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Response of frog retina ganglion cells to moving monochromatic spots under photopic conditions
0042.6919 XI I 11617.O4W2.00 0 Pergamon Prey Ltd
101620. 1981 Rcrronlr Vol. 21.pp.1617 Vision Prmtcd I” Great Bnlaln
RESPONSE OF FROG RETINA GANGLION CELLS TO MOVING MONOCHROMATIC SPOTS UNDER PHOTOPIC CONDITIONS URSULA GR&SER-CORNEHLS
Freie Universitlt
and
RAMSEY
McD.
SAUNDERS
Berlin, Department of Physiology, Arnimallee 22, 1000 Berlin 33, Germany
INTRODUflION
Stimuhtion
When the spectral responsiveness of the frog (Rana esculenta) retina neurons is determined using a black spot (“black hole”) moving on a monochromatic background of mesopic luminance levels, several subclasses of the 4 “classical” neuron types (Maturana et al., 1960; Griisser and Griisser-Cornehls, 1976) became distinguishable (Griisser-Cornehls and Saunders, 1975. 1976. 1978, 1981). Under mesopic adaptation, classes 1 and 2 neurons exhibited two subclasses: one, the a-type, had a broad spectral response curve and appeared to receive excitatory inputs from all receptor types found in the frog retina (green and red rods, single cones, double cones), the other sub-class-the b-typxhibited response maxima at 450 and 580nm. It seems to receive inputs from the green rods and the single cones (absorption maximum of green rods 433 nm; of single cones 578 nm). In addition to these subclasses, we found in class 3 neurons a third subclass-the c-type-xhibiting a more selective spectral response curve with a single maximum at 500 nm. This subclass (c) appears to receive excitatory inputs mainly from the red rods (absorption-maximum of red rods: 502 nm). The purpose of the experiments described in this work was to determine, whether the spectral response types are also found with photopic stimulus conditions. Monochromatic photopic light stimuli were moved across an achromatic grey background through the receptive field of the respective neurons. Hereby the spectral responsiveness of the excitatory receptive field (ERF) was tested. METHODS
Successful experiments were performed on 30 medium-sized adult frogs. The animals were anesthetized with ethyl-m-aminobenzoate (MS 222 Sandoz), the skull above the optic tedtum was removed, the dura opened and the brain covered with mineral oil. Each animal was immobilized by a lymphatic sac injection of 0.50.8 mg D-tubocurarine chloride, then covered with moist gauze and placed on a moist sponge with its head fixed in the center of a perimeter.
Light from a 450 Watt Xenon lamp (Heinzinger TNX 450, ozon-free) is collected by a condenser, passed through a water filter 7 cm thick to remove the infrared radiation, then focussed by a 150mm lens onto the slit of a monochromator. To ensure spectral purity of the output signals, the monochromator is provided with special colour filters. The output is sent through a fiber optic beam splitter (Schott), thereby producing two identical output signals. One signal is sent to the moving stage in the stimulating region of a special purpose perimeter (Griisser and Dannenberg, 1965), the other to a photomultiplier (RCA 4832). The first signal provided a bright uniform spot of monochromatic light, which could be moved at different velocities by an electronically controlled motor across the window of the perimeter. The diameter of the spot was IOmm and subtended approx. 2.2 deg of visual angle at the frog’s eye. The output from the photomultiplier was first amplified and then sent to an automatic slit control unit. Since the photomultiplier has a flat spectral sensitivity curve in the region 4OO-i’OOnm, it functions essentially as a non-selective photodetector, i.e. it measures the energy independent of the wavelength. The feedback loop to the monochromator slit controls its output and ensures that-as the wavelength is varied-the monochromator is adjusted automatically, providing equal quantum energy at all wavelengths. Recordings
Tungsten microelectrodes with electrolytically platinized tips of l-3 pm in diameter were used to record impulses of the agerent optic nerve fibers in the superficial layers of the optic tectum. The action potentials of the single neurons were amplified by a Tektronix 122 amplifier and a 2A61 plug-in-unit of a Tektronix 565 oscilloscope. All signals were stored on tape (Bell and Howell, 3A3200). Photographic recordings were taken with a Tonnies Recordine camera. From the data the frequency of the neuronal impulses was calculated and for statistical treatment a Lint-8 digital computer was used.
