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Hidden Markov model analysis of maternal behavior patterns in inbred and reciprocal hybrid mice.

Carola V, Mirabeau O, Gross CT - PLoS ONE (2011)

Bottom Line: Individual variation in maternal care in mammals shows a significant heritable component, with the maternal behavior of daughters resembling that of their mothers.For the HMM analysis we defined seven states: arched-backed nursing, blanket nursing, licking/grooming pups, grooming, activity, eating, and sleeping.Differences in these patterns observed in the experimental groups (inbred and hybrid females) were detected only after the application of HMM analysis whereas classical statistical methods and analyses were not able to highlight them.

View Article: PubMed Central - PubMed

Affiliation: Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo, Italy. carola@embl.it

ABSTRACT
Individual variation in maternal care in mammals shows a significant heritable component, with the maternal behavior of daughters resembling that of their mothers. In laboratory mice, genetically distinct inbred strains show stable differences in maternal care during the first postnatal week. Moreover, cross fostering and reciprocal breeding studies demonstrate that differences in maternal care between inbred strains persist in the absence of genetic differences, demonstrating a non-genetic or epigenetic contribution to maternal behavior. In this study we applied a mathematical tool, called hidden Markov model (HMM), to analyze the behavior of female mice in the presence of their young. The frequency of several maternal behaviors in mice has been previously described, including nursing/grooming pups and tending to the nest. However, the ordering, clustering, and transitions between these behaviors have not been systematically described and thus a global description of maternal behavior is lacking. Here we used HMM to describe maternal behavior patterns in two genetically distinct mouse strains, C57BL/6 and BALB/c, and their genetically identical reciprocal hybrid female offspring. HMM analysis is a powerful tool to identify patterns of events that cluster in time and to determine transitions between these clusters, or hidden states. For the HMM analysis we defined seven states: arched-backed nursing, blanket nursing, licking/grooming pups, grooming, activity, eating, and sleeping. By quantifying the frequency, duration, composition, and transition probabilities of these states we were able to describe the pattern of maternal behavior in mouse and identify aspects of these patterns that are under genetic and nongenetic inheritance. Differences in these patterns observed in the experimental groups (inbred and hybrid females) were detected only after the application of HMM analysis whereas classical statistical methods and analyses were not able to highlight them.

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Labeling of observed behavioral sequences by HMM.The HMM formalism takes into account both the frequency and order of a series of observed behaviors to identify and label behavioral states. Examples of HMM state labeling for representative sequences of maternal behavior take from two C57BL/6 mothers (60 observations per hour). Note how bouts of nursing (A and N states) typically start and end with licking and grooming of pups (L). Also, while nursing states (A, N, L) generally last for over ten minutes, activity states (C and E) are much more brief. Observed behaviors: N = blanket nursing, R = rearing, M = moving pups, G = self-grooming in nest, Z = digging, W = sniffing nest, E = eating, D = drinking, A = arched-back nursing, U = sniffing pups, P = licking/grooming pups, S = sniffing cage, B = nest building, and V = self-grooming out of nest; HMM states: C = activity, E = eating, L = grooming pups, G = self-grooming, A = arched-back nursing, N = blanket nursing.
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pone-0014753-g003: Labeling of observed behavioral sequences by HMM.The HMM formalism takes into account both the frequency and order of a series of observed behaviors to identify and label behavioral states. Examples of HMM state labeling for representative sequences of maternal behavior take from two C57BL/6 mothers (60 observations per hour). Note how bouts of nursing (A and N states) typically start and end with licking and grooming of pups (L). Also, while nursing states (A, N, L) generally last for over ten minutes, activity states (C and E) are much more brief. Observed behaviors: N = blanket nursing, R = rearing, M = moving pups, G = self-grooming in nest, Z = digging, W = sniffing nest, E = eating, D = drinking, A = arched-back nursing, U = sniffing pups, P = licking/grooming pups, S = sniffing cage, B = nest building, and V = self-grooming out of nest; HMM states: C = activity, E = eating, L = grooming pups, G = self-grooming, A = arched-back nursing, N = blanket nursing.

Mentions: Initially we examined in detail HMM labelling of maternal behavior in the C57BL/6 strain. For illustration, several representative sequences of maternal behavior are shown with HMM state labelling apposed to observed behavior (Figure 3). Two features were apparent when comparing observed behavior with HMM states. First, HMM states were dominated by one behavior but tolerated occasional diversions to other related behaviors (e.g. self-grooming during EAT, blanket nursing during ABN). Second, a precursory analysis of the sequence of HMM states indicated a stereotypic order, with nursing bouts, for example, composed of relatively persistent stretches of ABN and BLN, and consistently beginning and ending with the LG state. On fewer occasions the GRO state intervened between nest and non-nest behavior.


Hidden Markov model analysis of maternal behavior patterns in inbred and reciprocal hybrid mice.

