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E T Rolls

Publications and source records attributed to E T Rolls.

At least 145 records · Page 8Linked to original sources
PubMed1985

A technique for microiontophoretic study of single neurones in the behaving monkey.

A technique is described for the construction and use of iontophoretic electrodes suitable for extracellular single-unit work in awake behaving monkeys. The technique combines a multi-barrelled pipette for iontophoresis and an insulated tungsten electrode that is employed routinely for chronic single-unit recordings. The pipette consists of up to 11 double filamented glass barrels concentrically arranged around a large diameter glass tube. The recording electrode is extruded through the central tube under microscopic control and glued in place. This technique allows separate optimization of the shape of the recording electrode for recording in the behaving monkey, and of the iontophoretic tips. An adapted micropositioner is used to accommodate the electrode's unusual length, required in order to allow access to deep brain structures and so that a guide tube can protect the trans-dural passage of the electrode tip.

Animals↗
PubMed1985

Neurons in the amygdala of the monkey with responses selective for faces.

To investigate the functions of the amygdala in visual information processing and in emotional and social responses, recordings were made from single neurons in the amygdala of the monkey. A population of neurons (40 of more than 1000 recorded in 4 monkeys) was investigated which responded primarily to faces. These neurons typically (1) responded to some human or monkey faces, which were presented to the monkey through a large aperture shutter so that response latencies could be measured, or were simply shown to the monkey, (2) responded to 2-dimensional representations of these faces, as well as to real 3-dimensional faces, (3) had no responses or only small (less than half maximum) responses to gratings, simple geometrical, other complex 3-D stimuli, or to arousing and aversive stimuli, (4) had response latencies of 110-200 ms, (5) were located in the basal accessory nucleus of the amygdala, (6) responded differently to different faces, as shown by measures of d', and could thus over a population of such neurons code information useful for making different responses to different individuals, (7) could in some cases (9/11 tested) respond to parts of faces, and (8) in a few cases (4/19 tested) responded more to a face which produced an emotional response. A comparison made in three monkeys of the responses of these neurons with the responses of 77 neurons with face-selective responses recorded in the cortex of the superior temporal sulcus (STS) showed that the amygdaloid neurons had longer response latencies (110-200 compared to 90-140 ms), and were in some respects more selective in their responses to different faces. It is suggested that the deficits in social and emotional behavior produced by amygdala lesions could be due in part to damage to a neuronal system specialized in utilizing information from faces so that appropriate social and emotional responses can be made to different individuals.

Amygdala↗
PubMed1984

Responses of striatal neurons in the behaving monkey. 2. Visual processing in the caudal neostriatum.

The activity of single neurons was recorded in the tail of the caudate nucleus and adjoining part of the ventral putamen, which receive projections from the inferior temporal visual cortex, in order to investigate the functions of these regions. Of 195 neurons analyzed in two macaque monkeys, 109 (56%) responded to visual stimuli, with latencies of 90-150 ms for the majority of the neurons. The neurons responded to a limited range of complex visual stimuli, and in some cases responded to simpler stimuli such as bars and edges. Typically (in 75% of cases) the neurons habituated rapidly, within 1-8 exposures, to each visual stimulus, but remained responsive to other visual stimuli with a different pattern. This habituation was orientation specific, in that the neurons responded to the same pattern shown in an orthogonal orientation. The habituation was also relatively short-term, in that at least partial dishabituation to one stimulus could be produced by a single intervening presentation of a different visual stimulus. These neurons were relatively unresponsive in a visual discrimination task, having habituated to the stimuli which had been presented in the task on many previous trials. It is suggested on the basis of these results and other studies that these neurons are involved in pattern-specific habituation to repeated visual stimuli, and in attention an orientation to a changed visual stimulus pattern. Changes in attention and orientation to stimuli as a result of damage to the striatum and its afferent and efferent pathways may arise in part because of damage to neurons with responses of this type.

Animals↗
PubMed1984

Role of noradrenaline and serotonin in the basolateral region of the amygdala in food preferences and learned taste aversions in the rat.

