163 research outputs found
Borges, Petronio y la curiosa felicitas
No full textMuchos críticos han demostrado que Borges admiraba no solo a algunos autores latinos sino también la lengua latina. En este trabajo, nos ocuparemos de Petronio, un autor que tiene un lugar marginal dentro del canon borgeano, pero que, a pesar de eso, fue mencionado por el escritor argentino en varios pasajes de su corpus. En este caso, nos detendremos en la famosa expresión curiosa felicitas (Sat. 118) que Borges retoma en algunos de sus textos. Los objetivos de este artículo son: 1) reseñar las características y el significado de la famosa iunctura petroniana curiosa felicitas; 2) determinar dónde pudo haber leído Borges la formulación de Petronio; y 3) intentar definir qué consideración artística y estética tenía Borges del Satyricon.
As many scholars have shown, Borges admired not only some Latin authors but also the Latin language. In this paper, I will focus on Petronius, an author who has a marginal place in Borges’ canon, but who, nevertheless, was mentioned by the Argentine writer in several passages of his corpus. In this case, I will examine the famous formulation curiosa felicitas (Sat. 118) that Borges takes up in some of his texts. The aims of this paper are: 1) to review the characteristics and meaning of that famous Petronius’ iunctura; 2) to determine where Borges might have read Petronius’ expression; and 3) to try to define Borges’ artistic and aesthetic consideration of the Satyricon
The Rhetoric of Imperial Felicitas as a Political Tool in Late Antiquity
No full textThis article surveys the rhetoric of imperial felicitas (good luck) in Latin literature of the fourth and early fifth centuries in response to Erik Wistrand’s monograph Felicitas Imperatoria (1987). By including not only the emperor’s fortunes, but also the fortunes of the political community directly attributed to his presence or actions in its definition, it presents a more complete analysis of relevant political rhetoric. It demonstrates that the tropes of panegyric were manipulated by petitioners to facilitate political action. Finally, it concludes that the author of Historia Augusta intentionally subverts these tropes to envision a different political system for Rome
Effects of subthalamic Deep Brain Stimulation on dysarthria in Parkinson s disease
No full textTitelblatt und Inhaltsverzeichnis
Zusammenfassung
Fragestellung
Einleitung
Material und Methoden
Ergebnisse
Diskussion
Beurteilungsmaterial
LiteraturverzeichnisErkrankungen des zentralen Nervensystems, die Bewegungsstörungen verursachen,
führen vielfach auch zu Beeinträchtigungen der Sprechmotorik. Diese als
Dysarthrien bezeichneten Störungen haben Einschränkungen der
Kommunikationsfähigkeit zur Folge. Für die Betroffenen können sie daher eine
erhebliche Belastung im sozialen Leben darstellen. Bei Patienten mit M.
Parkinson kommt es in erster Linie zu einer Dopaminmangel bedingten
Dysfunktion der Basalganglien, die schließlich zu einer schweren Störung der
Bewegungsmuster führt. Auf der Ebene des Sprechens finden die typischen
Symptome der Körpermotorik ihr Korrelat in einer monotonen Sprechweise, einer
verwaschenen Artikulation sowie einer leisen und rauen Stimme. Als ein hoch
effektives, adjuvantes Therapieverfahren hat sich die tiefe Hirnstimulation
( Deep Brain Stimulation , DBS) für Patienten mit fortgeschrittenem M.
Parkinson etabliert. Hierbei werden Elektroden stereotaktisch in eine
Substruktur der Basalganglien, den Nucleus subthalamicus (STN), implantiert.
Es wird vermutet, dass die DBS des STN über eine Inhibition dieses
pathologisch überaktiven Kernareals wirkt. Trotz beachtlicher therapeutischer
Effekte des Verfahrens auf die körperliche Symptomatik des M. Parkinson,
bleibt die Wirkung auf sprechmotorische Störungen umstritten. Bisher wurden
sowohl Verbesserungen als auch Verschlechterungen der Sprechweise beschrieben.
