What is the role of the hippocampus and associated areas such as the entorhinal cortex and medial septum in spatial navigation: Do theta oscillations have a significant effect on spatial navigation and could this shed light on the underlying neural mechanisms ?
The hippocampus has been associated with memory formation and consolidation, through lesions studies of bilateral medial temporal lobectomy patients, such as the famously amnesic H.M. In 1971 with the discovery of place cells by O’Keefe and Dostrovsky, spatial navigation was recognised as one of the primary roles of the hippocampus, with their 1978 book ‘The Hippocampus as a Cognitive Map' O’Keefe and Nadel’s hypothesis has since commanded great influence in the field.
The term ‘place cell’ usually refers to pyramidal neurons in the hippocampus that show increased activity when an animal, generally a rodent, is in a particular location on an experimental track or arena. The regions within which the cells fire are known as place fields, it is thought that place cells are active in response to sensory cues and particularly to complex stimuli. This suggests place cell function is dependent on sensory input and integration. Counterintuitively, place cell activation is not static to any objective or relative place field locations, as when transferred to a novel environment any particular place cell may be activated by a completely unrelated place field or ‘remapped’. This suggests the place cells integrate information with a contextual component and a metric component relating sensory and distance data. (Jeffery, 2007)
By examining areas with cortical inputs to the hippocampus Moser and others in 2005 discovered another type of cell in the dorsomedial entorhinal cortex (dME...
... middle of paper ...
...tory interference model; based on the difference and interference of theta phase between the soma and dendritic processes which results in periodic spatial activity derived from the temporal signal (Burgess N, Barry C, O'Keefe 2007 and Giacomo, Zilli 2007) and the attractor model; based on network dynamics, with the reciprocal firing of grid cells as the basis of periodicity. As the importance of theta cannot yet be effectively determined in humans elucidating the mechanism of grid periodicity will have long lasting implications on the direction of research and may require a critical rethinking of many of the currently accepted models. The chosen papers explore this in two ways: the first paper by examines the effects of the removal of theta on grid cell periodicity and the second seeks to determine if the presence of theta is necessary for normal grid cell activity.
Eichenbaum, H., Otto, T., & Cohen, N. J. (1992). The hippocampus—what does it do? Behavioral
Spatial learning is the ability of an organism to memorize their environment and to use this information to navigate within it. Boal et al. (2000) notes that this type of learning has been demonstrated by other inverts. It has been demonstrated that through spatial learning, octopuses can remember where they have been and have an understanding of distance, likely by utilizing a cognitive map and a working memory (Boal et al., 2000; Mather, 2006; Mather & Kuba, 2013; Stolzenburg, 1993). They also have the ability to orient themselves in space, even when displaced by experimenters and have been shown to use moving landmarks to do so (Alves et al., 2008; Boal et al., 2000; Mather, 2006; Mather & Kuba, 2013). These abilities allow them to navigate many different areas and consistently find their way home. Octopuses often forage far from home and their paths to and from the den do not usually overlap nor do they use the same route multiple times, indicating that they know where they have been and that food will no longer be available there (Boal et al., 2000; Hvorency et al., 2007; Mather, 2006; Mather & Kuba,
The orbitofrontal cortex is associated with the limbic system including the amydala, and the dorsolateral prefrontal cortex. Association to the limbic system includes the connection to insular cortex, the parahippocampal regions and the hippocampus (Cavada et al., 2000). The limbic system influences the control of behaviour and emotions in an individ...
Hemineglect is present when there is damage to the dorsal/ where visual pathway in the brain which leads from the occipital lobe of the brain to the parietal lobe. The ‘where visual pathway’ is concerned with constructing three dimensional representations of the environment and helps our brain to navigate where things...
Discussed by Cipolotti & Bird (2006), LTM impairments can lead to anterograde and retrograde amnesia if the medial temporal lobe (MTL) is damaged bilaterally. Specifically, the two most important types of LTM related to anterograde and retrograde amnesia are episodic and semantic memories. Conversely, many researchers have long debated the true functions of the hippocampus and have allowed two theories to emerge. The standard model of consolidation (SMC) assumes that the hippocampus is important in consolidating LTM, while the multiple trace theory (MTT) argues that information is encoded by specific memory traces by the hippocampus. These two theories help further explain the vast functions of the hippocampus.
According to these two cases, these inspire us to understand that the hippocampus is an important brain region that is used for converting short-term memory into long-term memory.
