Response of multiple simultaneously recorded macaque area LIP neurons in a memory saccade task

Cells in the lateral intraparietal cortex (LIP) of rhesus macaques respond vigorously and in spatially-tuned fashion to briefly memorized visual stimuli. Responses to stimulus presentation, memory maintenance, and task completion are seen, in varying combination from neuron to neuron. To help elucidate this functional segmentation a new system for simultaneous recording from multiple neighboring neurons was developed. The two parts of this dissertation discuss the technical achievements and scientific discoveries, respectively.

Technology. Simultanous recordings from multiple neighboring neurons were made with four-wire bundle electrodes, or tetrodes, which were adapted to the awake behaving primate preparation. Signals from these electrodes were partitionable into a background process with a 1/f-like spectrum and foreground spiking activity spanning 300-6000 Hz. Continuous voltage recordings were sorted into spike trains using a state-of-the-art clustering algorithm, producing a mean of 3 cells per site. The algorithm classified 96% of spikes correctly when tetrode recordings were confirmed with simultaneous intracellular signals. Recording locations were verified with a new technique that creates electrolytic lesions visible in magnetic resonance imaging, eliminating the need for histological processing. In anticipation of future multi-tetrode work, the chronic chamber microdrive, a device for long-term tetrode delivery, was developed.

Science. Simultaneously recorded neighboring LIP neurons were found to have similar preferred targets in the memory saccade paradigm, but dissimilar peristimulus time histograms, PSTH). A majority of neighboring cell pairs had a difference in preferred directions of under 45° while the trial time of maximal response showed a broader distribution, suggesting homogeneity of tuning with het erogeneity of function. A continuum of response characteristics was present, rather than a set of specific response types; however, a mapping experiment suggests this may be because a given cell's PSTH changes shape as well as amplitude through the response field. Spike train autocovariance was tuned over target and changed through trial epoch, suggesting different mechanisms during memory versus background periods. Mean frequency-domain spike-to-spike coherence was concentrated below 50 Hz with a significant maximum of 0.08; mean time-domain coherence had a narrow peak in the range ±10 ms with a significant maximum of 0.03. Time-domain coherence was found to be untuned for short lags (10 ms), but significantly tuned at larger lags (50 ms).

Macaque lateral intraparietal area and oculomotor behaviors

Neurons in the primate lateral intraparietal area (area LIP) carry visual, saccade-related and eye position activities. The visual and saccade activities are anchored in a retinotopic framework and the overall response magnitude is modulated by eye position. It was proposed that the modulation by eye position might be the basis of a distributed coding of target locations in a head-centered space. Other recording studies demonstrated that area LIP is involved in oculomotor planning. These results overall suggest that area LIP transforms sensory information for motor functions. In this thesis I further explore the role of area LIP in processing saccadic eye movements by observing the effects of reversible inactivation of this area. Macaque monkeys were trained to do visually guided and memory saccades and a double saccade task to examine the use of eye position signal. Finally, by intermixing visual saccades with trials in which two targets were presented at opposite sides of the fixation point, I examined the behavior of visual extinction.

In chapter 2, I will show that lesion of area LIP results in increased latency of contralesional visual and memory saccades. Contralesional memory saccades are also hypometric and slower in velocity. Moreover, the impairment of memory saccades does not vary with the duration of the delay period. This suggests that the oculomotor deficits observed after inactivation of area LIP is not due to the disruption of spatial memory.

In chapter 3, I will show that lesion of area LIP does not severely affect the processing of spontaneous eye movement. However, the monkeys made fewer contralesional saccades and tended to confine their gaze to the ipsilesional field after inactivation of area LIP. On the other hand, lesion of area LIP results in extinction of the contralesional stimulus. When the initial fixation position was varied so that the retinal and spatial locations of the targets could be dissociated, it was found that the extinction behavior could best be described in a head-centered coordinate.

In chapter 4, I will show that inactivation of area LIP disrupts the use of eye position signal to compute the second movement correctly in the double saccade task. If the first saccade steps into the contralesional field, the error rate and latency of the second saccade are both increased. Furthermore, the direction of the first eye movement largely does not have any effect on the impairment of the second saccade. I will argue that this study provides important evidence that the extraretinal signal used for saccadic localization is eye position rather than a displacement vector.

In chapter 5, I will demonstrate that in parietal monkeys the eye drifts toward the lesion side at the end of the memory saccade in darkness. This result suggests that the eye position activity in the posterior parietal cortex is active in nature and subserves gaze holding.

