Fabio Richlan | University of Salzburg (original) (raw)

Papers by Fabio Richlan

Cloze enough? Hemodynamic effects of predictive processing during natural reading. , 2021

Evidence accrues that readers form multiple hypotheses about upcoming words. The present study in... more Evidence accrues that readers form multiple hypotheses about upcoming words. The present study investigated the hemodynamic effects of predictive processing during natural reading by means of combining fMRI and eye movement recordings. In particular, we investigated the neural and behavioral correlates of precision-weighted prediction errors, which are thought to be indicative of subsequent belief updating. Participants silently read sentences in which we manipulated the cloze probability and the semantic congruency of the final word that served as an index for precision and prediction error respectively. With respect to the neural correlates, our findings indicate an enhanced activation within the left inferior frontal and middle temporal gyrus suggesting an effect of precision on prediction update in higher (lexico-)semantic levels. Despite being evident at the neural level, we did not observe any evidence that this mechanism resulted in disproportionate reading times on participants' eye movements. The results speak against discrete predictions, but favor the notion that multiple words are activated in parallel during reading.

OSFPREPRINTS, 2023

Note: this version is a preprint. The final version will appear in 'Methods for analyzing large n... more Note: this version is a preprint. The final version will appear in 'Methods for analyzing large neuroimaging datasets' to be published as part of Springer Nature's Neuromethods series. The published version of this chapter will contain links to other chapters, to a glossary and to a list of resources.

Royal Society Open Science, 2021

Humans grossly underestimate exponential growth, but areat the same time overconfident in their (... more Humans grossly underestimate exponential growth, but areat the same time overconfident in their (poor) judgement.The so-called‘exponential growth bias’is of new relevancein the context of COVID-19, because it explains whyhumans have fundamental difficulties to grasp themagnitude of a spreading epidemic. Here, we addressedthe question, whether logarithmic scaling and contextualframing of epidemiological data affect the anticipation ofexponential growth. Our findings show that underestimationswere most pronounced when growth curves were linearlyscaledandframed in the context of a more advancedepidemic progression. For logarithmic scaling, estimates weremuch more accurate, on target for growth rates around 31%,and not affected by contextual framing. We conclude that thelogarithmic depiction is conducive for detecting exponentialgrowth during an early phase as well as resurgences ofexponential growth

Word length, frequency, and predictability count among the most influential variables during read... more Word length, frequency, and predictability count among the most influential variables during reading. Their effects are well-documented in eye movement studies, but pertinent evidence from neuroimaging primarily stem from single-word presentations. We investigated the effects of these variables during reading of whole sentences with simultaneous eye-tracking and functional magnetic resonance imaging (fixation-related fMRI). Increasing word length was associated with increasing activation in occipital areas linked to visual analysis. Additionally, length elicited a U-shaped modulation (i.e., least activation for medium-length words) within a brain stem region presumably linked to eye movement control. These effects, however, were diminished when accounting for multiple fixation cases. Increasing frequency was associated with decreasing activation within left inferior frontal, superior parietal, and occipito-temporal regions. The function of the latter region—hosting the putative visual word form area—was originally considered as limited to sublexical processing. An exploratory analysis revealed that increasing predictability was associated with decreasing activation within middle temporal and inferior frontal regions previously implicated in memory access and unification. The findings are discussed with regard to their correspondence with findings from single-word presentations and with regard to neurocognitive models of visual word recognition, semantic processing, and eye movement control during reading.

The present study investigated oscillatory brain dynamics during self-paced sentence-level proces... more The present study investigated oscillatory brain dynamics during self-paced sentence-level processing. Participants read fully correct sentences, sentences containing a semantic violation and " sentences " in which the order of the words was randomized. At the target word level, fixations on semantically unrelated words elicited a lower-beta band (13–18 Hz) desynchronization. At the sentence level, gamma power (31–55 Hz) increased linearly for syntactically correct sentences, but not when the order of the words was randomized. In the 300–900 ms time window after sentence onsets, theta power (4–7 Hz) was greater for syntactically correct sentences as compared to sentences where no syntactic structure was preserved (random words condition). We interpret our results as conforming with a recently formulated predictive-coding framework for oscillatory neural dynamics during sentence-level language comprehension. Additionally, we discuss how our results relate to previous findings with serial visual presentation vs. self-paced reading.

