bluuebunny/crossref_metadata_2025 huggingface dataset:
Natural resource use, crop damage and attitudes of rural people in the vicinity of the Maputo Elephant Reserve, Mozambique
Authors: DE BOER WILLEM F. , BAQUETE DULCINEIA S.
Published: July 2002

Participation by local communities in management is widely considered a means of sustaining protected areas. In parts of the world with a history of armed conflict, the chances of such an approach being successfully adopted might seem remote. One such area is the Maputo Elephant Reserve in southern Mozambique. The aim was to improve understanding of the local people's use of natural resources and perceptions of the Reserve's impact. Interviews and questionnaires distributed in four different villages were used to estimate the relative value of these resources in relation to the attitude of the local people towards the Reserve. The people gave a relative value rank for each specific use of each plant, animal and fish resource. On average 60% of the households exploited more than two different resource categories. The plant resources of the Reserve were used by 71% of the households and were valued more highly than animal and fish resources. Plants were used for many purposes; construction material, fuelwood and fruits had the highest relative values. Antelopes, hippopotamus and elephants were valued highest amongst a range of animal species which were hunted by 21% of households. Amongst uses of animals, consumption, use of the skins and commercial sale of the meat were especially important. When asked if they liked the Reserve, 88% of respondents answered positively. The attitude towards the Reserve was correlated with crop damage experiences; people with crop damage caused by elephants, hippos or bushpigs, were more negative. Attitude of respondents was inversely related to the number of species invading their agricultural fields. Resource use intensity, use purpose, resource value and attitude were different amongst sites and dependent on site-specific circumstances, different management strategies could be necessary for the four sites. A resource management plan should be drawn up, local people should be included in the management team and steps should be taken to improve the relationship between the Reserve's authorities and the local population generally.
Conflicting attitudes towards elephants around the Budongo Forest Reserve, Uganda
Authors: HILL CATHERINE M.
Published: July 2002

Attitudes of local people to wildlife, and particularly to large animals, are an increasingly important element of conservation work, but attitudes may vary within a community according to gender, and prior experience of wildlife. Data were collected by questionnaire and informal interviews with 59 men and 57 women living on the southern edge of the Budongo Forest Reserve, Uganda, to assess the influence of these factors in attitudes towards elephants, in an area from which they are now absent, and to conservation in general. It was hypothesized that prior experience of elephants might influence people's perceptions of them, and that this in turn might influence their attitudes towards the issue of elephant conservation. The results of this study did not generally support this. There was no evidence that people with prior experience of elephants were any more likely to support their conservation than were people who did not have prior experience of them. Within this community men and women expressed very different views as to the behaviour of elephants. Women were more likely than men to report that elephants were dangerous, irrespective of whether they had seen an elephant or not. Locally, conservation was considered to be particularly important and beneficial as a strategy because it 'should help ensure protection of people and their crops from marauding elephants and other animals'. Attitudes to, and expectations of, conservation as a strategy also varied between members of this community with respect to gender, but age and ethnic group were not good predictors of whether people were likely to be supportive of conservation issues or not.
The impact of wildlife-related benefits on the conservation attitudes of local people around the Selous Game Reserve, Tanzania
Authors: GILLINGHAM SARAH , LEE PHYLLIS C.
Published: July 2002

In recent years there has been a proliferation of projects aiming to integrate human development needs with conservation objectives, and to establish mutually beneficial relationships for the management of natural resources between rural communities and the state. This paper presents data from a case study of human-wildlife interactions in villages along the northern boundary of the Selous Game Reserve in south-east Tanzania. Since 1989, this area has been the site of a project working to promote community wildlife management (CWM). Questionnaire survey data were used to examine villagers' conservation attitudes towards wildlife, the Game Reserve, and the activities of the CWM project and state wildlife management authority. Despite local support for the conservation of wildlife, many respondents were either unaware or held negative views of the activities of the wildlife management institutions. Logistic regression analyses show that while access to game meat from the CWM project has had a positive influence on perceptions of wildlife benefits and awareness of the project's activities, it has had no significant effect on local perceptions of the Game Reserve and the activities of the state wildlife management authority. The factors underlying the observed pattern of conservation attitudes were identified as the inequitable distribution of benefits from the CWM project, and the limited nature of community participation in wildlife management. The importance of institutional issues for the future progress of participatory approaches to conservation with development is emphasized.
Biodiversity as an environmental service in Brazil's Amazonian forests: risks, value and conservation
Authors: FEARNSIDE PHILIP M.
Published: July 2002

The environmental service provided by the great biodiversity of Amazonian forests is one of several factors leading to the conclusion that much greater efforts are warranted to reduce the destruction of these forests. Risks to biodiversity in Amazonian forests include deforestation, logging, fires, fragmentation, depletion of fauna, invasion by exotic species, and climate change. Financial values assigned to biodiversity depend strongly on the purposes of valuation. Utilitarian benefits include the values of presently-marketed and presently-unexploited forest products, and the monetary value of environmental benefits. Non-monetary values of Amazonian forests are also essential components of decision-making on conservation. Measures of ‘willingness to pay’ and ‘willingness to accept’ can be useful as indicators of potential financial flows, but should not be confused with the true values of the forests to society. Valuation for the purpose of setting penalties for destruction of biodiversity is an important legal question in Brazil and must take into consideration additional factors.

