Presentation is loading. Please wait.

Presentation is loading. Please wait.

The Rise of Homo sapiens: Chapters 1 & 2

Similar presentations


Presentation on theme: "The Rise of Homo sapiens: Chapters 1 & 2"— Presentation transcript:

1 The Rise of Homo sapiens: Chapters 1 & 2
Introduction and The Brain

2 Introduction Modern humans evolved in Africa
≈ 70,000 years ago → modern humans began to migrate They eventually moved into Europe, where they shared the continent with Neanderthals for several thousand years. ≈ 25,000 years ago, the last Neanderthal died. Ultimately, they became the only humans on Earth. What was the cause of their success? Not technology or their physique Perhaps their mental abilities

3 Introduction Phineas Gage → tamping rod through frontal lobe
Before accident-- responsible, dependable, smart business man After-- capricious, profane, irritable Dr.– “…persistent in executing all his plans of operation.” Executive functions: making decisions, forming goals, planning ahead, ability to change plans

4 Introduction 1st leap in cognition → 1.5 million years ago
Evolution of Homo erectus Movement away from safe, wooded habitats Changes in social life and landscape use Perhaps facilitated by physiological changes in sleep patterns 2nd leap in cognition → 100,000 – 40,000 years ago “modern thinking” Personal ornaments, art, elaborate rituals, scheduled hunting Explained by enhancement in working memory capacity

5 The Brain Edwin Smith papyrus
Earliest written evidence about the brain & behavior ≈ 2700 BCE (Origin is a mystery) First known use of the term “brain” Broca’s aphasia Internal head injury (localization)

6 Brain Ontogeny Cell proliferation: multiplication of cells
Until the 20th week Migration: cells moving to their programmed location Until the 29th week Differentiation: developing a specific function Continues until after birth Apoptosis: cell death Until the first 10 years

7 Brain Ontogeny Left hemisphere Right hemisphere
Language Right hemisphere Non-verbal & visual-spatial fuctions Separated by a major fissure Corpus callosum

8 Brain Ontogeny Frontal lobe Parietal lobe Temporal lobe Occipital lobe
Brodmann’s areas Divides brain into 52 regions, based on cell type and function

9 Brain Ontogeny Frontal lobe
Bordered by the lateral fissure and central sulcus (Executive) functions: Future planning Decision-making Problem-solving Broca’s area Damage Broca’s aphasia Personality changes

10 Brain Ontogeny Frontal lobe (cont’d) Cingulate cortex
Attention, especially short- and long-term goals Prefrontal cortex Dorsolateral prefrontal cortex: selective attention, task organization, planning, flexibility Orbitofrontal: processing of emotions, decision-making in social interactions Ventromedial: central part of the orbitofrontal cortex, located in the middle of the brain

11

12 Brain Ontogeny Parietal lobe Posterior to the central sulcus
Function: visuospatial processing Somatosensory cortex Controls senses, especially touch Damage: apraxia Sub-regions: Supramarginal gyrus: controls sensory discriminations Angular gyrus: phonological storage

13 Brain Ontogeny Temporal lobe Inferior to the parietal lobe
Functions: language and speech interpretation, also important role in thinking, speech, visual processing, & memory Sub-regions: Superior temporal gyrus (Wernicke’s area) Understanding of speech Wernicke’s aphasia Planum temporale: perception of pitch & harmony Transverse temporal gyrus: primary auditory cortex

14 Brain Ontogeny Sub-regions: Damage: epilepsy due to anoxia
Inferior temporal gyrus word & number recognition Fusiform gyrus Facial recognition Damage: epilepsy due to anoxia

15 Brain Ontogeny Occipital lobe Posterior to parietal and temporal lobes
Functions: Visual recognition and processing Damage: blindness due to contra coup effect

16

17 Brain Ontogeny Limbic system
Housed within the cortex and temporal lobe Functions: processing of emotions & formation of memories Main structures: Hippocampus Amygdala Basal ganglia

18 Brain Ontogeny Hippocampus H.M., suffered frequent grand mal seizures
Underwent hippocampectomy & amygdalectomy Led to inability to recognize faces, retrograde and anterograde amnesia Declarative memory impaired Procedural memory intact

