The Mouse Cortical Interareal Network Reveals Well Defined Connectivity Profiles and an Ultra Dense Cortical Graph

AbstractThe inter-areal wiring pattern of mouse cerebral cortex was analyzed in relation to an accurate parcellation of cortical areas. Twenty-seven retrograde tracer injections were made in 19 areas of a 41 area (plus 7 sub-area) parcellation of the mouse neo-, parahippocampal and perirhinal cortex. Flat mounts of the cortex and multiple histological markers enabled detailed counts of labeled neurons in individual areas. A weight index was determined for each area-to-area pathway based on the Fraction of Extrinsically Labeled Neurons (FLNe). Data analysis allowed cross species comparison with the macaque. Estimation of FLNe statistical variability based on repeat injections revealed high consistency across individuals and justifies using a single injection per area to characterize connectivity. The observed lognormal distribution of connections to each cortical area spanned 5 orders of magnitude and revealed a distinct connectivity profile for each area, analogous to that observed in macaque. The resulting graph has a density of 97% (i.e. 97% of connections that can exist do exist), considerably higher than the 66% density reported for the macaque. Our results provide more sharply defined connectivity profiles and a markedly higher graph density than shown in a recent probabilistic mouse connectome.

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A cross-species comparison: The efficacy of insect repellents and attractants

10.1603/ice.2016.113020 ◽

2016 ◽

Author(s):

Stacy D. Rodriguez

Keyword(s):

Species Comparison ◽

Insect Repellents ◽

Cross Species Comparison

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Cross-species comparison of fluoxetine metabolism with fish liver microsomes

Chemosphere ◽

10.1016/j.chemosphere.2010.01.058 ◽

2010 ◽

Vol 79 (1) ◽

pp. 26-32 ◽

Cited By ~ 40

Author(s):

Emily M. Smith ◽

Shaogang Chu ◽

Gordon Paterson ◽

Chris D. Metcalfe ◽

Joanna Y. Wilson

Keyword(s):

Liver Microsomes ◽

Species Comparison ◽

Fish Liver ◽

Cross Species Comparison

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Serial and parallel processing of tactual information in somatosensory cortex of rhesus monkeys

Journal of Neurophysiology ◽

10.1152/jn.1992.68.2.518 ◽

1992 ◽

Vol 68 (2) ◽

pp. 518-527 ◽

Cited By ~ 124

Author(s):

T. P. Pons ◽

P. E. Garraghty ◽

M. Mishkin

Keyword(s):

Substantial Reduction ◽

Receptive Fields ◽

Somatosensory System ◽

Encounter Rate ◽

Specific Information ◽

Tactile Information ◽

Cortical Areas ◽

Area 3A ◽

Area 3B ◽

Made In

1. Selective ablations of the hand representations in postcentral cortical areas 3a, 3b, 1, and 2 were made in different combinations to determine each area's contribution to the responsivity and modality properties of neurons in the hand representation in SII. 2. Ablations that left intact only the postcentral areas that process predominantly cutaneous inputs (i.e., areas 3b and 1) yielded SII recording sites responsive to cutaneous stimulation and none driven exclusively by high-intensity or "deep" stimulation. Conversely, ablations that left intact only the postcentral areas that process predominantly deep receptor inputs (i.e., areas 3a and 2) yielded mostly SII recording sites that responded exclusively to deep stimulation. 3. Ablations that left intact only area 3a or only area 2 yielded substantial and roughly equal reductions in the number of deep receptive fields in SII. By contrast, ablations that left intact only area 3b or only area 1 yielded unequal reductions in the number of cutaneous receptive fields in SII: a small reduction when area 3b alone was intact but a somewhat larger one when only area 1 was intact. 4. Finally, when the hand representation in area 3b was ablated, leaving areas 3a, 1, and 2 fully intact, there was again a substantial reduction in the encounter rate of cutaneous receptive fields. 5. The partial ablations often led to unresponsive sites in the SII hand representation. In SII representations other than of the hand no such unresponsive sites were found and there were no substantial changes in the ratio of cutaneous to deep receptive fields, indicating that the foregoing results were not due to long-lasting postsurgical depression or effects of anesthesia. 6. The findings indicate that modality-specific information is relayed from postcentral cortical areas to SII along parallel channels, with cutaneous inputs transmitted via areas 3b and 1, and deep inputs via areas 3a and 2. Further, area 3b provides the major source of cutaneous input to SII, directly and perhaps also via area 1. 7. The results are in line with accumulating anatomic and electrophysiologic evidence pointing to an evolutionary shift in the organization of the somatosensory system from the general mammalian plan, in which tactile information is processed in parallel in SI and SII, to a new organization in higher primates in which the processing of tactile information proceeds serially from SI to SII. The presumed functional advantages of this evolutionary shift are unknown.

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