Functia Integrativa a Creierului
The evolution and classification of primates. Tarsiers are generally considered to be prosimians, but they are related more closely to anthropoids, so they are recognized as haplorhine primates. Despite the ancient split of prosimian and anthropoid primates, they share many brain features that are unique to primates. Tree shrews, bats, and flying lemurs are thought to be close relatives of primates, forming the superorder Archonta, but the composition of Archonta is in doubt. mya, millions of years ago.
Circadian timing system (CTS). The control feature of the CTS is the circadian pacemaker. Information from photoreceptors is conveyed by entrainment pathways to the pacemaker. The pacemaker has a rhythmic output that drives "slave" oscillators, which control functions that exhibit circadian regulation.
Features of per timinteractions. (A) Profiles of PER and TIM mrna and protein levels across a light (open bar) dark (filled bar) cycle. The shaded area shows when PER TIM heterodimersare present in the nucleus. (B) Structures of PER and TIM proteins. The connecting lines indicate areas of each protein thought to be involved in PER TIM dimerization. A, acidic region; B, basic region. (C) Interdependent negative feedback control loops of per and tim(reppertand Sauman, 1995).
Organizarea Nucleului Suprachiasmatic (SCN) la mamifere. (1) zona centrala: colocalizare GABA cu VIP sau GRP (gastrin-releasing peptide) (2) zona marginala: colocalizare GABA cu arginin vasopresina (AVP) sau calretinina (CAR) Glu, glutamate; 5HT, serotonin; ACH, acetylcholine; NA, noradrenaline; NPY, neuropeptide Y.
La animale tinute constant in intuneric, activitatea este inregistrata (bare orizontale) pentru pulsurile luminoase indicate. Efectele stimularii luminoase sunt determinate rezultand curba de raspuns [phase response curve (PRC)].
Melanopsin - fotopigment localizat in celulele ganglionare fotosenzitive din retina, responsabil de raspunsul sistemului circadian la modificari de luminozitate. - inrudit structural cu opsinele de la nevertebrate - semnalizare prin proteine G
Nucleul suprachiasmatic (SCN) Efectul activarii tractului retinohipotalamic (RHT) Efectul activarii IGL RHT Light phase response curves (PRC) Tractul retino-hipotalamic (RHT) trimite proiectii catre Nucleul suprachiasmatic (SCN) si intergeniculat (IGL). Nucleul suprachiasmatic controleaza ciclul repaus-activitate. Functia de pacemaker a Nucleul suprachiasmatic este influentata de activitatea locomotorie prin intermediul nucleului intergeniculat (IGL).
Distributia proiectiilor complexului nucleu suprachiasmatic (SCN) zona subparaventriculara (SPVZ)
Organization of avian circadian systems. Depending on the type of bird, the pineal, eye, or SCN may be a circadian pacemaker driving the rest activity rhythm. The interactions of these structures are shown diagrammatically.
Diagram of a sagittal view of rat brain showing the pathways controlling pineal melatonin production. The RHT runs from the retina to the SCN, which in turn projects to the paraventricular nucleus of the hypothalamus (PVH). The PVH projects to the intermediolateral cell column of the upper thoracic cord (IML, T1 T2), which provides preganglionic input to sympathetic neurons in the superior cervical ganglion (SCG) innervating the pineal gland.
The SCN and behavioral state control. The SCN projects to the ventrolateral preoptic area (VLPO), an area mediating sleep. VLPO inhibits the arousal activity of the tuberomammillary nucleus during sleep. The SCN provides an arousal-promoting input to the posterior hypothalamic area, particularly to hypocretin neurons, which project upon the neocortex and subcortical arousal areas.
Hypocretin 1 & 2 / Orexine A & B -Neuropeptide excitatorii aparute timpuriu in evolutia vertebratelor (33 / 28 am.ac., cu ~ 50% secventa identica), descoperite in 1998 -Produse intr-o populatie mica de celule din hipotalamusul lateral si posterior, care trimit proiectii catre creier -Se leaga de receptori specifici OX1 si OX2 cuplati cu proteine G -Functii: reglarea eliberarii de Ach, serotonina, noradrenalina cresterea apetitului, cresterea consumului energetic, asociat cu starea de veghe implicate in reglarea somnului (absenta lor determina narcolepsie) rol in stabilizarea ciclului somn-veghe -Studii farmacologice actuale: -agonisti ai rec. OX pentru tratamentul narcolepsiei -antagonisti ai rec. OX pentru insomnie
Rate intensity function for electrical self-stimulation of the brain. Pharmacologic agents shift the curve left (e.g., amphetamine or cocaine) or right (e.g., catecholamine-depleting agents, such as α-methyl-p-tyrosine and reserpine, and catecholamine receptor blockers, such as chlorpromazine and pimozide).