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Magnetic Resonance in Medical Sciences... Jul 2024Diffusion-weighted MRI (dMRI) provides a unique non-invasive view of human brain tissue properties. The present review article focuses on tractometry analysis methods... (Review)
Review
Diffusion-weighted MRI (dMRI) provides a unique non-invasive view of human brain tissue properties. The present review article focuses on tractometry analysis methods that use dMRI to assess the properties of brain tissue within the long-range connections comprising brain networks. We focus specifically on the major white matter tracts that convey visual information. These connections are particularly important because vision provides rich information from the environment that supports a large range of daily life activities. Many of the diseases of the visual system are associated with advanced aging, and tractometry of the visual system is particularly important in the modern aging society. We provide an overview of the tractometry analysis pipeline, which includes a primer on dMRI data acquisition, voxelwise model fitting, tractography, recognition of white matter tracts, and calculation of tract tissue property profiles. We then review dMRI-based methods for analyzing visual white matter tracts: the optic nerve, optic tract, optic radiation, forceps major, and vertical occipital fasciculus. For each tract, we review background anatomical knowledge together with recent findings in tractometry studies on these tracts and their properties in relation to visual function and disease. Overall, we find that measurements of the brain's visual white matter are sensitive to a range of disorders and correlate with perceptual abilities. We highlight new and promising analysis methods, as well as some of the current barriers to progress toward integration of these methods into clinical practice. These barriers, such as variability in measurements between protocols and instruments, are targets for future development.
Topics: Humans; White Matter; Visual Pathways; Diffusion Tensor Imaging; Brain; Diffusion Magnetic Resonance Imaging; Image Processing, Computer-Assisted; Vision Disorders
PubMed: 38866532
DOI: 10.2463/mrms.rev.2024-0007 -
Perception Jun 2024Researchers have been focusing on perceptual characteristics of autism spectrum disorder (ASD) in terms of sensory hyperreactivity. Previously, we demonstrated that...
Researchers have been focusing on perceptual characteristics of autism spectrum disorder (ASD) in terms of sensory hyperreactivity. Previously, we demonstrated that temporal resolution, which is the accuracy to differentiate the order of two successive vibrotactile stimuli, is associated with the severity of sensory hyperreactivity. We currently examined whether an increase in the perceptual intensity of a tactile stimulus, despite its short duration, is derived from high temporal resolution and high frequency of sensory temporal summation. Twenty ASD and 22 typically developing (TD) participants conducted two psychophysical experimental tasks to evaluate of vibrotactile stimulus with same amplitude and to evaluate temporal resolution. The sensory hyperreactivity was estimated using self-reported questionnaire. There was no relationship between the temporal resolution and the duration of detectable stimuli in both groups. However, the ASD group showed severe sensory hyperreactivity in daily life than TD group, and the ASD participants with severe sensory hyperreactivity tended to have high temporal resolution, not high sensitivity of detectable duration. Contrary to the hypothesis, there might be different processing between temporal resolution and sensitivity for stimulus detection. We suggested that the atypical temporal processing would affect to sensory reactivity in ASD.
PubMed: 38863412
DOI: 10.1177/03010066241259729 -
PLoS Biology Jun 2024Despite the diverse genetic origins of autism spectrum disorders (ASDs), affected individuals share strikingly similar and correlated behavioural traits that include...
Shared behavioural impairments in visual perception and place avoidance across different autism models are driven by periaqueductal grey hypoexcitability in Setd5 haploinsufficient mice.