First, it was confirmed that bilateral lesions in the basolateral region of the amygdala (ABL) of the rat increased the time spent eating novel as compared to familiar food in a food preference test, and that the lesions impaired learned taste aversion to a sucrose solution which had been paired with lithium chloride. Then the roles of noradrenaline and serotonin in the amygdala in these aspects of food intake were investigated. In Experiment 2, it was shown that injections of 10 and 20 nmoles of noradrenaline (NA) into the ABL increased the time spent eating familiar food in the food preference test. Higher doses of NA (50 and 100 nmoles) increased the total time spent eating without changing the preference of the rats for familiar or novel food, and produced behavioral side effects. Serotonin (5HT) injected into the ABL in doses of 10, 50 and 100 nmoles did not modify the pattern of choice of the foods. In Experiment 3, it was shown that depletion of NA in the ABL with 10 micrograms 6-hydroxydopamine did not alter the level of feeding of novel and familiar foods, but did impair taste aversion Depletion of 5HT in the ABL with 10 micrograms 5,7 dihydroxytryptamine did not alter food preferences or impair the taste aversion learning. The depletions of NA and 5HT were confirmed biochemically. These results provide further evidence for a role of the amygdala in preferences for novel as compared to familiar foods and in learning that the ingestion of a food is associated with sickness, and suggest that noradrenaline but not serotonin in the amygdala is involved in these types of control of food intake.

Amygdala↗
PubMed1984

Responses of striatal neurons in the behaving monkey. 3. Effects of iontophoretically applied dopamine on normal responsiveness.

In order to analyse the functions of dopamine, the effects of the iontophoretic application of dopamine on the responsiveness of striatal neurons to their normal inputs were investigated in the behaving monkey. It was shown that many neurons in the putamen had responses related to movements, of for example the mouth. Iontophoretically applied dopamine decreased the spontaneous firing rates of 178 of 267 neurons (67%) tested in the putamen, caudate nucleus, and the adjacent prefrontal cortex which also receives a dopaminergic projection. Trifluoperazine, applied iontophoretically to block dopamine receptors, increased the spontaneous firing rates of some of the neurons in the prefrontal cortex, suggesting that under normal conditions in the behaving animal the release of dopamine holds the firing rates of these neurons at a low level. The median was 9 spikes/s in the present sample of striatal neurons. Application of dopamine decreased the magnitude of the movement-related responses of the striatal neurons; this decrease in the responses was of approximately the same magnitude in spikes per second as the decrease in the spontaneous firing rate of the neurons produced by the same current of dopamine. It is suggested that this type of effect of dopamine could influence the signal to noise ratio of processing within the striatum, and that changes in this signal to noise ratio produced by disturbances of dopaminergic function could contribute to the behavioral disorders produced by dysfunctions of the dopaminergic systems.

Animals↗
PubMed1984

Pleasantness changes and food intake in a varied four-course meal.

Satiety can be specific to a food which has been eaten. This is shown by a decrease in the pleasantness of foods eaten relative to foods which have not been eaten. The aim of the present experiment was to determine whether this specificity still remained after a meal with a very different food in each of four courses. Forty-eight human subjects were given a four-course lunch with either a different food in each course (varied meal), or the same food in each course (plain meal). Energy intake was elevated by 60% in the varied meal primarily because of the increase food consumption in the third and fourth courses. The pleasantness of the taste of foods eaten decreased rapidly, whereas the pleasantness of foods which had not been eaten remained relatively unchanged. The change in pleasantness of a food correlated well with the subsequent intake of that food. Therefore, sensory-specific satiety is still found after eating four different courses in a meal and general satiety does not result. Some selective interactions between different foods were also found. For example, when a savory food was eaten, the pleasantness of (uneaten) savory foods decreased more than that of (uneaten) sweet foods. The converse was found when sweet foods were eaten. It is concluded that sensory-specific satiety and the effect of variety in enhancing food intake can operate throughout a meal with four very different foods, and that there are interactions between foods similar in savoriness or sweetness.

Adolescent↗
PubMed1984

The neurophysiology of feeding.

Investigations in non-human primates have provided evidence that the lateral hypothalamus and adjoining substantia innominata are involved in the control of feeding, for there is a population of neurons in these regions which respond to the sight and/or taste of food if the organism is hungry. The responses of these neurons may reflect the rewarding value or pleasantness of food, for stimulation in this region can mimic the reward value of food. It has been found that although after satiation with one food these neurons no longer respond to that food, they may still respond at least partly to other foods which have not been eaten. Following this finding, it has been shown that sensory-specific satiety is an important determinant of human food intake, and that associated with this, variety is an important factor in determining the amount of food eaten. A route for information about which visual stimuli are foods to reach the hypothalamus is provided by temporal lobe structures such as the inferior temporal visual cortex and amygdala, with the amygdala being important for learning which visual stimuli are foods. The orbitofrontal cortex contains a population of neurons which appear to be important in correcting feeding responses as a result of learning. The striatum contains neural systems which are important for the initiation of different types of motor and behavioural responses, including feeding.

