Receptive field

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

Architecture of rod and cone circuits to the on-beta ganglion cell

Abstract: Photoreceptors connect to the on-beta ganglion cell through parallel circuits involving rod bipolar (RB) and cone bipolar (CB) neurons. We estimated for a small patch in the area centralis of one retina the 3- dimensional architecture of both circuits. This was accomplished by reconstructing neurons and synapses from electron micrographs of 189 serial sections. There were (per mm2) 27,000 cones, 450,000 rods, 6500 CBb1, 30,300 RB, 4100 All amacrines, and 2000 on-beta ganglion cells. The tangential spread of processes was determined for each cell type, and, with the densities, this allowed us to calculate the potential convergence and divergence of each array upon the next. The actual numbers of cells converging and diverging were estimated from serial sections, as were the approximate numbers of chemical synapses involved. The cone bipolar circuit showed narrow convergence and divergence: 16 cones----4 CBb1----1 on-beta 1 cone----1 CBb1----1.2 on- beta This circuit is thought to contribute significantly to the on-beta cell9s photopic receptive field because the CBb1 has a center-surround receptive field whose center diameter is greater than the spacing between adjacent CBb1s. Consequently, the receptive fields of the CBb1s converging on a beta cell are probably largely concentric and thus mutually reinforcing in their contributions to the on-beta. The rod bipolar circuit showed a wider convergence and divergence: 1500 rods---- 100 RB----5 AII----4 CBb1----1 on-beta 1 rod----2 RB----5 AII----8 CBb1- ---2----2 on-beta The 1500 rods converging via this circuit account for the spatial extent of the beta cell9s dark-adapted receptive field. This convergence also accounts for the ganglion cell9s maintained discharge, which is thought to arise from about 6 quantal “dark events” per second. This many dark events would appear in the ganglion cell if each rod in the circuit contributed 0.004 dark events per second, and this is close to what has been measured in monkey rods (Baylor et al., 1984). Divergence in this circuit serves to expand the number of copies of the quantal signal (1 rod----8 CBb1) and so to engage large numbers of chemical synapses that provide amplification. Reconvergence at the last stage (8 CBb1----2 on-beta) may reduce (by signal averaging) the synaptic noise that would otherwise accumulate along the pathway.

Long-term retention of learning-induced receptive-field plasticity in the auditory cortex.

Abstract: Brief learning experience (classical conditioning) induces frequency-specific receptive-field (RF) plasticity in the auditory cortex, characterized as increased response to the frequency of the conditioned stimulus and decreased responses to most other frequencies, including the pretraining best frequency. This experiment asked (i) whether learning-induced RF plasticity, established in the waking state, can be expressed under general anesthesia and if so (ii) whether it exhibits long-term retention. Pure-tone-frequency RFs were obtained from adult guinea pigs under general anesthesia (sodium pentobarbital or ketamine) before and repeatedly after (1 hr-8 weeks) a 20- to 30-trial session of pairing a non-best-frequency tone with mild footshock. Conditioned-stimulus-specific RF plasticity was expressed under both types of anesthesia and included shifts of the pretraining best frequency toward or even to the frequency of the conditioned stimulus. Moreover, this RF plasticity exhibits long-term retention, being evident 1-8 weeks after training. This satisfies a criterion for the long-term storage of information in the auditory cortex.

Single-unit analysis of the human ventral thalamic nuclear group: somatosensory responses.

Abstract: 1. We have studied the functional and somatotopic properties of 531 single mechanoreceptive thalamic neurons in humans undergoing stereotactic surgery for the control of movement disorders and pain. The majority of these somatosensory cells had small receptive fields (RFs) and were activated in a reproducible manner by mechanical stimuli applied to the skin or deep tissues. These neurons, which we termed "lemniscal," could be further classified into those responding to stimulation of cutaneous (76% of lemniscal sensory cells) or deep (24%) structures. 2. The incidence of neurons having cutaneous or mucosal RFs in the perioral region, thumb, and fingers (66%) was much higher than that of neurons having RFs elsewhere on the body. Most of the deep cells were activated by movements of and/or mechanical stimuli delivered to muscles or tendons controlling the elbow, wrist, and fingers. 3. Sequences of cells spanning several millimeters in the parasagittal plane often exhibited overlapping RFs. However, RFs changed markedly for cells separated by the same distances in the mediolateral direction. This suggests that the cutaneous somatotopic representation of each region of the body is organized into relatively thin sheets of cells oriented in the parasagittal plane. 4. By comparing neuronal RFs in different parasagittal planes in thalamus of individual patients we have identified a mediolateral representation of body surface following the sequence from: intraoral structures, face, thumb through fifth finger to palm, with forearm and leg laterally. 5. Along many trajectories in the parasagittal plane the sequence of cells with overlapping RFs was interrupted by another sequence of cells with RFs corresponding to a different body region. The RFs of the intervening sequence characteristically represented body regions known to be located more medially in thalamus (see 3 above). These findings could be explained if the lamellae postulated above were laterally convex. 6. Cells responding to deep stimulation (deep cells) could be further classified into those responding to joint movement (63%), deep pressure (15%), or both (22%). Deep cells were found usually at the anterior-dorsal border and sometimes at the posterior border of the region containing cells responding to cutaneous stimuli. Although there was some overlap in the RFs, deep cells representing wrist were found medial to those representing elbow, and both of these were found medial to cells representing leg.(ABSTRACT TRUNCATED AT 400 WORDS)