In der vorliegenden Studie wurde der Einfluss von uni- und bilateraler DBS des
STN auf das Sprechen von 19 Patienten mit M. Parkinson untersucht. Da für das
Zustandekommen einer als gesund wahrgenommenen Sprechweise ein diffiziles
Zusammenspiel einzelner sprechmotorischer Funktionen notwendig ist, werden zur
Dysarthrie-Diagnostik generell neben perzeptiven Untersuchungsverfahren auch
technische Verfahren genutzt. In unserer Studie lag ein
Untersuchungsschwerpunkt auf der Selbstevaluation durch die Patienten sowie
auf der umfassenden, logopädischen Fremdbeurteilung. Die zusätzlich
angewandten technischen Untersuchungen umfassten eine Reihe von
Standardverfahren wie Videostroboskopie, Stimmfeldmessung,
Elektroglottographie (EGG), computergestützte Vokalanalyse und die Bestimmung
der Sprechgeschwindigkeit. Wir konnten nachweisen, dass die DBS des STN,
trotzt einer wesentlichen Verbesserung der Körpermotorik, eine signifikante
Verschlechterung des subjektiv und objektiv wahrgenommenen Sprecheindrucks
bewirkte. Auffällig war hierbei der gleichzeitig messbare Rückgang mehrerer
dysarthrischer Einzelsymptomen, die als typisch für Patienten mit M. Parkinson
gelten. So kam es zu einer Reduktion von Sprechpausen und bei der Hälfte der
Patienten zu einem kompletten, videostroboskopisch nachweisbaren Rückgang an
Stimmtremor. Die gleichzeitige Induktion von Sprechstörungen schien diesen
Effekten jedoch entgegen zu wirken. Diesbezüglich traten überwiegend Störungen
komplexer Sprechfunktionen auf, die sich als vermehrte Monotonie, Heiserkeit
und Sprechverlangsamung manifestierten. Insgesamt lieferte die Studie Hinweise
auf Unterschiede in der Organisation und Funktion der Sprech- und
Körpermotorik, die für die Entwicklung von Dysarthrie entscheidend sei können.
Weiterhin ist zu erwähnen, dass die Verschlechterung des Gesamteindrucks unter
der DBS des STN vor allem Patienten mit nur gering ausgeprägter vorbestehender
Dysarthrie betraf. Aus diesem Grunde sollte das Risiko der Dysarthrie bei der
Therapieplanung und Durchführung von DBS des STN besonders berücksichtigt
werden.Movement disorders frequently cause speech impairments also known as
dysarthrias. Since these result in limitation of communication they can lead
to far-reaching consequences on patients´ social lives. In patients suffering
from Parkinson´s disease (PD) a lack of dopamine primarily leads to a
dysfunction of the basal ganglia which eventually yields heavy disorders of
movement patterns. Regarding speech the typical body symptoms correlate with
monotony, imprecise articulation, hypophonia and a rough voice. Deep Brain
Stimulation (DBS) has been established as a highly effective adjuvant therapy
for patients with advanced Parkinson's disease. In this procedure electrodes
are implanted stereotactically into the subthalamic nucleus (STN), a
substructure of the basal ganglia. It is assumed that DBS STN works via an
inhibition of this pathologically hyperactive nucleus. Despite remarkable
therapeutic effects on the cardinal symptoms of PD the impact of DBS STN on
speech motor function remains controversial. Up to now both improvement and
deterioration of speech have been reported. In the present study we examined
the influence of uni- and bilateral DBS STN on the speech of 19 patients with
PD. For the realisation of a mode of speech that is perceived as healthy a
complex interaction of single speech motor subfunctions is required.
Therefore, perceptive as well as technical methodes are generally used for
dysarthria examination. In our study we focussed on the patients self-
evaluation and on an extensive external evaluation performed by speech
language pathologists. The additional technichal examinations comprised of a
number of standard procedures such as laryngeal videostroboscopy, voice range
profile, electroglottography (EGG), computerised analysis of a sustained vowel
and the analysis of the maximum phonation time. We demonstrated that DBS STN,
inspite of a crucial improvement of body symptoms, brought about a significant
worsening of the subjectively and objectively perceived impression of speech.
