scholarly journals Emergent Spatial Patterns of Excitatory and Inhibitory Synaptic Strengths Drive Somatotopic Representational Discontinuities and their Plasticity in a Computational Model of Primary Sensory Cortical Area 3b

2016 ◽  
Vol 10 ◽  
Author(s):  
Kamil A. Grajski
Keyword(s):  
Computational Model ◽  
Spatial Patterns ◽  
Cortical Area ◽  
Area 3B

scholarly journals A canonical computational model of cortical area V2

2019 ◽  
Vol 19 (10) ◽  
pp. 14b
Author(s):  
Timothy D Oleskiw ◽  
Eero P Simoncelli
Keyword(s):  
Computational Model ◽  
Cortical Area ◽  
Area V2

Plasticity of Primary Somatosensory Cortex Paralleling Sensorimotor Skill Recovery From Stroke in Adult Monkeys

1998 ◽  
Vol 79 (4) ◽  
pp. 2119-2148 ◽  
Author(s):  
Christian Xerri ◽  
Michael M. Merzenich ◽  
Bret E. Peterson ◽  
William Jenkins
Keyword(s):  
Somatosensory Cortex ◽  
Skill Acquisition ◽  
Cortical Area ◽  
Receptive Fields ◽  
Field Size ◽  
Primary Somatosensory Cortex ◽  
Small Object ◽  
Object Retrieval ◽  
Area 3A ◽  
Area 3B

Xerri, Christian, Michael M. Merzenich, Bret E. Peterson, and William Jenkins. Plasticity of primary somatosensory cortex paralleling sensorimotor skill recovery from stroke in adult monkeys. J. Neurophysiol. 79: 2119–2148, 1998. Adult owl and squirrel monkeys were trained to master a small-object retrieval sensorimotor skill. Behavioral observations along with positive changes in the cortical area 3b representations of specific skin surfaces implicated specific glabrous finger inputs as important contributors to skill acquisition. The area 3b zones over which behaviorally important surfaces were represented were destroyed by microlesions, which resulted in a degradation of movements that had been developed in the earlier skill acquisition. Monkeys were then retrained at the same behavioral task. They could initially perform it reasonably well using the stereotyped movements that they had learned in prelesion training, although they acted as if key finger surfaces were insensate. However, monkeys soon initiated alternative strategies for small object retrieval that resulted in a performance drop. Over several- to many-week-long period, monkeys again used the fingers for object retrieval that had been used successfully before the lesion, and reacquired the sensorimotor skill. Detailed maps of the representations of the hands in SI somatosensory cortical fields 3b, 3a, and 1 were derived after postlesion functional recovery. Control maps were derived in the same hemispheres before lesions, and in opposite hemispheres. Among other findings, these studies revealed the following 1) there was a postlesion reemergence of the representation of the fingertips engaged in the behavior in novel locations in area 3b in two of five monkeys and a less substantial change in the representation of the hand in the intact parts of area 3b in three of five monkeys. 2) There was a striking emergence of a new representation of the cutaneous fingertips in area 3a in four of five monkeys, predominantly within zones that had formerly been excited only by proprioceptive inputs. This new cutaneous fingertip representation disproportionately represented behaviorally crucial fingertips. 3) There was an approximately two times enlargement of the representation of the fingers recorded in cortical area 1 in postlesion monkeys. The specific finger surfaces employed in small-object retrieval were differentially enlarged in representation. 4) Multiple-digit receptive fields were recorded at a majority of emergent, cutaneous area 3a sites in all monkeys and at a substantial number of area 1 sites in three of five postlesion monkeys. Such fields were uncommon in area 1 in control maps. 5) Single receptive fields and the component fields of multiple-digit fields in postlesion representations were within normal receptive field size ranges. 6) No significant changes were recorded in the SI hand representations in the opposite (untrained, intact) control hemisphere. These findings are consistent with “substitution” and “vicariation” (adaptive plasticity) models of recovery from brain damage and stroke.

