Activity In Primary Somatosensory Cortex Research Articles

Widespread spatial integration in primary somatosensory cortex

Tactile discrimination depends on integration of information from the discrete receptive fields (RFs) of peripheral sensory afferents. Because this information is processed over a hierarchy of subcortical nuclei and cortical areas, the integration likely occurs at multiple levels. The current study presents results indicating that neurons across most of the extent of the hand representation in monkey primary somatosensory cortex (area 3b) interact, even when these neurons have separate RFs. We obtained simultaneous recordings by using a 100-electrode array implanted in the hand representation of primary somatosensory cortex of two anesthetized owl monkeys. During a series of 0.5-s skin indentations with single or dual probes, the distance between electrodes from which neurons with synchronized spike times were recorded exceeded 2 mm. The results provide evidence that stimuli on different parts of the hand influence the degree of synchronous firing among a large population of neurons. Because spike synchrony potentiates the activation of commonly targeted neurons, synchronous neural activity in primary somatosensory cortex can contribute to discrimination of complex tactile stimuli.

Differences in Low Back Pain Behavior Are Reflected in the Cerebral Response to Tactile Stimulation of the Lower Back

Two groups of patients with chronic low back pain (cLBP) were scanned with functional magnetic resonance imaging during stimulation of the lower back; those showing 4 or 5 positive Waddell signs (WS-H) and those showing 1 or none (WS-L) as an index of pain-related illness behavior. We hypothesized that patients showing good versus poor adjustment to cLBP mobilize cortical affective-cognitive functions differently in response to sensory stimulation and show increased reorganization of somatosensory cortex corresponding to the back. Some patients with cLBP go on to develop significant disability while the majority do not, and physical disease or psychosocial factors alone do not account for the difference. Neuroimaging studies have suggested abnormalities in cortical pain modulation systems can lead to variable pain and behavioral responses, which may account for these differences. METHODS.: Fifteen WS-L and 13 WS-H patients were scanned with functional magnetic resonance imaging while receiving intense tactile stimulation to the lower back. Questionnaire measures of psychosocial function were also collected. There were no significant differences in cLBP duration or lumbar stimulation tolerance threshold between the 2 groups. Significantly more activation was seen in the WS-L versus WS-H group in regions previously associated with normal affective-cognitive processing of sensory input including posterior cingulate and parietal cortices; the magnitude of this activation negatively correlated with catastrophizing scores. WS-H patients showed a modest medial shift in primary somatosensory cortex activation relative to the WS-L group. Successful adjustment to cLBP is associated with a patient's ability to effectively engage a sensory modulation system. In patients in whom such activation does not occur, subjective lack of control maypredispose to altered affective and behavioral responses with poor adjustment to pain. Pain experience may be furthermodified by reorganization of somatosensory cortex, contributing to maintenance of the chronic pain state.

The perception of pain in others suppresses somatosensory oscillations: A magnetoencephalography study

Accumulating evidence demonstrates that similar neural circuits are activated during the first-hand experience of pain and the observation of pain in others. However, most functional MRI studies did not detect signal change in the primary somatosensory cortex during pain empathy. To test if the perception of pain in others involves the primary somatosensory cortex, neuromagnetic oscillatory activity was recorded from the primary somatosensory cortex in 16 participants while they observed static pictures depicting body parts in painful and non-painful situations. The left median nerve was stimulated at the wrist, and the poststimulus rebounds of the ~10-Hz somatosensory cortical oscillations were quantified. Compared to the baseline condition, the level of the ~10-Hz oscillations was suppressed during both of the observational situations, indicating the activation of the primary somatosensory cortex. Importantly, watching painful compared to non-painful situations suppressed somatosensory oscillations to a significant stronger degree. In addition, the suppression caused by perceiving others in the painful relative to the non-painful situations correlated with the perspective taking subscale of the interpersonal reaction index. These results, consistent with the mirror-neuron system, demonstrate that the perception of pain in others modulates neural activity in primary somatosensory cortex and supports the idea that the perception of pain in others elicits subtle somatosensory activity that may be difficult to detect by fMRI techniques.

