Exam 2 Flashcards
Cognitive Neuroscience
Study of the underlying mechanisms of cognition
Overlaps with cognitive psychology, neurophysiology, psychiatry, neurobiology, neurology, etc.
Anne Greene and Dr. Willis
Accused of murdering her baby, sentenced to death. Hung for 30 minutes and her body was promised to two doctors for autopsy. Within 12 hours she was speaking. Walk talk eat after a week.
Dr. Wilis that was supposed to do the autopsy became famous after this event and began teaching at Oxford, later coined term “neurology”. Performed autopsies on those that he treated and connected individual differences with neuroanatomy
How is neurology studied today
Functional neuroimaging
Electrophysiologic expermients
Cognitive genetics
Traditional clinical studies
Building the brain
genetics and experience help to inform some of the process
Synapses are crucial as they can reversibly connect sets of neurons (neural networks/assemblies)
Networks are composed of neurons that fire together. Building blocks of cognitive function
Neural networks
All cognitive functions are attributed to functioning of neural networks
Synapses are able to wire together large numbers of widespread neurons
Nature with nurture
Genetics:
lays neuronal groundwork
apoptosis
Variability in genomic plan
Experience:
refinement of neural system
Stimuli will alter synapses
“wiring by firing”
Neuronal change over time
Begin with genetics and after birth enter refinement until death
Neural development overview
Embryonic ectoderm gives rise to the nervous system
CNS forms the neural tube
PNS forms the neural crest
Prior to birth neurogenesis is mostly complete
Differentiation of neurons and neuroglial cells begins following development of the neural tube into a rudimentary brain and spinal cord
Neuron differentiation overview
Neurons differentiate first and the neuroglial cells
BEFORE THEY DIFFERENTIATE neurons and glia must travel to their final locations
Reaching their terminal location is necessary for their survival as they must form PARTICULAR synaptic neurons
IF NOT they undergo apoptosis
Migration of neurons
Follow signal transduction molecules and cell surface and extracellular adhesion molecules
Some are chemoattractants and other are chemorepellants
Molecules also guide growing axons
construction of synapses
Appropriate synaptic connections must be made following neurogenesis and migration
Signaling molecules allow the axonal growth cone to correctly identify the path to take
Growth factors assist with the growth of the axon, formation of the synapse and altering the number of connections
Failure to form aan appropriate synapse results in the loss of the axon (trophic nature of the synapse involves growth factors including Protein Nerve Growth Factor
Hebbian Assemblies
Conversion of the growth cone to a presynaptic specialization circuitry can be established
Forming new and modifying existing networks follows the same principles and utilizes the same mechanisms as Hebb’s synaptic plasticity
Long term Potentiation and Long Term Depression
LTP
Requires simultaneous presynaptic and postsynaptic neuronal firing (glutamate and NMDA receptors)
Large amount of Ca ions enter the postsynaptic neuron
Induce LTP by initiating STP and activating protein kinases
NMDA receptors
BOTH ligand gated and charge gated
LTD
Requires asynchronous firing of pre and post-synaptic firing
Requires glutamate and its NMDA receptor
Small influx of Ca ions, initiation of STP, activation of protein phosphatases
LTP vs. LTD
Both require activation of NMDA receptors and entry of Ca into the post-synaptic cell
Main difference is the amount in the post-synaptic neuron
Small influxes = depression
Large influxes = potentiation
LTP relies on the activity of protein kinases
LTD relies on the activity of protein phosphorylases
Often activate and inactivate the same complexes
Types of neural connections
Serial - Arrangement of neurons within an assembly that is linear; Vulnerable to damage
Distributed - Arrangement of neurons within assmebly that contain multiple interconnections. More resilient to damage
Excitatory Connections
Feedforward excitatory connection: low level –> High level
Feedback excitatory connection: Stimulation of postsynaptic neuron (high level –> low level)
Lateral excitatory connection: Stimulates other presynaptic
Inhibitory connections
Feedforward inhibitory - signals one neuron to inhibit another neuron.
