Segmentation of experience and episodic memory across species

How continuous ongoing perceptual experience is processed by the brain and mind to form unique episodes in memory is a key scientific question. Recent work in Psychology and Neuroscience has proposed that humans perceptually segment continuous ongoing experience into meaningful units, which allows the successful formation of episodic memories. Despite accumulating work demonstrating that non- human animals also display a capability of episodic-‘like’ memory, whether non-human animals segment continuous ongoing experience into ‘meaningful’ episodic units is a question that has not been fully explored. Hence, the main goal of the research in this thesis aims to address whether a comparable segmentation process (or processes) of continuous ongoing experience occurs for non-human animals in their formation of episodic-like memory, as it does for humans in their formation of episodic memory. Chapter 2 argues that, similarly to humans, rats can use top-down like prediction-error processing in segmenting for subsequent memory to guide behaviour in an episodic-like spontaneous object recognition task. Chapter 3 suggests that mice readily incorporate conspecific-contextual information using episodic-like memory processing, indicating that conspecifics can act as a segmentation cue for non-human animals. Chapter 4 highlights that humans and rodents may similarly segment continuous ongoing experience during turns made around spatial boundaries. Chapter 5 argues that individual place cells can represent content of episodic nature, with the theoretical implication of this being discussed in relation to episodic memory. Thus, the results presented in this thesis, as well as re-interpretation of previous literature, would argue in favour of non-humans segmenting their experience for episodic-like memory. Finally, the evidence is evaluated in the context of whether episodic-like memory in non-human animals is simply just episodic memory as experienced in humans

Becoming One with the Image

The primary concern of Becoming One with the Screen is the question of how experience is integrated into the general unfolding of actuality as an imagistic process. It deals with the problem though the experience of spectatorship in cinema. We present the experience of participating in a film screening as a relational and associative process in order to undo the dualistic spectator/screen relationship reflective of the subject/object relation. And radiating outwards from this problem, memory looms large as explicatory of the integrative process. As such, we examine the concept‐cluster of words surrounding memory not only to (re)contextualize the discourse on memory but to tie it to the historical tradition and deal with the complementary concepts of Faciality and The Fold from the point of view of imagistic thought and memory. Central to the discussion will be the process of adumbration by which the Many become One as the perpetuum mobile of the eventual continuity of change in actuality as being. We shall advance that the façade of becoming actual of the world as a moving imagistic front as the perception of the integrated affirmation of being one with the image world. Key Words: Memory, immanence, fold, faciality, spectatorshi

Spontaneous Firing of Sensory Neurons Modulates the Gain in the Downstream Circuit of a Simple Olfactory System

In locusts and other insects, odorants are transduced into electrical signal by the olfactory receptor neurons and transmitted to central circuits for further processing. Previous studies have shown that exogenous variables (e.g., flow rates, humidity, temperature, odor mixtures, etc.) can influence the responses of the sensory neurons and therefore modulate the central circuits. However, how the sensory neuron activity is manipulated to achieve adaptive gain control in the following circuit is yet to be understood. It is possible that the magnitude of the stimulus-evoked response in the receptor neurons, their spontaneous activity, or both of these factors can change how information about a chemical cue is processed downstream. To this end, I studied the effects of modulating two different factors on the olfactory system (flow rate and relative humidity) at four levels of the olfactory system: individual olfactory receptor neurons (first-order neurons), the whole antenna (electroantennogram recordings), individual projection neurons in the antennal lobe of the brain (second-order neurons), and population antennal lobe activity as assayed by local field potential recordings in the mushroom body. We found that flow rate changes altered the magnitude of the stimulus-evoked responses in the antenna without altering the spontaneous activity levels. Whereas, changes in the relative humidity elicited a decrease in both response magnitude and baseline activity. Intriguingly, only the humidity modulation experiments brought about significant compensatory change in the spontaneous and odor-evoked activity of the second-order neurons in the antennal lobe. Therefore, our data and analysis suggest that baseline activity of receptor neurons seems to play a key role in adapting the gain of the locust brain’s central circuit

A Review of Evolution, Behavior, and Vision with an Experimental Evolution Study on Color Vision in Drosophila melanogaster

The first chapter of this thesis is to take a piece by piece look at the factors that contributed to the experimental evolution study that will be discussed in Chapter 2. Behavior, how that can affect experimental studies, and how biases can affect sensory systems and preference in subject species. Specifically visual sensory systems are described in detail, from the possible evolutionary histories, to major components that contribute to eye structure, form, and/or abilities. We discuss how to define color vision, and what are the prerequisites for color vision in species

Brain Responses Track Patterns in Sound

This thesis uses specifically structured sound sequences, with electroencephalography (EEG) recording and behavioural tasks, to understand how the brain forms and updates a model of the auditory world. Experimental chapters 3-7 address different effects arising from statistical predictability, stimulus repetition and surprise. Stimuli comprised tone sequences, with frequencies varying in regular or random patterns. In Chapter 3, EEG data demonstrate fast recognition of predictable patterns, shown by an increase in responses to regular relative to random sequences. Behavioural experiments investigate attentional capture by stimulus structure, suggesting that regular sequences are easier to ignore. Responses to repetitive stimulation generally exhibit suppression, thought to form a building block of regularity learning. However, the patterns used in this thesis show the opposite effect, where predictable patterns show a strongly enhanced brain response, compared to frequency-matched random sequences. Chapter 4 presents a study which reconciles auditory sequence predictability and repetition in a single paradigm. Results indicate a system for automatic predictability monitoring which is distinct from, but concurrent with, repetition suppression. The brain’s internal model can be investigated via the response to rule violations. Chapters 5 and 6 present behavioural and EEG experiments where violations are inserted in the sequences. Outlier tones within regular sequences evoked a larger response than matched outliers in random sequences. However, this effect was not present when the violation comprised a silent gap. Chapter 7 concerns the ability of the brain to update an existing model. Regular patterns transitioned to a different rule, keeping the frequency content constant. Responses show a period of adjustment to the rule change, followed by a return to tracking the predictability of the sequence. These findings are consistent with the notion that the brain continually maintains a detailed representation of ongoing sensory input and that this representation shapes the processing of incoming information

