behavioralNot explicitly stated in provided textNot explicitly stated in provided text
Objective: To examine the role of synchronous neuronal activity in axonal sprouting after thermal-ischemic lesions of sensorimotor cortex, and to determine whether blocking this activity prevents sprouting
Materials & Equipment Checklist
5 items1 from ConductScience
Gather these items before starting the experiment. Check off items as you prepare.
Equipment4
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Protocol Steps
View Abstract
The ability of the adult brain to form new connections in areas denervated by a lesion (axonal sprouting) is more widespread than previously thought, but mechanisms remain unknown. We have previously demonstrated an unexpected, robust axonal sprouting of contralateral corticostriatal neurons into the denervated striatum after ischemic cortical lesions. We now take advantage of marked differences in the degree of axonal sprouting from contralateral homotypic cortex after two types of cortical lesions to define the role of neuronal activity in this response. Thermal–ischemic lesions (TCL) of sensorimotor cortex, which induce axonal sprouting, produced two sequential patterns of low-frequency, synchronized neuronal activity that are not seen after similarly sized aspiration lesions, which do not induce axonal sprouting. An early rhythm of synchronous neuronal activity occurred in perilesion cortex on day 1 after lesion, with a frequency range of 0.2–2 Hz. A later pattern of activity occurred on days 2 and 3 after lesion, with a frequency range of 0.1–0.4 Hz. This second rhythm synchronized neuronal activity across widespread areas, including the cortical areas that contain the cell bodies of the sprouting axons. TTX was used to block this patterned neuronal activity and determine whether axonal sprouting was prevented. Chronic TTX infusion into the lesion site blocked the synchronous neuronal activity after TCL as well as axonal sprouting. Thus, both after different types of lesions and in the blockade experiments axonal sprouting was strongly correlated with synchronous neuronal activity, suggesting a role for this activity in anatomical reorganization after brain lesion in the adult.
1
Induce thermal-ischemic lesion
Create thermal-ischemic lesions (TCL) in sensorimotor cortex of adult animals
Not explicitly statedNot explicitly stated
Note: This lesion type induces axonal sprouting and produces specific patterns of neuronal activity
View evidence from paper
“Thermal–ischemic lesions (TCL) of sensorimotor cortex, which induce axonal sprouting, produced two sequential patterns of low-frequency, synchronized neuronal activity”
2
Record neuronal activity on day 1 post-lesion
Monitor and record synchronized neuronal activity in perilesion cortex on day 1 after thermal-ischemic lesion
Day 1 after lesionNot explicitly stated
Note: Early rhythm of synchronous activity with frequency range 0.2-2 Hz
View evidence from paper
“An early rhythm of synchronous neuronal activity occurred in perilesion cortex on day 1 after lesion, with a frequency range of 0.2–2 Hz”
3
Record neuronal activity on days 2-3 post-lesion
Monitor and record synchronized neuronal activity across widespread cortical areas on days 2 and 3 after thermal-ischemic lesion
Days 2 and 3 after lesionNot explicitly stated
Note: Later pattern of activity with frequency range 0.1-0.4 Hz that synchronizes activity across areas containing cell bodies of sprouting axons
View evidence from paper
“A later pattern of activity occurred on days 2 and 3 after lesion, with a frequency range of 0.1–0.4 Hz. This second rhythm synchronized neuronal activity across widespread areas”
4
Administer chronic TTX infusion
Infuse tetrodotoxin chronically into the lesion site to block synchronous neuronal activity
Chronic infusion (duration not explicitly stated)Not explicitly stated
Note: TTX blocks patterned neuronal activity and prevents axonal sprouting
View evidence from paper
“Chronic TTX infusion into the lesion site blocked the synchronous neuronal activity after TCL as well as axonal sprouting”
5
Create control aspiration lesions
Create similarly sized aspiration lesions in control animals for comparison
Not explicitly statedNot explicitly stated
Note: Aspiration lesions do not induce axonal sprouting and do not produce the same patterns of synchronized neuronal activity
View evidence from paper
“similarly sized aspiration lesions, which do not induce axonal sprouting”
6
Assess axonal sprouting
Examine and quantify axonal sprouting of contralateral corticostriatal neurons into denervated striatum
Not explicitly statedNot explicitly stated
Note: Sprouting is correlated with synchronous neuronal activity patterns
View evidence from paper
“robust axonal sprouting of contralateral corticostriatal neurons into the denervated striatum after ischemic cortical lesions”