Feedback inhibitory - stimulate another neuron that stimulates a neuron that inhibits the original neuron
Lateral inhibitory - similar to other lateral
Produces a signal that causes signaled neuron to release inhibitory signal
Disinhibition
Inhibiton of inhibition leads to excitation
For example: the globus palladus is typically an inhibitor. The caudate nucleus inhibits the globus palladus and leads to an over all stimulatory effect on thalamus)
Divergence stream
One stream to many others
Convergence stream
Severasl neurons to one
convergence and divergence may occur at the same neuron
Lots of convergence of rods, little convergence in cones
Circuit types
Hierarchecal circuit
Local circuit
Hierarchecal circuit
Each level is regulated by local circuits and three types of processing occur in circuits
Serial processing: info flows from one area to another in the sequence
Parallel processing: Info flows side by side
Reciprocal processing: info flows back and forth
Local circuit
Circuits found within heirarchechal circuits
Alter processing at each level. can also determine information passed to the next stage
Local circuits include: Feedforward and feebackward connections. Excitatory and inhibitory connections
Number and complexity of synaptic neurons
Cortex contains 90 billion neurons
75% pyramidal neurons
25% stellate neurons
w/ divergence: 18,000 synapses from a single pyramidal neuron; 10,000 per stellate neurons
Connectomics
mapping all of the interconnecting circuits of the nervous system
“brainbow” genetic marker that color codes neurons
Cells of the nervous system
Neurons Neuroglial cells (non-neuronal cells that perform various functions. Outnumber neurons by a factor of 10)
CNS Neuroglia
Oligodendrocytes - During development these cells send out processes to contact nearby neurons and form myelin sheaths
Astrocytes - Many functions (other card)
Microglial cells - Small somas and numerous processes. Mediate immune response in CNS. Able to divide. Phagosytose degenerating cells that are undergoing apoptosis. During development they aid in fiber tract development, gliogenesis, and angiogenesis by secreting GF. Antigen presentation. Become reactive and phagocytic in pathogen in the CNS of an adult.
Astrocytes
Starlike cells with multiple processes.
Produce ECM proteins and chemicals that guide neurons during migration. Secrete growth factors that regulate morphology, differentiation, and proliferation of neurons (survival).
Maintain tight junction of endothelial cells to promote blood-brain barrier. NT removal from synaptic cleft via uptake.
Sequester metals and neurotoxic material away. (detoxify)
Generates intracellular Ca waves for intracellular and potentiatally intercellular signaling
May increase the numbers of astrocytes and recruitment in response to injury, disease and can form glial scars
Schwann cells
Exist in PNS
Generate myelin in the PNS. One Schwann cell will only produce one myelin sheath segment.
Secrete extracellular matrix components to create a sleeve
Respond to neural injury by secreting GF, removing debris from site, provide structural support and guidance to regenerating axon.
