The hippocampus, memory, and spatial function

2020 ◽  
pp. 260-362
Author(s):  
Edmund T. Rolls
Keyword(s):  
Episodic Memory ◽  
Neuronal Network ◽  
Attractor Network ◽  
Spatial Function ◽  
Computational Operation ◽  
Recurrent Collateral ◽  
Spatial View ◽  
The Brain ◽  
Temporal Representations

The hippocampal system provides a beautiful example of how different classes of neuronal network in the brain work together as a system to implement episodic memory, the memory for particular recent events. The hippocampus contains spatial view neurons in primates including humans, which provide a representation of locations in viewed space. These representations can be combined with object and temporal representations to provide an episodic memory about what happened where and when. A key part of the system is the CA3 system with its recurrent collateral connections that provide a single attractor network for these associations to be learned. The computational generation of time, encoded by time cells in the hippocampus, is described, and this leads to a theory of hippocampal replay and reverse replay. The computational operation of a key part of the architecture, the recall of memories to the neocortex, is described.

Intermittent behavior in the brain neuronal network in the perception of ambiguous images

2017 ◽  
Author(s):  
Alexander E. Hramov ◽  
Maria K. Kurovskaya ◽  
Anastasiya E. Runnova ◽  
Maxim O. Zhuravlev ◽  
Vadim V. Grubov ◽  
...  
Keyword(s):  
Neuronal Network ◽  
Intermittent Behavior ◽  
The Brain

Consciousness Emanates from the Neuronal Network of Coordination, A Fact Endorsed by Preserved Consciousness in Focal Ischemic Infarctions

2021 ◽  
Vol 19 (3) ◽  
pp. 17-25
Author(s):  
Dr. Sohail Adnan ◽  
Dr. Mubasher Shah ◽  
Dr. Syed Fahim Shah ◽  
Dr. Fahad Naim ◽  
Dr. Akhtar Ali ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Neuronal Network ◽  
Brain Activity ◽  
Cross Sectional Study ◽  
Difficult Problem ◽  
Altered Consciousness ◽  
Cross Sectional ◽  
Consciousness Disorder ◽  
The Right ◽  
The Brain

Background: Consciousness has remained a difficult problem for the scientists to explore its relationship to the brain activity. This is the first paper that presents the significance of focal areas of the cerebral cortex for consciousness. Objectives: To determine if consciousness is produced by the activity of the whole brain or one of its focal areas. Methods: We have performed a prospective cross-sectional study in eighty patients of acute ischemic stroke. The neurovascular territory of the middle cerebral artery (MCA) was sectioned into four similar areas. The association of any of these focal areas to consciousness was observed after their dysfunction with ischemic strokes. Results: Of the eighty patients, 57.5 % were males and 42.5 % were females. Mean age was 63 years ± 7 SD. The righthanded patients were 90 % (72) of the whole sample. Focal areas of the right MCA were generally less prone to consciousness disorder. Average statistics of the focal infarctions of the right MCA showed no tendency for consciousness disorder on the Glasgow coma scale (GCS) [Mean GCS of all focal areas; 14.5, SD; 0.71, 95 % CI; 14.27 to 14.72, P= 0.0000004]. Altered consciousness with focal infarctions of the territory of left MCA was also less likely [Mean GCS of all focal areas; 14.2, SD; 1.01, 95 % CI; 13.88 to 14.51, P= 0.0004]. Conclusion: Consciousness is not determined by the activity of a focal area of the cerebral cortex. Perhaps, we get our consciousness from the activity of “Neuronal Network of Coordination”.

Apraxic and Action-Intentional Disorders Associated With Vascular and Degenerative Dementing Diseases

2020 ◽  
pp. 146-184
Author(s):  
Kenneth M. Heilman
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Working Memory ◽  
Episodic Memory ◽  
Executive Functions ◽  
Vascular Dementia ◽  
Response Inhibition ◽  
Word Fluency ◽  
Letter Word ◽  
The Brain

“Actions speak louder than words.” Although clinician’s behavioral evaluations of dementia most often include assessing episodic memory, declarative memories (e.g., naming and calculating), and executive functions (working memory, letter–word fluency), one of the most important functions of the brain is programing actions, including “how” to move and “when” to move. Patients with Alzheimer’s disease, vascular dementia, and other forms of dementia often have impairments in the systems that mediate these how-apraxic and when-intentional behaviors. Although the presence of these apraxic and action-intentional disorders may help with diagnosis and help doctors gain a better understand these patients’ disability, these functions are rarely tested and are often not well understood. The goal of this chapter is to describe the signs of the various types of apraxic disorders (limb-kinetic, ideomotor, conceptual, ideational, and dissociation) and well as action-intentional disorders (akinesia-hypokinesia, impersistence, perseveration, and defective response inhibition), how to test for these disorders, and their pathophysiology.

