Evoked Potentials in Diabetic Syndrome of Rats Before and After Two Months of Methadone Treatment

The effect of two months treatment with methadone (0.87 mg/kg per os, daily) on the somatosensory evoked potentials (SEPs) in female control and diabetic rats were studied. Diabetes was induced by alloxan monohydrate (65 mg/kg i. v.). SEPs obtained after electrical stimulation of the contralateral forepaw and recorded from the scalp, by an non invasive method, showed high reproducibility. Prolonged latency (156%) and a marked amplitude enhancement (371%) characterized the mid-latency SEPs following 64 days methadone treatment of healthy rats. Experimental diabetes induced significant alteration of both parameters; amplitude decrease of earlier components (Nl, P2) and delayed latency of later ones (P3). Two months methadone treatment of diabetic rats not only leads to the recovery but also augmented P2 (P25) amplitude (225%). It was concluded that no essential differences exist in the methadone effect on control (healthy) and diabetic Wistar female rats

Upravljanje robotom pomoću anticipacijskih potencijala mozga

Recently Biomedical Engineering showed advances in using brain potentials for control of physical devices, in particular, robots. This paper is focused on controlling robots using anticipatory brain potentials. An oscillatory brain potential generated in the CNV Flip-Flop Paradigm is used to trigger sequence of robot behaviors. Experimental illustration is given in which two robotic arms, driven by a brain expectancy potential oscillation, cooperatively solve the well known problem of Towers of Hanoi.U posljednje vrijeme je u području biomedicinskog inženjerstva postignut napredak u korištenju potencijala mozga za upravljanje fizičkim napravama, posebice robotima. U radu je opisana mogućnost upravljanja robotima pomoću anticipacijskih potencijala mozga. Oscilacijski potencijal mozga generiran u CNV (Contingent Negative Variation) flip-flop paradigmi se koristi za okidanje slijeda ponašanja robota. U radu je prikazana eksperimentalna ilustracija rješavanja dobro poznatog problema Hanojskih tornjeva pomoću dvije robotske ruke upravljane moždanim potencijalom očekivanja

Cognitive Auditory Evoked Potentials in Children with Special Language Impairment

Perception and discrimination of auditory and speech stimuli in children aged 7–9 years with either receptive (n=6) or expressive (n=5) type of special language impairment and 7 healthy age-matched controls was investigated using evoked potential technique. The measurements were performed with a 32-channel Neuroscan electroencephalographic system. Two types of stimuli were applied, pure tones (1 kHz and 2 kHz) and double syllabi consisting of one consonant and one vocal characteristic of Croatian language. The stimuli were presented in an oddball paradigm, requiring a conscious reaction for the subjects. Latencies and amplitudes of P1, N1, P2, N2, P3, N4, and SW waves were analized, as well as the reaction time and number of responses. There were found no statistically significant difference between children with special language impairment and the control group in average response time and number of responses to tone burst or double syllable. Analysis of variance of all used variables showed a statistically significant difference in P3 and Sw wave latencies after double syllable stimulation, P3 and N4 waves latencies after target stimulation, P2 and Sw wave amplitude; and in N1 wave amplitude after pure tone stimulation. Our study showed that children with speech and language disorder take longer time to perceive and discriminate between either tonal or speech auditory stimuli than children with typical speech and language development

Somatosenzorni evocirani potencijali pobuđeni vibracijskom stimulacijom: parametri stimulacije

In a clinical application, a method for an examination of a vibratory sense is not very objective and it depends on an active cooperation of a patient, which cannot be achieved in every situation. The aim of this research is to define parameters of an evoked potentials method with a vibratory stimulation technique which would establish reliable and repeatable results applicable in a clinical usage. During the research, different experimental conditions were performed (different methods of stimulation, different stimulation frequencies, different stimulus durations, different areas of stimulation). Presented results confirm the initial assumption that it is possible to detect reliable and repeatable cortical potentials evoked by the vibratory stimulation. Characteristic shapes and spatiotemporal distributions of evoked responses are established. Optimal stimulation parameters are defined as a prelude for a future research.U kliničkoj uporabi, metoda ispitivanja dubokog osjeta pomoću vibracija nije objektivna i zahtijeva aktivnu suradnju pacijenta što u brojnim situacijama nije moguće. Svrha ovog istraživanja je definirati parametre metode evociranih po-tencijala pobuđenih vibracijskom stimulacijom primjenjive u kliničkoj uporabi, koja će davati pouzdane i ponovljive rezultate. Tijekom ispitivanja, primijenjeni su različiti eksperimentalni uvjeti (različite tehnike stimulacije, različite frekvencije stimulacije, različita trajanja stimulacije, različita područja stimuliranja). Rezultati potvrđuju početnu pretpostavku da je moguće detektirati pouzdane i ponovljive kortikalne potencijale pobuđene vibracijskom stimulacijom. Utvrđeni su karakteristični valni oblici evociranih odgovora i njihove prostorno-vremenske karakteristike. Optimalni stimulacijski parametri su definiriani kao podloga za buduća istraživanj

