Auditory Sensory Systems Research Articles

The auditory cortex hosts network nodes influential for emotion processing: An fMRI study on music-evoked fear and joy

Sound is a potent elicitor of emotions. Auditory core, belt and parabelt regions have anatomical connections to a large array of limbic and paralimbic structures which are involved in the generation of affective activity. However, little is known about the functional role of auditory cortical regions in emotion processing. Using functional magnetic resonance imaging and music stimuli that evoke joy or fear, our study reveals that anterior and posterior regions of auditory association cortex have emotion-characteristic functional connectivity with limbic/paralimbic (insula, cingulate cortex, and striatum), somatosensory, visual, motor-related, and attentional structures. We found that these regions have remarkably high emotion-characteristic eigenvector centrality, revealing that they have influential positions within emotion-processing brain networks with “small-world” properties. By contrast, primary auditory fields showed surprisingly strong emotion-characteristic functional connectivity with intra-auditory regions. Our findings demonstrate that the auditory cortex hosts regions that are influential within networks underlying the affective processing of auditory information. We anticipate our results to incite research specifying the role of the auditory cortex—and sensory systems in general—in emotion processing, beyond the traditional view that sensory cortices have merely perceptual functions.

ВПЛИВ НА ПРИЙНЯТТЯ РІШЕНЬ СПОЖИВАЧІВ НА РИНКУ ТУРИСТИЧНИХ ПОСЛУГ ЗА ДОПОМОГОЮ ТЕХНОЛОГІЙ НЕЙРОМАРКЕТИНГУ

The constant renewal and growth of the number of tourism destinations and types of tourist services, changing consumer preferences, increasing competition in the market force us to turn to innovative marketing technologies, as traditional ones lose their effectiveness. Given the fact that tourists often choose a travel package with a unique set of services, as an important aspect of travel for people are emotions, impressions, and unique feelings, the study chose psychological methods, techniques, technologies, and tools of neuromarketing (neural marketing) to involve consumers in the market of tourist services by influencing their behavior. In particular, the article focuses on theoretical and applied aspects of the use of neuromarketing technologies to influence consumer decision-making in the travel services market through the impact on visual, auditory, olfactory, gustatory, and tactile sensory systems. It was found that marketers, in particular in the field of tourism, most often use visual and auditory methods of influence, but now is becoming increasingly popular aroma marketing and marketing of taste, which affects the sense of smell and taste buds. All these methods affect the associative memory of a person and this further helps to create a permanent customer base and attract new consumers. Attention is paid to highlighting the specifics of the influence of color or a certain combination of colors on the human subconscious. A set of tools and technologies of neuromarketing are used in tourism to attract attention, change the mood of the tourist, and evoke the right emotions, including such as illustrations, music, flavor, taste, the atmosphere of restaurants, tastings, and others. Based on the study of the peculiarities of the use of neuromarketing (sensory marketing) technologies in tourism, the authors identified several benefits that help attract new customers and encourage them to make purchases.

The effect of passive rotation in horizontal plane on perception of moving sound images

During the standard step examination in the rotary chair Nydiag 200 the authors, alongside with the rotary nystagmus, registered the evaluation of acoustic images motion direction. During the initial 20 seconds of the patient rotation, the patient, reliably more frequently than at rest, evaluated the acoustic images moving to the right as those moving to the left. The changes of localization were made in the direction opposite to that of rotation. No reliable changes have been found during the reverse movement. During the initial 20 seconds after patient rotation to the left the direction of the change of localization coincided with the movement direction. The revealed asymmetry of localization of the moving acoustic images during the rotation in a horizontal plane supports observations of Lewald and Karnath (2001) about asymmetrical effect of rotation to the right and to the left on localization of immobile acoustic images and brings up a question about the role of otolith asymmetry in the interactions of vestibular and auditory sensory systems.

Habituation deficit of auditory N100m in patients with fibromyalgia.

