Electroconvulsive shock (ECS) produces a loss of memory for the immediately preceding period, but also produces non-amnesic effects which seriously complicate the interpretation of behavioral results following convulsions. The results of the present investigation indicated that the retrograde amnesia produced by ECS is probably slight, but appears enhanced in passive-avoidance tasks and diminished in aversively-motivated tasks requiring movement, because of a concomitant impairment of movement-inhibiting mechanisms. If this interpretation is valid, it is extremely difficult to make quantitative estimates of the degree or temporal extent of the retrograde amnesia induced by ECS in animals. It may be possible, however, to separate memory mechanisms from movement-inhibiting mechanisms with procedures involving more localized effects upon the brain. / Thesis / Doctor of Philosophy (PhD)

Call number: LD2668 .T4 1964 L58 / Master of Science

Conventional theories of diencephalic amnesia have focused on a single thalamic region as a critical factor in the origins of anterograde amnesia. A more contemporary view is that different thalamic regions might contribute in unique ways to normal diencephalic functioning and therefore provide distinct contributions to the learning and memory. This study directly compared the effects of AT and MT lesions on a spatial pattern separation task, a spatial working memory task and a conditioned place preference task. AT lesions but not MT lesions produces deficits on the spatial working memory task on a cheeseboard. No group AT, MT or control rats acquired a conditioned place preference on the AT/MT lesion conditioned place preference task. Furthermore, this study determined the effect of systematic procedural variations on control rats in a conditioned place preference control task. The only variation that acquired a condition place preference was a separate arms conditioned place preference with one pre-exposure and three training trials. The results of this study provide new information regarding the role of thalamic lesions in spatial memory and suggests a revision of the current theories regarding learning and memory to incorporate the thalamic involvement that has been highlighted

This thesis investigated the characteristics of childhood memories that remain accessible over the whole life span. On the assumption that one of the primary purposes of autobiographical memory is its adaptive function, it was hypothesised that, in order to fulfil this function, autobiographical memories must include an affective component. That is, each memory will consist of a record of an experienced event together with the accompanying emotion so as to mediate an appropriate behavioural response in similar future circumstances. For the same reason, it was also predicted that, as a person grows older, selected childhood memories will still retain their emotionality, vividness and personal importance. A detailed analysis of the nature of childhood memories was undertaken and evidence to support these hypotheses was sought in three separate studies. In Study 1, a structured interview was used and 109 people aged between 21 and 91 years were asked to free recall memories drawn from within three - year periods of childhood from birth to 18 years. Subjects' ratings were used to explore the characteristics of these memories and the effects of age encoding subject age and subject gender were systematically examined. In contrast with previous research, it was found that 83 % of subjects could recall memories from below three years of age. Uniformly high ratings of emotionality showed that the affective component, as predicted, was high across all encoding. ages and showed no decline with subject age. Ratings of clarity and realism were also unaffected by subject age. The incidence and vividness of sensory imagery increased with age of encoding, but, again, did not decline with subject age. Although most vivid memories involved imagery, 15%of subjects sometimes claimed to recall vividly without imaging. These findings suggest that the affective component may have been contributing to overall vividness. Study 2 using, cued recall, compared latency of response for emotion cued words and object cued words and also used ratings to examine the characteristics of the retrieved memories. Memories were retrieved Faster to object cues but these memories were still rated high in emotionality. Memories retrieved to emotion cues, although slower to access, were rated as more important, more emotional, more unusual and more frequently recalled. Cue type was therefore shown to be a powerful factor in determining accessibility, overriding other memory characteristics. Although in Studies 1 and 2 subjects selected their own memories, Study 3 tested the retention of details of early experience of school life as designated by the researcher. It was found that detailed memories could still be recalled even in old a`e and that the rate of forgetting declined steadily with age This evidence of persisting retention of early childhood experience is consistent with the view that such memories serve a functional role in that they are an integral part of the 3 individual's self history and developing self concept. The research provides a substantial body of data detailing, the topics recalled From different periods of childhood and the nature of the memories and charts the remarkable stability of these memories across the life span.