Overall, these results further support the view that area LIP neurons encode spatial locations in a craniotopic framework and is involved in processing voluntary eye movements.

The marine protected area planning process in Washington state: Recommendations for increased effectiveness

In Washington State, the Department of Natural Resources (WA DNR) is responsible for managing state-owned aquatic lands. Aquatic reserves are one of many Marine Protected Area (MPA) designations in WA State that aim to protect sensitive aquatic and ecological habitat. We analyzed the designation and early planning processes of WA State aquatic reserves, identified gaps in the processes, and recommend action to improve the WA State aquatic reserve early planning approach. (PDF contains 4 pages)

Selection of efficient hanging ratios of gillnet on fish catch in Lake Kainji, as means of alleviating poverty among artisanal fishermen in Nigeria

Five experimental gillnet each measuring 50mx 3m nylon multi filament netting of 3" by210/2 mesh size were constructed using 40%, 45%, 50%, 55% and 60% hanging percentages, the report was carried out at Yunawa fishing village on the eastern bank of Lake Kainji. The nets were set over night (6 hours approximately). Between April-July 2004, the fish caught by the five nets were recorded taking into consideration the three mode of capture i.e. enmeshing entanglement and wedging Weight number and percentage mean weight and number based on species at five different hanging ratios were analyzed in general 50% hanging ratio was found to be the best followed by 40% among others. There was significant difference (P<0.05) in the mode of capture for both hanging ratios. Most of the fish were caught by entanglement i.e. about 83% of the catch was by entanglement while 505 hanging ratio was the best considered after the report. The occurrence of species of the five hanging ratios has significant difference (P<0.05) in terms of catch by weight and number

Marketing of fishing gear materials and fishing gear making in parts of Kainji Lake basin

The importance of fishing gear in fishing cannot be over-emphasized; as without it fish cannot be obtained. The method used to catch fish affects the condition in which the product is landed. This means that a bad-catching method would produced bad fish to the consumer. To achieve the goal of self-sufficiency in fish production in Nigeria, there is need to address the lingering problems of fishing gear and craft technology, especially in terms of availability of materials and their cost. The sale and making of fishing gear materials are two areas of fisheries, which are yet to be exploited by the general public as forms of businesses for livelihood. The study is conducted in villages around the lower part of Kainji Lake, towards the dam, including New Bussa. It reveals that only the fishermen themselves are involved in making their own fishing gears while those involved in the selling of fishing gear materials like the sheet netting, ropes, twines, floats, sinkers etc are business men and women who may not have any experience of fishing. Also considered in the study is the art of making fishing crafts like the canoe and gourd. Very few entrepreneurs are involved and they are so skilled that each is specialized in the making of only one kind of craft or gear

Impact of Nigerian Agricultural Cooperative and Rural Development Bank (NACRDB) loan to artisanal fishermen in Lake Kainji

This study was conducted to assess the impact of Nigerian Agricultural, Co-operative and Rural Development Bank Loan on beneficiaries and non-beneficiaries fishermen in Lake Kainji. A total of fifty fishermen (25 beneficiaries and 25 non-beneficiaries) were randomly selected from five fishing villages along the lake basin. Data collected were scored and the percentages of the parameters were calculated appropriately. The types of loans disbursed to beneficiaries revealed that 52% was cash and 48% was in kind. The credit package ranged between N5, 000 to N150, 000 only. Only 48% of the loans granted were paid while the rest remained unpaid. The results obtained from the membership of fishermen Cooperative showed that 64% of beneficiaries were members while 36% were non-members. Also 36% of non-beneficiaries were members while 64% were not. The Common fishing gears used by the two categories of fishermen include gillnets longline, castnet and driftnets. Sixty percent of beneficiaries and 8% of non-beneficiaries fishermen were using canoe with outboard engines while the rest used canoes with paddles. Beneficiaries earned a higher income (N1, 000 to N9, 000) daily than non-beneficiaries (N1, 000 to N6, 000) daily from sales of fish caught. Major contrainsts to increased catch and income identified include inadequate capital, non- availability of fishing inputs, stealing of fishing gears, lack of access to credit facilities and menace of stump and water hyacinth in the lake. Lastly, recommendation were made for the bank management, government and other lending institutions on how to improve the livelihood of the Artisanal fishermen by increasing the loan usually granted

