Lecture 2: The Hypothalamus (The Behavioural
Control Centre)
Part 1: Anatomy and function of the hypothalamus
The neural basis of emotion and motivated behaviour
Behaviours the hypothalamus has a role in regulating:
• Aggression/ defensive responses
• Sexual activity/ development of partnerships
• Fear responses Commented [IM10]: Behavioural responses to fear stimuli
• Internal body state e.g. body temperature (via ANS; pyloerection, sweating)
• Fluid homeostasis
• Feeding behaviour
• Love; development of close bonds (romantic, parental etc.)
• Diurnal activity (daily rhythms)
Found at ventral aspect of diencephalon, above pituitary, below thalamus. Border by optic chiasm at
rostral edge.
The hypothalamus is comprised of a collection of nuclei with relatively distinct functions (e.g.):
• Suprachiasmatic nucleus – extensive input from optic nerves, information about light levels;
entrains circadian rhythms
• Paraventricular nucleus – regulating feeding behaviour, forming emotive bonds (affiliative
behaviour)
• Arcuate nucleus – regulative feeding behaviour
• Mammillary body – important site of connectivity between thalamus and hypothalamus.
Providing context to sensory information (e.g. should you respond to presented object)
,Inputs:
Input Hypothalamic Nuclei Function
Retina Suprachiasmatic Nucleus Circadian rhythm
Amygdaloid complex Paraventricular nucelus Emotive state of individual
Valence of sensory input (attractive or aversive)
Hippocampus Fibular fornix pathway à Memory-related information (valence)
mammillary bodies
Thalamus Mammillary bodies Sensory information à hypothalamus to select
appropriate response
Reticular formation Wakefulness (attention, active searching
behaviour)
Monoaminergic nuclei Wakefulness (Arousal)
Sleep
Other functions
Nucleus solitarius Provides input from ANS
Mediating autonomic feedback responses from
hypothalamus
Contains baroreceptors; hypothalamus
regulates blood pressure (hormonal release,
heart rate)
Blood e.g. Supraoptic nucleus – Many blood vessels around hypothalamus.
osmosensitive neurons Some areas of reduced BBB, allows
(e.g. lack of water initiates hypothalamic sensory neurons to receive
water-seeking behaviour) energy and information (e.g. osmolarity,
temperature, glucose levels, acidity, hormone
concentrations of blood)
Blood allows hypothalamic mediation of
internal body state regulation
These are the major anatomical connections and key pathways. The hypothalamic connections are
extremely complex.
The hypothalamus integrates a wide range of inputs to select an appropriate output:
• Neuroendocrine axis – hormone release via pituitary gland
o Hypothalamus regulates state of body and behaviour to an extent
• ANS – directly regulate heart rate, digestive function etc.
• Extensive connections to other brain regions – many concerned with mediating behaviours
that the hypothalamus controls
, Output Hypothalamic Nuclei Function
ANS Nucleus Solitarius Hypothalamus regulates internal state of body
Neuroendocrine Pituitary gland Hormones can release directly into blood to
Pineal gland (e.g. melatonin) affect entire body
Reticular formation Arousal (awareness and attentive to problem) Commented [IM11]: e.g. hungry/ thirsty the pathway response
is mediated via the RF, stimulating arousal
Thalamus e.g. If thirsty, activation of è Cortex/ motor regions
drink response (e.g. water- Activation of appropriate (motor) response.
seeking behaviour) via Activity deemed appropriate by the
mammilo-thalamic tract computations of hypothalamus
Limbic System Fibula-fornix è Cortex/motor regions
Stria terminalis Activation of appropriate (motor) response.
Activity deemed appropriate by the
computations of hypothalamus
Hypothalamus has many functions:
• Regulation of physical state (homeostatic/adaptive mechanisms) Commented [IM12]: sweat
• Control of several survival-critical behaviours Commented [IM13]: actively move to cooler environment
• Miscellaneous: learning, memory, attention, sleep etc.
Endocrine output of hypothalamus
Mediated primarily through pituitary gland; divisible into two regions:
• Posterior pituitary (neurohypophysis)
Hypothalamic nerve terminals directly release peptide hormone contents.
o Comprised of secretory nerve terminals; bodies reside in hypothalamic nuclei (e.g.
supraoptic, paraventricular contribute largely)
o Cells produce large quantities of peptide hormones directly into blood stream (via
portal vessel system); travel around body and mediate affects
• Anterior pituitary (adenohypophysis)
Indirect trigger of hormonal release by hypothalamic nerve terminals.
o Comprised of non-neuronal secretory cells, producing steroid hormones
o Regulation of hormonal release via neurotransmitters and releasing factors
§ Factors and NTs released from hypothalamus into portal vessels upstream
o Hormonal contents also released into blood stream, for wide-ranging affects
Different hypothalamic nuclei regulate the release of specific hormones (directly via
neurohypophysis, or indirectly via adenohypophysis).
