Behavioral deficits caused by fetal-alcohol are well expressed in juvenile subjects but usually ameliorate with maturation. It suggests some kind of postnatal regeneration. The aim of the present study was to examine the potential correlation between behavioral recovery and the postnatal hippocampal development in the fetal-alcohol rats. This study included behavioral tests applied to juvenile and adult subjects, unbiased stereology to investigate changes in neuron numbers and hippocampal volumes, the postnatal tracing and analysis of the hippocampal principal neuron&rsquo / s morphology, investigation of age-dependent changes in the distribution of doublecortin-expressing neurons, and evaluation of synaptic development by assessing age-dependent changes in the regional immunoreactivity/expression of synaptophysin and PSD95. Rats have been exposed to ethanol throughout 7-21 gestation days with daily ethanol dose of 6g/kg delivered by intragastric intubation to the pregnant dams. The morphological characteristics were examined on postnatal days P1, P10, P30, P60, in hippocampal CA1, CA3, and DG subregions, in fetal-alcohol and control rats. Both, stereological and doublecortin-immunoreactivity data pointed towards a possibility of limited neurogenesis taking place during a protracted postnatal period not only in the germinal zones (SGZ and SVZ) but also in the hippocampal CA regions. Ethanol effect on postnatal hippocampal development was limited to marginally lower number of granular cells in DG on P30. It correlated with poorer cognitive performance in the fetal-alcohol group. The treatment effect on the morphology of hippocampal neurons was observed mainly in CA region at P1 and seemed to be attributed more to the intubation stress than the ethanol itself.

The prefrontal cortices, in particular lateral prefrontal cortex (LPFC) and anterior cingulate cortex (ACC), have been implicated in top-down control of attention switching and behavioral flexibility. These cortices and their networks are disrupted in autism, a condition in which diverse behaviors such as social communication and attention control are dysregulated. However, little is known about the typical development of these cortical areas or the ways in which this process is altered in neurodevelopmental disorders. In order to identify changes that could affect the local processing of signals transmitted by the short-range pathways connecting the ACC and LPFC I assessed developmental changes in the distinct cortical layers, which send and receive different pathways and have unique inhibitory microenvironments that dictate excitatory-inhibitory balance. Normative developmental trends were compared with those seen in individuals with autism to identify changes that may contribute to symptoms of attention dysfunction. Unbiased quantitative methods were used to study overall neuron density, the density of inhibitory neurons labeled by the calcium-binding proteins calbindin (CB), calretinin (CR), and parvalbumin (PV), and the density, size, and trajectory of myelinated axons in the individual cortical layers in children and adults with and without a diagnosis of autism. There was a reduction in neuron density and an increase in the density of myelinated axons in both areas during neurotypical development. Axons in layers 1-3 of LPFC were disorganized in autism, with increased variability in the trajectory of axons in children and a decrease in the proportion of thin axons in adults. These findings were most significant in layer 1, the ultimate feedback-receiving layer in the cortex. While there were no differences in neuron populations between cohorts in children, in adults with autism there was a significant reduction in the density of CR-expressing neurons in LPFC layers 2-6 and a significant increase in the density of PV-expressing neurons in ACC layers 5-6. In autism, these findings suggest that dysregulation of the normal development of axonal networks, seen in children, may induce compensatory developmental changes in cell and axon populations in adults that could be connected to attention dysregulation. / 2021-10-07T00:00:00Z

Aquesta tesi està centrada en l'estudi dels períodes de regressió i transició. A partir dels treballs de van de Rijt-Plooij & Plooij (1992) sobre els períodes de regressió, l'autor analitza les característiques comportamentals d'aquests períodes i la relació que tenen amb els períodes de transició. Els períodes de regressió s'entenen com uns moments del desenvolupament durant els quals els nens perden la homeostasi del seu organisme i manifesten una sèrie de conductes pertorbadores per a la mare. El matrimoni Plooij manté que els períodes de regressió són la manifestació de les reorganitzacions cerebrals que tenen lloc durant el període postnatal, i constitueixen la base de les noves habilitats que el nen va adquirint. Així, doncs, l'augment de l'atenció que la mare dispensa al nen durant els períodes de regressió esdevé una font estimular imprescindible en els processos d'educació i culturalització de l'infant. Per tant, els períodes de regressió estan íntimament relacionats amb els períodes durant els quals apareixen nous comportaments qualitativament diferents dels anteriors, que es manifesten de forma ràpida i sobtada, permetent una certa sistematització del procés evolutiu, per la qual cosa s'han denominat transicions. Van de Rijt-Plooij & Plooij, i també nosaltres, considerem que els períodes de regressió són índexs dels períodes de transició. Per aquesta raó també s'han denominar reprogressions.Tanmateix, els períodes de regressió es poden convertir en una font de conflictes que, en situació de risc, poden degenerar en maltractament