Characterization of rural livelihood of Lake Chad basin fishermen

The study examined the characterization of rural livelihood of the fishermen in the Nigeria portion of Lake Chad Basin are as part of European Commission (EC) founded project entitled "Sustainable development of continental fisheries; a regional study of policy options and policy formation mechanisms for the Lake Chad Basin" Wealth ranking exercise which was not based on real income but on production capacity of the fishermen was carried out in twenty (20) villages survey on the western part of the region using Rapid Rural Appraisal Technique with semi- structured interviews. The different activities carried out by the villagers for living were identified according to their socio-economic status. This was followed by an assessment of the socio-economic characterization within each wealth group. Series of comparative analysis of the ethnic composition, accessibility of fishing gear ownership by the population were done. The results show that the 3 wealth groups in the region include the rich (Group 1) the middle class (Group 2) and the poor (Group 3). It was identified that fishing is just one component of the socio-economic production system along side farming, livestock rearing and trading which are closely integrated. The diversified livelihood system being practiced in the Chad Basin region are not only less vulnerable but also more sustainable

Impact of radio broadcast on fish production and conservation in Kainji Lake basin

The decline in fishermen catches of Lake kainji, which went down from 28,639.6t in 1970 to 6.048t in 1974 (Ita 1982) prompted the promulgation of fisheries edict banning beach seines and other obnoxious fishing gear by Kebbi and Niger State governments in 1997 as a measure to prevent depletion of fisheries resources in the lake. Radio as a medium of communication was adopted as the method to disseminate information in the fisheries edict to the fisherfolks in order to bring about positive changes. Radio Niger, Koro station, was involved in the broadcast. Fisherfolk listened to the broadcast 32 times a week. Frame survey data and radio impact assessment studies were used to assess the effect of the broadcast on the number of beach seines and other obnoxious fishing gears on the lake which were banned in the fisheries edicts. It was revealed that the number of beach decreased drastically from 582 in 1997 to 122 in 1999 and to only 17 in 2001

Additional income generating activities for fishermen wives in Kainji Lake basin

The quest for food security and poverty alleviation among rural fisherfolks is imperative in the context of rural development. Rural fishermen and women do not only partake in fishing and related activities in order to make ends meet but also seek more sustainable ways of absorbing shocks and reducing their vulnerability to unforeseen economics conditions. These they do through diversification of their efforts to such activities that enables them have good leverage over poverty and food scarcity. It is in this context that Nigerian-German Technical Co-operation (GTZ) sought to assist the fisherfolks to help themselves by training the fishermen wives on knowledge and skill acquisition in Soya bean processing and utilization as a means of generating additional income for the household in Kainji Lake basin. This work was therefore carried out in order to make an objective investigation into the impact of this training on the economy of the fisherfolks. Sixty respondents, who constitute fishermen wives, were randomly selected from twelve fishing villages in the basin. 76.7% of those interviewed affirmed that the project has increased their income while others agreed that it has actually reduced their expenditure on food while increasing food supply and variety for the household

Comparative study on the catch efficiency and size selection of entangling nets in Lake Kainji, Nigeria

The relative catch performance and selectively of gillnets and trammel nets were investigated in 12 sampling stations in Lake Kainji, Nigeria. 3 types of nets with dimensions 50mx3m were constructed using 76mm and 178mm meshsizes for two gillnets, 76mm and 178mm meshsizes for the lint and ar mour nets of the trammelnets respectively. All the nets were randomly ganged together to form a fleet of nine nets each, and were set twice in each of the 12 stations which gave a total of 24 fishing operations. A total of 365 fish weighing 88.9kg and belonging to 16 different species were caught in all the nets. The trammelnet had the highest catch by number and weight constituting 60% and 69.22% of the total catch and weight respectively with a relative species Diversity Index of 0.82. This was followed by 76mm gillnet which constituted 38.63% by number, 28.09% by weight, 0.69 relative Species Diversity Index. The 178mm gillnet had the least catch of 1.37% and 2.9% by number and weight respectively with 0.25 relative Species Diversity Index. There was significant difference (P<0.05) in the number and weight of fish caught in the different nets. The minimum selection length for these species caught were the same for each net. The trammel net had a wider selection range that skewed to the right, a higher modal and median length indicating larger individual species being entangled in the net

Occupational practices and problems of rural artisanal fisherfolks in Oyan Dam area of Ogun State