1617
1618
URSULA GR~ER-CORNEHLS
and RAMSEYMCD.SAWDERS
Fig. I. Block diagram of stimulus equipment. *Present experiments
RESULlS
The neuronal spectral subclasses Class 1 neurons. Figure 2 shows typical results found in class 1 neurons. Two “chromatic” subclasses of class I neurons were distinguish~. the a-type which had a broad spectral response curve and the b-type which had two maxima, one at 433 nm, the other at 580nm. The broad spectral response type probably receives inputs from all receptor types of the frog’s retina, while the tp with the two maxima receives inputs from the green rods and the single cones only. Class 2 neurons. Class 2 neurons are highly movement sensitive, respond only to small contrast stimuli (4deg). This was also the case for monochromatic
stimuli. The responses to stationary light stimuli (light on-off) were weak. fast adapting or absent (Maturana rr ul.. 1960; Griisser and Griisser-Cornehls. 1976). Figure 3 shows the spectral response curves of class 2 neurons. Two subgroups were found. a broad spectral response type or a-type. and a response type with two maxima or b-type. The maxima of the b-type neurons were either blue dominant or red dominant. Class 3 nrurons. Figure 4 shows the spectral response curves of class 3 neurons. In class 3 neurons we have not yet found the chromatic response type a. i.e. neurons with broad spectral response curves. In Fig. 4a and b the chromatic b,-type and b,-type, exhibiting two maxima, one at 433 nm and one at 58Onm are displayed. The maxima of the b-type neurons could he either blue dominant (b,) or red dominant
Fig. 2. The spectralre&nse curves of the two types of class 1 neurons. Ordinate: average impulse frequency (imp.sec-‘) during movement of the chromatic stimulus across the ERF; abscissa: wavelength (nm), vertical bars: SD. Angular velocity 9.2 deg. set- ‘--also for Figs 3. 4 and 5.
Response of retina ganglion cells to monochromatic
1619
0
m
loo
spots
SW
Warelength
pm]
Fig. 3. Spectral response curves of 3 chromatic types of class 2 neurons.
3 class - 3 bl -mums
(b)
o’
,
400
a 500
-laolh
,
MO
fml
Yh alcngth
do Pm1
A0
O’ad -lenpth
@I
Fig. 4. The spectral response curves of 3 types of class 3 neurons.
(b,). In addition to the b-types, a c-type neuron (Fig. 4c) with a maximum at 500 nm was founfd.
Hyla septentnonalrs Class-l-neuron
Movement and directional sensitivity Some neurons besides being movement sensitive also provided clear evidence of directional selectivity depending on the chromatic input. No directional selectivity, however, was found in these neurons with achromatic black-white stimuli. Figure 5 shows spectral response curves of a class l* neuron in the cuban treefrog Hyla septentionalis, which exhibited a clear a-type behaviour, i.e. broad spectral response curve to stimulus movements from right to left. For movement from left to right, however, a neuronal activation was found only at wavelengths between 540 and 64Onm, i.e. in a range of the spectrum corresponding to the single cone maximum sensitivity. The same neurons were also found in Rana. In Fig. 6 the spectral responsiveness of another directional sensitive neuron is shown. It was a class 3 neuron examined with horizontally moving chromatic stimuli. Different angular velocities were applied. For
Wavelength bm]
Fig. 5. The spectral response curves of a class I* neuron of Hyla septentrionalis. Responses obtained by movement horizontally to the left (“to-movement”) and to the right (“fro-movement”).
