Coding of object location in the vibrissal thalamocortical system.
In whisking rodents, object location is encoded at the receptor level by a combination of motor and sensory related signals. Recoding of the encoded signals can result in various forms of internal representations. Here, we examined the coding schemes occurring at the first forebrain level that receives inputs necessary for generating such internal representations--the thalamocortical network. Single units were recorded in 8 thalamic and cortical stations in artificially whisking anesthetized rats. Neuronal representations of object location generated across these stations and expressed in response latency and magnitude were classified based on graded and binary coding schemes. Both graded and binary coding schemes occurred across the entire thalamocortical network, with a general tendency of graded-to-binary transformation from thalamus to cortex. Overall, 63% of the neurons of the thalamocortical network coded object position in their firing. Thalamocortical responses exhibited a slow dynamics during which the amount of coded information increased across 4-5 whisking cycles and then stabilized. Taken together, the results indicate that the thalamocortical network contains dynamic mechanisms that can converge over time on multiple coding schemes of object location, schemes which essentially transform temporal coding to rate coding and gradual to labeled-line coding.
Current address: Department of Psychology and Neuroscience, Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA.
Chunxiu
C
Yu
Current address: Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Guy
G
Horev
Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel Current address: Department of Psychology and Neuroscience, Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA Current address: Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Naama
N
Rubin
Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel Current address: Department of Psychology and Neuroscience, Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA Current address: Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Dori
D
Derdikman
Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel Current address: Department of Psychology and Neuroscience, Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA Current address: Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Sebastian
S
Haidarliu
Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel Current address: Department of Psychology and Neuroscience, Center for Cognitive Neuroscience, Duke University, Durham, NC 27708, USA Current address: Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
Ehud
E
Ahissar
D000200:Action Potentials; D000818:Animals; D008297:Male; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology; D010812:Physical Stimulation; D020656:Posterior Thalamic Nuclei / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D020651:Ventral Thalamic Nuclei / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology
active sensing; anesthetized rats; artificial whisking; convergence dynamics; neuronal representations; touch