Cogprints: No conditions. Results ordered Title. 2018-01-17T14:22:12ZEPrintshttp://cogprints.org/images/sitelogo.gifhttp://cogprints.org/2001-05-09Z2011-03-11T08:54:36Zhttp://cogprints.org/id/eprint/1380This item is in the repository with the URL: http://cogprints.org/id/eprint/13802001-05-09ZThe Correlation Theory of Brain FunctionA summary of brain theory is given so far as it is contained within the framework of Localization Theory. Diffculties of this "conventional theory" are traced back to a specific deficiency: there is no way to express relations between active cells (as for instance their representing parts of the same object). A new theory is proposed to cure this deficiency. It introduces a new kind of dynamical control, termed synaptic modulation, according to which synapses switch between a conducting and a non- conducting state. The dynamics of this variable is controlled on a fast time scale by correlations in the temporal fine structure of cellular signals. Furthermore, conventional synaptic plasticity is replaced by a refined version. Synaptic modulation and plasticity form the basis for short-term and long-term memory, respectively. Signal correlations, shaped by the variable network, express structure and relationships within objects. In particular, the figure-ground problem may be solved in this way. Synaptic modulation introduces flexibility into cerebral networks which is necessary to solve the invariance problem. Since momentarily useless connections are deactivated, interference between different memory traces can be reduced, and memory capacity increased, in comparison with conventional associative memory.Christoph von der Malsburg2001-05-08Z2011-03-11T08:54:37Zhttp://cogprints.org/id/eprint/1481This item is in the repository with the URL: http://cogprints.org/id/eprint/14812001-05-08ZDopaminergic agonistic and antagonistic drugs in the ventral tegmentum of rats inhibit and facilitate changes of food-search behaviourIntroduction:
The proposal that an increase of dopaminergic (DA) activity in the mesocorticolimbic pathway with an origin in the ventral tegmental area (VTA A10) increases the probability of behavioural change was tested (Koob et al., 1978 - see also Oades, 1985 on the switching role of DA)
Methods:
Food-deprived animals searched for food pellets placed consistently in 4 holes of a 16-hole-board. They were presented with 9 sessions of 10 trials/session. Groups of rats received lesions of the VTA or injections of the DA D2 antagonist spiroperidol (2µg/0.5 µl) or the DA agonist apomorphine (2 µg(0.5µl) into the VTA before sessions 4 and 7.
[Neuroleptic treatment should block local inhibition via autoreceptors and thus lead to increased DA activity in the terminal regions]
Results:
1/ Compared to vehicle- or apomorphine-treatment, spiroperidol increased the number of empty hole-visits (errors)
2/ Comparison animals (vehicle- and apomorphine treated) developed individually specific but consistent sequences of hole-visits ("strategy") -- these were disrupted on sessions 4 and 7 after neuroleptic treatment and following VTA damage.
(i.e. there was much intra-session switching between sequences from trial to trial.)
3/ Further the identity of the preferred sequence on session 7 was more often different than on session 4 for lesioned and neuroleptic treated animals than for the comparison groups.
(i.e there was also inter-session switching between sequences between sessions 4 and 7.)
4/ Although many apomorphine-treated animals changed their preference on session 4, this was not repeated after the second treatment on session 7 - when fewer changes were recorded than for the controls..
Conclusions:
.The results are consistent with increased switching of strategies in animals with increased mesocorticolimbic DA activity - where the learning and maintenance of strategies are seen as an aid to recall the adaptive sequence of behaviour likely to lead to the relevant baited holes.
