What is FDG in a PET?
Fluorodeoxyglucose or FDG is a PET tracer that measures the metabolic function of brain cells. FDG is uniquely sensitive and specific for differentiating Alzheimer’s disease from other forms of dementia, such as Frontotemporal degeneration. Recently, researchers have developed (and the FDA has approved) PET tracers that bind specifically ...
What is a Datscan?
DaTscan (I-123 ioflupane) is a nuclear imaging agent indicated for visualization of dopamine transporter distribution within the striatum (the brain region associated with Parkinsonism). Patients presenting with Parkinsons-like symptoms can be difficult to diagnosis. In the earliest stages or in patients with multiple comorbidities, there is often diagnostic uncertainty as clinical symptoms may overlap between different conditions. Single photon emission tomography (SPECT) images utilizing DaTscan (FDA-approved) may be a useful adjunctive tool for clarifying the diagnosis of essential tremor as compared to Parkinson’s disease. Other Parkinsonian syndromes will generate abnormal DaTscan images including multi-system atrophy, progressive supranuclear palsy, and diffuse Lewy body disease.
What is the Hattiesburg Clinic?
Hattiesburg Clinic Memory Center offers multiple imaging services to aid in the identification of various forms of dementia.
What is the Memory Center in Mississippi?
The Memory Center provides patients in south Mississippi with access to leading-edge clinical trials and care for those suffering with Alzheimer’s disease, dementia and other cognitive impairment disorders. By partnering with both academia and industry, the Memory Center is able to integrate research studies into the flow of clinical neurology practice.
What is PET in dementia?
PET enables evaluation of localized brain function and also allows for measurement (quantification) of the activity in specific brain regions. Although useful in a variety of illnesses, PET is particularly advantageous in the evaluation of dementia.
Is PET scan safe?
As a nuclear imaging technique, PET scanning involves the use of radioactive tracers. These tracers or “medications” are generally very safe and expose patients to minimal amounts of radioactivity (similar to a cardiac stress test). Fluorodeoxyglucose or FDG is a PET tracer that measures the metabolic function of brain cells. FDG is uniquely sensitive and specific for differentiating Alzheimer’s disease from other forms of dementia, such as Frontotemporal degeneration.
Does Hattiesburg Clinic use nuclear imaging?
Via participation in clinical research, as well as clinical experience with a large neurological patient population, Hattiesburg Clinic has developed significant experience utilizing these nuclear imaging techniques. Improved technical skills, imaging quality, and equipment upgrades have produced a nuclear neurology service that allows for unprecedented access to these leading-edge technologies within our region.
What is the purpose of artificial engram cell reactivation?
Therefore, artificial engram cell reactivation serves as a sufficient retrieval cue to “reawaken” a dormant engram to induce memory expression , similar to Semon’s original definition of ecphory [“the influences which awaken the mnemic trace or engram out of its latent state into one of manifested activity” (5, p. 12)].
What is an engram cell ensemble?
An “engram cell ensemble” refers to the collection of engram cells localized within a brain region. Engram cell ensembles in each brain region are connected, forming an “engram complex,” which is the entire brainwide engram supporting a memory that is stored in sets of engram cell ensembles in different brain regions connected via an engram cell pathway.
How do gain-of-function studies induce memory retrieval?
Gain-of-function studies attempt to induce memory retrieval in the absence of natural retrieval cues by artificially reactivating engram cells. Tonegawa and colleagues (69) provided the first gain-of-function evidence for the existence of an engram. Hippocampal dentate gyrus (DG) neurons active during contextual fear conditioning (in which a context was paired with a footshock) were tagged (41) to express the excitatory opsin channelrhodopsin 2 (ChR2) (70). When tested in a nontraining context, mice did not freeze. However, photo-stimulation of tagged engram cells was sufficient to induce freezing, the learning-specific conditioned response (44), even though mice had never been shocked in this nontraining context (Fig. 2). Importantly, light-induced freezing was not due to activation of pre-wired learning-independent neural circuits or a simple reflex response, because similar photo-stimulation of tagged DG neurons failed to induce freezing if downstream CA1 neurons were silenced during training (thereby preventing learning) (71).
