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).