Receptive field

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

The ON-alpha ganglion cell of the cat retina and its presynaptic cell types

Abstract: Anatomical circuits converging onto the ON-alpha (Y) ganglion cell were studied by computer-assisted reconstruction of substantial portions of 2 alpha cells from electron micrographs of serial sections. The alpha cells in the area centralis were labeled by a Golgi-like retrograde filling with horseradish peroxidase, and certain presynaptic amacrine processes were labeled by uptake of 3H-glycine. About 4400 synapses contacted the alpha cell. Eighty-six percent were from amacrine cells; the rest were from bipolar cells. About one-quarter of the amacrine synapses were specifically labeled by 3H-glycine and probably belong to the A4 amacrine. The bipolar inputs were provided by several types: cone bipolar CBb1 (85%), cone bipolar CBb5 (2%), the rod bipolar (5%), and some unidentified cone bipolars (11%). Contacts from each type occurred in specific strata, with the consequence that they tended to form spots or annulli over the alpha dendritic field. The CBb1 bipolars formed a moderately dense array (8000/mm2), with a nearest-neighbor distance of 8.6 +/- 1.3 microns. Most members of the array (84%) contacted the alpha cell, providing 1-7 synapses (average, 2.7 +/- 1.6). The placement of contacts from an individual CBb1 followed certain rules: they were restricted to a parent branch of the alpha arbor or to 2 daughter branches, but almost never crossed a branch of the alpha arbor. The synaptic territory of an individual CBb1 was not shared with other b1s (or cone bipolars of any sort), although it was shared with amacrine contacts. Rod bipolar cells also formed a very dense array (54,500/mm2) in the alpha dendritic field, but only a few of these (3%) contacted the alpha cell. The concentric receptive field of the CBb1, combined with the spatial organization of its array, is used to predict the CBb1 contribution to the alpha cell receptive field; this contribution resembles the spatial and temporal organization of the alpha receptive field itself.

Expansion of the Cortical Representation of a Specific Skin Field in Primary Somatosensory Cortex by Intracortical Microstimulation

Abstract: Intracortical microstimulation (ICMS) was applied to a single site in the middle cortical layers (III-IV) in the koniocortical somatosensory fields of sodium pentobarbital-anesthetized rats (Sml) and new world monkeys (area 3b). Low-threshold cutaneous receptive fields were defined in the cortical region surrounding the stimulation site prior to and following 2-6 hr of 5 microA ICMS stimulation. ICMS stimulation did not usually affect the receptive field location, size, or responsiveness to tactile stimulation of neurons at the stimulation site. However, the number of cortical neurons surrounding the stimulation site with a receptive field that overlapped with the ICMS-site receptive field increased in all studied animals, resulting in an enlarged cortical representation of a restricted skin region spanning several hundred microns. The mean size of receptive fields changed in some but not all cases. These results provide evidence that the responses of cortical neurons are subject to change by the introduction of locally coincident inputs into a single location, and demonstrate a capacity for representational plasticity in the neocortex in the absence of peripheral stimulation. These experimental observations are consistent with hypotheses that the cerebral cortex comprises radially oriented populations of neurons that share a common input, and that these inputs are shaped by coincident activity (see Edelman, 1978, 1987; Merzenich, 1987; Merzenich et al., 1990; von der Malsburg and Singer, 1988).

Cooling-specific spinothalamic neurons in the monkey

Abstract: 1. Little is known concerning the processing of innocuous thermoreceptive information in the CNS of the monkey. The aim of the present study was to confirm the prediction, based on recent studies in cat and monkey, that there must be a prominent spinothalamic (STT) projection of cooling-specific spinal cord lamina I neurons to the posterior part of the ventral medial nucleus (VMpo) of the monkey thalamus. 2. Experiments were performed on four cynomolgus monkeys anesthetized with pentobarbital sodium. A detailed mapping of somatosensory thalamus was performed in each animal, and VMpo was identified by recordings from clusters of thermoreceptive-specific and nociceptive-specific (NS) neurons. Stimulating electrodes were then implanted in VMpo. Tungsten microelectrodes were used to record the responses of neurons in the superficial dorsal horn of the lumbosacral spinal cord. 3. Many spontaneously active lamina I neurons were found that were inhibited by radiant warming and that responded to innocuous cooling of the hindpaw. These cooling-specific (COLD) neurons were excited by small temperature drops below skin temperature and increased their discharge with decreasing skin temperature. They were not excited by thermally neutral mechanical stimuli applied to the receptive fields. In passing, we also characterized with natural stimulation a few NS neurons reponsive to pinch and/ or noxious heat, multimodal (HPC) neurons responsive to noxious heat, pinch, and cold stimuli, and wide-dynamic-range neurons responsive to both innocuous and noxius cutaneous stimuli that were encountered in lamina I. 4. Twenty lamina I COLD cells were identified as STT neurons by antidromic activation from the contralateral VMpo. The mean conduction latency for these units was 26.1 ms, which corresponds to a mean conduction velocity of approximately 8.0 m/s. They were not antidromically activated from an electrode in the region of the ventral posterior nucleus in the thalamus. In addition, we antidromically activated from VMpo four NS units and three HPC cells. 5. These findings demonstrate for the first time the existence of a prominent direct projection of specific COLD lamina I STT cells to thalamus in the monkey. This is consistent with clinical inferences in humans and with prior results in cats. This result confirms that the dense lamina I STT projection to VMpo demonstrated in anatomic studies includes COLD cells, and it supports the role of VMpo as a thalamic relay nucleus for pain- and temperature-related information.