Despite the diverse genetic origins of autism spectrum disorders (ASDs), affected individuals share strikingly similar and correlated behavioural traits that include perceptual and sensory processing challenges. Notably, the severity of these sensory symptoms is often predictive of the expression of other autistic traits. However, the origin of these perceptual deficits remains largely elusive. Here, we show a recurrent impairment in visual threat perception that is similarly impaired in 3 independent mouse models of ASD with different molecular aetiologies. Interestingly, this deficit is associated with reduced avoidance of threatening environments-a nonperceptual trait. Focusing on a common cause of ASDs, the Setd5 gene mutation, we define the molecular mechanism. We show that the perceptual impairment is caused by a potassium channel (Kv1)-mediated hypoexcitability in a subcortical node essential for the initiation of escape responses, the dorsal periaqueductal grey (dPAG). Targeted pharmacological Kv1 blockade rescued both perceptual and place avoidance deficits, causally linking seemingly unrelated trait deficits to the dPAG. Furthermore, we show that different molecular mechanisms converge on similar behavioural phenotypes by demonstrating that the autism models Cul3 and Ptchd1, despite having similar behavioural phenotypes, differ in their functional and molecular alteration. Our findings reveal a link between rapid perception controlled by subcortical pathways and appropriate learned interactions with the environment and define a nondevelopmental source of such deficits in ASD.
Topics: Animals; Disease Models, Animal; Mice; Visual Perception; Haploinsufficiency; Avoidance Learning; Autism Spectrum Disorder; Male; Behavior, Animal; Mice, Inbred C57BL; Histone-Lysine N-Methyltransferase; Autistic Disorder
PubMed: 38857283
DOI: 10.1371/journal.pbio.3002668 -
BioRxiv : the Preprint Server For... May 2024Albinism is an inherited disorder characterized by disrupted melanin production in the eye, and often in the skin and hair. This retinal hypopigmentation is accompanied...
Albinism is an inherited disorder characterized by disrupted melanin production in the eye, and often in the skin and hair. This retinal hypopigmentation is accompanied by pathological decussation of many temporal retinal afferents at the optic chiasm during development, ultimately resulting in partially superimposed representations of opposite visual hemifields in each cortical hemisphere. Within these aberrant regions of hemifield overlap, individual voxels have been shown to have bilateral, dual population receptive fields (pRFs) responding to roughly mirror-image locations across the vertical meridian. Nonetheless, how these two conflicting inputs combine to determine a voxel's response to image contrast is still unknown. To address this, we stimulated the right and left hemifields with separately controlled sinusoidal gratings, each having a variety of contrasts (0, 8, 20, 45, 100%), and extracted voxel-wise BOLD response amplitudes to each contrast combination in visual areas V1-V3. We then compared voxels' responses to each hemifield stimulated individually with conditions when both hemifields were stimulated simultaneously. We hypothesized that simultaneous stimulation of the two pRF components will result in either a suppressive or facilitative interaction. However, we found that BOLD responses to simultaneous stimulation appeared to reflect simple summation of the neural activity from the individual hemifield conditions. This suggests that the superimposed opposite hemifield representations do not interact. Thus, dual pRFs in albinism likely reflect two co-localized, but functionally independent populations of neurons each of which respond to a single hemifield. This finding is commensurate with psychophysical studies which have shown no clear perceptual interaction between opposite visual hemifields in human albinism.
PubMed: 38853944
DOI: 10.1101/2024.05.26.595603 -
Brain and Nerve = Shinkei Kenkyu No... Jun 2024Unilateral spatial neglect (USN) is a symptom of unilateral brain damage resulting in failure to report sensory phenomena in the contra-lesional space. It is associated... (Review)
Review
Unilateral spatial neglect (USN) is a symptom of unilateral brain damage resulting in failure to report sensory phenomena in the contra-lesional space. It is associated with motor impairment as well as sensory deficits. Recent research suggests that USN, may be caused by a disruption in the interhemispheric balance of the visual attention network. Based on this hypothesis, non-invasive brain stimulation (NIBS), such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), is utilized in the rehabilitation of USN patients. Presently, inhibitory stimulation by continuous theta burst stimulation (cTBS) on contra-lesional parietal cortex are believed to be the most promising method. Conversely, compensation by attentional network of the non-lesioned hemisphere plays an important role in the recovery of USN. Recent imaging studies revealed that functional and structural connectivity of attentional networks within a lesioned hemisphere and between lesioned and non-lesioned hemispheres affects spontaneous recovery and effectiveness of rehabilitation approach such as prism adaptation therapy. These findings are useful in elucidating the pathophysiology of USN and predicting functional outcome. Furthermore, we hope that understanding the pathophysiology will enable the development of new rehabilitation strategies and appropriate treatment selection.
