Pavlovian fear conditioning is a behavioral paradigm in which organisms learn to predict aversive events. It is a form of learning in which an aversive stimulus is associated with a particular neutral context or neutral stimulus, resulting in the expression of fear responses to the originally neutral stimulus or context. This can be done by pairing the neutral stimulus with an aversive stimulus. Eventually, the neutral stimulus alone can elicit the state of fear. In the vocabulary of classical conditioning, the neutral stimulus or context is the "conditional stimulus" (CS), the aversive stimulus is the "unconditional stimulus" (US), and the fear is the "conditional response" (CR).
Immediate early genes (IEGs) are genes which are activated transiently and rapidly in response to a wide variety of cellular stimuli. They represent a standing response mechanism that is activated at the transcription level in the first round of response to stimuli, before any new proteins are synthesized. IEGs are distinct from "late response" genes, which can only be activated later, following the synthesis of early response gene products. Thus IEGs have been called the "gateway to the genomic response". The term can describe viral regulatory proteins that are synthesized following viral infection of a host cell, or cellular proteins that are made immediately following stimulation of a resting cell by extracellular signals.
Joseph E. LeDoux is an American neuroscientist whose research is primarily focused on survival circuits, including their impacts on emotions such as fear and anxiety. LeDoux is the Henry and Lucy Moses Professor of Science at New York University, and director of the Emotional Brain Institute, a collaboration between NYU and New York State with research sites at NYU and the Nathan Kline Institute for Psychiatric Research in Orangeburg, New York. He is also the lead singer and songwriter in the band The Amygdaloids.
In neuroscience, homeostatic plasticity refers to the capacity of neurons to regulate their own excitability relative to network activity. The term homeostatic plasticity derives from two opposing concepts: 'homeostatic' and plasticity, thus homeostatic plasticity means "staying the same through change". In the nervous system, neurons must be able to evolve with the development of their constantly changing environment while simultaneously staying the same amidst this change. This stability is important for neurons to maintain their activity and functionality to prevent neurons from carcinogenesis. At the same time, neurons need to have flexibility to adapt to changes and make connections to cope with the ever-changing environment of a developing nervous system.
Activity-dependent plasticity is a form of functional and structural neuroplasticity that arises from the use of cognitive functions and personal experience. Hence, it is the biological basis for learning and the formation of new memories. Activity-dependent plasticity is a form of neuroplasticity that arises from intrinsic or endogenous activity, as opposed to forms of neuroplasticity that arise from extrinsic or exogenous factors, such as electrical brain stimulation- or drug-induced neuroplasticity. The brain's ability to remodel itself forms the basis of the brain's capacity to retain memories, improve motor function, and enhance comprehension and speech amongst other things. It is this trait to retain and form memories that is associated with neural plasticity and therefore many of the functions individuals perform on a daily basis. This plasticity occurs as a result of changes in gene expression which are triggered by signaling cascades that are activated by various signaling molecules during increased neuronal activity.
Developmental plasticity is a general term referring to changes in neural connections during development as a result of environmental interactions as well as neural changes induced by learning. Much like neuroplasticity, or brain plasticity, developmental plasticity is specific to the change in neurons and synaptic connections as a consequence of developmental processes. A child creates most of these connections from birth to early childhood. There are three primary methods by which this may occur as the brain develops, but critical periods determine when lasting changes may form. Developmental plasticity may also be used in place of the term phenotypic plasticity when an organism in an embryonic or larval stage can alter its phenotype based on environmental factors. However, a main difference between the two is that phenotypic plasticity experienced during adulthood can be reversible, whereas traits that are considered developmentally plastic set foundations during early development that remain throughout the life of the organism.
Memory allocation is a process that determines which specific synapses and neurons in a neural network will store a given memory. Although multiple neurons can receive a stimulus, only a subset of the neurons will induce the necessary plasticity for memory encoding. The selection of this subset of neurons is termed neuronal allocation. Similarly, multiple synapses can be activated by a given set of inputs, but specific mechanisms determine which synapses actually go on to encode the memory, and this process is referred to as synaptic allocation. Memory allocation was first discovered in the lateral amygdala by Sheena Josselyn and colleagues in Alcino J. Silva's laboratory.
