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Biomedical subjects

Thomas Jacobsen

Publications and source records attributed to Thomas Jacobsen.

At least 19 recordsLinked to original sources
PubMed2005

Brain correlates of aesthetic judgment of beauty.

Functional MRI was used to investigate the neural correlates of aesthetic judgments of beauty of geometrical shapes. Participants performed evaluative aesthetic judgments (beautiful or not?) and descriptive symmetry judgments (symmetric or not?) on the same stimulus material. Symmetry was employed because aesthetic judgments are known to be often guided by criteria of symmetry. Novel, abstract graphic patterns were presented to minimize influences of attitudes or memory-related processes and to test effects of stimulus symmetry and complexity. Behavioral results confirmed the influence of stimulus symmetry and complexity on aesthetic judgments. Direct contrasts showed specific activations for aesthetic judgments in the frontomedian cortex (BA 9/10), bilateral prefrontal BA 45/47, and posterior cingulate, left temporal pole, and the temporoparietal junction. In contrast, symmetry judgments elicited specific activations in parietal and premotor areas subserving spatial processing. Interestingly, beautiful judgments enhanced BOLD signals not only in the frontomedian cortex, but also in the left intraparietal sulcus of the symmetry network. Moreover, stimulus complexity caused differential effects for each of the two judgment types. Findings indicate aesthetic judgments of beauty to rely on a network partially overlapping with that underlying evaluative judgments on social and moral cues and substantiate the significance of symmetry and complexity for our judgment of beauty.

Adult↗
PubMed2005

Timed action and object naming.

Factors affecting object and action naming were compared in a timed picture-naming paradigm, for drawings of 520 objects and 275 actions, named by adult native speakers of English. Massive differences between object and action naming were observed for all dependent variables, and theoretically relevant differences emerged in the variables that predict retrieval of nouns vs. verbs in this task. Matching object and action items for variables like frequency, age of acquisition, or picture complexity does not result in a match for measures of naming difficulty (name agreement or latency). Conversely, object and action items matched for naming difficulty invariably differ in their other lexical and pictorial properties. A reaction time disadvantage for action naming remains even after controlling for picture properties, target word properties, name agreement itself (reflecting the differential ambiguity of nouns and verbs) as well as a measure of conceptual or psychological complexity based on the number of relevant objects in the scene. Surprisingly, frequency effects run in opposite directions for nouns (higher frequencies yield faster RTs) and verbs (higher frequencies are associated with slower RTs, reflecting a "light verb" strategy that speakers use for difficult items). Implications for method and theory in the study of lexical access are discussed, including relevance to a growing literature on the neurobiology and development of nouns and verbs.

Adolescent↗
PubMed2005

Memory-based or afferent processes in mismatch negativity (MMN): a review of the evidence.

The mismatch negativity (MMN) is an electromagnetic response to any discriminable change in regular auditory input. This response is usually interpreted as being generated by an automatic cortical change-detection process in which a difference is found between the current input and the representation of the regular aspects of the preceding auditory input. Recently, this interpretation was questioned by Jääskeläinen et al. (2004) who proposed that the MMN is a product of an N1 (N1a) difference wave emerging in the subtraction procedure used to visualize and quantify the MMN. We now evaluate this "adaptation hypothesis" of the MMN in the light of the available data. It is shown that the MMN cannot be accounted for by differential activation of the afferent N1 transient detectors by repetitive ("standard") stimuli and deviant ("novel") stimuli and that the presence of a memory representation of the standard is required for the elicitation of MMN.

Acoustic Stimulation↗
PubMed2005

Familiarity affects the processing of task-irrelevant auditory deviance.

The effects of familiarity on auditory change detection on the basis of auditory sensory memory representations were investigated by presenting oddball sequences of sounds while participants ignored the auditory stimuli. Stimulus sequences were composed of sounds that were familiar and sounds that were made unfamiliar by playing the same sounds backward. The roles of frequently presented stimuli (standards) and infrequently presented ones (deviants) were fully crossed. Deviants elicited the mismatch negativity component of the event-related brain potential. We found an enhancement in detecting changes when deviant sounds appeared among familiar standard sounds compared when they were delivered among unfamiliar standards. Familiarity with the deviant sounds also enhanced the change-detection process. We suggest that tuning to familiar items sets up preparatory processes that affect change detection in familiar sound sequences.

Acoustic Stimulation↗
PubMed2004

Mismatch negativity to frequency changes: no evidence from human event-related brain potentials for categorical speech processing of complex tones resembling vowel formant structure.

Based on a memory-comparison process, changes in the pitch of repetitive sounds are pre-attentively detected, reflected by the mismatch negativity (MMN) event-related brain potential. In the present investigation of categorical speech perception, complex tones were used that consisted of vowel-defining F1 and F2 formant information while not being perceived as speech. MMN was obtained in oddball blocks. The auditory system tracks two simultaneous changes in formant frequencies of 50 Hz while also abstracting from three levels of intensity variation. Lower frequency deviants elicited larger MMN. No effects of language-categorical processing were observed.

