ANIMAL	Macaca fascicularis
PREP	anesthetized (sufentanil), paralyzed (vecuronium)
DATA TYPE	extracellular spike times
CELL TYPE	parvo- and magnocellular cells
N	53 cells

Stimulus

The stimulus was a drifting sinusoidal grating at 100% contrast presented in a circular aperture that covered a region larger than the classical center and surround of each LGN cell. Spatial frequency was fixed at the optimal value. Temporal frequency (TF) was varied from trial to trial from 0.2 to 25 Hz in octave steps. For trials with the parameter ampl set to zero, no stimulus appeared and the response represents the spontaneous firing to a mean gray field. During data collection, the non-dominant eye was occluded with a black, non-reflective surface.

The distance from the retina to the video monitor is specified in centimeters in the header of each file as scrdist. The monitor had 33 pixels/cm.

The units of temporal frequency, tf, are 10.24 times cycles/sec, e.g. tf 128 is 12.5 Hz. The variable cycles specifies the number of cycles that the grating drifted on each trial, and is typically related to tf.

Caveats. Quality of single neuron isolation in the LGN is sometimes affected by the heart beat, and some spikes may be absent in correlation with the heart beat. Small eye movements may occur, even though the eye muscles are paralyzed. Phase shifts in the rasters may indicate a small change in eye position which affects the time at which the drifting grating excites the cell. For example, in 474l005.p02 it is likely that a small change in eye position occurred roughly between trials 11 and 12.

Electrophysiological Methods

Bair W, Cavanaugh JR, Smith MA, Movshon JA (2002) The timing of response onset and offset in macaque visual neurons. J Neurosci 22:3189-3205.

Published analyses

None.