TOUCH AND KINESTHESIS 



409 



FIG. 1 2. Responses of a single neuron of ventrobasal thalamic nuclear complex of the cat to elec- 

 trical stimulation of skin of the contralateral foreleg. The stimuli were delivered at diflferent fre- 

 quencies per second which are indicated by the numbers on the left. Note reduction of modal \alue 

 and equilibration of response with increasing frequencies of stimulation, and the early silent period. 

 Stimulus artefacts are not visible. [From Mountcastle, V. B & | E. Rose, unpublished observa- 

 tions.] 



tion is yet available which permits a complete descrip- 

 tion of the sequential changes in neural events brought 

 about by a natural stimulus in a completelv unanes- 

 thetized animal. Underlying studies of this type is the 

 assumption that perception of a local peripheral 

 event depends in the first instance upon a local zone 

 of cortical activity of abrupt onset, and that percep- 

 tion of more complex forms of stimuli (e.g. two-point 

 discrimination, form and contoiu" recognition, etc.) 

 may depend upon the interaction of many such zones 

 of activity. One of the problems in sensory physiology 

 at the present time is to determine in some detail the 

 patterns of cortical activity evoked by peripheral 

 stimuli of some spatial and temporal complexity. It 

 seems likely that single unit studies will advance the 

 solution of this problem. 



KINESTHESIS OR SENSE OF POSITION .^ND 

 MOVEMENTS OF JOINTS 



It is apparent that information concerning the 

 orientation of the bod\' in space and of the spatial 

 relations between its parts depends upon afferent 

 inputs from both somatic sensory and \estibular 

 receptors as well as from the visual apparatus. The 

 thesis is presented here that the somatic sensory com- 

 ponent, which we shall refer to as kinesthesis or the 

 sense of position and movement of the joints, depends 



FIG. 13. Responses of a single neuron of the ventrobasal 

 thalamic nuclear complex of the cat to electrical stimulation of 

 the skin near the first digit of the contralateral forepaw, de- 

 livered at different frequencies. Note reduction of modal value 

 as frequency increases from 10 to 20 or more per sec. At 

 frequency of 40 per sec, or higher, the neuron responded to the 

 first stimulus of a train and failed to respond thereafter: 

 'cut-off' characteristic. Small deflections are stimulus artefacts. 

 [From Mountcastle, 'V. B. & J. E. Rose, unpublished observa- 

 tions.] 