A Semi-Supervised Approach for Kernel-Based Temporal Clustering

Temporal clustering refers to the partitioning of a time series into multiple non-overlapping segments that belong to k temporal clusters, in such a way that segments in the same cluster are more similar to each other than to those in other clusters. Temporal clustering is a fundamental task in many fields, such as computer animation, computer vision, health care, and robotics. The applications of temporal clustering in those areas are diverse, and include human-motion imitation and recognition, emotion analysis, human activity segmentation, automated rehabilitation exercise analysis, and human-computer interaction. However, temporal clustering using a completely unsupervised method may not produce satisfactory results. Similar to regular clustering, temporal clustering also benefits from some expert knowledge that may be available. The type of approach that utilizes a small amount of knowledge to “guide” the clustering process is known as “semi-supervised clustering.” Semi-supervised temporal clustering is a strategy in which extra knowledge, in the form of pairwise constraints, is incorporated into the temporal data to help with the partitioning problem. This thesis proposes a process to adapt and transform two kernel-based methods into semi-supervised temporal clustering methods. The proposed process is exclusive to kernel-based clustering methods, and is based on two concepts. First, it uses the idea of instance-level constraints, in the form of must-link and cannot-link, to supervise the clustering methods. Second, it uses a dynamic-programming method to search for the optimal temporal clusters. The proposed process is applied to two algorithms, aligned cluster analysis (ACA) and spectral clustering. To validate the advantages of the proposed temporal semi-supervised clustering methods, a comparative analysis was performed, using the original versions of the algorithm and another semi-supervised temporal cluster. This evaluation was conducted with both synthetic data and two real-world applications. The first application includes two naturalistic audio-visual human emotion datasets, and the second application focuses on human-motion segmentation. Results show substantial improvements in accuracy, with minimal supervision, compared to unsupervised and other temporal semi-supervised approaches, without compromising time performance

Song Rhythm Development in Zebra Finches

This dissertation investigates song-rhythm learning in songbirds. Songbirds have been studied extensively in mechanistic investigations into the sensorimotor underpinnings of the cultural transmission of learned vocalizations. While several studies identified forebrain song-system neurons that generate rhythmic song patterns, we know little about how song rhythms are learned. The first part of the dissertation describes methods for detecting and analyzing birdsong rhythm patterns, and demonstrates their utility for identifying the role of song rhythms in social interactions. Results suggest that rhythm plasticity in zebra finch song may provide a potential vehicle for communication. Controlled song-learning experiments further found that developing zebra finches more readily incorporated a new song element when the tutored rhythm was unchanged, suggesting that a rhythmic framework is established during song learning. An updated schema of the song imitation process is proposed which situates sequence learning within a rhythmic framework. Finally, the role of striatal dopamine in song-mediated social cohesion in zebra finches was identified. Taken together, the dissertation’s findings lay a foundation for future explorations of rhythm in vocal learning and communication

Modulation of lateralised responses to primary affect

Do we use one cerebral hemisphere or both to process positive and negative emotions? Is it more physiologically economical for the brain to initiate responses to both types of primary affect from a unilateral locus, or does our readiness to react to emotional stimuli depend on the differential contribution of each hemisphere based on the approach or avoidance behaviours positive and negative affect elicit? This thesis is concerned with these questions that have so far remained unanswered even though they form a key part of emotional perception research. The behavioural literature has provided evidence for both unilaterally (right hemisphere) and bilaterally derived responses to different types of emotional stimuli, with the directionality of response patterns changing depending on stimulus type and task demands. The neuroimaging literature has addressed whether there is a functional need for the lateralised processing of basic emotional stimuli by mapping subcortical and cortical emotional attention networks, specific to different variants of only negative affect (i.e. fear, sadness). How this subcortically originating lateralisation manifests into observable behaviour however still remains to be established. This research therefore posits that hemispheric lateralisation may be a modulated process, and aims to explore how this modulation guides the directionality of our behavioural responses to primary affect. The thesis introduces a novel methodology that provides the first evidence of the modulation of emotional lateralisation by establishing a behavioural paradigm that can effectively investigate hemispheric lateralisation through measures of response efficiency. The thesis further investigates whether subcortically originating lateralisation may be inferred through its resulting behavioural response, by examining visual field asymmetries in responses to positive and negative affect through nasally and temporally viewed stimuli. Additionally, the thesis considers the modulating properties of contextual emotion-enhancing features of facial expressions such as direct vs. averted gaze and the presence of looming sounds on behavioural responses to negative affect, and also investigates whether individual variability in anxiety levels translates into lateralised responses to affect. Findings from the present thesis suggest that lateralisation is not a sustained, static phenomenon, but in fact a dynamic, modulated process that depends on subtle stimulus-contextual elements to subsequently translate into observable response