Daily variation and appetitive conditioning-induced plasticity of auditory cortex receptive fields.
Long-term modification of cortical receptive field maps follows learning of sensory discriminations and conditioned associations. In the process of determining whether appetitive - as opposed to aversive - conditioning is effective in causing such plastic changes, it was discovered that multineuron receptive fields, when measured in rats under ketamine-sedation, vary substantially over the course of a week, even in the absence of classical conditioning and electrode movement. Specifically, a simple correlation analysis showed that iso-intensity frequency response curves of multiunit clusters and local field potentials recorded from auditory cortex are nonstationary over 7 days. Nevertheless, significant plastic changes in receptive fields, due to conditioned pairing of a pure tone and electrical stimulation of brain reward centres, are detectable above and beyond these spontaneous daily variations. This finding is based on a novel statistical plasticity criterion which compares receptive fields recorded for three days before and three days after conditioning. Based on a more traditional criterion (i.e. one day before and after conditioning), the prevalence of learning-induced changes caused by appetitive conditioning appears to be comparable to that described in previous studies involving aversive conditioning.
Kisley
M A
MA
Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19103, USA. Michael.Kisley@UCHSC.edu
Gerstein
G L
GL
D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001066:Appetite / Q000502:physiology*; D001303:Auditory Cortex / Q000502:physiology*; D002940:Circadian Rhythm; D003214:Conditioning, Classical / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D007858:Learning / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D010898:Pitch Perception / Q000502:physiology; D051381:Rats; D012201:Reward