Topics: Humans; Perceptual Disorders; Transcranial Magnetic Stimulation; Transcranial Direct Current Stimulation; Attention
PubMed: 38853505
DOI: 10.11477/mf.1416202674 -
Brain and Nerve = Shinkei Kenkyu No... Jun 2024Unilateral spatial neglect is the failure of brain-damaged patients to report, respond, or orient to novel or meaningful stimuli presented to the contralateral side of... (Review)
Review
Unilateral spatial neglect is the failure of brain-damaged patients to report, respond, or orient to novel or meaningful stimuli presented to the contralateral side of the lesion. This usually involves the right cerebral hemisphere. Neglect presents with no restriction in gaze direction and results in difficulty across various aspects of daily activities, distinguishing it from simple homonymous hemianopia. The basic mechanisms underlying neglect is rightward bias of spatial attention, while non-direction-specific cognitive problems may contribute to clinical expressions of neglect.
Topics: Humans; Perceptual Disorders; Space Perception; Attention; Functional Laterality
PubMed: 38853504
DOI: 10.11477/mf.1416202673 -
Clinical Linguistics & Phonetics Jun 2024Speech training apps are being developed that provide automatic feedback concerning children's production of known target words, as a score on a 1-5 scale. However, this...
Speech training apps are being developed that provide automatic feedback concerning children's production of known target words, as a score on a 1-5 scale. However, this 'goodness' scale is still poorly understood. We investigated listeners' ratings of 'how many stars the app should provide as feedback' on children's utterances, and whether listener agreement is affected by clinical experience and/or access to anchor stimuli. In addition, we explored the association between goodness ratings and clinical measures of speech accuracy; the Percentage of Consonants Correct (PCC) and the Percentage of Phonemes Correct (PPC). Twenty speech-language pathologists and 20 non-expert listeners participated; half of the listeners in each group had access to anchor stimuli. The listeners rated 120 words, collected from children with and without speech sound disorder. Concerning reliability, intra-rater agreement was generally high, whereas inter-rater agreement was moderate. Access to anchor stimuli was associated with higher agreement, but only for non-expert listeners. Concerning the association between goodness ratings and the PCC/PPC, correlations were moderate for both listener groups, under both conditions. The results indicate that the task of rating goodness is difficult, regardless of clinical experience, and that access to anchor stimuli is insufficient for achieving reliable ratings. This raises concerns regarding the 1-5 rating scale as the means of feedback in speech training apps. More specific listener instructions, particularly regarding the intended context for the app, are suggested in collection of human ratings underlying the development of speech training apps. Until then, alternative means of feedback should be preferred.
PubMed: 38853471
DOI: 10.1080/02699206.2024.2355470 -
Brain Research Bulletin Aug 2024An influential model of spatial attention postulates three main attention-orienting mechanisms: disengagement, shifting, and engagement. Early research linked...
An influential model of spatial attention postulates three main attention-orienting mechanisms: disengagement, shifting, and engagement. Early research linked disengagement deficits with superior parietal damage, regardless of hemisphere or presence of spatial neglect. Subsequent studies supported the involvement of more ventral parietal regions, especially in the right hemisphere, and linked spatial neglect to deficient disengagement from ipsilateral cues. However, previous lesion studies faced serious limitations, such as small sample sizes and the lack of brain-injured controls without neglect. Additionally, some studies employed symbolic cues or used long cue-target intervals, which may fail to reveal impaired disengagement. We here used a machine-learning approach to conduct lesion-symptom mapping (LSM) on 89 patients with focal cerebral lesions to the left (LH) or right (RH) cerebral hemisphere. A group of 54 healthy participants served as controls. The paradigm used to uncover disengagement deficits employed non-predictive cues presented in the visual periphery and at short cue-target intervals, targeting exogenous attention. The main factors of interest were group (healthy participants, LH, RH), target position (left, right hemifield) and cue validity (valid, invalid). LSM-analyses were performed on two indices: the validity effect, computed as the absolute difference between reaction times (RTs) following invalid compared to valid cues, and the disengagement deficit, determined by the difference between contralesional and ipsilesional validity effects. While LH patients showed general slowing of RTs to contralesional targets, only RH patients exhibited a disengagement deficit from ipsilesional cues. LSM associated the validity effect with a right lateral frontal cluster, which additionally affected subcortical white matter of the right arcuate fasciculus, the corticothalamic pathway, and the superior longitudinal fasciculus. In contrast, the disengagement deficit was related to damage involving the right temporoparietal junction. Thus, our results support the crucial role of right inferior parietal and posterior temporal regions for attentional disengagement, but also emphasize the importance of lateral frontal regions, for the reorienting of attention.
