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Lower Left Thalamic Myo-Inositol Levels Associated with Greater Cognitive Impulsivity in Marijuana-Dependent Young Men: Preliminary Spectroscopic Evidence at 4T.

Mashhoon Y, Jensen JE, Sneider JT, Yurgelun-Todd DA, Silveri MM - J Addict Res Ther (2013)

Bottom Line: MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity.Other regional analyses did not reveal any significant group differences.The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users.

View Article: PubMed Central - PubMed

Affiliation: McLean Hospital/Harvard Medical School, 115 Mill St., Belmont, MA 02478, USA.

ABSTRACT
The effects of chronic marijuana (MRJ) use on neurochemistry are not well characterized. Previously, altered global myo-Inositol (mI) concentrations and distribution in white matter were associated with impulsivity and mood symptoms in young MRJ-dependent men. The objective of this study was to retrospectively examine previously collected data, to investigate the potential regional specificity of metabolite levels in brain regions densely packed with cannabinoid receptors. Spectra were acquired at 4.0 Tesla using 2D J-resolved proton magnetic resonance spectroscopic imaging (MRSI) to quantify the entire J-coupled spectral surface of metabolites from voxels in regions of interest. For the current regional spectral analyses, a 2D-JMRSI grid was positioned over the central axial slice and shifted in the x and y dimensions to optimally position voxels over regions containing thalamus, temporal lobe, and parieto-occipital cortex. MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity. Other regional analyses did not reveal any significant group differences. The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users. Furthermore, findings suggest that mI and the lThal uniquely contribute to elevated impulsivity.

No MeSH data available.


Related in: MedlinePlus

Axial T1-weighted images depicting MRSI grid with voxels positioned in the left and right temporal cortex (A) and in the parieto-occipital cortex (POC; C). Also shown are corresponding J=0.0 Hz sample spectra from voxels in the left (B-1) and right (B-2) temporal cortex and in the POC (D).
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Figure 2: Axial T1-weighted images depicting MRSI grid with voxels positioned in the left and right temporal cortex (A) and in the parieto-occipital cortex (POC; C). Also shown are corresponding J=0.0 Hz sample spectra from voxels in the left (B-1) and right (B-2) temporal cortex and in the POC (D).

Mentions: In order to perform regional analyses, the 2D-JMRSI grid was positioned over the central axial slice (slice number 16 or 17 of 32 total) and shifted in the x and y dimensions in the axial plane to optimally place a matrix of voxels over regions of interest. Voxels positioned over the left (lThal) and right thalamus (rThal) were placed on each side of the midline separated by the putamen (Figure 1). Voxels positioned over the left (lTC) and right temporal cortex (rTC) were placed over GM (Figures 2A, 2B-1 and 2B-2). Voxels were also placed in the POC along the midline (Figures 2C and 2D). Potential partial overlap with some adjacent structures was unavoidable in these regions due to voxel volume and shape. All remaining spectra were then automatically fitted using an optimized, two-dimensional LCModel algorithm produced from GAMMA-simulated basis sets [32], which quantifies all 32 J-resolved spectral extractions within a J-bandwidth of 25 Hz and provides two-dimensional integrals for Cho, mI, Glu, Gln, NAA, NAA + N-acetyl-aspartyl-glutamate (NAAG), and Cr. To ensure the quality of spectra that were included in the regional analyses, the J=0.0 Hz spectrum and LCModel fit for each voxel was evaluated by an experienced spectroscopist (JEJ). Sample spectra (J=0.0 Hz) from lThal voxels, as well as a sample spectrum (J=0.0 Hz) with LCModel fit and labeled metabolites are presented in figures 1A-1C). The number of voxels that produced spectra of sufficient quality, which were defined by well-resolved metabolite signals, did not differ significantly between MRJ and NU groups in any region (Table 1). Spectral data from the 2 left-handed MRJ users and 1 NU participant were excluded due to low signal-to-noise and/or poor spectral quality, likely resulting from subject movement.


