# Behave

To understand about brain, one has to understand bio behind it, the culture and everything in between.

1. We have similar impulses/mechanism
2. We trigger those mechanism in new/imagined circumstances
3. We really are different in how we can respond to circumstances in complicated ways.

Consider brain as hardware, and experience, culture etc as s/w. Now consider a setup where software can change hardware (usually slowly, but sometimes enough for people to consider it abnormal). And consider hardware, which has so many settings, that no two hardware are exactly similar.

Not think of a hardware and software which co-evolves, with feedback from each other. And accentuating, the quirks each has, as long as the environment they live in, doesn't punish them for it.

[TOC]

# Chap One: Behavior
Words (like aggression) have many meanings. Opposite of love is not hate, but indifference.

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# Chap Two: One Second Before
Brain -> final pathway that mediates influences of all distal factors.

Those factors affect brain, which produces the behavior.

## Three metaphorical layers

1. Automatic (regulatory)
midbrain and brain-stem region, along with projects down the spine and out to the body, are collectively termed *autonomic nervous system*
2. Emotion
3. Cognition

But all interconnected.

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### Limbic system (emotion)
amygdala, hippocampus, septum, habenula, and mammillary bodies

*Limbic system* -> *hypothalamus* -> (influences autonomic functions) *layer 1*
*Limbic system* -> *hormones*

#### autonomic nervous system
##### SNS (sympathetic nervous system) (where body needs to be active)
releases norepinephrine (adrenal gland releases epinephrine)
##### PNS (parasympathetic nervous system) (where body can spend time digesting, vegetative states).
releases acetylcholine

### Limbic system & Cortex
*Layer 3* -> frontal cortex -> *Limbic system*

Cortext - [temporal, parietal, occipital, frontal]

amygdala, frontal cortex, mesolithic/meso-cortical dopamine system.

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## Amygdala
Has a lot to do with aggression.

Fear, anxiety, aggression. Uncertainties/unsettling. Non-confirming.

Amygdala -> ancient, innate fear
BLA (basolateral amygdala) -> recent, cortex like, learned fear.

opposite conditioning for learned fear happens with frontal cortex sending signals to BLA for inhibiting excitatory neurons.

uncertainty, unsettled yearning for a potential pleasure, the anxiety and fear and anger that the reward may be smaller than anticipated, or may not happen.
About not having expected/favourable outcome.

### Amygdala inputs
**Sensory inputs** (especially BLA). Fast pathway. Stronger pathways. eg emotional facial expressions. Approximate.

**Pain inptus** unpredictable pain. PAG?

**Disgust** insular cortex (part of prefrontal cortex). rancid food, moral disgust etc. us and them (related to disgust).

### Amygdala outputs
**all above**
**hippocampus** filtering what's relevant to learn
**motor outputs** combined with input paths, might lead to approximate, quick but wrong actions.
**arousal**

* hypothalamus then ANS
* locus coeruleus (brains SNS).

Autonomic feedback influences the *intensity* of feelings.

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## frontal cortex

involved with working memory, executive functions (organizing knowledge strategically and initiating action based on an executive decision), gratification postponement, long term planning, regulation of emotions, reining in impulsivity.

involved in harder things, when they are the right thing to do.

Evolution: recent (many of the recent genes are active in frontal cortex). And expression patterns of these genes are more than others, at individual person level.

Structure: more complex wiring, and bigger.

Growth: last to mature. Most recent evolutionary part evolving later.

Cells: has unique cells (compared to rest of the brain, among all species)

**spindle neuron** (common to socially complex species). two regions of frontal cortext: insula (disgust), anterior cingulate (empathy).

### subregion

#### The Frontal Cortex and Cognition
##### PFC (the decider)
- contextual information and action (area code)
- focusing on task
- executive (observe, analyze and act)
- categorical thinking
- makes us consider options (effortful)

#### Frontal Metabolism and an Implicit Vulnerability
frontal cortex tracks rules, evaluates rules, learns rules (don't pee).

Q: is FC involved even after rule is learned.
A: transfers to more reflexive brain (cerebellum)

generalist (meta). deliberate

high metabolic rate.

high load ->
* less performant later
* less social, less emotional regulation

easier to be truthful

#### The Frontal Cortex and Social Behavior
difference in PFC activation based on self or other. Tracks for reward-driven and advice driven.

bigger social group -> larger FC
fission-fusion (where social group could change in size and composition).
part of PFC larger based on individuals social group, in humans.
involved with difficult things, in social context

REM sleep, FC is offline

#### The Obligatory Declaration of the Falseness of the Dichotomy Between Cognition and Emotion

**dlPFC - cognition**: rational, cognitive, utilitarian, unsentimental
**vmPFC - emotion**: connection with limbic system (behavior feedback)

activations inversely proportional. but sometimes synchronized (complex tasks).

#### The Frontal Cortex and Its Relationship with the Limbic System

fear re-learning: hippocampus -> PFC -> BLA

regulating emotions with thoughts
**thinking differently** is different from **suppressing thinking**

think differently (antecedent strategies) *placebos*
suppress thinking (response strategies)

stress in frontal cortex
1. X is **very** important
2. do X or not do X

Stress, distraction, cognitive load make the two streams dissociate.

Final points:

- in-group prosocial when emotions/intuitions dominate,
out-group prosocial when cognition domoniates
- PFC not always about imprudent behavior (eg pulling trigger)
- varies among individuals. metabolic rate varies by appox 30x
- "Doing hard thing, when its right thing to do", right -> neurobiological sense
- eg good liars -> larger PFC white matter.

## The mesolimbic/mesocortical dopamine system

### Nuclei, Inputs, and Outputs

Synthesized in multiple brain regions (dopaminergic neurons).

- One helps initiate movement (parkinson's disease).
- Regulates release of a pituitary hormone.
- tegmentum (near brain stem) -> accumbens (limbic-ish), amygdala, hippocampus.

circuitry:

dopaminergic system {
**mesolimbic dopamine pathway**: tegmentum projects to accumbens and other limbic areas.
**mesocortical dopamine pathway**: tegmentum projects to PFC (but not to other cortical areas).
}

accumbens -> movement regions

back projects to tegmentum and/or accumbens (amygdala and PFC).

### Reward