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The Rise of Homo sapiens: Chapters 1 & 2 Introductionand The Brain.

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

1 The Rise of Homo sapiens: Chapters 1 & 2 Introductionand The Brain

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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30 Split-Brain Studies Involves severing the corpus callosum in order to reduce seizures in severely epileptic patients 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 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 Split-brain patients cannot repeat what they see in their left visual field Left visual field → right half of each eye → right hemisphere Left visual field → right half of each eye → right hemisphere Hand & eye tasks Hand & eye tasks Will use their left hand to pick up what they saw in their right visual field (TREE) and vice versa 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. Myth #1: We only use 10% of our brains. Cannot be measured (walking, sitting, moving, etc.) Cannot be measured (walking, sitting, moving, etc.) Vincent et al. (2007) – found cortical activation in unconscious monkeys Vincent et al. (2007) – found cortical activation in unconscious monkeys May have been created to motivate May have been created to motivate

34 Brain Myths Myth #2: Alcohol destroys brain cells. Myth #2: Alcohol destroys brain cells. Little or no evidence for moderate drinkers with adequate diets Little or no evidence for moderate drinkers with adequate diets However, severe and long-term alcoholism is associated with Korsakoff’s syndrome → memory problems 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. Myth #3A: The brain cannot regenerate its neurons. There has been some evidence of neurogenesis in only the olfactory bulb and the hippocampus. There has been some evidence of neurogenesis in only the olfactory bulb and the hippocampus. Myth #3B: The brain can regenerate its neurons. 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. 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. Myth #4: Gay men’s and lesbians’ brains are different from heterosexuals’ brains. Not much evidence for either side. 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. Some evidence for neuronal organization differences in the hippocampus of gay men but this has not shown any cognitive consequence whatsoever.

37 TheEnd


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