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Neither the SCN nor the adrenals are required for circadian time-place learning in mice.

Mulder CK, Papantoniou C, Gerkema MP, Van Der Zee EA - Chronobiol. Int. (2014)

Bottom Line: During Time-Place Learning (TPL), animals link biological significant events (e.g. encountering predators, food, mates) with the location and time of occurrence in the environment.Abrupt FEO phase-shifts (induced by advancing and delaying feeding time) affected TPL performance in specific test sessions while a LEO phase-shift (induced by a light pulse) more severely affected TPL performance in all three daily test sessions.We conclude that, although cTPL is sensitive to timing manipulations with light as well as food, neither the SCN nor the adrenals are required for cTPL in mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Neurobiology and.

ABSTRACT
During Time-Place Learning (TPL), animals link biological significant events (e.g. encountering predators, food, mates) with the location and time of occurrence in the environment. This allows animals to anticipate which locations to visit or avoid based on previous experience and knowledge of the current time of day. The TPL task applied in this study consists of three daily sessions in a three-arm maze, with a food reward at the end of each arm. During each session, mice should avoid one specific arm to avoid a foot-shock. We previously demonstrated that, rather than using external cue-based strategies, mice use an internal clock (circadian strategy) for TPL, referred to as circadian TPL (cTPL). It is unknown in which brain region(s) or peripheral organ(s) the consulted clock underlying cTPL resides. Three candidates were examined in this study: (a) the suprachiasmatic nucleus (SCN), a light entrainable oscillator (LEO) and considered the master circadian clock in the brain, (b) the food entrainable oscillator (FEO), entrained by restricted food availability, and (c) the adrenal glands, harboring an important peripheral oscillator. cTPL performance should be affected if the underlying oscillator system is abruptly phase-shifted. Therefore, we first investigated cTPL sensitivity to abrupt light and food shifts. Next we investigated cTPL in SCN-lesioned- and adrenalectomized mice. Abrupt FEO phase-shifts (induced by advancing and delaying feeding time) affected TPL performance in specific test sessions while a LEO phase-shift (induced by a light pulse) more severely affected TPL performance in all three daily test sessions. SCN-lesioned mice showed no TPL deficiencies compared to SHAM-lesioned mice. Moreover, both SHAM- and SCN-lesioned mice showed unaffected cTPL performance when re-tested after bilateral adrenalectomy. We conclude that, although cTPL is sensitive to timing manipulations with light as well as food, neither the SCN nor the adrenals are required for cTPL in mice.

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Spontaneous alternation (SA) results of homecage control mice (HCC, n = 13), SHAM-lesioned mice (SHAM, n = 8), SCN-lesioned mice (SCNx, n = 10) (pooled data from both batches), or mice from the second batch after adrenalectomy (ADX, n = 7). No statistical differences were found between any of the groups. Error bars represent SEM.
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f4: Spontaneous alternation (SA) results of homecage control mice (HCC, n = 13), SHAM-lesioned mice (SHAM, n = 8), SCN-lesioned mice (SCNx, n = 10) (pooled data from both batches), or mice from the second batch after adrenalectomy (ADX, n = 7). No statistical differences were found between any of the groups. Error bars represent SEM.

Mentions: Prior to each TPL test, a SA test was performed. The SA test is a behavioral paradigm to investigate short-term spatial working memory (by assessing alternation percentage, i.e. SA performance) and general exploration behavior (by assessing the number of entries). Results are shown in Figure 4. We found no differences in SA performance between homecage control mice (HCC, n = 13), SHAM-lesioned mice (SHAM, n = 8), SCN-lesioned mice (SCNx, n = 10) (pooled data from both batches), or mice from the second batch after adrenalectomy (ADX, n = 7; SHAM and SCNx mice from the ADX group were statistically tested as separate groups): One-way ANOVA: F = 1.14, dF = 4, p = 0.36. Bonferroni posttests showed no significant differences between groups (p ≥ 0.1 for all group comparisons). Also, we found no differences in the number of entries between the groups: One-way ANOVA: F = 0.83, dF = 4, p = 0.52. Bonferroni posttests showed no significant differences between groups (p ≥ 0.1 for all group comparisons).Figure 4.


