behavioral neuroscience exam 4

Arousal

Overall alertness

Attention (Selective attention)

is the process of selecting/focusing on one or more specific stimuli
→ Sensory input or internal thought
→ Overt vs. covert attention

Cocktail party effect

focuses cognitive processing resources
- Filter out distracters
- Enhance processing & analysis

Inattentional blindness

Failure to perceive non-attended stimuli

Divided-attention tasks

Attentional spotlight shifts around trying to extract the multiple important pieces of information

EARLY-SELECTION MODEL

▪ Level of sensory input/processing
▪ Filters out unimportant (non-attended) sensory
stimuli BEFORE perceptual analysis

LATE-SELECTION MODEL

▪ Level of higher cognitive processing
▪ Filters out unimportant (non-attended) sensory
stimuli AFTER perceptual analysis

PERCEPTUAL LOAD

Combination of early and late selection

→ Complex stimulus will lead to early selection
→ Simple stimulus will lead to late selection

Consciously- or endogenously-controlled attention

→ Attention shift comes from within
→ Allows for slower, longer-lasting, accurate attention

Top-down process

higher order processing controls sensory processing
▪ Covert and overt attention

Exogenously-controlled attention

→ Involuntary reorientation towards sudden or important event
→ Allows for very fast reaction time, but very brief (if irrelevant)

Bottom-up process

sensory inputs trigger higher order processing

sensory inputs trigger higher order processing here

thalamus, pulvinar, superior coliculus, and recticular activating system

pulvinar

- Thalamus
- Shifting of attention
- Isolates relevant information by
filtering out distractors (mainly covert attention, some overt)
- Mainly top-down processes

superior colliculus

- Implements planned eye movements
- Mainly overt attention, though some role in covert attention
- Also involved in reflexive attention
- Top-down and bottom-up processes

CORTICAL AREAS INVOLVED IN VOLUNTARY ATTENTION (DORSAL FRONTOPARIETAL NETWORK)

frontal eye field, visual areas, intraparietal sulcus/ superior parietal lobule, temporoparietal junction, ventral frontal cortex

frontal eye field (FEF)

- Premotor cortex
- Establishes gaze in accordance with cognitive goals (top-down processes)

intraparietal sulcus/ superior parietal lobule

- Controls voluntary shifts of attention
- Eye movement planning

temporoparietal junction

- Establishes gaze in accordance with characteristics of stimuli
(bottom-up)
- Shift happens after unexpected event

individual neuron during attention

▪ Peak firing rate increased (sensitivity)
▪ Firing shape sharpens (focuses spotlight and excludes distractors)
▪ Firing shifts to different preferred stimulus

Claustrum

seat of consciousness?
→ Reciprocal connections to almost all cortical areas
→ Stimulate it with strong pulse and lose conscious awareness

Cognitively impenetrable

neural processing that can’t be
simplified

Easy problems

objective conscious experiences

Hard problems

subjective conscious experiences
→ Decision-making and free will (executive function)

→ Can impact decision-making and free will (executive function)

EXECUTIVE FUNCTION

▪ Skills used to manage everyday thoughts, feelings, choices
▪ Rely on working memory, cognitive flexibility and inhibition control
▪ Direct attention to important stimulus/task
▪ Make a decision or formulate plan of action

Orbitofrontal PFC

goal-directed behaviors, signaling expected outcomes (green)

Dorsolateral PFC

judgement, planning, insight, working memory (blue)

Hormones

are chemical signals
→ secreted by specialized cells (e.g. glands)
→ travel widely (often bloodstream) to act on specific receptors
▪ Affect our reproductive behavior, feeding & drinking, stress &
emotion…

Endocrine glands

release hormones within the body

Exocrine glands

use ducts to secrete fluids/hormones such as tears
and sweat outside the body

The nervous system contains

endocrine glands and is the target of endocrine glands

Endocrine communication

a hormone is released into the bloodstream to act on target cells/organs

Paracrine communication

a released chemical diffuses to nearby target cells; no synapse involved

Autocrine communication

a released chemical acts on the cell that released it

Pheromone communication

→ hormones between individuals of
the same species

Allomone communication

→ hormones across species

GENERAL PRINCIPLES OF HORMONE ACTION

Hormones are released widely
→ effects determined by where receptors located
→ each organ may respond differently
▪ Hormonal signals can be slow (seconds to hours)
▪ Hormonal effects can be gradual and last up to weeks

Hormones modulate

behavior; don’t usually initiate/terminate it, Behavior can alter
hormone release

Hormone levels

cycle over day, month, lifetime...

SIMILARITIES BETWEEN HORMONES AND NEUROTRANSMITTERS

▪ Both systems synthesize, store and release chemical signals
▪ Both use specific receptors, often with intracellular biochemical pathways
▪ Both systems can affect behavior

Neurotransmitters travels to

precise destinations (because neurons are
connected via synapses)

Hormones spread

throughout body, but only act on cells with correct
receptor

Neural messages

are rapid, and hormonal messages are slower

Some chemicals can be

BOTH hormones and neurotransmitters

Neuroendocrine (or neurosecretory) cells release

hormones into the blood in response to action potential
▪ Hypothalamus

Peptide & amine

→ Metabotropic
→ cAMP, IP3, DAG
→ Seconds to minutes to take effect

Steroid & Neurosteroid

→ Nuclear receptor
→ Bind transcription factor
→ Hours to take effect

Hypothalamus: neuroendocrine cells secrete

peptide hormones into bloodstream of the posterior pituitary gland
▪ These same peptide hormones spread throughout
the body

Oxytocin

social bond formation (parents/offspring, sexual partners)
→ reproductive physiology, uterine contraction, and lactation

