Cortico-cortical relations of cat somatosensory areas SIV and SV.
Sensory cortex is characterized by multiple representations of a given modality which are generally highly interconnected and hierarchically arranged. The cat cerebral cortex contains at least five major areas dedicated to somatosensory processing, yet aside from areas SI and SII, little is known regarding the interconnectivity of the other, higher-level regions, such as SIV and SV. Therefore, this investigation examined the anatomical relationship of somatosensory areas SIV and SV to each other. In adult cats, wheatgerm agglutinin-horseradish peroxidase (WGA-HRP) injected into SIV produced retrogradely labeled neurons in SV in a bilaminar pattern. When biotinylated dextran amine (BDA) was injected into SV, orthogradely labeled axon terminals were found in SIV across all laminae but predominated in supragranular locations. In the reciprocal direction, neurons located in both the supra- and infragranular layers of SIV projected across all laminae of SV, but also in a manner that favored the supragranular layers. Because local inhibitory circuits are critical for specific somatosensory response properties, the distribution of GABA-ergic neurons and their co-localized markers calbindin (CB), calretinin (CR) and parvalbumin (PV) was also compared for SIV and SV using immunocytochemical techniques. Although fundamental differences in laminar arrangement were observed between the different GABA-ergic subtypes, the distribution for each subtype was essentially the same in both SIV and SV. Collectively, these connectional, cytoarchitectonic and organizational similarities indicate that SIV and SV are reciprocally connected and share many somatosensory processing and connectional features.
Clemo
H Ruth
HR
Department of Anatomy and Neurobiology, Medical College of Virginia Campus, Virginia Commonwealth University, 1101 E. Marshall Street, Richmond, VA 23298-0709, USA. rclemo@hsc.vcu.edu
Meredith
M Alex
MA
D000818:Animals; D015415:Biomarkers; D001710:Biotin / Q000031:analogs & derivatives*; D064032:Calbindin 2; D064026:Calbindins; D002415:Cats; D003911:Dextrans; D015335:Molecular Probes; D009434:Neural Pathways; D009474:Neurons / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology* / Q000502:physiology*; D014110:Touch / Q000502:physiology*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D015415:Biomarkers; D064032:Calbindin 2; D064026:Calbindins; D003911:Dextrans; D015335:Molecular Probes; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; C076397:biotinylated dextran amine; D005680:gamma-Aminobutyric Acid; D001710:Biotin