Topics: Humans; Male; Female; Middle Aged; Parietal Lobe; Attention; Aged; Functional Laterality; Adult; Reaction Time; Frontal Lobe; Perceptual Disorders; Cues; Space Perception; Brain Injuries
PubMed: 38852652
DOI: 10.1016/j.brainresbull.2024.111003 -
Psychiatria Polska Feb 2024Eidetic images are a relatively rare phenomenon in the practice of a psychiatrist. They are described in the category of perception disorders as images or memories...
Eidetic images are a relatively rare phenomenon in the practice of a psychiatrist. They are described in the category of perception disorders as images or memories which, thanks to their plasticity, vividness and detail, are very similar to the currently experienced sensory perceptions. However, it should be remembered that their occurrence is not associated with any mental disorders, and they are also observed in some healthy people. This paper presents a case report of a patient with complaints about "voiced," plastic images - the course of his psychiatric hospitalization and the psychological diagnostics carried out at that time. The authors point out the difficulties in differentiating, first of all, with auditory pseudo-hallucinations and make an attempt at psychopathological classification of the patient's symptoms. The discussion on possible disease mechanisms of this phenomenon is based on reports as well as research on the phenomenon of imagination and eidetic perceptions, and the aim of this study is to draw the attention of diagnosticians to the category of psychological phenomena with an eidetic character, which may allow them to avoid incorrect recognition of them as an element of psychotic disorders of perception.
Topics: Humans; Male; Adult; Hallucinations; Psychotic Disorders
PubMed: 38852189
DOI: 10.12740/PP/159446 -
International Journal of Language &... Jun 2024Speech and language therapists (SLTs) regularly use phonetic transcription to record and analyse typical and disordered speech. Phonetic transcription is highly...
BACKGROUND
Speech and language therapists (SLTs) regularly use phonetic transcription to record and analyse typical and disordered speech. Phonetic transcription is highly demanding of auditory perceptual skills so researchers are sceptical about its accuracy and reliability. The literature describes how phonetic transcription is prone to auditory illusions and biases, such as a preference to transcribe speech sounds from the transcriber's own language. Few empirical research studies have calculated agreement amongst transcribers where a range of agreement scores have been reported (51%-97%). There is a consensus that agreement rates decrease as phonetic detail increases. Vowels and consonants are characterised by different perceptual features within the International Phonetic Alphabet (IPA) so they may differ in agreement rates, and thus far there is contradictory evidence as to whether vowels or consonants are more agreed upon. Transcription agreement studies to date have most commonly recruited phoneticians rather than SLTs so further research is warranted to determine transcription agreement amongst SLTs and its impact on clinical practice.
AIMS
The study's primary aim was to calculate agreement scores from a group of English-speaking SLTs who transcribed disordered speech samples in an ecologically valid setting. The study also sought to contribute to the pre-existing contradictory evidence base regarding whether vowels or consonants may be more agreed upon by comparing their agreement scores. The researcher aimed to comment on SLTs' use of diacritics and non-native speech symbols (symbols not included in the English phonetic inventory) in terms of their frequency and agreement of use. By analysing transcriptions, the study aimed to discuss the impact transcription variability has on speech sound error patterns and thus its impact on clinical decision-making such as diagnosis, choice of intervention and therapy targets.
