Functia Integrativa a Creierului.pdf
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Transcript of Functia Integrativa a Creierului.pdf
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, 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–tim interactions.
(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
heterodimers are 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 (Reppert and 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- semnalizare prin proteine G
Efectul activarii
tractului retino-
Nucleul suprachiasmatic (SCN)
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).
Light phase response curves (PRC)
tractului retino-
hipotalamic (RHT) Efectul activarii IGL–RHT
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� 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).