Neuropsykologins historia och teori

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1 Neuropsykologins historia och teori Edwin Smith-papyrusen ca 1600 f. Kr. Jarl Risberg Neuroutbildarna i Lund Kurs Neuropsykologisk fördjupning Edwin Smith-papyrusen beskriver hur man behandlar skador på skallen och bröstkorgen. Texten är skriven med hieratisk skrift och innehåller 48 olika skadebeskrivningar där 27 avhandlar olika skallskador och 6 avhandlar olika ryggmärgsskador. Alla fall delas upp i prognoserna gynnsamma, ovissa och ogynnsamma och presenteras i saklig ordning med namn, undersökningsfynd, diagnos och behandling. Texten beskriver bland annat att förlamningar i ena kroppshalvan kan orsakas av hjärnskador på den motsatta sidan, ett fynd som återupptäcktes mer än år senare. René Descartes

2 Paul Broca Phineas Gage Carl Wernicke

3 Santiago Ramon y Cajal ( ) och Camillo Golgi ( ) delade Nobelpriset i medicin eller fysiologi Cajal utvecklade neuronteorin: Hjärnan består av otaliga nervceller som är individuellt fungerande och som inte står i direkt anatomisk kontakt med varandra. Varje neuron överför information till andra neuron via nervfibrer. Golgi stödde inte neuronteorin utan hävdade att nervsystemet är ett enda anatomiskt sammanhängande nätverk. Aleksander Luria

4 Luria s Theory of Higher Cortical Functions The higher psychological processes represent complex functional systems They are social in their genesis Mediated by language in their structure Conscious in their performance Definition of a Functional System Brain functioning is not localized in a specific area of cerebral tissue, but is distributed in a constellation of cooperating zones of the cerebral cortex and the sub-cortical structures Luria s Theory of Higher Cortical Functions There are three fundamental areas of the brain which necessarily participate in any, even the least complex, psychological activity, each of which exerts a special influence in the organization of psychological processes Donald Hebb ( ) The Organization of Behavior (1949) 4

5 Long-Term Potentiation (LTP) D.O. Hebb 1949 The NMDA receptor THE SYNAPTIC PLACTICITY AND MEMORY HYPOTHESIS Activity-dependent synaptic plasticity is induced at appropriate synapses during memory formation, and is both necessary and sufficient for the information storage underlying the type of memory mediated by the brain area in which that plasticity is observed. Morris et al

6 Funktion Vänster hemisfär Höger hemisfär Syn Bokstäver, ord, enkla bilder Komplexa mönster, ansikten Hörsel Språkljud Icke-språkliga ljud, musik Känsel - Avkänning av föremål Rörelser Viljemässiga rörelser Rörelser i rumsliga mönster Minne Språkligt minne Icke-språkligt minne Språk Tala, läsa, skriva och räkna Språkmelodi Rumsligt tänkande - Geometri, riktning, former De första försöken att använda funktionell hjärnavbildning inom neuropsykologin (ca 1965) Risberg and Ingvar 1973 Förändringar av hjärnans blodflöde under kreativt tänkande Högkreativa Lågkreativa Carlsson, Wendt & Risberg, Neuropsychologia, 38, ,

7 PET -undersökning Aktivering av synbarken när man tittar på ansikten (gul-orange) eller hus (blå) Haxby et al Luria s Theory of Higher Cortical Functions Hypothetical interactions between networks when constructing a sentence The higher psychological processes represent complex functional systems They are social in their genesis Mediated by language in their structure Conscious in their performance Fuster J.,