Artisanal Fish Societies constitutes one of the poorest societies in the developing world. Attempts to harness the potentials of the societies have often failed due to the enormity of the problem of poverty. This study was conducted in four major fishing villages namely; Abule titun, Apojola, Imama Odo and Ibaro in order to investigate the occupational practices and the problems of rural artisanal fisherfolks in Oyam's Dam, area of Ogun State. Eighty respondents were randomly selected among the artisanal fisher folks for interview using interview guide. The findings revealed that 43.8% of the fisherfolks are within active range of 31-40 years while 30% are within 21-30 years range. Also 31% had no formal education indicating a relatively high level of illiteracy among the fisherfolks while majority of the respondents practice fishing activities using paddle and canoe. It was similarly discovered from the study that the most pressing problems of the fisherfolks is the lack of basic social amenities like electricity, potable water, access roads, hospitals and markets. It is therefore recommended that basic social infrastructures be provided for the artisanal fishing communities in order to improve their social welfare, standard of living and the capacity to have a sustainable fishing occupation in the interest of food security and poverty alleviation

The head-body weight and head-body length relationship of Synodontis schall (Bloch and Schneider 1801) in Asa Lake, Ilorin, Nigeria

A total of 710 specimens of Synodontis schall were analyzed for the head body weight and head body length relationship. The head constituted 40% of the total body weight and 30% of the total body length. The mean head weight for male and female computed was 23.90g and 29.13g respectively. Head weight in both male and female was significantly different (P<0.01) while the head length for the combined sexes showed no significant difference (P>0.05). Fat accumulation in the body tissue was prominent in the females than males usually before the breeding season. The significance of the cephalo-nuchal shield in the bony head of Synodontis species compared with some other catfishes in the lake was also discussed

Impact assessment of Niger State fisheries legislation on fisheries conservation in Edozhigi local government area (L.G.A.) of Niger State

A preliminary survey was conducted among the fishermen in five selected villages in Edozhigi L.G.A. of Niger State. One hundred and fifty fishermen were randomly selected and interviewed to find out the impact of Niger State fisheries legislation on fisheries conservation resources in the area. The analysis of data collected using descriptive statistics indicated that undersized mesh of gill nets, beach seines and traps are being used unabated. Also, fenced barriers across the entrance of flood plain ponds and Ex-bow lakes from the main stream are in the area. The fisheries rules and regulations implementers are rarely seen or not seen at all in the area. The decreasing nature of fish catches was detected. It is observed that government policy on fish conversation is neglected due to inadequate or lack of funding for meaningful extension and implementation of the fisheries rules and regulations

Parents aspiration and youth perception to sustainable fisheries development in Kainji Lake basin

Artisanal fisheries development in Nigeria, like in any other developing country of the world is characterized by subsistence level of operation using dugout canoe and paddle. This implies that parents and children constituted the labour in use since they only struggle for the upkeep of the family. A total of 240 questionnaires were used to solicit information from the respondents. This total was divided into 120 each for both parents and the youths respectively. Simple descriptive statistics such as frequency distribution and percentages were used to analyze their responses. Parents have strong aspiration for their children to succeed them hence, 78.3% of the parents expressed their aspiration for succession by the younger ones while 83.3% of parents tend to support their aspiration with persuasive strategies such as allowing their children to partake in fishing activities at will. On the part of the youth over 70% of them perceived fishing as a viable business where they can succeed their parents provided government can come to their aid in form of active involvement in the development of rural fisheries. It is therefore believed that fisheries development could achieve rapid improvement if the aspiration of the parents is balanced with perception of the youth and the government meets their expectation

Evaluation of woman fisherfolks involvement in fisheries activities in Kainji Lake basin

The extent of rural women fisherfolks contribution to fisheries was grossly under estimated and certainly under valued. The basis of their involvement in fisheries activities is to make themselves equal partners to men productive and self reliant participants in the process of improving their own and their family living standard and to enable them realize their full potentials. This survey is informed a system of data collection with the aid of questionnaires and analysis. Ninety-six of the questionnaires were administered to women fisher folks in eight fishing communities selected at random. Thirty seven (97) percent of the women fisher folks are between the ages of 25-35 years, 59.4% of them can only read and write in Arabic language and 21.9% only are literature in western education, which is a general characteristic of the rural population in Nigeria. 24.0% of the respondents are in full time fishing activities while 65-5% are fishmongers. They belong to cooperative societies but only 26% indicated to have benefited from loan and credit facilities. 84.4% of the respondents are sustained by the business. The major problems facing women fisherfolks includes poor market price, fish spoilage, high transport cost and lack of access to loan and credit facilities and extension assistance. Solution to these problems will increase their status benefit and development