We examined the evidence from functional imaging studies for predominance of a phonological left ... more We examined the evidence from functional imaging studies for predominance of a phonological left temporo-parietal (TP) dysfunction in dyslexic children and predominance of a visual-orthographic left occipito-temporal (OT) dysfunction in dyslexic adults. Separate meta-analyses of 9 studies with children (age means: 9-11 years) and of 9 studies with adults (age means: 18-30 years) and statistical comparison of these meta-analytic maps did find support for a dysfunction of a left ventral OT region in both children and adults. The findings on a possible predominance of a left TP dysfunction in children were inconclusive. Contrary to expectation, underactivation in superior temporal regions was only found for adults, but not for children. For children, underactivation was found in bilateral inferior parietal regions, but this abnormality was no longer present when foci identified by higher dyslexic task-negative activation (i.e., deactivation in response to reading compared to baseline) were excluded.

Neuroscience & Biobehavioral Reviews, 2014

The present fMRI study investigated the effects of word-likeness of visual and auditory stimuli o... more The present fMRI study investigated the effects of word-likeness of visual and auditory stimuli on activity along the ventral visual stream. In the context of a one-back task, we presented visual and auditory words, pseudowords, and artificial stimuli (i.e., false-fonts and reversed-speech, respectively). Main findings were regionally specific effects of word-likeness on activation in a left ventral occipitotemporal region corresponding to the classic localization of the Visual Word Form Area (VWFA). Specifically, we found an inverse word-likeness effect for the visual stimuli in the form of decreased activation for words compared to pseudowords which, in turn, elicited decreased activation compared to the artificial stimuli. For the auditory stimuli, we found positive word-likeness effects as both words and pseudowords elicited more activation than the artificial stimuli. This resulted from a marked deactivation in response to the artificial stimuli and no such deactivation for words and pseudowords. We suggest that the opposite effects of visual and auditory word-likeness on VWFA activation can be explained by assuming the involvement of visual orthographic memory representations. For the visual stimuli, these representations reduce the coding effort as a function of word-likeness. This results in highest activation to the artificial stimuli and least activation to words for which corresponding representations exist. The positive auditory word-likeness effects may result from activation of orthographic information associated with the auditory words and pseudowords. The view that the VWFA has a primarily visual function is supported by our findings of high activation to the visual artificial stimuli (which have no phonological or semantic associations) and deactivation to the auditory artificial stimuli. According to the phenomenon of cross-modal sensory suppression such deactivations during demanding auditory processing are expected in visual regions.

The present study investigated the feasibility of using self-paced eye movements during reading (... more The present study investigated the feasibility of using self-paced eye movements during reading (measured by an eye tracker) as markers for calculating hemodynamic brain responses measured by functional magnetic resonance imaging (fMRI). Specifically, we were interested in whether the fixation-related fMRI analysis approach was sensitive enough to detect activation differences between reading material (words and pseudowords) and nonreading material (line and unfamiliar Hebrew strings). Reliable reading-related activation was identified in left hemisphere superior temporal, middle temporal, and occipito-temporal regions including the visual word form area (VWFA). The results of the present study are encouraging insofar as fixation-related analysis could be used in future fMRI studies to clarify some of the inconsistent findings in the literature regarding the VWFA. Our study is the first step in investigating specific visual word recognition processes during self-paced natural sentence reading via simultaneous eye tracking and fMRI, thus aiming at an ecologically valid measurement of reading processes. We provided the proof of concept and methodological framework for the analysis of fixation-related fMRI activation in the domain of reading research.