Habituation refers to the brain's inhibitory mechanism against sensory overload and its brain correlate has been investigated in the form of a well-defined event-related potential, N100 (N1). Fibromyalgia is an extensively described chronic pain syndrome with concurrent manifestations of reduced tolerance and enhanced sensation of painful and non-painful stimulation, suggesting an association with central amplification of all sensory domains. Among diverse sensory modalities, we utilized repetitive auditory stimulation to explore the anomalous sensory information processing in fibromyalgia as evidenced by N1 habituation. Auditory N1 was assessed in 19 fibromyalgia patients and age-, education- and gender-matched 21 healthy control subjects under the duration-deviant passive oddball paradigm and magnetoencephalography recording. The brain signal of the first standard stimulus (following each deviant) and last standard stimulus (preceding each deviant) were analysed to identify N1 responses. N1 amplitude difference and adjusted amplitude ratio were computed as habituation indices. Fibromyalgia patients showed lower N1 amplitude difference (left hemisphere: p=0.004; right hemisphere: p=0.034) and adjusted N1 amplitude ratio (left hemisphere: p=0.001; right hemisphere: p=0.052) than healthy control subjects, indicating deficient auditory habituation. Further, augmented N1 amplitude pattern (p=0.029) during the stimulus repetition was observed in fibromyalgia patients. Fibromyalgia patients failed to demonstrate auditory N1 habituation to repetitively presenting stimuli, which indicates their compromised early auditory information processing. Our findings provide neurophysiological evidence of inhibitory failure and cortical augmentation in fibromyalgia. WHAT'S ALREADY KNOWN ABOUT THIS TOPIC?: Fibromyalgia has been associated with altered filtering of irrelevant somatosensory input. However, whether this abnormality can extend to the auditory sensory system remains controversial. N!00, an event-related potential, has been widely utilized to assess the brain's habituation capacity against sensory overload. WHAT DOES THIS STUDY ADD?: Fibromyalgia patients showed defect in N100 habituation to repetitive auditory stimuli, indicating compromised early auditory functioning. This study identified deficient inhibitory control over irrelevant auditory stimuli in fibromyalgia.

Sensory Modulation Treatment on a Psychiatric Inpatient Unit: Results of a Pilot Program.

The purpose of the current pilot program was to measure efficacy of sensory modulation treatment for adults (N = 20) admitted to an inpatient, involuntary psychiatric unit. Efficacy of 1-hour group (n = 10) and 1-hour individual (n = 9) sensory modulation treatment was measured via pre- and postintervention self-rating scales (visual analog scale from 0 to 10, with 0 = low arousal and 10 = high arousal) and post-survey. Results indicated treatment elicited an average self-perceived change in arousal of 1.93. Group treatment elicited an average self-rating change of 1.79, whereas individual treatment elicited an average change of 2.67. For participants who initially rated their arousal level ≥6, group treatment elicited a change of 4.5, whereas individual treatment elicited a change of 7.5. Participants sought materials and activities that were primarily categorized into the olfactory, gustatory, and auditory sensory systems.

Driving the Early Auditory Network the Old-Fashioned Way

Spontaneous neuronal activity during the development of the auditory sensory system is important in establishing mature connectivity. Wang et al. show that glia-like cells drive spontaneous spiking in neighboring cochlear inner hair cells via a process that involves osmotic cell shrinkage and the secretion of potassium ions.

Evidence of multisensory plasticity: Asymmetrical medial geniculate body in people with one eye.

The medial geniculate body (MGB) plays a central role in auditory processing with both efferent and afferent tracts to primary auditory cortex. People who have lost one eye early in life have enhanced sound localization, lack visual over auditory dominance and integrate auditory and visual information optimally, similar to controls, despite taking longer to localize unimodal visual stimuli. Compared to controls, people with one eye have decreased lateral geniculate nuclei (LGN) volume as expected given the 50% deafferentation of the visual system. However, LGN volume is larger than predicted contralateral to the remaining eye, indicating altered structural development likely through recruitment of deafferented LGN cells.Purpose: the current study investigated whether structural MGB changes are also present in this group given the changes they exhibit in auditory processing.Methods: MGB volumes were measured in adults who had undergone early unilateral eye enucleation and were compared to binocularly intact controls.Results: unlike controls, people with one eye had a significant asymmetry with a larger left compared to right MGB, independent of eye of enucleation. MGB volume correlated positively with LGN volume in people with one eye.Conclusions: volume asymmetry in the MGB in people with one eye may represent increased interactions between the left MGB and primary auditory cortex. This interaction could contribute to increased auditory and other left hemisphere-dominant processing, including language, as compensation for the loss of one half of visual inputs early in life. The positive correlation between MGB and LGN volume is not due to space constraints but rather indicates increased plasticity in both auditory and visual sensory systems following early eye enucleation.

An investigation of matching symmetry in the human pinnae with possible implications for 3D ear recognition and sound localization.

