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Biomedical subjects

Jason D Warren

Publications and source records attributed to Jason D Warren.

At least 19 recordsLinked to original sources
PubMed2006

Music and the brain: disorders of musical listening.

The study of the brain bases for normal musical listening has advanced greatly in the last 30 years. The evidence from basic and clinical neuroscience suggests that listening to music involves many cognitive components with distinct brain substrates. Using patient cases reported in the literature, we develop an approach for understanding disordered musical listening that is based on the systematic assessment of the perceptual and cognitive analysis of music and its emotional effect. This approach can be applied both to acquired and congenital deficits of musical listening, and to aberrant listening in patients with musical hallucinations. Both the bases for normal musical listening and the clinical assessment of disorders now have a solid grounding in systems neuroscience.

Auditory Perception↗
PubMed2005

Sounds do-able: auditory-motor transformations and the posterior temporal plane.

Accumulating evidence in humans and non-human primates implicates the posterior superior temporal plane (STP) in the processing of both auditory spatial information and vocal sounds. Such evidence is difficult to reconcile with existing accounts of the primate auditory brain. We propose that the posteromedial STP generates sequenced auditory representations by matching incoming auditory information with stored templates. These sequenced auditory representations are subsequently used to constrain motor responses. We argue for a re-assessment of the much-debated dorsal auditory pathway in terms of its generic behavioral role as an auditory "do" pathway.

Animal Communication↗
PubMed2005

Magnetic resonance imaging signatures of tissue pathology in frontotemporal dementia.

BACKGROUND: The pathologic substrates of frontotemporal dementia (FTD) are difficult to predict in vivo. OBJECTIVE: To determine whether different pathologic substrates of FTD have distinct patterns of regional atrophy on magnetic resonance imaging (MRI). DESIGN: Retrospective case study. SETTING: The Institute of Neurology, University College London, and the Institute of Psychiatry, King's College London. Patients Twenty-one cases of FTD selected on pathologic grounds (9 with ubiquitin-positive [tau- and alpha-synuclein-negative] inclusions [FTD-U], 7 with Pick disease [PiD], and 5 with familial FTD with tau exon 10+16 mutations [tau exon 10+16]) and 20 healthy controls were studied. MAIN OUTCOME MEASURES: Patterns of gray matter atrophy in each group as assessed by voxel-based morphometry (VBM) and a blinded visual assessment of each MRI study. RESULTS: All pathologic substrates were associated with atrophy that involved the inferior and medial temporal and inferior frontal lobes. Additionally, specific VBM signatures were identified for each subgroup: FTD-U was associated with asymmetric (left > right) temporal lobe atrophy, PiD was associated with severe dorsolateral bifrontal atrophy, and tau exon 10+16 was associated with asymmetric (right > left) medial temporal lobe atrophy. The VBM findings were supported by blinded visual assessment. CONCLUSION: These findings suggest that MRI patterns of regional gray matter atrophy constitute signatures of tissue pathology in FTD.

Atrophy↗
PubMed2005

Computation of tactile object properties requires the integrity of praxic skills.

We describe a series of experiments to examine the tactile identification of objects over the course of neurological recovery in a patient with an intracerebral haemorrhage involving the left inferior and superior parietal lobe. Tactile agnosia in this case involved the ipsilesional as well as the contralesional hand, allowing us to observe the effects of dominant parietal lobe damage without the confounding effects of hemiparesis. The findings demonstrate that both apraxia and tactile apperceptive agnosia may result from a unilateral lesion involving the left parietal lobe. The findings further suggest that the computation of macro-geometrical and micro-geometrical tactile object properties is dissociable. Macro-geometrical tactile analysis depends on intact programming of exploratory hand movements, while the role of such movements in micro-geometrical analysis is less clear.

Adult↗
PubMed2004

Cortical processing of complex sound: a way forward?

The organization of the cortical auditory system remains controversial. In particular, the extent to which there is regional specialization in the cortical processing of complex sound is unclear. Here, we ask whether we are currently asking the right questions of auditory cortex, or using the appropriate techniques to do so. A key factor that will promote such understanding in the future will be increasing dialogue between workers using electrophysiological recording methods to assess the response properties of single neurons and those using imaging techniques to map regional organization. In the future, further insights will be obtained by efforts to test hypotheses developed on the basis of one approach by the use of the other. Imaging can tell the neurophysiologists where to look, and work on single neurons can constrain network models based on imaging. There is a crucial need for better understanding of the anatomy of the auditory cortex in different species and for comparative studies that will underpin both approaches.

Acoustic Stimulation↗
PubMed2004

What is an auditory object?

Objects are the building blocks of experience, but what do we mean by an object? Increasingly, neuroscientists refer to 'auditory objects', yet it is not clear what properties these should possess, how they might be represented in the brain, or how they might relate to the more familiar objects of vision. The concept of an auditory object challenges our understanding of object perception. Here, we offer a critical perspective on the concept and its basis in the brain.

Acoustic Stimulation↗
PubMed2004

Voxel-based morphometry in tau-positive and tau-negative frontotemporal lobar degenerations.