8 Maps of structural brain connectivity from nineteenth century cerebral cartography and present day connectomics From regions to connections and networks: new bridges between brain and behavior (a) White matter association pathways by the Belgian anatomist Arthur Van Gehuchten. (b) A similar lateral view by the Austrian neurologist Heinrich Obersteiner. (c) An map of the brain's white matter connections represented as a network. Spheres mark cortical network nodes and lines represent their connections as mapped with diffusion imaging and tractography. The network is shown with nodes placed into their anatomical coordinates, preserving the spatial embedding of the network. (d) The same network as in (c), but with nodes placed by a widely used visualization algorithm that projects the network into two dimensions and places nodes such that densely connected regions are located nearby. Most highly connected parts of the brain, corresponding to portions of the cingulate and posterior parietal cortex, are placed in the center of the plot. Activation studies examine relations between localized changes in signal amplitude and specific behaviors. Connectivity based studies take into account how communication between distributed areas contributes to individual behaviors. Network modeling methods, emphasizing modularity and the role of network topology, enable the discovery of particular subsystems and how these subsystems relate to behavior. Multivariate statistical models aim to directly model the relationship between distributed connection patterns and combinations of cognitive-behavioral phenotypes. Mišić & Sporns: Current Opinion in Neurobiology, Volume 40, 2016, 1 7 The Default Mode Network (Vilonätverket) Parcellation and network community detection Buckner, R.L., Andrews-Hanna, J.R & Schacter, D.L. (2008). The brain s default network. Anatomy, function, and relevance to disease. Annals of the New York Academy of Sciences, 1124, (a) A boundary map derived from group-averaged (n = 160) resting-state functional connectivity. Red/yellow colors in edge density mark locations on the cortical surface where patterns of functional connections exhibit abrupt changes. Black/blue/purple colors correspond to boundaries between relatively homogeneous regions. (b) A network map of the cerebral cortex derived by clustering resting-state functional connectivity measured in a large number of participants (n = 1000) into seven network communities. These communities correspond to several well-studied resting-state or intrinsic connectivity networks. Sporns, 2015 Seventeen network communities Yeo et al., The organization of the human cerebral cortex estimated by intrinsic functional connectivity. J Neurophysiol. 2011, 106(3):

9 Cajals avbildningar av gliaceller Det finns uppskattningsvis gliaceller i hjärnan. De vanligaste gliacellerna är protoplasmatiska astrocyter som kan ha upp 2 miljoner utskott. Utskotten är i kontakt med och reglerar nervceller, synapser, blodkärl och angränsande astrocyter. The Evolving View of Astrocytes Hypothetical illustration of the major cellular components comprising the neurovascular unit in the cerebral cortex. In addition to the electrically active neurons, the brain contains numerous glial cell types, including astrocytes, oligodendrocytes, and microglia. Astrocytes are the most plentiful of these glial cells and have unique physical attributes: They contract blood vessels as well as neuronal synapses at a structure called the tripartite synapse. Consequently, they play important roles in synaptic development and modulation of homeostasis as well as in the delivery of nutrients from the circulation to neurons and act as an intermediate to relay neuronal activity to the vasculature to control blood flow. Philip G. Haydon, Cerebrum, October by American Physiological Society Jessica A. Filosa, and Jennifer A. Iddings Am J Physiol Heart Circ Physiol 2013;305:H609-H619 The tripartite synaps Bidirectional Neuron-astrocyte Communication (a) Electron micrograph showing a presynaptic (Pre) and postsynaptic (Post) terminal enwrapped by the astrocytic process (green) forming the tripartite synapse. (b) The close association of the astrocytic process with the presynaptic and postsynaptic terminals exerts crucial roles in clearing K + ions that accumulate following neuronal activity, and in the uptake of the synaptic transmitter glutamate by the activity of plasma-membrane glutamate transporters. Additionally, neurotransmitter release from presynaptic terminals can activate astrocytic receptors that induce Ca2+ elevations which in turn triggers the release of gliotransmitters from these cells. The Evolving View of Astrocytes, Philip G. Haydon, Cerebrum, October 2016 (A) Schematic drawing of the tripartite synapse illustrating the location of low and high affinity ligand receptors. (B) Neurotransmitters rapidly activate low affinity receptors at the postsynaptic neuronal membrane and diffuse outside the synaptic cleft to activate high affinity receptors at the astrocytic membrane. (C) Gliotransmitters activate high affinity receptors at perisynaptic locations in the neuronal membrane. Neurotransmitter (B) or gliotransmitter (C) decreasing concentrations over distance from release sites is illustrated by different color intensity. Gliotransmitters Travel in Time and Space Alfonso Araque, 1,2 Giorgio Carmignoto, 3 Philip G. Haydon, 4 Stéphane H. R. Oliet, 5,6 Richard Robitaille, 7,8 and Andrea Volterra 9 Neuron Volume 81, Issue 4, 19 February 2014, Pages