Conservation of biodiversity in Brazil includes creation of various types of protected areas. The status of these areas varies greatly, with practice frequently deviating from official requirements. Creating reserves that include human occupants has a variety of pros and cons. Although the effect of humans is not always benign, much larger areas can be brought under protection regimes if human occupants are included. Additional considerations apply to buffer zones around protected areas. The choice and design of reserves depends on the financial costs and biodiversity benefits of different strategies. In Brazil, rapid creation of lightly-protected ‘paper parks’ has been a means of keeping ahead of the advance of barriers to establishment of new conservation units, but emphasis must eventually shift to better protection of existing reserves. Indigenous peoples have the best record of maintaining forest, but negotiation with these peoples is essential in order to ensure maintenance of the large areas of forest they inhabit. The benefits of environmental services provided by the forest must accrue to those who maintain these forests. Development of mechanisms to capture the value of these services will be a key factor affecting the long-term prospects of Amazonian forests. However, many effective measures to discourage deforestation could be taken immediately through government action, including levying and collecting taxes that discourage land speculation, changing land tenure establishment procedures so as not to reward deforestation, revoking remaining incentives, restricting road building and improvement, strengthening requirements for environmental impact statements (RIMAs) for proposed development projects, and creating employment alternatives.
Survey of life-cycle measures and metrics for concurrent
product and process design
Authors: PRASAD BIREN
Published: July 2002

Concurrent Engineering needs a series of measures
(or measurement criteria) that are distinct to each process,
and a set of metrics to check (and validate) the outcome
when two or more of the life-cycle processes are overlapped
or required to be executed in parallel. Because product
realization involves concurrent processes that occur across
multiple disciplines and organizations, appropriate measures
and the methods of qualifying metrics are essential. Inevitably,
such concurrent processes generate design conflicts among
multiple life-cycle concerns. Individual assurances of
satisfying life-cycle design criterion (one at a time)
do not capture the most important aspect of Concurrent
Engineering—the system perspective—meaning
achieving a well-balanced trade-off among the different
life-cycle design measures. While satisfying life-cycle
design measures in a serial manner only those, which are
not in conflict, are occasionally met. The paper first
describes a set of life-cycle measures and metrics and
explains how those could be used for gaining operational
excellence. Second, this paper provides an insight into
the mechanisms (such as knowledge-based systems, rule-based
simulation, and rule-based optimization) to ensure an effective
trade-off across different life-cycle measures, customer
requirements, and their inclusion into a product design,
development, and delivery (PD3) process.
Diagnosability evaluation of systems using bipartite graph and matrix
approach
Authors: WANI M.F. , GANDHI O.P.
Published: July 2002

This paper presents a methodology for assessment
of diagnosability of mechanical and hydraulic systems.
The method is developed on the basis of relationships between
system performance parameters and physical objects, that
is, components of the system. These relationships are identified
by system functional domain and are modeled in terms of
a bipartite graph, called Diagnosability Bipartite Graph
(DBG). A matrix called Diagnosability Matrix (DM) represents
the DBG. Various diagnosability parameters of the system
are derived from the DBG and the DM and these are useful
in evaluation and comparison of design variants of the
system. These parameters: are maximum number of set conflicts
(MNS), maximum number of components in a set conflict (MNCS),
diagnosability effort and cost (DEC), and average merit
of diagnosability (AMD). The design having the lowest value
of MNCS, AMD, and DEC; and highest value of MNS has the
highest diagnosability. On the basis of these, a best design
alternative is selected from diagnosability point of view.
Moreover, components, which have poor diagnosability, are
also identified. Maximum number of set conflicts (MNS)
also guides in system fault diagnosis. The proposed procedure
aids in the design and development of maintainable systems
from diagnosability consideration. The method can also
be used for evaluating and comparing the diagnosability
of the systems. This method is illustrated with the help
of two examples.
Enabling principles of concurrency and simultaneity in concurrent
engineering
Authors: PRASAD BIREN
Published: July 2002

The paper describes a set of seven fundamental
principles for achieving “best concurrency and simultaneity.”
The concurrent approach is gaining worldwide attention
at this moment. The paralleling of life-cycle activities
and process restructuring are being deemed necessary by
more and more industries. An automobile product development
process example is used in this paper to illustrate many
aspects of these seven principles. The principles help
the concurrent teams, first, to define how to decompose
the product, process and work activities and then, how
to arrange these decomposed activities so that “best
concurrency and simultaneity” can be achieved.
Paracoccidioidomycosis in Colombia: an ecological study
Authors: CALLE D. , ROSERO D. S. , OROZCO L. C. , CAMARGO D. , CASTAÑEDA E. , RESTREPO A.
Published: July 2002

The natural habitat of Paracoccidioides brasiliensis, agent of paracoccidioidomycosis (PCM), remains unknown. This study is aimed at establishing associations between the ecological variables present in all Colombian municipalities and the incidence of PCM. Records of 940 patients were studied and several ecological variables analysed, as well as their association to amount of patients per total rural population in each municipality, determined through a multivariate analysis. All 940 patients came from 216 municipalities (20·3 %), out of which, 93 were birthplace and place of long-term residence for 121 patients. The Incidence Rate Ratio (IRR) was determined for these 93 municipalities. The following variables fitted the model: altitude from 1000 to 1499 metres above sea level (IRR = 6·37), rainfall from 2000 to 2999 mm (IRR = 2·15), presence of humid forests (Holdridge) (IRR = 1·79) and coffee (IRR = 1·95), tobacco (IRR = 3·59) crops. These results indicate that these municipalities constitute reservareas for P. brasiliensis (Borelli).
Analysis of the host-specific haemagglutination of influenza

