Receptive field size for certain neurons in primary somatosensory cortex is determined by GABA-mediated intracortical inhibition

Hicks, T.P.; Dykes, Robert W.

doi:10.1016/0006-8993(83)90533-4

Cited by 148 publications

(68 citation statements)

References 15 publications

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“…This is consistent with pharmacological studies of visual cortex that indicate an important role for y-aminobutyric acid (GABA)-mediated inhibition in shaping the response patterns of cortical neurons to complicated stimulus events (50-52; see also Ref. 19). Inhibitory effects within the cortex are most likely mediated by smooth or sparsely spined stellate cells (see Ref.…”

Section: Cortical Organization and Functionsupporting

confidence: 71%

Temporal and spatial integration in the rat SI vibrissa cortex

Simons¹

1985

Journal of Neurophysiology

298

229

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Glass micropipettes were used to record the activity of 124 single units in the somatosensory vibrissa cortex (SI) of 16 rats in response to combined deflections of contralateral vibrissae. Compact multiangular electromechanical stimulators were used to stimulate individual vibrissal hairs alone or in combinations of two or three adjacent whiskers. Each whisker was stimulated independently to produce controlled temporal and spatial patterns of mechanical stimuli. Following displacement of a vibrissa, unit discharges to subsequent deflections of adjacent whiskers are reduced in a time-dependent fashion. Response suppression is strongest at short interdeflection intervals, i.e., 10-20 ms and decreases progressively during the 50-100 ms following the first deflection. In many cases this period also corresponds with a reduction in ongoing unit discharges. Response suppression was not observed for first-order neurons recorded in the trigeminal ganglion of barbiturate-anesthetized rats. In the cortex, the presence and/or degree of response suppression depends on a number of spatial factors. These include 1) the angular direction(s) in which the individual hairs are moved, 2) the sequence in which two whiskers are deflected, that is, which one is deflected first, 3) the particular combination of whiskers stimulated, and 4) the number (2 or 3) of vibrissae comprising the multiwhisker stimulus. Within a vertical electrode penetration, one particular whisker typically elicits the strongest excitatory and inhibitory effects; other, nearby vibrissae elicit variable (or no) excitation or inhibition. Excitatory and inhibitory subregions of a receptive field could thus be distributed asymmetrically around the maximally effective whisker. In these cases, the receptive fields displayed spatial orientations. Quantitative criteria were used to classify 30 cortical units on the basis of the distribution of inhibitory subregions on either side of the maximally effective whisker. Twenty-one of these cells had receptive fields (RFs) with symmetrical inhibitory side regions. Responses of the other nine units were strongly suppressed by a preceding deflection of a vibrissa on one side but relatively unaffected, or even slightly facilitated, by preceding deflection of the whisker on the other side.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Cortical Organization and Functionsupporting

confidence: 71%

Temporal and spatial integration in the rat SI vibrissa cortex

Simons¹

1985

Journal of Neurophysiology

298

229

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“…It has been suggested that age-related map changes are related to a reduction of intracortical inhibition developing with age, as a reduced level of inhibition would allow excitatory processes to spread. It is undisputed that receptive fields (RFs) are kept small through active inhibition (Hicks and Dykes, 1983). In a study analyzing receptive fields and point-spread functions in somatosensory cortex of aged rats, an enlargement of RF size and of the size of the cortical point-spread function has been described (Spengler et al, 1995;Godde et al, 2002), compatible with a general reduction of cortical inhibition.…”

Section: Introductionmentioning

confidence: 84%

Increased Excitability of Somatosensory Cortex in Aged Humans is Associated with Impaired Tactile Acuity

Lenz¹,

Tegenthoff²,

Kohlhaas³

et al. 2012

J. Neurosci.

101

103

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Aging affects all levels of neural processing, including changes of intracortical inhibition and cortical excitability. Paired-pulse stimulation, the application of two stimuli in close succession, is a useful tool to investigate cortical excitability in humans. The paired-pulse behavior is characterized by the second response being significantly suppressed at short stimulus onset asynchronies. While in rat somatosensory cortex, intracortical inhibition has been demonstrated to decline with increasing age, data from human motor cortex of elderly subjects are controversial and there are no data for the human somatosensory cortex (SI). Moreover, behavioral implications of age-related changes of cortical excitability remain elusive. We therefore assessed SI excitability by combining paired-pulse median nerve stimulation with recording somatosensory evoked potentials in 138 healthy subjects aged 17-86 years. We found that paired-pulse suppression was characterized by substantial interindividual variability, but declined significantly with age, confirming reduced intracortical inhibition in elderly subjects. To link the age-related increase of cortical excitability to perceptual changes, we measured tactile two-point discrimination in a subsample of 26 aged participants who showed either low or high paired-pulse suppression. We found that tactile performance was particularly impaired in subjects showing markedly enhanced cortical excitability. Our data demonstrate that paired-pulse suppression of human SI is significantly reduced in older adults, and that age-related enhancement of cortical excitability correlates with degradation of tactile perception. These findings indicate that cortical excitability constitutes an important mechanism that links age-related neurophysiological changes to behavioral alterations in humans.