Strikingly, at the same time there was a measurable reduction of various
dysarthric symptoms which are considered typical for patients with PD. In this
respect speech pauses were reduced and half of the patients showed a complete
videostroboscopically-detectable decrease of voice tremor. But the
simultanious induction of speech impairments seemed to counteract these
effects. As to that, impairments of complex speech functions predominantly
occured and manifested themselves in increased montony, hoarseness and a
slowing of speech. On the whole the study gave hints on differences in the
orangisation and function of the speech and body motor system which can be
crucial for the development of dysarthria. Furthermore it is to be mentioned
that the deterioration of the overall speech impression under DBS STN mainly
affected patients with only minor preexisting dysarthria. For this reason the
risk of dysarthria should be considered whilst the planning and implementation
of DBS STN in particular
Effects of Deep Brain Stimulation on Subcortical Language Functions
No full textHintergrund: Der menschlichen Sprache liegen hochkomplexe Interaktionen diverser Hirnstrukturen zugrunde. Bei unterschiedlichen neurologischen und psychiatrischen Erkrankungen können daher Sprachstörungen auftreten. Das zunehmende Verständnis für den Netzwerkcharakter unseres Sprachsystems legt nahe, dass hieran auch subkortikale Strukturen beteiligt sind. Jedoch sind die subkortikalen Kerngebiete aufgrund ihrer Lage und Größe bisher wenig untersucht. Gleichzeitig gewinnen subkortikale Strukturen zunehmend an Bedeutung als Ziele der tiefen Hirnstimulation (Deep Brain Stimulation, DBS). So stellt die DBS im Nucleus subthalamicus (STN) bzw. im thalamischen Nucleus ventralis intermedius (VIM) etablierte Verfahren zur Behandlung therapieresistenter, motorischer Symptome bei Menschen mit Morbus Parkinson bzw. essentiellem Tremor dar. Ob die STN-DBS oder VIM-DBS neben den erwünschten Wirkungen auf die Motorik auch Effekte auf Sprachfunktionen ausübt, ist derzeit unklar.
Fragestellung: Ziel unserer Studien war die Charakterisierung potenzieller Effekte der STN-DBS und VIM-DBS auf die Sprache, um zur weiteren Therapieoptimierung beizutragen und die Konzepte subkortikaler Sprachfunktionen zu erweitern. Spezifisch interessierten uns Stimulationseffekte auf die Wortflüssigkeit und die Spontansprache sowie Bezüge zu Stimulationsparametern inkl. dem aktivierten Gewebevolumen (volume of tissue activated, VAT).
Methoden: Wir untersuchten die semantische und phonematische Wortflüssigkeit von 21 (4 weiblich) Personen mit M. Parkinson und STN-DBS im Vergleich zwischen aktivierter („ON“) und inaktivierter („OFF“) Stimulation sowie im Vergleich zu 26 (13 weiblich) Personen mit M. Parkinson ohne STN-DBS und 19 (7 weiblich) Kontrollpersonen. Ergänzend führten die Teilnehmenden lexikalische Entscheidungsaufgaben mit semantischem und phonematischem Priming durch. Ebenso untersuchten wir die Wortflüssigkeit von 13 (7 weiblich) Personen mit essentiellem Tremor und VIM-DBS im ON-OFF-Vergleich.
Die relevanten ON-OFF-Differenzen der Wortflüssigkeit von 14 (3 weiblich) Personen mit Morbus Parkinson und STN-DBS sowie bei 12 (7 weiblich) Personen mit essentiellem Tremor und VIM-DBS bezogen wir auf die Stimulationsparameter und die Elektrodenlage.
Zusätzlich untersuchten wir bei 13 Personen (8 weiblich) mit essentiellem Tremor und VIM-DBS Stimulationseffekte auf die Mikrostruktur der Wortflüssigkeit, in Form zeitlicher Cluster-und-Switch-Analysen, die wir ebenfalls auf die Stimulationsparameter und die Elektrodenlage bezogen.
