8/31/2011 Authors BioNB 4240 Discussion: Aug. 31, 2011 Carl D Hopkins Carl D. Hopkins Review of Jon H Kaas and Ken Catania’s (2002) Dr. Jon Kaas Kenneth C. Catania , Ph.D. review paper: How do features of sensory Distinguished Centennial Professor of Psychology Professor of Biological Sciences representations develop?. BioEssays 24.4:334 ‐ Associate Professor of Cell and Developmental Stevenson Professor of Biological 343. Biology Sciences Professor of Radiology and Radiological Sciences Dept. Biology Vanderbilt University Vanderbilt University Nashville, Tennessee Jon Kaas Ken Catania • Catania received a BS in zoology from the University of • Education Maryland. In 1992, he received an MS in Neurosciences from • B.A., Northland College, Ashland, Wisconsin, the University of California, San Diego (with Glenn Northcutt), Psychology, 1959 followed in 1994 with a Ph.D. from UCSD. Catania was a post doctoral fellow at Vanderbilt from 1995 ‐ 1997 (with Jon Kaas). ( ) Ph D Psychology Duke University 1965 Ph.D., Psychology, Duke University, 1965 ‐ In 2000 Catania became an assistant professor at Vanderbilt. Thesis Advisor: I.T. Diamond • MacArthur Genius Award (2006) Postdoctoral Fellow, Neurophysiology, University of Wisconsin, 1965 ‐ 1968 ‐ Sponsor: C.N. Woolsey The Journal BioEssays (Jon Wiley and Sons, Inc) [Wiley ‐ Blackwell] IMPACT FACTOR = 4.479 A = the number of times articles published in 2006 and 2007 were cited by indexed journals during 2008. B = the total number of "citable items" published by that journal in 2006 and 2007. ("Citable items" are usually articles, reviews, proceedings, or notes; not editorials or Letters ‐ to ‐ the ‐ Editor.) 2008 impact factor = A / B . • molecular – cellular – biomedical – physiology – translational research – systems ‐ hypotheses encouraged • BioEssays is a review ‐ and ‐ discussion journal publishing novel insights, forward ‐ looking reviews and commentaries in contemporary biology with a molecular, genetic, cellular, or physiological dimension. A further aim is to emphasise transdisciplinarity and integrative biology in the context of organismal studies, systems approaches, through to ecosystems where appropriate. The journal has three main sections: Insights & Perspectives (for ideas, hypotheses and commentaries), Prospects & Overviews (for review ‐ style articles) and Reports & Opinion (for meeting reports, book reviews and letters to the Editor). The Prospects & Overviews section contains mini ‐ reviews highlighting very recent research articles, and longer papers that present a field, its developments and prospects for a broad readership; we also welcome methods papers (including presentation of new model systems) under the rubric Methods, Models & Techniques. The journal's insightful analysis makes it essential reading for professional researchers (from basic research through to medically ‐ related fields), as well as an invaluable tool for lecturers and students. 1
8/31/2011 Mammalian Cortex Two pathways from skin to Cortex In vision, touch, and propioception, and hearing the sensory surface is “mapped” isomorphically onto the brainstem, the Sperry’s Idea: Chemospecificity thalamus, and the cortex. How is order maintained in the maps? Fig. 1 Kaas and Catania (2002) 2
8/31/2011 Hubel and Wiesel: neuron firing determines connections. Experiments with occular dominance columns in cortex. • Sensory areas with activated in synchrony tend to wire up together. • (Experiments with artificial stimulation, or TTX application result in modified sensory maps.) Examples of variation in strict Probably both factors are important: somatotopy in somatosensory cortex chemical gradients + activity patterns. Although some experiments question the importance of activity patterns. • Tree shrew: dorsal trunk maps medial to the For example, applying TTX to cortex during development of sensory map fails to disrupt the barrel cortex map of vibrissae. hindlimb instead of lateral, as in most mammals. Postnatal blockade of cortical activity by tetrodotoxin does not disrupt the • Primates: arm to hand map is reversed in • Primates: arm to hand map is reversed in f formation of vibrissa-related patterns in the rat's somatosensory cortex. ti f ib i l t d tt i th t' t t Chiaia NL, Fish SE, Bauer WR, Bennett-Clarke CA, Rhoades RW. gallago compared to all other primtes. Brain Res Dev Brain Res. 1992 Apr 24;66(2):244-50. PMID: 1318800 [PubMed - indexed for MEDLINE] • S1 cortex maps the “hand” of bats in reverse Related citations order compared to other mammals Modular and Laminar maps are Variation in Retinal Maps variable across species • On and off ganglion cells from retina segregate • Primates: each cortex represents contralateral into different layers in LGN in tree shrews, and hemifield, but many species receive significant different sublayers in cortex ipsilateral hemifield projections. same layers in other mammals. • Large variation in degree of ODCs in mammals Large variation in degree of ODCs in mammals. • Activity patterns may contribute to these • Activity patterns may contribute to these • Modalities mix or segregate in different species: species differences. Platypus: electroreception segregated from tactile senses. Monkeys: segregate RA and SA mechanoreceptors; rats and mice do not. • Thus, it appears that activity dependent development is of variable importance. 3
8/31/2011 Septa appear in maps formed from Star Nose Mole Mechanoreceptors discrete sensory units (whiskers, digits) also projects into a modular map in S1 • Star nose mole • Scanning EM of one half • Scanning EM of one half Cytochrome oxidase levels Barrel Cortex of star high (activity) low (low activity) • S1 cortex. Cytochrome oxidase stain. Septa occur in the S2 map of the Septa occur only in sensory maps with forepaw of the mole disruptions of sensory surface • between pads on paw • Star nose mole forepaw • between hand and face when juxtaposed • CO activity in S2 • between lips, teeth, tongue • in LGN where optic disk disrupts retina • Septa also occur in visual system between discorrelated receptor types: e.g. laminae in LGN representing differing cell types (Parvo ‐ cellular, magnocellular and contra ‐ versus ipsilateral eye) • Septa are absent in auditory cortex which receives continuously varying tonotopic input from cochlea. In rare cases of extra Siamese cats have nearly completely sensory lobes; extra crossed optic nerves (complete modules exist in decussation), unlike normal cats which brainstem, thalamus, and have partial decussation. cortex. In turn, the contralateral projection of Correlated activity induces A1 is inverted, maintaining continuity module in three sensory with the normal projection of the structures. ipsilateral retina. Likely that activity patterns determine the orientation of the inverted map. 4
8/31/2011 New optical methods reveal feature specific substructure within each barrel related to the direction of vibrissa motion, which Conclusion appears only in adults. Suggests also that activity dependent information influences the map structure in the adult. 1) gradients of signaling molecules produced in sensory Yves Kremer, Jean ‐ François Léger, Dan Goodman, Romain Brette, and Laurent surfaces appear to be important in establishing crude Bourdieu. (2011) Late Emergence of the Vibrissa Direction Selectivity Map in the maps of sensory surfaces in the brain. Rat Barrel Cortex. The Journal of Neuroscience, July 20, 2011 • 31(29):10689 – 10700 • 10689 2) Information received from the receptor sheet seems to control the fine structure of the maps modular control the fine structure of the maps – modular elements. 3) Evidence comes from experimental manipulations of sensory surfaces (additional whisker or lobe of star) alters map devepopment. 4) Variation in map structure across species appears to be largely determined by activity patterns. 5
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