The human external ears, or pinnae, have an intriguing shape and, like most parts of the human external body, bilateral symmetry is observed between left and right. It is a well-known part of our auditory sensory system and mediates the spatial localization of incoming sounds in 3D from monaural cues due to its shape-specific filtering as well as binaural cues due to the paired bilateral locations of the left and right ears. Another less broadly appreciated aspect of the human pinna shape is its uniqueness from one individual to another, which is on the level of what is seen in fingerprints and facial features. This makes pinnae very useful in human identification, which is of great interest in biometrics and forensics. Anatomically, the type of symmetry observed is known as matching symmetry, with structures present as separate mirror copies on both sides of the body, and in this work we report the first such investigation of the human pinna in 3D. Within the framework of geometric morphometrics, we started by partitioning ear shape, represented in a spatially dense way, into patterns of symmetry and asymmetry, following a two-factor anova design. Matching symmetry was measured in all substructures of the pinna anatomy. However, substructures that 'stick out' such as the helix, tragus, and lobule also contained a fair degree of asymmetry. In contrast, substructures such as the conchae, antitragus, and antihelix expressed relatively stronger degrees of symmetric variation in relation to their levels of asymmetry. Insights gained from this study were injected into an accompanying identification setup exploiting matching symmetry where improved performance is demonstrated. Finally, possible implications of the results in the context of ear recognition as well as sound localization are discussed.

A Revıew Artıcle: Cerebellum And Eyesıght

The cerebellum plays a significant role in the maintenance of equilibrium and the coordination of head and eye movements. The cerebellum receives extensive information from visual, somesthetic, vestibular and auditory sensory systems, as well as from motor and nonmotor areas of the cerebral cortex. The cerebellum was more active during independent rather than coordinated eye and hand tracking. Performance when tracking with the hand alone was worse than in the coordinated eye and hand condition. Cerebellum was significantly activated in coordinated eye–hand tracking compared to isolated eye and hand movements. Patients with cerebellar disease, eye movements, limb movements, gait and speech all may be affected. Bulbar muscles may also be affected, numerous disturbances of oculomotor activity, including nystagmus. In cerebellar disease decreased tone in postural muscles, Hypotonia in occulomotor muscles results in difficulty in maintaining the gaze. Studies investigating the relationship between the cerebellum and eyesight were revised in this manuscript.

Exploiting Multimedia in Reproductive Science Education: Research Findings

Education in reproductive science is operating from an outdated paradigm of teaching and learning. Traditionally, reproductive education follows the pattern where students read a textbook, listen to instructor presentations, re-read the textbook and class notes and then complete a test. This paradigm is inefficient, costly and has not incorporated the potential that technology can offer with respect to increases in student learning. Further, teachers of reproductive science (and all of science for that matter) have little training in the use of documented methods of instructional design and cognitive psychology. Thus, most of us have learned to teach by repeating the approaches our mentors used (both good and bad). The technology now exists to explain complex topics using multimedia presentations in which digital animation and three-dimensional anatomical reconstructions greatly reduce time required for delivery while at the same time improving student understanding. With funding from the Small Business Innovation Research program through the U.S. Department of Education, we have developed and tested a multimedia approach to teaching complex concepts in reproductive physiology. The results of five separate experiments involving 1058 university students and 122 patients in an OB/GYN clinic indicate that students and patients learned as much or more in less time when viewing the multimedia presentations when compared to traditional teaching methodologies.

Chemical Basis of Prey Recognition in Thamnophiine Snakes: The Unexpected New Roles of Parvalbumins

Detecting and locating prey are key to predatory success within trophic chains. Predators use various signals through specialized visual, olfactory, auditory or tactile sensory systems to pinpoint their prey. Snakes chemically sense their prey through a highly developed auxiliary olfactory sense organ, the vomeronasal organ (VNO). In natricine snakes that are able to feed on land and water, the VNO plays a critical role in predatory behavior by detecting cues, known as vomodors, which are produced by their potential prey. However, the chemical nature of these cues remains unclear. Recently, we demonstrated that specific proteins–parvalbumins–present in the cutaneous mucus of the common frog (Rana temporaria) may be natural chemoattractive proteins for these snakes. Here, we show that parvalbumins and parvalbumin-like proteins, which are mainly intracellular, are physiologically present in the epidermal mucous cells and mucus of several frog and fish genera from both fresh and salt water. These proteins are located in many tissues and function as Ca2+ buffers. In addition, we clarified the intrinsic role of parvalbumins present in the cutaneous mucus of amphibians and fishes. We demonstrate that these Ca2+-binding proteins participate in innate bacterial defense mechanisms by means of calcium chelation. We show that these parvalbumins are chemoattractive for three different thamnophiine snakes, suggesting that these chemicals play a key role in their prey-recognition mechanism. Therefore, we suggest that recognition of parvalbumin-like proteins or other calcium-binding proteins by the VNO could be a generalized prey-recognition process in snakes. Detecting innate prey defense mechanism compounds may have driven the evolution of this predator-prey interaction.

