Limits on plasticity in somatosensory cortex of adult rats: hindlimb cortex is not reactivated after dorsal column section

1995 ◽  
Vol 73 (4) ◽  
pp. 1537-1546 ◽  
Author(s):  
N. Jain ◽  
S. L. Florence ◽  
J. H. Kaas
Keyword(s):  
Spinal Cord ◽  
Somatosensory Cortex ◽  
Dorsal Column ◽  
The Body ◽  
Primary Somatosensory Cortex ◽  
Cholera Toxin B Subunit ◽  
Body Parts ◽  
Adult Rats ◽  
Dorsal Funiculus ◽  
Nucleus Gracilis

1. To better understand the limits and extents of plasticity in sensory systems of adult mammals, we unilaterally sectioned the dorsal funiculus at thoracic levels in nine adult rats to deactivate ascending afferents from the hindpaw and lower body. After postsurgical recovery periods of 3 h to 3 mo, the region of primary somatosensory cortex (S1) representing the limbs and trunk was extensively mapped with microelectrodes. 2. Recording sites were later identified as being within the hindlimb representation and other parts of S1 by relating locations of microlesions to the cytochrome oxidase pattern in sections of cortex cut tangential to the pial surface. The extent and effectiveness of spinal cord lesions were evaluated by injecting cholera toxin B subunit conjugated with horseradish peroxidase (B-HRP) at various sites in the deafferented hindpaw. 3. In five animals with complete section of the dorsal funiculus, we failed to detect any response to cutaneous stimulation of any part of the body in the deafferented hindlimb cortex. In four other animals with incomplete lesions, neurons in some penetrations could be activated by hindlimb stimulation, but not by stimulating other body parts. In those cases without activation of hindlimb cortex, B-HRP was detected in the spinal cord only caudal to the lesion, and it was not transported to the nucleus gracilis. Limited transport past the lesion to nucleus gracilis was detected in cases with incomplete lesions. 4. The results indicate that forelimb inputs do not substitute for missing hindlimb inputs in primary somatosensory cortex in rats and that the potential for somatotopic reorganization is more limited than previously thought.

Delayed Glial Cell Death Following Wallerian Degeneration in White Matter Tracts after Spinal Cord Dorsal Column Cordotomy in Adult Rats

2001 ◽  
Vol 168 (2) ◽  
pp. 213-224 ◽  
Author(s):  
Patricia Warden ◽  
Norman I. Bamber ◽  
Huaying Li ◽  
Andrew Esposito ◽  
Kaashif A. Ahmad ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Cell Death ◽  
White Matter ◽  
Glial Cell ◽  
Wallerian Degeneration ◽  
Dorsal Column ◽  
Adult Rats ◽  
White Matter Tracts ◽  
Spinal Cord Dorsal

Multiple representations of the body within the primary somatosensory cortex of primates

Science ◽  
1979 ◽  
Vol 204 (4392) ◽  
pp. 521-523 ◽  
Author(s):  
J. Kaas ◽  
R. Nelson ◽  
M Sur ◽  
C. Lin ◽  
M. Merzenich
Keyword(s):  
Somatosensory Cortex ◽  
Multiple Representations ◽  
The Body ◽  
Primary Somatosensory Cortex

scholarly journals Somatotopic Arrangement of the Human Primary Somatosensory Cortex Derived From Functional Magnetic Resonance Imaging

2021 ◽  
Vol 14 ◽  
Author(s):  
W. R. Willoughby ◽  
Kristina Thoenes ◽  
Mark Bolding
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Somatosensory Cortex ◽  
Blood Oxygen Level Dependent ◽  
The Body ◽  
Primary Somatosensory Cortex ◽  
Entire Body ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging

Functional magnetic resonance imaging (fMRI) was used to estimate neuronal activity in the primary somatosensory cortex of six participants undergoing cutaneous tactile stimulation on skin areas spread across the entire body. Differences between the accepted somatotopic maps derived from Penfield's work and those generated by this fMRI study were sought, including representational transpositions or replications across the cortex. MR-safe pneumatic devices mimicking the action of a Wartenberg wheel supplied touch stimuli in eight areas. Seven were on the left side of the body: foot, lower, and upper leg, trunk beneath ribcage, anterior forearm, middle fingertip, and neck above the collarbone. The eighth area was the glabella. Activation magnitude was estimated as the maximum cross-correlation coefficient at a certain phase shift between ideal time series and measured blood oxygen level dependent (BOLD) time courses on the cortical surface. Maximally correlated clusters associated with each cutaneous area were calculated, and cortical magnification factors were estimated. Activity correlated to lower limb stimulation was observed in the paracentral lobule and superomedial postcentral region. Correlations to upper extremity stimulation were observed in the postcentral area adjacent to the motor hand knob. Activity correlated to trunk, face and neck stimulation was localized in the superomedial one-third of the postcentral region, which differed from Penfield's cortical homunculus.