Spontaneous co-speech hand gestures robustly affect learning and memory. Viewing or producing hand gestures during conversation facilitates the encoding, consolidation, and retention of the information in speech. Despite these effects, the cognitive and neural mechanisms supporting this relationship remains unknown. In Experiment 1, I explored the memory mechanisms supporting hand gesture by working with patients with damage to their hippocampus and thus their declarative memory system. Participants engaged in discourse tasks that disproportionately engaged the hippocampus. I found that patients gestured less overall than healthy comparisons across all tasks, suggesting that the hippocampus indeed plays a role in gesture production. In order to test whether non-declarative memory supports gesture production as well, Experiment 2 directly manipulated features of memory representations (both visual and motor) to determine what would guide the form of gesture when participants later explained their experiences. On three visits, amnesic patients, healthy comparison and brain-damaged comparison groups completed a Tower of Hanoi task, involving moving disks between pegs following a set of rules. On each visit, participants completed the task with different visual and motor information. Comparisons' gestures tended to reflect both visual and motor experience, while patients' gestures tended to rely more heavily on their motor experiences. This suggests that gesture may be supported by non-declarative memory as well, particularly in the absence of a declarative memory for what is being discussed. To directly test which properties of gesture facilitate learning, Experiment 3 examined how gesture affected the learning of novel labels for common, everyday objects. I again worked with patients with hippocampal amnesia, who are severely impaired in the learning of new words, along with healthy and brain-damaged comparisons. Participants were exposed to novel word-object pairing that either was learned with a gesture or not. For the gestured-with trials, the gesture was either viewed and then produced by the participant or passively viewed, allowing me to determine if production of a gesture was necessary for learning. After adequately learning all the word-object pairings, there was a 30-minute delay followed by a free recall and object identification task. Both comparison groups showed good learning of the words regardless of whether they were learned with gesture. The amnesic patients performed poorly on the recall task. On the object identification task, they were significantly more likely to identify the label-object pairing if the pairing had been learned with gesture. This benefit was only seen for those learned by producing gesture. For the pairings learned without gesture and the pairings learned with only viewing gesture, the patients were at chance. These findings demonstrate that gesture can help rescue hippocampal amnesics’ ability to bind labels with objects, and furthermore suggest that the self-production of gesture is critical for learning. These findings are the first to demonstrate a link between gesture and memory systems. Experiments 1 and 2 demonstrate that gesture can reflect information from both declarative and non-declarative memory. Experiment 3 demonstrates that the link between gesture and non-declarative memory can be exploited to facilitate learning in patients with memory impairment. By understanding how memory and language interact we will be able to exploit this interaction to benefit memory and language more generally.

The overarching goal of this thesis was to examine aspects of childhood amnesia in children, adolescents, and adults, and to evaluate theoretical explanations for the phenomenon. The research addressed three main questions. First, at what age does the boundary of childhood amnesia occur in adults, and what is the shape of the boundary? Second, is it possible for children to verbally express preverbal aspects of their memories after a 6-year delay? Third, is maternal narrative style during early childhood related to the age of adolescents� earliest autobiographical memories? In Experiment 1A, I examined whether the way in which we ask adults to sample their memories alters estimates of the offset of childhood amnesia. Independent groups of adults were asked to describe and date one memory from any time in their lives associated with each of six cue words (Lifespan Condition), one childhood memory associated with each of six cue words (Childhood Condition), or their earliest memory associated with each of six cue words (Cued Earliest Condition). A fourth group of adults was asked to describe and date their six earliest memories (Uncued Earliest Condition). As predicted, participants in the Cued Earliest and Uncued Earliest Conditions reported earlier memories than participants in the Childhood Condition, who in turn reported earlier memories than participants in the Lifespan Condition. Consistent with prior research, when adults were asked to report their earliest memories, with or without the use of cue words, the mean age of the earliest memory reported was between 3 and 4 years. In Experiment 1B, I examined the distribution of the early memories reported by six individual adults by asking them to report all the memories that they could recall from each year of childhood, until they had reported at least their 20 earliest memories. When the number of memories recalled was plotted as a function of age at event, the distributions looked like step functions, with the step occurring at ages 4-6 years. Participants also reported some early memories for events that occurred before this age. In Experiment 2, I examined children�s and parents� verbal and non-verbal recall for a specific event - the Magic Shrinking Machine - after a 6-year delay. The children were aged 27-51 months when they originally played with the machine. After a 6-year delay, nine of 46 children and 26 of 42 parents verbally recalled the event. There were no age-related differences in the amount or accuracy of the information that participants reported about the event. When children�s reports were compared to their task-relevant vocabulary measured at the time of the event, there were just two instances in which a child used a word to describe the event that had not been part of his or her productive vocabulary at the time of the event. Children showed no non-verbal recall of the event, relative to a group of age-matched controls. In Experiment 3, I tested the hypothesis that the way that parents talk about the past with their children during early childhood will influence the age of these children�s earliest autobiographical memories when they are older. Conversations about past events between 17 mother-child dyads were recorded on multiple occasions between the children�s 2nd and 4th birthdays. When these children were between the ages of 12-13 years, they were asked to describe their earliest autobiographical memory. Adolescents whose mothers used a greater ratio of elaborations to repetitions when discussing the past with their child during early childhood had earlier first memories than did adolescents whose mothers used a smaller ratio of elaborations to repetitions. The present findings on adults� earliest memories are consistent with a two-stage model of childhood amnesia. Theories that draw on multiple cognitive developments provide a more complete account of childhood amnesia than theories that focus on a single developmental milestone. I propose that neurological maturation and language acquisition set the stage for subsequent language-related developments that contribute to the emergence of autobiographical memory and, ultimately, the offset of childhood amnesia.

