FIG. 2.

Effect of low-level laser light therapy (LLLT) on recovery of cognitive function after controlled cortical impact (CCI). Cognitive function was assessed using the Morris water maze. In the open craniotomy group, (A) mice treated with 60 J/cm² performed significantly better than controls in the hidden platform (p=0.03 for group; n=22; upper panel) and probe trials (*p=0.004; lower panel). (B) Treatment with doses of 30 or 120 J/cm² did not improve hidden platform trials (p>0.1 for group; n=7–10/group; upper panel), but mice treated with 120 J/cm² had improved probe trial scores compared to controls (*p=0.02; lower panel). (C) Injured mice treated with 105 J/cm² performed similarly to controls (p>0.05 for group effect on the hidden platform and probe trials; n=7/group). Mice treated with 210 J/cm² had improved performance in the hidden platform (p=0.039 for group; n=8; upper panel), but not in the probe trials (p=0.95; lower panel). In mice treated with transcranial LLLT, (D) a single dose of 60 J/cm² given 60–80 min post-injury improved hidden platform trial performance (p=0.018 for group; n=12–13/group; upper panel), and probe trial latency (*p=0.021 versus controls; lower panel). (E) Daily application of transcranial LLLT for 7 days after CCI had no benefit on the hidden platform trials (p=0.935 for group; n=10/group; upper panel); however, this regimen improved probe trial performance (*p<0.03 versus controls; lower panel). (F) Transcranial LLLT (60 J/cm²) administered at 4 h post-injury did not improve hidden platform (p=0.13 for group; n=9/group; upper panel) or probe trial performance (p=0.6 versus controls; lower panel). No significant differences among treatment groups were observed in the visible platform trials. All LLLT-treated and control (non-treated) mice showed progressive improvement in the hidden platform trials (p<0.0001 for time), indicating learning.