Oades2007-10-22T10:41:27Z2011-03-11T08:56:58Zhttp://cogprints.org/id/eprint/5765This item is in the repository with the URL: http://cogprints.org/id/eprint/57652007-10-22T10:41:27ZThe effect of pregnancy and stress on the onset of placentophagia in Long-Evans rats Most virgin rats do not eat placenta when it is presented to them; virtually all parturient rats do. This study was designed to examine the role of the duration and termination of pregnancy on the induction of placentophagia. Time-bred rats determined by a pretest not to be attracted to placenta (nonplacentophages), were tested for placentophagia on one of a number of days of pregnancy. A comparable group was tested for placentophagia after surgical termination of pregnancy on Day 21. Groups of virgins were run controlling for the time interval between the pretest and the placentophagia test, and for a time interval that included a "stressful" event. The results were that (a) the incidence of placentophagia rose gradually from Day 7 to Day 15 of pregnancy, then remained stable, at about 0.4 until delivery; (b) pregnancy termination did not produce an effect on placentophagia greater than that of unterminated pregnancy; (c) a pretest-test interval containing a "stressful" event produced significantly more placentophagia than one that did not contain such an event; and (d) the maximum level of placentophagia observed during pregnancy was the same as that produced in virgins by a "stressful" event.Dr. Mark B. Kristalkristal@buffalo.eduL. C. PetersJ.R. FranzJ.F. WhitneyJ. Ken NishitaM. A. Steuer2003-05-06Z2011-03-11T08:55:15Zhttp://cogprints.org/id/eprint/2907This item is in the repository with the URL: http://cogprints.org/id/eprint/29072003-05-06ZThe Evolution of Semantic Memory and Spreading ActivationThe purpose of this paper is to demonstrate that it is possible to deduce the structure of human semantic memory by mathematically analyzing the environment which through evolution has shaped it. The theory arrived at is similar to the spreading-activation theories of Quillian, and Collins and Loftus, but it contrasts with the above in that it involves a rigidly restricted activation that employs two distinct types of linking and three distinct types of intersection search. These three types of intersection are then used to explain the facilitation of lexical decisions, the nature of polysemy, riddles, several production experiments by Loftus, as well as the effect of word order on meaning and paired-associate learning.J. S. Markovitch2001-05-16Z2011-03-11T08:54:38Zhttp://cogprints.org/id/eprint/1503This item is in the repository with the URL: http://cogprints.org/id/eprint/15032001-05-16ZImpairments of search behaviour in rats after haloperidol treatment, hippocampal or neocortical damage suggest a mesocorticolimbic role in cognitionIntroduction:
In view of reports that fimbria-fornix or hippocampal lesions impair working rather than reference memory in a radial maze (Olton et al., 1979) the performance of rodents with hippocampal damage was examined on a hole-board search task.
Methods:
Food-deprived animals searched for food pellets placed consistently in 4 holes of a 16-hole-board (figure 1). They were presented with 11 sessions of 10 trials/session. There were three groups of animals, - one with aspiration lesions of the hippocampus and overlying neocortex, one with damage only to the overlying neocortex and sham-controls that went through the procedure but the brain was left intact (Oades and Isaacson, 1978). Half of each group received haloperidol (0.275 mg/kg) or saline injections 15 minutes before each of the sessions 4-10.
Working memory error = a visit to a correct hole that has just been visited, and thus no longer contains a food pellet.
Reference memory error = visit to a hole that is never baited.
Results:
1/ Hippocampal damage resulted in poorer performance on both working and reference memory measures: this was unaffected by haloperidol treatment.
2/ Neuroleptic treatment also impaired the performance of the sham-controls on both measures.
3/ Animals with neocortical damage were impaired on reference mmeory measures alon, after haloperidol treatment.
Conclusions:
.The lack of a neuroleptic effect on performance after hippocampal damage suggests that this lesion does not impair performance on these two measures of memory performance through a dopaminergic mechanism.