Categorization and vagueness: How are words stored in the mental lexicon

Za razliku od filozofije, u kojoj se neodređenost shvaća kao problem vezan za Eubulidove paradokse (npr. paradoks gomile) i pitanje istinitosti sudova koji sadrže predikate kao što su »visok« ili »težak«, u lingvistici se neodređenost shvaća kao bitna i sveprisutna osobina komunikacije. Cilj je ovoga istraživanja bio identificirati psiholingvistički efekt neodređenosti i pokazati na koji bi način kognitivni model ljudske komunikacije mogao uključiti neodređenost kao svoju bitnu osobinu. Teorijska podloga provedenoga eksperimenta Gärdenforsova je teorija pojmovnih prostora u kojoj se neodređenost veće za kategorizaciju pojmova u umnom rječniku. Stoga je upotrijebljena paradigma slaganja riječi i slike (picture–matching paradigm) u kojoj ispitanici moraju kategorizirati riječ s obzirom na ponuđenu sliku. Mjerenje evociranih potencijala pokazuje dva različita vala kao specifični odgovor na zadatak, komponentu N400 vezanu za semantičku obradu (prizivanje riječi iz umnog rječnika) i P600 vezanu za integraciju slike i riječi. Dok je N400 veći kad god riječ ne odgovara slici, P600 je veće amplitude specifično na pojmove koji su neodređeni u odnosu na sliku. Rezultati upućuju na prizivanje riječi iz umnog rječnika kao (najmanje) dvostupanjski proces u kojem se u prvoj fazi riječ prepoznaje, a u drugoj veže u kontekst.In this study event–related potentials method (ERP) was used to study the effect of vagueness in language. In difference to philosophy, where vagueness is a source of Sorites paradoxes, in linguistics vagueness is regarded as a design feature of human language. In this sense vagueness is modeled in contemporary cognitive science as a feature that allows for keeping the actual amount of exchanged information between the intelligent agents at minimum while preserving the effectiveness of communication. The theory of meaning that accounts for vagueness in language is Gärdenfors’ theory of conceptual spaces. According to this theory the concepts are positioned in a continuum along a vector that represents a feature, e. g. tallness. Gärdenfors introduces a crisp function that corresponds to categorization. The crisp function divides the conceptual space into two parts (tall and non–tall regions in the given example). Categorizationis therefore essential for the account of vagueness because it is the source of vague concepts (e.g. of being tall in a continuum of precise measures of tallness, say, in millimeters). In this experiment we used a well–known picture matching paradigm in which participants had to decide whether a word matches the given photograph or not (categorization task). The vagueness condition was added by adding hyponyms as words to the categorization task, thus creating four experimental conditions (non–vague match, vague match, non–vague mismatch and vague mismatch). The difference in N400 component of ERP was expected for all vague and mismatch conditions. However, two different components were obtained: both N400 for all mismatch conditions (including vague) and P600 for vague conditions. Therefore, both the experimental effect of vagueness was obtained and the results can be interpreted in terms of vagueness as facilitation of language communication. These results also indicate that retrieving words from mental lexicon is (at least) a two–phase process in which the word activated by the picture is (1.) compared with the stimulus word and then (2.) integrated into the context. The first phase is highly automatic and beyond speaker’s control while the second depends on the context: vague words are correctly categorized, but require additional processing costs if there is no other reason for using them