METHODS
Twelve paediatric SLTs were recruited via a convenience sample at two National Health Service trusts, two of whom were specialists in Speech Sound Disorders (SSDs). Participants transcribed 16 words from a video of a boy with disordered speech completing the Diagnostic Evaluation of Articulation and Phonology (DEAP, Dodd et al., 2006) from a telehealth appointment. The use of diacritics and non-English IPA symbols were manually analysed. A classic agreement score was calculated for each target word using a Python script, and then for vowels and consonants in isolation. Datasets were manually analysed to determine whether differences in transcription resulted in the identification of different speech sound error patterns. The researcher considered the implications this had within clinical practice.
RESULTS
The average classic agreement score was 56.3%. Consonants were more agreed upon than vowels with agreement scores of 62.8% and 48.6%, respectively. Nine participants (75%) used diacritics (most commonly length marks) and eight participants (67%) transcribed non-native IPA symbols at least once in their datasets, but generally with low frequencies and agreements amongst their use. Transcriptions captured the occurrence of typical and atypical error patterns but only three error patterns, out of the 20 identified, were present in all 12 participants' transcriptions.
CONCLUSIONS
The agreement score of 56.3% questions the accuracy and reliability of transcription amongst SLTs which is an essential skill of the profession. The findings highlight SLTs should be more cautious of interpreting vowels than consonants given lower agreement rates. The frequency of use of non-native symbols and diacritics was relatively low which could reflect a low accuracy of their use or reduced confidence in transcribing these. The study discussed how variations in transcriptions can impact phonological and phonetic analysis, which in turn can influence clinical decision-making such as diagnosing SSDs, selecting further diagnostic assessments and choosing therapy targets and interventions. The Royal College of Speech and Language Therapists-endorsed transcription guidelines (Child Speech Disorder Research Network, 2017) could be revised to convey realistic expectations of SLTs' transcription skills, or SLTs should be offered more training to improve transcription skills to meet current expectations. Other suggestions to improve transcription accuracy are discussed such as via instrumental methods, yet these come with their own limitations such as practicality, costs and need for specialist training.
WHAT THIS PAPER ADDS
What is already known on this subject Phonetic transcription is highly demanding of human perceptual skills, and researchers are sceptical about its reliability. There are few empirical research studies calculating agreement amongst transcribers, and a range of agreement scores have been reported (51%-97%) dependent on the research conditions. Research mostly involves experienced transcribers (e.g., phoneticians) rather than speech and language therapists (SLTs), a profession expected to regularly use phonetic transcription to record and analyse typical and disordered speech. What this study adds to existing knowledge A range of transcription agreement scores have been reported in previous studies, mainly comparing pairs or small groups of specialist transcribers rather than SLTs. This study provides an agreement score of 56.3% when a group of 12 SLTs transcribed a disordered speech sample in an ecologically valid setting (where speech samples were taken from a real-life speech sound assessment over a telehealth appointment using the Diagnostic Evaluation of Articulation and Phonology). The study found consonants are more agreed upon than vowels, adding to the contradictory evidence base. Unlike other studies, the researcher analysed transcriptions to identify error patterns to examine the impact that transcription variation has on clinical decision-making. What are the potential or actual clinical implications of this work? The researcher questions whether SLTs are meeting the expectations of 'accurate transcription' as listed by the Royal College of Speech and Language Therapists (RCSLT) endorsed transcription guidelines (Child Speech Disorder Research Network, 2017) given the relatively low agreement score of 56.3%. The study also questions the reliability of the use of diacritics and non-English International Phonetic Alphabet (IPA) symbols and whether SLTs should be expected to use these due to perceptual limitations. Twenty phonological processes emerged from the datasets, only three of which were agreed upon across all 12 participants. The researcher therefore discusses how transcription variations could result in different diagnoses, therapy targets and interventions choices. The paper suggests more training is required to enhance transcription accuracy, and also considers the appropriateness of utilising instrumental methods whilst recognising its limitations such as feasibility, costs and specialist training needs.
PubMed: 38850167
DOI: 10.1111/1460-6984.13043