Um mögliche Stimulationseffekte auf die Alltagssprache zu beurteilen, untersuchten wir zudem die Spontansprache anhand semistrukturierter Interviews von 14 (3 weiblich) Personen mit M. Parkinson und STN-DBS sowie 13 (6 weiblich) Personen mit essentiellem Tremor und VIM-DBS im ON-OFF-Vergleich. Die linguistischen Analysen umfassten die lexikalische Semantik, Morphologie, Syntax, Stilmittel, Fehler, Wort- und Satzproduktionsraten, Pausen, Wortdiversität, Wortklassen und Satzkomplexität. Relevante ON-OFF-Differenzen der Personen mit STN-DBS bezogen wir auf das VAT.
Ergebnisse: Unabhängig vom Stimulationszustand (ON versus OFF) produzierten Personen mit STN-DBS deutlich weniger Wörter als Gesunde oder Personen mit M. Parkinson ohne STN-DBS und reagierten langsamer in den lexikalischen Entscheidungsaufgaben, wobei semantische und phonematische Priming-Effekte erhalten blieben. Allerdings nahm die phonematische Wortflüssigkeit im ON leicht zu. Dies war mit einer weiter anteromedialen Elektrodenlokalisation im linken STN und höheren Stimulationsamplituden assoziiert. Zudem machten die Personen bei der Spontansprache im ON weniger Fehler und produzierten mehr Wörter und Sätze. Diese Zunahme korrelierte mit dem VAT im assoziativen STN-Anteil.
Bei Menschen mit essentiellem Tremor und VIM-DBS führte die Stimulation zu einer signifikanten Reduktion der Wortflüssigkeit. Die Cluster-und-Switch-Analyse ergab eine zugrunde liegende Verlängerung der Intraclusterzeit, definiert als Zeitintervalle zwischen den Wörtern innerhalb eines Clusters. Diese Effekte waren mit einer weiter anteroventromedialen Elektrodenlage und höheren Stimulationsamplituden assoziiert. Außerdem bildeten die Personen mit VIM-DBS im ON versus OFF weniger Nebensätze im Sinne einer vereinfachten grammatikalischen Satzstruktur.
Sämtliche Stimulationseffekte auf Sprachfunktionen waren unabhängig von Effekten auf die Motorik. Geschlechtsabhängige Unterschiede fanden wir nicht.
Diskussion und Schlussfolgerung: Unsere Ergebnisse unterstützen die Annahme, dass einzelne Kerne der Basalganglien bzw. des Thalamus‘ an differenzierbaren Sprachfunktionen beteiligt sind und zeigen, dass die DBS im STN bzw. VIM Wirkungen auf Sprachfunktionen ausüben kann. In beiden Fällen suggerieren die Lokalisationsdaten, dass diese Effekte nicht unmittelbar innerhalb der DBS-Zielstruktur entstehen, sondern in angrenzenden Nachbarstrukturen.
Hierbei scheint STN-DBS positive Effekte auf Sprachfunktionen ausüben zu können. So könnte eine Mitstimulation des assoziativen STN-Anteils bei einer eher anteromedialen Elektrodenlage im motorischen STN-Anteil die Wort- und Satzproduktion erleichtern und damit Dopaminmangel bedingten Sprachstörungen entgegenwirken. Dies kann als eine Flexibilisierung fronto-basalganglionärer Netzwerke verstanden werden. Den sprachflussfördernden Stimulationseffekten steht die vermutlich implantationsbedingte Abnahme der Wortflüssigkeit gegenüber.
Die Stimulation im VIM führte dagegen zu einer signifikanten Reduktion der Wortflüssigkeit mit einer spezifischen Verlangsamung der automatischen Wortaktivierung. Ursächlich schien eine Mitstimulation des thalamischen Nucleus ventralis lateralis anterior (VLa) und möglicherweise auch des Nucleus ventralis anterior (VA) zu sein, für die Interaktionen mit dem Broca-Areal postuliert wurden. Zudem war unter aktiver VIM-DBS die grammatikalische Satzkomplexität reduziert. Angesichts ähnlicher Befunde nach thalamischen Infarkten ist auch hier eine Störung der Interaktion zwischen dem VA und dem Broca-Areal vorstellbar.