Neural triad
Neurons
Glia
Vasculature
Cerebral Vasculature
Contributes to neurogenesis
Transports O2 and nutrients into the brain and removes metabolic waste and CO2
Endothelial cells interact with astrocytes to form the BBBarrier
Tripartite synapse
when an astrocyte process contacts both the presynaptic and postsynaptic portion of two synapsing neurons
Ca is released from storage in the astrocyte in response to metabotropic receptor activity (initiates an STP that releases Ca)
Changes in intracellular levels of Ca results in the release of glutamate, ATP, D-serine (gliotransmitters)
Not an all or none principle. There may be only a portion of the astrocyte activated
Maintenance of Synapse Homeostasis
Astrocytes influence synapse function by regulating homeostasis of the interstitial fluid within a synapse
via aquaporins and ion transporters that allow for pH change and ion level balances
Gliotransmitters at the tripartite synapse
ATP - Glia to glia - Metabotropic receptor - decreases glial cell Ca levels
Glutamate - Neurons and glia - N: ionotropic receptors (AMPAR’s and NMDAR’s); Astro: Metabotropic receptors - Enhances NT release, enhances EPSPS, can increase or decrease Ca levels
D-serine - Postsynaptic neuron - ionotropic receptor (NMDAR) - enhance EPSPS
Functional Neuroimaging
Can measure neural activity directly by either electrical or magnetic changes produced in response to neural activation or
indirectly by measuring cerebral blood flow, blood oxygen levels, or oxygen or glucose consumption
Measuring electrical and magnetic signals
EEG: electrical potentials of a large population are measured by electrodes. Overall brain activity. Sleep and wake have been measured. Can compare to other electroencephalogram to detect abnormality. Good temporal quality but poor spatial quality
MEG: measures neural activity by capturing magnetic fields produced by active neurons. Similar temporal resolution but better spatial spatial resolution
Metabolic signals
indirect measurement of neural activity
Positron Emission Tomography: measures local changes in cerebral blood flow. Radioactive tracer injected into the blood stream. First administered at rest and then at experiment. high levels of gamma levels indicate high levels of blood flow and increased function
fMRI: Relies on the magnetic properties of hemoglobin. Measures the ratio of oxygenated to deoxygenated HG in the blood (Blood oxygen level-dependent effect). With increased activity the BOLD will increase. Better than PET
Photoacoustic Imaging: Used for static imaging and Functional imaging. Pulsed laser is shot into tissue to create pressure waves. Ultrasound transducer outside of the tissue detects waves and generates images. Used to measure BO saturation, blood flow, or temperature. Used with a tracer or probe. High spatial resolution and lower cost than PET
Cognitive network characteristics
Appear early during embryonic development
Support all cognitive function
Constantly modulate neural activity and are referred to as “brain state modulatory controls”. Regulate widespread information flow throughout the brain.
Organized in a hierarchy
Exhibit functional stability in the face of local network damage
Are created and altered by synaptic plasticity processes
Consist of many long reaching axonal branches
Categorized by NT utilized
Biogenic amine transmitter
Regulate various brain functions and are implicated in a variety of biological roles ranging from homeostatic maintenance to cognitive processes
Defects in networks using these NT is usually indicative of phsyciatric disorders
Dopamine, NE/E, histamine, serotonin
acetylcholine important in PNS and CNS for many functions
General features of Single-source divergent networks
Utilize a unique NT (all small molecule NT and Ca release dependent)
Source of neurons that release a single NT is contained in a nuclei
Location of nuclei: Brainstem, hypothalamus, and basal forebrain
Network neurons have unmyelinated neurons that are highly arborized.
All 5 networks are interconnected and work together to control overall brainstate.
Neural network local circuits
Connect the 5 single-source systems
Contain excitatory and inhibitory synapses
Serial, Parallel and reciprocal processing connections
Overall brain state control
Accomplished by the 5 single source divergent networks
interact with each other and also send processes to other regions of the brain such as the thalamus and cortical regions
consciousness, sleep and wakefulness, attention, emotions, learning and memory processes, and the monitoring of overall physiologic state of the body
5 systems affects on spinal cord, thalamus, cortex
Affects all regions of the spinal cord
Has an indirect effect on the thalamus via thalamic reticular nuclei, intralaminar nuclei
Affects all regions of the cortex
Non-directed synapses
unmyelinated axons of the neurons of the 5 systems release NT through these
NT molecules are released in response to intracellular Ca from varicosities of the axons.