What is the engram of memory?
The idea that memory is stored as enduring changes in the brain dates back at least to the time of Plato and Aristotle (circa 350 BCE), but its scientific articulation emerged in the 20th century when Richard Semon introduced the term “engram” to describe the neural substrate for storing and recalling memories. Essentially, Semon proposed that an experience activates a population of neurons that undergo persistent chemical and/or physical changes to become an engram. Subsequent reactivation of the engram by cues available at the time of the experience induces memory retrieval. After Karl Lashley failed to find the engram in a rat brain, studies attempting to localize an engram were largely abandoned. Spurred by Donald O. Hebb’s theory that augmented synaptic strength and neuronal connectivity are critical for memory formation, many researchers showed that enhanced synaptic strength was correlated with memory. Nonetheless, the causal relationship between these enduring changes in synaptic connectivity with a specific, behaviorally identifiable memory at the level of the cell ensemble (an engram) awaited further advances in experimental technologies.
How does optogenetic stimulation help with memory retrieval?
That is, artificial stimulation replaced the natural conditioned stimulus to induce memory retrieval. Optogenetic stimulation of engram cells has also been used to artificially retrieve a previously experienced sensory stimulus during the formation of a new memory. For instance, DG neurons active during exploration of a new context (context A) were photostimulated when mice later received footshocks in a different context (context B). During a memory test, mice replaced in context A froze, even though they had never been shocked in this context. That is, mice retrieved an artificial memory. Mice also froze in context B (showing natural memory retrieval), but not in a third distinct context (context C), indicating freezing was a context-specific, and not a generalized, response (46). Both memories produced by “natural” and “artificial” means could only be retrieved by their respective conditioned stimuli, indicating both memories retained their identities. Similar to a compound conditioned stimulus in which both a tone and light predict footshock, the strength of the natural and artificial memories were roughly 50% of a single “normally induced” memory, suggesting cue competition between the natural and artificial conditioned stimuli [as originally described by (82)]. Therefore, when a biologically important event (e.g., footshock) occurs while an animal is retrieving a previously formed but perhaps unrelated memory, the two stimuli can be associated to form a new but false episodic memory. An analogous mechanism may underlie human false memories, except that in humans, the previously acquired memory would be retrieved by natural processes (83).
What is loss of function in memory?
Loss-of-function studies attempt to “capture” engram cells and specifically disrupt their function before a memory test. Josselyn and colleagues (58) performed the first loss-of-function memory study at the level of a cell ensemble. An allocation strategy was used to capture putative engram cells in the amygdala lateral nucleus (LA) supporting an auditory fear conditioned memory in mice. That is, a small, random population of LA neurons was biased for inclusion (or allocation) into a putative engram using a neurotropic virus expressing CREB (Ca++/cyclic AMP–responsive element-binding protein). CREB is a transcription factor that increases both neuronal excitability (59–64) and dendritic spine density (60, 65). Therefore, neurons infected with this CREB vector were hypothesized to be biased for inclusion into an engram. A virus expressing both CREB (to allocate neurons) and an inducible construct that produces cell-autonomous ablation was used to specifically kill allocated neurons after training (58). Ablating CREB-overexpressing neurons disrupted freezing to subsequent tone presentation, as if the memory was erased (Fig. 1). Importantly, mice were capable of learning a new fear conditioning task (showing overall LA function was not compromised), and ablating a similar number of non–CREB-overexpressing cells (nonengram cells) did not disrupt memory (showing specificity of the memory disruption at the cellular level).
How to evaluate engrams?
