Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. III. Responses to Altered Friction Perturbations

Neuronal activity in somatosensory cortex of monkeys using a precision grip. III. Responses to altered friction perturbations. The purpose of this investigation was to examine the activity changes in single units of the somatosensory cortex in response to lubricating and adhesive coatings applied to a hand-held object. Three monkeys were trained to grasp an object between the thumb and index fingers and to lift and hold it stationary within a narrow position window for 1 s before release. Grip forces normal to the skin surface, load forces tangential to the skin surface, and the displacement of the object were measured on each trial. Adhesive (rosin) and lubricant (petroleum jelly) coatings were applied to the smooth metal surface of the object to alter the friction against the skin. In addition, neuronal activity evoked by force pulse-perturbations generating shear forces and slip on the skin were compared with the patterns of activity elicited by grasping and lifting the coated surfaces. Following changes in surface coatings, both monkeys modulated the rate at which grip forces normal to the skin surface and load forces tangential to the skin surface were applied during the lifting phase of the task. As a result, the ratio of the rates of change of the two forces was proportionately scaled to the surface coating properties with the more slippery surfaces, having higher ratios. This precise control of normal and tangential forces enabled the monkeys to generate adequate grip forces and prevent slip of the object. From a total of 386 single neurons recorded in the hand area of the somatosensory cortex, 92 were tested with at least 1 coating. Cell discharge changed significantly with changes in surface coating in 62 (67%) of these cells. Of these coating-related cells, 51 were tested with both an adhesive and lubricating coating, and 45 showed significant differences in activity between the untreated metal surface and either the lubricant or the adhesive coating. These cells were divided into three main groups on the basis of their response patterns. In the first group ( group A), the peak discharge increased significantly when the grasped surface was covered with lubricant. These cells appeared to be selectively sensitive to slip of the object on the skin. The second group ( group B) was less activated by the adhesive surface compared with either the untreated metal or the lubricated surface, and they responded mainly to variations in the force normal to the skin surface. These cells provide useful feedback for the control of grip force. The third group ( group C) responded to both slips and to changes in forces tangential to the skin. Most of these cells responded with a biphasic pattern reflecting the bidirectional changes in load force as the object was first accelerated and then decelerated. One hundred sixty-eight of the 386 isolated neurons were tested with brief perturbations during the task. Of these, 147 (88%) responded to the perturbation with a significant change in activity. In most of the cells, the response to the perturbation was shorter than 100 ms with a mean latency of 44.1 ± 16.3 (SD) ms. For each of the cell groups, the activity patterns triggered by the perturbations were consistent with the activity patterns generated during the grasping and lifting of the coated object.

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Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. II. Responses to Object Texture and Weights

Journal of Neurophysiology ◽

10.1152/jn.1999.81.2.835 ◽

1999 ◽

Vol 81 (2) ◽

pp. 835-844 ◽

Cited By ~ 18

Author(s):

Iran Salimi ◽

Thomas Brochier ◽

Allan M. Smith

Keyword(s):