Acoustic Stimulation↗
PubMed2004

Pre-attentive categorization of vowel formant structure in complex tones.

It has been demonstrated that vowel information can be extracted from speech sounds without attention focused on them, despite widely varying non-speech acoustic information in the input. The present study tested whether even complex tones that were constructed based on F0, F1 and F2 vowel frequencies to resemble the defining features of speech sounds, but were not speech, are categorized pre-attentively according to vowel space information. The Mismatch Negativity brain response was elicited by infrequent tokens of the complex tones, showing that the auditory system can pre-attentively categorize speech information on the basis of the minimal, defining auditory features. The human mind extracts the language-relevant information from complex tones despite the non-relevant variation in the sound input.

Adult↗
PubMed2004

Pre-attentive auditory processing of lexicality.

The effects of lexicality on auditory change detection based on auditory sensory memory representations were investigated by presenting oddball sequences of repeatedly presented stimuli, while participants ignored the auditory stimuli. In a cross-linguistic study of Hungarian and German participants, stimulus sequences were composed of words that were language-familiar, lexical, meaningful in Hungarian but language-unfamiliar, not lexical, meaningless in German, and words with the opposite characteristics. The roles of frequently presented stimuli (Standards) and infrequently presented one (Deviants) were fully crossed. Language-familiar and language-unfamiliar Deviants elicited the Mismatch Negativity component of the event-related brain potential. We found differences in processes of change detection depending on whether the Standard was language-familiar, or not. Whereas, the lexicality of the Deviant had no effect on the processes of change detection. Also, language-familiar Standards processed differently than language-unfamiliar ones. We suggest that pre-attentive (default) tuning to meaningful words sets up language-specific preparatory processes that affect change detection in speech sequences.

Adolescent↗
PubMed2004

Input to verbal working memory: Preattentive construction of the central speech representation.

Working memory uses central sound representations as an informational basis. The central sound representation is the temporally and feature-integrated mental representation that corresponds to phenomenal perception. It is used in (higher-order) mental operations and stored in long-term memory. In the bottom-up processing path, the central sound representation can be probed at the level of auditory sensory memory with the mismatch negativity (MMN) of the event-related potential. The present paper reviews a newly developed MMN paradigm to tap into the processing of speech sound representations. Preattentive vowel categorization based on F1-F2 formant information occurs in speech sounds and complex tones even under conditions of high variability of the auditory input. However, an additional experiment demonstrated the limits of the preattentive categorization of language-relevant information. It tested whether the system categorizes complex tones containing the F1 and F2 formant components of the vowel /a/ differently than six sounds with nonlanguage-like F1-F2 combinations. From the absence of an MMN in this experiment, it is concluded that no adequate vowel representation was constructed. This shows limitations of the capability of preattentive vowel categorization.

Adult↗
PubMed2004

Pre-attentive perception of vowel phonemes from variable speech stimuli.

Understanding speech requires the construction of phonetic representations while abstracting from specific sound features. To understand different speakers of varying pitches of voice, loudness, or timbre, categorical phoneme information needs to be rapidly extracted from dynamic, changing speech input. The present study demonstrated a genuine MMN to tokens of /a/ and /i/ vowels varying in pitch of voice and amplitude envelope when they occurred infrequently among the respective other vowels. These data indicate that the speech perception system pre-attentively extracted the F1/F2 formant information despite the language-irrelevant variation in the sound input.

Acoustic Stimulation↗
PubMed2004

Individual and group modelling of aesthetic judgment strategies.

Individual differences in aesthetic judgments were investigated by comparing quantitative group and individual performance models of the judgment processes. Aesthetic judgments of beauty over novel, formal, graphic patterns were collected from 34 non-artist college students using a two-step ranking-rating procedure. Their judgment processes were individually modelled using Judgment Analysis. The participants showed noted individual differences. Certain features of the stimulus material, which were considered to contribute to the picture's beauty by one participant, were used in an opposing fashion by another. A group model was derived based on the average ratings of the patterns' beauty. It was concluded that the group model was not an adequate representation of the present data, whereas the data revealed systematic judgment processes at the individual subject level.

Adult↗
PubMed2004

The primacy of beauty in judging the aesthetics of objects.

The conceptual structure of the aesthetics of objects was investigated. To this end, associative namings for the word "aesthetics" were collected from 311 nonartist German college students in a timed verbal association task. 590 different adjectives were produced, depicting diversification of the concept. The adjective "beautiful" was given by more than 90% of the participants. The adjective "ugly" was the second most frequent naming, used by almost half of the students. All other namings were markedly less frequently produced. It is argues that the beautiful-ugly dimension represents the primary concept in the aesthetics of objects, so that performing aesthetic judgments of the beauty of objects comes naturally to individuals. In other words, the most prototypical aesthetic judgments are those of beauty. Furthermore, the majority of generated words had a positive valence as measured by an additional valence-rating study including 41 participants. This result contrasts with comparable studies of emotion terms, as such studies typically show a negativity bias. Frequency in general language use and valence of the adjectives did not account for the results.

