TY - JOUR
T1 - Response characteristics of neurons in the medial geniculate body of the little brown bat to simple and temporally-patterned sounds
AU - Llano, D. A.
AU - Feng, A. S.
N1 - Funding Information:
Acknowledgements The authors would like to thank Drs. Alex Galazyuk and David Gooler for their helpful suggestions during the preparation of this manuscript. D.A.L. was supported by the National Institutes of Health Systems and Integrative Physiology Training Grant. Research is supported by grants from the National Institute for Deafness and Other Communicative Disorders of the National Institutes of Health (RO1 DC-01951) and from the Beckman Institute for Advanced Science and Technology.
PY - 1999/4
Y1 - 1999/4
N2 - We examined the auditory response properties of neurons in the medial geniculate body of unanesthetized little brown bats (Myotis lucifugus). The units' selectivities to stimulus frequency, amplitude and duration were not significantly different from those of neurons in the inferior colliculus (Condon et al. 1994), which provides the primary excitatory input to the medial geniculate body, or in the auditory cortex (Condon et al. 1997) which receives primary input from the medial geniculate body. However, in response to trains of unmodulated tone pulses, the upper cutoff frequency for time-locked discharges (64 ± 46.9 pulses per second or pps) and the mean number of spikes per pulse (19.2 ± 12.2 pps). were intermediate to those for the inferior colliculus and auditory cortex. Further, in response to amplitude-modulated pulse trains, medial geniculate body units displayed a degree of response facilitation that was intermediate to that of the inferior colliculus and auditory cortex inferior colliculus: 1.32 ± 0.33: medial geniculate body: 1.75 ± 0.26; auditory cortex: 2.52 = 0.96, P < 0.01). These data suggest that the representation of isolated tone pulses is not significantly altered along the colliculothalamo-cortical axis, but that the fidelity of representation of temporally patterned signals progressively degrades along this axis. The degradation in response fidelity allows the system to better extract the salient feature in complex amplitude-modulated signals.
AB - We examined the auditory response properties of neurons in the medial geniculate body of unanesthetized little brown bats (Myotis lucifugus). The units' selectivities to stimulus frequency, amplitude and duration were not significantly different from those of neurons in the inferior colliculus (Condon et al. 1994), which provides the primary excitatory input to the medial geniculate body, or in the auditory cortex (Condon et al. 1997) which receives primary input from the medial geniculate body. However, in response to trains of unmodulated tone pulses, the upper cutoff frequency for time-locked discharges (64 ± 46.9 pulses per second or pps) and the mean number of spikes per pulse (19.2 ± 12.2 pps). were intermediate to those for the inferior colliculus and auditory cortex. Further, in response to amplitude-modulated pulse trains, medial geniculate body units displayed a degree of response facilitation that was intermediate to that of the inferior colliculus and auditory cortex inferior colliculus: 1.32 ± 0.33: medial geniculate body: 1.75 ± 0.26; auditory cortex: 2.52 = 0.96, P < 0.01). These data suggest that the representation of isolated tone pulses is not significantly altered along the colliculothalamo-cortical axis, but that the fidelity of representation of temporally patterned signals progressively degrades along this axis. The degradation in response fidelity allows the system to better extract the salient feature in complex amplitude-modulated signals.
KW - Amplitude modulation
KW - Echolocation
KW - Temporal processing
KW - Thalamus
UR - http://www.scopus.com/inward/record.url?scp=0033110356&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033110356&partnerID=8YFLogxK
U2 - 10.1007/s003590050336
DO - 10.1007/s003590050336
M3 - Article
C2 - 10377974
AN - SCOPUS:0033110356
SN - 0340-7594
VL - 184
SP - 371
EP - 385
JO - Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
JF - Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
IS - 4
ER -