URSULAGR~~SSER-CORNEHLS and RAMSEY McD. SAurVotas
1620
Class-3-rleunxl
Class-3-neuron
L
9.2o.s-1
1J
1
0.5
5.0
50
Velocity(ckqs-0
OJ,_,
700
Wavelength @miJ Fig. 6. Spectral response curves of a class 3 neuron obtained with different angular velocities of the moving monochromatic spot (2.3 deg.=‘; 4.6 deg.sec-’ and 9.2 deg’sec- I). Horizontal movement to the left.
Fig. 7. Velocity response functions of a class 3a neuron at wavelength of 580, 433 and 5OOnm. Impulse rate (impulses.se-‘) are displayed along the ordinate and the stimulus velocities (degrees’sec- ‘) along the abscissa.
In other neurons the spectral response characteristic was dependent on the velocity of the moving monochromatic stimuli. These findings might be explained by narrow spectral or antagonistic chromatic response properties of the unidirectional signal flow in part of the amacrine cells. The findings of Griisser-Cornehls and Saunders (1975, 1976) were confirmed: the exponent of the velocity function of frog retinal ganglion cells was greater when the responses were triggered by cone signals as compared to responses triggered by red and green rod signals. ERF.
movements from left to right the neuron always responded according to the b-type (not shown in Fig. 6). For movement from the right to the left (Fig. 6). however, the b-type spectral response curve was found only at a velocity of 9.2 deg *sex- ‘. At lower velocities (4.6 deg. set - ’ and 2.3 deg. set- ‘) no responses were observed with stimuli in the short wavelength region of the spectrum. Strong responses appeared with stimuli in the far red region of the spectrum (single cones excitation).
Ackno&dyemenr-The project WdS supported by a grant from the Deutsche Forschungsgemeinschaft (Gr 276).
Velocityjimctions Figure 7 shows the velocity functions of a class 3a neuron (broad spectral response curve) measured with monochromatic stimuli of 433, 500 and 580 nm moving with different velocities across the ERF. A steeper slope of the velocity function was observed with SgOnm stimuli as compared to the slope obtained with 433 and 5OOnm stimuli. SUMMARY
AND COMMENTS
In summary one can say that the same three “chromatic” subclasses of the frog retinal ganglion cells. which were found using a black spot moving across a monochromatic background field under mesopic conditions, were also present when photopic monochromatic light spots were moved across the ERF of the ganglion cells (photopic adaptation level). In some neurons the directional sensitivity depended on and was interrelated with the chromatic responses. The chromatic response type of these neurons was dependent on the direction in which the monochromatic light spot was moving ~~~06s the
REFERENCES Griisser O.-J. and Dannenberg H. (1965) Eine PerimeterApparatur zur Reizung mit bewegten visuellen Mustern. Pjliigers Archs 28!$ 373-378. Griisser O.-J. and Griisser-Cornehls U. (1976) Physiology of the anuran visual system. In Neurobiology o/ tke Fray (Edited by Llinb R. and Recht W.). Springer, Berlin. Griisser-Cornehls U. and Saunders R.McD. (1975) The spectral properties of class I, 2. 3 and 4 neurons of the frog’s optic tectum. Pj7iigcrs Archs, Suppl. 359, R 101. Griisser-Cornehls U. and Saunders R.McD. (1976) Responses of class I, 2 and 3 neurons of the frog retina td moving colour contrasts. Pfliigers Archs, Suppl. 365, R 46. Griisser-Cornehls U. and Saunders RMcD. (1978) A chromaticity diagram and theories for colour processing in the frox. Pf?i&rs Archs 373. R 79. Griisser-Cor&ls U. and S&ders R.McD. (1981) Chromatic subclnsaes of frog retinal ganglion cells: studies using black stimuli moving on a monochromatic background. Vision Res. 21, d-478. Maturana H. R., Lettvin J. Y.. McCulloch W. S. and Pitts W. H. (1960) Anatomy and physidogy of vision in the frog. J. yen. Physlol. 43. 129-175.