High-Resolution Maps of Real and Illusory Tactile Activation in Primary Somatosensory Cortex in Individual Monkeys with Functional Magnetic Resonance Imaging and Optical Imaging

Although blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been widely used to explore human brain function, questions remain regarding the ultimate spatial resolution of positive BOLD fMRI, and indeed the extent to which functional maps revealed by positive BOLD correlate spatially with maps obtained with other high-spatial-resolution mapping techniques commonly used in animals, such as optical imaging of intrinsic signal (OIS) and single-unit electrophysiology. Here, we demonstrate that the positive BOLD signal at 9.4T can reveal the fine topography of individual fingerpads in single-condition activation maps in nonhuman primates. These digit maps are similar to maps obtained from the same animal using intrinsic optical imaging. Furthermore, BOLD fMRI reliably resolved submillimeter spatial shifts in activation in area 3b previously identified with OIS (Chen et al., 2003) as neural correlates of the "funneling illusion." These data demonstrate that at high field, high-spatial-resolution topographic maps can be achieved using the positive BOLD signal, weakening previous notions regarding the spatial specificity of the positive BOLD signal.

Cortical Processing of Noxious Somatosensory Stimuli in the Persistent Vegetative State

The persistent vegetative state (PVS) is a devastating medical condition characterized by preserved wakefulness contrasting with absent voluntary interaction with the environment. We used positron emission tomography to assess the central processing of noxious somatosensory stimuli in the PVS. Changes in regional cerebral blood flow were measured during high-intensity electrical stimulation of the median nerve compared with rest in 15 nonsedated patients and in 15 healthy controls. Evoked potentials were recorded simultaneously. The stimuli were experienced as highly unpleasant to painful in controls. Brain glucose metabolism was also studied with [ 18F]fluorodeoxyglucose in resting conditions. In PVS patients, overall cerebral metabolism was 40% of normal values. Nevertheless, noxious somatosensory stimulation-activated midbrain, contralateral thalamus, and primary somatosensory cortex in each and every PVS patient, even in the absence of detectable cortical evoked potentials. Secondary somatosensory, bilateral insular, posterior parietal, and anterior cingulate cortices did not show activation in any patient. Moreover, in PVS patients, the activated primary somatosensory cortex was functionally disconnected from secondary somatosensory, bilateral posterior parietal, premotor, polysensory superior temporal, and prefrontal cortices. In conclusion, somatosensory stimulation of PVS patients, at intensities that elicited pain in controls, resulted in increased neuronal activity in primary somatosensory cortex, even if resting brain metabolism was severely impaired. However, this activation of primary cortex seems to be isolated and dissociated from higher-order associative cortices.

Cortical Processing of Noxious Somatosensory Stimuli in the Persistent Vegetative State

The persistent vegetative state (PVS) is a devastating medical condition characterized by preserved wakefulness contrasting with absent voluntary interaction with the environment. We used positron emission tomography to assess the central processing of noxious somatosensory stimuli in the PVS. Changes in regional cerebral blood flow were measured during high-intensity electrical stimulation of the median nerve compared with rest in 15 nonsedated patients and in 15 healthy controls. Evoked potentials were recorded simultaneously. The stimuli were experienced as highly unpleasant to painful in controls. Brain glucose metabolism was also studied with [ 18 F]fluorodeoxyglucose in resting conditions. In PVS patients, overall cerebral metabolism was 40% of normal values. Nevertheless, noxious somatosensory stimulation-activated midbrain, contralateral thalamus, and primary somatosensory cortex in each and every PVS patient, even in the absence of detectable cortical evoked potentials. Secondary somatosensory, bilateral insular, posterior parietal, and anterior cingulate cortices did not show activation in any patient. Moreover, in PVS patients, the activated primary somatosensory cortex was functionally disconnected from secondary somatosensory, bilateral posterior parietal, premotor, polysensory superior temporal, and prefrontal cortices. In conclusion, somatosensory stimulation of PVS patients, at intensities that elicited pain in controls, resulted in increased neuronal activity in primary somatosensory cortex, even if resting brain metabolism was severely impaired. However, this activation of primary cortex seems to be isolated and dissociated from higher-order associative cortices.

Early activation of the primary somatosensory cortex without conscious awareness of somatosensory stimuli in tumor patients

The primary sensory cortex has usually been regarded as a necessary step in the information processing stream leading to conscious awareness. Recently, it has been proposed that that higher order associative areas rather than the primary sensory areas are the neural basis of conscious perception. In two patients with tumors near the central region we recorded magnetic somatosensory evoked fields. Magnetic source imaging revealed early (40 ms) neural activation in primary somatosensory cortex and absence of later (>60 ms) neural activation in the primary and associative areas in these patients. None of the patients showed conscious awareness of somatosensory stimuli applied to the corresponding body site although the first component of the evoked field was within normal limits. The time course of the magnetic responses and additional evidence on intensity ratings of somatosensory stimuli suggest that early activity in the primary somatosensory cortex is not sufficient for conscious experience to emerge.