Gustation.

Much has been discovered over the last few decades about the anatomy and physiology of the human taste system, most notably its receptor mechanisms and intermodal factors that influence its function. While the taste system works in concert with the olfactory, somatosensory, auditory, and visual sensory systems to establish the overall gestalt of flavor, its primary specialization is to ensure that the organism obtains energy, maintains proper electrolyte balance, and avoids ingestion of toxic substances. Despite its focus on inborn functions, taste-like its sister sense of smell-is remarkably malleable, reflecting the need to adapt to changing circumstances and general nutrient availability. It is now widely appreciated that taste dysfunction is common in many diseases and disorders, and is a frequent side effect of a number of medications. This interdisciplinary review examines salient aspects of the human gustatory system, including its anatomy, physiology, and pathophysiology. WIREs Cogn Sci 2012, 3:29-46. doi: 10.1002/wcs.156 For further resources related to this article, please visit the WIREs website.

Audiotactile interactions in temporal perception

In the present review, we focus on how commonalities in the ontogenetic development of the auditory and tactile sensory systems may inform the interplay between these signals in the temporal domain. In particular, we describe the results of behavioral studies that have investigated temporal resolution (in temporal order, synchrony/asynchrony, and simultaneity judgment tasks), as well as temporal numerosity perception, and similarities in the perception of frequency across touch and hearing. The evidence reviewed here highlights features of audiotactile temporal perception that are distinctive from those seen for other pairings of sensory modalities. For instance, audiotactile interactions are characterized in certain tasks (e.g., temporal numerosity judgments) by a more balanced reciprocal influence than are other modality pairings. Moreover, relative spatial position plays a different role in the temporal order and temporal recalibration processes for audiotactile stimulus pairings than for other modality pairings. The effect exerted by both the spatial arrangement of stimuli and attention on temporal order judgments is described. Moreover, a number of audiotactile interactions occurring during sensory-motor synchronization are highlighted. We also look at the audiotactile perception of rhythm and how it may be affected by musical training. The differences emerging from this body of research highlight the need for more extensive investigation into audiotactile temporal interactions. We conclude with a brief overview of some of the key issues deserving of further research in this area.

Human Visual System Automatically Encodes Sequential Regularities of Discrete Events

For our adaptive behavior in a dynamically changing environment, an essential task of the brain is to automatically encode sequential regularities inherent in the environment into a memory representation. Recent studies in neuroscience have suggested that sequential regularities embedded in discrete sensory events are automatically encoded into a memory representation at the level of the sensory system. This notion is largely supported by evidence from investigations using auditory mismatch negativity (auditory MMN), an event-related brain potential (ERP) correlate of an automatic memory-mismatch process in the auditory sensory system. However, it is still largely unclear whether or not this notion can be generalized to other sensory modalities. The purpose of the present study was to investigate the contribution of the visual sensory system to the automatic encoding of sequential regularities using visual mismatch negativity (visual MMN), an ERP correlate of an automatic memory-mismatch process in the visual sensory system. To this end, we conducted a sequential analysis of visual MMN in an oddball sequence consisting of infrequent deviant and frequent standard stimuli, and tested whether the underlying memory representation of visual MMN generation contains only a sensory memory trace of standard stimuli (trace-mismatch hypothesis) or whether it also contains sequential regularities extracted from the repetitive standard sequence (regularity-violation hypothesis). The results showed that visual MMN was elicited by first deviant (deviant stimuli following at least one standard stimulus), second deviant (deviant stimuli immediately following first deviant), and first standard (standard stimuli immediately following first deviant), but not by second standard (standard stimuli immediately following first standard). These results are consistent with the regularity-violation hypothesis, suggesting that the visual sensory system automatically encodes sequential regularities. In combination with a wide range of auditory MMN studies, the present study highlights the critical role of sensory systems in automatically encoding sequential regularities when modeling the world.