A(H1N1) viruses isolated in the 1995/6 season
Authors: MORISHITA T. , NOBUSAWA E. , LUO S. , SATO K. , NAKAJIMA S. , NAKAJIMA K.
Published: July 2002

Two phenotypes of human influenza A(H1N1) virus are currently

circulating in Japan. One

(group 1) agglutinates both chicken and goose red blood cells (CRBC and
GRBC),

the other (group 2) agglutinates GRBC but not CRBC. In the 1995/6 season,
group

2 viruses accounted

for 70% of the H1N1 viruses isolated in MDCK cells. The 1995/6 viruses

were located on two

branches of the genetic tree. One branch contained both group 1 and group

2 viruses and the

other branch contained only group 2 viruses. Group 2 viruses had aspartic

acid at residue 225

in the haemagglutinin (HA) protein, the key amino acid residue for group

2 phenotype. The

HA protein of group 1 viruses had a change from aspartic acid to asparagine

at residue 225

and the expressed HA protein of these viruses adsorbed CRBC. Serial

passage of group 2

viruses in MDCK cells or embryonated chicken eggs caused these viruses
to

gain the ability to

agglutinate CRBC. MDCK-adapted viruses had the same amino acid sequences
of HA

polypeptide as the original ones, but egg-adapted viruses had changed

amino acid sequences.

The expressed HA protein from one egg-adapted virus that originally

belonged to group 2 adsorbed CRBC.
Epidemiology and properties of heat-stable enterotoxin-producing
Escherichia coli serotype O169[ratio ]H41
Authors: NISHIKAWA Y. , HELANDER A. , OGASAWARA J. , MOYER N. P. , HANAOKA M. , HASE A. , YASUKAWA A.
Published: July 2002

Enterotoxigenic Escherichia coli (ETEC) serotype O169[ratio ]H41
organisms have become the most
prevalent ETEC in Japan since the first outbreak in 1991. It was assumed
that the outbreaks
were due to clonal spread of this new ETEC serotype. The relationship of
32 strains isolated
from 6 outbreaks were examined for biotype, antibiotic susceptibility,
enterotoxigenicity,
protein banding pattern, lipopolysaccharide banding pattern, plasmid analysis,
and ribotyping.
Further, the strains were examined by haemagglutination, surface hydrophobicity,
and the
ability to adhere to HEp-2 cells. The present study suggests that the outbreaks
were caused by
multiple clones of STp-producing O169[ratio ]H41 since they showed differences
in ribotype and
outer membrane protein banding patterns. The strains did not agglutinate
human or bovine
red blood cells in a mannose-resistant manner. They adhered to HEp-2 cells
in a manner
resembling enteroaggregative E. coli. Five strains were examined
by dot-blot tests for the
colonization factor antigens CFA/I, CS1, CS2, CS3, CS4, CS5, CS6, CS7,
PCFO159,
PCFO166 and CFA/III. Although four strains expressed CS6, no structure
for CS6 was
identified. A strain that the anti-CS6 MAbs did not react with could adhere
to HEp-2 cells in
mannose resistant manner; thus, it is unlikely that CS6 play an important
role in the adhesion
to the cells. Electron microscopy studies of the O169[ratio ]H41 strains
suggested that curly fimbriae,
a possible new colonization factor, may be playing an important role in
the adhesion of the
bacteria to HEp-2 cells. In conclusion, outbreaks due to ETEC O169: H41
were caused by
multiple clones, and the strains should be examined in detail for a possible
new colonization
factor.
Investigation of the 1994–5 Ukrainian Vibrio cholerae

epidemic using molecular methods
Authors: CLARK C. G. , KRAVETZ A. N. , DENDY C. , WANG G. , TYLER K. D. , JOHNSON W. M.
Published: July 2002

Thirty-seven Vibrio cholerae and four non-cholera
Vibrio isolates from Ukraine, including
strains from the epidemic of 1994–5, were analysed by molecular methods.
Results from PFGE
and ribotyping indicated that all Ukrainian toxigenic
V. cholerae were closely related to each
other and to an isolate from a patient from Pakistan. A non-toxigenic river
water strain
obtained during the height of the epidemic was more distantly
related to these V. cholerae
strains, while the Vibrio parahaemolyticus isolates
and Vibrio alginolyticus isolate were not
closely related to V. cholerae or each other.
ERIC- and REP-PCR allowed the differentiation
of strains identical by other methods. The results obtained confirm that
the epidemic Ukrainian
strains are most closely related to seventh pandemic strains from Asia
and support a
hypothesis that the Ukrainian epidemic of 1994–5 was caused by toxigenic
environmental
strains surviving since the time of the 1991 Ukrainian epidemic or before.
The NMDAR1 subunit of the N-methyl-D-aspartate receptor
is localized at postsynaptic sites opposite both retinal
and cortical terminals in the cat superior colliculus
Authors: MIZE R. RANNEY , BUTLER GRACE D.
Published: July 2002

