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Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus.

Whissell PD, Cajanding JD, Fogel N, Kim JC - Front Neuroanat (2015)

Bottom Line: However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale.The reverse trend was observed for PV-GABA cells.The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto, Toronto ON, Canada.

ABSTRACT
Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

No MeSH data available.


Related in: MedlinePlus

Abundance of PV-GABA cells in the occipital cortex. (Top) Sections of the occipital cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the occipital cortex. PV-GABA cells are comparatively more numerous in every subregion but the V2mm, where they tended to be more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.
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Figure 5: Abundance of PV-GABA cells in the occipital cortex. (Top) Sections of the occipital cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the occipital cortex. PV-GABA cells are comparatively more numerous in every subregion but the V2mm, where they tended to be more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.

Mentions: Similar to the parietal cortex, the occipital cortex is thought to include large quantities of PV-GABA neurons (∼40%) and low quantities of other GABAergic neurons (Demeulemeester et al., 1988; Hornung et al., 1992; Beaulieu, 1993; del Rio et al., 1994; Gonchar et al., 2007; Xu et al., 2010). However, most prior studies of the occipital cortex have focused on the primary visual cortex (V1) (Hornung et al., 1992; Beaulieu, 1993; del Rio et al., 1994) and have not extensively studied GABAergic cell content in other subregions, such as the secondary visual cortex (V2). In these areas, the relative distribution of GABAergic neurons is less clear. To determine whether the distribution of CCK- and PV-GABA cells varied across the occipital cortex, GFP-labeled cells were measured in the main subdivisions of the primary visual cortex (V1b, V1m) and secondary visual cortex (V2mm, V2ml, and V2l) (Figure 5).


Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus.

Whissell PD, Cajanding JD, Fogel N, Kim JC - Front Neuroanat (2015)

Abundance of PV-GABA cells in the occipital cortex. (Top) Sections of the occipital cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the occipital cortex. PV-GABA cells are comparatively more numerous in every subregion but the V2mm, where they tended to be more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585045&req=5

Figure 5: Abundance of PV-GABA cells in the occipital cortex. (Top) Sections of the occipital cortex from CCK- and PV-Frepe mice. (Bottom) Percentage contribution of CCK- and PV-GABA cells to the total GABA cell population by subregion of the occipital cortex. PV-GABA cells are comparatively more numerous in every subregion but the V2mm, where they tended to be more numerous. Abbreviations: V1b, primary visual cortex, basal region; V1m, primary visual cortex, medial region; V2l, secondary visual cortex, lateral region; V2ml, secondary visual cortex, mediolateral region; V2mm, secondary visual cortex, mediomedial region. Significance at the p < 0.05 level is denoted with an asterisk. Scale bar = 500 μM.
Mentions: Similar to the parietal cortex, the occipital cortex is thought to include large quantities of PV-GABA neurons (∼40%) and low quantities of other GABAergic neurons (Demeulemeester et al., 1988; Hornung et al., 1992; Beaulieu, 1993; del Rio et al., 1994; Gonchar et al., 2007; Xu et al., 2010). However, most prior studies of the occipital cortex have focused on the primary visual cortex (V1) (Hornung et al., 1992; Beaulieu, 1993; del Rio et al., 1994) and have not extensively studied GABAergic cell content in other subregions, such as the secondary visual cortex (V2). In these areas, the relative distribution of GABAergic neurons is less clear. To determine whether the distribution of CCK- and PV-GABA cells varied across the occipital cortex, GFP-labeled cells were measured in the main subdivisions of the primary visual cortex (V1b, V1m) and secondary visual cortex (V2mm, V2ml, and V2l) (Figure 5).

Bottom Line: However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale.The reverse trend was observed for PV-GABA cells.The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto, Toronto ON, Canada.

ABSTRACT
Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

No MeSH data available.


Related in: MedlinePlus