Lower Left Thalamic Myo-Inositol Levels Associated with Greater Cognitive Impulsivity in Marijuana-Dependent Young Men: Preliminary Spectroscopic Evidence at 4T.

Mashhoon Y, Jensen JE, Sneider JT, Yurgelun-Todd DA, Silveri MM - J Addict Res Ther (2013)

Axial T1-weighted images depicting MRSI grid with voxels positioned in the left and right temporal cortex (A) and in the parieto-occipital cortex (POC; C). Also shown are corresponding J=0.0 Hz sample spectra from voxels in the left (B-1) and right (B-2) temporal cortex and in the POC (D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3927647&req=5

Figure 2: Axial T1-weighted images depicting MRSI grid with voxels positioned in the left and right temporal cortex (A) and in the parieto-occipital cortex (POC; C). Also shown are corresponding J=0.0 Hz sample spectra from voxels in the left (B-1) and right (B-2) temporal cortex and in the POC (D).
Mentions: In order to perform regional analyses, the 2D-JMRSI grid was positioned over the central axial slice (slice number 16 or 17 of 32 total) and shifted in the x and y dimensions in the axial plane to optimally place a matrix of voxels over regions of interest. Voxels positioned over the left (lThal) and right thalamus (rThal) were placed on each side of the midline separated by the putamen (Figure 1). Voxels positioned over the left (lTC) and right temporal cortex (rTC) were placed over GM (Figures 2A, 2B-1 and 2B-2). Voxels were also placed in the POC along the midline (Figures 2C and 2D). Potential partial overlap with some adjacent structures was unavoidable in these regions due to voxel volume and shape. All remaining spectra were then automatically fitted using an optimized, two-dimensional LCModel algorithm produced from GAMMA-simulated basis sets [32], which quantifies all 32 J-resolved spectral extractions within a J-bandwidth of 25 Hz and provides two-dimensional integrals for Cho, mI, Glu, Gln, NAA, NAA + N-acetyl-aspartyl-glutamate (NAAG), and Cr. To ensure the quality of spectra that were included in the regional analyses, the J=0.0 Hz spectrum and LCModel fit for each voxel was evaluated by an experienced spectroscopist (JEJ). Sample spectra (J=0.0 Hz) from lThal voxels, as well as a sample spectrum (J=0.0 Hz) with LCModel fit and labeled metabolites are presented in figures 1A-1C). The number of voxels that produced spectra of sufficient quality, which were defined by well-resolved metabolite signals, did not differ significantly between MRJ and NU groups in any region (Table 1). Spectral data from the 2 left-handed MRJ users and 1 NU participant were excluded due to low signal-to-noise and/or poor spectral quality, likely resulting from subject movement.

Bottom Line: MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity.Other regional analyses did not reveal any significant group differences.The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users.

View Article: PubMed Central - PubMed

Affiliation: McLean Hospital/Harvard Medical School, 115 Mill St., Belmont, MA 02478, USA.

ABSTRACT
The effects of chronic marijuana (MRJ) use on neurochemistry are not well characterized. Previously, altered global myo-Inositol (mI) concentrations and distribution in white matter were associated with impulsivity and mood symptoms in young MRJ-dependent men. The objective of this study was to retrospectively examine previously collected data, to investigate the potential regional specificity of metabolite levels in brain regions densely packed with cannabinoid receptors. Spectra were acquired at 4.0 Tesla using 2D J-resolved proton magnetic resonance spectroscopic imaging (MRSI) to quantify the entire J-coupled spectral surface of metabolites from voxels in regions of interest. For the current regional spectral analyses, a 2D-JMRSI grid was positioned over the central axial slice and shifted in the x and y dimensions to optimally position voxels over regions containing thalamus, temporal lobe, and parieto-occipital cortex. MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity. Other regional analyses did not reveal any significant group differences. The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users. Furthermore, findings suggest that mI and the lThal uniquely contribute to elevated impulsivity.

No MeSH data available.


Related in: MedlinePlus