101620. 1981 Rcrronlr Vol. 21.pp.1617 Vision Prmtcd I” Great Bnlaln
RESPONSE OF FROG RETINA GANGLION CELLS TO MOVING MONOCHROMATIC SPOTS UNDER PHOTOPIC CONDITIONS URSULA GR&SER-CORNEHLS
Freie Universitlt
and
RAMSEY
McD.
SAUNDERS
Berlin, Department of Physiology, Arnimallee 22, 1000 Berlin 33, Germany
INTRODUflION
Stimuhtion
When the spectral responsiveness of the frog (Rana esculenta) retina neurons is determined using a black spot (“black hole”) moving on a monochromatic background of mesopic luminance levels, several subclasses of the 4 “classical” neuron types (Maturana et al., 1960; Griisser and Griisser-Cornehls, 1976) became distinguishable (Griisser-Cornehls and Saunders, 1975. 1976. 1978, 1981). Under mesopic adaptation, classes 1 and 2 neurons exhibited two subclasses: one, the a-type, had a broad spectral response curve and appeared to receive excitatory inputs from all receptor types found in the frog retina (green and red rods, single cones, double cones), the other sub-class-the b-typxhibited response maxima at 450 and 580nm. It seems to receive inputs from the green rods and the single cones (absorption maximum of green rods 433 nm; of single cones 578 nm). In addition to these subclasses, we found in class 3 neurons a third subclass-the c-type-xhibiting a more selective spectral response curve with a single maximum at 500 nm. This subclass (c) appears to receive excitatory inputs mainly from the red rods (absorption-maximum of red rods: 502 nm). The purpose of the experiments described in this work was to determine, whether the spectral response types are also found with photopic stimulus conditions. Monochromatic photopic light stimuli were moved across an achromatic grey background through the receptive field of the respective neurons. Hereby the spectral responsiveness of the excitatory receptive field (ERF) was tested. METHODS
Successful experiments were performed on 30 medium-sized adult frogs. The animals were anesthetized with ethyl-m-aminobenzoate (MS 222 Sandoz), the skull above the optic tedtum was removed, the dura opened and the brain covered with mineral oil. Each animal was immobilized by a lymphatic sac injection of 0.50.8 mg D-tubocurarine chloride, then covered with moist gauze and placed on a moist sponge with its head fixed in the center of a perimeter.
Light from a 450 Watt Xenon lamp (Heinzinger TNX 450, ozon-free) is collected by a condenser, passed through a water filter 7 cm thick to remove the infrared radiation, then focussed by a 150mm lens onto the slit of a monochromator. To ensure spectral purity of the output signals, the monochromator is provided with special colour filters. The output is sent through a fiber optic beam splitter (Schott), thereby producing two identical output signals. One signal is sent to the moving stage in the stimulating region of a special purpose perimeter (Griisser and Dannenberg, 1965), the other to a photomultiplier (RCA 4832). The first signal provided a bright uniform spot of monochromatic light, which could be moved at different velocities by an electronically controlled motor across the window of the perimeter. The diameter of the spot was IOmm and subtended approx. 2.2 deg of visual angle at the frog’s eye. The output from the photomultiplier was first amplified and then sent to an automatic slit control unit. Since the photomultiplier has a flat spectral sensitivity curve in the region 4OO-i’OOnm, it functions essentially as a non-selective photodetector, i.e. it measures the energy independent of the wavelength. The feedback loop to the monochromator slit controls its output and ensures that-as the wavelength is varied-the monochromator is adjusted automatically, providing equal quantum energy at all wavelengths. Recordings
Tungsten microelectrodes with electrolytically platinized tips of l-3 pm in diameter were used to record impulses of the agerent optic nerve fibers in the superficial layers of the optic tectum. The action potentials of the single neurons were amplified by a Tektronix 122 amplifier and a 2A61 plug-in-unit of a Tektronix 565 oscilloscope. All signals were stored on tape (Bell and Howell, 3A3200). Photographic recordings were taken with a Tonnies Recordine camera. From the data the frequency of the neuronal impulses was calculated and for statistical treatment a Lint-8 digital computer was used.