To evaluate the existence of engrams, we adapt the criteria and experimental strategies discussed by Morris and colleagues (21 , 22) in their landmark papers evaluating the importance of synaptic plasticity in memory. Specifically, we discuss evidence from four types of studies. First, observational studies supporting the existence of engrams in the rodent brain should show that the same (or overlapping) cell populations are activated both by an experience and by retrieval of that experience and that, furthermore, learning should induce long-lasting cellular and/or synaptic modifications in these cells. Second, loss-of-function studies should show that impairing engram cell function after an experience impairs subsequent memory retrieval. Third, gain-of-function studies should show that artificially activating engram cells induces memory retrieval, in the absence of any natural sensory retrieval cues. Fourth, mimicry studies should artificially introduce an engram of an experience that never happened into the brain and show that rodents use the information of an artificial engram to guide behavior.
How does NBS affect memory?
The effects depend on the stimulation parameters. TMS and tDCS can be used to interfere with ongoing brain activity (“virtual lesion”) and thus help to characterize brain–behavior relations, give information about the chronometry of cognitive processes, and reveal causal relationships. Particularly in real-time combination with electroencephalography (EEG) or functional magnetic resonance imaging (fMRI), TMS and tDCS are valuable tools for neuropsychological research. They offer the combination of interference methods (TMS, tDCS) with techniques to record ongoing brain activity with high temporal (EEG) and spatial (MRI) resolution. This can: (1) shed unique insights into physiological and behavioral interactions, and (2) test, refine, and improve cognitive models; and (3) might ultimately lead to better neurorehabilitative methods.
What is motor memory?
Motor learning and the formation of motor memories can be defined as an improvement of motor skills through practice, which are associated with long-lasting neuronal changes. They rely primarily on the primary motor cortex, premotor and supplementary motor cortices, cerebellum, thalamus, and striatal areas (Karni et al., 1998; Muellbacher et al., 2002; Seidler et al., 2002; Ungerleider et al., 2002). As learned from patients with apraxia, the parietal cortex is furthermore implicated in accessing long-term stored motor skills and contributes to visuospatial processing during motor learning (Halsband and Lange, 2006). Frontoparietal networks may become important after learning has been established, and play key roles in consolidation and storage of skill (Wheaton and Hallett, 2007).
What is the role of parietal regions in memory?
There are debates over the implication of attention functions to memory and specifically, for example, of the role of parietal regions to retrieval of episodic memory. For instance, the Attention to Memory (AtoM) model postulates that the dorsal parietal cortex mediates top-down attention processes guided by retrieval goals (orienting), while ventral parietal cortex mediates automatic bottom-up attention processes captured by retrieved memory output (detection) (Ciaramelli et al., 2008; Cabeza et al., 2011). Cabeza and colleagues (2011)have proposed that parietal regions control attention in a similar way to perception processes. While orienting-related activity for memory and perception are thought to overlap in dorsoparietal cortex (DPC), detection-related activity is believed to overlap in ventroparietal cortex (VPC). Furthermore, both DPC and VPC show strong connectivity with medial–temporal lobe (MTL) during a memory task, which can, however, shift to strong connectivity with visual cortex during a perception task. Accordingly, the DPC appears to be collaborating with the prefrontal cortex (PFC) to induce top-down attention to salient retrieval paths, while the VPC seems to be involved in the activation of episodic features in alliance with the MTL. Thus, current models of memory processes integrate dynamic concepts of distributed network interactions and plasticity. These and other conclusions are derived from brain imaging studies, which, although extremely valuable, cannot offer insights into causality (Silvanto and Pascual-Leone, 2012). Here again, NBS offers the promise of a transformative approach.
What is the difference between explicit and implicit memory?
Historically, the distinction between explicit and implicit memory has been associated with declarative and nondeclarative memory. It is often argued that declarative memory (semantic and episodic memory) corresponds to explicit memories that are conscious and verbally transmittable. On the other hand, nondeclarative memory is thought to represent an implicit and nonverbal type of memory that is acquired subconsciously. Although most declarative memory contents seem to be acquired explicitly, and most nondeclarative memory contents appear to be acquired implicitly, this dichotomy is an oversimplification and ultimately not accurate. For example, declarative memories can be acquired subconsciously (e.g., memories of an emotionally intense event or subliminal priming effects), and nondeclarative memories can be acquired with conscious engagement (e.g., learning of motor movements playing sports or a musical instrument).
