VISION LABORATORY

Paul R. Martin

The work of this laboratory concerns the neurophysiological substrates of visual perception.

RESEARCH in 1993

Retinal ganglion cell morphology in a New World primate

The retinogeniculate pathway in Old World primates is comprised mainly of two classes of ganglion cells - midget and parasol cells - which project, respectively, to the parvo- and magno-cellular layers of the lateral geniculate nucleus. They are hypothesized to be the anatomical substrates of the chromatic and luminance processing channels. In collaboration with Ann Sefton studies were carried out on a New World monkey, to establish whether these cell pathways are common to all primates. In 1993 Ann Goodchild and Krishna Ghosh found cells which resembled midget and parasol cells in the New World marmoset monkey Callithrix Jacchus. Group A cells in marmoset resembled parasol cells in Old World monkeys. Group B cells in marmoset had practically identical morphology to midget ganglion cells near the fovea. Outside the central retina, the dendritic field size of B cells increased, but like midget cells they had the smallest dendritic fields at any retinal location. The results suggested that the two main classes of ganglion cells and their associated pathways were a conserved feature of the primate visual system.

Sampling properties of ganglion cell and photoreceptor arrays

Another important feature of Old World primate vision is the exquisite spatial resolving power of the central retina. This depends on a high spatial density of cone photoreceptors and ganglion cells near the fovea. In collaboration with Ulrike Grünert from the Max Planck Institute for Brain Research in Germany, Heath Wilder measured the spatial density of these cells in the marmoset Callithrix jacchus. This showed that this New World species has the retinal substrates required for high resolution spatial vision, and that the sampling density of ganglion cells in the marmoset fovea is high enough to transmit faithfully the spatial information from the cone array by separate (presumed ON- and OFF-) populations of ganglion cells.

RESEARCH PLANNED for 1994

In the next stage of the project the Laboratory plans to record extracellular responses from relay cells in the lateral geniculate nucleus, and thus identify animals as dichromatic or trichromatic, as well as study the changes that trichromacy confers on the spatial and temporal properties of cells in the visual pathway. Retinas from these animals will be examined for possible morphological differences in ganglion cells, and will also be used for immunochemical and ultrastructural studies.

Figure goes here

Top panel: Spatial density of cells in the ganglion cell layer near the fovea of the marmoset retina. Peak cell density near 60,000 cells/mm2 is seen within 1 mm of the fovea. Different symbols show results from different animals. Bottom panel: Dentritic field diameter of group A and group B ganglion cells in the temporal retina (data pooled from four animals). Note that group B cells have very small (midget-like) dendritic fields near the fovea, and are smaller than group A cells at all retinal eccentricities.

PERSONNEL in 1993 and 1994

Dr Paul R. Martin	Lecturer (in-charge)		University	1991-
Dr Ann Goodchild	NHMRC Research Officer		NHMRC		1993-
Christine Lucas		Laboratory Assistant (1/5)	NHMRC		1993
Ludwik Kowalski		Programmer (2/5)		NHMRC		1993
Krishna Ghosh		BSc(Hons) student 				1993
			PhD student					1994-
Heath Wilder		BSc(Hons) student 				1993
			MSc student					1994-
Tricia Chan		BSc(Hons) student		 		1993
Current effective full-time personnel = 5.3

COLLABORATIONS

Colour responses and resolution of macaque ganglion cells: Dr Trichur R. Vidyasagar, Australian National University (1992-present).

Anatomical substrates of colour vision: Dr Ulrike Grünert and Prof. Heinz Wässle, Max Planck Institute for Brain Research, Frankfurt am Main, Germany (1992-present).

Luminance and chromatic contrast sensitivity in the marmoset lateral geniculate nucleus: Prof. Barry Lee, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany (1993-present).

FACILITIES

The Laboratory is located in room 419 of the Anderson Stuart Building. It has all of the electrophysiological equipment required for recording and analyzing single cell activity in the visual system: life support apparatus, stereotaxic headholder, micro-drives, fundus camera, projector- and video-based visual stimulators, two-channel recording system for action potentials, Macintosh computers for data acquisition and analysis, micro-electrode-making equipment and Zeiss FSM fixed stage microscope for injecting single cells in fixed or living tissue.