19 Brain Ontogeny Amygdala Anterior tips of hippocampus
Fear and rage responses Amygdala → emotions → memory Amygdalectomy → apathy

20 Brain Ontogeny Basal ganglia Collection of subcortical neurons
Function: control of movements Substantia nigra Manufacture of dopamine Parkinson’s disease Destruction of neurons → decreased dopamine Hand, finger, foot tremors Rigid muscles Trouble walking

21 Brain Ontogeny O.C.D. Tourette’s syndrome Treatments:
Levodopa (L-dopa) Removal of globus pallidus Deep brain stimulation O.C.D. Tourette’s syndrome

22 Other Subcortical Brain Structures
Cerebellum Very old brain structure Rapid expansion in modern humans Functions: integration of sensory perception and motor output & control of fine motor movements Lesions/damage → difficulties in equilibrium, balance, and posture

23 Other Subcortical Brain Structures
Brain stem Lower brain structure Pons Receives sensory & motor output → cerebellum Information crosses over to opposite side Reticular formation One of the oldest phylogenetic areas of the brain Sleeping, eating, sex, also attention & motivation Medulla Controls vital functions: heart rate, breathing, & bp

24 Other Subcortical Brain Structures
Hypothalamus Regulates the autonomic nervous system, the endocrine & hormonal systems, and the body’s general homeostasis Thalamus Top of spinal cord Relay station for sensory information Also regulates attention

25 Handedness Both ipsilateral (same-side) and contralateral (opposite-side) connections to the two cerebral hemispheres Stronger contralateral connection 90-95% → right-handed 5-10% → left-handed or non-right-handed Right-handed and most non-right-handed people have speech located in left hemisphere

26 Handedness Many animals also have vocalization ability located in the left hemisphere. Homo habilis (≈ 2 million years ago) → enlarged Broca’s area (left hemisphere; speech production) but not earlier australopithecines Toth (1985) examined stone tools from 1.4 – 1.9 million years ago → more right-handers

27 Ears and Hearing Both ipsilateral and contralateral connections
Stronger contralateral connection For example, right ear → left hemisphere (speech) Left ear → right hemisphere → corpus callosum→ left hemisphere

28 Eyes and Vision Each eye is connected to both hemispheres
Ipsilateral and contralateral connections are equal Left half of each eye → left hemisphere & views the right visual field Right half of each eye → right hemisphere & views the left visual field

29

30 Split-Brain Studies Involves severing the corpus callosum in order to reduce seizures in severely epileptic patients Split-brain patients cannot repeat something they’ve heard in their left ear because the knowledge cannot travel across the corpus callosum to be processed in the left hemisphere

31 Split-Brain Studies Split-brain patients cannot repeat what they see in their left visual field Left visual field → right half of each eye → right hemisphere Hand & eye tasks Will use their left hand to pick up what they saw in their right visual field (TREE) and vice versa

32 Split-Brain Studies Left visual field Right visual field

33 Brain Myths Myth #1: We only use 10% of our brains.
Cannot be measured (walking, sitting, moving, etc.) Vincent et al. (2007) – found cortical activation in unconscious monkeys May have been created to motivate

34 Brain Myths Myth #2: Alcohol destroys brain cells.
Little or no evidence for moderate drinkers with adequate diets However, severe and long-term alcoholism is associated with Korsakoff’s syndrome → memory problems

35 Brain Myths Myth #3A: The brain cannot regenerate its neurons.
There has been some evidence of neurogenesis in only the olfactory bulb and the hippocampus. Myth #3B: The brain can regenerate its neurons. People with massive brain damage usually do not get better. Quite often, they get much worse. Neurogenesis evidence is probably exaggerated.

36 Brain Myths Myth #4: Gay men’s and lesbians’ brains are different from heterosexuals’ brains. Not much evidence for either side. Some evidence for neuronal organization differences in the hippocampus of gay men but this has not shown any cognitive consequence whatsoever.

37 The End


Download ppt "The Rise of Homo sapiens: Chapters 1 & 2"

Similar presentations


Ads by Google