Somatosensory Cortex ◽

Neuronal Activity ◽

Surface Texture ◽

Precision Grip ◽

Cell Activity ◽

Receptive Fields ◽

Surface Characteristics ◽

Skin Surface ◽

Firing Frequency ◽

Object Weight

Neuronal activity in somatosensory cortex of monkeys using a precision grip. II. Responses to object texture and weights. Three monkeys were trained to lift and hold a test object within a 12- to 25-mm position window for 1 s. The activity of single neurons was recorded during performance of the task in which both the weight and surface texture of the object were systematically varied. Whenever possible, each cell was tested with three weights (15, 65, and 115 g) and three textures (smooth metal, fine 200 grit sandpaper, and rough 60 grit sandpaper). Of 386 cells recorded in 3 monkeys, 45 cells had cutaneous receptive fields on the index or thumb or part of the thenar eminence and were held long enough to be tested in all 9 combinations of texture and weight. Recordings were made for the entire anterior-posterior extent of the thumb and index finger areas in somatosensory cortex including area 7b. However, the statistical analysis required a selection of only those cells for which nine complete recording conditions were available limiting the sample to cells in areas 2, 5, and 7b. Significant differences in the grip force accompanied 98% of the changes in texture and 78% of the changes in weight. Increasing the object weight also increased the force tangential to the skin surface as measured by the load or lifting force. The peak discharge during lifting was judged to be the most sensitive index of cell activity and was analyzed with a two-way analysis of variance (ANOVA). In addition, peak cell discharge was normalized to allow comparisons among different combinations of texture and weight as well as comparisons among different neurons. Overall, the peak firing frequency of 87% of the cells was significantly modulated by changes in object texture, but changes in object weight affected the peak activity of only 58% of the cells. Almost all (17/18, 94%) of the static cells were influenced by the object texture, and 81% of the dynamic cells that were active only briefly at grip and lift onset were modulated by texture. For some cells, surface texture had a significant effect on neuronal discharge that was independent of the object weight. In contrast, weight-related responses were never simple main effects of the weight alone and appeared instead as significant interactions between texture and weight. Four neurons either increased or decreased activity in a graded fashion with surface structure (roughness) regardless of the object weight ( P < 0.05). Ten other neurons showed increases or decreases in response to one or two textures, which might represent either a graded response or a tuning preference for a specific texture. The firing frequency of the majority (31/45) of neurons reflected an interaction of both texture and weight. The cells with texture-related but weight-independent activities were thought to encode surface characteristics that are largely independent of the grip and lifting forces used to manipulate the object. Such constancies could be used to construct internal representations or mental models for planning and controlling object manipulation.

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Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. I. Receptive Fields and Discharge Patterns

Journal of Neurophysiology ◽

10.1152/jn.1999.81.2.825 ◽

1999 ◽

Vol 81 (2) ◽

pp. 825-834 ◽

Cited By ~ 28

Author(s):

Iran Salimi ◽

Thomas Brochier ◽

Allan M. Smith

Keyword(s):

Receptive Field ◽

Somatosensory Cortex ◽

Neuronal Activity ◽

Single Cells ◽

Precision Grip ◽

Receptive Fields ◽

Pressure Change ◽

Discharge Pattern ◽

Cortical Cells ◽

Discharge Patterns

Neuronal activity in somatosensory cortex of monkeys using a precision grip. I. Receptive fields and discharge patterns. Three adolescent Macaca fascicularis monkeys weighing between 3.5 and 4 kg were trained to use a precision grip to grasp a metal tab mounted on a low friction vertical track and to lift and hold it in a 12- to 25-mm position window for 1 s. The surface texture of the metal tab in contact with the fingers and the weight of the object could be varied. The activity of 386 single cells with cutaneous receptive fields contacting the metal tab were recorded in Brodmann’s areas 3b, 1, 2, 5, and 7 of the somatosensory cortex. In this first of a series of papers, we describe three types of discharge pattern, the receptive-field properties, and the anatomic distribution of the neurons. The majority of the receptive fields were cutaneous and covered less than one digit, and a χ2 test did not reveal any significant differences in the Brodmann’s areas representing the thumb and index finger. Two broad categories of discharge pattern cells were identified. The first category, dynamic cells, showed a brief increase in activity beginning near grip onset, which quickly subsided despite continued pressure applied to the receptive field. Some of the dynamic neurons responded to both skin indentation and release. The second category, static cells, had higher activity during the stationary holding phase of the task. These static neurons demonstrated varying degrees of sensitivity to rates of pressure change on the skin. The percentage of dynamic versus static cells was about equal for areas 3b, 2, 5, and 7. Only area 1 had a higher proportion of dynamic cells (76%). A third category was identified that contained cells with significant pregrip activity and included cortical cells with both dynamic or static discharge patterns. Cells in this category showed activity increases before movement in the absence of receptive-field stimulation, suggesting that, in addition to peripheral cutaneous input, these cells also receive strong excitation from movement-related regions of the brain.

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An analog of psychedelics restores functional neural circuits disrupted by unpredictable stress

Molecular Psychiatry ◽

10.1038/s41380-021-01159-1 ◽

2021 ◽

Author(s):

Ju Lu ◽

Michelle Tjia ◽

Brian Mullen ◽

Bing Cao ◽

Kacper Lukasiewicz ◽

...