Neither the SCN nor the adrenals are required for circadian time-place learning in mice.

Mulder CK, Papantoniou C, Gerkema MP, Van Der Zee EA - Chronobiol. Int. (2014)

Spontaneous alternation (SA) results of homecage control mice (HCC, n = 13), SHAM-lesioned mice (SHAM, n = 8), SCN-lesioned mice (SCNx, n = 10) (pooled data from both batches), or mice from the second batch after adrenalectomy (ADX, n = 7). No statistical differences were found between any of the groups. Error bars represent SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219850&req=5

f4: Spontaneous alternation (SA) results of homecage control mice (HCC, n = 13), SHAM-lesioned mice (SHAM, n = 8), SCN-lesioned mice (SCNx, n = 10) (pooled data from both batches), or mice from the second batch after adrenalectomy (ADX, n = 7). No statistical differences were found between any of the groups. Error bars represent SEM.
Mentions: Prior to each TPL test, a SA test was performed. The SA test is a behavioral paradigm to investigate short-term spatial working memory (by assessing alternation percentage, i.e. SA performance) and general exploration behavior (by assessing the number of entries). Results are shown in Figure 4. We found no differences in SA performance between homecage control mice (HCC, n = 13), SHAM-lesioned mice (SHAM, n = 8), SCN-lesioned mice (SCNx, n = 10) (pooled data from both batches), or mice from the second batch after adrenalectomy (ADX, n = 7; SHAM and SCNx mice from the ADX group were statistically tested as separate groups): One-way ANOVA: F = 1.14, dF = 4, p = 0.36. Bonferroni posttests showed no significant differences between groups (p ≥ 0.1 for all group comparisons). Also, we found no differences in the number of entries between the groups: One-way ANOVA: F = 0.83, dF = 4, p = 0.52. Bonferroni posttests showed no significant differences between groups (p ≥ 0.1 for all group comparisons).Figure 4.

Bottom Line: During Time-Place Learning (TPL), animals link biological significant events (e.g. encountering predators, food, mates) with the location and time of occurrence in the environment.Abrupt FEO phase-shifts (induced by advancing and delaying feeding time) affected TPL performance in specific test sessions while a LEO phase-shift (induced by a light pulse) more severely affected TPL performance in all three daily test sessions.We conclude that, although cTPL is sensitive to timing manipulations with light as well as food, neither the SCN nor the adrenals are required for cTPL in mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Neurobiology and.

ABSTRACT
During Time-Place Learning (TPL), animals link biological significant events (e.g. encountering predators, food, mates) with the location and time of occurrence in the environment. This allows animals to anticipate which locations to visit or avoid based on previous experience and knowledge of the current time of day. The TPL task applied in this study consists of three daily sessions in a three-arm maze, with a food reward at the end of each arm. During each session, mice should avoid one specific arm to avoid a foot-shock. We previously demonstrated that, rather than using external cue-based strategies, mice use an internal clock (circadian strategy) for TPL, referred to as circadian TPL (cTPL). It is unknown in which brain region(s) or peripheral organ(s) the consulted clock underlying cTPL resides. Three candidates were examined in this study: (a) the suprachiasmatic nucleus (SCN), a light entrainable oscillator (LEO) and considered the master circadian clock in the brain, (b) the food entrainable oscillator (FEO), entrained by restricted food availability, and (c) the adrenal glands, harboring an important peripheral oscillator. cTPL performance should be affected if the underlying oscillator system is abruptly phase-shifted. Therefore, we first investigated cTPL sensitivity to abrupt light and food shifts. Next we investigated cTPL in SCN-lesioned- and adrenalectomized mice. Abrupt FEO phase-shifts (induced by advancing and delaying feeding time) affected TPL performance in specific test sessions while a LEO phase-shift (induced by a light pulse) more severely affected TPL performance in all three daily test sessions. SCN-lesioned mice showed no TPL deficiencies compared to SHAM-lesioned mice. Moreover, both SHAM- and SCN-lesioned mice showed unaffected cTPL performance when re-tested after bilateral adrenalectomy. We conclude that, although cTPL is sensitive to timing manipulations with light as well as food, neither the SCN nor the adrenals are required for cTPL in mice.

Show MeSH
Related in: MedlinePlus