Biology subjects

Albertson, A. J.

Publications and source records attributed to Albertson, A. J..

3 recordsLinked to original sources

bioRxiv2026

Normal Aging Limits Cortical Network Reorganization and Behavioral Recovery after Experimental Stroke

Stroke is the leading cause of chronic disability in the United States, and advancing age is associated with worse recovery. Despite this, relatively little is known about how aging influences the repair and reorganization of neural circuits and large-scale cortical networks after stroke. To address this question, we compared cortical network dynamics and behavioral recovery after focal photothrombotic stroke in forepaw somatosensory cortex in young (3-month-old) and aged (18-month-old) Thy1-GCaMP6f mice. Both young and aged mice developed significant somatomotor deficits after stroke; however, only young mice exhibited substantial behavioral recovery despite similar infarct volumes across groups. Two age-dependent effects on cortical network function emerged. First, somatosensory-evoked activity and somatosensory functional connectivity were disrupted in both cohorts early after stroke, but their trajectories diverged over time. Forepaw-evoked GCaMP responses in the affected cortex were similarly reduced in both groups early after stroke; yet by 7 weeks, responses recovered in young mice but remained persistently depressed in aged animals. Likewise, bihemispheric somatosensory functional connectivity was initially disrupted in both groups but improved between 1 and 7 weeks only in young mice. Second, global temporal measures of network function evolved differently after stroke. At baseline, stimulus-locked fidelity and interhemispheric coherence were higher in young than aged mice, but after stroke, these measures declined in young animals to levels comparable to aged mice and did not recover by 7 weeks. Stroke also altered large-scale cortical entrainment dynamics, and reductions in cortical entrainment area between baseline and 1-week post-stroke predicted long-term behavioral recovery across animals. Together, these findings indicate that impaired behavioral recovery in aged mice reflects a failure of damaged somatosensory networks to reorganize, whereas recovery in young mice occurs despite persistent degradation of global network fidelity and coherence. These results highlight age-dependent mechanisms of circuit repair after stroke and suggest a potential network-level basis for chronic deficits in stroke survivors. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=65 SRC="FIGDIR/small/720447v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@1f23999org.highwire.dtl.DTLVardef@1a3a433org.highwire.dtl.DTLVardef@712dd5org.highwire.dtl.DTLVardef@780eaa_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Stroke and Motor Recovery are Associated with Regional and Age-Specific Changes in Periodic and Aperiodic Cortical Activity

Normal aging is associated with widespread changes in neuronal structure, function, and activity. The consequences of focal brain injury on global neuronal activity in aged individuals are poorly understood. Historically, stroke and aging have been associated with changes in narrow-band periodic neuronal activity, however recent work has highlighted the importance of broad-band aperiodic activity. Aperiodic activity is represented by the 1/f slope of power spectral density generated by cortical activity. Abnormalities in aperiodic activity have been identified in psychiatric disorders and stroke, are associated with cognitive dysfunction in aging, and have been hypothesized to reflect changes in excitation/inhibition balance. Here we sought to further explore changes in both periodic and aperiodic cortical activity in neurotypical intact young and aged healthy individuals and individuals with stroke. We compared "resting state" electroencephalograms from all participants after applying the specparam algorithm, which decomposes the power spectrum into aperiodic and periodic components. We also correlated stroke outcomes using previously obtained tests of motor outcome (box and block) to average whole cortex spectral slopes within the stroke group. Consistent with prior work we found a significant flattening (decrease in exponent) of power spectral slope with normal aging. We also found that both aging and stroke were associated with fewer periodic peaks within the power spectrum. Interestingly, we found that stroke was associated with a significant increase in spectral slope, but age moderated this effect. Younger stroke patients showed minimal difference in slope while older stroke patients had significantly steeper slopes (opposite to the direction in normal aging). Using MRIs from stroke participants we investigated the lesion locations most associated with changes in slope. Interestingly deep lesions were observed to have the greatest influence on cortical spectral slope. Finally, slope in the stroke group was correlated with performance on a test of manual dexterity, however this correlation was much more significant in aged individuals. Our data suggest that stroke in the aged brain has unique effects on aperiodic activity possibly reflecting unique influence of injury on cerebral excitation/inhibition balance in aged individuals and that the degree of these changes may be related to stroke outcomes.

neuroscience↗

bioRxiv2021

Normal Aging in Mice is Associated with a Global Reduction in Cortical Spectral Power and a Network-Specific Decline in Functional Connectivity

Normal aging is associated with a variety of neurologic changes including declines in cognition, memory, and motor activity. These declines correlate with neuronal changes in synaptic structure and function. Degradation of brain network activity and connectivity represents a likely mediator of age-related functional deterioration resulting from these neuronal changes. Human studies have demonstrated both general decreases in spontaneous cortical activity and disruption of cortical networks with aging. Current techniques used to study cerebral network activity are hampered either by limited spatial resolution (e.g. electroencephalography, EEG) or limited temporal resolution (e.g., functional magnetic resonance imaging, fMRI). Here we utilize mesoscale imaging of neuronal activity in Thy1-GCaMP6f mice to characterize neuronal network changes in aging with high spatial resolution across a wide frequency range. We show that while evoked activity is unchanged with aging, spontaneous neuronal activity decreases across a wide frequency range (0.01-4Hz) involving all regions of the cortex. In contrast to this global reduction in cortical power, we found that aging is associated with functional connectivity (FC) deterioration of select networks including somatomotor, cingulate, and retrosplenial nodes. These changes are corroborated by reductions in homotopic FC and node degree within somatomotor and visual cortices. Finally, we found that whole cortex delta power and delta band node degree correlate with exploratory activity in young but not aged animals. Together these data suggest that aging is associated with global declines in spontaneous cortical activity and focal deterioration of network connectivity, and that these reductions may be associated with age-related behavioral declines.

neuroscience↗