Increased cortical responses to forepaw stimuli immediately after peripheral deafferentation of hindpaw inputs

Abstract

Both central and peripheral injuries of the nervous system induce dramatic reorganization of the primary somatosensory cortex. We recently showed that spinal cord injuries at thoracic level in anesthetized rats can immediately increase the responses evoked in the forepaw cortex by forepaw stimuli (above the level of the lesion), suggesting that the immediate cortical reorganization after deafferentation can extend across cortical representations of different paws. Here we show that a complete deafferentation of inputs from the hindpaw induced by injury or pharmacological block of the peripheral nerves in anesthetized rats also increases the responses evoked in the forepaw cortex by forepaw stimuli. This increase of cortical responses after peripheral deafferentation is not associated with gross alterations in the state of cortical spontaneous activity. The results of the present study, together with our previous works on spinal cord injury, suggest that the forepaw somatosensory cortex is critically involved in the reorganization that starts immediately after central or peripheral deafferentation of hindpaw inputs.

Stimulus-Driven Cortical Hyperexcitability in Individuals with Charles Bonnet Hallucinations

“…A neurophysiologically and computationally plausible explanation for increases in spontaneous activity is that deafferentation leads to visual cortical hyperexcitability [14,15]. Such hyperexcitability commonly follows deafferentation of inputs from the spinal cord [16], cortex [17], and peripheral sense organs [18][19][20][21] and can affect both spontaneous and input-driven activity of deafferented neurons [16,17,20]. In fact, hyperexcitability may occur spontaneously in homeostatic information systems deprived of input, as recently demonstrated by a deep neural network simulation of CBS [14].…”

Recruitment of Polysynaptic Connections Underlies Functional Recovery of a Neural Circuit after Lesion

“…In mice, experimentally induced stroke reduced the response evoked by limb stimulation contralateral to the stroke, but it enhanced responses in the unaffected cortex to sensory stimulation of either contralateral or ipsilateral pathways within 30–50 min of stroke onset (Mohajerani et al, 2011). Immediate functional reorganization in the primary somatosensory cortex has been reported in rats after lesion to the spinal cord or a peripheral nerve (Aguilar et al, 2010; Humanes-Valera et al, 2013, 2014; Moxon et al, 2014; Yagüe et al, 2014). In the cat spinal cord, locomotor ability can be recovered quickly within 24 h after a complete spinalization if the animal had previously experienced a spinal hemisection (Barrière et al, 2008).…”

Distinct patterns of activity in individual cortical neurons and local networks in primary somatosensory cortex of mice evoked by square-wave mechanical limb stimulation

“…Given that rodents are a prominent animal model used to study recovery of reaching and upper limb use after central nervous system damage or disability [11,12], it is important to understand how different forms of somatic and movement related stimuli used in rodent research are processed in the rodent somatosensory cortex. Most current research on the limb-associated somatosensory cortex in rodents utilize artificial forms of mechanical [1,[13][14][15][16][17] or electrical stimuli [18][19][20][21][22] to assess sensory-evoked responses using electrophysiology of individual cells or aggregate responses from large cortical regions. Artificial stimuli used for rodent research that may be thought of as relatively simple in comparison to naturalistic stimuli or movements, such as limb oscillation through a single axis of motion, still likely result in the generation of complex multimodal sensory information in the periphery.…”