The N-methyl-D-aspartate receptor (NMDAR) is an ionotropic
glutamate receptor that is important in neurotransmission
as well as in processes of synaptic plasticity in the mammalian
superior colliculus (SC). Despite the importance of this
receptor in synaptic transmission, there is as yet no evidence
that demonstrates directly the synaptic localization of
the NMDAR receptor in SC. We have used electron-microscope
(EM) immunocytochemistry to localize the NMDAR1 subunit
of this receptor protein and its association with sensory
afferents in the cat SC. Retinal synaptic terminals were
identified by normal morphology and cortical synaptic terminals
by degeneration after lesions of areas 17–18 of the
visual cortex. At the light-microscope level, label was
densest within the superficial gray and upper optic layers,
but also present in all other layers. Label was contained
within cell bodies, dendrites, and a few putative axons.
At the EM level, antibody labeling was found along postsynaptic
densifications and internalized within the cytoplasm of
a variety of dendrites and some cell bodies. Postsynaptic
profiles labeled by NMDAR1 included conventional dendrites
and presynaptic dendrites which contained pleomorphic synaptic
vesicles and are known to be GABAergic. Many of the labeled
postsynaptic densifications of both of these profile types
received synaptic inputs from retinal or cortical terminals.
Virtually no NMDAR1 immunoreactivity was found on thin
dendritic thorns or putative spines, even when these were
postsynaptic to retinal or cortical terminals. In summary,
these results show that the NMDAR1 subunit is postsynaptic
to both retinal and cortical afferents, which are known
to be glutamatergic, and are consistent with physiological
evidence showing that stimulation of either pathway can
activate the NMDA receptor.
AMPA-selective glutamate receptor subunits GluR2 and GluR4
in the cat retina: An immunocytochemical study
Authors: QIN PU , POURCHO ROBERTA G.
Published: July 2002

(article appeared in Visual Neuroscience (1999),
16, 1105–1114.)

Due to an oversight, Table 2 that appeared on p. 1106
of Visual Neuroscience 16:6 had errors in the
body of the Table. A corrected version of Table 2 is
printed below.

Cambridge University Press and the authors regret any
inconvenience that this inadvertent error may have caused.
Differential induction of gene expression by basic fibroblast
growth factor and neuroD in cultured retinal pigment
epithelial cells
Authors: YAN RUN-TAO , WANG SHU-ZHEN
Published: July 2002

Embryonic chick retinal pigment epithelial (RPE)
cells can undergo transdifferentiation upon appropriate
stimulation. For example, basic fibroblast growth factor
(bFGF) induces intact RPE tissue younger than embryonic
day 4.5 (E4.5) to transdifferentiate into a neural retina.
NeuroD, a gene encoding a basic helix-loop–helix
transcription factor, triggers de novo production
of cells that resemble young photoreceptor cells morphologically
and express general neuron markers (HNK-1/N-CAM and MAP2)
and a photoreceptor-specific marker (visinin)
from cell cultures of dissociated E6 RPE (Yan & Wang,
1998). The present study examined whether bFGF will lead
to the same transdifferentiation phenomenon as neuroD
when applied to dissociated, cultured E6 RPE cells, and
whether interplay exists between the two factors under
the culture conditions. Dissociated E6 RPE cells were cultured
in the presence or absence of bFGF, and with or without
the addition of retrovirus expressing neuroD.
Gene expression was analyzed with immunocytochemistry and
in situ hybridization. Unlike neuroD,
bFGF did not induce the expression of visinin,
or HNK-1/N-CAM and MAP2. However, bFGF elicited the expression
of RA4 immunogenicity; yet, many of these RA4-positive
cells lacked a neuronal morphology. Addition of bFGF to
neuroD-expressing cultures did not alter the number
of visinin-expressing cells; misexpression of
neuroD in bFGF-treated cultures did not change
the number of RA4-positive cells, suggesting the absence
of interference or synergistic interaction between the
two factors. Our data indicated that bFGF and neuroD
induced the expression of different genes in cultured RPE
cells.
Response variability and information transfer in directional
neurons of the mammalian horizontal optokinetic system
Authors: CLIFFORD COLIN W.G. , IBBOTSON MICHAEL R.
Published: July 2002

This study is concerned with how information about
the direction of visual motion is encoded by motion-sensitive
neurons. Motion-sensitive neurons are usually studied using
stimuli unchanging in speed and direction over several
seconds. Recently, it has been suggested that neuronal
responses to more naturalistic stimuli cannot be understood
on the basis of experiments with constant-motion stimuli
(de Ruyter van Steveninck et al., 1997). We measured the
variability and information content of spike trains recorded
from directional neurons in the nucleus of the optic tract
(NOT) of the wallaby, Macropus eugenii, in response
to constant and time-varying motion. While the NOT forms
part of the mammalian optokinetic system, we have shown
previously that the responses of its directional neurons
resemble those of insect H1 in many respects (Ibbotson
et al., 1994). We find that directional neurons in the
wallaby NOT respond with lower variability and higher rates
of information transmission to time-varying stimuli than
to constant motion. The difference in response variability
is predicted by an inhomogeneous Poisson model of neuronal
spiking incorporating an absolute refractory period of
2 ms during which no subsequent spike can be fired. Refractoriness
imposes structure on the spike train, reducing variability
(de Ruyter van Steveninck & Bialek, 1988; Berry &
Meister, 1998). A given refractory period has a greater
impact when firing rates are high, as for the responses
of NOT neurons to time-varying stimuli. It is in just these
cases that variability in experimentally observed spike
trains is lowest. Thus, differences in response variability
do not necessarily imply that different models are required
to predict neuronal responses to constant- and time-varying
motion stimuli.
Response profiles to texture border patterns in area V1
Authors: NOTHDURFT HANS-CHRISTOPH , GALLANT JACK L. , VAN ESSEN DAVID C.
Published: July 2002

