E.J. Chichilnisky, Postdoctoral Faculty Sponsor
An offset ON-OFF receptive field is created by gap junctions between distinct types of retinal ganglion cells
2021; 24 (1): 105-+
In the vertebrate retina, the location of a neuron's receptive field in visual space closely corresponds to the physical location of synaptic input onto its dendrites, a relationship called the retinotopic map. We report the discovery of a systematic spatial offset between the ON and OFF receptive subfields in F-mini-ON retinal ganglion cells (RGCs). Surprisingly, this property does not come from spatially offset ON and OFF layer dendrites, but instead arises from a network of electrical synapses via gap junctions to RGCs of a different type, the F-mini-OFF. We show that the asymmetric morphology and connectivity of these RGCs can explain their receptive field offset, and we use a multicell model to explore the effects of receptive field offset on the precision of edge-location representation in a population. This RGC network forms a new electrical channel combining the ON and OFF feedforward pathways within the output layer of the retina.
View details for DOI 10.1038/s41593-020-00747-8
View details for Web of Science ID 000724151300003
View details for PubMedID 33230322
View details for PubMedCentralID PMC7769921
Premotor and Motor Cortices Encode Reward
2016; 11 (8): e0160851
Rewards associated with actions are critical for motivation and learning about the consequences of one's actions on the world. The motor cortices are involved in planning and executing movements, but it is unclear whether they encode reward over and above limb kinematics and dynamics. Here, we report a categorical reward signal in dorsal premotor (PMd) and primary motor (M1) neurons that corresponds to an increase in firing rates when a trial was not rewarded regardless of whether or not a reward was expected. We show that this signal is unrelated to error magnitude, reward prediction error, or other task confounds such as reward consumption, return reach plan, or kinematic differences across rewarded and unrewarded trials. The availability of reward information in motor cortex is crucial for theories of reward-based learning and motivational influences on actions.
View details for DOI 10.1371/journal.pone.0160851
View details for Web of Science ID 000382496300004
View details for PubMedID 27564707
View details for PubMedCentralID PMC5001708