Kiyomi Nakamura

PLACE RECOGNITION RESPONSES OF NEURONS IN MONKEY HIPPOCAMPUS

Neuronal activity in the monkey hippocampus was recorded while the monkey sat in a rotatable cab which it could cause to move from one location to another by pressing bars, and while it was presented various visual stimulation from several horizontal directions (directional stimulation). Of 174 hippocampal neurons recorded, 20 were selective to direction of the stimulus without place relation. Responses of these neurons could be described in egocentric coordinates for some and allocentric coordinates for others. Seventy-seven neurons had place related activity (place related neurons). Of these place related neurons, 21 were also directionally selective with responses described in egocentric or allocentric coordinates or both. The results show close relations between the coding of environmental space cues in egocentric and allocentric coordinates, and place related activity in the primate hippocampus.

Integrated lateral hypothalamic neural responses to natural and artificial rewards and cue signals in the rat

Effects of natural and intracranial electrical rewarding stimuli and cue signals were investigated while recording from single neurons in the rat lateral hypothalamus. The rat obtained both rewards using identical behavior, viz. licking. When both rewarding stimuli influenced a neuron, the responses were usually similar, i.e. both excitatory or both inhibitory. Only neurons that responded to either or both rewards acquired responses to tone cues, and these acquired responses were in the same direction as reward responses. The data indicate that the same single neuron in the lateral hypothalamus might be implicated in reward processes and learning.

Recognition of egocentric and allocentric visual and auditory space by neurons in the hippocampus of monkeys.

Neuronal activity in the hippocampus was recorded in the awake monkey during presentation of visual and auditory stimuli from various directions. About 10% of the neurons coded visual and/or auditory information from unique directions. Some of these neurons were stimulus-selective, and others were not. Three types of neurons were identified by rotating the animals: egocentric and allocentric, and indeterminate. The results are consistent with a role of the hippocampus in spatial memory.

Highly reliable liveness detection method for iris recognition

The importance of personal authentication is increasing with the development of the information society. The accuracy of personal authentication by identifying the iris is higher than that by using other biometric traits such as faces or fingerprints. However, the iris authentication system is vulnerable to deception by a fake iris even though the recognition accuracy is high. In this study, we developed a liveness detection method by using a variation in the brightness of an iris pattern induced by a pupillary reflex. The live and artificial irises were classified by a decision threshold of 7% brightness variation rate.

Head-centered representation and spatial memory in rat posterior parietal cortex

Rodent posterior parietal cortex, similar to its homologue in primates, has been shown to be critically involved in spatial navigation. We summarize here selected neurophysiological data and their relevance to recent lesion-behavioral studies. The findings indicate that the rat posterior parietal cortex contains a significant proportion of neurons that code for head-centered (or body-centered) space by making use of the vestibular and proprioceptive inputs. Some posterior parietal neurons may store a working representation of space, which appears to be allocentric.

Chapter 28 Amygdalar and hippocampal neuron responses related to recognition and memory in monkey

Publisher Summary This chapter initially characterizes, in several ways, the responses of amygdalar and hippocampal neurons to affective sensory stimuli. Amygdalar and hippocampal neuronal responses to stimuli that are considered to be biologically significant are studied in various behavioral tasks that involve the discrimination of different rewarding and aversive stimuli. Some neurons are also tested by changing the affective significance of the stimuli presented. Comparison of amygdalar and hippocampal neuronal responsiveness to affective sensory stimuli elucidates differences in the functions of these two structures. Functional connections between the association cortex and medial temporal lobe (and the hypothalamus), which underlie amygdalar and hippocampal responsiveness to complex sensory stimuli, are investigated by analyzing neuronal response changes during reversible disconnection of the inferotemporal cortex from the amygdala, or disconnection of the amygdala from the hypothalamus, by cooling the inferotemporal cortex or the amygdale. Hippocampal neurons are analyzed in more detail by introducing a spatial factor. The chapter also discusses the experiments on monkey hippocampal neurons were recorded during performance of a spatial moving task.

Learning and integration of rewarding and aversive stimuli in the rat lateral hypothalamus

Single neuron activity was recorded in the lateral hypothalamus (LHA) and lateral preoptic-anterior hypothalamic area (IPOA-AHA) of the rat during discrimination learning of cue tones that predicted glucose or intracranial self-stimulation as rewarding stimuli, or electric shock or tail pinch as aversive stimuli, using identical behavior, licking. Rewarding and aversive stimuli had opposite effects on the same LHA neurons, but had the same effects on IPOA-AHA neurons. Neurons in the LHA that differentiated between reward and aversion acquired discrimination of the respective cue tones, while IPOA-AHA neurons responded in the same way to cue tones whether they preceded reward or aversion. The results suggest reward- and aversion-related integrative functions in the LHA and arousal or attentional functions in the IPOA-AHA.