Cells in area V1 of the anesthetized macaque monkey
were stimulated with large texture patterns composed of
homogeneous regions of line elements (texels) with different
orientations. To human observers, such patterns appear
to segregate, with the percept of sharp boundaries between
texture regions. Our objective was to investigate whether
the boundaries are reflected in the responses of single
cells in V1. We measured responses to individual texels
at different distances from the texture border. For each
cell, patterns of optimally or orthogonally orientated
texels were adjusted so that only one texel fell into the
receptive field and all other texels fell in the visually
unresponsive regions outside. In 37 out of 156 neurons
tested (24%), texels immediately adjacent to a texture
border evoked reliably larger responses than identical
texels farther away from the border. In 17 neurons (11%),
responses to texels near the border were relatively reduced.
Border enhancement effects were generally stronger than
border attenuation effects. When tested with four different
border configurations (two global orientations and two
edge polarities), many cells showed reliable effects for
only one or two configurations, consistent with cells encoding
information about the orientation of the texture border
or its location with respect to the segmented region. Across
the sample, enhancement effects were similar for all texture
borders. Modulation by the texture surround was predominantly
suppressive; even the responses near texture borders were
smaller than those to a single line. We compared these
results with the results of a popout test in which the
line in the receptive field was surrounded by homogeneous
texture fields either orthogonal or parallel to the center
line. The patterns of response modulation and the temporal
onset of differential responses were similar in the two
tests, suggesting that the two perceptual phenomena are
mediated by similar neural mechanisms.
Neuronal and microglial response in the retina of streptozotocin-induced
diabetic rats
Authors: ZENG XIAO-XIA , NG YEE-KONG , LING ENG-ANG
Published: July 2002

This study reports Müller cell and neuronal
changes and microglial reaction in streptozotocin-induced
diabetic rats. Glial fibrillary acidic protein (GFAP) immunoreactivity
was largely confined to astrocytes in the nerve fiber layer
(NFL) and ganglion cell layer (GCL) in control rats. In
diabetic rats especially those killed after 12 months,
GFAP immunostaining could be traced along the entire length
of Müller cell processes, extending from the inner
to the outer limiting membrane. With the antibody neuronal
nuclei, immunopositive cells were located in the GCL and
the inner part of the inner nuclear layer (INL) in both
diabetic and age-matched control rats. In diabetic rats,
labelled cells were reduced in both layers being more marked
in the INL. In age-matched control rats, OX42-immunoreactive
microglial cells were distributed mainly in the NFL and
GCL; some cells were localized in the inner plexiform layer,
but rarely in the outer plexiform layer (OPL). Beginning
1 month after diabetes, the microglial cells appeared hypertrophic.
Furthermore, microglial number as estimated from cell counts
in different layers of the retina was significantly increased,
with the occurrence of some cells in the OPL at 4 months.
At 14 and 16 months, reactive microglial cells were detected
in the outer nuclear layer and photoreceptor layer. Present
results suggest that microglial reaction in induced diabetes
was elicited by neuronal cell loss in both GCL and INL
as well as by some pathologic changes affecting the photoreceptors.
Rapid identification of ocular dominance columns in macaques
using cytochrome oxidase, Zif268, and dark-field microscopy
Authors: HORTON JONATHAN C. , HOCKING DAVINA R. , ADAMS DANIEL L.
Published: July 2002

Strabismus induces an abnormal pattern of alternating
light and dark columns of cytochrome oxidase (CO) activity
in macaque striate cortex. This pattern may arise because
visual perception is suppressed in one eye to avoid diplopia.
To test whether CO activity is reduced in the ocular dominance
columns of the suppressed eye, we performed monocular enucleation
to co-label the ocular dominance columns with Zif268 immunohistochemistry
in seven exotropic adult Macaca fascicularis.
This approach was unsuccessful, for two reasons. First,
Zif268 yielded inconsistent labelling, that was usually
greater in the enucleated eye's ocular dominance columns,
but was sometimes greater in the intact eye's columns.
Therefore, Zif268 was not a reliable method for identifying
the ocular dominance columns serving each eye. Second,
in three control animals we found that a brief survival
period following monocular enucleation (needed for Zif268
levels to change) was long enough to alter CO staining.
For example, a survival time of only 3 h was sufficient
to induce CO columns, indicating that the activity of this
enzyme fluctuates more rapidly than realized previously.
Independent of these findings, we have also discovered
that acute monocular enucleation produces a vivid pattern
of ocular dominance columns visible in unstained or CO-stained
sections under dark-field illumination. The ocular dominance
columns of the acutely enucleated eye appear dark. This
was verified by labelling the ocular dominance columns
with [3H]proline. Dark-field illumination
of the cortex after acute monocular enucleation offers
a new, easy method for identifying the ocular dominance
columns in macaques.
In search of the visual pigment template
Authors: GOVARDOVSKII VICTOR I. , FYHRQUIST NANNA , REUTER TOM , KUZMIN DMITRY G. , DONNER KRISTIAN
Published: July 2002

