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Biomedical subjects

T W Picton

Publications and source records attributed to T W Picton.

8 recordsLinked to original sources
PubMed1979

Evoked potential correlates of human information processing.

The late positive component (P3) of the feedback evoked potential was investigated in two tasks: the detection of near-threshold auditory stimuli, and the estimation of 1 s time intervals. When the intensity or probability of the threshold stimuli was varied in the detection task, it became apparent that the feedback P3 was related to the 'contingent probability' of confirming or disconfirming feedback given a particular response. In the time-estimation task the relative probabiliti-s of confirming and disconfirming feedback were altered by changing the time-window wherein a response was judged correct. In these experiments it was found that the feedback P3 component was highly dependent upon the probability of the feedback, and relatively independent of its confirming or disconfirming meaning. With decreasing probability of the feedback stimuli, the P3 component became larger, later, and somewhat more frontal.

Auditory Perception↗
PubMed1979

Brainstem evoked potentials to tonepips in notched noise.

Notched noise can be used to mask the frequency spread of acoustic energy in the brief tonepips that are used to elicit brainstem evoked potentials. Brainstem responses to tonepips and notched noise can therefore be used to evaluate auditory thresholds at particular frequencies. These thresholds are more frequency-specific than those obtained using tonepips alone, and are accurate to within 20 dB of the conventional audiometric thresholds.

Acoustic Stimulation↗
PubMed1978

Human auditory sustained potentials. I. The nature of the response.

In response to a sustained toneburst a negative baseline shift can be recorded from the human fronto-central scalp regions with an onset latency of approximately 150 msec. This auditory sustained potential is distinct both in its scalp distribution and in its stimulus relationships from the transient response occurring at the onset or offset of the toneburst. It differs from the contingent negative variation in that it can occur in the absence of attention or during sleep. Attention to the auditory stimulus can increase the amplitude of the sustained potential, possibly through the addition of an extra negative potential related to auditory expectancy or uncertainty.

Adolescent↗
PubMed1978

Human auditory sustained potentials. II. Stimulus relationships.

The auditory sustained potential recorded from the human scalp increases in amplitude with increasing stimulus intensity. At rapid rates of stimulus presentation its amplitude decreases but proportionately less so than the amplitude of the transient onset auditory evoked potential. The frequency specificity of this rate effect is complex, suggesting that there may be two underlying components of the scalp-recorded auditory sustained potential. The amplitude of the auditory sustained potential is smaller when the tonal frequency of the stimulus is higher. With prolonged stimulus durations there is some adaptation of the amplitude of the auditory sustained potential. This potential is larger in amplitude when sounds are presented binaurally than monaurally, and has a symmetrical coronal scalp distribution that is unaffected by the ear of stimulation.

Acoustic Stimulation↗
PubMed1976

Evoked potential audiometry.

A large number of different components of the auditory evoked potential can be recorded from the human scalp using averaging techniques. It is now possible to evaluate with such evoked potential measurements the functioning of the entire human auditory system from the hair cell receptors to the association areas of cortex. This multiplicity of evoked potential components is important clinically since any one component measurement may be the most appropriate for a certain subject at a certain time, and also because the replication of objective audiological findings using more than one testing method allows greater confidence in the results. As well as providing an accurate means of determining the extent of a hearing loss, evoked potential studies can also provide information concerning the type and location of such a defect.

Adult↗