Contribution of amygdalar and lateral hypothalamic neurons to visual information processing of food and nonfood in monkey.

Visual information processing was investigated in the inferotemporal cortical (ITCx)-amygdalar (AM)-lateral hypothalamic (LHA) axis which contributes to food-nonfood discrimination. Neuronal activity was recorded from monkey AM and LHA during discrimination of sensory stimuli including sight of food or nonfood. The task had four phases: control, visual, bar press, and ingestion. Of 710 AM neurons tested, 220 (31.0%) responded during visual phase: 48 to only visual stimulation, 13 (1.9%) to visual plus oral sensory stimulation, 142 (20.0%) to multimodal stimulation and 17 (2.4%) to one affectively significant item. Of 669 LHA neurons tested, 106 (15.8%) responded in the visual phase. Of 80 visual-related neurons tested systematically, 33 (41.2%) responded selectively to the sight of any object predicting the availability of reward, and 47 (58.8%) responded nondifferentially to both food and nonfood. Many of AM neuron responses were graded according to the degree of affective significance of sensory stimuli (sensory-affective association), but responses of LHA food responsive neurons did not depend on the kind of reward indicated by the sensory stimuli (stimulus-reinforcement association). Some AM and LHA food responses were modulated by extinction or reversal. Dynamic information processing in ITCx-AM-LHA axis was investigated by reversible deficits of bilateral ITCx or AM by cooling. ITCx cooling suppressed discrimination by vision responding AM neurons (8/17). AM cooling suppressed LHA responses to food (9/22). We suggest deep AM-LHA involvement in food-nonfood discrimination based on AM sensory-affective association and LHA stimulus-reinforcement association.

Neuron activity in and adjacent to the dorsal amygdala of monkey during operant feeding behavior

Neuronal activity of the dorsal amygdala, the substantia innominata and the ventral putamen during bar press operant behavior was analyzed to investigate neuronal responses in various affective situations. Of 1507 neurons recorded, 431 responded to some stimuli and were classified into 6 functional categories: 64 (4.2%) indiscriminately and transiently responded to various stimuli; 98 (6.5%) responded to various objects depending on their significance, whether rewarding or punishing; 44 (2.9%) clearly responded only to certain food or objects associated with potables, but not to both; 16 (1.1%) responded to both food and objects associated with potables; 35 (2.3%) responded primarily at the sight of certain nonfood; 66 (4.4%) responded primarily in the ingestion phase. Relations between function and topography are discussed. The results suggest that the dorsal AM and adjacent areas might be important in recognizing the biological significance of objects and in procuring food.

Characteristics of rat lateral hypothalamic neuron responses to smell and taste in emotional behavior

Single unit activity in the lateral hypothalamus (LHA) of the rat was recorded while the animal learned to discriminate cue signals. Normally preferred potables (glucose, orange, or grape solution) or intracranial self-stimulation (ICSS) were used as rewards. Electric shock or tail pinch were used as aversive stimuli. The same behavior, licking, was the response required to either obtain the rewarding stimuli or avoid the aversive ones. For positive reinforcement a rat was rewarded with fluid or ICSS upon licking a spout presented in front of its mouth. In negative reinforcement experiments, an aversive stimulus, electric shock or tail pinch, was applied if the rat did not lick the spout. Solutions having smell only, taste only, or smell-plus-taste, were prepared from oranges or grape extract. Of 392 neurons analyzed, 256 responded differentially to rewarding and aversive stimuli, and 138 of these were tested with the 3 different solutions. Similar LHA neural responses occurred during actual drinking of the 3 kinds of solutions, as well as on recognition of the cue signal. Responses to smell only had shorter latency than responses to taste only. Neural activity in response to solutions that could be both smelled and tasted was the sum of activity in response to taste-only solutions plus that in response to smell-only solutions. Cue signal responses were rapidly acquired, usually within 2-5 trials, for both taste-only and smell-only solutions. The results indicate the integration of both taste and olfactory information by the same LHA neurons, and these neurons are involved in cue signal learning. Present results of LHA neuronal responses to taste and smell suggest that the intensity of gustation and olfaction may add together to enhance instinctive hedonic sensations. These neurons are involved in the formation of stimulus-reinforcement association in learning, and in elicitation of conditioned emotional responses.