TY - JOUR
T1 - Mechanisms for rapid adaptive control of motion processing in macaque visual cortex
AU - McLelland, Douglas
AU - Baker, Pamela M.
AU - Ahmed, Bashir
AU - Kohn, Adam
AU - Bair, Wyeth
N1 - Publisher Copyright:
© 2015 the authors.
PY - 2015/7/15
Y1 - 2015/7/15
N2 - Akey feature of neural networks is their ability to rapidly adjust their function, including signal gain and temporal dynamics, in response to changes in sensory inputs. These adjustments are thought to be important for optimizing the sensitivity of the system, yet their mechanisms remain poorly understood. We studied adaptive changes in temporal integration in direction-selective cells in macaque primary visual cortex, where specific hypotheses have been proposed to account for rapid adaptation. By independently stimulating direction-specific channels, we found that the control of temporal integration of motion at one direction was independent of motion signals driven at the orthogonal direction. We also found that individual neurons can simultaneously support two different profiles of temporal integration for motion in orthogonal directions. These findings rule out a broad range of adaptive mechanisms as being key to the control of temporal integration, including untuned normalization and nonlinearities of spike generation and somatic adaptation in the recorded direction-selective cells. Such mechanisms are too broadly tuned, or occur too far downstream, to explain the channelspecific and multiplexed temporal integration that we observe in single neurons. Instead, we are compelled to conclude that parallel processing pathways are involved, and we demonstrate one such circuit using a computer model. This solution allows processing in different direction/orientation channels to be separately optimized and is sensible given that, under typical motion conditions (e.g., translation or looming), speed on the retina is a function of the orientation of image components.
AB - Akey feature of neural networks is their ability to rapidly adjust their function, including signal gain and temporal dynamics, in response to changes in sensory inputs. These adjustments are thought to be important for optimizing the sensitivity of the system, yet their mechanisms remain poorly understood. We studied adaptive changes in temporal integration in direction-selective cells in macaque primary visual cortex, where specific hypotheses have been proposed to account for rapid adaptation. By independently stimulating direction-specific channels, we found that the control of temporal integration of motion at one direction was independent of motion signals driven at the orthogonal direction. We also found that individual neurons can simultaneously support two different profiles of temporal integration for motion in orthogonal directions. These findings rule out a broad range of adaptive mechanisms as being key to the control of temporal integration, including untuned normalization and nonlinearities of spike generation and somatic adaptation in the recorded direction-selective cells. Such mechanisms are too broadly tuned, or occur too far downstream, to explain the channelspecific and multiplexed temporal integration that we observe in single neurons. Instead, we are compelled to conclude that parallel processing pathways are involved, and we demonstrate one such circuit using a computer model. This solution allows processing in different direction/orientation channels to be separately optimized and is sensible given that, under typical motion conditions (e.g., translation or looming), speed on the retina is a function of the orientation of image components.
KW - Adaptation
KW - Direction-selective
KW - Temporal integration
UR - http://www.scopus.com/inward/record.url?scp=84937605742&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84937605742&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.1418-11.2015
DO - 10.1523/JNEUROSCI.1418-11.2015
M3 - Article
C2 - 26180202
AN - SCOPUS:84937605742
SN - 0270-6474
VL - 35
SP - 10268
EP - 10280
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 28
ER -