Bei der klinischen Planung der DBS und in künftigen Studien sollten individuelle Faktoren wie das kognitive und sprachliche Ausgangsniveau sowie die Stimulationsparameter und exakte Elektrodenlokalisation berücksichtigt werden.Background: Human language is based on highly complex interactions between various brain structures. Language disorders can therefore occur in various neurological and psychiatric diseases. The increasing understanding of the network character of our language system suggests that subcortical structures are also involved. However, due to their location and size, subcortical nuclei have been little studied to date. At the same time, subcortical structures are becoming increasingly important as targets for deep brain stimulation (DBS). DBS of the subthalamic nucleus (STN) and the thalamic ventral intermediate nucleus (VIM) are established options for the treatment of therapy-resistant motor symptoms in persons with Parkinson's disease (PD) or essential tremor (ET). Whether STN-DBS or VIM-DBS also has effects on language functions in addition to the desired effects on motor function is currently unclear.
Objective: The aim of our studies was to characterize the potential effects of STN-DBS and VIM-DBS on language in order to contribute to further therapy optimisation and to expand the concepts of subcortical language functions. Specifically, we were interested in stimulation effects on verbal fluency and spontaneous language as well as relations to stimulation parameters including the volume of tissue activated (VAT).
Methods: We examined semantic and phonemic verbal fluency scores of 21 (4 female) persons with PD and STN-DBS in comparison between activated (“ON”) and inactivated (“OFF”) stimulation and in comparison to 26 (13 female) persons with PD without STN-DBS and 19 (7 female) healthy controls. In addition, the participants performed lexical decision tasks with semantic and phonemic priming. We also examined verbal fluency scores of 13 (7 female) persons with ET and VIM-DBS in their ON versus OFF stimulation condition.
We related the relevant ON-OFF differences in verbal fluency scores of 14 (3 female) individuals with PD and STN-DBS and 12 (7 female) individuals with ET and VIM-DBS to the stimulation parameters and electrode position.
In addition, we investigated stimulation effects on the microstructure of verbal fluency in 13 persons (8 female) with ET and VIM-DBS, in the form of temporal cluster-and-switch analyses, which we also related to stimulation parameters and electrode localisation.
To assess possible stimulation effects on everyday language, we also examined spontaneous language samples using semi-structured interviews of 14 (3 female) individuals with PD and STN-DBS and 13 (6 female) individuals with ET and VIM-DBS in an ON-OFF comparison. The linguistic analyses included lexical semantics, morphology, syntax, stylistic devices, errors, word and sentence production rates, pauses, word diversity, word classes and sentence complexity. We related relevant ON-OFF differences of individuals with STN-DBS to their individual VAT.
Results: Regardless of stimulation condition (ON versus OFF), individuals with STN-DBS produced significantly fewer words than healthy individuals or individuals with PD without STN-DBS and responded more slowly in the lexical decision tasks, although semantic and phonemic priming effects were preserved. However, phonemic verbal fluency increased slightly in the ON condition. This was associated with a more anteromedial electrode localisation in the left STN and higher stimulation amplitudes. In addition, the individuals made fewer errors during spontaneous language in the ON condition and produced more words and clauses. This increase correlated with the VAT in the associative part of the STN.
In persons with ET and VIM-DBS, stimulation led to a significant reduction in verbal fluency rates. Cluster-and-switch analysis revealed an underlying increase in intracluster time, defined as time intervals between words within a cluster. These effects were associated with a more anteroventromedial electrode localisation and higher stimulation amplitudes. In addition, individuals with VIM-DBS in their ON versus OFF condition used fewer subordinate clauses, i.e. a simplified syntactic sentence structure.
All stimulation effects on language functions were independent from effects on motor functions. We did not find any gender-dependent differences.
Discussion and conclusion: Our results support the assumption that individual nuclei of the basal ganglia and the thalamus are involved in differentiable language functions and show that DBS in the STN and VIM can exert effects on language functions. In both cases, the localisation data suggest that these effects do not arise directly within the DBS target structure, but in adjacent neighbouring structures.
STN-DBS appears to be able to exert positive effects on language functions. With a more anteromedial electrode position in the motor STN, co-stimulation of the associative part of the STN could facilitate word and sentence production, thus counteracting language disorders related to dopamine deficiency. This can be understood as a flexibilisation of fronto-basal-ganglia networks. The fluency-enhancing stimulation effects are offset by the presumably implantation-related decrease in verbal fluency.
