Organization of Human Auditory Cortex: Responses to Frequency Modulated Sounds

Functional Magnetic Resonance Imaging (fMRI) was used to investigate the extent, magnitude and patterns of brain activity in response to frequency-modulated sounds. We examined this by manipulating the direction (rise vs. fall) and the rate (fast vs. slow) of a series of iterated rippled noise (IRN) bursts. Participants were presented with auditory stimuli while functional images of the cortex were obtained. Univariate analyses revealed more widespread activation within auditory cortex in response to frequency-modulated sweeps compared to steady-state sounds. Furthermore, multivoxel pattern analysis (MVPA) was used to determine whether regions within auditory cortex were involved in feature-specific encoding. The pattern of activity within auditory cortex showed a high degree of consistency for the rate dimension, suggesting this pattern of activity infers representational information. Additionally, activity patterns for direction were not distinguishable, which suggests this coding occurs over a neural activity pattern not distinguishable at the level of the BOLD response

Do Different Music Genres Differentially Affect Autonomic Activity? How Music and Sound Affect Autonomic Activity Aroused by Visual Stimuli

The primary researcher sought to determine whether different genres of music would differentially influence measures of autonomic nervous system activity (heart rate, galvanic skin response) while viewing visual stimuli in a sample of college students. All participants listened to the same songs and music genres and viewed the same International Affective Picture System (IAPS) images. Autonomic nervous system activity was recorded by attaching electrodes to participants\u27 non-dominant hand and torso. Music order presentation and picture order presentation were randomly determined by E-Prime. Heart rate and skin conductance responses were both significant, with melodic metal music inducing greater intensity of responses for both, and an interaction effect was revealed for heart rate minimum and picture type. Findings show that different genres of music differentially affect autonomic nervous system activity, and that these effects are further influenced by stimuli valence (positive, negative, neutral). These results reveal that different genres of music have different effects on autonomic nervous system activity, and that such effects cannot be explained by musical preference

Swayed by sound: sonic guidance as a neurorehabilitation strategy in the cerebellar ataxias

Cerebellar disease leads to problems in controlling movement. The most common difficulties are dysmetria and instability when standing. Recent understanding of cerebellar function has expanded to include non -motor aspects such as emotional, cognitive and sensory processing. Deficits in the acquisition and processing of sensory information are one explanation for the movement problems observed in cerebellar ataxia. Sensory deficits result in an inability to make predictions about future events; a primary function of the cerebellum. A question therefore, is whether augmenting or replacing sensory information can improve motor performance in cerebellar disease. This question is tested in this thesis by augmenting sensory information through the provision of an auditory movement guide.A variable described in motor control theory (tau) was used to develop auditory guides that were continuous and dynamic. A reaching experiment using healthy individuals showed that the timing of peak velocity, audiomotor coordination accuracy, and velocity of approach, could be altered in line with the movement parameters embedded in the auditory guides. The thesis then investigated the use of these sonic guides in a clinical population with cerebellar disease. Performance on neurorehabilitation exercises for balance control was tested in twenty people with cerebellar atrophy, with and without auditory guides. Results suggested that continuous, predictive, dynamic auditory guidance is an effective way of improving iii movement smoothness in ataxia (as measured by jerk). In addition, generating and swaying with imaginary auditory guides was also found to increase movement smoothness in cerebellar disease.Following the tests of instantaneous effects, the thesis then investigated the longterm consequences on motor behaviour of following a two -month exercise with auditory guide programme. Seven people with cerebellar atrophy were assessed pre - and post -intervention using two measures, weight -shifting and walking. The results of the weight -shifting test indicated that the sonic -guide exercise programme does not initiate long -term changes in motor behaviour. Whilst there were minor, improvements in walking, because of the weight -shifting results, these could not be attributed to the sonic guides. This finding confirms the difficulties of motor rehabilitation in people with cerebellar disease.This thesis contributes original findings to the field of neurorehabilitation by first showing that on -going and predictive stimuli are an appropriate tool for improving motor behaviour. In addition, the thesis is the first of its kind to apply externally presented guides that convey continuous meaningful information within a clinical population. Finally, findings show that sensory augmentation using the auditory domain is an effective way of improving motor coordination in some forms of cerebellar disease