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Left parahippocampal gyrus activity during language generation
NemoImage
13, Number
6, 2001, Part 2 of 2 Parts ID
E al@
LANGUAGE
Left Parahippocampal
Gyrus Activity during Language Generation
Bruce Crosson*, Hope Benefield”, M. Allison Cato*, Joseph R. Sadekt, Kaundinya Gopinath*, David Soltysik*, Russell M. Bauer *, Edward J. AuerbachS, Didem Gokcay*, Christiana M. Leonard*, Richard W. Briggs* *MeKnight Brain Institute at the University of Florida tSection of Neuropsychology, Medical College of Wisconsin $ University of Minnesota Documenting medial temporal activity during memory encoding and retrieval can experiments. In the current study, left posterior parahippocampal gyms (LPPHG) activity retrieval tasks. This finding has implications for verbal memory experiments.
be difficult was related
in functional neuroimaging to semantic demands in word
Method Twenty-one right-handed native English speakers (12 M, 9 F; age 18-38 yrs) performed 4 language generation tasks: [a] generating as many nonsense syllables as possible given beginning and ending consonant blends, [b] for a given word, generating as many rhyming words as possible, [c and d] generating as many exemplars as possible from a given category. In fast exemplar generation, categories were matched to the generation rate of nonsense syllables. In slow exemplar generation, categories were matched to the generation rate for rhyming words. In two separate imaging runs for each task, six 17.4 s periods of generating words or syllables alternated with 6.8 resting baseline periods of 17.4 s. A 1.5 T GE Signa scanner and a dome-shaped quadrature RF head coil were used with a gradient echo spiral scan sequence (TE=40 ms; TR= 1740 ms; FA=60 deg; FOV=18 cm; 2 spirals) for functional images. During each task-rest cycle, 10 images were acquired for each of 22 sagittal slices (6.5 to 7.0 mm thick), covering the entire brain. Images were corrected for 3-dimensional motion. Functional intensities were magnitude of the least-squares fit between the best of 9 phase-shifted sinusoidal reference waveforms and the acquired time series. After functional images were overlaid onto Tl-weighted spoiled GRASS anatomic images, functional images were averaged across Fig. la. semantic generation 1 Fig. lb. semantic generation > runs for each task. Functional and anatomic images were syllable generation rhyme generation interpolated to 1 mm cubed voxels and converted to atlas space (1). Functional images were smoothed (3 mm FWHM). Functional intensities for task-rest alternations were compared between tasks using voxel-by-voxel t-tests and a threshold of p < ,001. Results
and Discussion
Robust activity occupied the LPPHG for exemplar generation (fast) compared to nonsense syllable generation (Fig. la). A small volume of activity appeared in the LPPHG for semantic generation (slow) compared to rhyme generation (Fig. 1b). Comparison of rhyme generation to nonsense syllable generation produced no activity difference in the LPPHG (Fig. lc). Results indicate that a verbal generation task focusing on semantic retrieval engages the LPPHG, even with no recent memory demands. In previous studies,the posterior parahippocampal gyrus showed increased activity during encoding into (2,3,4) or retrieval from (5) recent memory. Verbal tasks requiring semantic processing may be poor comparison tasks for verbal memory experiments exploring medial temporal functions because of LPPHG activity.
Fig. le. rhyme lable generation
References (1) (2) (3) (4) (5)
Talairach, J & Toumoux, P. Co-Planar Stereotaxic Atlas of the Human Gabrieli, JDE et al. Science, 1997, 276:264-266. Rombouts, SARB et al. Hippocampus, 1999, 9:637-643. Stem, CE et al. Proc. Natl. Acad. Sci. USA, 1996, 93:8660-8665. DuPont, S et al. Brain, 2000, 123:1722-1723.
Supported
by NIH
grant
DC03455
S521
Brain,
1988. New
York:
Thieme.
generation
> syl-
13, Number
6, 2001, Part 2 of 2 Parts ID
E al@
LANGUAGE
Left Parahippocampal
Gyrus Activity during Language Generation
Bruce Crosson*, Hope Benefield”, M. Allison Cato*, Joseph R. Sadekt, Kaundinya Gopinath*, David Soltysik*, Russell M. Bauer *, Edward J. AuerbachS, Didem Gokcay*, Christiana M. Leonard*, Richard W. Briggs* *MeKnight Brain Institute at the University of Florida tSection of Neuropsychology, Medical College of Wisconsin $ University of Minnesota Documenting medial temporal activity during memory encoding and retrieval can experiments. In the current study, left posterior parahippocampal gyms (LPPHG) activity retrieval tasks. This finding has implications for verbal memory experiments.
be difficult was related
in functional neuroimaging to semantic demands in word
Method Twenty-one right-handed native English speakers (12 M, 9 F; age 18-38 yrs) performed 4 language generation tasks: [a] generating as many nonsense syllables as possible given beginning and ending consonant blends, [b] for a given word, generating as many rhyming words as possible, [c and d] generating as many exemplars as possible from a given category. In fast exemplar generation, categories were matched to the generation rate of nonsense syllables. In slow exemplar generation, categories were matched to the generation rate for rhyming words. In two separate imaging runs for each task, six 17.4 s periods of generating words or syllables alternated with 6.8 resting baseline periods of 17.4 s. A 1.5 T GE Signa scanner and a dome-shaped quadrature RF head coil were used with a gradient echo spiral scan sequence (TE=40 ms; TR= 1740 ms; FA=60 deg; FOV=18 cm; 2 spirals) for functional images. During each task-rest cycle, 10 images were acquired for each of 22 sagittal slices (6.5 to 7.0 mm thick), covering the entire brain. Images were corrected for 3-dimensional motion. Functional intensities were magnitude of the least-squares fit between the best of 9 phase-shifted sinusoidal reference waveforms and the acquired time series. After functional images were overlaid onto Tl-weighted spoiled GRASS anatomic images, functional images were averaged across Fig. la. semantic generation 1 Fig. lb. semantic generation > runs for each task. Functional and anatomic images were syllable generation rhyme generation interpolated to 1 mm cubed voxels and converted to atlas space (1). Functional images were smoothed (3 mm FWHM). Functional intensities for task-rest alternations were compared between tasks using voxel-by-voxel t-tests and a threshold of p < ,001. Results
and Discussion
Robust activity occupied the LPPHG for exemplar generation (fast) compared to nonsense syllable generation (Fig. la). A small volume of activity appeared in the LPPHG for semantic generation (slow) compared to rhyme generation (Fig. 1b). Comparison of rhyme generation to nonsense syllable generation produced no activity difference in the LPPHG (Fig. lc). Results indicate that a verbal generation task focusing on semantic retrieval engages the LPPHG, even with no recent memory demands. In previous studies,the posterior parahippocampal gyrus showed increased activity during encoding into (2,3,4) or retrieval from (5) recent memory. Verbal tasks requiring semantic processing may be poor comparison tasks for verbal memory experiments exploring medial temporal functions because of LPPHG activity.
Fig. le. rhyme lable generation
References (1) (2) (3) (4) (5)
Talairach, J & Toumoux, P. Co-Planar Stereotaxic Atlas of the Human Gabrieli, JDE et al. Science, 1997, 276:264-266. Rombouts, SARB et al. Hippocampus, 1999, 9:637-643. Stem, CE et al. Proc. Natl. Acad. Sci. USA, 1996, 93:8660-8665. DuPont, S et al. Brain, 2000, 123:1722-1723.
Supported
by NIH
grant
DC03455
S521
Brain,
1988. New
York:
Thieme.
generation
> syl-