Animals↗
PubMed1984

Neurons in the cortex of the temporal lobe and in the amygdala of the monkey with responses selective for faces.

There are populations of neurons in the temporal lobe of the macaque which appear to be specialised to respond to faces. These neurons are relatively rare in the inferior temporal visual cortex, area TE, but are more common in the cortex in the middle and anterior parts of the superior temporal sulcus. In some cases these neurons can respond to parts of faces such as the eyes, and in other cases a fuller complement of the features present in faces, with even the correct configuration of these features, appears to be necessary for these neurons to respond. In experiments to investigate whether the responses of these neurons would be useful for recognition of an individual, it has been shown that in many cases (77% of one sample), these neurons are sensitive to differences between faces. In experiments designed to investigate the information required for these neurons to respond, it has been shown that these neurons can respond to blurred images of faces, and to faces with only the high spatial frequencies included. A population of neurons with face-selective responses has also been found in the amygdala, which receives inputs from the temporal lobe visual cortex. In many cases these neurons respond differently to different faces. It is suggested that the importance of this type of neuron may be in the different emotional and social responses which occur to different faces, and which are disrupted by damage to the amygdala.

Amygdala↗
PubMed1983

The orbitofrontal cortex: neuronal activity in the behaving monkey.

Single unit recording of neurons in the orbitofrontal cortex of the alert rhesus monkey was used to investigate responses to sensory stimulation. 32.4% of the neurons had visual responses that had typical latencies of 100-200 ms, and 9.4% responded to gustatory inputs. Most neurons were selective, in that they responded consistently to some stimuli such as foods or aversive objects, but not to others. In a number of cases the neurons responded selectively to particular foods or aversive stimuli. However, this high selectivity could not be explained by simple sensory features of the stimulus, since the responses of some neurons could be readily reversed if the meaning of the stimulus (i.e. whether it was food or aversive) was changed, even though its physical appearance remained identical. Further, some bimodal neurons received convergent visual and gustatory inputs, with matching selectivity for the same stimulus in both modalities, again suggesting that an explanation in terms of simple sensory features is inadequate. Neurons were also studied during the performance of tasks known to be disrupted by orbitofrontal lesions, including a go/no go visual discrimination task and its reversal. 8.6% of neurons had differential responses to the two discriminative stimuli in the task, one of which indicated that reward was available and the other saline. Reversing the meaning of the two stimuli showed that whereas some differential units were closely linked to the sensory features of the stimuli, and some to their behavioural significance, others were conditional, in that they would only respond if a particular stimulus was present, and if it was the one being currently rewarded. Other neurons had activity related to the outcome of the animal's response, with some indicating that reinforcement had been received and others, that an error had been made and that a reversal was required. Thus, neurons in the orbitofrontal cortex possess highly coded information about which stimuli are present, as well as information about the consequences of the animal's own responses. It is suggested that together they may constitute a neuronal mechanism for determining whether particular visual stimuli continue to be associated with reinforcement, as well as providing for the modification of the animal's behavioural responses to such stimuli when those responses are no longer appropriate.

Animals↗
PubMed1983

Sensory-specific and motivation-specific satiety for the sight and taste of food and water in man.

In normal weight humans it was shown first that the sight of food is pleasant when hungry, and that the pleasantness of the sight of a food which has been eaten to satiety decreases more than the pleasantness of the sight of foods which have not been eaten. Thus the specificity of satiety extends to the visual modality, and this may be an important factor in influencing which foods are selected for ingestion. Second, it was shown that the pleasantness of both the sight and taste of food are modulated in a motivation-specific manner, in that in hungry and thirsty humans the pleasantness of the sight and taste of food but not water is decreased by eating to satiety, and the pleasantness of the sight and taste of water but not food is decreased by drinking water to satiety. Third, it was shown that sensory-specific decreases in the pleasantness of the taste of a particular food produced by its ingestion are associated with only minor changes in the intensity of its taste, which do not account for the changes in pleasantness as shown by an analysis of covariance and by the relation between pleasantness and intensity, so that it is unlikely that sensory adaptation is an important part of the mechanism of sensory-specific satiety.