1617
1618
URSULA GR~ER-CORNEHLS
and RAMSEYMCD.SAWDERS
Fig. I. Block diagram of stimulus equipment. *Present experiments
RESULlS
The neuronal spectral subclasses Class 1 neurons. Figure 2 shows typical results found in class 1 neurons. Two “chromatic” subclasses of class I neurons were distinguish~. the a-type which had a broad spectral response curve and the b-type which had two maxima, one at 433 nm, the other at 580nm. The broad spectral response type probably receives inputs from all receptor types of the frog’s retina, while the tp with the two maxima receives inputs from the green rods and the single cones only. Class 2 neurons. Class 2 neurons are highly movement sensitive, respond only to small contrast stimuli (4deg). This was also the case for monochromatic
stimuli. The responses to stationary light stimuli (light on-off) were weak. fast adapting or absent (Maturana rr ul.. 1960; Griisser and Griisser-Cornehls. 1976). Figure 3 shows the spectral response curves of class 2 neurons. Two subgroups were found. a broad spectral response type or a-type. and a response type with two maxima or b-type. The maxima of the b-type neurons were either blue dominant or red dominant. Class 3 nrurons. Figure 4 shows the spectral response curves of class 3 neurons. In class 3 neurons we have not yet found the chromatic response type a. i.e. neurons with broad spectral response curves. In Fig. 4a and b the chromatic b,-type and b,-type, exhibiting two maxima, one at 433 nm and one at 58Onm are displayed. The maxima of the b-type neurons could he either blue dominant (b,) or red dominant
Fig. 2. The spectralre&nse curves of the two types of class 1 neurons. Ordinate: average impulse frequency (imp.sec-‘) during movement of the chromatic stimulus across the ERF; abscissa: wavelength (nm), vertical bars: SD. Angular velocity 9.2 deg. set- ‘--also for Figs 3. 4 and 5.
Response of retina ganglion cells to monochromatic
1619
0
m
loo
spots
SW
Warelength
pm]
Fig. 3. Spectral response curves of 3 chromatic types of class 2 neurons.
3 class - 3 bl -mums
(b)
o’
,
400
a 500
-laolh
,
MO
fml
Yh alcngth
do Pm1
A0
O’ad -lenpth
@I
Fig. 4. The spectral response curves of 3 types of class 3 neurons.
(b,). In addition to the b-types, a c-type neuron (Fig. 4c) with a maximum at 500 nm was founfd.
Hyla septentnonalrs Class-l-neuron
Movement and directional sensitivity Some neurons besides being movement sensitive also provided clear evidence of directional selectivity depending on the chromatic input. No directional selectivity, however, was found in these neurons with achromatic black-white stimuli. Figure 5 shows spectral response curves of a class l* neuron in the cuban treefrog Hyla septentionalis, which exhibited a clear a-type behaviour, i.e. broad spectral response curve to stimulus movements from right to left. For movement from left to right, however, a neuronal activation was found only at wavelengths between 540 and 64Onm, i.e. in a range of the spectrum corresponding to the single cone maximum sensitivity. The same neurons were also found in Rana. In Fig. 6 the spectral responsiveness of another directional sensitive neuron is shown. It was a class 3 neuron examined with horizontally moving chromatic stimuli. Different angular velocities were applied. For
Wavelength bm]
Fig. 5. The spectral response curves of a class I* neuron of Hyla septentrionalis. Responses obtained by movement horizontally to the left (“to-movement”) and to the right (“fro-movement”).