Stimulation in the VIM, on the other hand, led to a significant reduction in verbal fluency with a specific slowing of automatic word activation. This appeared to be caused by co-stimulation of the thalamic ventral lateral anterior nucleus (VLa) and possibly also the ventral anterior nucleus (VA), for which interactions with Broca's area have been postulated. In addition, syntactic sentence complexity was reduced under active VIM-DBS. In view of similar findings after thalamic infarction, a disturbance of the interaction between the VA and Broca's area is also conceivable here. In the clinical planning of DBS and in future studies, individual factors such as the pre-operative cognitive and linguistic status as well as the stimulation parameters and exact electrode localisation should be taken into account
"Kometensplitter einer Biographie" & die vielstimmige Beweglichkeit der Kunst. Autofiktionales Erzählen in Felicitas HOPPEs Hoppe
No full textIn this thesis I examine in how far, or to which degree, the concept of autofiction can be
applied to Felicitas Hoppe’s text Hoppe (2012). Since the coinage of the term
‘autofiction’ by Serge Doubrovsky in the 1970s, there have been many discussions and
redefinitions of this possible genre. The discussions include questions regarding
definitions of autobiography and the novel within the field of literary theory, as well as
the depiction of fact and fiction. Moreover, they ask in how far the knowledge of the
impossibility of capturing ‘reality’ via language technically turns any autobiography
into autofiction. Various positions regarding these debates, including the thoughts and
positions of scholars such as Philippe Lejeune, Serge Doubrovsky, Martina Wagner-
Egelhaaf, and Frank Zipfel, are represented in the first part of this thesis.
In the sections that follow, I show how Felicitas Hoppe’s Hoppe is a text that
intertwines ‘factuality’ and ‘fiction’ in a way that it can be interpreted as either or
indeed simultaneously both genres (doppeltes Leseangebot) in the sense of Frank
Zipfel. I point out that from the paratextual features of Hoppe to the tripartite fission of
‘Hoppe’ – including the author HOPPE, the narrator ‘fh’, and the protagonist Felicitas
Hoppe – the text allows and asks with its particular construction for new interpretations
of identity and self-representation.
Finally, I conclude with the assumption that Hoppe is a text that might not be
completely captured with present available literary theories. However, the refusal of the
text to being fully assigned to any one particular genre or typology remains one of the
many strengths of Felicitas Hoppe’s Hoppe
Potential and limitations of organic and fair trade cotton for improving livelihoods of smallholders: evidence from Central Asia
No full textCotton is a leading agricultural non-food commodity associated with soil degradation, water pollution and pesticide poisoning due to high levels of agrochemical inputs. Organic farming is often promoted as a means of addressing the economic, environmental and health risks of conventional cotton production, and it is slowly gaining ground in the global cotton market. Organic and fair trade cotton are widely seen as opportunities for smallholder farmers to improve their livelihoods thanks to higher returns, lower input costs and fewer risks. Despite an increasing number of studies comparing the profitability of organic and non-organic farming systems in developing and industrialized countries, little has been published on organic farming in Central Asia. The aim of this article is to describe the economic performance and perceived social and environmental impacts of organic cotton in southern Kyrgyzstan, drawing on a comparative field study conducted by the author in 2009. In addition to economic and environmental aspects, the study investigated farmers’ motivations toward and assessment of conversion to organic farming. Cotton yields on organic farms were found to be 10% lower, while input costs per unit were 42% lower; as a result, organic farmers’ cotton revenues were 20% higher. Due to lower input costs as well as organic and fair trade price premiums, the average gross margin from organic cotton was 27% higher. In addition to direct economic benefits, organic farmers enjoy other benefits, such as easy access to credit on favorable terms, provision of uncontaminated cottonseed cooking oil and cottonseed cake as animal feed, and marketing support as well as extension and training services provided by newly established organic service providers. The majority of organic farmers perceive improved soil quality, improved health conditions, and positively assess their initial decision to convert to organic farming. The major disadvantage of organic farming is the high manual labor input required. In the study area, where manual farm work is mainly women's work and male labor migration is widespread, women are most affected by this negative aspect of organic farming. Altogether, the results suggest that, despite the inconvenience of a higher workload, the advantages of organic farming outweigh its disadvantages and that conversion to organic farming improves the livelihoods of small-scale farmers