Adult↗
PubMed1983

Activity of neurons in the ventral tegmental region of the behaving monkey.

To investigate the functions of neurons in the ventral tegmental area, recordings were made of the activity of 257 single neurons in this area in the behaving monkey. Four main types of neuronal response were found in the ventral part of the tegmentum. First, neurons with activity phasically related to mouth or arm movements were found. Most of these were located relatively far lateral, close to the junction of the midbrain reticular formation with the zona incerta, or were in the substantia nigra, pars reticulata. Second, neurons were found which responded differentially in a visual discrimination task on trials on which the monkey had to initiate a licking response compared with trials on which he did not, and which also altered their firing rate tonically while mouth movements were being made in other situations (differential motor neurons). These were found mainly in the midbrain reticular formation, consistent with the view that populations of neurons in these regions are involved in the execution of movements. Third, neurons which also responded differentially in the visual discrimination task, but did not respond when the same movements were made in other situations, were found in the ventral tegmental area, in a region medial to and in some cases immediately dorsal to the substantia nigra pars compacta. Fourth, neurons which responded to cues such as a tone which enabled the monkey to prepare for performance on each trial of the visual discrimination task were found in the ventral tegmental area close to the midline. These third and fourth types of neurons were thus found in the region where neurons of the mesocortical and mesolimbic pathways are located. Their responses are similar to those of neurons found in the striatum, and it is suggested that they are important in enabling the animal to prepare for and then to engage in particular behavioral responses.

Animals↗
PubMed1982

Visual neurones responsive to faces in the monkey temporal cortex.

Of 497 single neurones recorded in the cortex in the fundus of the superior temporal sulcus (STS) of three alert rhesus monkeys, a population of at least 48 cells which were selectively responsive to faces had the following response properties: (1) The cells' responses to faces (real or projected, human or rhesus monkey) were two to ten times as large as those to gratings, simple geometrical stimuli or complex 3-D objects. (2) Neuronal responses to faces were excitatory, sustained and were time-locked to the stimulus presentation with a latency of between 80 and 160 ms. (3) The cells were unresponsive to auditory or tactile stimuli and to the sight of arousing or aversive stimuli. (4) The magnitude of the responses of 28 cells tested was relatively constant despite transformations, such as rotation, so that the face was inverted or horizontal, and alterations of colour, size or distance. (5) Rotation to profile substantially reduced the responses of 21 cells (31 tested). (6) Masking out or presenting parts of the face (i.e. eyes, mouth or hair) in isolation revealed that different cells responded to different features or subsets of features. (7) For several cells, responses to the normal organisation of cut-out or line-drawn facial features were significantly larger than to jumbled controls. These findings indicate that explanations in terms of arousal, emotional or motor reactions, simple visual feature sensitivity or receptive fields are insufficient to account for the selective responses to faces and face features observed in this population of STS neurones. It appears that these neurones are part of a system specialised to code for faces or features present in faces, and it is suggested that damage to this system is related to prosopagnosia, or difficulty in face recognition, in man and to the tameness and social disturbances which follow temporal lobe damage and are part of the Klüver-Bucy syndrome in the monkey.

Animals↗
PubMed1982

How sensory properties of foods affect human feeding behavior.

The sensory properties of food which can lead to a decrease in the pleasantness of that food after it is eaten, and to enhanced food intake if that property of the food is changed by successive presentation of different foods, were investigated. After eating chocolates of one color the pleasantness of the taste of the eaten color declined more than of the non-eaten colors, although these chocolates differed only in appearance. The presentation of a variety of colors of chocolates, either simultaneously or successively, did not affect food intake compared with consumption of the subject's favorite color. Changes in the shape of food (which affects both appearance and mouth feel) were introduced by offering subjects three successive courses consisting of different shapes of pasta. Changes in shape led to a specific decrease in the pleasantness of the shape eaten and to a significant enhancement (14%) of food intake when three shapes were offered compared with intake of the subject's favorite shape. Changes in just the flavor of food (i.e., cream cheese sandwiches flavored with salt, or with the non-nutritive flavoring agents lemon and saccharin, or curry) led to a significant enhancement (15%) of food intake when all three flavors were presented successively compared with intake of the favorite. The experiments elucidate some of the properties of food which are involved in sensory specific satiety, and which determine the amount of food eaten.

