Sensory Hand

Author:

Vernon b Mountcastle

Summary:

* Movement is the facilitating agent for complex tactile experiences.

the ability of the brain to integrate successive patterns of input to create a perceptual whole. The intra-cortical processing times of 80-100 ms for each pattern. Mechanical oscillations can be delivered to the skin. Humans can sense over frequency range from about 5 - 600 Hz. Frequencies in the range of 5 -50 Hz evoke a localized stimulus site. Increasing the frequencies changes the sensory experience gradually to the deep, spreading and poorly localized hum.

* Weber Law - Ratio of the perceivable change in tactile stimuli and the magnitude of stimuli is constant.

* Fechner law - Extending the Weber's law, Fechner quantified the sensation as logarithmic function of the magnitude of the stimulus.

Chapter 11

Localization error is minimum at finger pad and gradually increase towards proximal and palm.

(Schady & Torebjork, 1983) - point localization and Wheat, et al - tactile localization experiment on hand - separation threshold to distinguish a point from sphere of radius to the object of same radius. The human receptiveness increases with time. Sensitivity to stimuli increased in 300ms.

Movement and direction - all the stimuli reaching hand are sensed by scanning movements combine lateral movement and skin stretch.

Flutter vibration - experiments on frequency change detections and change detection thresholds.