2003-01588-018): The authors examined a dynamic conceptualization of stress by investigating how economic stress, measured in terms of material loss, alters women's personal and social resources and how these changed resources impact anger and depressive mood. Resource change in women's mastery and social support over 9 months was significantly associated with changes in depressive mood and anger among 714 inner city women. Greater loss of mastery and social support was associated with increased depressive mood and anger. Loss of mastery and social support also mediated the impact of material loss on depressive mood and anger. Resource loss and worsening economic circumstances had more negative impact than resource gain... (PsycINFO Database Record (c) 2010 APA, all rights reserved)