The boundary paradigm, in combination with parafoveal masks, is the main technique for studying p... more The boundary paradigm, in combination with parafoveal masks, is the main technique for studying parafoveal preprocessing during reading. The rationale is that the masks (e.g., strings of X's) prevent parafoveal preprocessing, but do not interfere with foveal processing. A recent study, however, raised doubts about the neutrality of parafoveal masks. In the present study, we explored this issue by means of fixation-related brain potentials (FRPs). Two FRP conditions presented rows of five words. The task of the participant was to judge whether the final word of a list was a "new" word, or whether it was a repeated (i.e., "old") word. The critical manipulation was that the final word was X-masked during parafoveal preview in one condition, whereas another condition presented a valid preview of the word. In two additional event-related brain potential (ERP) conditions, the words were presented serially with no parafoveal preview available; in one of the conditions with a fixed timing, in the other word presentation was self-paced by the participants. Expectedly, the valid-preview FRP condition elicited the shortest processing times. Processing times did not differ between the two ERP conditions indicating that "cognitive readiness" during self-paced processing can be ruled out as an alternative explanation for differences in processing times between the ERP and the FRP conditions. The longest processing times were found in the X-mask FRP condition indicating that parafoveal X-masks interfere with foveal word recognition.

Approaches using eye movements as markers of ongoing brain activity to investigate perceptual and... more Approaches using eye movements as markers of ongoing brain activity to investigate perceptual and cognitive processes were able to implement highly sophisticated paradigms driven by eye movement recordings. Crucially, these paradigms involve display changes that have to occur during the time of saccadic blindness, when the subject is unaware of the change. Therefore, a combination of high-speed eye tracking and high-speed visual stimulation is required in these paradigms. For combined eye movement and brain activity studies (e.g., fMRI, EEG, MEG), fast and exact timing of display changes is especially important, because of the high susceptibility of the brain to visual stimulation. Eye tracking systems already achieve sampling rates up to 2000 Hz, but recent LCD technologies for computer screens reduced the temporal resolution to mostly 60 Hz, which is too slow for gaze-contingent display changes. We developed a high-speed video projection system, which is capable of reliably delivering display changes within the time frame of < 5 ms. This could not be achieved even with the fastest cathode ray tube (CRT) monitors available (< 16 ms). The present video projection system facilitates the realization of cutting-edge eye movement research requiring reliable high-speed visual stimulation (e.g., gaze-contingent display changes, short-time presentation, masked priming). Moreover, this system can be used for fast visual presentation in order to assess brain activity using various methods, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). The latter technique was previously excluded from high-speed visual stimulation, because it is not possible to operate conventional CRT monitors in the strong magnetic field of an MRI scanner. Therefore, the present video projection system offers new possibilities for studying eye movement-related brain activity using a combination of eye tracking and fMRI.

Journal of Cognitive Neuroscience, 2009

This fMRI study contrasted case-deviant and letter-deviant forms with familiar forms of the same ... more This fMRI study contrasted case-deviant and letter-deviant forms with familiar forms of the same
phonological words (e.g., TaXi and Taksi vs. Taxi) and found, that both types of deviance led to
increased activation in a left occipitotemporal region corresponding to the Visual Word Form
Area. Case-deviant items, in addition, led to increased activation in a right occipitotemporal region
and in a left occipital and a left posterior occipitotemporal region, possibly reflecting the increased
demands on letter form coding. For letter-deviant items, in addition to the increased left
occipitotemporal activation, a main finding was increased activation primarily in extended left
frontal regions, possibly reflecting sublexically mediated access to word phonology. These
findings are consistent with general features of cognitive dual-route models of visual word
processing. Furthermore, they add support to the main feature of Dehaene et al.’s (2005) neural
model of early stages of visual word processing . However, the increased activation found for
case-deviant items in the VWFA cannot be immediately reconciled with the assumption of
completely abstract case-independent orthographic word codes in the VWFA.

Cerebral cortex (New York, N.Y. : 1991), Jan 28, 2014

Reading requires the interaction between multiple cognitive processes situated in distant brain a... more Reading requires the interaction between multiple cognitive processes situated in distant brain areas. This makes the study of functional brain connectivity highly relevant for understanding developmental dyslexia. We used seed-voxel correlation mapping to analyse connectivity in a left-hemispheric network for task-based and resting-state fMRI data. Our main finding was reduced connectivity in dyslexic readers between left posterior temporal areas (fusiform, inferior temporal, middle temporal, superior temporal) and the left inferior frontal gyrus. Reduced connectivity in these networks was consistently present for 2 reading-related tasks and for the resting state, showing a permanent disruption which is also present in the absence of explicit task demands and potential group differences in performance. Furthermore, we found that connectivity between multiple reading-related areas and areas of the default mode network, in particular the precuneus, was stronger in dyslexic compared w...