BACKGROUND: The identification of specific, diagnostically useful predictors of protein dysfunction in the frontotemporal lobar degenerations (FTLD) is a problem of great clinical and biological interest. Correlations between regional patterns of tissue loss and specific proteinopathies have not been established. OBJECTIVE: Specific brain imaging correlates of protein tau dysfunction were sought using voxel-based morphometry in FTLD subgroups with and without tau pathology. METHODS: Seventeen patients with pathologically or genetically confirmed diagnoses of FTLD who had undergone volumetric brain magnetic resonance imaging (MRI) were identified retrospectively and tau-positive (n = 9) and tau-negative (n = 8) subgroups were defined. MRI data were compared with healthy age- and sex-matched controls using voxel-based morphometry implemented in a statistical parametric mapping software package. RESULTS: Compared with controls, tau-positive and tau-negative subgroups had extensive common areas of regional brain atrophy predominantly affecting the frontal and anterior temporal lobes. No specific brain imaging features were identified for either subgroup. CONCLUSION: Patterns of frontotemporal atrophy do not predict the presence or absence of tau pathology; conversely, different immunohistochemical profiles are associated with similar patterns of regional vulnerability to neuronal loss in FTLD.

Dementia↗
PubMed2003

Brainstem myoclonus in generalised tetanus.

Electrophysiological studies of stimulus sensitive myoclonus in a man with generalised tetanus revealed features characteristic of hyperekplexia or brainstem myoclonus.

Brain Stem↗
PubMed2003

Microvasculitic paraproteinaemic polyneuropathy and B-cell lymphoma.

Microvasculitis may play a greater part in the pathogenesis of paraproteinaemic neuropathies than is generally recognised, producing tissue destruction by convergent immune and physical mechanisms. We present a patient with a clinical syndrome of mononeuritis multiplex and a circulating IgM lambda paraprotein, in whom bone marrow aspiration revealed a lymphoplasmacytoid lymphoma. Microvasculitic changes were present in the first nerve biopsy, and the second showed extensive destruction of neural architecture and deposition of IgM-related material. A 2-stage pathogenic cascade is postulated and explored with a review of the relevant literature.

Aged↗
PubMed2003

Nothing to say, something to sing: primary progressive dynamic aphasia.

We describe a 76-year-old man (ADY) with dynamic aphasia in the setting of a degenerative frontal lobe dementia: primary progressive dynamic aphasia. He displayed a striking paucity of propositional speech despite intact speech production, and preserved singing and prosody. Vocal expression in the verbal and musical domains was investigated in a series of neuropsychological experiments based on novel language and musical tasks that were designed to establish the nature and specificity of the verbal output deficit. The features of the language disorder indicated that the speech output pathway was disrupted at the early stage of generation of a new pre-verbal message. In contrast, tests of musical output demonstrated that the generation of new musical ideas was unimpaired. The domain-specificity of dynamic aphasia may result from the disruption of specific cognitive processes necessary for the creation of verbal messages, as well as selective damage of brain regions involved in language production.

Aged↗
PubMed2003

Analyzing pitch chroma and pitch height in the human brain.

The perceptual pitch dimensions of chroma and height have distinct representations in the human brain: chroma is represented in cortical areas anterior to primary auditory cortex, whereas height is represented posterior to primary auditory cortex.

Auditory Cortex↗
PubMed2002

A common cortical substrate activated by horizontal and vertical sound movement in the human brain.

Perception of movement in acoustic space depends on comparison of the sound waveforms reaching the two ears (binaural cues) as well as spectrotemporal analysis of the waveform at each ear (monaural cues). The relative importance of these two cues is different for perception of vertical or horizontal motion, with spectrotemporal analysis likely to be more important for perceiving vertical shifts. In humans, functional imaging studies have shown that sound movement in the horizontal plane activates brain areas distinct from the primary auditory cortex, in parietal and frontal lobes and in the planum temporale. However, no previous work has examined activations for vertical sound movement. It is therefore difficult to generalize previous imaging studies, based on horizontal movement only, to multidimensional auditory space perception. Using externalized virtual-space sounds in a functional magnetic resonance imaging (fMRI) paradigm to investigate this, we compared vertical and horizontal shifts in sound location. A common bilateral network of brain areas was activated in response to both horizontal and vertical sound movement. This included the planum temporale, superior parietal cortex, and premotor cortex. Sounds perceived laterally in virtual space were associated with contralateral activation of the auditory cortex. These results demonstrate that sound movement in vertical and horizontal dimensions engages a common processing network in the human cerebral cortex and show that multidimensional spatial properties of sounds are processed at this level.

Acoustic Stimulation↗
PubMed2002

Perception of sound-source motion by the human brain.

We assessed the human brain network for sound-motion processing using the same virtual stimulus in three independent functional imaging experiments. All experiments show a bilateral posterior network of activation, including planum temporale (PT) and parieto-temporal operculum (PTO). This was demonstrated in contrasts between sound movement and two control conditions: externalized stationary stimuli (in the midline or to the side of the head) and midline sounds within the head with similar spectro-temporal structure. We suggest specific computational mechanisms in PT for disambiguation of the intrinsic spectro-temporal features of a sound and the spectro-temporal effect of sound movement. The results support the existence of a posteriorly directed temporo-parietal pathway for obligatory perceptual processing of sound-source motion.

Adult↗
PubMed2002

Corticobasal degeneration syndrome with basal ganglia calcification: Fahr's disease as a corticobasal look-alike?

A 57-year-old man with a 5-year history of progressive left-sided rigidity and apraxia had extensive bilateral calcification of basal ganglia, centrum semiovale, dentate nuclei, and cerebellar white matter on brain imaging. The case is an example of radiological Fahr's disease accompanying a clinical syndrome of corticobasal degeneration. Possible pathogenetic and nosological implications of this association are discussed.

Basal Ganglia Diseases↗