NT molecules can then diffuse freely in many directions
Large number of cells are affected
Long duration of modulatory effects
Ascending reticular activating system
Includes several circuites which originiate from the brainstem and ascend through the intralaminar thalamic nuclei and thalamic reticular nucleus to the cerebral cortex
All five of the single source divergent networks communicate via the axonal projections in of the thalamic ARAS
Produces state of conciousness
Thalamic ARAS Functional Nuclear Relay Regions
Intralaminar thalamic nuclei (ILn) and the thalamic reticular nucleus (TRn)
Norepinepherine/Noradrenaline (NE/NA) System
Norepinephrine is created in the locus coeruleus
Actiosn can be either inhibitory and excitatory
Lc sends projections to the cerebrum, hippocampus, cerebellum, and hypothalamus. Also limbic structures like the amygdala.
Norepinepherine/Noradrenaline (NE/NA) System Function
Attention and arousal Fight or flight Negative emotion processing Regulaton of deep sleep Support learning and memory Aid in cognitive performance
Histamine system
Found in neurons in the hypothalamus
Send out axonal projections to regions of the spinal cord
Tubermamillary nucleus is th esole source in the CNS
Only excitatory
Targets include:
Brainstem, spinal cord, hippocampus, thalamus, cerebellum, cerebrum
Functions of the histamine system
Mediation of arousal and attentionModulation of body energy stores
Control of circadian rhythms
Support memory and learning
Serotonin system
Produced mainly in several groups of neurons known collectively as the Raphe nuclei. found in region from pons to the midbrain
Inhibitory/excitatory
Cerebellum, brainstem, spinal cord, thalamus, hypothalamus, cerebrum
Functions of serotonin system
Mediation of attention and arousal Suppresion of behavior Modulation of negative emotions Support learning and memory Control of deep sleep
Acetylcholine system
eight distinct nuclei (Nucleus basalis of meynert and pentopeduncular nucleus)
The NB is located below the anterior part of the thalamus and lenticular nucleus within the anterior perforated substance. The PPN is located in the midbrain adjacent to the substantia nigra
Excitatory only actionat NMJ but both in the brain
thalamus, hypothalamus, hippocampus, cerebrum
Functions of acetylcholine system
Mediate attention and arousal
Support learning and memory
Control REM sleep
Dopamine system
Specifically in nuclei of the ventral tegmental area (VTA) and of the substantia nigra (SN). MIDBRAIN
Target neurons of the nucleus accumbens of the basal forebrain
Functions of dopamine system include
positive reward network and motivation
positive emotion and mood
Supports learning and memory
Mediates attention and arousal
Positive reward network
Dopamine plays a role in reward, reinforcement, and motivation
Increased activation of dopamine system leads to the production of positive feelings. The more often these pathways are stimulated the greater the drive for whatever pathway caused the surge becomes (caution)
Dopamine activation and drugs
Cocaine and amphetamine stimulate system by blocking reuptake and transport of dopamine away from synaptic cleft. This results in a net increase in the dopamine in the cleft and activates dopaminergic system
methamphetamine and amphetamine also stimulate Ca dependent release of DA into the synaptic cleft
Opium and heroin achieve their effects via disinhibition: they inhibit GABA-ergic inhibitory interneurons and increase firing of the DA neurons in the VTA. THC is also able to inhibit interneurons that inhibit VTA neurons
Nicotine binds a glutamate receptor on glutamergic neurons that excite VTA neurons. Glutamate then binds to receptors on VTA neurons and releases dopamine
Sleep-Wake cycle
Awake stage: Individual is conscious and all 5 networks are active
Non-REM sleep
REM Sleep
Non-REM sleep
Stages 1-4 are non-REM sleepTriggered by the release of adonsine from astrocytes
Activity of NA neurons in the locus coerulous and the 5-HT neurons of the raphe nuclei
Stages 1-2: light sleep
Stage 3: moderate deep sleep
Stage 4: Deepest level of sleep (Slow-wave sleep)
REM Sleep
Follows the 4 stages of REM sleep
Vivid hallucinations
Activation of Cholinergic neurons in the pons initiates effects of REM sleep
Increased activity of the GABergic neurons in the reticular formation (pons) send projections to inhibitory neurons that synapse on LMN and produce the physical paralysis of sleep
EEG recordings taken during REM sleep are similar to those of the awake state
An individual will cycle through 4 periods of REM sleep per sleep wake cycle
which of the 5 systems are active with wakefulness states
Awake: ALL 5
Non-REM sleep: Norepinephrine, serotonin
REM sleep: Acetylcholine
Importance of REM sleep
During development REM sleep occupies a greaterpercentage of sleep-wake cycle than in adults
REM rebound: REM hours will catch up with lost time after sleep deprivation
With REM deprivation performance on cognitive tasks were decreased
