Quick search Find article
Quick search
Find article

Fast wave propagation in auditory cortex of an awake cat using a chronic microelectrode array*

Russell S Witte1, Patrick J Rousche2 and Daryl R Kipke1

Show affiliations


We investigated fast wave propagation in auditory cortex of an alert cat using a chronically implanted microelectrode array. A custom, real-time imaging template exhibited wave dynamics within the 33-microwire array (3 mm2) during ten recording sessions spanning 1 month post implant. Images were based on the spatial arrangement of peri-stimulus time histograms at each recording site in response to auditory stimuli consisting of tone pips between 1 and 10 kHz at 75 dB SPL. Functional images portray stimulus-locked spiking activity and exhibit waves of excitation and inhibition that evolve during the onset, sustained and offset period of the tones. In response to 5 kHz, for example, peak excitation occurred at 27 ms after onset and again at 15 ms following tone offset. Variability of the position of the centroid of excitation during ten recording sessions reached a minimum at 31 ms post onset (σ = 125 µm) and 18 ms post offset (σ = 145 µm), suggesting a fine place/time representation of the stimulus in the cortex. The dynamics of these fast waves also depended on stimulus frequency, likely reflecting the tonotopicity in auditory cortex projected from the cochlea. Peak wave velocities of 0.2 m s−1 were also consistent with those purported across horizontal layers of cat visual cortex. The fine resolution offered by microimaging may be critical for delivering optimal coding strategies used with an auditory prosthesis. Based on the initial results, future studies seek to determine the relevance of these waves to sensory perception and behavior.


Footnote
*  The work was performed at Department of Bioengineering, Arizona State University, ECG 334 MS-9709 Arizona State University, Tempe, AZ 85287-9709, USA.
PACS

87.19.lt Sensory systems: visual, auditory, tactile, taste, and olfaction

43.66.Lj Perceptual effects of sound

87.19.L- Neuroscience

87.19.R- Mechanical and electrical properties of tissues and organs

87.80.-y Biophysical techniques (research methods)

Subjects

Instrumentation and measurement

Medical physics

Biological physics

Dates

Issue 2 (June 2007)

Received 29 November 2006, accepted for publication 9 January 2007

Published 28 February 2007



View by subject




Export








Please login to access our web services, or create an account if you don't yet have one.

You must have cookies enabled in your web browser to be able to login.

Username
Password

Forgotten your password? Get a new one here.