Sounds, Behaviour, and Auditory Receptors of the Armoured Ground Cricket,Acanthoplus longipes

The auditory sensory system of the taxon Hetrodinae has not been studied previously. Males of the African armoured ground cricket, Acanthoplus longipes (Orthoptera: Tettigoniidae: Hetrodinae) produce a calling song that lasts for minutes and consists of verses with two pulses. About three impulses are in the first pulse and about five impulses are in the second pulse. In contrast, the disturbance stridulation consists of verses with about 14 impulses that are not separated in pulses. Furthermore, the inter-impulse intervals of both types of sounds are different, whereas verses have similar durations. This indicates that the neuronal networks for sound generation are not identical. The frequency spectrum peaks at about 15 kHz in both types of sounds, whereas the hearing threshold has the greatest sensitivity between 4 and 10 kHz. The auditory afferents project into the prothoracic ganglion. The foreleg contains about 27 sensory neurons in the crista acustica; the midleg has 18 sensory neurons, and the hindleg has 14. The auditory system is similar to those of other Tettigoniidae.

Prestimulus Oscillatory Brain Activity Influences The Perception Of The McGurk-Effect

Event Abstract Back to Event Prestimulus Oscillatory Brain Activity Influences The Perception Of The McGurk-Effect Julian Keil1*, Niklas Ihssen2 and Nathan Weisz1 1 University of Konstanz, Germany 2 University of Bangor, United Kingdom The McGurk-effect is a perceptual illusion, which demonstrates an interaction between auditory and visual sensory systems in speech perception. If a mismatch between the perception of a sound and the accompanying visual input occurs, it has been observed that the unified perception of both modalities fuses to a novel percept that neither matches the sound nor the sight. This effect does not appear in all mismatched trials, but only in 60-80%. The present study was designed to clarify the conditions under which this effect occurs and to identify cerebral sources associated with it. We are interested in the potential influence of ongoing brain oscillations associated to and prior to varying perception. In the present study, videos of an actor articulating syllables (e.g. aba) were dubbed with the audio tracks of different syllables (e.g. aga). The subjects were presented with a sequence of 390 videos, part of which contained the original audio tracks, part of which contained mismatching tracks. As an indicator of the perception, the subjects had to report via button press what syllable they had perceived. MEG was used to record event related and oscillatory activity during the stimulation. Cortical sources associated with different perceptions were identified and phase-locking between these areas was analyzed. Previous studies have shown an increase in gamma band activity related to incongruent stimuli. FMRI-studies have shown an involvement of superior temporal gyrus in speech perception. Preliminary results indicate, that the perception of the McGurk-Effect is associated with both, a higher pre-stimulus gamma activity in parietal and frontal cortical areas and a higher post-stimulus gamma activity in parietal cortical areas. Differences in phase-locking of cortical sources between different perceptions were observed. We conclude, that certain ongoing brain oscillations facilitate the perception the McGurk-Effect and also influence the perception of natural stimuli. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: Sensory Processing and Functional Connectivity Citation: Keil J, Ihssen N and Weisz N (2010). Prestimulus Oscillatory Brain Activity Influences The Perception Of The McGurk-Effect. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00171 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Mar 2010; Published Online: 26 Mar 2010. * Correspondence: Julian Keil, University of Konstanz, Konstanz, Germany, julian.keil@uni-konstanz.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Julian Keil Niklas Ihssen Nathan Weisz Google Julian Keil Niklas Ihssen Nathan Weisz Google Scholar Julian Keil Niklas Ihssen Nathan Weisz PubMed Julian Keil Niklas Ihssen Nathan Weisz Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Reduction of the postexcitatory cortical inhibition upon paired-click auditory stimulation in patients with Parkinson’s disease

The aims of this study were: to investigate the postexcitatory inhibition of cortical evoked potentials on auditory paired-click stimulation in patients with Parkinson's disease (PD), to analyze the correlation of N1-P2 amplitude ratios (A2/A1) with latency of the P300 auditory event-related potential and to determine the influence of Levodopa intake on postexcitatory inhibition and P300 latency. The central (Cz) auditory evoked potentials were recorded in 61 patients with PD and 21 age-matched healthy subjects. Postexcitatory inhibition in auditory cortex in PD was significantly reduced for interstimulus intervals 500, 700 and 900ms compared to control group. The degree of this reduction correlated positively with the potential P300 latency and negatively with the summary score of the Mini Mental State Examination (MMSE) which was used to study general cognitive status of the PD patients. Increase of the postexcitatory inhibition towards normal values and decrease of the P300 latency were observed (P<0.001) following the administration of Levodopa. The findings of this study testify that inhibitory processes in auditory cortex are deficient in PD patients. The positive effect of Levodopa administration indicates an important role of dopamine-dependent neural mechanisms in modulation of inhibitory processes in the auditory sensory system. The results show that inability of the brain to provide normal inhibition in PD is accompanied by the decline of cognitive indices, including parameters of evoked potential P300 that is related to fundamental aspects of cognitive functions, such as attention and memory.