Effects of stimulus presentation rate on the activity of primary somatosensory cortex: a functional magnetic resonance imaging study in humans

To investigate the effect of stimulus presentation rate on the activity of primary somatosensory cortex, we performed echo-planar functional magnetic resonance imaging using a 1.5-tesla magnetic resonance system. Eight right-handed normal volunteers underwent functional magnetic resonance imaging during somatosensory stimulation with a 0.2 ms electrical square wave to the left index finger at 1, 4, 8, 16, and 32 Hz at constant intensity. Activated areas were located mainly around ‘the hand area’ of the right postcentral gyrus. Between 4 and 16 Hz, almost all subjects showed significant activation, but at 1 Hz and 32 Hz, five of eight subjects showed no activation. The average number of activated pixels in this area between 4 and 16 Hz were significantly greater than those at 1 Hz and 32 Hz, and the average percent signal increase had its activation peak at 8 Hz. Our results suggest that the existence of the optimal stimulation rate range may be a common phenomenon to a variety of sensory modalities. The electrical somatosensory stimulation rates from 4 Hz to 16 Hz are advisable to investigate the activation of the primary somatosensory cortex in human subjects.

Primary somatosensory cortex activation is not altered in patients with ventroposterior thalamic lesions: a PET study.

We know remarkably little about the mechanisms underlying cortical activation. Such mechanisms might be better understood by studying the effect of well-localized lesions on the cortical activations in simple paradigms. We used H(2)(15)O and positron emission tomography to measure regional cerebral blood flow (rCBF) at rest and during hand vibration in 7 patients with unilateral thalamic lesion involving the ventroposterior (VP) somatosensory thalamic relay nuclei. We compared the results with those obtained in 6 patients with thalamic lesions sparing the VP nuclei and 6 healthy controls. The patients with VP lesions had a selective hypoperfusion at rest in the ipsilesional primary sensorimotor cortex (SM1). This hypoperfusion was significantly correlated with the degree of contralateral somatosensory deficit. This abnormality may reflect the deafferentation of SM1 from its somatosensory thalamic input. Despite this deafferentation, the ipsilesional SM1 was normally activated by the vibration of the hypoesthetic hand. The fact that a lesion of the somatosensory thalamic relay nuclei alters the rCBF at rest in SM1 but not its activation by hand vibration indicates that the mechanism of cortical activation is complex, even in the case of simple sensory stimulation. In addition, a dissociation may occur between obvious neurological deficits and apparently normal activation patterns, which suggests that activation studies should be interpreted cautiously in patients with focal brain lesions.

Cortically induced thalamic plasticity in the primate somatosensory system.

The influence of cortical feedback on receptive field organization in the thalamus was assessed in the primate somatosensory system. Chronic and acute suppression of neuronal activity in primary somatosensory cortex resulted in a striking enlargement of receptive fields in the ventroposterior thalamus. This finding demonstrates a dramatic 'top-down' influence of cortex on receptive field size in the somatosensory thalamus. In addition, this result has important implications for studies of adult neuronal plasticity because it indicates that changes in 'higher-order' areas of the brain can trigger extensive changes in the receptive field characteristics of neurons located earlier in the processing pathway.

Pain affect encoded in human anterior cingulate but not somatosensory cortex.

Recent evidence demonstrating multiple regions of human cerebral cortex activated by pain has prompted speculation about their individual contributions to this complex experience. To differentiate cortical areas involved in pain affect, hypnotic suggestions were used to alter selectively the unpleasantness of noxious stimuli, without changing the perceived intensity. Positron emission tomography revealed significant changes in pain-evoked activity within anterior cingulate cortex, consistent with the encoding of perceived unpleasantness, whereas primary somatosensory cortex activation was unaltered. These findings provide direct experimental evidence in humans linking frontal-lobe limbic activity with pain affect, as originally suggested by early clinical lesion studies.

