Intro to Cognitive Neuroscience Exam #1

Cognition

variety of higher mental processes (thinking, perceiving, imagining, speaking, acting, planning, etc.)

Neuroscience

biological investigations of the brain and the nervous system

Cognitive Neuroscience

the intersection of cognitive science, cognitive psychology, biology, and neuroscience

Dualism

• the philosophical or theological view that reality, a domain, or a specific problem can be divided into two fundamental, irreducible principles or substances

• Rene Descartes said that “spirits” flow through ventricles of the brain

Pineal Gland (in relation to dualism)

Believed to be the connection between the immortal mind and the physical/mortal body

Phrenology

Discredited 19th century pseudoscience that claimed an individual’s personality traits and metal faculties could be determined by measuring the bumps and depressions on their skull

Phrenologists

• Franz Joseph Gall and Johann Spurzheim (early 19th century)

• 35 areas (different functions)

• brain grows to accommodate functions

• anatomical personology

Results of Jean-Pierre Flourens

• removed localized portions of cortex and noted their effects on bird behaviors

• all sensations, all perceptions, and all volitions occupy the same seat in these cerebral organs. The aculty of sensation, perception and volition is then essentially one faculty

• aggregate field (mass action)

Jacksonian seizures

originate in the motor cortex and cause abnormal movements or sensations on just one side of the body

Neuron doctrine

• the fundamental scientific principle hat the nervous system is composed of discrete, individual cells rather than a continuous, fused network

• neurons are the basic functional units of the brain

• these basic building blocks can be studied to understand how the mind works

• by the 1900s, the neuron doctrine began to gain acceptance, and some form of localizationalism was broadly accepted

Brodmann and cytoarchitecture

consistent with localizationalists, different cytoarchitecture corresponds to different functions

Marr’s 3 levels: level 1

computational level, the goal

• what’s the purpose of the behavior

• in computers: what does the program do?

• not WHAT the computation is, but WHY

Marr’s 3 levels: level 2

algorithmic level, the method

• what are the processes, steps, etc.

Marr’s 3 levels: level 3

implementation level, the substrate

• what runs the algorithm?

• neural structures, silicon, etc.

Phineas Gage

• got an iron rod straight through his skull

• before the accident, he was known as a hardworking, efficient and smart businessman

• after the accident, he became impulsive, profane, and struggled to maintain employment

• Impact: provided early evidence for brain localization and the frontal lobe

Henry Molaison

• faced with uncontrollable seizures, he had a neurosurgeon remove parts of his temporal lobes including the hippocampus, amygdala, and surrounding cortex on both sides of his brain

• it cured his epilepsy, but it caused him to develop severe anterograde amnesia and be unable to develop any new long-term memories

• Impact: proved that the hippocampus is required to transfer short-term experiences into lasting experiences and showed that there are multiple, distinct memory systems

rostral

a

dorsal

b

caudal

c

ventral

d

slice orientation

sagittal

slice orientation

coronal

slice orientation

transverse

brain viewpoint

ventral

brain viewpoint

medial

brain viewpoint

lateral

brain viewpoint

dorsal

layers of the brain

skull, dura, gray matter

gyrus

bump

sulcus

groove

compsition of gray matter

cell bodies of neurons and glia (nerve glue)

composition of white matter

myelinated axons

purpose of the folded cortex

increase surface area (gyri and sulci) and reduce axonal distance

frontal lobe

• front of the brain, largest lobe

  • decision-making, problem-solving, reasoning, volunatry movement, language production (Broca’s area), and personality

temporal lobe

• sides of the brain

  • processing auditory information (hearing), language comprehension (Wernicke’s area), memory encoding, and emotion

parietal lobe

• top and back of the head

  • processing sensory information like touch, temperature, pressure, and pain; spatial awareness and navigation

occipital lobe

• back of the brain rests on the base of the skull

  • Processes visual information, including color, shape, recognition, and spatial perception

what are the brain ventricles for

to produce, store, and circulate cerebrospinal fluid

motor and somatosensory homunculi

a distorted visual map of the human body laid across the cerebral cortex, showing how much brain space is dedicated to different body parts

association cortices

• multiple sensory modlities

• integrate sensory and motor

• allocating attention

what is cognitive psychology

• the construction and reconstruction of biologically relevant aspects of the external world

  • not always isomorphic relationship world/perception

  • emphasis on costruction (assumptions about the structure of the world)

  • to reconstruct, sometimes decisions are arbitrary

• study of mental activity as information processing problem

• internal (metal representations)

chronometrics

• measure reaction time

• finer analysis of internal representations

• handle on mental events which are rapid and efficient

serial processing

tasks sequentially, one after another

parallel processing

executes multiple tasks simultaneously using different resources

stroop effect

• a delay in reaction time that happens when the meaning of a word clashes with the color of its ink

• reduction is response in manual, not verbal

• reduce interference with dual task or with practice

eye tracking

use eye movements/gaze patterns to tap into mental processes

basic uses of eye tracking

• where are they looking?

• how frequently do they make saccades?

• do they reurn to previously fixated locations?

• fixation monitoring (if you don’t want them to wander)

• gaze-dependent stimulus presentation

purpose of computer modeling

• computers represent and transform information

  • good model for studying human cognition

• ai: simulate human behavior

  • examine representation

  • examine info transformation

• representations:

  • symbolic entities or subsymbolic

  • neural netowkrs

  • best mapping between input and output

limitations of comupter modeling

• simplification

• not quite neuron-like; non-linear activation but not really biological

• small in scale, narrow problems

intracellular recording

very difficult, graded membrane potentials (ask: how close re we to spiking?)

extracellular recording

more common, action potentials (“spikes”)

relevance of a neuron’s baseline activity

• neurons are constantly active

• measure changes to experiemntal manipulation

• what increases or decreases firing rate?

receptive field

the specific region of sensory space (like an area of skin or a patch of the visual field) or the set of input data that can change the electrical activity or response of a particular neuron

raster plots

present visual depictions of how frequently an electrode records a spike

pros of single-cell recording

excellent spatial and temporal resolution (“gold standard”)

cons of single-cell recording

• limited spatial coverage

• are single neuron(s) representive of the whole region?

• not human

• not causal

complex cell preferences

complex cells in the visual cortex prefer oriented edges or light patterns moving in a specific direction, responding regardless of the exact position or polarity (light vs dark bar) within their receptive field

animal lesions

• neural structure contributes to the task

  • lesions → impairs performance on task

  • is brain region necessary for task?

• some caveats

  • area may be bypassed to other regions and not be involved itself

  • animal may learn to compensate for deficit, so the system is reorganized

animal lesions: what techniques can be used?

• aspirate tissue: destroy brain structure via suction

• electrolyte lesion: similar, using electrical charge

• neurochemical lesion: designed to damage specific cell types only)

• reversible lesion

  • cooling (i.e. via cooled methanol pump)

  • pharmacological

    • i.e. scopolamine

genetic manipulations

• genome mapped

  • not completely understood yet

• goal: to find genetic basis for brain disorders

• approach: produce genetic alterations in animals

  • “knockout” mice

what is CT

• computed tomography (CT)

• like x-ray but from all possible directions

  • many more images = more radiation exposure

• intervening tissue absorbs radiation (bone a lot; blood a little)

• reconstructs differential absorption

MRI

properties of hydorgen spin are measured

EEG

recorded from scalp electrodes

DTI: why diffusion is relevant

tracking the microscopic, random motion of water molecules acts as a natural probe to map the structural wiring and organization of brain tissue

DTI: what it is used to estimate and measure

uses MRI to measure diffusion of water through axons