The work in this dissertation aims to describe a simple new test for odor-recognition memory in rats that can be readily performed and results in an easily observable and lasting form of memory. This test has allowed for the demonstration of ethanol-induced retrograde memory impairments in rats when ethanol is administered during both the consolidation and reconsolidation phases of memory encoding. The observation that a high-dose of ethanol can cause retrograde memory impairments when administered immediately or within hours after learning has taken place is an original finding that may have implications for understanding human blackouts. Furthermore, the finding that ethanol can disrupt the reconsolidation of a previously consolidated memory has not been previously established. It is also demonstrated that caffeine can prevent ethanol’s memory impairing effects, a result that contributes a new piece of evidence for caffeine’s effects on the learning and memory process. This effect has been further investigated mechanistically and attributed to caffeine’s dual role as a phosphodiesterase type 5 inhibitor and adenosine A2A antagonist. Neither of these mechanisms alone appear to be sufficient enough to prevent the retrograde memory impairments seen with ethanol. It is hoped that this test and our findings will prove useful for future investigations into the effects of ethanol on learning and memory and the human phenomenon of alcohol-induced blackouts. / text

The nonrecurring-items delayed nonmatching-to-sample (DNMS) task is an integral part of contemporary monkey models of brain-damage-produced amnesia. This thesis began the development of a comparable rat model of brain-damage-produced amnesia. First, a DNMS task for rats was designed by adapting key features of the monkey task. Then, the rat DNMS task was studied in three experiments; each assessed the comparability of the rat DNMS task to the monkey DNMS task. Experiment 1 determined the rate at which the rat DNMS task is learned and the asymptotic level at which it is performed, Experiment 2 assessed the memory abilities that it taps, and Experiment 3 investigated the brain structures that are involved i n its performance. In Experiment 1, rats were trained on the DNMS task and their performance was assessed at retention delays of 4, 15, 60, 120, and 600 s. All of the rats learned the DNMS task, and their performance was comparable to that commonly reported for monkeys in terms of both the rate at which they acquired the nonmatching rule at a brief retention delay and their asymptotic accuracy at delays of up to 120 s. These results establish that rats can perform a DNMS task that closely resembles the monkey DNMS task and that they can approximate the level of performance that is achieved by monkeys. Experiment 2 examined the effects of distraction during the retention delay on the DNMS performance of rats. Rats were tested at retention delays of 60 s. On half of the trials, the rats performed a distraction task during the retention delay; on the other half, they did not. Consistent with findings from monkeys and humans, distraction during the retention delay disrupted the DNMS performance of rats. This suggests that similar memory abilities are involved in the DNMS performance of rats, monkeys, and humans. Experiment 3 investigated the effects of separate and combined bilateral lesions of the hippocampus and the amygdala on DNMS performance in pretrained rats. Rats were tested both before and after surgery at retention delays of 4, 15, 60, 120, and 600 s. Each experimental rat received bilateral lesions of the hippocampus, amygdala, or both. There were no significant differences among the three experimental groups, and the rats in each of the three experimental groups were significantly impaired, in comparison to no-surgery control rats, only at the 600-s delay. In contrast, rats that had sustained inadvertent entorhinal and perirhinal cortex damage during surgery displayed profound D N M S deficits. These results parallel the results of recent studies of the neural basis of DNMS in monkeys. They suggest that, in contrast to one previously popular view, neither the hippocampus nor the amygdala play a critical role in the DNMS of pretrained animals and that the entorhinal and perirhinal cortex are critically involved. On the basis of these findings, it appears that the rat DNMS task may prove to be a useful component of rat models of brain-damage-produced amnesia. This conclusion is supported by the preliminary results of several experiments that are currently employing the task.

