AI Article Synopsis
- Understanding how the brain processes sensory information involves connecting physical stimuli to both how decisions are made and neuronal activity.
- In an experiment with head-fixed rats, it was found that they could distinguish between two vibration frequencies (90 Hz and 60 Hz) only when the vibration intensity changed with frequency.
- By manipulating the amplitude of the vibrations, researchers discovered that when the intensity was equal, the rats could not tell the difference between the frequencies, indicating that the brain relies on the mean absolute velocity of the vibrations for perception.
Article Abstract
Understanding the neural code underlying perception requires the mapping of physical stimulus parameters to both psychophysical decisions and neuronal responses. Here, we employed a novel psychophysical task in head-fixed rats to measure discriminability of vibrotactile whisker deflections. Rats could discriminate 90 Hz from 60 Hz pulsatile stimuli if stimulus intensity covaried with frequency. To pin down the physical parameters used by the rats to discriminate these vibrations, we manipulated stimulus amplitude to arrive at pairs of nondiscriminable stimuli. We found that vibrations matched in intensity (measured as mean absolute velocity), but differing in frequency, were no longer discriminable. Recordings of trigeminal ganglion neurons revealed that the distribution of neurometric sensitivities based on spike counts, but not interspike intervals, matched the rats' inability to discriminate intensity-matched stimuli. In conclusion, we suggest that stimulus mean absolute velocity, encoded in primary afferent spike counts, plays a prominent role for whisker-mediated perception.
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| http://dx.doi.org/10.1016/j.neuron.2010.02.007 | DOI Listing |
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