Adolescent↗
PubMed2004

Resin composites in minimally invasive dentistry.

The concept of minimally invasive dentistry will provide favorable conditions for the use of composite resin. However, a number of factors must be considered when placing composite resins in conservatively prepared cavities, including: aspects on the adaptation of the composite resin to the cavity walls; the use of adhesives; and techniques for obtaining adequate proximal contacts. The clinician must also adopt an equally conservative approach when treating failed restorations. The quality of the composite resin restoration will not only be affected by the outline form of the preparation but also by the clinician's technique and understanding of the materials.

Composite Resins↗
PubMed2003

Mismatch negativity to pitch change: varied stimulus proportions in controlling effects of neural refractoriness on human auditory event-related brain potentials.

Based on a memory-comparison process, changes in the pitch of repetitive sounds are pre-attentively detected, reflected by the mismatch negativity (MMN) event-related brain potential (ERP). In such oddball sequences, ERP responses are also affected by differential refractory states of frequency-specific afferent cortical neurons. This contamination of MMN can be controlled using an additional blocked sequence of equiprobable tones. The present study investigated effects of varying the in-sequence probabilities of these control tones from 10 to 45%, respectively. Results showed that an equal distribution of all control-sequence tones is not necessary for efficiently removing neural refractoriness effects on the ERPs. The genuine memory-comparison-based frequency-change MMN can be estimated using sequences, within which the number of equiprobable control tones varies between three and nine.

Adult↗
PubMed2003

Measuring duration mismatch negativity.

OBJECTIVE: Automatic comparisons of sound duration in auditory sensory memory are typically investigated by comparing event-related potentials (ERPs) to standard and deviant stimuli presented in oddball blocks. Deviants elicit mismatch negativity (MMN). This procedure might overestimate an MMN contribution reflecting automatic sensory memory processes because of differential states of refractoriness of respectively recruited neural populations [Neuroreport 1996;7:3005; Psychophysiology 2001;38:723]. Here, memory-comparison-based Duration MMN contributions were investigated using various experimental protocols. METHODS: Memory-comparison-based first-order Duration MMN was investigated using 4 blocked conditions: (a) descending Deviant (100 ms, P=0.14), 150 ms Standard; (b) reverse ascending Deviant (150 ms), 100 ms Standard; (c) Control comprised of 7 equiprobable durations between 25 and 175 ms; and additionally (d) equiprobable tones between 100 and 400 ms. Using the former 3 conditions, Deviants, Standards and Controls were physically identical. RESULTS: Comparing Deviants and Controls excluded potential refractoriness effects, and a decomposition of memory-comparison-based MMN and residual MMN was demonstrated. Genuine Duration MMN was also obtained in the deviant-standard-reverse comparison. CONCLUSIONS: Using a blocked control condition yielded equivalent results to reversing the role of deviant and standard in two separate oddball blocks. Using the reverse ascending deviant condition is thus sufficient as a control.

Acoustic Stimulation↗
PubMed2003

Effect of composition and complexity of dentin-bonding agents on operator variability--analysis of gap formation using confocal microscopy.

The variability of gap formation due to different operators and bonding agents around dentin-bonded composites in cylindrical cavities (internal diameter, 3 mm; depth, 1 mm; n = 210) was evaluated in vitro. Seven dentists evaluated two experimental bonding systems (A & B) and one commercial product (C) by each treating 10 teeth with each system. One of the investigators restored all cavities with composite (Z100, 3M ESPE) and removed excess material to expose the cavity margins. After storage in water for 1 wk, the maximum gap-width was measured using a confocal microscope and statistically analysed. The relative gap-widths (%) for the three bonding systems were not statistically different. Means +/- SD were 0.18 +/- 0.06, 0.19 +/- 0.08, and 0.20 +/- 0.06 for groups A, B, and C, respectively. The variation caused by the operator-material interaction was significant. When the operator's variability (SD) within the different materials was examined, group C displayed a significantly lower variability than the other two. It was concluded that the operator variable is a more important consideration than the material variable. The self-etching system performed better than the more complex A and B systems when variability rather than gap size was considered.

Acid Etching, Dental↗
PubMed2003

Electrical brain responses to descriptive versus evaluative judgments of music.

The present study was aimed at finding neural correlates of aesthetic versus descriptive listening of the same musical cadences. Results showed that aesthetic listening generated greater right frontocentral negativities than did descriptive listening, indicating distinct cortical mechanisms for aesthetic versus descriptive processing of music.

Auditory Cortex↗