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Daily Responses

Peter Vincent and Sarah Olesen

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The Everyday Brain and Our Everyday Life

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The Neurobiology of our Everyday Brain

Example: We will “follow the process” from waking up to making some tea

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The Sleep-Wake Cycle

What is circadian rhythm?

Suprachiasmatic nucleus (SCN): body’s master clock

Brief overview of circadian rhythm and circuits in the brain - circadian biological clock (SCN = body’s master clock) - the body’s internal clock is controlled by an area of the brain called the suprachiasmatic nucleus - located in the hypothalamus

Circadian rhythms are 24-hour cycles that are part of the body’s internal clock, running in the background to carry out essential functions and processes - one of the most important circadian rhythms is the sleep-wake cycle

Random shit:

Most animals follow the cycle of daily natural light. It controls many behaviours. Eating, sleeping, mating. Hormonoes secreated like testosterone and hormones for eating are connected.
Retina is connected to SCN - activation of retina, reduces melatonin? When we are awake our memory is better, concentration, we are more alert
Even plants have biological clocks
SCN has some slightly complicated internal molecular pathways with includes the production and breakdown of proteins which are thought to take 24hrs to happe, thus allowing SCN to keep an internal clock
SCN has receptors for melatonin? Or it releases melatonin
Circa diam - about a day
If you remove SCN into tissue then it still keeps its internal clock
Phones effect melatonin and can mess with you feelings of tiredness in the evening.

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The Sleep-Wake Cycle

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Decision-making:

shall I make a cup of coffee (or tea) this morning?

The Reward System

Our everyday life is full of decision dilemmas and uncertainties, from the most ordinary decisions, for example as in this lecture, whether to put the kettle on the stove? - to life-changing decisions, such as whether I should take this job or not? But how does the brain make decisions?

The answer to this question is still very much up for debate, and is vastly complex. The circuits in the brain involved in decision-making are only partially understood because even the most mundane of decisions involve many brain areas and cooperative interactions between many cells.

What do we know about how the brain makes decisions? You generally seek things that are nice, and avoid things that are not nice, and every day, in fact, that’s what you’re doing everyday, making these tiny little decisions.

The first step - processing sensory information (visual info through the eye for example)

Sensory information is communicated to your reward system

In turn, the reward circuitry, which releases the molecule dopamine, will help motivate the choice of your next action. In our example, thirst info from the brain stem?

The frontal areas of the brain, which are thought to control cognitive skills such as judgement and problem solving, play a role in helping you make the decision to have a cup of coffee (and the frontal cortex also controls the selection of such a voluntary action as moving your arm to put the kettle on for your cup of coffee - which we will go into a bit later)

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Vision: how does the eye work?

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Vision: the retina

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Retinal fireworks

Josh R Hanes, Harvard

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Vision: from the retina to the visual cortex in the brain

Primary visual pathway

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Visual processing: ventral stream

Primary

visual cortex

Dorsal stream

Ventral stream

What?

Object recognition
Discrimination of objects

“Cup of coffee? A kettle?”

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Visual processing: dorsal stream

Primary

visual cortex

Dorsal stream

Ventral stream

Where?

Object location
Orientation of objects

“Where is the kettle?”

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Sensory-based coordinates to

effector-based coordinates

A part of the dorsal stream: spatial representation of objects

Receives multimodal sensory inputs

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Action selection

How do we carry out goal-directed movements?

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Action selection and control: basal ganglia

How do we carry out goal-directed movements?

Group of subcortical nuclei
Executes smooth movement

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Action execution and control: motor cortex

How do we carry out goal-directed movements?

Somatotopic representation of motor outputs:

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Muscle activation:

our arm reaching out to put the kettle on

Corticospinal tract:

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Proprioception:

our arm muscle proprioceptors feeling that the kettle is now supported by the stove

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Summary

Wake Up

Circadian Rhythm�Suprachiasmatic nucleus

Pick Hot Drink

Decision-making�Distributed brain areas

Find Kettle

Visual processing�Retina�Ventral stream (what?)�Dorsal stream�(where?)

Reach for Kettle

Action selection�Frontal and temporal lobe
Action execution and �control�Basal ganglia�Motor cortex�Corticospinal tract
Proprioception�Sensors in muscles and �joints

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Questions?