Neuroscience 2

Neuraxis

Dorsal - top of neuraxis

Ventral - bottom of neuraxis

Rostral - front

Caudal - back

Phineas Gage case

A historic brain injury showing that damage to the frontal lobe can dramatically alter personality and behavior.

Advantage of lesion studies

Reveal relationships between brain structure and function.

Limitation of lesion studies

Brain regions are highly interconnected so lesions often affect multiple behaviors.

Penfield’s stimulation studies

Electrical stimulation during surgery showed specific brain regions are responsible for specific functions.

Single cell recording

A method using a microelectrode inserted into nervous tissue to record activity from a single neuron during a task.

Computed tomography (CT)

Structural imaging technique using X-ray slices to produce images of the brain. Useful for diagnosing brain injuries

CT scan limitation

Relatively low resolution compared to MRI.

Magnetic resonance imaging (MRI)

Structural neuroimaging technique using magnetic fields to create high-resolution brain images.

MRI limitation

Time-consuming and expensive.

Positron emission tomography (PET)

Functional imaging using radioactive tracers to measure brain metabolic activity. The more active the area of the brain, the more metabolic resources will be used.

PET scan limitation

Invasive due to radioactive tracer injection.

Functional magnetic resonance imaging (fMRI)

Measures the use of oxygen throughout the brain and operates assuming that more active areas of the brain require more metabolic resources.

fMRI limitation

Oxygen use in the brain spikes a few seconds later after activity

Not the best method if researcher wants to capture the precise timing of brain activation and function

Electroencephalogram (EEG)

Electrical activity of the brain can be recorded through the scalp by wearing a cap of sensitive electrodes.

Brain regions

Forebrain, midbrain, hindbrain

Hindbrain

Brain region involved in basic life functions and movement coordination.

Hindbrain Structures include:

Reticular formation, cerebellum, medulla, pons

Reticular formation

Regulates arousal and motivation, circadian rhythms, posture and balance

Cerebellum

Facilitates coordinated movement.

Medulla

Controls autonomic functions such as breathing

Pons

Involved in movement, auditory perception, emotional processing

Midbrain

Small brain region involved in sensory processing and motor control.

Tectum

Midbrain structure involved in visual (superior colliculus) and auditory processing (inferior colliculus)

Tegmentum

Midbrain structure that contains red nucleus (motor control) and substantia nigra (reward center, dopamine)

Forebrain structures:

Hypothalamus, pituitary gland, amygdala, hippocampus, thalamus, cortex

Hypothalamus

Stress response, energy metabolism, four F’s (fight, flight, feeding, reproduction)

Pituitary gland

Master endocrine gland under hypothalamic control.

Anterior pituitary

Receives signals from the brain via the hypothalamus and releases stimulating hormones to other important endocrine glands

Posterior pituitary

An extension of the hypothalamus that releases two hormones called oxytocin and vasopressin

Thalamus

Relay station for all senses except smell.

Amygdala

Receives sensory information and decodes emotions. Receives stimuli that may be threatening, associated with PTSD.

Hippocampus

Short term memory, navigation, one of the few regions in the brain where neurogenesis continues throughout adulthood

What condition do we see accumulated damage to hippocampus?

Neurodeneration in Alzheimer’s where it leads to amnesia

Cerebral cortex

Thin outer layer responsible for controlling information processing and cognition

Limbic system Structures

PHAT-H

Gyri

Cortical ridges that increase surface area linked to specific mental functions

Sulci

Cortical grooves that separate functional regions like longitudinal fissure for left and right hemisphere

Frontal lobe

Processes complex decision making and “higher-order thinking”

Responsible for complex functions such as language, inhibition (restraint), manipulation of items in short-term memory.

Occipital lobe

Exclusively processes vision

Handles most basic visual input and some complex input

Functional blindness

condition where an individual can physically see but is not able to process what is happening around them, therefore “blind”

Temporal lobe

Processes form and identity of visual stimuli

Location of primary auditory cortex where auditory processing begins

What can damage in the temporal lobe result in?

Deficits in memory, auditory processing, production of speech

Parietal lobe

Processes touch, involved in complex visual and spatial functions

What can damage to parietal lobe result in?

Deficits in orientation, attention, coordination of targeted movements

Brain lateralization

Specialization of functions to one hemisphere of the brain.

Broca’s Area

Left frontal lobe responsible for motor production of speech

Expressive aphasia

Damage to Broca’s area where you cannot properly articulate your words

Wernicke’s Area

Left temporal gyrus responsible for language comprehension

Receptive Aphasia

Damage to Wernicke’s Area where you struggle to understand language and often speak meaningless sentences, words are pronounced fluently and phrases seem to have normal rhythm and grammar.

Corpus Callosum

Thick bundle of axons which allows for communication of the two hemispheres of the brain

Split brain syndrome

Where corpus callosum is severed leading to two independently operating hemispheres

What happens when objects are presented to different visual fields in split-brain patients?

Objects in the left visual field are processed by the right hemisphere, which cannot verbally identify them but can recognize them through touch due to spatial and visual specialization, while objects in the right visual field are processed by the left hemisphere, which can name them but cannot identify them well through touch.

What do split-brain object recognition experiments demonstrate?

They show brain lateralization, where the right hemisphere specializes in spatial awareness and visualization and the left hemisphere specializes in language and naming.

Theory of Mind

The ability to attribute mental states (beliefs, intents, desires, emotions, knowledge) to oneself and to others

Mirror and Motor Neurons

Mirror neurons which fire after watching someone perform an action and then you perform it

Treatment for Phantom Limb Pain

Patients with phantom limb look at their non-amputated limb in the mirror and clench and unclench it over and over again and the pain subsides because for humans, “seeing is believing”

Capgras Delusion (what is it and cause)

Belief that an identical person has replaced a person close to him/her caused by damage to the visual processing stage involved with assessing the emotional significance of faces.

Hemi-Spatial Neglect

Ignoring half the world due to damage to right parietal lobe

Ablation Studies

Studies that remove part of the brain in order to study the results.

Declarative Memory

Also known as explicit memory; refers to memories that can be consciously recalled such as facts and knowledge.

Eloquent Cortex

Areas where damage would lead to paralysis, loss of language ability, or loss of sensory processing.

Metencephalon

Subdivision of the brain consisting of the cerebellum and the pons.

Myelencephalon

Subdivision of the brain consisting of the medulla oblongata.

Phrenology

Determining character and mental abilities based on the shape and size of the cranium.