Primary sensory neurons convey information from the external world to relay circuits within the CNS, but the identity and organization of the neurons that process incoming sensory information remains sketchy. Within the CNS, viral tracing techniques that rely on retrograde transsynaptic transfer provide a powerful tool for delineating circuit organization. Viral tracing of the circuits engaged ...

Target-dependent increases in axon growth and varicosities accompany the formation of functional synapses between Aplysia sensory neurons and specific postsynaptic neurons (L7 and not L11). The enhanced growth is regulated in part by a target-dependent increase in the secretion of sensorin, the sensory neuron neuropeptide. We report here that protein kinase C (PKC) activity is required for syna...

Low threshold Ca2+ currents mediated by T-type channels underlie burst spike activities of relay neurons in the thalamus. We have previously reported that knock-out mice for T-type channels show an enhanced nociceptive response to visceral pain, accompanied by an increase in tonic spikes in the absence of burst spikes in thalamic relay neurons. These results raised a possibility that T-type cha...

It is well established that attention modulates visual processing in extrastriate cortex. However, the underlying neural mechanisms are unknown. A consistent observation is that attention has its greatest impact on neuronal responses when multiple stimuli appear together within a cell's receptive field. One way to explain this is to assume that multiple stimuli activate competing populations of...

A central hypothesis concerning sensory processing is that the neuronal circuits are specifically adapted to represent natural stimuli efficiently. Here we show a novel effect in cortical coding of natural images. Using spike-triggered average or spike-triggered covariance analyses, we first identified the visual features selectively represented by each cortical neuron from its responses to nat...

Crushing nerves, which contain the axons of central sensory neurons, in Aplysia causes the neurons to become hyperexcitable and to sprout new processes. Previous experiments that examined the effects of axonal injury on Aplysia sensory neurons have been performed in the intact animal or in the semi-intact CNS of Aplysia. It therefore has been unclear to what extent the long-term neuronal conseq...

Motivation and attention can have a profound influence on perception, learning and memory. Neuromodulatory systems, especially the noradrenergic (NE) system, co-vary with psychological states to modulate cortical arousal, influence sensory processing and promote synaptic plasticity. There is even some suggestion that the NE system might facilitate functional recovery after brain damage. Post-sy...

Motivation and attention can have a profound influence on perception, learning and memory. Neuromodulatory systems, especially the noradrenergic (NE) system, co-vary with psychological states to modulate cortical arousal, influence sensory processing and promote synaptic plasticity. There is even some suggestion that the NE system might facilitate functional recovery after brain damage. Post-sy...