The overarching goal of this thesis was to examine aspects of childhood amnesia in children, adolescents, and adults, and to evaluate theoretical explanations for the phenomenon. The research addressed three main questions. First, at what age does the boundary of childhood amnesia occur in adults, and what is the shape of the boundary? Second, is it possible for children to verbally express preverbal aspects of their memories after a 6-year delay? Third, is maternal narrative style during early childhood related to the age of adolescents� earliest autobiographical memories? In Experiment 1A, I examined whether the way in which we ask adults to sample their memories alters estimates of the offset of childhood amnesia. Independent groups of adults were asked to describe and date one memory from any time in their lives associated with each of six cue words (Lifespan Condition), one childhood memory associated with each of six cue words (Childhood Condition), or their earliest memory associated with each of six cue words (Cued Earliest Condition). A fourth group of adults was asked to describe and date their six earliest memories (Uncued Earliest Condition). As predicted, participants in the Cued Earliest and Uncued Earliest Conditions reported earlier memories than participants in the Childhood Condition, who in turn reported earlier memories than participants in the Lifespan Condition. Consistent with prior research, when adults were asked to report their earliest memories, with or without the use of cue words, the mean age of the earliest memory reported was between 3 and 4 years. In Experiment 1B, I examined the distribution of the early memories reported by six individual adults by asking them to report all the memories that they could recall from each year of childhood, until they had reported at least their 20 earliest memories. When the number of memories recalled was plotted as a function of age at event, the distributions looked like step functions, with the step occurring at ages 4-6 years. Participants also reported some early memories for events that occurred before this age. In Experiment 2, I examined children�s and parents� verbal and non-verbal recall for a specific event - the Magic Shrinking Machine - after a 6-year delay. The children were aged 27-51 months when they originally played with the machine. After a 6-year delay, nine of 46 children and 26 of 42 parents verbally recalled the event. There were no age-related differences in the amount or accuracy of the information that participants reported about the event. When children�s reports were compared to their task-relevant vocabulary measured at the time of the event, there were just two instances in which a child used a word to describe the event that had not been part of his or her productive vocabulary at the time of the event. Children showed no non-verbal recall of the event, relative to a group of age-matched controls. In Experiment 3, I tested the hypothesis that the way that parents talk about the past with their children during early childhood will influence the age of these children�s earliest autobiographical memories when they are older. Conversations about past events between 17 mother-child dyads were recorded on multiple occasions between the children�s 2nd and 4th birthdays. When these children were between the ages of 12-13 years, they were asked to describe their earliest autobiographical memory. Adolescents whose mothers used a greater ratio of elaborations to repetitions when discussing the past with their child during early childhood had earlier first memories than did adolescents whose mothers used a smaller ratio of elaborations to repetitions. The present findings on adults� earliest memories are consistent with a two-stage model of childhood amnesia. Theories that draw on multiple cognitive developments provide a more complete account of childhood amnesia than theories that focus on a single developmental milestone. I propose that neurological maturation and language acquisition set the stage for subsequent language-related developments that contribute to the emergence of autobiographical memory and, ultimately, the offset of childhood amnesia.

Conventional theories of diencephalic amnesia have focused on a single thalamic region as a critical factor in the origins of anterograde amnesia. A more contemporary view is that different thalamic regions might contribute in unique ways to normal diencephalic functioning and therefore provide distinct contributions to the learning and memory. This study directly compared the effects of AT and MT lesions on a spatial pattern separation task, a spatial working memory task and a conditioned place preference task. AT lesions but not MT lesions produces deficits on the spatial working memory task on a cheeseboard. No group AT, MT or control rats acquired a conditioned place preference on the AT/MT lesion conditioned place preference task. Furthermore, this study determined the effect of systematic procedural variations on control rats in a conditioned place preference control task. The only variation that acquired a condition place preference was a separate arms conditioned place preference with one pre-exposure and three training trials. The results of this study provide new information regarding the role of thalamic lesions in spatial memory and suggests a revision of the current theories regarding learning and memory to incorporate the thalamic involvement that has been highlighted