What are the two types of memory?
A key advance in the study of the neurobiological substrates of memory was Squire’s (1987, 2004) distinction between declarative and nondeclarative memory functions related to their differential reliance on distinct neural structures (Cohen and Squire, 1980). Declarative memory incorporates semantic and episodic memory, and refers to everyday memory functions, which are typically impaired in amnesic patients. Declarative memory is thought to rely primarily on medial temporal lobe structures, including the hippocampus. Nondeclarative memory includes various subcomponents, of which procedural memory or formation of motor memories is the most prominent. Nondeclarative memory is thought to depend mostly on striatum, cerebellum, and cortical association areas (Cohen and Squire, 1980). However, procedural memory also includes associative learning forms, such as classical and operant conditioning, and nonassociative learning forms such as priming, habituation, and learning of perceptual and cognitive routines. Notably, motor learning has been regarded as a less cognitive form of memory functions, and most research makes a clear distinction between motor and nonmotor memory functions. Thus, it seems clear that declarative and nondeclarative memory processes are interactive and partly overlapping domains.
How is learning and memory investigated?
In the literature we find studies that use brain imaging during memory tasks, analyze the number of remembered items correlated with EEG activity, look at the influence of state changes as captured by various brain imaging and neurophysiological measures, or “borrow patients’ illnesses” to investigate the impact of serendipitous lesions. The application of all these methods has led to valuable information about the neural mechanisms of memory. However, cause–effect relationships are difficult to establish. NBS is uniquely suited to provide this (Silvanto and Pascual-Leone, 2012).
What is learning and memory?
Learning and memory are cognitive functions that encompass a variety of subcomponents. These components can be structured in different ways. For example, we can focus on their temporal dimension, or differentiate various forms of memory by virtue of their content or mechanisms of acquisition (Fig. 55.1). It seems clear that the cognitive structure of learning and memory is complex, and that, given the many interactions and overlaps between key subcomponents, neither neuropsychological nor neurobiological models can give us a fully satisfying taxonomy.
How to know if your visual memory is poor?
How To Know When Your Visual Memory Is Poor. Someone who has a problem with visual memory, particularly a child, may display the following signs: Reading comprehension may be poor, and they may have to sound out every word. Spelling may be poor. Math skills may be poor, and using a calculator may be challenging.
Why is visual memory important?
Long-term memories can also be created because of repeated sightings. For example, when you repeatedly drive to a location, you will eventually learn the route without using GPS or any other aid. Visual memory is important in the world of learning; as much as 80 percent of what we learn is visual.
What does it mean when you look up and to the left?
If someone is trying to recall a long-term visual memory , they will tend to look up and to the left. If they look up and to the right, they are likely to be trying to recall a short-term visual memory. However, not all people have these “tells.” Some reverse this pattern, and others don’t have it at all.
What is the most basic way to learn?
Recalling something we've seen is one of the most basic ways we learn. If you have a hard time recalling what you’ve seen, it will be more difficult to learn. There are two types of visual memory: Short-term visual memory. This is when we can recall something we've seen not too long ago.
How to improve written instruction?
Use Both Audio and Visual Memory. To enhance written instructions, for example on a homework assignment, give your child verbal instructions as well. This reinforcement helps not only with auditory learning but also with connecting the dots between auditory and visual memory.
How to help someone with visual memory?
To help someone with their visual memory, you can ask questions about their day. Ask them what they did for lunch, what they did after school, and so on. They will need to rely on visual memory to find the answers.
What is visual memory?
However, visual memory, for the most part, means that you are looking at the objects in your environment rather than the space. Visual memory is also related to something called visual form constancy.
What is Forensic Imaging?