Important for memory consildation:
Greater % of REM sleep with periods of intense mental activity
REM brain wave patterns are repeated for tasks learned before REM sleep
Memory deficits follow REM deprivation
Importance of Non-REM sleep
Conservation of energy and restoration of the mind
No effect on body (with deprivation can still exercise but there are marked cognitive deficits)
Sleep induction theory
Release of NT uses up stores of glycogen and with energy source depletion glial cells release adenosine
Receptors in the cerebral cortex, thalamus, and brainstem bind adenosine that promotes the induction of Non-REM sleep
Periods of non-REM sleep replenish glycogen stores of the glial cells
Sleep and removal of waste in brain
As one sleeps the cells of the brain contract allowing for CSF to flow through and depost metabolic waste into the vasculature
Disruption of waste removal is implicated in neurological disorders such as Alzheimer’s and formation of amyloid beta plaque’s
Glymphatic system
Form of lymphatic system used by CNS. Significantly enhanced during sleep and inhibited while awake
rapid fluid exchange between CSF and interstitial fluid facilitated by aquaporins found on the endfeet of astrocytes which completely surround the vasculature
Fluid moves into the brain parenchymaand towards the space surrounding large veins
Leaves the brain as it is drained into the central lymphatic system
Driving forces of glymphatic transport of CSF
Constant production of CSF pushes CSF to flow into the subarachnoid space
Respiration can aid the movement of CSF through the ventricular system
Smooth muscle surrounding the pial and penetrating arteries cause pulsation that can drive fluid movement
Positive emotions
Modulated through dopamine
Dopaminergic neurons of the Ventral tegmental area in the brainstem send projections to the basal forebrain (nucleus accumbens)
ACtivates nucleus accumbens and consequently activity of the amygdala is inhibited
VTA also sends projections to medial prefrontal cortex which aids in the processes of working memory with positive emotion. Anterior and posterior areas of the cingulate gyrus which is involved in attention. Insula which aids in the modulation of all emotions
Negative emotions
Processed through the NE and the serotonin systems
Serotinergic neurons of the raphe nuclei and the noradrenergic neurons of the locus coeruleus along with neurons within the periaqueductal region send excitatory neurons to the amygdala. Acivation of the amygdala suppresses the activity of the nucleus accumbens
The Lc, nR, and PAR activate the orbital prefrontal cortex for working memory with negative emotion, anterior cingulate gyrus which focuses attention, and the insula
Cortical column properties
Functional units of information processing in all cortical regions (sensory and motor input and cognitive function)
Contains 100 neurons
Typically contains 6 distinct histological layers
Neurons within a column respond to similar stimuli. Columns can be linked together to form larger groupings that reach across the cortex and subcortical area, particularly the thalamus
Cortical layers 1-3
Supragranular layers: upper three layers closest to the cortical surface
L1: molecular layer - synaptic field comprised of dendrite and axonal branches of other neurons
L2: external granular layer - pyramidal cells and interneurons
L3: external pyramidal layer - contains pyramidal cells
All of these layer send projections to layers of other cortical columns
Reciprocal connections with 1-3 layers. Nonreciprocal connections with 5-6
Cortical layer 4
Divides cortical column into supra/infragranular regions
Contains mostly stellate cells
Input from thalamus
Input to other layers within the same column
Cortical layer 5-6
Infragranular layers
Input from supragranular layers of adjacent columns
L5: large pyramidal cells, interneurons and Betz cells in the primary moto cortex
L6:Contains fusiform neurons, pyramidal cells, and interneurons
Does not send projections back to adjacent columns
Sends projections to thalamus, straitum, brainstem, and spinal cord
Cortical columns and the thalamus
Thalamus receives input from all regions of the brain
Works with the thalamus to create a feedback circuit (infragranular layers –> thalamus –> layer 4)
Information flow within the cerebral cortex is mediated by the action of the supragranular neurons while additional information from the internal and external environment is integrated by the thalamus to the 4th layer
Processes of memory
Encoding: acquisition of information “learning”
Retention: storage of information
Retrieval: accessing stored information
Temporal memory
3 classes
Short term memory: limited capacity that is limited over time
Working memory: similar to short term memory while using that information to plan and carry out action
Long-term memory: retention of unlimited information consolidated from short-term or working memory, unlimited time?