FUNDING in 1993 and 1994

NHMRC		The visual system in 		Martin PR 	1993	$73,862
		dichromatic and trichromatic 	Sefton AJ	1994 	$61,334
		marmoset monkeys				1995

Ramaciotti	Anatomical substrates of 	Martin PR 	1994	$26,373
		colour vision in primates 	Sefton AJ.
	i
Total for 1993: $73,862

Total for 1994: $87,707

TEACHING in 1993

BMedSc: Human Life Sciences 2 Tutorials;: 1 follow-up tutorial on gastrointestinal physiology. ???is this all? Dentistry 2 Lectures: 18: 12, on neurophysiology and 6 new lectures on gastrointestinal physiology (taught in conjunction with Science 2 Auxilliary and Science 2). Tutorials: 3: 2 on neurophysiology and 1 on gastrointestinal physiology (in conjunction with Science 2 Auxilliary and Science 2). Repeated? no. times? Quizzes: 3 on lecture material, using sample examination questions (in conjunction with Science 2 Auxilliary and Science 2). Practical classes: 4, each of 3 h, on reflexes and cutaneous sensation. Examination: by multiple choice and short essay questions. Medicine 2 Lecture: 1, in distinction course, on vision. Practical classes: 1, of 3 h, repeated?, on vision/ophthalmoscope. Science 2 Lectures: 18: 12 on neurophysiology and 6 new lectures on gastrointestinal physiology (given concurrently with Science 2 Auxilliary and Dentistry 2). Tutorials: 3: 2 on neurophysiology, 1 on gastrointestinal physiology (combined with Science 2 Auxilliary and Dentistry 2). Repeated? no. times? Quiz: 3 on lecture material, using sample examination questions (combined with Science 2 Auxilliary and Dentistry 2). Practical classes: 1, of 3 h, repeated 4 times?, on cutaneous sensation, reflexes and vision/ophthalmoscope. Examination: multiple choice and short essay questions. Science 2 Auxiliary Lectures: 18: 12 on neurophysiology and 6 new lectures on gastrointestinal physiology (given concurrently with Science 2 and Dentistry 2). Tutorials: 3: 2 on neurophysiology and 1 on gastrointestinal physiology (given concurrently with Science 2 and Dentistry 2). Quizzes: 3 on lecture material, using sample examination questions (given concurrently with Science 2 and Dentistry 2). Examination: multiple choice and short essay questions. Science 3/BMedSc (Neuroscience and Advanced Neuroscience) Lectures: 9, on neurophysiology of vision, including 3 new lectures on the neural basis of visual cognition. Practical classes: 2, each of 3 h, repeated, involving computer-based teaching of image processing and psychophysical testing of visual function. Examination: short essay question. Discussion sessions 5, each of 1.5 h, in which students presented papers from the scientific literature. Advanced Neuroscience Discussion sessions: 7, each of 2 h, in which students present and discuss papers from the scientific literature. Total distribution (hours of formal teaching) HLS2 Dent2 Med2 Sc2 Sc3/BMedSc ScAux Total Lectures – 18* 1 18* 12 18* 31 Practicals (no.) – 12(4) 6(2) 12(4) 12(2) – 42 Tutorials 1 6* – 6* 22 6* 29 *Lectures to Sci2, SciAux and Dent2 were given concurrently. Total formal contact teaching time = 102 h Time was also spent on lecture preparation, setting and marking exams and essays and answering student queries. OTHER ACTIVITIES in 1993 Service to the department Assistant course organizer, Advanced Neuroscience (Integrative and Molecular) course offered to BMedSc and Sci3. Conference organizer Assistant Local Secretary for the Australian Neuroscience Society Meeting held in Sydney in Feb 1994. Invited lectures In Australia: Univ. of N.S.W. (Apr) Overseas: Dept Psychology, Univ. of California at Los Angeles (May) Max Planck Institute for Brain Research, Frankfurt, Germany (Dec) International Conference attended Association for Research in Vision and Ophthalmology, Sarasota, U.S.A. (May) Visiting Fellowship Visiting fellow at the John Curtin School of Medical Research, Australian National University, Canberra. (Month?) Service to the N.S.W. Institute of Psychiatry Lecturer for Psychiatrists-in-training course (June) Service to the Save Sight Institute Lecturer for Ophthalmology basic