Absorbance spectra were recorded by microspectrophotometry
from 39 different rod and cone types representing amphibians,
reptiles, and fishes, with A1- or A2-based visual pigments
and λmax ranging from 357 to 620 nm. The
purpose was to investigate accuracy limits of putative
universal templates for visual pigment absorbance spectra,
and if possible to amend the templates to overcome the
limitations. It was found that (1) the absorbance spectrum
of frog rhodopsin extract very precisely parallels that
of rod outer segments from the same individual, with only
a slight hypsochromic shift in λmax, hence
templates based on extracts are valid for absorbance in
situ; (2) a template based on the bovine rhodopsin
extract data of Partridge and De Grip (1991) describes
the absorbance of amphibian rod outer segments excellently,
contrary to recent electrophysiological results; (3) the
λmax/λ invariance of spectral shape
fails for A1 pigments with small λmax and
for A2 pigments with large λmax, but the
deviations are systematic and can be readily incorporated
into, for example, the Lamb (1995) template. We thus propose
modified templates for the main “α-band”
of A1 and A2 pigments and show that these describe both
absorbance and spectral sensitivities of photoreceptors
over the whole range of λmax. Subtraction
of the α-band from the full absorbance spectrum leaves
a “β-band” described by a λmax-dependent
Gaussian. We conclude that the idea of universal templates
(one for A1- and one for A2-based visual pigments) remains
valid and useful at the present level of accuracy of data
on photoreceptor absorbance and sensitivity. The sum of
our expressions for the α- and β-band gives a good
description for visual pigment spectra with λmax
> 350 nm.
Projections of the superior colliculus to subdivisions of
the inferior pulvinar in New World and Old World monkeys
Authors: STEPNIEWSKA IWONA , QI HUI-XIN , KAAS JON H.
Published: July 2002

Patterns of terminals labeled after WGA-HRP injections
in the superior colliculus (SC) in squirrel monkeys and
macaque monkeys, and after DiI application in marmosets,
were related to the architecture of the pulvinar and dorsal
lateral geniculate nucleus (LGN). In all studied species,
the SC projects densely to two architectonic subdivisions
of the inferior pulvinar, the posterior inferior pulvinar
nucleus (PIp) and central medial inferior pulvinar nucleus
(PIcm). These projection zones expressed substance
P. Thus, sections processed for substance P reveal SC termination
zones in the inferior pulvinar. The medial subdivision
of the inferior pulvinar, PIm, which is known to project
to visual area MT, does not receive a significant collicular
input. Injections in MT of a squirrel monkey revealed no
overlap between SC terminals and neurons projecting to
area MT. Thus, PIm is not the significant relay station
of visual input from the SC to MT. The SC also sends an
input to the LGN, however, this projection is sparser than
the input directed to pulvinar.
Brian B. Boycott
Authors: Wässle Heinz
Published: July 2002

This issue of Visual Neuroscience contains
the last scientific contribution of Brian B. Boycott. In
December 1999, Brian was just recovering from a serious
operation in London, when I sent him an early draft of
the paper. He returned the manuscript with many excellent
suggestions for improvements and in the accompanying letter
he wrote, “I think you are generous to include my
name. I won't argue because when it comes out in 2000
it will be the 50th anniversary of my first published paper.
This appeals to me.” Unfortunately Brian did not
live to see the publication of this paper and passed away
on April 22, 2000.
Contributions of cat posterior parietal cortex to visuospatial
discrimination
Authors: LOMBER STEPHEN G. , PAYNE BERTRAM R.
Published: July 2002

The purpose of the present study was to examine the contributions
made by cat posterior parietal cortex to the analyses of
the relative position of objects in visual space. Two cats
were trained on a landmark task in which they learned to
report the position of a landmark object relative to a
right or left food-reward chamber. Subsequently, three
pairs of cooling loops were implanted bilaterally in contact
with visuoparietal cortices forming the crown of the middle
suprasylvian gyrus (MSg; architectonic area 7) and the
banks of the posterior-middle suprasylvian sulcus (pMS
sulcal cortex) and in contact with the ventral-posterior
suprasylvian (vPS) region of visuotemporal cortex. Bilateral
deactivation of pMS sulcal cortex resulted in a profound
impairment for all six tested positions of the landmark,
yet bilateral deactivation of neither area 7 nor vPS cortex
yielded any deficits. In control tasks (visual orienting
and object discrimination), there was no evidence for any
degree of attentional blindness or impairment of form discrimination
during bilateral deactivation of pMS cortex. Therefore,
we conclude that bilateral cooling of pMS cortex, but neither
area 7 nor vPS cortex, induces a specific deficit in spatial
localization as examined with the landmark task. These
observations have significant bearing on our understanding
of visuospatial processing in cat, monkey, and human cortices.
Spectral-tuning mechanisms of marine mammal rhodopsins and
correlations with foraging depth
Authors: FASICK JEFFRY I. , ROBINSON PHYLLIS R.
Published: July 2002