Human Brain Mapping, 2009

This study used foci from 17 original studies on functional abnormalities in the dyslexic brain t... more This study used foci from 17 original studies on functional abnormalities in the dyslexic brain to identify brain regions with consistent under- or overactivation. Studies were included when reading or reading-related tasks were performed on visually presented stimuli and when results reported coordinates for group differences. Activation Likelihood Estimation (ALE) was used for quantification. Maxima of underactivation were found in inferior parietal, superior temporal, middle and inferior temporal and fusiform regions of the left hemisphere. With respect to left frontal abnormalities we found underactivation in the inferior frontal gyrus to be accompanied by overactivation in the primary motor cortex and the anterior insula. Tentative functional interpretations of the activation abnormalities are provided.

Cortex, 2010

This study examined functional brain abnormalities in dyslexic German readers who e due to the re... more This study examined functional brain abnormalities in dyslexic German readers who e due to the regularity of German in the reading direction e do not exhibit the reading accuracy problem of English dyslexic readers, but suffer primarily from a reading speed problem. The in-scanner task required phonological lexical decisions (i.e., Does xxx sound like an existing word?) and presented familiar and unfamiliar letter strings of existing phonological words (e.g., Taxi-Taksi) together with nonwords (e.g., Tazi). Dyslexic readers exhibited the same response latency pattern (words < pseudohomophones < nonwords) as nonimpaired readers, but latencies to all item types were much prolonged. The imaging results were suggestive for a different neural organization of reading processes in dyslexic readers. Specifically, dyslexic readers, in response to lexical route processes, exhibited underactivation in a left ventral occipitotemporal (OT) region which presumably is engaged by visual-orthographic whole word recognition. This region was also insensitive to the increased visual-orthographic processing demands of the sublexical route. Reduced engagement in response to sublexical route processes was also found in a left inferior parietal region, presumably engaged by attentional processes, and in a left inferior frontal region, presumably engaged by phonological processes. In contrast to this reduced n engagement of the optimal left hemisphere reading network (ventral OT, inferior parietal, inferior frontal), our dyslexic readers exhibited increased engagement of visual occipital regions and of regions presumably engaged by silent articulatory processes (premotor/ motor cortex and subcortical caudate and putamen).

PLoS ONE, 2010

Background: We used fMRI to examine functional brain abnormalities of German-speaking dyslexics w... more Background: We used fMRI to examine functional brain abnormalities of German-speaking dyslexics who suffer from slow effortful reading but not from a reading accuracy problem. Similar to acquired cases of letter-by-letter reading, the developmental cases exhibited an abnormal strong effect of length (i.e., number of letters) on response time for words and pseudowords. Results: Corresponding to lesions of left occipito temporal (OT) regions in acquired cases, we found a dysfunction of this region in our developmental cases who failed to exhibit responsiveness of left OT regions to the length of words and pseudowords. This abnormality in the left OT cortex was accompanied by absent responsiveness to increased sublexical reading demands in phonological inferior frontal gyrus (IFG) regions. Interestingly, there was no abnormality in the left superior temporal cortex which—corresponding to the onological deficit explanation—is considered to be the prime locus of the reading difficulties of developmental dyslexia cases. Conclusions: The present functional imaging results suggest that developmental dyslexia similar to acquired letter-by-letter reading is due to a primary dysfunction of left OT regions.

NeuroImage, 2010

Based on our previous work, we expected the Visual Word Form Area (VWFA) in the left ventral visu... more Based on our previous work, we expected the Visual Word Form Area (VWFA) in the left ventral visual pathway to be engaged by both whole-word recognition and by serial sublexical coding of letter strings. To examine this double function, a phonological lexical decision task (i.e., “Does xxx sound like an existing word?”) presented short and long letter strings of words, pseudohomophones, and pseudowords (e.g., Taxi, Taksi and Tazi). Main findings were that the length effect for words was limited to occipital regions and absent in the VWFA. In contrast, a marked length effect for pseudowords was found throughout the ventral visual pathway including the VWFA, as well as in regions presumably engaged by visual attention and silent-articulatory processes. The length by lexicality interaction on brain activation corresponds to well-established behavioral findings of a length by lexicality interaction on naming latencies and speaks for the engagement of the VWFA by both lexical and sublexical processes.