science course (June) Refereeing Manuscripts: for Visual Neuroscience (1) Grant applications: for ARC (1) THESES PASSED in 1993 BSc(Hons) Ghosh K (1993) The morphology of retinal ganglion cells in the marmoset monkey. (Result: 1st class; awarded Colin Dunlop prize) Wilder H (1993) Photoreceptor and ganglion cell topography in the marmoset monkey. (Result: 2nd class, division 1) 5-YEAR RESEARCH PUBLICATIONS (Appointed in 1991; publications prior to 1991 arose from work at the Max Planck Institute, Germany.) JOURNAL ARTICLES 1989 Lee BB, Martin PR, Valberg A (1989) Sensitivity of macaque retinal ganglion cells to chromatic and luminance flicker. Journal of Physiology, 414, 223-243 Lee BB, Martin PR, Valberg A (1989) Amplitude and phase of responses of macaque retinal ganglion cells to flickering stimuli. Journal of Physiology, 414, 245-263 1990 Kaiser, PK, Lee BB, Martin PR, Valberg A (1990) The physiological basis of the minimally distinct border demonstrated in the ganglion cells of the macaque retina. Journal of Physiology, 422, 153-183 Lee BB, Pokorny J, Smith VC, Martin PR, Valberg A (1990) Luminance and chromatic modulation sensitivity of macaque ganglion cells and human observers. Journal of the Optical Society of America, 7, 2223-2236 1991 Grünert U, Martin PR (1991) Rod bipolar cells in the macaque monkey retina: Immunoreactivity and connectivity. Journal of Neuroscience, 11, 2742-2758 1992 Martin PR, Grünert U (1992) Spatial density and immunoreactivity of bipolar cells in the macaque monkey retina. Journal of Comparative Neurology, 323, 269-287 Smith VC, Pokorny J, Martin PR, Valberg A, Lee BB (1992) Responses of macaque ganglion cells to the relative phase of heterochromatically modulated lights. Journal of Physiology, 458, 191-221 1993 Lee BB, Martin PR, Valberg A, Kremers J (1993) Physiological mechanisms underlying psychophysical sensitivity to combined luminance and chromatic modulation. Journal of the Optical Society of America A, 10, 1403-1412 Early 1994 Wässle H, Grünert U, Martin PR, Boycott BB (1994) Immunocytochemical characterization and spatial distribution of midget bipolar cells in the macaque monkey retina. Vision Research, 34, 561-579 CHAPTERS IN BOOKS Martin PR, Grünert U (1991) Density of bipolar cells in the macaque monkey retina. From Pigments to Perception: Advances in Understanding Visual Processes. Valberg A, Lee BB, eds, NATO Advanced Science, Institute Series A, Plenum, London, 73-78 Wässle H, Grünert U, Martin PR, Boycott BB (1994) Color coding in the primate retina: predictions and constraints from anatomy. Structural and Functional Organization of the Neocortex. A Symposium in the Memory of Otto D. Creutzfeldt, Albowitz B, Kuhnt U, Nothdurft HC, Wahle P, Springer, Berlin, Heidelberg, New York, (in press) CONFERENCE ABSTRACT AND PRESENTATION in 1993 Martin PR, Grünert U, Wässle H (1993) Spatial density of midget bipolar cells in the macaque monkey retina. Investigative Ophthalmology and Visual Science (ARVO abstracts), 34, 986 State name of conference, city, country, month 1993 PHYSIOLOGY REPORT - MARTIN VISION LABORATORY

Paul R. Martin

RESEARCH in 1993

Retinal ganglion cell morphology in a New World primate

Sampling properties of ganglion cell and photoreceptor arrays

RESEARCH PLANNED for 1994

PERSONNEL in 1993 and 1994

COLLABORATIONS

FACILITIES

FUNDING in 1993 and 1994

Total for 1993:

Total for 1994:

SCHOLARSHIPS in 1993 ans 1994 .... ? e.g.

TEACHING in 1993

BMedSc: Human Life Sciences 2

Dentistry 2

Medicine 2

Science 2

Science 2 Auxiliary

Science 3/BMedSc

Total distribution

HLS2 Dent2 Med2 Sc2 Sc3/BMedSc ScAux Total

OTHER ACTIVITIES in 1993

Service to the department

Conference organizer

Invited lectures

International Conference attended

Visiting Fellowship

Service to the N.S.W. Institute of Psychiatry

Service to the Save Sight Institute

Refereeing

THESES PASSED in 1993

BSc(Hons)

5-YEAR RESEARCH PUBLICATIONS

JOURNAL ARTICLES

1989

1990

1991

1992

1993

Early 1994

CHAPTERS IN BOOKS

CONFERENCE ABSTRACT AND PRESENTATION in 1993