VESTIBULAR NEURONITIS: PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT

Vestibularni neuritis (VN) jedan je od najčešćih perifernih uzroka vrtoglavice. Kalorimetrijsko ispitivanje vestibularnog organa zlatni je standard u dijagnostici VN-a. Ipak, novija istraživanja ističu praktičnost primjene kliničkih testova koji se izvode uz krevet bolesnika, a usporedivi su s osjetljivosti i specifičnosti u odnosu prema zlatnom standardu. Riječ je o »head thrust«, »head heave«, »head shake« i vibracijskom testu. Osim kalorimetrijskog testiranja kao zlatnog standarda u dijagnostici VN-a, vestibularni evocirani miogeni potencijali (VEMP) mogu razlikovati oštećenje gornje i donje grane vestibularnog živca, ali i periferno od centralnog oštećenja. Unatoč tomu što je u liječenju VN-a već dugo ustaljena primjena glukokortikoida, novija istraživanja opravdanost njihove upotrebe dovode u pitanje, a s druge se strane naglašava važnost fizikalne rehabilitacije. U ovome preglednom članku bit će iznesene najnovije spoznaje o patofiziologiji, dijagnostici i liječenju bolesnika s VN-om.Vestibular neuritis (VN) is one of the most common causes of peripheral vertigo. Caloric testing has been the traditional gold standard for detecting a peripheral vestibular deficit, but some recently developed bedside tests (head thrust, head heave, head shake and vibration test) were evaluated as a good alternative with similar sensitivity and specificity. These tests have shown both diagnostic value in the short term and prognostic value in the long term, and have availability and ease of use as an advantage. As an addition to clinical examination, vestibular evoked myogenic potentials can differentiate between involvement of superior and inferior branch of the vestibular nerve, but also between peripheral and central lesions. Although glucocorticoids are currently widely used in the treatment of VN, there is a lack of evidence for the validity of their administration. There are a number of high quality clinical trials that suggest vestibular rehabilitation exercises, which are based on the mechanisms of vestibular compensation, in the managment of VN. This review will focus on the latest developments in the pathophysiology, diagnosis and treatment of patients with VN

Vestibularni neuronitis: patofiziologija, dijagnoza i liječenje [Vestibular neuronitis: pathophysiology, diagnosis and treatment]

Vestibular neuritis (VN) is one of the most common causes of peripheral vertigo. Caloric testing has been the traditional gold standard for detecting a peripheral vestibular deficit, but some recently developed bedside tests (head thrust, head heave, head shake and vibration test) were evaluated as a good alternative with similar sensitivity and specificity. These tests have shown both diagnostic value in the short term and prognostic value in the long term, and have availability and ease of use as an advantage. As an addition to clinical examination, vestibular evoked myogenic potentials can differentiate between involvement of superior and inferior branch of the vestibular nerve, but also between peripheral and central lesions. Although glucocorticoids are currently widely used in the treatment of VN, there is a lack of evidence for the validity of their administration. There are a number of high quality clinical trials that suggest vestibular rehabilitation exercises, which are based on the mechanisms of vestibular compensation, in the managment of VN. This review will focus on the latest developments in the pathophysiology, diagnosis and treatment of patients with VN

Somatosenzorni evocirani potencijali pobuđeni vibracijskom stimulacijom: parametri stimulacije

In a clinical application, a method for an examination of a vibratory sense is not very objective and it depends on an active cooperation of a patient, which cannot be achieved in every situation. The aim of this research is to define parameters of an evoked potentials method with a vibratory stimulation technique which would establish reliable and repeatable results applicable in a clinical usage. During the research, different experimental conditions were performed (different methods of stimulation, different stimulation frequencies, different stimulus durations, different areas of stimulation). Presented results confirm the initial assumption that it is possible to detect reliable and repeatable cortical potentials evoked by the vibratory stimulation. Characteristic shapes and spatiotemporal distributions of evoked responses are established. Optimal stimulation parameters are defined as a prelude for a future research.U kliničkoj uporabi, metoda ispitivanja dubokog osjeta pomoću vibracija nije objektivna i zahtijeva aktivnu suradnju pacijenta što u brojnim situacijama nije moguće. Svrha ovog istraživanja je definirati parametre metode evociranih po-tencijala pobuđenih vibracijskom stimulacijom primjenjive u kliničkoj uporabi, koja će davati pouzdane i ponovljive rezultate. Tijekom ispitivanja, primijenjeni su različiti eksperimentalni uvjeti (različite tehnike stimulacije, različite frekvencije stimulacije, različita trajanja stimulacije, različita područja stimuliranja). Rezultati potvrđuju početnu pretpostavku da je moguće detektirati pouzdane i ponovljive kortikalne potencijale pobuđene vibracijskom stimulacijom. Utvrđeni su karakteristični valni oblici evociranih odgovora i njihove prostorno-vremenske karakteristike. Optimalni stimulacijski parametri su definiriani kao podloga za buduća istraživanj