Keyword(s):

Somatosensory Cortex ◽

Neuronal Activity ◽

Sensory Processing ◽

Cognitive Deficits ◽

Neural Circuits ◽

Wide Spectrum ◽

Activity Patterns ◽

Mild Stress ◽

Brain Functions ◽

Post Stress

AbstractPsychological stress affects a wide spectrum of brain functions and poses risks for many mental disorders. However, effective therapeutics to alleviate or revert its deleterious effects are lacking. A recently synthesized psychedelic analog tabernanthalog (TBG) has demonstrated anti-addictive and antidepressant potential. Whether TBG can rescue stress-induced affective, sensory, and cognitive deficits, and how it may achieve such effects by modulating neural circuits, remain unknown. Here we show that in mice exposed to unpredictable mild stress (UMS), administration of a single dose of TBG decreases their anxiety level and rescues deficits in sensory processing as well as in cognitive flexibility. Post-stress TBG treatment promotes the regrowth of excitatory neuron dendritic spines lost during UMS, decreases the baseline neuronal activity, and enhances whisking-modulation of neuronal activity in the somatosensory cortex. Moreover, calcium imaging in head-fixed mice performing a whisker-dependent texture discrimination task shows that novel textures elicit responses from a greater proportion of neurons in the somatosensory cortex than do familiar textures. Such differential response is diminished by UMS and is restored by TBG. Together, our study reveals the effects of UMS on cortical neuronal circuit activity patterns and demonstrate that TBG combats the detrimental effects of stress by modulating basal and stimulus-dependent neural activity in cortical networks.

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Pain induces stable, active microcircuits in the somatosensory cortex that provide a therapeutic target

Science Advances ◽

10.1126/sciadv.abd8261 ◽

2021 ◽

Vol 7 (12) ◽

pp. eabd8261

Author(s):

Takuya Okada ◽

Daisuke Kato ◽

Yuki Nomura ◽

Norihiko Obata ◽

Xiangyu Quan ◽

...

Keyword(s):

Somatosensory Cortex ◽

Neuronal Activity ◽

Inflammatory Pain ◽

Neuronal Excitability ◽

Activity Patterns ◽

Neuron Activity ◽

Cellular Mechanisms ◽

Pain Models ◽

Voltage Dependent

Sustained neuropathic pain from injury or inflammation remains a major burden for society. Rodent pain models have informed some cellular mechanisms increasing neuronal excitability within the spinal cord and primary somatosensory cortex (S1), but how activity patterns within these circuits change during pain remains unclear. We have applied multiphoton in vivo imaging and holographic stimulation to examine single S1 neuron activity patterns and connectivity during sustained pain. Following pain induction, there is an increase in synchronized neuronal activity and connectivity within S1, indicating the formation of pain circuits. Artificially increasing neuronal activity and synchrony using DREADDs reduced pain thresholds. The expression of N-type voltage-dependent Ca2+ channel subunits in S1 was increased after pain induction, and locally blocking these channels reduced both the synchrony and allodynia associated with inflammatory pain. Targeting these S1 pain circuits, via inhibiting N-type Ca2+ channels or other approaches, may provide ways to reduce inflammatory pain.

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Faculty Opinions recommendation of Complementary functional organization of neuronal activity patterns in the perirhinal, lateral entorhinal, and medial entorhinal cortices.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726256296.793517909 ◽

2016 ◽

Cited By ~ 1

Author(s):

Michael Yassa ◽

Zachariah Reagh

Keyword(s):

Neuronal Activity ◽

Functional Organization ◽

Activity Patterns

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Altered somatosensory cortex neuronal activity in a rat model of Parkinson's disease and levodopa-induced dyskinesias

Experimental Neurology ◽

10.1016/j.expneurol.2017.04.011 ◽

2017 ◽

Vol 294 ◽

pp. 19-31 ◽

Cited By ~ 11

Author(s):

Mesbah Alam ◽

Regina Rumpel ◽

Xingxing Jin ◽

Christof von Wrangel ◽

Sarah K. Tschirner ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Somatosensory Cortex ◽

Neuronal Activity ◽

Rat Model

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Wrist Action Affects Precision Grip Force