infantil i, fins i tot, esdevenir el germen de possibles patogènies. Com veiem, els conceptes de període de regressió i transició es troben a l'encreuament entre la fisiologia, la psicologia i la psicopatologia del desenvolupament i, el seu estudi establiria un pont interdisciplinar que contribuiria a la construcció d'un model biopsicosocial del desenvolupament.Els objectius del nostre estudi varen ser comprovar si els períodes descrits per van de Rijt-Plooij i Plooij (1992) també els podem observar en un grup de nens de la població catalana sense problemes socio-econòmics o sanitaris aparents. Per altra banda, vàrem voler comprovar si els períodes de regressió tenen relació amb els períodes de transició. El disseny d'investigació correspon a un model longitudinal i transversal. Es varen seguir -mitjançant entrevistes, qüestionaris i observacions- vint diades mare-nen durant catorze mesos, repartides en quatre cohorts de cinc diades cada una d'elles.Partint d'uns criteris establerts a priori per a la categorització dels períodes de regressió i transició, vàrem estudiar la temporalitat d'ambdós tipus de períodes. També s'ha aprofundit sobre les característiques comportamentals i dinàmiques dels períodes de regressió.Respecte les dades, els percentatges màxims dels períodes de regressió del nostre grup d'estudi han aparegut a les setmanes: 5, 8, 12-13, 18, 26-27, 35, 43 i 52. La mitjana setmanal de cada període ha sigut de dues setmanes. Les nostres dades confirmen les obtingudes en la investigació de van de Rijt-Plooij & Plooij. Tanmateix, també hem trobat diferències (els períodes de regressió de l'estudi holandès són més llargs i coincideixen més) que ens suggereixen que la cultura podrien estar actuant en la forma de presentació del períodes de regressió.Pel que fa a la relació entre els períodes de regressió i l'emergència de nous comportaments (períodes de transició), els resultats mostren que les freqüències màximes dels períodes de regressió sempre es troben poques setmanes abans de les freqüències màximes dels períodes de transició. Per tant, és possible que els períodes de regressió siguin indicadors dels períodes de transició. / This thesis focuses on the study of the transitions and regression periods in the infancy. Starting from van de Rijt-Plooij & Plooij's research works about emergence of regression periods in the first years of life, the authors analyse the presence of such periods and your relation with the transition periods.The regression periods can be understood as behavioural signs of brain reorganisations, which the infant experiences in his process of development. This maturing experience would cause a loss of control and of homeostatic regulation in the infants that guarantee the necessary attention and care to the infant's organism during a phase of instability and change. As the author quoted above admits, during regression periods the infant's mind is very sensitive and open to external stimuli, mainly to the socioaffective stimuli proceeding from their mother. But the mother and adults who interact with the infant are not only an important source of affective stimuli. At the same time, they make up the dialogical matrix through which children acquire and share the individual's internal structure to be modified and the psyche development to be oriented towards superior ways of functioning (transitional periods).The basic purpose of our study has been to check whether the regression periods described by van de Rijt-Plooij & Plooij (1992, 1993) appeared in a sample of babies in our country. In addition, whether the ages at which they emerged and their characteristics were likewise comparable to the one found by the author quoted. On the other hand, our intention is to analyse the qualitative changes, which supposedly precede regression periods.The research design corresponds to a transversal and longitudinal model. For this reason, twenty pairs mother-infant were divided into cohorts of five months each in the follow way: 1 cohort (3-20 weeks), 2 cohort (12-33 weeks), 3 cohort (24-44 weeks) and 4 cohort (36-56 weeks).The instruments used to collect information have been the following: a questionnaire completed by the very own mothers and which we weekly collected. A semi-structured weekly tape-record interview. Finally, we carried out a three-hour observation every fortnight during the firs months and once a month from that age.The criterion we have followed to rate a period as a regression period has been the coexistence of three of the behavioural categories which typify the episodes according to the previously quoted work: a) an increase of the bodily contact between mother and child, b) an increase in crying and irritability behaviours, c) the presence of a third disruptive element like alteration in the sleep-wakefulness rhythm, decrease of ingestion, very altered activity, drowsiness, etc...In relation to data, the maximum percentages of the regression periods found in our research appear distributed along the following weeks: 5, 8, 12-13, 18, 26-27, 35, 43 and 52. The mean of lasting of a regression period was of 2 weeks in a range of 1-4 weeks.Our data confirm the ones obtained in van de Rijt-Plooij & Plooij's research. Still we can appreciate some differences what suggested that the culture could be also operating in the presentation shape of regression periods.About relationship between regression periods and new behaviours emergence (transition periods), the results prove that the maxim peaks of regression appear placed some week before the peak of transition periods. The hypotheses that assist that the regression periods are index of transition periods is confirmed by the results.