Kanske, P., Heissler, J., Schönfelder, S., Forneck, J., & Wessa, M. (2013). Neural correlates of
Technology and the Brain As a college student, using the internet and technology is a daily task. Everything you need for your classes: schedules, homework, quizzes, and even tests are all online. The debate on technology and the brain suggests that technology may have an effect on the brain, effect multi-tasking, and cause addiction. Brain Activity
The question then becomes whether declarative and non-declarative memory are in fact separate or different manifestations of the same neural process. From research on H.M., we find evidence for the existence of a declarative memory system that is independent of non-declarative memory and other forms of intelligence. H.M. had the capacity to hold information in his head for a period of time, suggesting that his working memory was intact (Squire and Wixted, 2011). Further evidence that not all memory is the same is the fact that H.M. acquired a motor skill despite not being able to remember actually learning the skill, thus showing the difference between episodic and semantic memory. Amnesiacs are able to acquire the perceptual skill of reading mirror-reversed words at a normal rate compared to controls (Cohen and Squire, 1980), demonstrating that the ability to learn new perceptual skills also remains intact. Of the forms of non-declarative memory, procedural memory involves the cerebellum, motor cortex, and basal ganglia (General Intro the Neurobiology…). Thus, non-declarative memory can, in a way, be seen as a more primitive form of memory that is not acquired through the integration and consolidation of neural events in the medial temporal lobe, but rather through learned associations outside of the
In the field of Psychology you can find an abundance of mental disorders that can have an affect on people all throughout the world. Out of all the mental disorders that can be found around the world, some of them are more well-known and more widespread than others. The following disorders could be described as being well-known and widespread disorders: depression, bi-polar disorder, Alzheimer's, and OCD, which could also be called Obsessive Compulsive Disorder. All of these mental disorders can be very dangerous and possibly deadly if people don't receive the proper care in order to be able to contain these disorders. Out of these very dangerous and possibly deadly disorders, I believe that Alzheimer's is the most interesting disorder. I think that Alzheimer's is the most interesting disorder, because I think we have the least about of knowledge of the Alzheimer's disorder. As a society we still to this day don't have a cure that totally stops this disorder.
Hippocampus plays an important job in the formation of new memories about experienced events such as the episodic or the autobiographical memory. It is also a part of larger medial temporal lobe memory system responsible for general declarative memory. General declarative memory is a type of memories that can be explicitly verbalized. If damage to hippocampus occurs only in one hemisphere, our brain can still retain near-normal memory functioning. But even so the hippocampus is damage; some types of memory such as abilities to learn new skills will not be affected. The reason is because, some abilities depends on different types of memory and different regions of the brain such as procedural memory. Hippocampus also plays role in spatial memory and navigation. Many hippocampal neurons have “place fields” and the discovery of place cells in 1970’s led to the theory that hippocampus might act as cognitive
Most of the body’s functions such as, thinking, emotions, memories and so forth are controlled by the brain. It serves as a central nervous system in the human body. The mind is the intellect/consciousness that originates in the human brain and manifests itself in emotions, thoughts, perceptions and so forth. This means that the brain is the key interpreter of the mind’s content. Jackson and Nagel seem to resist identifying what we call “mental events” with brain events, for different reasons, while J.J.C. Smart takes the opposing view.
Collective memory is the cultural memory (? ) or the remembered history of a community: “Anyone who during today fixes his eyes on tomorrow must preserve yesterday from oblivion by grasping it through memory” (Assmann 2011: 17). Collective memory is the way groups form memories out of a shared past to create a common identity. The memory of a group is a construction, or reconstruction, of the past. Through the approach of collective memory we can distinguish a cultural sphere that combines tradition, awareness of history, myth in action, and self-definition. This cultural sphere is constantly subject to a vast range of historically conditioned changes (Assmann 2011: 10). Collective memory is the structures that underlie all myths and histories without any distinction between them. The past that is fixed and internalized is myth, whether it is fact or fiction (Assmann 2011: 59). Collective memory can be expressed through a variety of different medias, e.g. festivals, rituals, liturgy, symbols, flags, memorial places, museums, cultural artifacts, as well as oral and written narratives, like myths, prophecies, law material, biographies and perceived historical accounts (Van Seters 2012: 54). The memories are specifically designed to recall events in the history of the collective.
[online] Available at: http://www.livescience.com/22665-nervous system.html [Accessed: 1 Oct 2013]. Reece, J. 2012. The. Campbell biology. San Francisco, CA. -.
One form of skepticism is the skepticism about the external world — the theory that we can never have any knowledge about the external world, even the existence of it; the theory also suggests that we can only know the internal world which is our own mind(Carr, lecture 8). For example, a skeptic may say “we don’t know if we have hands because what we see may be illusions” or “we don’t know if we are not brains in vats experiencing a huge hallucination”. Among many philosophers who attempt to defeat skepticism about the external world, Putnam argues that “we are brains in vats”(BIVs) is always self-falsifying because brains in vats do not satisfy the necessary condition for being able to refer to the