Journal of Neurophysiology ◽

10.1152/jn.1997.78.1.271 ◽

1997 ◽

Vol 78 (1) ◽

pp. 271-280 ◽

Cited By ~ 53

Author(s):

Mary M. Werremeyer ◽

Kelly J. Cole

Keyword(s):

Grip Force ◽

Precision Grip ◽

Load Force ◽

Myoelectric Activity ◽

Resistive Load ◽

Wrist Flexion ◽

Wrist Extension ◽

Hand Muscles ◽

Force Pulse ◽

Grasp Stability

Werremeyer, Mary M. and Kelly J. Cole. Wrist action affects precision grip force. J. Neurophysiol. 78: 271–280, 1997. When moving objects with a precision grip, fingertip forces normal to the object surface (grip force) change in parallel with forces tangential to the object (load force). We investigated whether voluntary wrist actions can affect grip force independent of load force, because the extrinsic finger muscles cross the wrist. Grip force increased with wrist angular speed during wrist motion in the horizontal plane, and was much larger than the increased tangential load at the fingertips or the reaction forces from linear acceleration of the test object. During wrist flexion the index finger muscles in the hand and forearm increased myoelectric activity; during wrist extension this myoelectric activity increased little, or decreased for some subjects. The grip force maxima coincided with wrist acceleration maxima, and grip force remained elevated when subjects held the wrist in extreme flexion or extension. Likewise, during isometric wrist actions the grip force increased even though the fingertip loads remained constant. A grip force “pulse” developed that increased with wrist force rate, followed by a static grip force while the wrist force was sustained. Subjects could not suppress the grip force pulse when provided visual feedback of their grip force. We conclude that the extrinsic hand muscles can be recruited to assist the intended wrist action, yielding higher grip-load ratios than those employed with the wrist at rest. This added drive to hand muscles overcame any loss in muscle force while the extrinsic finger flexors shortened during wrist flexion motion. During wrist extension motion grip force increases apparently occurred from eccentric contraction of the extrinsic finger flexors. The coactivation of hand closing muscles with other wrist muscles also may result in part from a general motor facilitation, because grip force increased during isometric knee extension. However, these increases were related weakly to the knee force. The observed muscle coactivation, from all sources, may contribute to grasp stability. For example, when transporting grasped objects, upper limb accelerations simultaneously produce inertial torques at the wrist that must be resisted, and inertial loads at the fingertips from the object that must be offset by increased grip force. The muscle coactivation described here would cause similarly timed pulses in the wrist force and grip force. However, grip-load coupling from this mechanism would not contribute much to grasp stability when small wrist forces are required, such as for slow movements or when the object's total resistive load is small.

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Epileptogenesis due to glia-mediated synaptic scaling

Journal of The Royal Society Interface ◽

10.1098/rsif.2008.0387 ◽

2008 ◽

Vol 6 (37) ◽

pp. 655-668 ◽

Cited By ~ 35

Author(s):

Cristina Savin ◽

Jochen Triesch ◽

Michael Meyer-Hermann

Keyword(s):

Immune System ◽

Neuronal Activity ◽

Activity Patterns ◽

Brain Inflammation ◽

Network Activity ◽

Homeostatic Regulation ◽

Synaptic Scaling ◽

Tnf Α ◽

Factor Α ◽

Potential Interactions

Homeostatic regulation of neuronal activity is fundamental for the stable functioning of the cerebral cortex. One form of homeostatic synaptic scaling has been recently shown to be mediated by glial cells that interact with neurons through the diffusible messenger tumour necrosis factor-α (TNF-α). Interestingly, TNF-α is also used by the immune system as a pro-inflammatory messenger, suggesting potential interactions between immune system signalling and the homeostatic regulation of neuronal activity. We present the first computational model of neuron–glia interaction in TNF-α-mediated synaptic scaling. The model shows how under normal conditions the homeostatic mechanism is effective in balancing network activity. After chronic immune activation or TNF-α overexpression by glia, however, the network develops seizure-like activity patterns. This may explain why under certain conditions brain inflammation increases the risk of seizures. Additionally, the model shows that TNF-α diffusion may be responsible for epileptogenesis after localized brain lesions.

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