Receptive field

About: Receptive field is a research topic. Over the lifetime, 8537 publications have been published within this topic receiving 596428 citations.

Effects of cholinergic drugs on receptive field properties of rabbit retinal ganglion cells.

Abstract: 1. Retinal ganglion cells were recorded extracellularly from the rabbit's eye in situ to study the effects of cholinergic drugs on receptive field properties. Physostigmine, an acetylcholinesterase inhibitor, and nicotine increased the spontaneous activity of nearly all retinal ganglion cell types. The effectiveness of physostigmine was roughly correlated with the neurone's inherent level of spontaneous activity. Brisk cells, having high rates of spontaneous firing, showed large increases in their maintained discharge, whereas sluggish cells, with few or no spontaneous spikes, showed small and sometimes transient increases in spontaneous activity during physostigmine. 2. The sensitivity of ganglion cells to spots of optimal size and position did not change substantially during the infusion of physostigmine. However, the responsiveness to light (number of spikes per stimulus above the spontaneous level) increased. This effect occurred with sluggish and more complex cells, rarely with brisk cells. 3. Another effect of physostigmine on sluggish and more complex cells was to make these cells `on—off'. The additional response to the inappropriate change in contrast had a long latency and lacked an initial transient burst. 4. Complex receptive field properties such as orientation sensitivity, radial grating inhibition, speed tuning and size specificity were also examined. These inhibitory properties were still present during infusion of physostigmine and, in most cases, the trigger feature of each cell type remained. 5. These results are consistent with pharmacological results on ACh release from the retina. There appear to be two types of release of ACh, having their most powerful influences on separate classes of cells. One release (transient), occurs at light onset and offset and acts primarily on sluggish and more complex ganglion cells; the other release (tonic) is not light-modulated and acts primarily on brisk cells. A wiring diagram for the ACh cells is suggested.

Receptive field structure of neurons in monkey primary visual cortex revealed by stimulation with natural image sequences.

Abstract: Probing the visual system with the ensemble of signals that occur in the natural environment may reveal aspects of processing that are not evident in the neural responses to artificial stimulus sets, such as conventional bars and sinusoidal gratings. However, unsolved is the question of how to use complex natural stimulation, many aspects of which the experimenter cannot completely specify, to study neural processing. Here a method is presented to investigate the structure of a neuron's receptive field based on its response to movie clips and other stimulus ensembles. As a particular case, the technique provides an estimate of the conventional first-order receptive field of a neuron, similar to what can be obtained with other reverse-correlation schemes. This is demonstrated experimentally and with computer simulations. Our analysis also revealed that the receptive fields of both simple and complex cells had regions where image boundaries, independent of their contrast sign, would enhance or suppress the cell's response. In some cases, these signals were tuned for the orientation of the boundary. This demonstrates for the first time that it might be feasible to investigate the receptive field structure of visual neurons from their responses to natural image sequences.

Stimulus-Dependent Auditory Tuning Results in Synchronous Population Coding of Vocalizations in the Songbird Midbrain

Abstract: Physiological studies in vocal animals such as songbirds indicate that vocalizations drive auditory neurons particularly well. But the neural mechanisms whereby vocalizations are encoded differently from other sounds in the auditory system are unknown. We used spectrotemporal receptive fields (STRFs) to study the neural encoding of song versus the encoding of a generic sound, modulation-limited noise, by single neurons and the neuronal population in the zebra finch auditory midbrain. The noise was designed to match song in frequency, spectrotemporal modulation boundaries, and power. STRF calculations were balanced between the two stimulus types by forcing a common stimulus subspace. We found that 91% of midbrain neurons showed significant differences in spectral and temporal tuning properties when birds heard song and when birds heard modulation-limited noise. During the processing of noise, spectrotemporal tuning was highly variable across cells. During song processing, the tuning of individual cells became more similar; frequency tuning bandwidth increased, best temporal modulation frequency increased, and spike timing became more precise. The outcome was a population response to song that encoded rapidly changing sounds with power and precision, resulting in a faithful neural representation of the temporal pattern of a song. Modeling responses to song using the tuning to modulation-limited noise showed that the population response would not encode song as precisely or robustly. We conclude that stimulus-dependent changes in auditory tuning during song processing facilitate the high-fidelity encoding of the temporal pattern of a song.

Adaptive Changes in Cortical Receptive Fields Induced by Attention to Complex Sounds

Abstract: Receptive fields in primary auditory cortex (A1) can be rapidly and adaptively reshaped to enhance responses to salient frequency cues when using single tones as targets. To explore receptive field changes to more complex spectral patterns, we trained ferrets to detect variable, multitone targets in the context of background, rippled noise. Recordings from A1 of behaving ferrets showed a consistent pattern of plasticity, at both the single-neuron level and the population level, with enhancement for each component tone frequency and suppression for intertone frequencies. Plasticity was strongest near neuronal best frequency, rapid in onset, and slow to fade. Although attention may trigger cortical plasticity, the receptive field changes persisted after the behavioral task was completed. The observed comb filter plasticity is an example of an adaptive contrast matched filter, which may generally improve discriminability between foreground and background sounds and, we conjecture, may predict A1 cortical plasticity for any complex spectral target.

Neuronal Responses in Area 7a to Multiple-stimulus Displays: I. Neurons Encode the Location of the Salient Stimulus

Abstract: The primate posterior parietal cortex (PPC) plays an important role in representing and recalling spatial relationships and in the ability to orient visual attention. This is evidenced by the parietal activation observed in brain imaging experiments performed during visuo- spatial tasks, and by the contralateral neglect syndrome that often accompanies parietal lesions. Individual neurons in monkey parietal cortex respond vigorously to the appearance of single, behaviorally relevant stimuli, but little is known about how they respond to more complex visual displays. The current experiments addressed this issue by recording activity from single neurons in area 7a of the PPC in monkeys performing a spatial version of a match-to-sample task. The task required them to locate salient stimuli in multiple-stimulus displays and release a lever after a subsequent stimulus appeared at the same location. Neurons responded preferentially to the appearance of salient stimuli inside their receptive fields. The presence of multiple stimuli did not affect appreciably the spatial tuning of responses in the majority of neurons or the population code for the location of the salient stimulus. Responses to salient stimuli could be distinguished from background stimuli approximately 100 ms after the onset of the cue. These results suggest that area 7a neurons represent the location of the stimulus attracting the animal's attention and can provide the spatial information required for directing attention to a salient stimulus in a complex scene.