Control Centre)
Part 1: Anatomy and function of the hypothalamus
The neural basis of emotion and motivated behaviour
Behaviours the hypothalamus has a role in regulating:
• Aggression/ defensive responses
• Sexual activity/ development of partnerships
• Fear responses Commented [IM10]: Behavioural responses to fear stimuli
• Internal body state e.g. body temperature (via ANS; pyloerection, sweating)
• Fluid homeostasis
• Feeding behaviour
• Love; development of close bonds (romantic, parental etc.)
• Diurnal activity (daily rhythms)
Found at ventral aspect of diencephalon, above pituitary, below thalamus. Border by optic chiasm at
rostral edge.
The hypothalamus is comprised of a collection of nuclei with relatively distinct functions (e.g.):
• Suprachiasmatic nucleus – extensive input from optic nerves, information about light levels;
entrains circadian rhythms
• Paraventricular nucleus – regulating feeding behaviour, forming emotive bonds (affiliative
behaviour)
• Arcuate nucleus – regulative feeding behaviour
• Mammillary body – important site of connectivity between thalamus and hypothalamus.
Providing context to sensory information (e.g. should you respond to presented object)
,Inputs:
Input Hypothalamic Nuclei Function
Retina Suprachiasmatic Nucleus Circadian rhythm
Amygdaloid complex Paraventricular nucelus Emotive state of individual
Valence of sensory input (attractive or aversive)
Hippocampus Fibular fornix pathway à Memory-related information (valence)
mammillary bodies
Thalamus Mammillary bodies Sensory information à hypothalamus to select
appropriate response
Reticular formation Wakefulness (attention, active searching
behaviour)
Monoaminergic nuclei Wakefulness (Arousal)
Sleep
Other functions
Nucleus solitarius Provides input from ANS
Mediating autonomic feedback responses from
hypothalamus
Contains baroreceptors; hypothalamus
regulates blood pressure (hormonal release,
heart rate)
Blood e.g. Supraoptic nucleus – Many blood vessels around hypothalamus.
osmosensitive neurons Some areas of reduced BBB, allows
(e.g. lack of water initiates hypothalamic sensory neurons to receive
water-seeking behaviour) energy and information (e.g. osmolarity,
temperature, glucose levels, acidity, hormone
concentrations of blood)
Blood allows hypothalamic mediation of
internal body state regulation
These are the major anatomical connections and key pathways. The hypothalamic connections are
extremely complex.
The hypothalamus integrates a wide range of inputs to select an appropriate output:
• Neuroendocrine axis – hormone release via pituitary gland
o Hypothalamus regulates state of body and behaviour to an extent
• ANS – directly regulate heart rate, digestive function etc.
• Extensive connections to other brain regions – many concerned with mediating behaviours
that the hypothalamus controls
, Output Hypothalamic Nuclei Function
ANS Nucleus Solitarius Hypothalamus regulates internal state of body
Neuroendocrine Pituitary gland Hormones can release directly into blood to
Pineal gland (e.g. melatonin) affect entire body
Reticular formation Arousal (awareness and attentive to problem) Commented [IM11]: e.g. hungry/ thirsty the pathway response
is mediated via the RF, stimulating arousal
Thalamus e.g. If thirsty, activation of è Cortex/ motor regions
drink response (e.g. water- Activation of appropriate (motor) response.
seeking behaviour) via Activity deemed appropriate by the
mammilo-thalamic tract computations of hypothalamus
Limbic System Fibula-fornix è Cortex/motor regions
Stria terminalis Activation of appropriate (motor) response.
Activity deemed appropriate by the
computations of hypothalamus
Hypothalamus has many functions:
• Regulation of physical state (homeostatic/adaptive mechanisms) Commented [IM12]: sweat
• Control of several survival-critical behaviours Commented [IM13]: actively move to cooler environment
• Miscellaneous: learning, memory, attention, sleep etc.
Endocrine output of hypothalamus
Mediated primarily through pituitary gland; divisible into two regions:
• Posterior pituitary (neurohypophysis)
Hypothalamic nerve terminals directly release peptide hormone contents.
o Comprised of secretory nerve terminals; bodies reside in hypothalamic nuclei (e.g.
supraoptic, paraventricular contribute largely)
o Cells produce large quantities of peptide hormones directly into blood stream (via
portal vessel system); travel around body and mediate affects
• Anterior pituitary (adenohypophysis)
Indirect trigger of hormonal release by hypothalamic nerve terminals.
o Comprised of non-neuronal secretory cells, producing steroid hormones
o Regulation of hormonal release via neurotransmitters and releasing factors
§ Factors and NTs released from hypothalamus into portal vessels upstream
o Hormonal contents also released into blood stream, for wide-ranging affects
Different hypothalamic nuclei regulate the release of specific hormones (directly via
neurohypophysis, or indirectly via adenohypophysis).