Many experiments have been done to find out how the brain interprets stimuli and how animals develop fear responses. The emotion, fear, has been hard-wired into almost every individual, due to its vital role in the survival of the individual. Researchers have found that fear is established unconsciously and that the amygdala is involved with fear conditioning.
Alcino J. Silva is a Portuguese-American neuroscientist who was the recipient of the 2008 Order of Prince Henry and elected as a fellow of the American Association for the Advancement of Science in 2013 for his contributions to the molecular cellular cognition of memory, a field he pioneered with the publication of two articles in Science in 1992.
Robert C. Malenka is a Nancy Friend Pritzker Professor in Psychiatry and Behavioral Sciences at Stanford University. He is also the director of the Nancy Friend Pritzker Laboratory in the Stanford Medical Center. He is a member of the National Academies of Sciences, Engineering, and Medicine, as well as the American Academy of Arts and Sciences. Malenka's laboratory research with the National Alzheimer's Foundation has informed researchers aiming to find a neuronal basis for Alzheimer's disease. Malenka's main career is focused on studying the mechanisms of synaptic plasticity and the effects of neural circuits on learning and memory.
Kay M. Tye is an American neuroscientist and professor and Wylie Vale Chair in the Salk Institute for Biological Sciences. Her research has focused on using optogenetics to identify connections in the brain that are involved in innate emotion, motivation and social behaviors.
Stephen Andrew Maren is an American behavioral neuroscientist investigating the brain mechanisms of emotional memory, particularly the role context plays in the behavioral expression of fear. He has discovered brain circuits regulating context-dependent memory, including mapping functional connections between the hippocampus, prefrontal cortex, and amygdala that are involved in the expression and extinction of learned fear responses.
Herwig Baier is a German-American neuroscientist and biologist. He is Director at the Max Planck Institute for Biological Intelligence and head of the department Genes – Circuits – Behavior. Herwig Baier's research aims to understand how animal brains convert sensory inputs into behavioral responses and how evolution has shaped neuronal circuits.
Dorothy P. "Dori" Schafer is an assistant professor in the department of neurobiology at University of Massachusetts Medical School. Her research focuses on the role of microglia in the development of synapses and brain circuits as well as the maintenance of synaptic plasticity.
Priya Rajasethupathy is a neuroscientist and assistant professor at the Rockefeller University, leading the Laboratory of Neural Dynamics and Cognition.
Rosemary C. Bagot is a Canadian neuroscientist who researches the mechanisms of altered brain function in depression. She is an assistant professor in behavioral neuroscience in the Department of Psychology at McGill University in Montreal, Canada. Her focus in behavioral neuroscience is on understanding the mechanisms of altered brain circuit function in depression. Employing a multidisciplinary approach, Bagot investigates why only some people who experience stress become depressed.
Nadine Gogolla is a Research Group Leader at the Max Planck Institute of Neurobiology in Martinsried, Germany as well as an Associate Faculty of the Graduate School for Systemic Neuroscience. Gogolla investigates the neural circuits underlying emotion to understand how the brain integrates external cues, feeling states, and emotions to make calculated behavioral decisions. Gogolla is known for her discovery using machine learning and two-photon microscopy to classify mouse facial expressions into emotion-like categories and correlate these facial expressions with neural activity in the insular cortex.
Moriel Zelikowsky is a neuroscientist at University of Utah School of Medicine. Her laboratory studies the brain circuits and neural mechanisms underlying stress, fear, and social behavior. Her previous work includes fear and the hippocampus, and the role of neuropeptide Tac2 in social isolation.
Ilana B. Witten is an American neuroscientist and professor of psychology and neuroscience at Princeton University. Witten studies the mesolimbic pathway, with a focus on the striatal neural circuit mechanisms driving reward learning and decision making.
Jessica Cardin is an American neuroscientist who is an associate professor of neuroscience at Yale University School of Medicine. Cardin's lab studies local circuits within the primary visual cortex to understand how cellular and synaptic interactions flexibly adapt to different behavioral states and contexts to give rise to visual perceptions and drive motivated behaviors. Cardin's lab applies their knowledge of adaptive cortical circuit regulation to probe how circuit dysfunction manifests in disease models.