Adolescent↗
PubMed1982

Neuronal responses related to visual recognition.

To analyse the neural basis of long-term memory, recordings were made from single neurons in monkeys performing a visual recognition task of the type impaired in anterograde amnesia in man. Each visual stimulus was shown twice per day, once as novel, and after 0 to 17 other intervening items in the recognition task, on a second trial, as familiar, when the monkey could lick to obtain fruit juice if he recognized the stimulus correctly. At the anterior border of the thalamus, a population of neurons was found which responded to the stimuli only when they were familiar. The activity of these neurons was not related to lick responses. Further, in a different, visual discrimination, task, a number of these neurons were found to respond both to the familiar rewarded stimulus to which the monkey always licked, and to the familiar aversive stimulus to which he did not lick. This shows that in a reward association task these neurons respond on the basis of familiarity, providing evidence for a dissociation of recognition and associative memories. Analysis of the responses of these neurons in the continuous visual recognition task showed that the responses to familiar stimuli were time-locked to the onset and duration of the visual stimulation (brief exposures producing brief responses). The response latencies were in the range 100 to 200 ms. A 100 ms exposure of the stimulus was sufficient for the stimulus to be encoded, and a 100 ms exposure was also sufficient for a recognition related response. The magnitude of the neuronal response on trials with familiar stimuli decreased as the number of trials between the first (novel) and second (familiar) presentation of the same stimulus increased. The rate of this decay or 'forgetting' varied from cell to cell and was best described by an exponential function. Repeated exposure tended to slow the rate of forgetting, and two or three repeated presentations prolonged some cell 'memories' for more than 100 intervening trials. Although the majority of the neurons did not have such long 'memories', in that they responded as novel to stimuli seen on a preceding day, so that their responses could be related to recency but not to absolute recognition of ever having seen a stimulus before, 2 neurons did respond to stimuli which had not been seen for 24 h. The neurons showed some ability to respond to stimuli as familiar despite changes in viewing conditions and transformations such as 90 deg rotation. These findings indicate that the responses of these neurons at the anterior border of the thalamus are activated during recency or longer term recognition processing, both of which are impaired in anterograde amnesia in man. Measurement of the responses of these neurons, which appear to have access to memory mechanisms, has allowed parameters affecting such memory mechanisms to be investigated.

Amnesia↗
PubMed1982

Physiological mechanisms for thirst in the nonhuman primate.

The relationship between body fluid deficits and drinking has been investigated in a nonhuman primate. Intravenous sodium chloride infusions (0.93-3.25 M) given to rhesus monkeys caused drinking correlated with increases in plasma osmolality and sodium concentrations. Sucrose infusions (0.3 M in 0.15 M NaCl) also caused drinking while equiosmolal urea infusions did not. It was found that the drinking threshold corresponded to a 2.3% increase in plasma osmolality. Water deprivation for 24 h caused significant cellular dehydration, as indicated by a 5.8% elevation in plasma osmolality that exceeded the threshold for thirst, and a significant hypovolemia as indicated by elevated plasma protein and hematocrit values. Intravenous water preloads decreased plasma osmolality and produced a dose-related decrease in subsequent drinking. Infusions that restored plasma osmolality to predeprivation values, reduced intake by 85%. Intravenous isotonic saline preloads which abolished the hypovolemia did not have a consistent effect and reduced mean water intakes by only 3.2%. Thus in the rhesus monkey, cellular dehydration is an effective stimulus for thirst, and it is the primary determinant of drinking after water deprivation, used as an example of a natural thirst stimulus. In contrast to findings in nonprimates, the extracellular deficit contributes very little to drinking after water deprivation.

Animals↗
PubMed1981

Intracerebral self-administration of amphetamine by rhesus monkeys.

Four rhesus monkeys received intracranial implantation of cannulae aimed at the orbitofrontal cortex. Electrical intracranial self-stimulation was obtained readily from insulated electrodes placed temporarily into the orbitofrontal cortex via the outer guide tubes. Subsequently, each subject acquired a panel press operant response to deliver 0.05 microliter of D-amphetamine (10-6 M) into the orbitofrontal cortex via an inner cannula. The rate of panel pressing increased over several daily test sessions and extinguished after substitution of the vehicle solution. One animal responded readily on a fixed ratio-10 schedule. Control injections into the nucleus accumbens and lateral ventricles failed to maintain self-administration behavior.

Animals↗