Biomedical subjects

Yuan-Ye Ma

Publications and source records attributed to Yuan-Ye Ma.

7 recordsLinked to original sources

PubMed2006

Neurophysiological recordings in freely moving monkeys.

Recordings of neuronal activity in freely moving rats are common in experiments where electrical signals are transmitted using cables. Such techniques are not common in monkeys because their prehensile abilities are thought to preclude such techniques. However, analysis of brain mechanisms underlying spatial navigation and cognition require the subject to walk. We have developed techniques for recordings in freely moving monkeys in two different situations: a 5 x 5 m testing laboratory and in a 50 m2 open field environment. Neuronal signals are sent to amplifiers and data acquisition systems using cables or telemetry. These techniques provide high quality recordings of single neurons during behaviors such as foraging, walking, and the performance of memory tasks and thus provide a unique opportunity to study primate behavior in a semi-natural situation.

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PubMed2005

An automated food delivery system for behavioral and neurophysiological studies of learning and memory in freely moving monkeys.

We describe a custom-built feeder based on stepping motor technology controlled by a laboratory computer. The feeder dispenses a wide range of foods: any fruit, vegetable, or nut. The feeder allows the investigator to reward monkeys with different foods within a single experimental day. The monkey's motivation to perform tasks is high and does not rely upon food regulation. The avoidance of regulation, as well as the palatability and variety of the rewards dispensed by our device, distinguishes it from commercially available products. We also describe the use of the feeder in the context of novel behavioral and neurophysiological studies in freely moving monkeys.

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PubMed2004

[Methods for single unit recording in behavioring morphine craving rat].

In this paper, one method was introduced, which was a combination of the cue-related morphine addiction model and a technique for obtaining chronic extracellular recordings of single unit in freely moving rats. With the combination and improvement of this technique, we have successfully applied this new method to study the neuronal activity of the hippocampus CA1 region in morphine withdrawal rats. In all, we found some more accurate and objective cellular characteristics of hippocampal neurons, and considered these characteristics as one of electrophysiological indexes of morphine addiction rats.

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PubMed2004

Reinforcement-related neurons in the primate basal forebrain respond to the learned significance of task events rather than to the hedonic attributes of reward.

The objective of this study was to determine if the responses of basal forebrain neurons are related to the cognitive processes necessary for the performance of behavioural tasks, or to the hedonic attributes of the reinforcers delivered to the monkey as a consequence of task performance. In all cases, it was found that the primary neuronal responses were to visual stimuli that required analysis important for the selection of a behavioural response and not to the delivery of reinforcement per se. Indeed, reinforcement-related neurons that responded only to the delivery of juice or of saline were never encountered. In additional experiments, it was found that abstract visual cues-specific gestures of the experimenter-that signaled the impending delivery of reinforcement were able to activate these neurons. These data are consistent with the view that reinforcement-related basal forebrain neurons influence the sensory and motor processes in the cerebral cortex, providing control signals that optimise the processing of complex sensory stimuli and/or the generation of appropriate behavioural responses.

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PubMed2004

Spatially directed movement and neuronal activity in freely moving monkey.

The abilities to plan a series of movements and to navigate within the environment require the functions of the frontal and ventromedial temporal lobes, respectively. Neuropsychological studies posit the existence of egocentric (prefrontal) and allocentric (ventromedial temporal) spatial frames of reference that mediate these functions. To examine neural mechanisms underlying egocentric and allocentric guidance of movement, we have developed behavioral and neurophysiological techniques for freely moving monkey. In this chapter, we provide evidence that the dorsolateral prefrontal cortex is important for egocentric spatial tasks in both the visual and tactile modalities, but it does not contribute to performance of an allocentric spatial task. Moreover, neurophysiological recordings indicate that prefrontal neurons are involved in monitoring the spatial nature of behavioral sequences in an egocentric memory task. In contrast, hippocampal neurons are active during spatially directed locomotion, apparently reflecting the monkey's location in a testing room. This discharge is independent of the task's contingencies.

Animals↗

PubMed2003

Dissociation of egocentric and allocentric spatial processing in prefrontal cortex.

Monkeys with lesions of areas 9 and 46 performed three variants of the spatial delayed response (SDR) task. There were no impairments in allocentric spatial memory in which geometrical relationships between environmental cues were used to identify spatial location; thus, memory of a 3D environmental map is intact. In contrast, there were severe impairments in egocentric spatial memory guided by visual or tactile cues that monkeys can relate to their viewing perspective during testing. These results strongly suggest that dorsolateral prefrontal cortex selectively mediates spatial memory tasks that are solved by referencing the location of targets to the body's orientation.

Animals↗

PubMed2003

A microelectrode drive for long term recording of neurons in freely moving and chaired monkeys.

An electrode drive is described for recordings of neurons in freely moving and chaired monkeys during the performance of behavioural tasks. The electrode drives are implanted for periods of up to 6 months, and can advance up to 42 electrodes using 14 independent drive mechanisms. The drive samples 288 points within a 12 mmx12 mm region, with 15 mm of electrode travel. Major advantages are that recordings are made in freely moving monkeys, and these recordings can be compared with those in chaired experiments; waveforms of single neurons are stable, enabling prolonged recordings of the same neurons across periods of days; recordings can be made throughout the brain, including the dorsolateral prefrontal cortex and hippocampus; the drive accommodates both sharp microelectrodes and fine wire assemblies such as tetrodes.

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