Carola V, Mirabeau O, Gross CT - PLoS ONE (2011)

Labeling of observed behavioral sequences by HMM.The HMM formalism takes into account both the frequency and order of a series of observed behaviors to identify and label behavioral states. Examples of HMM state labeling for representative sequences of maternal behavior take from two C57BL/6 mothers (60 observations per hour). Note how bouts of nursing (A and N states) typically start and end with licking and grooming of pups (L). Also, while nursing states (A, N, L) generally last for over ten minutes, activity states (C and E) are much more brief. Observed behaviors: N = blanket nursing, R = rearing, M = moving pups, G = self-grooming in nest, Z = digging, W = sniffing nest, E = eating, D = drinking, A = arched-back nursing, U = sniffing pups, P = licking/grooming pups, S = sniffing cage, B = nest building, and V = self-grooming out of nest; HMM states: C = activity, E = eating, L = grooming pups, G = self-grooming, A = arched-back nursing, N = blanket nursing.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3050935&req=5

pone-0014753-g003: Labeling of observed behavioral sequences by HMM.The HMM formalism takes into account both the frequency and order of a series of observed behaviors to identify and label behavioral states. Examples of HMM state labeling for representative sequences of maternal behavior take from two C57BL/6 mothers (60 observations per hour). Note how bouts of nursing (A and N states) typically start and end with licking and grooming of pups (L). Also, while nursing states (A, N, L) generally last for over ten minutes, activity states (C and E) are much more brief. Observed behaviors: N = blanket nursing, R = rearing, M = moving pups, G = self-grooming in nest, Z = digging, W = sniffing nest, E = eating, D = drinking, A = arched-back nursing, U = sniffing pups, P = licking/grooming pups, S = sniffing cage, B = nest building, and V = self-grooming out of nest; HMM states: C = activity, E = eating, L = grooming pups, G = self-grooming, A = arched-back nursing, N = blanket nursing.
Mentions: Initially we examined in detail HMM labelling of maternal behavior in the C57BL/6 strain. For illustration, several representative sequences of maternal behavior are shown with HMM state labelling apposed to observed behavior (Figure 3). Two features were apparent when comparing observed behavior with HMM states. First, HMM states were dominated by one behavior but tolerated occasional diversions to other related behaviors (e.g. self-grooming during EAT, blanket nursing during ABN). Second, a precursory analysis of the sequence of HMM states indicated a stereotypic order, with nursing bouts, for example, composed of relatively persistent stretches of ABN and BLN, and consistently beginning and ending with the LG state. On fewer occasions the GRO state intervened between nest and non-nest behavior.

Bottom Line: Individual variation in maternal care in mammals shows a significant heritable component, with the maternal behavior of daughters resembling that of their mothers.For the HMM analysis we defined seven states: arched-backed nursing, blanket nursing, licking/grooming pups, grooming, activity, eating, and sleeping.Differences in these patterns observed in the experimental groups (inbred and hybrid females) were detected only after the application of HMM analysis whereas classical statistical methods and analyses were not able to highlight them.

View Article: PubMed Central - PubMed

Affiliation: Mouse Biology Unit, European Molecular Biology Laboratory, Monterotondo, Italy. carola@embl.it

ABSTRACT
Individual variation in maternal care in mammals shows a significant heritable component, with the maternal behavior of daughters resembling that of their mothers. In laboratory mice, genetically distinct inbred strains show stable differences in maternal care during the first postnatal week. Moreover, cross fostering and reciprocal breeding studies demonstrate that differences in maternal care between inbred strains persist in the absence of genetic differences, demonstrating a non-genetic or epigenetic contribution to maternal behavior. In this study we applied a mathematical tool, called hidden Markov model (HMM), to analyze the behavior of female mice in the presence of their young. The frequency of several maternal behaviors in mice has been previously described, including nursing/grooming pups and tending to the nest. However, the ordering, clustering, and transitions between these behaviors have not been systematically described and thus a global description of maternal behavior is lacking. Here we used HMM to describe maternal behavior patterns in two genetically distinct mouse strains, C57BL/6 and BALB/c, and their genetically identical reciprocal hybrid female offspring. HMM analysis is a powerful tool to identify patterns of events that cluster in time and to determine transitions between these clusters, or hidden states. For the HMM analysis we defined seven states: arched-backed nursing, blanket nursing, licking/grooming pups, grooming, activity, eating, and sleeping. By quantifying the frequency, duration, composition, and transition probabilities of these states we were able to describe the pattern of maternal behavior in mouse and identify aspects of these patterns that are under genetic and nongenetic inheritance. Differences in these patterns observed in the experimental groups (inbred and hybrid females) were detected only after the application of HMM analysis whereas classical statistical methods and analyses were not able to highlight them.

Show MeSH
Related in: MedlinePlus