Introduction to neurosciences for Cognitive MSs. Neurobiology Introduction to neurosciences for Cognitive MSs.

Edwin Smith surgical papirus

Anatomical and Functional Neuroanatomy Tutorial: www.neuropat.dote.hu

The Nervous System © 2004 John Wiley & Sons, Inc. Huffman: PSYCHOLOGY IN ACTION, 7E

Részei Agy: agytörzs. Kisagy és agykéreg gerincvelő Perifériás idegek autonóm szomatikus enterális

Agytörzs középagy Híd nyúltagy

Agykéreg: 4 lebeny Frontális (homlok) Temporális (halánték) Parietális (fali) Occipitális (nyakszirti)

Agy frontális lebeny - motor activity, tervezés & mozgás, beszélt nyelv, affektív tényezők temporalis lebeny – hallás, nyelv, (Wernicke' s area) parietális lebeny - somatosensation, tér érzékelés occipitalis lebeny - látás

Agy és agykéreg

Agykéreg- cortex szürke fehér Fig. 2.23

Broadmann áreák Fig. 3.7

Funkcionális specializáció Motoros Szenzoros Szomatoszenzoros Halló Látó Asszociációs

Motoros kéreg – homloklebeny

Szomatoszenzoros kéreg- fali lebeny

Hallókéreg- halántéklebeny Auditory Cortex

Látókéreg- nyakszirti lebeny Parietális - Hol? Temporális - Mi? Fig. 2.29

Asszociációs kéreg Nem szenzoros, Nem motoros Magasabb funkciók, pld beszéd.

Brain normalization to Standard Tailarach Coordinates

Brain Segmentation and 3D reconstruction

Neuron-idegsejt Neuronális hálózatok Jan Purkinje Purkinje cell – first viewed in 1837

Cajal és Golgi – 1906 Nobel Díj Santiago Ramon y Cajal Camillo Golgi

A neuron ca 1012 neuron/agy

Neurons, Membranes, and Electrical Potentials

Neuronal Membrane Lipid kettős réteg Integráns és perifériás membránfehérjék Ami átmehet: gázok lipidoldékony molekulák vízmolekulák Ami nem: hidrofil semleges molekulák ionok Többi: transzporttal – lehetőségek: ioncsatornák passzív karrierek (transzporter) primer pumpák

Transmembrane Transport a) communication among neurons neural systems: * action potential * synaptic signaling b) receptor – brain communication heart muscle signaling and regulatory processes Monovalent Ion Channels Electrically active cells, such as neurons and muscle cells, maintain a resting membrane potential of approximately –70 mV. Neurotransmitters depolarize or hyperpolarize the cell membrane by opening ion channels within the membrane that are either an integral part of the receptor molecule (ligand-gated ion channels) or that are linked to the receptor through a G-protein mediated mechanism (ion channel-linked receptors). Occupation of the ligand recognition site of a ligand-gated ion channel induces changes in the conformation of the channel-forming protein such that ion flux across the membrane is increased. In contrast, voltage-gated channels open or close in response to a change in voltage across the adjacent cell membrane. These channels are responsible for the generation of action potentials in electrically excitable cells. If Na+ permeability is increased, Na+ moves into the cell down its concentration gradient and the membrane becomes depolarized in the region of the open channel. In contrast, if Cl- permeability is increased, the membrane will become hyperpolarized in the region of the open channel. Depolarization is associated with generation of action potentials, degranulation, neurotransmission, and muscle contraction. Hyperpolarization is associated with inhibition of these processes. The resting membrane potential is restored and maintained by activation of the Na+-K+-ATPase pump that actively extrudes Na+ from the cell.

Ion Concentration Gradients

Channel Permeation - Nernst Consider a cell containing a high concentration of KCl External [KCl] is low Consider the cell membrane to be permeable to K+ only. after some diffusion equilibrium The Nernst equation is fundamental to the understanding of ion channel behavior. It assumes two things: 1. There is a difference in the concentration of an ion across a membrane 2. The membrane is selectively permeable to one type of ion only. Even though the second assumption is never completely true, the Nernst potential can give us a good idea of what’s happening. initial condition Vr is known as the: Nernst potential reversal potential zero current potential equilibrium potential

Channel Permeation: Ohm's Law Current (flow) is equal to voltage (driving force) times conductance (1/resistance) I = (V-Vr) G Current (I) is measured in amps (pA, nA, µA) Voltage (V) is measured in volts (mV) Conductance (G) is measured in Siemens (pS, nS) I hope you remember Ohm’s law from physics class. If you are a bit afraid of electricity, consider the flow of water through a pipe as an analogy. Voltage is like pressure Current is like water flow rate (volume/time) Resistance is like the resistance of the pipe.

Properties of electrotonic potentials Graded response determined by the strength of the stimulus Depolarizing or hyperpolarizing direction Time course determined by the membrane time constant τ = R • C Response in elongated cells determined by the membrane length constant λ = rm / ri No refractory periods Passive, linear membrane behaviour, voltage dependent Na channels do not open

Ion Flow in 5 Phases of the Action Potential

the peak of the action potential is determined by – the sodium equilibrium potential – the time course of sodium channel inactivation • The peak of AP approaches the sodium Nernst-potential (~ +60 mV)

AP propagates without decrement Because the AP in one region causes depolarization that triggers an AP in an adjacent region or node Factors affecting conduction velocity • Size • Myelination

Myelin Myelin is a fatty, waxy substance coating the axon of some neurons. Functions: Speeds neurotransmission Insulates neurons from each other Makes neurotransmission more efficient © 2004 John Wiley & Sons, Inc. Huffman: PSYCHOLOGY IN ACTION, 7E

How Impulses Travel Down the Neuron

Summation of EPSPs and IPSPs

Synaptic Transmission and Brain Neurochemistry