A Vector Space Model for Neural Network Functions: Inspirations From Similarities Between the Theory of Connectivity and the Logarithmic Time Course of Word Production
No full textThe present report examines the coinciding results of two study groups each presenting a power-of-two function to describe network structures underlying perceptual processes in one case and word production during verbal fluency tasks in the other. The former is theorized as neural cliques organized according to the functionN= 2(i)- 1, whereas the latter assumes word conglomerations thinkable as tuples following the functionN= 2(i). Both theories assume the innate optimization of energy efficiency to cause the specific connectivity structure. The vast resemblance between both formulae motivated the development of a common formulation. This was obtained by using a vector space model, in which the configuration of neural cliques or connected words is represented by aN-dimensional state vector. A further analysis of the model showed that the entire time course of word production could be derived using basically one single minimal transformation-matrix. This again seems in line with the principle of maximum energy efficiency
Age-related dissociation of N400 effect and lexical priming
No full textThe use of contextual information is an important capability to facilitate language comprehension. This can be shown by studying behavioral and neurophysiological measures of accelerated word recognition when semantically or phonemically related information is provided in advance, resulting in accompanying attenuation of the respective event-related potential, i.e. the N400 effect. Against the background of age-dependent changes in a broad variety of lexical capacities, we aimed to study whether word priming is accomplished differently in elderly compared to young persons. 19 young (29.9 ± 5.6 years) and 15 older (69.0 ± 7.2 years) healthy adults participated in a primed lexical decision task that required the classification of target stimuli (words or pseudo-words) following related or unrelated prime words. We assessed reaction time, task accuracy and N400 responses. Acceleration of word recognition by semantic and phonemic priming was significant in both groups, but resulted in overall larger priming effects in the older participants. Compared with young adults, the older participants were slower and less accurate in responding to unrelated word-pairs. The expected N400 effect was smaller in older than young adults, particularly during phonemic word and pseudo-word priming, with a rather similar N400 amplitude reduction by semantic relatedness. The observed pattern of results is consistent with preserved or even enhanced lexical context sensitivity in older compared to young adults. This, however, appears to involve compensatory cognitive strategies with higher lexical processing costs during phonological processing in particular, suggested by a reduced N400 effect in the elderly
Dopamine-Related Reduction of Semantic Spreading Activation in Patients With Parkinson’s Disease
No full textImpaired performance in verbal fluency (VF) tasks is a frequent observation in Parkinson's disease (PD). As to the nature of the underlying cognitive deficit, it is commonly attributed to a frontal-type dysexecutive syndrome due to nigrostriatal dopamine depletion. Whereas dopaminergic medication typically improves VF performance in PD, e.g., by ameliorating impaired lexical switching, its effect on semantic network activation is unclear. Data from priming studies suggest that dopamine causes a faster decay of semantic activation spread. The aim of the current study was to examine the impact of dopaminergic medication on the dynamic change of word frequency during VF performance as a measure of semantic spreading activation. To this end, we performed a median split analysis of word frequency during phonemic and semantic VF task performance in a PD group tested while receiving dopaminergic medication (ON) as well as after drug withdrawal (i.e., OFF), and in a sample of age-matched healthy volunteers (both groups n = 26). Dopaminergic medication in the PD group significantly affected phonemic VF with improved word production as well as increased error-rates. The expected decrease of word frequency during VF task performance was significantly smaller in the PD group ON medication than in healthy volunteers across semantic and phonemic VF. No significant group-difference emerged between controls and the PD group in the OFF condition. The comparison between both treatment conditions within the PD group did not reach statistical significance. The observed pattern of results indicates a faster decay of semantic network activation during lexical access in PD patients on dopaminergic medication. In view of improved word generation, this finding is consistent with a concept of more focused neural activity by an increased signal-to-noise ratio due to dopaminergic neuromodulation. However, the effect of dopaminergic stimulation on VF output suggests a trade-off between these beneficial effects and increased error-rates
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