It has been observed that deep-foraging marine mammals
have visual pigments that are blue shifted in terms of
their wavelength of maximal absorbance (λmax)
when compared to analogous pigments from terrestrial mammals.
The mechanisms underlying the spectral tuning of two of
these blue-shifted pigments have recently been elucidated
and depend on three amino acid substitutions (83Asn,
292Ser, and 299Ser) in dolphin rhodopsin,
but only one amino acid substitution (308Ser)
in the dolphin long-wavelength-sensitive pigment. The objective
of this study was to investigate the molecular basis for
changes in the spectral sensitivity of rod visual pigments
from seven distantly related marine mammals. The results
show a relationship between blue-shifted rhodopsins (λmax
≤ 490 nm), deep-diving foraging behavior, and the substitutions
83Asn and 292Ser. Species that forage
primarily near the surface in coastal habitats have a rhodopsin
with a λmax similar to that of terrestrial
mammals (500 nm) and possess the substitutions 83Asp
and 292Ala, identical to rhodopsins from terrestrial
mammals.
Spatial summation and center-surround antagonism in the
receptive field of single units in the dorsal lateral geniculate
nucleus of cat: Comparison with retinal input
Authors: RUKSENAS O. , FJELD I.T. , HEGGELUND P.
Published: July 2002

Spatial summation and degree of center-surround antagonism
were examined in the receptive field of nonlagged cells
in the dorsal lateral geniculate nucleus (dLGN). We recorded
responses to stationary light or dark circular spots that
were stepwise varied in width. The spots were centered
on the receptive field. For a sample of nonlagged X-cells,
we made simultaneous recordings of action potentials and
S-potentials, and could thereby compare spatial summation
in the dLGN cell and in the retinal input to the cell.
Plots of response versus spot diameter showed
that the response for a dLGN cell was consistently below
the response in the retinal input at all spot sizes. There
was a marked increase of antagonism at the retinogeniculate
relay. The difference between the retinal input and dLGN
cell response suggested that the direct retinal input to
a relay cell is counteracted in dLGN by an inhibitory field
that has an antagonistic center-surround organization.
The inhibitory field seems to have the same center sign
(ON- or OFF-center), but a wider receptive-field center
than the direct retinal input to the relay cell. The broader
center of the inhibitory field can explain the increased
center-surround antagonism at the retinogeniculate relay.
The ratio between the response of a dLGN cell and its retinal
input (transfer ratio) varied with spot width. This variation
did not necessarily reflect a nonlinearity at the retinogeniculate
relay. Plots of dLGN cell response against retinal input
were piecewise linear, suggesting that both excitatory
and inhibitory transmission in dLGN are close to linear.
The variation in transfer ratio could be explained by sustained
suppression evoked by the background stimulation, because
such suppression has relatively stronger effect on the
response to a spot evoking weak response than to a spot
evoking a strong response. A simple model for the spatial
receptive-field organization of nonlagged X-cells, that
is consistent with our findings, is presented.
The feedforward component in depolarizing red responses
of R/G horizontal cells in carp retina
Authors: HU JIAN-FENG , LIANG PEI-JI
Published: July 2002

Light responses of R/G chromaticity-type horizontal cells
(R/G HCs) and luminosity-type horizontal cells (LHCs) were
intracellularly recorded in isolated superfused carp retina,
and the response dynamics analyzed. The results revealed
that (1) No significant difference in delay was detected
between R/G HC red and green responses; (2) The rising
speed was quicker for R/G HC depolarizing red responses
compared to that of its hyperpolarizing green responses;
and (3) Dynamic characteristics of R/G HC red responses
and its changes caused by green background illumination
did not follow that of LHC red response. All these results
suggest that the depolarizing response of the R/G HCs cannot
be entirely mediated by the negative feedback pathway from
LHCs onto cones. A direct inhibitory input from red cones
to R/G HCs may exist.
Two-frequency analysis of interactions elicited by Vernier stimuli
Authors: VICTOR JONATHAN D. , CONTE MARY M.
Published: July 2002

In five subjects, we measured visual evoked potentials
(VEPs) elicited by Vernier targets in which the contrast
of the two components of the stimuli were modulated by
sinusoids at distinct frequencies f1
and f2. This approach allows for the
extraction of VEP signatures of spatial interactions, namely,
responses at intermodulation frequencies n1f1 + n2f2,
without the need to introduce motion into the stimulus. The most
prominent interactions were at the sum frequency f1
+ f2, and, for frequency pairs that were sufficiently
separated, the difference frequency f1 −
f2. These responses had a systematic dependence
on the temporal parameters of the stimulus, corresponding to an
effective latency of 145 to 165 ms. Fourth-order interactions were also
detected, particularly at the frequencies 2f1 ±
2f2. These VEP signatures of interaction were similar
to interactions seen for colinear line segments separated by a gap. Thus,
for Vernier stimuli devoid of motion, VEP signatures of interaction are
readily detected but are not specific to hyperacuity displacements. The
distribution of interactions across harmonic orders is consistent with
local rectification preceding the spatial interactions. Their effective
latencies and dependence on spatial parameters are consistent with
interactions within V1 receptive fields or mediated by horizontal
connections between cells with a similar orientation tuning within V1.
Neural interactions between cone photoreceptors and horizontal
cells in the turtle (Mauremys caspica) retina
Authors: ASI HUSAM , PERLMAN IDO
Published: July 2002