Haloperidol impaired working memory measures in sham-controls, but only reference memory measures in the neocortical group.. The results imply that there are (at least) three separate mechanisms (i.e. meso-cortico-limbic interactions) at work here involved in shorter- and longer-term consolidation of the consequences of selective attention mechanism required to efficiently learn a search task. Oades1999-06-10Z2011-03-11T08:54:18Zhttp://cogprints.org/id/eprint/813This item is in the repository with the URL: http://cogprints.org/id/eprint/8131999-06-10ZMultistage Acquisition of Intelligent BehaviourHuman skills are acquired not by a single uniform process, but in a series of stages, as Piaget has shown. We have investigated such a sequential process by taking as an illustrative example the game of table tennis. The aims in each stage of learning are qualitatively different, and we show in detail how knowledge gained during one stage provides essential information for subsequent stages. Conclusions are drawn which may be important for artificial intelligence work generally. The question of practical implementation of a system such as discussed is considered briefly.Brian D. JosephsonH. M. Hauser2007-10-22T10:45:16Z2011-03-11T08:56:58Zhttp://cogprints.org/id/eprint/5767This item is in the repository with the URL: http://cogprints.org/id/eprint/57672007-10-22T10:45:16ZObserving birth and placentophagia affects placentophagia but not maternal behavior of virgin ratsTo determine whether observing components of periparturitional behavior affects the manifestation of those behaviors in virgin rats, virgins selected for nonplacentophagia and for the absence of spontaneous maternal behavior toward pups were exposed to stimulus rats that were giving birth, eating placenta, or eating lab chow. During observations, subjects could either eat donor placenta or just see and smell it. The subjects were tested subsequently for placentophagia and for the rate of onset of pup-induced maternal behavior. The results indicated that: (1) access to placenta in the presence of other rats led to placentophagia; (2) when such placentophagia occurred in conjunction with exposure to other rats that were giving birth or eating donor placenta, the subjects became permanent placentophages (otherwise, the subjects reverted and did not eat on subsequent placentophagia tests); (3) none of the observation conditions, regardless of the availability of placenta during observation, affected the maternal sensitization latency. The results are discussed in terms of social facilitation, exposure learning, and desensitization to exteroceptive stimuli.Dr. Mark B. Kristalkristal@buffalo.eduJ. Ken Nishita2007-10-25T10:18:52Z2011-03-11T08:56:59Zhttp://cogprints.org/id/eprint/5785This item is in the repository with the URL: http://cogprints.org/id/eprint/57852007-10-25T10:18:52ZPlacenta on pups' skin accelerates onset of maternal behaviour in non-pregnant ratsPrevious research has indicated that virgin rats (Rattus norvegicus) behave maternally (sensitize) more rapidly if kept in close proximity with pups. Since both parturient rats and a large percentage of virgin rats avidly consume placenta, we tested whether placenta and amnionic fluid, applied to the skin of the stimulus pups, would draw the female adults into closer contact with the pups and therefore hasten the onset of maternal behaviour. The results indicated that the procedure indeed shortened the maternal sensitization latency. Furthermore, this effect was not due to the wetness of the pups, to the presence of placenta in the cage, or to the adults having previously ingested placenta. Other attractive ingestibles applied to the pups' skin produced intermediate, but not significant, shortening of the maternal sensitization latency.Dr. Mark B. Kristalkristal@buffalo.eduJ.F. WhitneyL. C. Peters2001-05-16Z2011-03-11T08:54:38Zhttp://cogprints.org/id/eprint/1504This item is in the repository with the URL: http://cogprints.org/id/eprint/15042001-05-16ZTestosterone administration in chicks affects responding in the presence of task irrelevant stimulus changesIntroduction:
A series of studies have shown that circulating testosterone increases the persistence with which animals search for and select a particular visual cue to respond to (as a consequence of experience with it) - and hence incur a perseveration of response towards such cues (e.g. Rogers 1971; Andrew 1972, Archer 1976; Earley & Leonard 1978).
We tested the effect of testosterone on such attention-related mechanisms by studying the effect of intradimensionsional colour changes to cues relevant and irrelevant to an operant discrimination on continuous reinforcement learning (non-reversal shifts).
Methods:
Treatment: Chicks (20 males) were given 12.5 mg testosterone enanthate im after training on a continuous reinforcement schedule of response (CRF); 19 controls received sesame oil vehicle and 8 males and 15 females had no treatment.
Testing: Birds were given A) test sessions on day 10 and 11: whereby each session consisted of 2 minutes training, 5 minutes test then 2 minutes re-training: B) 4 types of test --(i) the negative key colour changed from red to deep blue, (ii) the positive key colour changed from pale blue to green, and (iii) both key colours changed as described, and (iv) the overhead lighting changed with the introduction of a pale red filter.
Results:
1/ Treatment did not affect CRF patterns of discriminative responding.
