Hamburg  - The brains of babies raised without fathers may be "wired" differently than those of babies raised by both parents, according to findings by German scientists working with rodents.

Fatherless rodent babies exhibit significantly different neuronal growth patterns than do their peers raised with fathers. Their behaviour is much more aggressive and anti-social as well, according to the findings, published in the journal Developmental Neurology.

"Similar to maternal care, paternal care is a source of neonatal sensory stimulation, which in primates and rodents has been shown to be essential for developing structure and function of sensory cortices," writes Dr Katharina Braun who headed the research team at the department of zoology and developmental neurobiology at Otto von Guericke University in Magdeburg, Germany.

The studies involved tests on a chinchilla-like rodent called Octodon degus, which has brain circuitry similar to that of primates.

"The aim of our study in the biparental rodent Octodon degus was to assess the impact of paternal deprivation on dendritic and synaptic development in the somatosensory cortex," Dr Braun writes in the report.

Noting that this breed of rodents share duties in raising offspring, she says the goal of her researchers was to determine the effect of single-parent rearing, in particular, rearing by only the mother without a father. The scientists compared not only behaviour but also the brain structures of the single-mother offspring.

"We quantified the amount of paternal care in relation to total parental investment and compared dendritic and synaptic development of pyramidal neurons in the somatosensory cortex of animals raised by a single mother or by both parents," she writes.

"On the behavioural level we show that paternal care comprises 37 per cent of total parent-offspring interactions and that the somatosensory stimulation provided by the fathers primarily consists of huddling, licking/grooming, and playing."

Rodent babies who were deprived of fatherly child-care exhibited more aggressive behaviour. Not only were they outwardly socially dysfunctional, their brains also exhibited different neurological synapses.

"On the morphological level we found that, compared with offspring raised by both parents (mother and father), the father-deprived animals displayed significantly reduced spine numbers on the basal dendrites of pyramidal neurons," the report says.

"Furthermore, paternal deprivation induces hemispheric asymmetry of the dendritic morphology of somatosensory pyramidal neurons. Father-deprived animals show shorter and less complex basal dendrites in the left somatosensory cortex compared with the right hemisphere," it adds.

"These findings indicate that paternal deprivation results in delayed or retarded dendritic and synaptic development of somatosensory circuits," Dr Braun writes. (dpa)