Working memory
Involves keeping relevant information accessible for short periods of time while a task is being completed
Operates in real-time
limited capacity: once thought to be 7 items but now only 4
Goal-directed action
distinct functions
Distinct functions of working memory
planning: developing and executing a strategy
selection and suppression: Identifyign relevant components of the task and focusing on that task
Task monitoring: keeping relevant information online and updating this info as the next step in the task is determined.
Brain regions involved in working memory
Requires activation of areas of brainstem utilized by teh 5 SSDNs which send projections to the thalamus Ascending Reticular Activating System (interlaminar nucleus and thalamic reticular nucleus) and the mediodorsal nucleus of the thalamus
The thalamic nuclei then communicate with regions of the prefrontal cortex
Prefrontal cortex and memory
Lateral PFC: RIGHT lpfc processes perceptual data and the LEFT lpfc processes symbolic data (language and semantic information
Medial PFC: processes positive emotion and positive emotional memory
Orbital PFC: processes negative emotion and negative emotional memory
Brain regions involved in attention
Five SSDNs
Tectum: Controls auditory and visual responses
Inferior colliculi - auditory stimulus
Superior collliculi - visual stimulus
Thalamic ARAS (Iln, TRn) and pulvinar nucleus of the thalamus: act as a relay station between the tectum and the 5 SSDNs and the cortex
Cingulate gyrus: Helps to maintain state of alertness
RLPFC: Working memory related to perceptual processing
Right Superior Parietal Lobe: Controls shift in attention Including shifts of attention between different spatial locations
Long Term memory major divisions
Declarative memory
Non-declarative memory
Declarative memory
Knowledge that we have concious access to and is known as explicit memory
Semantic memory: Knowledge about the world
Episodic memory: Knowledge about own life
Non declarative memory
Encompasses several forms of knowledge and is revealed when an individual performs a task that does not require intentional recollection
Procedural memory: learning of motor and cognitive skills
Priming: Memory that involves a change in response to a stimulus as a result of previous exposure to stimulus
Classical conditioning: Pavlov! A conditioned stimulus (Bell) is paired with an unconditioned stimulus (Salivating as a result of food) which results in an evoked response to conditioned stimulus (salivating at bell)
Nonassociative learning: requires simple forms of learning like HABITUATION (decreased response with overload of stimulus) and SENSITIZATION (Increased response with stimulus overload)
Patient HM and memory loss
Bilateral medial temporal lobectomy
Anterograde amnesia
cannot recall skills learned after surgery but CAN access non-declarative memory and working memory (small win!)
