Biomedical subjects

Francis P McGlone

Publications and source records attributed to Francis P McGlone.

5 recordsLinked to original sources

PubMed2005

Changes in neural complexity of the EEG during a visual oddball task.

OBJECTIVE: Neural complexity (C(N)) was introduced by Tononi et al. in an information-theoretic framework to capture the balance between functional specialisation and integration in the brain. We hypothesised that C(N) should vary during cognitive processing, specifically during an oddball task. METHODS: In 11 normal human subjects, we recorded from groups of EEG electrodes in the frontal (F), central-parietal (CP) and occipito-temporal (OT) regions during a visual oddball reward conditioning task and calculated C(N) in each region. Three types of visual stimulus (abstract shapes, called neutral, reward and penalty) were presented randomly in three blocks of trials. During the first block, subjects did not know the significance of the stimulus shapes. For the subsequent (conditioning) blocks, subjects were informed that whenever they saw reward or penalty patterns, they would win or lose money, respectively. RESULTS: In regions CP and OT, C(N) was significantly larger in reward and penalty trials than in neutral during all blocks. During a trial, significant changes in C(N) occurred around the ERP peaks N1 and P300 and the effects of reward conditioning on C(N) could be distinguished from penalty. CONCLUSIONS: Our findings support the above hypothesis, indicating that C(N) correlates with both the sensory and cognitive components of stimulus processing. SIGNIFICANCE: This study extends the scope of C(N) in the analysis of cognitive processing.

Adult↗

PubMed2003

Orienting of attention and Parkinson's disease: tactile inhibition of return and response inhibition.

There is growing evidence for cognitive impairments in Parkinson's disease (PD), including in the orienting of attention and inhibition of return (IOR). IOR refers to the slowing of a response to a target stimulus presented in the same location as a previous stimulus. While some researchers have reported normal levels of visual IOR in PD patients using cue-target tasks, others have reported significant reductions in IOR in this patient group. However, the inhibitory effects observed in cue-target tasks may reflect non-ocular response inhibition associated with withholding a response from the cue stimulus, rather than attentional or oculomotor processes. Many researchers working with normal participants have circumvented this confound by using a target-target task, in which a response is made to all peripheral stimuli. Here, we compared IOR measured in cue-target and target-target tasks, using tactile rather than visual stimuli. Both the PD and the control groups exhibited significant inhibitory effects in the cue-target task, but only the control group exhibited significant IOR in the target-target task. Our results demonstrate a reduction, or elimination, of IOR in PD and this change may have been underestimated in previous studies, in which methodologically flawed cue-target tasks were used. This reduction in IOR may reflect impaired inhibitory processes or hyper-reflexive orienting in parkinsonian patients.

Aged↗

PubMed2003

Intra- and interactive touch on the face.

Experiments were performed in which the subjective size of steel balls was judged by the method of absolute magnitude estimation (AME). The balls were rolled actively ("scripting") by the right index finger pad of the subject over the passively receiving areas of the face, namely the forehead, cheek and the vermilion border of the lower lip. These areas were stimulated on the subject's own person (intra-active touch), on another person's face (interactive touch) and by another person upon the face of the subject (interactive touch). Results indicate that size perception appears to be governed primarily by the mechanical characteristics of the stimuli, including the balls and the sites on the face. When the subject's finger was used to script upon another's face, there were significant differences among or between the sites. When another person scripted upon the subject's face there were no significant differences among any of the sites. The results are discussed considering mode of stimulation and tissue mechanics.

Cheek↗

PubMed2003

The role of spatial attention in the processing of facial expression: an ERP study of rapid brain responses to six basic emotions.

To investigate the time course of emotional expression processing, we recorded ERP responses to stimulus arrays containing neutral versus angry, disgusted, fearful, happy, sad, or surprised faces. In one half of the experiment, the task was to discriminate emotional and neutral facial expressions. Here, an enhanced early frontocentral positivity was elicited in response to emotional as opposed to neutral faces, followed by a broadly distributed positivity and an enhanced negativity at lateral posterior sites. These emotional expression effects were very similar for all six basic emotional expressions. In the other half of the experiment, attention was directed away from the faces toward a demanding perceptual discrimination task. Under these conditions, emotional expression effects were completely eliminated, demonstrating that brain processes involved in the detection and analysis of facial expression require focal attention. The face-specific N170 component was unaffected by any emotional expression, supporting the hypothesis that structural encoding and expression analysis are independent processes.

Adolescent↗

PubMed2002

Selective attention to pain: a psychophysical investigation.

Laboratory research suggests that the processing of painful stimuli can be modulated by selective attention to a particular sensory modality. However, alternative accounts for previous findings remain possible in terms of task-switching and spatial attention effects. In the present study, we examined whether attention can be selectively directed to the pain modality in order to facilitate the processing of the sensory-discriminative aspects of painful laser heat stimuli when these alternatives were ruled out. Participants made speeded spatial discrimination responses to an unpredictable sequence of painful laser heat and visual stimuli presented on the left forearm. On each trial, a symbolic cue predicted the likely modality for the upcoming target on the majority of trials. Participants responded more rapidly when the target was presented in the expected as opposed to the unexpected modality, demonstrating that selective attention can modulate the processing of painful stimuli. These findings are discussed in relation to contemporary theories of crossmodal attention and multisensory information-processing.

Attention↗