Multiple Representations of Pain in Human Cerebral Cortex

The representation of pain in the cerebral cortex is less well understood than that of any other sensory system. However, with the use of magnetic resonance imaging and positron emission tomography in humans, it has now been demonstrated that painful heat causes significant activation of the contralateral anterior cingulate, secondary somatosensory, and primary somatosensory cortices. This contrasts with the predominant activation of primary somatosensory cortex caused by vibrotactile stimuli in similar experiments. Furthermore, the unilateral cingulate activation indicates that this forebrain area, thought to regulate emotions, contains an unexpectedly specific representation of pain.

Changes in premovement activity in primary somatosensory cortex differ when monkeys make hand movements in response to visual vs vibratory cues

Rhesus monkeys were taught to make identical wrist flexion and extension movements in response to either a visual cue or to vibratory cues. Changes in firing rates that were not stimulus-associated but preceded the movements were measured for each primary somatosensory cortical neuron recorded under the two stimulus cued conditions. The onset of the premovement activity changes and the magnitude of these changes differed when visually cued trials were compared with vibratory cued trials that resulted in the same behavioral response. In general, the magnitudes of premovement activity changes were less and the onset of these changes occurred earlier for vibratory cued trials than for the corresponding trials triggered by the visual stimulus. These findings support the hypothesis that centrally generated modulatory influences arriving at primary somatosensory cortical neurons prior to movement onset may differ, depending upon the modality of the stimulus which signals that a movement may be initiated.

Neuronal mechanisms underlying direction sensitivity of somatosensory cortical neurons in awake monkeys.

Neuronal mechanisms underlying direction sensitivity of somatosensory cortical neurons in awake monkeys.E P Gardner, and R M CostanzoE P Gardner, and R M CostanzoPublished Online:01 May 1980https://doi.org/10.1152/jn.1980.43.5.1342MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByNeural Basis of Touch and Proprioception in Primate Cortex14 September 2018The Neural Basis of Haptic Perception23 March 2018Neuronal activity in somatosensory cortex related to tactile explorationPascal Fortier-Poisson and Allan M. Smith12 January 2016 | Journal of Neurophysiology, Vol. 115, No. 1The neural basis of tactile motion perceptionYu-Cheng Pei, and Sliman J. Bensmaia15 December 2014 | Journal of Neurophysiology, Vol. 112, No. 12Reversible deactivation of higher-order posterior parietal areas. I. Alterations of receptive field characteristics in early stages of neocortical processingDylan F. Cooke*, Adam B. Goldring*, Mary K. L. Baldwin, Gregg H. Recanzone, Arnold Chen, Tingrui Pan, Scott I. Simon, and Leah Krubitzer15 November 2014 | Journal of Neurophysiology, Vol. 112, No. 10Dipole Source Analyses of Early Median Nerve SEP Components Obtained From Subdural Grid RecordingsUlf Baumgärtner, Hagen Vogel, Shinji Ohara, Rolf-Detlef Treede, and Fred A. Lenz1 December 2010 | Journal of Neurophysiology, Vol. 104, No. 6Cutaneous Afferents From the Monkeys Fingers: Responses to Tangential and Normal ForcesH. E. Wheat, L. M. Salo, and A. W. Goodwin1 February 2010 | Journal of Neurophysiology, Vol. 103, No. 2Afferent Input, Efference Copy, Signal Noise, and Biases in Perception of Joint Angle During Active Versus Passive Elbow MovementsV. Gritsenko, N. I. Krouchev, and J. F. Kalaska1 September 2007 | Journal of Neurophysiology, Vol. 98, No. 3Neural Mechanisms Underlying Selectivity for the Rate and Direction of Frequency-Modulated Sweeps in the Auditory Cortex of the Pallid BatKhaleel A. Razak, and Zoltan M. Fuzessery1 September 2006 | Journal of Neurophysiology, Vol. 96, No. 3Receptive field structure in cortical area 3b of the alert monkeyBehavioural Brain Research, Vol. 135, No. 1-2Tactile motion activates the human middle temporal/V5 (MT/V5) complex27 September 2002 | European Journal of Neuroscience, Vol. 16, No. 5Tactile Discrimination of Gaps by Slowly Adapting Afferents: Effects of Population Parameters and Anisotropy in the FingerpadHeather E. Wheat, and Antony W. Goodwin1 September 2000 | Journal of Neurophysiology, Vol. 84, No. 3Somatosensory areas in man activated by moving stimuliNeuroReport, Vol. 11, No. 1Topography of excitatory and inhibitory muscle responses evoked by transcranial magnetic stimulation in the human motor cortexNeuroscience Letters, Vol. 154, No. 1-2Effects of traverse length on human perioral directional sensitivityJournal of the Neurological Sciences, Vol. 93, No. 2-3Changes in premovement activity in primary somatosensory cortex differ when monkeys make hand movements in response to visual vs vibratory cuesBrain Research, Vol. 484, No. 1-2Set related and premovement related activity of primate primary somatosensory cortical neurons depends upon stimulus modality and subsequent movementBrain Research Bulletin, Vol. 21, No. 3What the robot's hand should tell the robot's brain: feature detection in a biological neural networkCharacteristics of periodontal mechanosensitive neurons in the first somatosensory cortex of the catBrain Research, Vol. 409, No. 1Somatosensory detection of microgeometry, macrogeometry and kinesthesia in manBrain Research Reviews, Vol. 12, No. 1Somatosensory detection of microgeometry, macrogeometry and kinesthesia after localized lesions of the cerebral hemispheres in manBrain Research Reviews, Vol. 12, No. 1The response of single guard and down hair mechanoreceptors to moving air-jet stimulationBrain Research, Vol. 346, No. 2Excitation of dorsal column nucleus neurons by air-jet moving across the skinBrain Research, Vol. 346, No. 2Somatosensory cortex in macaque monkeys: laminar differences in receptive field size in areas 3b and 1Brain Research, Vol. 342, No. 2Mechanoreceptive submodality channel interactions: single unit analysis of afferent inhibition in the primary somatosensory cortex of the catBrain Research, Vol. 327, No. 1-2Parallel processing of somatosensory information: A theoryBrain Research Reviews, Vol. 6, No. 1AgraphesthesiaJournal of the Neurological Sciences, Vol. 53, No. 3Properties of kinesthetic neurons in somatosensory cortex of awake monkeysBrain Research, Vol. 214, No. 2Multiple-joint neurons in somatosensory cortex of awake monkeysBrain Research, Vol. 214, No. 2 More from this issue > Volume 43Issue 5May 1980Pages 1342-54 https://doi.org/10.1152/jn.1980.43.5.1342PubMed6768850History Published online 1 May 1980 Published in print 1 May 1980 Metrics