URSULAGR~~SSER-CORNEHLS and RAMSEY McD. SAurVotas
1620
Class-3-rleunxl
Class-3-neuron
L
9.2o.s-1
1J
1
0.5
5.0
50
Velocity(ckqs-0
OJ,_,
700
Wavelength @miJ Fig. 6. Spectral response curves of a class 3 neuron obtained with different angular velocities of the moving monochromatic spot (2.3 deg.=‘; 4.6 deg.sec-’ and 9.2 deg’sec- I). Horizontal movement to the left.
Fig. 7. Velocity response functions of a class 3a neuron at wavelength of 580, 433 and 5OOnm. Impulse rate (impulses.se-‘) are displayed along the ordinate and the stimulus velocities (degrees’sec- ‘) along the abscissa.
In other neurons the spectral response characteristic was dependent on the velocity of the moving monochromatic stimuli. These findings might be explained by narrow spectral or antagonistic chromatic response properties of the unidirectional signal flow in part of the amacrine cells. The findings of Griisser-Cornehls and Saunders (1975, 1976) were confirmed: the exponent of the velocity function of frog retinal ganglion cells was greater when the responses were triggered by cone signals as compared to responses triggered by red and green rod signals. ERF.
movements from left to right the neuron always responded according to the b-type (not shown in Fig. 6). For movement from the right to the left (Fig. 6). however, the b-type spectral response curve was found only at a velocity of 9.2 deg *sex- ‘. At lower velocities (4.6 deg. set - ’ and 2.3 deg. set- ‘) no responses were observed with stimuli in the short wavelength region of the spectrum. Strong responses appeared with stimuli in the far red region of the spectrum (single cones excitation).
Ackno&dyemenr-The project WdS supported by a grant from the Deutsche Forschungsgemeinschaft (Gr 276).
Velocityjimctions Figure 7 shows the velocity functions of a class 3a neuron (broad spectral response curve) measured with monochromatic stimuli of 433, 500 and 580 nm moving with different velocities across the ERF. A steeper slope of the velocity function was observed with SgOnm stimuli as compared to the slope obtained with 433 and 5OOnm stimuli. SUMMARY
AND COMMENTS
In summary one can say that the same three “chromatic” subclasses of the frog retinal ganglion cells. which were found using a black spot moving across a monochromatic background field under mesopic conditions, were also present when photopic monochromatic light spots were moved across the ERF of the ganglion cells (photopic adaptation level). In some neurons the directional sensitivity depended on and was interrelated with the chromatic responses. The chromatic response type of these neurons was dependent on the direction in which the monochromatic light spot was moving ~~~06s the
REFERENCES Griisser O.-J. and Dannenberg H. (1965) Eine PerimeterApparatur zur Reizung mit bewegten visuellen Mustern. Pjliigers Archs 28!$ 373-378. Griisser O.-J. and Griisser-Cornehls U. (1976) Physiology of the anuran visual system. In Neurobiology o/ tke Fray (Edited by Llinb R. and Recht W.). Springer, Berlin. Griisser-Cornehls U. and Saunders R.McD. (1975) The spectral properties of class I, 2. 3 and 4 neurons of the frog’s optic tectum. Pj7iigcrs Archs, Suppl. 359, R 101. Griisser-Cornehls U. and Saunders R.McD. (1976) Responses of class I, 2 and 3 neurons of the frog retina td moving colour contrasts. Pfliigers Archs, Suppl. 365, R 46. Griisser-Cornehls U. and Saunders RMcD. (1978) A chromaticity diagram and theories for colour processing in the frox. Pf?i&rs Archs 373. R 79. Griisser-Cor&ls U. and S&ders R.McD. (1981) Chromatic subclnsaes of frog retinal ganglion cells: studies using black stimuli moving on a monochromatic background. Vision Res. 21, d-478. Maturana H. R., Lettvin J. Y.. McCulloch W. S. and Pitts W. H. (1960) Anatomy and physidogy of vision in the frog. J. yen. Physlol. 43. 129-175.