Changes in the distributed temporal response properties of SI cortical neurons reflect improvements in performance on a temporally based tactile discrimination task

1992 ◽  
Vol 67 (5) ◽  
pp. 1071-1091 ◽  
Author(s):  
G. H. Recanzone ◽  
M. M. Merzenich ◽  
C. E. Schreiner
Keyword(s):  
Cortical Neurons ◽  
Cortical Area ◽  
Discrimination Task ◽  
Tactile Stimulus ◽  
Discrimination Performance ◽  
Frequency Discrimination ◽  
Temporal Response ◽  
Owl Monkeys ◽  
Control Skin ◽  
Area 3B

1. Temporal response characteristics of neurons were sampled in fine spatial grain throughout the hand representations in cortical areas 3a and 3b in adult owl monkeys. These monkeys had been trained to detect small differences in tactile stimulus frequencies in the range of 20-30 Hz. Stimuli were presented to an invariant, restricted spot on a single digit. 2. The absolute numbers of cortical locations and the cortical area over which neurons showed entrained frequency-following responses to behaviorally important stimuli were significantly greater when stimulation was applied to the trained skin, as compared with stimulation on an adjacent control digit, or at corresponding skin sites in passively stimulated control animals. 3. Representational maps defined with sinusoidal stimuli were not identical to maps defined with just-visible tapping stimuli. Receptive-field/frequency-following response site mismatches were recorded in every trained monkey. Mismatches were less frequently recorded in the representations of control skin surfaces. 4. At cortical locations with entrained responses, neither the absolute firing rates of neurons nor the degree of the entrainment of the response were correlated with behavioral discrimination performance. 5. All area 3b cortical locations with entrained responses evoked by stimulation at trained or untrained skin sites were combined to create population peristimulus time and cycle histograms. In all cases, stimulation of the trained skin resulted in 1) larger-amplitude responses, 2) peak responses earlier in the stimulus cycle, and 3) temporally sharper responses, than did stimulation applied to control skin sites. 6. The sharpening of the response of cortical area 3b neurons relative to the period of the stimulus could be accounted for by a large subpopulation of neurons that had highly coherent responses. 7. Analysis of cycle histograms for area 3b neuron responses revealed that the decreased variance in the representation of each stimulus cycle could account for behaviorally measured frequency discrimination performance. A strong correlation between these temporal response distributions and the discriminative performances for stimuli applied at all studied skin surfaces was even stronger (r = 0.98) if only the rising phases of cycle histogram were considered in the analysis. 8. The responses of neurons in area 3a could not account for measured differences in frequency discrimination performance. 9. These representational changes did not occur in monkeys that were stimulated on the same schedule but were performing an auditory discrimination task during skin stimulation. 10. It is concluded that by behaviorally training adult owl monkeys to discriminate the temporal features of a tactile stimulus, distributed spatial and temporal response properties of cortical neurons are altered.(ABSTRACT TRUNCATED AT 400 WORDS)

Computational Model of the Role of Sensory Disorganization in Focal Task-Specific Dystonia

2000 ◽  
Vol 84 (5) ◽  
pp. 2458-2464 ◽  
Author(s):  
Terence D. Sanger ◽  
Michael M. Merzenich
Keyword(s):  
Computational Model ◽  
Cortical Area ◽  
Motor Behavior ◽  
Loop Transformation ◽  
Task Specificity ◽  
Abnormal Motor ◽  
Focal Task ◽  
Over Time ◽  
And Task

We present a new computational model for the development of task-specific focal dystonia. The purpose of the model is to explain how altered sensory representations can lead to abnormal motor behavior. Dystonia is described as the result of excessive gain through a sensorimotor loop. The gain is determined in part by the sensory cortical area devoted to each motor function, and behaviors that lead to abnormal increases in sensory cortical area are predicted to lead to dystonia. Properties of dystonia including muscular co-contraction, overflow movements, and task specificity are predicted by properties of a linear approximation to the loop transformation. We provide simulations of several different mechanisms that can cause the gain to exceed 1 and the motor activity to become sustained and uncontrolled. The model predicts that normal plasticity mechanisms may contribute to worsening of symptoms over time.

Receptive field structure in cortical area 3b of the alert monkey

2002 ◽  
Vol 135 (1-2) ◽  
pp. 167-178 ◽  
Author(s):  
James J DiCarlo ◽  
Kenneth O Johnson
Keyword(s):  
Receptive Field ◽  
Cortical Area ◽  
Field Structure ◽  
Alert Monkey ◽  
Area 3B
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