Robust Estimation of Spatio-Temporal Receptive Fields of Auditory

2006 ◽  
Author(s):  
Young Lee ◽  
Changwoo Lee ◽  
Poogyeon Park ◽  
Sang Kim
Keyword(s):  
Robust Estimation ◽  
Receptive Fields ◽  
Spatio Temporal

Spatio-Temporal Subthreshold Receptive Fields in the Vibrissa Representation of Rat Primary Somatosensory Cortex

1998 ◽  
Vol 80 (6) ◽  
pp. 2882-2892 ◽  
Author(s):  
Christopher I. Moore ◽  
Sacha B. Nelson
Keyword(s):  
Receptive Field ◽  
Somatosensory Cortex ◽  
Rise Time ◽  
Cortical Plasticity ◽  
Temporal Dynamics ◽  
Receptive Fields ◽  
Excitatory Input ◽  
Primary Somatosensory Cortex ◽  
Spatio Temporal ◽  
Sensory Evoked

Moore, Christopher I. and Sacha B. Nelson. Spatio-temporal subthreshold receptive fields in the vibrissa representation of rat primary somatosensory cortex. J. Neurophysiol. 80: 2882–2892, 1998. Whole cell recordings of synaptic responses evoked by deflection of individual vibrissa were obtained from neurons within adult rat primary somatosensory cortex. To define the spatial and temporal properties of subthreshold receptive fields, the spread, amplitude, latency to onset, rise time to half peak amplitude, and the balance of excitation and inhibition of subthreshold input were quantified. The convergence of information onto single neurons was found to be extensive: inputs were consistently evoked by vibrissa one- and two-away from the vibrissa that evoked the largest response (the “primary vibrissa”). Latency to onset, rise time, and the incidence and strength of inhibitory postsynaptic potentials (IPSPs) varied as a function of position within the receptive field and the strength of evoked excitatory input. Nonprimary vibrissae evoked smaller amplitude subthreshold responses [primary vibrissa, 9.1 ± 0.84 (SE) mV, n = 14; 1-away, 5.1 ± 0.5 mV, n = 38; 2-away, 3.7 ± 0.59 mV, n = 22; 3-away, 1.3 ± 0.70 mV, n = 8] with longer latencies (primary vibrissa, 10.8 ± 0.80 ms; 1-away, 15.0 ± 1.2 ms; 2-away, 15.7 ± 2.0 ms). Rise times were significantly faster for inputs that could evoke action potential responses (suprathreshold, 4.1 ± 1.3 ms, n = 8; subthreshold, 12.4 ± 1.5 ms, n = 61). In a subset of cells, sensory evoked IPSPs were examined by deflecting vibrissa during injection of hyperpolarizing and depolarizing current. The strongest IPSPs were evoked by the primary vibrissa ( n = 5/5), but smaller IPSPs also were evoked by nonprimary vibrissae ( n = 8/13). Inhibition peaked by 10–20 ms after the onset of the fastest excitatory input to the cortex. This pattern of inhibitory activity led to a functional reversal of the center of the receptive field and to suppression of later-arriving and slower-rising nonprimary inputs. Together, these data demonstrate that subthreshold receptive fields are on average large, and the spatio-temporal dynamics of these receptive fields vary as a function of position within the receptive field and strength of excitatory input. These findings constrain models of suprathreshold receptive field generation, multivibrissa interactions, and cortical plasticity.

scholarly journals Energy saving in vision at the first synapse: The ON and OFF pathways measure temporal differences

2017 ◽  
Author(s):  
Bart M. ter Haar Romeny
Keyword(s):  
Visual System ◽  
Receptive Fields ◽  
Dendritic Tree ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Inner Plexiform Layer ◽  
Surveillance Camera ◽  
Starburst Amacrine Cells ◽  
Spatio Temporal ◽  
On And Off Pathways

AbstractThe inner plexiform layer (IPL) of mammalian retina has a precise bisublaminar organization in an inner on- and an outer off-layer, innervated by spatially segregated on- and off-cone bipolar cell inputs. Also, the processes of starburst amacrine cells are segregated into on and off sublaminae of the IPL. Distances between overlapping on-off pair retinal ganglion cell dendritic tree centers are markedly smaller than between on-on or off-off centers, indicating simultaneously sampling the same space. Despite dekades of research, no good model exists for the role of the on- and off pathways. Here I propose that the on- and off pairs are temporally subtracted, with one channel delayed in time, likely in a higher cortical center. The on- and off receptive fields give at every retinal location an I+ and I-signal, where I is intensity, velocity, color. Subsequent frame subtraction is a basis function of every surveillance camera for vision, and in MPEG video/sound compression. The model explains the many phenomena observed when the retinal image is stabilized. The separation of layers in the LGN fits with the notion of a time delay at higher cortical level. The directionalty observed in micro-saccades is typically perpendicular to the main edges in the scene. Precise measurement of spatio-temporal receptive field kernels shows that time is processed in the visual system as a real-time process, i.e. with a logarithmic time axis. As only contours and textures are transmitted, it is a very effective design strategy of the visual system to conserve energy, in a brain that typically uses 25 Watt and very low neuron firing frequencies. The higher visual centers perform the fill-in (inpainting) with such efficiency, that the subtraction always goes unnoticed.

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