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“…GABAergic synapses normally function to restrict cortical activation and thereby contribute to specific input processing (Jones, 1993). Iontophoretic application of the GABA A -receptor antagonists induces a substantial expansion of receptive field size in somatosensory and visual cortical areas (Dykes et al, 1984;Hicks and Dykes, 1983;Kyriazi et al, 1996), as well as a reshaping of motor maps in the motor cortex (Jacobs and Donoghue, 1991). After photothrombotic infarcts, an increase in size of cortical vibrissa representation was also found in the surrounding lesion using metabolic mapping methods , indicating an impairment of specific input processing.…”

Section: Functional Consequences Of Alterations In Gaba a -Receptor Smentioning

confidence: 99%

Widespread and Long-Lasting Alterations in GABA_A-Receptor Subtypes after Focal Cortical Infarcts in Rats: Mediation by NMDA-Dependent Processes

Redecker

Wang

Fritschy

et al. 2002

J Cereb Blood Flow Metab

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Summary: Impairment of inhibitory neurotransmission has been reported to occur in widespread, structurally intact brain regions after focal ischemic stroke. These long-lasting alterations contribute to the functional deficit and influence longterm recovery. Inhibitory neurotransmission is primarily mediated by ␥-aminobutyric acid (GABA) A receptors assembled of five subunits that allow a variety of adaptive changes. In this study, the regional distribution of five major GABA A -receptor subunits (␣1, ␣2, ␣3, ␣5, and ␥2) was analyzed immunohistochemically 1, 7, and 30 days after photochemically induced cortical infarcts. When compared with sham-operated controls, a general and regionally differential reduction in immunostaining was found within the cortex, hippocampus, and thalamus of both hemispheres for almost all subunits. Within ipsilateral and contralateral neocortical areas, a specific pattern of changes with a differential decrease of subunits ␣1, ␣2, ␣5, and ␥2 and a significant upregulation of subunit ␣3 was observed in the contralateral cortex homotopic to the infarct. This dysregulation was most prominent at day 7 and still present at day 30. Interestingly, a single application of the noncompetitive Nmethyl-D-aspartate-receptor antagonist MK-801 during lesion induction completely blocked these bihemispheric alterations. Cortical spreading depressions induced by topical application of KCl do not change GABA A -receptor subunit expression. As alterations in subtype distribution crucially influence inhibitory function, ischemia-induced modifications in GABA A -receptor subtype expression may be of relevance for functional recovery after stroke.

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Receptive field size for certain neurons in primary somatosensory cortex is determined by GABA-mediated intracortical inhibition

Cited by 148 publications

References 15 publications

Temporal and spatial integration in the rat SI vibrissa cortex

Temporal and spatial integration in the rat SI vibrissa cortex

Increased Excitability of Somatosensory Cortex in Aged Humans is Associated with Impaired Tactile Acuity

Widespread and Long-Lasting Alterations in GABA_A-Receptor Subtypes after Focal Cortical Infarcts in Rats: Mediation by NMDA-Dependent Processes

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Receptive field size for certain neurons in primary somatosensory cortex is determined by GABA-mediated intracortical inhibition

Cited by 148 publications

References 15 publications

Temporal and spatial integration in the rat SI vibrissa cortex

Temporal and spatial integration in the rat SI vibrissa cortex

Increased Excitability of Somatosensory Cortex in Aged Humans is Associated with Impaired Tactile Acuity

Widespread and Long-Lasting Alterations in GABAA-Receptor Subtypes after Focal Cortical Infarcts in Rats: Mediation by NMDA-Dependent Processes

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Widespread and Long-Lasting Alterations in GABA_A-Receptor Subtypes after Focal Cortical Infarcts in Rats: Mediation by NMDA-Dependent Processes