scholarly journals Confidence-Related Decision Making

2010 ◽  
Vol 104 (1) ◽  
pp. 539-547 ◽  
Author(s):  
Andrea Insabato ◽  
Mario Pannunzi ◽  
Edmund T. Rolls ◽  
Gustavo Deco
Keyword(s):  
Decision Making ◽  
Cognitive Functioning ◽  
Neuronal Activity ◽  
Emergent Property ◽  
Neuronal Responses ◽  
Attractor Network ◽  
Firing Rates ◽  
Integrate And Fire ◽  
The Brain ◽  
High Firing

Neurons have been recorded that reflect in their firing rates the confidence in a decision. Here we show how this could arise as an emergent property in an integrate-and-fire attractor network model of decision making. The attractor network has populations of neurons that respond to each of the possible choices, each biased by the evidence for that choice, and there is competition between the attractor states until one population wins the competition and finishes with high firing that represents the decision. Noise resulting from the random spiking times of individual neurons makes the decision making probabilistic. We also show that a second attractor network can make decisions based on the confidence in the first decision. This system is supported by and accounts for neuronal responses recorded during decision making and makes predictions about the neuronal activity that will be found when a decision is made about whether to stay with a first decision or to abort the trial and start again. The research shows how monitoring can be performed in the brain and this has many implications for understanding cognitive functioning.

Normal Aging and the Brain

Physiology ◽  
1988 ◽  
Vol 3 (5) ◽  
pp. 197-200
Author(s):  
R Katzman
Keyword(s):  
Episodic Memory ◽  
Normal Aging ◽  
Intelligence Tests ◽  
Neural Basis ◽  
Very Old ◽  
Brain Processing ◽  
The Brain

During normal aging, cognition as measured by intelligence tests is remarkably preserved, although most of the very old show significant slowing of brain processing and mild loss of episodic memory. The neural basis for these changes is poorly understood.

Field Articulation, Sex, Spatial Visualization, Dependency, Practice, Laterality of the Brain and Birth Order

1974 ◽  
Vol 38 (3_suppl) ◽  
pp. 1223-1235 ◽  
Author(s):  
Julia A. Sherman
Keyword(s):  
College Students ◽  
Sex Differences ◽  
Birth Order ◽  
Left Hemisphere ◽  
Spatial Visualization ◽  
Spatial Function ◽  
Male College ◽  
The Right ◽  
The Brain ◽  
Rod And Frame

Among 25 female and 25 male college students, field-articulation measures correlated with spatial visualization (. −69 to .79) ( P ≤ .05) but not consistently with each other or measures of dependency. Practice significantly affected Rod-and-frame performance for both sexes ( p ≤ .01), but no sex differences were found on measures of field articulation or dependency. Males' mean for spatial visualization was higher ( p ≤ .05); males were more confident than females on RFT performance even though no more accurate ( p ≤ .05). Among Ss oldest of sibs, females were less field-articulated, males more. Males had higher RFT errors when the frame top was tilted to S's left; females had higher RFT errors when the frame was tilted to the right ( p ≤ .05), which is consistent with the hypothesis that for females more frequently than males control of spatial function is located in the left hemisphere of the brain.

Object, Space, and Object-Space Representations in the Primate Hippocampus

2005 ◽  
Vol 94 (1) ◽  
pp. 833-844 ◽  
Author(s):  
Edmund T. Rolls ◽  
Jianzhong Xiang ◽  
Leonardo Franco
Keyword(s):  
Episodic Memory ◽  
Spatial Information ◽  
Hippocampal Formation ◽  
Memory Task ◽  
Memory System ◽  
Important Advance ◽  
Object Space ◽  
Place Memory ◽  
Human Hippocampus ◽  
Spatial View

A fundamental question about the function of the primate including human hippocampus is whether object as well as allocentric spatial information is represented. Recordings were made from single hippocampal formation neurons while macaques performed an object-place memory task that required the monkeys to learn associations between objects and where they were shown in a room. Some neurons (10%) responded differently to different objects independently of location; other neurons (13%) responded to the spatial view independently of which object was present at the location; and some neurons (12%) responded to a combination of a particular object and the place where it was shown in the room. These results show that there are separate as well as combined representations of objects and their locations in space in the primate hippocampus. This is a property required in an episodic memory system, for which associations between objects and the places where they are seen are prototypical. The results thus provide an important advance by showing that a requirement for a human episodic memory system, separate and combined neuronal representations of objects and where they are seen “out there” in the environment, is present in the primate hippocampus.

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