Vasopressin

thirst/water regulation
→ increases blood pressure and inhibits urine
formation

Hypothalamic neurons release “releasing hormones” into

median eminence blood vessels → called the hypophyseal portal
system

Releasing hormones are carried to

the anterior pituitary
→ anterior pituitary releases tropic hormones into blood stream

Tropic hormones spread

throughout body

HPA AXIS

A STRESS RESPONSIVE SYSTEM

hpa

Hypothalamus – Pituitary – Adrenal

The adrenal cortex/adrenal gland secretes

steroids, including glucocorticoids

Cortisol is a glucocorticoid hormone that

prepares the body to deal with stress
→ Increases blood glucose
→ Promotes metabolism
→ Suppresses inflammation

NEGATIVE FEEDBACK LOOPS

Detect, evaluate and regulate hormone levels and biological effects
▪ Hormone is steadily released, and once enough release the negative feedback signal gets sent
▪ Multiple levels of hormone release, multiple levels of negative feedback

WHAT ARE EMOTIONS?

▪ Subjective mental state
→ Feelings
→ Involuntary physiological changes caused by autonomic NS
▪ Verbal communication (words, tone of voice) and non-verbal communications (body language, facial expressions)

emotions continued

Help us deal with wide variety of
situations
▪ Facilitate social contact and learning

UNIVERSAL FACIAL EXPRESSIONS OF EMOTION

Facial expressions provide emphasis and context for
verbal communication

HUMAN EMOTIONS –BIOLOGICAL AND CULTURAL INFLUENCES

▪ Agreement about meaning of most facial expressions
▪ Non-literate groups had trouble with disgust and
surprise

Emotional reactivity

measured in infants (heart rate, blood pressure, tears)
→ 40% low; 20% high
→ similar responses throughout life

High reactive children

shy, risk averse, exaggerated amygdala responses, greater risk for anxiety disorders

Low reactive children

outgoing, fearless

WHAT DRIVES EMOTIONAL RESPONSES?

▪ Physiology drives feelings
→ Botox
▪ Feelings drive physiology
→ Smile
▪ Cognitive analysis drives emotional responses
→ Epinephrine studies

Electrical stimulation studies

→ Brain self-stimulation (reinforcing or aversive)
▪ Positive emotion elicited by stimulating medial forebrain bundle

CIRCUIT 1: MEDIAL FOREBRAIN BUNDLE

The medial forebrain bundle (MFB) connects the ventral tegmental area and the nucleus accumbens. For drug abuse, this circuit is central because the VTA releases dopamine into the NAc, which produces feelings of pleasure and reinforces drug-seeking behavior

CIRCUIT 2: LIMBIC SYSTEM

▪ Negative emotion elicited by stimulating limbic system
→ Amygdala :
- anxiety, stress, fear

PATIENT S.M.

Developed fearlessness in childhood
→ Outgoing, but few good friends
→ Confronts risk
→ Low sympathetic NS responses

Calcium deposits in

amygdala, causing patient sm’s amygdyla to detoriate

patient sm had Strong panicky fear in response to

physiological challenge

External threats detected by

amygdala

Internal threats detected by

brainstem

HOW DOES THE AMYGDALA DETECT EXTERNAL
THREATS?

low road and high road

Low road

allows for immediate responses, Sensory information travels from the thalamus directly to the amygdala, bypassing the more complex processing of the cerebral cortex.

high road

allows for higher level cognitive
processing
→ PFC allows for observational fear learning

Sympathetic NS stress response

→ Norepinephrine released from adrenal medulla
→ Fast

HPA axis response to stress

→ Cortisol released from adrenal cortex
→ Slow

Stress immunization

Early stressful experiences can
allow for later resilience. Can be coupled with a parent/caregiver giving comfort after a stressful event.

More significant early life stress

→ Greater stress responses
→ Learning deficits
→ Long-lasting changes in brain
– less adult neurogenesis
– less adrenal steroid receptors

Negative affect

experiences world in negative terms
→ Higher levels of distress, anxiety, dissatisfaction
→ Low subjective sense of well-being
▪ Genetic risk (many genes contribute to susceptibility)
▪ Chronic, lower grade stressors increase risk for anxiety disorders
or depression

Alarm

body mobilizes to confront threat

Resistance

body actively copes with threat

Exhaustion

if threat continues the body’s resources become depleted

DYSREGULATION CAN LEAD TO NEGATIVE AFFECTIVE
DISORDERS

▪ Chronic stress produces excess alarm and resistance
▪ Contribute to development of negative affective
disorders

Generalized anxiety disorder

chronic anxiety, exaggerated tension

Obsessive-compulsive disorder

recurrent unwanted thoughts (obsessions)
and/or repetitive behaviors (compulsions)

Panic disorder

unexpected, repeated episodes of intense fear and physical
symptoms

Posttraumatic Stress disorder

memories of unpleasant event produce same intense visceral arousal

Social anxiety disorder

overwhelming anxiety and excessive self-consciousness in everyday social situations

PTSD patients have

smaller hippocampi (HPC)

smaller hippocampi (HPC)

correlates A TYPE OF LEARNED FEAR

Fear conditioning

Tone is associated with mild electrical shock
▪ Eventually tone alone elicits “freezing” response

Chronic, unpredictable stressor (tone) will continue to elicit “freezing

Original trauma activates

1. alarm stress systems
2. amygdala

step 2 of ptsd model

Subsequent stressors produce heightened alarm stress response

step 3 of ptsd model

Triggers traumatic memory (via amygdala)

last part of ptsd model

Over time, traumatic memory associations and
physiological response are strengthened

brain changes due to depression leads to Greater brain activity in

PFC and amygdala
- Persists after depression period over
- Electroconvulsive therapy/repetitive
transcranial magnetic stimulation

depression leads to

Smaller hippocampus