Influence of somatosensory cortex on different classes of cat motor cortex output neuron

1989 ◽  
Vol 62 (2) ◽  
pp. 487-494 ◽  
Author(s):  
P. Zarzecki
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Somatosensory Cortex ◽  
Red Nucleus ◽  
Primary Somatosensory Cortex ◽  
Reticular Nucleus ◽  
Cerebral Peduncle ◽  
Antidromic Activation ◽  
Efferent Neurons ◽  
Layer V

1. Multiple output pathways originate from motor cortex. In this study on cats, six classes of corticofugal neurons were identified by antidromic activation. Corticocallosal neurons of layer III were activated antidromically by stimulation of contralateral motor cortex. Layer V neurons were identified by antidromic activation from cerebral peduncle, red nucleus, lateral reticular nucleus of medulla, or spinal cord. Corticothalamic neurons were identified in layer VI. All the identified neurons were tested for input from primary somatosensory cortex. 2. Neurons of all corticofugal groups received excitatory inputs from primary somatosensory cortex. The shortest latency corticocortical effects of 1.2-2.5 ms were found for corticocallosal neurons of layer III, and for layer V neurons which projected axons through the cerebral peduncle, to red nucleus, and to spinal cord. 3. Nearby neurons, projecting to the same of different targets, were affected nonuniformly by corticocortical inputs. This finding supports the conclusion that specificity of afferent connections within cerebral cortex is not determined by anatomic segregation of cell bodies nor by projection target of efferent neurons. 4. These selectively distributed input connectivities suggest that even a small region of motor cortex could send different signals to its diverse targets.

The Origin of the Interoceptive Pathway

2014 ◽  
Author(s):  
A. D. (Bud) Craig
Keyword(s):  
Spinal Cord ◽  
Motor Function ◽  
Contralateral Side ◽  
Dorsal Column ◽  
The Body ◽  
Sensory Loss ◽  
Anatomical Basis ◽  
Touch Sensation ◽  
Temperature Sensations ◽  
The Brain

This chapter describes the functional and anatomical characteristics of interoceptive processing at the levels of the primary sensory fiber and the spinal cord. The association of the spinothalamic pathway with pain and temperature had already been described in textbooks for years. The clinical evidence indicated that a knife cut that severed the spinal cord on one side produced a loss of pain and temperature sensations only on the opposite (contralateral) side of the body, as tested with pinprick and a cold brass rod, combined with the loss of discriminative touch sensation and skeletal motor function on the same (ipsilateral) side as the injury to the spinal cord. The anatomical basis for this dissociated pattern of sensory loss is the distinctness of the two ascending somatosensory pathways to the brain-discriminative touch sensation in the uncrossed (ipsilateral) dorsal column pathway, and pain and temperature sensations in the crossed (contralateral) spinothalamic pathway.

scholarly journals Functional role of exercise-induced cortical organization of sensorimotor cortex after spinal transection

2011 ◽  
Vol 106 (5) ◽  
pp. 2662-2674 ◽  
Author(s):  
T. Kao ◽  
J. S. Shumsky ◽  
E. B. Knudsen ◽  
M. Murray ◽  
K. A. Moxon
Keyword(s):  
Spinal Cord ◽  
Neuronal Activity ◽  
Functional Recovery ◽  
Cortical Neurons ◽  
The Body ◽  
Cortical Reorganization ◽  
Neuron Activity ◽  
Adult Rats ◽  
Cortical Organization ◽  
Cord Injury

Spinal cord transection silences neuronal activity in the deafferented cortex to cutaneous stimulation of the body and untreated animals show no improvement in functional outcome (weight-supported stepping) with time after lesion. However, adult rats spinalized since neonates that receive exercise therapy exhibit greater functional recovery and exhibit more cortical reorganization. This suggests that the change in the somatotopic organization of the cortex may be functionally relevant. To address this issue, we chronically implanted arrays of microwire electrodes into the infragranular layers of the hindlimb somatosensory cortex of adult rats neonatally transected at T8/T9 that received exercise training (spinalized rats) and of normal adult rats. Multiple, single neuron activity was recorded during passive sensory stimulation, when the animals were anesthetized, and during active sensorimotor stimulation during treadmill-induced locomotion when the animal was awake and free to move. Our results demonstrate that cortical neurons recorded from the spinalized rats that received exercise 1) had higher spontaneous firing rates, 2) were more likely to respond to both sensory and sensorimotor stimulations of the forelimbs, and also 3) responded with more spikes per stimulus than those recorded from normal rats, suggesting expansion of the forelimb map into the hindlimb map. During treadmill locomotion the activity of neurons recorded from neonatally spinalized rats was greater during weight-supported steps on the treadmill compared with the neuronal activity during nonweight supported steps. We hypothesize that this increased activity is related to the ability of the animal to take weight supported steps and that, therefore, these changes in cortical organization after spinal cord injury are relevant for functional recovery.

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