Extraction of spontaneously occurring activity patterns from an electrophysiological signal

Abstract

To be able to elicit desired percepts using a cortical visual prosthesis, is it essential to understand the functional structure of the neural network under the implant. However, in a blind individual the functional proper- ties of neurons cannot be measured by recording responses to visual stimuli and information can only be extracted from spontaneous activity. Spon- taneous activity in the primary visual cortex (V1) of anesthetized primates has been shown to encode information about local functional architecture of the neural network. Particularly, inference of the orientation-preference map from spontaneous activity has been achieved in non-human animals using in- vasive imaging techniques that are not intended for applications in humans. Whether the same inference is possible with spatially sparse electrophysiolo- gical recordings from a micro-electrode array that is currently used as a cortical visual prosthesis remains unknown. The aim of this thesis is to use automatic spatial pattern detection algorithm for orientation preference map inference from spontaneous activity and compare outcomes using four differ- ent variables extracted from signal recorded with intracranial micro-electrode arrays in awake macaque monkeys. 1

Pro vyvola ́nı ́ smysluplny ́ch vjemu ̊ pomocı ́ kortika ́lnı ́ zrakove ́ prote ́zy je nutne ́ porozume ̌t funkc ̌nı ́ architektur ̌e neuronove ́ sı ́te ̌ v mı 'ste ̌ implanta ́tu. U nevidome ́ho jedince vs ̌ak nelze me ̌r ̌it funkc ̌nı ́ vlastnosti neuronu ̊ za ́znamem reakcı ́ na vizua ́lnı ́ podne ̌ty a informace lze zı 'skat pouze ze sponta ́nnı ́ akt- ivity. Uka ́zalo se, z ̌e sponta ́nnı ́ aktivita v prima ́rnı ́ zrakove ́ ku ̊r ̌e (V1) an- estetizovany ́ch prima ́tu ̊ ko ́duje informace o loka ́lnı ́funkc ̌nı ́architektur ̌e neur- onove ́ sı ́te ̌. Konkre ́tne ̌ bylo dosaz ̌eno odvozenı ́ mapy orientac ̌nı ́ch preferencı ́ ze sponta ́nnı ́ aktivity u zvı ́r ̌at za pouz ̌itı ́ invazivnı ́ch zobrazovacı ́ch tech- nik, ktere ́ nejsou urc ̌eny pro aplikace u lidı ́. Zda je stejne ́ odvozenı ́ moz ̌ne ́ s prostorove ̌ r ̌ı ́dky ́mi elektrofyziologicky ́mi za ́znamy z mikroelektrodove ́ho pole, ktere ́ je v souc ̌asnosti pouz ̌ı ́va ́no jako kortika ́lnı ́ vizua ́lnı ́ prote ́za, nenı ́ jasne ́. Cı ́lem te ́to pra ́ce je pouz ̌ı ́t algoritmus pro odvozenı ́ mapy orientacı ́ ze sponta ́nnı ́ aktivity a porovnat vy 'sledky pomocı ́ c ̌tyr ̌ ru ̊zny ́ch prome ̌nny ́ch extrahovany ́ch ze signa ́lu nahrane ́ho pomocı ́ intrakrania ́lnı ́ch mikroelektro- dovy ́ch polı ́ u bde ̌ly ́ch makaku ̊. 1