Lessons from HM
Functioning of the medial temporal lobe (MTL) was necessary for memory
The processes underlying storage of short-term and long-term memory are different
Two distinct categories of long-term memory exists: explicit (declarative) and implicit(nondeclarative)
Rats, hippocampus and memory test
Goal: find hidden platform in opaque water
Rats get better at the task with subsequent exposure
Rats with hippocampal lesions prior to learning are unable to improve
Rats with hippocampal lesions after learning are able to perform at the same level
HIPPOCAMPUS is needed for FORMATION but not for storage or retrieval
Medial Temporal lobe
Binds and keeps track of all relevant circuits used in working memory
Uses NT glutamate
Directs the consolidation of memory into long term storage by maintaining linking of all relevant networks so that they can be activated as a group later for recall
Major memory structures within MTL
Hippocampus: Mediates spatial memory (parahippocampal gyrus)
Amygdala: modulates the encoding and storageof hippocampal-dependent memories
Rhinal Cortex: Another card
Rhinal Cortex
Perirhinal cortex: Controls object recognition
Entorhinal cortex: Interface between neocortex and hippocampus. Important role in formation and consolidation of episodic and spatial memories. Sends projections to the dentate nucleus (hippocampal formation) that also helps with episodic memory formation
Two forms of Long Term Potentiation
Early LTP: synpatic changes for several minutes to 3 hours. Now new proteins were formed or change in synaptic morphology
Late LTP: 3-24 hours. New proteins within neuron, synaptic morphology changes observed.
Associativity
Induction of LTP by the stimulation of two sets of synapses that are activated concurrently
Thought to strengthen the connections between relevant information
Specificity
Phenomenon in which LTP is elicited at one set of
synapses on a postsynaptic cell, whereas adjacent synapses that were not activated do not exhibit LTP-like changes. Sight and smell of a rose will activate BOTH pathways even if only one is presented.
Nondeclarative memory characteristics
Memory without recall or awareness
Experience alters behavioral performance unconsciously
Evidence for implicit memories can be found in preferences, habits, and dispositions that are inaccessible to conscious recall (both during and after acquisition)
Implicit memory is not dependent on the MTL
Can be categorized into four subtypes: Procedural habit or skill memory Priming Classical conditioning Non-associative
Procedural/Habit or Skill Memory
Learning of a variety of motor and cognitive skills. Repeated rehearsal improves skill performance. Context specific
Damage to Basal Ganglia shows severe deficits
Priming
Change in response to a stimuli or the ability to recognize a stimulus as the result of prior exposure to that stimulus. A single activation of a network that readies it for learning occurs in the neocortex.
Previous exposure makes it easier to activate the same pathway
Even a single exposure to a cognitive item can greatly increase retesting
Classical conditioning responses
Skeletal muscle responses: motor control controlled by cerebellum
Emotional responses: Controlled by the nAC, amygdala, orbital/medial prefrontal cortex
Sensitization
Cues teh CNS about novel stimuli that may be essential for survival. Increased response to novel or harmful stimuli.
In sensory motor reflex pathways
STP and enhanced release of NT
Habituation
Ignore stimuli that have lost their meaining or novelty. Ignore begnin stimuli.
In sensory motor reflex pathways
STD
Exposure to noxious stimuli
after exposure to noxious stimuli all responses are heightened. If noxious is paired with a benign stimuli the benign will also have increased response
Intuition and emotion
Implicit memory processes involving emotion and “intuition”
Actually play a crucial role in an individual’s ability to make decisions. Non-conscious emotional signals may factor into decision-making before conscious processes do. These processes appear to be mediated by the ventro-medial prefrontal cortex (VM PFC).
Ventro-Medial Prefrontal Cortex
Responsible for the storage of past rewards and punishments
Triggers non-concious emotional responses
Ventro-Medial Prefrontal Cortex Lesions
Display little emotion in social situations and no empathy towards others
Perform well on IQ and memory tests but exhibit poor decision making ability
Have intact factual knowledge but emotional memories are absent
Exhibit dissociation of socially appropriate goal-directed (reward) behavior and willful behavioral action
PET scans of violent criminals and those exhibiting sociopathology showed abnormally low regional cerebral blood flow (rCBF) in all ventro-medial prefrontal cortical areas