2/ All birds decreased their response rate after a colour change.
3/ After changes on the non-reinforced key, testosterone treated birds showed significantly less attenuation of response rate.
4/ Testosterone treatment also maintained a higher rate of response (and hence fewer reinforcements) - seen especially after a change in the negative cue or overhead lighting vs. changes in the positive cue (irrelevant changes of stimulation).
5/ Testosterone treated birds also showed a shorter latency to respond after a colour change.
6/ The female birds did not differ from the males
Conclusions:
The results support a role for testosterone in the discrimination between relevant and irrelevant stimulus changes and the persistent expression of learned sets.
The fact that responding after testosterone treatment was altered by irrelevant rather than relevant stimulus changes suggests that testosterone achieves its persistence effect by enhancing the activated set or what is at the focus of attention, rather than the inhibition of features irrelevant to the ongoing situation - these provide the reference for 'what is relevant' and changes in them disturb this mechanismR.D. Oades Messent2001-05-08Z2011-03-11T08:54:37Zhttp://cogprints.org/id/eprint/1482This item is in the repository with the URL: http://cogprints.org/id/eprint/14822001-05-08ZTypes of memory or attention ? Impairments after lesions of the hippocampus and limbic ventral tegmentumIntroduction:
An animal with an unimpaired reference memory can distinguish between alternatives that belong to a rewarded set and those that are always unrewarded. An animal with an unimpaired working memory can distinguish beween alternatives where it has been rewarded (e.g. food has been eaten, but not replaced) and those where it will still be rewarded.
Olton et al., 1979 proposed that fimbria-fornix or hippocampal lesions impairs working rather than reference memory in a radial maze. This hypothesis was tested for rats with damage to the hippocampus, limbic ventral tegmentum (VTA A10 ) and neocortex, intact and operated controls on a 16-hole-board search task.
Methods:
Food-deprived animals searched for food pellets placed consistently in 4 holes of a 16-hole-board (figure 1). They were presented with 11 sessions of 10 trials/session. There were five groups of animals, - one with aspiration lesions of the hippocampus and overlying neocortex, one with damage only to the overlying neocortex and sham-controls that went through the procedure but the brain was left intact (Oades and Isaacson, 1978) - VTA damage resulted from coagulation with a stylet in a sterotaxically implanted cannula and their controls received the cannula alone.
Working memory error = a visit to a correct hole that has just been visited, and thus no longer contains a food pellet.
Reference memory error = visit to a hole that is never baited.
Results:
1/ A reference and a working memory impairment (in terms of errors made) was recorded for animals with hippocampal or with VTA damage.
2/ The impairments were significant by session 3 and the differences amounted to more than 50% by the end of testing.
Conclusions:
.There was a striking similarity between the performances of animals with damage to the hippocampus and those with damage to the VTA (that projects to the lateral septum, entorhinal cortex and dentate gyrus. The different results obtained by Olton in the radial maze may be explained by the discrete trial testing conducted in the radial maze that contrasts with the multiple choices that an animal makes on a hole-board. Further in the current study training occurred exclusively post-operatively, while in the radial maze animals had received some preoperative training.
Both lesioned and control animals expressed preferred sequences of hole-visits. The preference was weaker in the lesioned animals but the number of changes of preference between sessions did not differ between groups. Thus it is argued that limbic and mesolimbic DA substrates are crucially involved in attentive mechanisms important to adaptive learning and the impairment is not merely one of forming and using memory.
Oades1998-06-22Z2011-03-11T08:54:12Zhttp://cogprints.org/id/eprint/705This item is in the repository with the URL: http://cogprints.org/id/eprint/7051998-06-22ZWhy robots will have emotionsEmotions involve complex processes produced by interactions between motives, beliefs, percepts, etc. E.g. real or imagined fulfilment or violation of a motive, or triggering of a 'motive-generator', can disturb processes produced by other motives. To understand emotions, therefore, we need to understand motives and the types of processes they can produce. This leads to a study of the global architecture of a mind. Some constraints on the evolution of minds are disussed. Types of motives and the processes they generate are sketched.Aaron SlomanMonica Croucher