ERP Evaluation of Auditory Sensory Memory Systems in Adults with Intellectual Disability

Auditory sensory memory stage can be functionally divided into two subsystems; transient-detector system and permanent feature-detector system (). We assessed these systems in persons with intellectual disability by measuring event-related potentials (ERPs) N1 and mismatch negativity (MMN), which reflect the two auditory subsystems, respectively. Added to these, P3a (an ERP reflecting stage after sensory memory) was evaluated. Either synthesized vowels or simple tones were delivered during a passive oddball paradigm to adults with and without intellectual disability. ERPs were recorded from midline scalp sites (Fz, Cz, and Pz). Relative to control group, participants with the disability exhibited greater N1 latency and less MMN amplitude. The results for N1 amplitude and MMN latency were basically comparable between both groups. IQ scores in participants with the disability revealed no significant relation with N1 and MMN measures, whereas the IQ scores tended to increase significantly as P3a latency reduced. These outcomes suggest that persons with intellectual disability might own discrete malfunctions for the two detector systems in auditory sensory-memory stage. Moreover, the processes following sensory memory might be partly related to a determinant of mental development.

Spatiotemporal dynamics of single-letter reading: a combined ERP-FMRI study.

This work investigates the neural correlates of single-letter reading by combining event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), thus exploiting their complementary spatiotemporal resolutions. Three externally-paced reading tasks were administered with an event-related design: passive observation of letters and symbols and active reading aloud of letters. ERP and fMRI data were separately recorded from 8 healthy adults during the same experimental conditions. Due to the presence of artifacts in the EEG signals, two subjects were discarded from further analysis. Independent Component Analysis was applied to ERPs, after dimensionality reduction by Principal Component Analysis: some independent components were clearly related to specific reading functions and the associated current density distributions in the brain were estimated with Low Resolution Electromagnetic Tomography Analysis method (LORETA). The impulse hemodynamic response function was modeled as a linear combination of linear B-spline functions and fMRI statistical analysis was performed by multiple linear regression. fMRI and LORETA maps were superimposed in order to identify the overlapping activations and the activated regions specifically revealed by each modality. The results showed the existence of neuronal networks functionally specific for letter processing and for explicit verbal-motor articulation, including the temporo-parietal and frontal regions. Overlap between fMRI and LORETA results was observed in the inferior temporal-middle occipital gyrus, suggesting that this area has a crucial and multifunctional role for linguistic and reading processes, likely because its spatial location and strong interconnection with the main visual and auditory sensory systems may have favored its specialization in grapheme-phoneme matching.

Domain-dependent activation during spatial and nonspatial auditory working memory

Visual system has been proposed to be divided into two, the ventral and dorsal, processing streams. The ventral pathway is thought to be involved in object identification whereas the dorsal pathway processes information regarding the spatial locations of objects and the spatial relationships among objects. Several studies on working memory (WM) processing have further suggested that there is a dissociable domain-dependent functional organization within the prefrontal cortex for processing of spatial and nonspatial visual information. Also the auditory system is proposed to be organized into two domain-specific processing streams, similar to that seen in the visual system. Recent studies on auditory WM have further suggested that maintenance of nonspatial and spatial auditory information activates a distributed neural network including temporal, parietal, and frontal regions but the magnitude of activation within these activated areas shows a different functional topography depending on the type of information being maintained. The dorsal prefrontal cortex, specifically an area of the superior frontal sulcus (SFS), has been shown to exhibit greater activity for spatial than for nonspatial auditory tasks. Conversely, ventral frontal regions have been shown to be more recruited by nonspatial than by spatial auditory tasks. It has also been shown that the magnitude of this dissociation is dependent on the cognitive operations required during WM processing. Moreover, there is evidence that within the nonspatial domain in the ventral prefrontal cortex, there is an across-modality dissociation during maintenance of visual and auditory information. Taken together, human neuroimaging results on both visual and auditory sensory systems support the idea that the prefrontal cortex is organized according to the type of information being maintained in WM.