10 Synaptic Modulatory Actions of Gliotransmitters Low levels of synaptic activity (blue arrow, left) evoke rapid, spatially restricted Ca2+ elevations at an astrocytic process (red trace) resulting in a gliotransmitter release that locally modulates synaptic transmission (green arrow, right). The change in synaptic efficacy due to gliotransmitter-mediated regulation of the probability of release is illustrated as an increase in the mean amplitude of excitatory postsynaptic events (dashed and solid blue line Layout of neuron cell bodies, dendritic network and axonal fibres (grey) transmitting action potentials (red arrows). Araque et al. Neuron 2014 Ca2+ elevations evoked at an astrocytic process by an intense activity of an individual synapse diffuse to a nearby process (red arrow) to trigger gliotransmitter release that affects nearby synapses (right). The red superimposed traces are the integrated Ca2+ response (solid line) and the elementary Ca2+ response (dashed line). As a result of this astrocyte modulatory action, synaptic transmission (solid blue line) can be either potentiated or depressed, while the elements that are not the focus are greyed. Multiple Ca2+ events at different processes evoked by simultaneously active synapses are spatially and temporally integrated (left) resulting in a global, long lasting Ca2+ elevation that can affect synaptic transmission in the territory of individual astrocytes (right). The global Ca2+ response (solid line) and the integrated Ca2+ response (dashed line, same as solid line in B) are reported. Note the different time scale of Ca2+ traces in (A), (B) and (C). (a) One dendrite of interest is designated by arrowheads. (b) The mosaic of astrocytic domains is superimposed to the background neuronal network. (c) Different contiguous segments of the same dendrite (arrowheads in a) intersect distinct astrocytic domains. Synapses are controlled independently within each of these domains (synaptic islands). (d) One astrocyte covers portions of different dendrites, belonging to four distinct neurons, surveying the activity of a total synapses. Thomas Papouin et al. Phil. Trans. R. Soc. B 2017;372: Astrocyterna är engagerade i sömn och vakenhetsregleringen Astrocytes and human cognition Modeling information integration and modulation of neuronal activity During desynchronized epochs, populations of neurons do not fire in a coordinated fashion and astrocytic Ca 2+ signaling is low. Astrocyte Ca 2+ activity increases in the local circuit through a variety of mechanisms (arrow 1; green), followed by (arrow 2) accumulation of extracellular glutamate (cyan) and a shift (arrow 3) into the slow-oscillation state. Poskanzer & Yuste, PNAS, April 27, A biophysical Global Workspace composed of a network of astrocytes. Blue stars represent protoplasmic astrocytes and red trees represent neurons. Each astrocyte participates in a tripartite synapse, being activated by the pre-synaptic neuron. Alfredo Pereira Jr, Fábio Augusto Furlan Progress in Neurobiology, Volume 92, Issue 3, 2010, Astrocytes and human cognition Modeling information integration and modulation of neuronal activity Consciousness as The Feeling (astroglial sentience) of What Happens (neuronal awareness). Awareness and sentience of information patterns can occur unconsciously, but when they occur together the informational content becomes conscious. Alfredo Pereira Jr, Fábio Augusto Furlan Progress in Neurobiology, Volume 92, Issue 3, 2010, Astrocyternas betydelse för hjärnans struktur och funktion 1. Stödjande hjärnans lim 2. Reglerar jon- och vatten-homeostas, avfallshantering 3. Upprätthållande av blod-hjärnbarriären 4. Regleringen av hjärnans blodflöde 5. Bildandet av stamceller 6. Bildandet av synapser 7. Aktivt engagemang i synaptisk transmission 8. Avger neurotransmittorer av alla typer (glutamat, GABA m fl) 9. De ca 2 miljoner utskotten från en protoplasmatisk astrocyt påverkar nervceller, synapser och blodkärl inom ett avgränsat område (domän). 10.Domänerna kan snabbt överföra information mellan varandra, och utgör ett underlag för vakenhetsreglering, perception, minne och medvetande. 10

11 Hoppas att era astrocyter inte är helt SLUT Tack för intresset! 11