Neonatal frontal lesions in hamsters impair species-typical behaviors and reduce brain weight and neocortical thickness.

Abstract

Syrian golden hamsters with removals of the medial or ventral subfields of the frontal cortex at 4 days of age were compared behaviorally and neuroanatomically with hamsters with similar removals in adulthood. The behavioral results showed that hamsters with neonatal lesions show little sparing of species-typical behaviors such as hoarding and nest building. Study of the development of animals with early lesions showed that although as young juveniles the operated hamsters did not appear to be different from their littermate controls, as they developed they failed to improve in their performance as their littermates did. As adults these early operates were thus severely impaired relative to their littermates. Nonetheless, under certain environmental conditions it was possible to show that the animals were capable of performing the behaviors nearly as proficiently as normal animals. Thus, in order to thoroughly assess the extent of behavioral sparing following early neonatal lesions, it is necessary to test animals under widely varying stimulus conditions. Finally, when the brains of neonatally operated hamsters were compared with those of animals operated on in adulthood, there were striking differences; although the area of cavity appeared smaller in the neonatal operates, their brains weighed less and the remaining neocortex was thinner.

Traumatic Injury to the Immature Frontal Lobe: A New Murine Model of Long-Term Motor Impairment in the Absence of Psychosocial or Cognitive Deficits

“…In line with several previous studies reporting the emergence of injury-induced impairments over the course of brain development [16,30,31], we saw an age-dependent emergence of rearing deficits, which were absent at adolescence but pronounced in adult brain-injured mice. We also uncovered a distinct effect of age on normal behavioral phenotypes, independent of injury.…”

“…Functional outcomes were assessed at adolescence and early adulthood, based upon previous studies in both rodents and monkeys demonstrating that significant impairments may not emerge until later in life [16,30,31]. Here we find cortical damage and overt tissue loss in the M1, M2 and supplementary motor cortex, regions which are essential for the planning, coordination and execution of movements [32].…”

Longitudinal measures of cognition in the Ts65Dn mouse: Refining windows and defining modalities for therapeutic intervention in Down syndrome

“…Indeed, as with infants with DS, Ts65Dn mice eventually reach developmental milestones but do so later than euploids. Interestingly, we found a strong correlation between the developmental milestone score for each animal and its ability to build a nest at 2 month of age, a species-typical behavior that has been related to attentional processes and frontal cortical function (Kolb and Whishaw, 1985; de Brabander et al, 1991). We have also uncovered a moderate correlation between developmental milestone score and cognitive performance, consistent with previous mouse studies which show the importance of early development on subsequent social and cognitive skills (Branchi et al, 2013; Cutuli et al, 2015).…”

Enhanced Phosphatase Activity Attenuates α-Synucleinopathy in a Mouse Model

“…Although nesting behavior has been used to assess nigrostriatal sensorimotor function in rodents (Szczypka et al, 2001; Deacon, 2006), the α-Syn Tg mice used in the present study are significantly impaired with respect to this complex behavior, as has been described previously (Fleming et al, 2004), despite lack of appreciable dopaminergic deficits by 9 months of age. This behavioral impairment has been attributed to a decline in fine motor skills or reduction in the shredding urge (Fleming et al, 2004), perhaps due to cortical dysfunction related to high levels of α-Syn expression (Kolb and Whishaw, 1985; Rockenstein et al, 2002). …”