Horizontal cells and cone photoreceptors in the
vertebrate retina are interconnected by a complex network
of synapses leading to the generation of color-coded responses
in chromaticity horizontal cells. A simple cascade model
of excitatory feedforward and inhibitory feedback synapses
had been suggested to underlie these observations. In this
study, the photoresponses of cones and horizontal cells
were recorded intracellularly from the turtle eyecup. Three
different approaches were adopted in order to test quantitatively
the cascade model. Comparing linearity functions between
these neurons indicated multiple excitatory inputs to each
type of horizontal cells. The depolarizing photoresponses
of R/G C-type horizontal cells were considerably faster
than those of L-type horizontal cells but slower than those
recorded from L-cones. This observation disagrees with
the basic assumption of the cascade model that assign the
depolarizing photoresponses of R/G C-type horizontal cells
to a negative feedback pathway from L-type horizontal cells
onto M-cones. Finally, the action spectra of each of the
three types of horizontal cells could not be solely accounted
for by input from one spectral type of cones. Only by assuming
excitatory and inhibitory inputs from all spectral types
of cones, the action spectra of all types of horizontal
cells could be reconstructed. These findings suggest that
the negative feedback pathways from horizontal cells onto
cones in the turtle retina cannot solely account for the
chromatic properties of the horizontal cells and support
a direct inhibitory inputs from cones to turtle horizontal
cells.
GABA sensitivity of spectrally classified horizontal cells
in goldfish retina
Authors: VERWEIJ J. , KAMERMANS M. , NEGISHI K. , SPEKREIJSE H.
Published: July 2002

We studied the GABA sensitivity of horizontal cells
in the isolated goldfish retina. After the glutamatergic
input to the horizontal cells was blocked with DNQX, GABA
depolarized the monophasic and biphasic horizontal cells.
The pharmacology of these GABA-induced depolarizations
was tested with the GABA receptor antagonists bicuculline-methiodide
and picrotoxin, the GABA transporter agonist nipecotic
acid, and the GABA transporter antagonist SKF 89976-A.
The GABA-induced responses of monophasic horizontal cells
consisted of two components; one with characteristics of
GABA-gated chloride channels, and one with characteristics
of GABA transporters. In biphasic horizontal cells, we
only found evidence for GABA-gated chloride channels. The
results show that monophasic horizontal cells in goldfish
contain the two components of a positive feedback loop
(GABA transporters and GABA-gated chloride channels), as
described in salamander. Furthermore, our results indicate
that the monophasic horizontal cells may project directly
to the biphasic horizontal cells, via an excitatory
GABAergic pathway. We propose that the function of these
GABAergic systems in horizontal cells is to abolish cone
dominance in bipolar cells surround in the dark-adapted
retina.
Light-stimulated release of dopamine from the primate retina
is blocked by l-2-amino-4-phosphonobutyric acid (APB)
Authors: BOELEN MEEUWIS K. , BOELEN MARY G. , MARSHAK DAVID W.
Published: July 2002

Macaca mulatta retinas were superfused,
in vitro, to measure the efflux of dopamine. Steady
light, in the low photopic range, stimulated dopamine release
slightly. Flashing light (3 Hz) superimposed over the steady
background increased dopamine efflux significantly. This
increase was completely blocked by the addition of
d,l-2-amino-4-phosphonobutyric acid (d,l-APB,
10–100 μM) to the superfusion medium, but not
by the addition of the inactive enantiomer d-APB
(10 μM). The results suggest that ON bipolar cells
provide the excitatory drive to dopaminergic amacrine cells
in primates, as in other species.
ON direction-selective ganglion cells in the rabbit retina:
Dendritic morphology and pattern of fasciculation
Authors: HE SHIGANG , MASLAND RICHARD H.
Published: July 2002

ON direction-selective (DS) ganglion cells were
identified by electrophysiological recordings in DAPI labeled,
isolated rabbit retinas. Their responses to a flashing
spot were sustained. Their responses to moving stimuli
were strong in the preferred direction and weak in the
null direction. Injection of the recorded cells with Lucifer
yellow revealed that the cells had a distinct dendritic
morphology, consistent with that described previously (Buhl
& Peichl, 1986; Amthor et al., 1989; Famiglietti, 1992a).
When neighboring cells were injected, an extensive dendritic
co-fasciculation was observed. The pattern of fasciculation
restricts the possible synaptic connections of the ON DS
cell.
Retinal image quality in the rodent eye
Authors: ARTAL PABLO , de TEJADA PILAR HERREROS , TEDÓ CARMEN MUÑOZ , GREEN DANIEL G.
Published: July 2002

Many rodents do not see well. For a target to be
resolved by a rat or a mouse, it must subtend a visual
angle of a degree or more. It is commonly assumed that
this poor spatial resolving capacity is due to neural rather
than optical limitations, but the quality of the retinal
image has not been well characterized in these animals.
We have modified a double-pass apparatus, initially designed
for the human eye, so it could be used with rodents to
measure the modulation transfer function (MTF) of the eye's
optics. That is, the double-pass retinal image of a monochromatic
(λ = 632.8 nm) point source was digitized with a CCD
camera. From these double-pass measurements, the single-pass
MTF was computed under a variety of conditions of focus
and with different pupil sizes. Even with the eye in best
focus, the image quality in both rats and mice is exceedingly
poor. With a 1-mm pupil, for example, the MTF in the rat
had an upper limit of about 2.5 cycles/deg, rather than
the 28 cycles/deg one would obtain if the eye were a diffraction-limited
system. These images are about 10 times worse than the
comparable retinal images in the human eye. Using our measurements
of the optics and the published behavioral and electrophysiological
contrast sensitivity functions (CSFs) of rats, we have
calculated the CSF that the rat would have if it had perfect
rather than poor optics. We find, interestingly, that diffraction-limited
optics would produce only slight improvement overall. That
is, in spite of retinal images which are of very low quality,
the upper limit of visual resolution in rodents is neurally
determined. Rats and mice seem to have eyes in which the
optics and retina/brain are well matched.