Midterm 4 - Brain and Behavior pt 2

Emotions

a fleeting subconscious, physiological response (expression) in reaction to an event; 6 universal emotions include fear, anger, joy, sadness, disgust, and surprise

Feelings

how one is feeling inside of their body, is not always related to emotion, involves cognition, and can be hidden

James-Lange Theory

theory that a stimulus is perceived, causes an emotional expression, and is then perceived cognitively to create an emotional experience (feeling linked to an emotion)

Cannon-Bard Theory

theory that a stimulus is perceived, causes an emotional experience (feeling linked with emotion), and then allows us to act out an emotional expression

Volitional smile

a voluntary smile that does not reflect genuine emotion and is generated by the pyramidal motor pathway (ex. forcing a smile for a photograph)

Duchenne smile (emotional smile)

an involuntary, emotional smile that reflects true emotional experience and is generated by the extrapyramidal motor pathway (ex. smiling in response to a funny joke)

Pyramidal motor pathways

motor pathways that innervate voluntary, skeletal muscles via upper motor neurons

Extrapyramidal motor pathways

where neurons do not originate in the motor cortex, but instead from areas like the brainstem and hypothalamus, creating a closer association with emotions

Hypothalamus

controls hormones secretion via connections to the pituitary gland, and regulates autonomic expression of emotions and innate and conditioned defensive behaviors

Amygdala

responsible for relating sensory stimuli with emotional experience and is required for high order processing of emotion

Patient S.M

physically unable to feel fear or recognize fear in facial expressions due to bilateral lesions of the amygdala - can still be startled and follow group fear response

Emotional learning

the construction of implicit memories linking a situation or event to an emotional body state (most emotional responses are learned)

Fear conditioning

requires the amygdala to show appropriate fear response and the hippocampus to help us predict dangerous stimuli (factual learning)

Emotional symptoms of anxiety

include irrational and excessive fear or worry, panic, feelings of dread, irritability, restlessness, etc

Physical symptoms of anxiety

include shortness of breath, muscle tension, headaches, sweating, etc. (all are manifestations of our fight or flight response)

Role of sympathetic nervous system on anxiety

many signs of anxiety are explained by sympathetic nervous system activation such as increased heart rate and blood pressure, dilation of pupils, sweating, etc

Panic attack

sudden episodes of discrete periods of intense fear or discomfort accompanied by four or more symptoms such as trembling, numbness, dizziness, chest pain, etc.

Locus ceruleus

area of the brain in the brain stem that is involved in fear which is responsible for producing norepinephrine

Norepinephrine

a neurotransmitter and hormone that plays a critical role in the body’s fight or flight response and regulating physical reactions to stress

Hypothalamus

area of the brain involved in fear and is responsible for triggering the sympathetic nervous system to prepare the body for perceived threats

Necessary parts of the brain

proven to be necessary because without that region, a certain behavior is not presented

Sufficient parts of the brain

proven to be sufficient because when everything but this area is removed, the behavior is still presented

Anxiolytics

drugs used to relieve both the psychological and physical symptoms of anxiety by enhancing GABA receptors so that more hyperpolarization can take place and prevent overactive hypothalamus from firing AP (ex. xanax, valium)

Mesolimbic dopamine pathway

pathway between the ventral tegmental and nucleus accumbens that acts as the primary reward synapse in the brain and increases motivated behaviors

Ventral tegmental area (VTA)

source of dopamine cell bodies that send axon projections to the nucleus accumbens

Nucleus accumbens

receives dopamine inputs from the VTA and uses the signal to reinforce behavior that increases dopamine release

Basal ganglia

increases motor output to produce an overall increase in behavior and assist with habit formation

Hippocampus

provides our nucleus accumbens with contextual memory to help us remember where rewards are found

Prefrontal cortex

provides the nucleus accumbens with options to create plans on how to achieve rewards

5 major brain regions involved in reinforcement

ventral tegmental area, nucleus accumbens, basal ganglia, hippocampus, and prefrontal cortex

Dopamine neurons in the VTA can change because…

when a conditioned stimulus is presented with a reward, the VTA will fire for the conditioned stimulus instead of the reward - without the reward, the neural activity in the VTA will be suppressed

Effects of drugs on reward synapse

all drugs exponentially increase dopamine release in the nucleus accumbens, causing down regulation of our dopamine receptors so dopamine release for natural rewards no longer feels rewarding

Positive symptoms for schizophrenia

Delusions, hallucinations, disorganized speech, paranoia, etc.

Negative symptoms of schizophrenia

Decreased motivation, diminished emotional recognition and expression, social withdrawal, etc.

Causes of schizophrenia

mostly include genetic heredity (80-85%) of susceptible genes, but can be caused by environmental factors such as stressful childhood events, prenatal and birth complications, cannabis use during adolescence

The dopamine hypothesis

1) Elevating dopamine in normal individuals produces schizophrenia-like symptoms

2) Increasing dopamine in schizophrenia individuals worsens symptoms

3) Blocking dopamine activity in schizophrenics reduces symptoms

4) Excess dopamine in the mesolimbic DA pathway causes positive symptoms

5) Deficit of dopamine in prefrontal cortex causes negative symptoms and cognitive impairment

Schizophrenia treatments

drugs used to reduce positive symptoms of schizophrenia by reducing dopamine activity in the mesolimbic pathway, however, side effects include Parkinsonian-like symptoms or development of tardive dyskinesia (irreversible)

Patch Clamp recordings

method of measuring neuronal activity that allows us to directly measure action potentials, synaptic currents, and membrane properties; drawbacks include being highly invasive, and only being able to measure one neuron at a time instead of showing network-level dynamics