Influence of attentive behavior on neuronal responses to vibration in primary somatosensory cortex of the monkey.

Influence of attentive behavior on neuronal responses to vibration in primary somatosensory cortex of the monkey.

Responses of identified cells in postcentral cortex of awake monkeys during comparable active and passive joint movements.

Responses of identified cells in postcentral cortex of awake monkeys during comparable active and passive joint movements.

Spatial integration of multiple-point stimuli in primary somatosensory cortical receptive fields of alert monkeys.

Spatial integration of multiple-point stimuli in primary somatosensory cortical receptive fields of alert monkeys.

Temporal integration of multiple-point stimuli in primary somatosensory cortical receptive fields of alert monkeys

Temporal integration of multiple-point stimuli in primary somatosensory cortical receptive fields of alert monkeys

Unit activity of primary somatosensory cortex during primary responses

1. In three series of experiments on cats responses of 490 neurons in a circumscribed area of the somatosensory cortex were recorded and at the same time primary responses (PR) were recorded to electrical stimulation of a nerve. 2. The following type of unit responses were distinguished: A) nonbackground spikes during the PR, B) nonbackground spikes during the PR followed by an afterdischarge, C) temporary cessation of activity, and D) nonbackground spikes during the PR followed by temporary cessation of activity. The number of neurons with responses of type A is greatest in all series of experiments. The response of the type B neurons is most marked when general anesthesia subsides, while the type C response is most marked under moderately deep anesthesia and the type D response during strychnine poisoning. 3. Latent periods of single unit responses in all series of experiments lie approximately between 6 and 50 msec, and two-thirds of all neurons responding to nerve stimulation with nonbackground spikes begin to discharge in the positive phase of the PR. Several groups of neurons, presumably located successively in the chain of neurons processing a stimulus arriving from the periphery, can be distinguished on the basis of latent periods of their discharges, their variability, and depth of recording. 4. The positive phase of the PR is due to depolarization of neurons lying at a depth of 800–1400 μ, and the negative phase to hyperpolarization of the same neurons at deep levels and also, perhaps, to depolarization of apical dendrites of neurons in an inactive state.

ACUTE AND CHRONIC PARIETAL LOBE ABLATIONS IN MONKEYS

ACUTE AND CHRONIC PARIETAL LOBE ABLATIONS IN MONKEYS