The basolateral amygdaloid complex - its development, morphology and functions

For many years the amygdaloid body hss been an object of numerous investigations on different species, because the basolateral complex, being the main part of the amygdaloid body, is regarded ss "sensory input " to this structure. It plays a very important role in so called emotional memory and learning, what is particularly important in early developmental stages. Impairment at this time may cause psychiatric problems in later life, like neurosis, phobia, unconscious fear or panic attacks. Complicated functions of the basolateral complex equire precise control and modulation especially in early development. In this review the morphological changes during the development and maturation will be discussed and compared with neurotransmitter as well as with the expression of the calcium bindig proteins at various stages of the development

Immunohistochemical study of microglial and astroglial cells during postnatal development of rat striatum

The present study investigates the development of microglial and astroglial cells in the postnatal rat striatum, using immunohistochemical methods with panel antibodies that recognize macrophage antigens of unknown function - ED l, complement type 3 receptor- OX-42 (for microglia) and glial fibrillary acidic protein (for astrocytes). On the day of birth, EDl/OX-42- immunoreactive microglial cells present in the striatum represent ameboid microglia. Between PO and P10 we could observe the migration of ameboid microglial cells from neuroepithelial ventricular zone through internal and external capsules into the striatum. During the second postnatal week (PIO, P14) a considerable decline of ameboid EDl-immunoreactive microglial cells and an increase of the number of OX-42 positive ramified cells were observed. At P21 only OX-42 positive ramified cells were observed in the whole striatum. On the day of birth, only a few GFAP positive cells resembling radial glia were observed in the striatium. During the first postnatal week, the number of GFAP-positive cells increased significantly; they showed typical morphology of the astrocytes present in the adult animals. After P22 the final striatal population of astroglia was formed

Postnatal development of the basolateral complex of rabbit amygdala: a stereological and histochemical study

The aim of the study was to estimate developmental changes in the rabbit basolateral complex (BLC) by stereological and histochemical methods. Material consisted of 45 brains of New Zealand rabbits (aged from 2 to 180 days, P2 to P180) of both sexes, divided into nine groups. The following parameters were estimated: volume of the cerebral hemisphere; volume of the whole BLC and of particular BLC nuclei; neuronal density and total number of neurons in these nuclei. Developmental changes in acetylcholinesterase (AChE) activity in the BLC were also examined. The volume of the cerebral hemisphere increased until P30, whereas volumes of nuclei increased for longer – until P90. The density of neurons in all nuclei studied reached the level characteristic for an adult animal at about P30. The total number of neurons in the dorsolateral division of the lateral nucleus (Ldl) stabilized the earliest – between P30 and P60, whereas in the ventromedial division of the lateral nucleus (Lvm), basomedial (BM) and basolateral (BL) nuclei the number stabilized later – between P60 and P90. AChE activity appears minimal in the BLC on P2, reaches a maximum on P30 and then decreases to the level characteristic of an adult animal on P60. AChE activity was greater in BL than in other nuclei in all age groups. Reaching adult AChE activity 1 month earlier than the total number of neurons in the BLC may indicate a role of the cholinergic system in BLC maturation

Brain anatomy of the 4‐day‐old European rabbit

International audienceThe European rabbit (Oryctolagus cuniculus) is a widely used model in fundamental, medical and veterinary neurosciences. Besides investigations in adults, rabbit pups are relevant to study perinatal neurodevelopment and early behaviour. To date, the rabbit is also the only species in which a pheromone - the mammary pheromone (MP) - emitted by lactating females and active on neonatal adaptation has been described. The MP is crucial since it contributes directly to nipple localisation and oral seizing in neonates, i.e. to their sucking success. It may also be one of the non-photic cues arising from the mother, which stimulates synchronisation of the circadian system during pre-visual developmental stages. Finally, the MP promotes neonatal odour associative and appetitive conditioning in a remarkably rapid and efficient way. For these different reasons, the rabbit offers a currently unique opportunity to determine pheromonal-induced brain processing supporting adaptation early in life. Therefore, it is of interest to create a reference work of the newborn rabbit pup brain, which may constitute a tool for future multi-disciplinary and multi-approach research in this model, and allow comparisons related to the neuroethological basis of social and feeding behaviour among newborns of various species. Here, in line with existing experimental studies, and based on original observations, we propose a functional anatomical description of brain sections in 4-day-old rabbits with a particular focus on seven brain regions which appear important for neonatal perception of sensory signals emitted by the mother, circadian adaptation to the short and single daily nursing of the mother in the nest, and expression of specific motor actions involved in nipple localisation and milk intake. These brain regions involve olfactory circuits, limbic-related areas important in reward, motivation, learning and memory formation, homeostatic areas engaged in food anticipation, and regions implicated in circadian rhythm and arousal, as well as in motricity

Brain processing of a configural vs elemental odor mixture in the newborn rabbit

Organisms are surrounded throughout life by chemically complex odors. How individuals process an odorant within a mixture or a mixture as a whole is a key question in neuroethology and chemical senses. This question is addressed here by using newborn rabbits, which can be rapidly conditioned to a new stimulus by single association with the mammary pheromone. After conditioning to ethyl maltol (odorant B), pups behaviorally respond to B and an A'B' mixture (68/32 ratio) but not to ethyl isobutyrate (odorant A) or an AB mixture (30/70 ratio). This suggests elemental and configural perception of A'B' and AB, respectively. We then explored the neural substrates underlying the processing of these mixtures with the hypothesis that processing varies according to perception. Pups were pseudoconditioned or conditioned to B on postnatal day 3 before exposure to B, A'B' or AB on day 4. Fos expression was not similar between groups (mainly in the olfactory bulb and posterior piriform cortex) suggesting a differential processing of the stimuli that might reflect either stimulus complexity or conditioning effect. Thus, the ratio of components in A'B' vs AB leads to differential activation of the olfactory system which may contribute to elemental and configural percepts of these mixtures. In addition, together with recent behavioral data, this highlights that configural perception occurs even in relatively immature animals, emphasizing the value of the newborn rabbit for exploration of odor mixture processing from molecules to brain and behavior

Very Early Development of Nucleus Taeniae of the Amygdala

Ikebuchi M, Nanbu S, Okanoya K, Suzuki R, Bischof H-J. Very Early Development of Nucleus Taeniae of the Amygdala. Brain Behavior And Evolution. 2013;81(1):12-26.The avian nucleus taeniae of the amygdala (TnA) corresponds to part of the mammalian medial amygdala. Like its mammalian counterpart, it has been shown to be involved in the control of social function. According to behavioral observations, such control is already necessary early in the ontogenetic development of a bird. If so, TnA should be one of the earliest differentiating brain structures of the telencephalon. Our anatomical study shows that TnA can already be delineated at posthatching day one. The volume of TnA exhibits a growth spurt between days 1 and 8 posthatch, developing at a faster rate than the entire telencephalon. Our results suggest that between days 1 and 8 the growth of neuropil exceeds the enhancement of neuron number (leading to a decrease of cell density), and an addition at the same pace of new neurons and neuropil thereafter. A plateau is reached at posthatch day 30. The development of TnA precedes that of the song control nuclei and is similar to the early growth of thalamic and telencephalic sensory areas. This adds to the idea that this structure may already be involved in social control at the time of hatching. A proximate cause of the early development of TnA might be the direct afference from the olfactory bulb. Copyright (C) 2012 S. Karger AG, Base