Forensic imaging, in a nutshell, is the act of gathering data in a court accepted fashion from digital media to a Veracrypted encrypted output device where possible. That data may come from a live system, a dead PC, DVD, iMac, USB disk, X-Box or remote mailbox. Those are just a few examples.
What is a Logical Forensic Image?
A logical forensic image or skeleton image is a particular copy of certain files from a source. Many programs can produce logical images: Stefan Fleischmann’s excellent X-Way’s Imager, the superb and free FTK Imager or new on the scene Magnet’s Acquire software can be used to do this in a Windows environment.
What is Redline's use of memoryze?
Redline uses Memoryze in the background to "audit" memory — essentially turning all that seemingly chaotic and unstructured data into the processes, drivers, and memory sections understood by the operating system.
What happens if USB is not available?
If USB is not an option in your environment, the same process can be conducted using other media, such as a CD-R. In this situation, output could be redirected to a network share or equivalent.
Is Mandiant Memoryze a revolutionary change?
I credit the free Mandiant Memoryze tool with popularizing the idea of performing live memory analysis, and I believe it is a revolutionary change. The idea itself could be as controversial as creating a memory image was just a few years ago. Do you remember the naysayers questioning how our forensic analysis could possibly be valid if we were to run our imaging applications on the live system? Shouldn't we still be pulling the plug? What would they say if we now told them we were going to play "Find the Hacker" on that same live system? Luckily it turns out that the system impact of doing a live analysis versus (or in addition to) taking a memory image is minimal. And the benefits are great:
Can Redline create audits?
Redline can create these audits from an existing memory image or it can kick off a live analysis on the current system (see Figure 1). While the latter feature can be useful, it does require installation of the Redline and .NET binaries, which may not be feasible or desired. Figure 1: Analyze this Computer.
Who is Chad Tilbury?
Chad Tilbury, GCFA, has spent over twelve years conducting computer crime investigations ranging from hacking to espionage to multi-million dollar fraud cases. He teaches FOR408 Windows Forensics and FOR508 Advanced Computer Forensic Analysis and Incident Response for the SANS Institute. Find him on Twitter @chadtilbury or at http://ForensicMethods.com.
What is Memory Forensics?
Memory forensics is a vital form of cyber investigation that allows an investigator to identify unauthorized and anomalous activity on a target computer or server. This is usually achieved by running special software that captures the current state of the system’s memory as a snapshot file, also known as a memory dump. This file can then be taken offsite and searched by the investigator.
What is a Belkasoft RAM capturer?
Belkasoft RAM Capturer: This is another forensic tool that allows for the volatile section of system memory to be captured to a file. First responders will find that the functionality and wide range of tools available in this software package will allow for their investigations to start off as quickly as possible.
Why is memory forensics important?
Memory forensics is a crucial skill for first responders and investigators alike, as it allows for the quick and complete capturing of live system data for later scrutiny. And while this is a very important skill to learn, it is just one of the tools that you will be taught when enrolling in one of the many forensic training courses that are offered in the CCFE.
What is forensic investigator?
Forensic investigators are highly skilled and can identify activity on a system that should not be present, allowing them to prove that a system has been compromised. It allows them to identify rootkits and malware, to find unusual processes, and reveal covert communication, which can shed light on what is happening currently in a target system.
Why is snapshot important?
This is useful because of the way in which processes, files and programs are run in memory, and once a snapshot has been captured, many important facts can be ascertained by the investigator, such as:
What is process hacker?
Process Hacker: This is an open source process monitoring application that is very useful to run while the target machine is in use. It will give the investigator a better understanding of what is currently affecting the system before the memory snapshot is taken, and can go a long way to help uncover any malicious processes, or even help to identify what processes have been terminated within a set period of time.
What is a time stomp?
This is known as time stomping, and can seriously inhibit an investigator’s ability to discover when the infection first occurred. By capturing the memory dump, investigators can compare the process time stamps to the system file timestamps to establish when the system was first compromised.
